WorldWideScience

Sample records for gecko attachment system

  1. Biomimetic wall-shaped hierarchical microstructure for gecko-like attachment.

    Science.gov (United States)

    Kasem, Haytam; Tsipenyuk, Alexey; Varenberg, Michael

    2015-04-21

    Most biological hairy adhesive systems involved in locomotion rely on spatula-shaped terminal elements, whose operation has been actively studied during the last decade. However, though functional principles underlying their amazing performance are now well understood, due to technical difficulties in manufacturing the complex structure of hierarchical spatulate systems, a biomimetic surface structure featuring true shear-induced dynamic attachment still remains elusive. To try bridging this gap, a novel method of manufacturing gecko-like attachment surfaces is devised based on a laser-micromachining technology. This method overcomes the inherent disadvantages of photolithography techniques and opens wide perspectives for future production of gecko-like attachment systems. Advanced smart-performance surfaces featuring thin-film-based hierarchical shear-activated elements are fabricated and found capable of generating friction force of several tens of times the contact load, which makes a significant step forward towards a true gecko-like adhesive.

  2. Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model.

    Science.gov (United States)

    Wu, Xuan; Wang, Xiaojie; Mei, Tao; Sun, Shaoming

    2015-07-08

    This paper proposes a multi-level hierarchical model for the Tokay gecko ( Gekko gecko ) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko 's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko 's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid substrate, the directional adhesion behaviour of the seta has been investigated. The lamella-induced attachment and detachment have been modelled to simulate the active digital hyperextension (DH) and the digital gripping (DG) phenomena. The results suggest that a tiny angular displacement within 0.25° of the lamellar proximal end is necessary in which a fast transition from attachment to detachment or vice versa is induced. The active DH helps release the torque to induce setal non-sliding detachment, while the DG helps apply torque to make the setal adhesion stable. The lamella plays a key role in saving energy during detachment to adapt to its habitat and provides another adhesive function which differs from the friction-dependent setal adhesion system controlled by the dynamic of G. gecko 's body.

  3. Effect of counterface roughness on the friction of bionic wall-shaped microstructures for gecko-like attachments.

    Science.gov (United States)

    Kasem, Haytam; Cohen, Yossi

    2017-08-04

    Hairy adhesive systems involved in gecko locomotion have drawn the interest of many researchers regarding the development of bionic solutions for fast and reversible adhesive technologies. To date, despite extensive efforts to design gecko-inspired adhesive surfaces, adhesion and friction capacities are often evaluated using smooth and rigid counterfaces, in general glass, whereas most natural and artificial surfaces inevitably have a certain level of roughness. For that reason, in this study experiments tested the effects of the substrate roughness on the friction of bionic wale-shaped microstructures for gecko-like attachments. To this end, 12 substrates with different isotropic roughness were prepared using the same Epoxy material. Friction force was measured under various normal loads. It was concluded that classical roughness parameters, considered separately, are not appropriate to explain roughness-related variations in friction force. This has led us to develop a new integrative roughness parameter that combines characteristics of the surface. The parameter is capable of classifying the obtained experimental results in a readable way. An analytical model based on the experimental results has been developed to predict the variation of the friction force as a function of counterface roughness and applied normal load.

  4. Mechanisms of adhesion in geckos.

    Science.gov (United States)

    Autumn, Kellar; Peattie, Anne M

    2002-12-01

    The extraordinary adhesive capabilities of geckos have challenged explanation for millennia, since Aristotle first recorded his observations. We have discovered many of the secrets of gecko adhesion, yet the millions of dry, adhesive setae on the toes of geckos continue to generate puzzling new questions and valuable answers. Each epidermally-derived, keratinous seta ends in hundreds of 200 nm spatular tips, permitting intimate contact with rough and smooth surfaces alike. Prior studies suggested that adhesive force in gecko setae was directly proportional to the water droplet contact angle (θ) , an indicator of the free surface energy of a substrate. In contrast, new theory suggests that adhesion energy between a gecko seta and a surface (W(GS)) is in fact proportional to (1 + cosθ), and only for θ > 60°. A reanalysis of prior data, in combination with our recent study, support the van der Waals hypothesis of gecko adhesion, and contradict surface hydrophobicity as a predictor of adhesion force. Previously, we and our collaborators measured the force production of a single seta. Initial efforts to attach a seta failed because of improper 3D orientation. However, by simulating the dynamics of gecko limbs during climbing (based on force plate data) we discovered that, in single setae, a small normal preload, combined with a 5 μm displacement yielded a very large adhesive force of 200 microNewton (μN), 10 times that predicted by whole-animal measurements. 6.5 million setae of a single tokay gecko attached maximally could generate 130 kg force. This raises the question of how geckos manage to detach their feet in just 15 ms. We discovered that simply increasing the angle that the setal shaft makes with the substrate to 30° causes detachment. Understanding how simultaneous attachment and release of millions of setae are controlled will require an approach that integrates levels ranging from molecules to lizards.

  5. Dynamic self-cleaning in gecko setae via digital hyperextension

    Science.gov (United States)

    Hu, Shihao; Lopez, Stephanie; Niewiarowski, Peter H.; Xia, Zhenhai

    2012-01-01

    Gecko toe pads show strong adhesion on various surfaces yet remain remarkably clean around everyday contaminants. An understanding of how geckos clean their toe pads while being in motion is essential for the elucidation of animal behaviours as well as the design of biomimetic devices with optimal performance. Here, we test the self-cleaning of geckos during locomotion. We provide, to our knowledge, the first evidence that geckos clean their feet through a unique dynamic self-cleaning mechanism via digital hyperextension. When walking naturally with hyperextension, geckos shed dirt from their toes twice as fast as they would if walking without hyperextension, returning their feet to nearly 80 per cent of their original stickiness in only four steps. Our dynamic model predicts that when setae suddenly release from the attached substrate, they generate enough inertial force to dislodge dirt particles from the attached spatulae. The predicted cleaning force on dirt particles significantly increases when the dynamic effect is included. The extraordinary design of gecko toe pads perfectly combines dynamic self-cleaning with repeated attachment/detachment, making gecko feet sticky yet clean. This work thus provides a new mechanism to be considered for biomimetic design of highly reuseable and reliable dry adhesives and devices. PMID:22696482

  6. The effect of water on the gecko adhesive system

    Science.gov (United States)

    Stark, Alyssa Yeager

    The gecko adhesive system is a dry, reversible adhesive that is virtually surface-insensitive due to the utilization of intermolecular van der Waals forces. Remarkably, although detailed models of the adhesive mechanism exist and hundreds of gecko-inspired synthetics have been fabricated, our ability to fully replicate the system still falls short. One reason for this is our limited understanding of how the system performs in natural environments. To begin to resolve this I focused on one particular environmental parameter, water. Although thin layers of water can disrupt van der Waals forces, I hypothesized that geckos are able to retain or regain adhesive function on wet surfaces. I was motivated to investigate this hypothesis because many species of gecko are native to the tropics, a climate where we expect surface water to be prevalent, thus it is likely geckos have some mechanism to overcome the challenges associated with surface water and wetting. Despite the challenge water should pose to adhesion, I found that when tested on hydrophobic substrates geckos cling equally well in air and water. Conversely, on wet hydrophilic substrates geckos cannot support their body weight. Investigating these results further, I found that the superhydrophobic nature of the adhesive toe pads allows geckos to form an air bubble around their foot, which when pressed into contact with a hydrophobic substrate likely removes water from the adhesive interface. When the toe pads are no longer superhydrophobic however, geckos cannot support their body weight and fall from substrates. In order to regain adhesion geckos only need to take about ten steps on a dry substrate to self-dry their toe pads. Finally, when measuring a dynamic component of adhesion, running, we found that geckos are able to maintain speed on misted hydrophobic and hydrophilic substrates, contrary to what we would predict based on static shear adhesion measurements. In conclusion, my research provides a detailed

  7. Staying sticky: contact self-cleaning of gecko-inspired adhesives.

    Science.gov (United States)

    Mengüç, Yigit; Röhrig, Michael; Abusomwan, Uyiosa; Hölscher, Hendrik; Sitti, Metin

    2014-05-06

    The exceptionally adhesive foot of the gecko remains clean in dirty environments by shedding contaminants with each step. Synthetic gecko-inspired adhesives have achieved similar attachment strengths to the gecko on smooth surfaces, but the process of contact self-cleaning has yet to be effectively demonstrated. Here, we present the first gecko-inspired adhesive that has matched both the attachment strength and the contact self-cleaning performance of the gecko's foot on a smooth surface. Contact self-cleaning experiments were performed with three different sizes of mushroom-shaped elastomer microfibres and five different sizes of spherical silica contaminants. Using a load-drag-unload dry contact cleaning process similar to the loads acting on the gecko foot during locomotion, our fully contaminated synthetic gecko adhesives could recover lost adhesion at a rate comparable to that of the gecko. We observed that the relative size of contaminants to the characteristic size of the microfibres in the synthetic adhesive strongly determined how and to what degree the adhesive recovered from contamination. Our approximate model and experimental results show that the dominant mechanism of contact self-cleaning is particle rolling during the drag process. Embedding of particles between adjacent fibres was observed for particles with diameter smaller than the fibre tips, and further studied as a temporary cleaning mechanism. By incorporating contact self-cleaning capabilities, real-world applications of synthetic gecko adhesives, such as reusable tapes, clothing closures and medical adhesives, would become feasible.

  8. Carbon Nanotube-Based Synthetic Gecko Tapes

    Science.gov (United States)

    Dhinojwala, Ali

    2008-03-01

    Wall-climbing geckos have unique ability to attach to different surfaces without the use of any viscoelastic glues. On coming in contact with any surface, the micron-size gecko foot-hairs deform, enabling molecular contact over large areas, thus translating weak van der Waals (vdW) interactions into enormous shear forces. We will present our recent results on the development of synthetic gecko tape using aligned carbon nanotubes to mimic the keratin hairs found on gecko feet. The patterned carbon nanotube-based gecko tape can support a shear stress (36 N/cm^2) nearly four times higher than the gecko foot and sticks to a variety of surfaces, including Teflon. Both the micron-size setae (replicated by nanotube bundles) and nanometer-size spatulas (individual nanotubes) are necessary to achieve macroscopic shear adhesion and to translate the weak vdW interactions into high shear forces. The carbon nanotube based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics and space applications. The mechanism behind these large shear forces and self-cleaning properties of these carbon nanotube based synthetic gecko tapes will be discussed. This work was performed in collaboration with graduate students Liehui Ge, and Sunny Sethi, and collaborators from RPI; Lijie Ci and Professor Pulickel Ajayan.

  9. Geckos as Springs: Mechanics Explain Across-Species Scaling of Adhesion.

    Directory of Open Access Journals (Sweden)

    Casey A Gilman

    Full Text Available One of the central controversies regarding the evolution of adhesion concerns how adhesive force scales as animals change in size, either among or within species. A widely held view is that as animals become larger, the primary mechanism that enables them to climb is increasing pad area. However, prior studies show that much of the variation in maximum adhesive force remains unexplained, even when area is accounted for. We tested the hypothesis that maximum adhesive force among pad-bearing gecko species is not solely dictated by toepad area, but also depends on the ratio of toepad area to gecko adhesive system compliance in the loading direction, where compliance (C is the change in extension (Δ relative to a change in force (F while loading a gecko's adhesive system (C = dΔ/dF. Geckos are well-known for their ability to climb on a range of vertical and overhanging surfaces, and range in mass from several grams to over 300 grams, yet little is understood of the factors that enable adhesion to scale with body size. We examined the maximum adhesive force of six gecko species that vary in body size (~2-100 g. We also examined changes between juveniles and adults within a single species (Phelsuma grandis. We found that maximum adhesive force and toepad area increased with increasing gecko size, and that as gecko species become larger, their adhesive systems become significantly less compliant. Additionally, our hypothesis was supported, as the best predictor of maximum adhesive force was not toepad area or compliance alone, but the ratio of toepad area to compliance. We verified this result using a synthetic "model gecko" system comprised of synthetic adhesive pads attached to a glass substrate and a synthetic tendon (mechanical spring of finite stiffness. Our data indicate that increases in toepad area as geckos become larger cannot fully account for increased adhesive abilities, and decreased compliance must be included to explain the scaling of

  10. Geckos as Springs: Mechanics Explain Across-Species Scaling of Adhesion.

    Science.gov (United States)

    Gilman, Casey A; Imburgia, Michael J; Bartlett, Michael D; King, Daniel R; Crosby, Alfred J; Irschick, Duncan J

    2015-01-01

    One of the central controversies regarding the evolution of adhesion concerns how adhesive force scales as animals change in size, either among or within species. A widely held view is that as animals become larger, the primary mechanism that enables them to climb is increasing pad area. However, prior studies show that much of the variation in maximum adhesive force remains unexplained, even when area is accounted for. We tested the hypothesis that maximum adhesive force among pad-bearing gecko species is not solely dictated by toepad area, but also depends on the ratio of toepad area to gecko adhesive system compliance in the loading direction, where compliance (C) is the change in extension (Δ) relative to a change in force (F) while loading a gecko's adhesive system (C = dΔ/dF). Geckos are well-known for their ability to climb on a range of vertical and overhanging surfaces, and range in mass from several grams to over 300 grams, yet little is understood of the factors that enable adhesion to scale with body size. We examined the maximum adhesive force of six gecko species that vary in body size (~2-100 g). We also examined changes between juveniles and adults within a single species (Phelsuma grandis). We found that maximum adhesive force and toepad area increased with increasing gecko size, and that as gecko species become larger, their adhesive systems become significantly less compliant. Additionally, our hypothesis was supported, as the best predictor of maximum adhesive force was not toepad area or compliance alone, but the ratio of toepad area to compliance. We verified this result using a synthetic "model gecko" system comprised of synthetic adhesive pads attached to a glass substrate and a synthetic tendon (mechanical spring) of finite stiffness. Our data indicate that increases in toepad area as geckos become larger cannot fully account for increased adhesive abilities, and decreased compliance must be included to explain the scaling of adhesion in

  11. Microfabricated adhesive mimicking gecko foot-hair

    Science.gov (United States)

    Geim, A. K.; Dubonos, S. V.; Grigorieva, I. V.; Novoselov, K. S.; Zhukov, A. A.; Shapoval, S. Yu.

    2003-07-01

    The amazing climbing ability of geckos has attracted the interest of philosophers and scientists alike for centuries. However, only in the past few years has progress been made in understanding the mechanism behind this ability, which relies on submicrometre keratin hairs covering the soles of geckos. Each hair produces a miniscule force ~10-7 N (due to van der Waals and/or capillary interactions) but millions of hairs acting together create a formidable adhesion of ~10 N cm-2: sufficient to keep geckos firmly on their feet, even when upside down on a glass ceiling. It is very tempting to create a new type of adhesive by mimicking the gecko mechanism. Here we report on a prototype of such 'gecko tape' made by microfabrication of dense arrays of flexible plastic pillars, the geometry of which is optimized to ensure their collective adhesion. Our approach shows a way to manufacture self-cleaning, re-attachable dry adhesives, although problems related to their durability and mass production are yet to be resolved.

  12. Passively stuck: death does not affect gecko adhesion strength.

    Science.gov (United States)

    Stewart, William J; Higham, Timothy E

    2014-12-01

    Many geckos use adhesive toe pads on the bottom of their digits to attach to surfaces with remarkable strength. Although gecko adhesion has been studied for hundreds of years, gaps exist in our understanding at the whole-animal level. It remains unclear whether the strength and maintenance of adhesion are determined by the animal or are passively intrinsic to the system. Here we show, for the first time, that strong adhesion is produced passively at the whole-animal level. Experiments on both live and recently euthanized tokay geckos (Gekko gecko) revealed that death does not affect the dynamic adhesive force or motion of a gecko foot when pulled along a vertical surface. Using a novel device that applied repeatable and steady-increasing pulling forces to the foot in shear, we found that the adhesive force was similarly high and variable when the animal was alive (mean ± s.d. = 5.4 ± 1.7 N) and within 30 min after death (5.4 ± 2.1 N). However, kinematic analyses showed that live geckos are able to control the degree of toe pad engagement and can rapidly stop strong adhesion by hyperextending the toes. This study offers the first assessment of whole-animal adhesive force under extremely controlled conditions. Our findings reveal that dead geckos maintain the ability to adhere with the same force as living animals, disproving that strong adhesion requires active control. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  13. A microfabricated gecko-inspired controllable and reusable dry adhesive

    International Nuclear Information System (INIS)

    Chary, Sathya; Tamelier, John; Turner, Kimberly

    2013-01-01

    Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ′) of 8–16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ′, along with a large shear force of ∼78 kPa, approaching the 88–226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry. (paper)

  14. A microfabricated gecko-inspired controllable and reusable dry adhesive

    Science.gov (United States)

    Chary, Sathya; Tamelier, John; Turner, Kimberly

    2013-02-01

    Geckos utilize a robust reversible adhesive to repeatedly attach and detach from a variety of vertical and inverted surfaces, using structurally anisotropic micro- and nano-scale fibrillar structures. These fibers, when suitably articulated, are able to control the real area of contact and thereby generate high-to-low van der Waals forces. Key characteristics of the natural system include highly anisotropic adhesion and shear forces for controllable attachment, a high adhesion to initial preload force ratio (μ‧) of 8-16, lack of inter-fiber self-adhesion, and operation over more than 30 000 cycles without loss of adhesion performance. A highly reusable synthetic adhesive has been developed using tilted polydimethylsiloxane (PDMS) half-cylinder micron-scale fibers, retaining up to 77% of the initial value over 10 000 repeated test cycles against a flat glass puck. In comparison with other gecko-inspired adhesives tested over 10 000 cycles or more thus far, this paper reports the highest value of μ‧, along with a large shear force of ˜78 kPa, approaching the 88-226 kPa range of gecko toes. The anisotropic adhesion forces are close to theoretical estimates from the Kendall peel model, quantitatively showing how lateral shearing articulation in a manner similar to the gecko may be used to obtain adhesion anisotropy with synthetic fibers using a combination of tilt angle and anisotropic fiber geometry.

  15. Frictional and elastic energy in gecko adhesive detachment.

    Science.gov (United States)

    Gravish, Nick; Wilkinson, Matt; Autumn, Kellar

    2008-03-06

    Geckos use millions of adhesive setae on their toes to climb vertical surfaces at speeds of over 1 m s(-1). Climbing presents a significant challenge for an adhesive since it requires both strong attachment and easy, rapid removal. Conventional pressure-sensitive adhesives are either strong and difficult to remove (e.g. duct tape) or weak and easy to remove (e.g. sticky notes). We discovered that the energy required to detach adhering tokay gecko setae (W(d)) is modulated by the angle (theta) of a linear path of detachment. Gecko setae resist detachment when dragged towards the animal during detachment (theta = 30 degrees ) requiring W(d) = 5.0+/-0.86(s.e.) J m(-2) to detach, largely due to frictional losses. This external frictional loss is analogous to viscous internal frictional losses during detachment of pressure-sensitive adhesives. We found that, remarkably, setae possess a built-in release mechanism. Setae acted as springs when loaded in tension during attachment and returned elastic energy when detached along the optimal path (theta=130 degrees ), resulting in W(d) = -0.8+/-0.12 J m(-2). The release of elastic energy from the setal shaft probably causes spontaneous release, suggesting that curved shafts may enable easy detachment in natural, and synthetic, gecko adhesives.

  16. Adhesive force of a single gecko foot-hair

    Science.gov (United States)

    Autumn, Kellar; Liang, Yiching A.; Hsieh, S. Tonia; Zesch, Wolfgang; Chan, Wai Pang; Kenny, Thomas W.; Fearing, Ronald; Full, Robert J.

    2000-06-01

    Geckos are exceptional in their ability to climb rapidly up smooth vertical surfaces. Microscopy has shown that a gecko's foot has nearly five hundred thousand keratinous hairs or setae. Each 30-130µm long seta is only one-tenth the diameter of a human hair and contains hundreds of projections terminating in 0.2-0.5µm spatula-shaped structures. After nearly a century of anatomical description, here we report the first direct measurements of single setal force by using a two-dimensional micro-electro-mechanical systems force sensor and a wire as a force gauge. Measurements revealed that a seta is ten times more effective at adhesion than predicted from maximal estimates on whole animals. Adhesive force values support the hypothesis that individual seta operate by van der Waals forces. The gecko's peculiar behaviour of toe uncurling and peeling led us to discover two aspects of setal function which increase their effectiveness. A unique macroscopic orientation and preloading of the seta increased attachment force 600-fold above that of frictional measurements of the material. Suitably orientated setae reduced the forces necessary to peel the toe by simply detaching above a critical angle with the substratum.

  17. Ultrahydrophobicity indicates a non-adhesive default state in gecko setae.

    Science.gov (United States)

    Autumn, Kellar; Hansen, Wendy

    2006-11-01

    Geckos may represent the world's most demanding adhesives application. The adhesive setae on the toes of climbing geckos must adhere strongly yet avoid fouling or attachment at inappropriate times. We tested the hypothesis that gecko setae are non-adhesive in their unloaded default state by comparing the water droplet contact angle (theta) of isolated setal arrays to the smooth surface of eye spectacle scales of tokay geckos (Gekko gecko). At equilibrium, theta was 98.3 +/- 3.4 degrees in spectacle scales of live geckos and 93.3 +/- 3.5 degrees in isolated spectacles. Isolated setal arrays were ultrahydrophobic, with theta of 160.6 +/- 1.3 degrees (means +/- SD). The difference in theta of setal arrays and smooth spectacles indicates a very low contact fraction. Using Cassie's law of surface wettability, we infer that less than 6.6% of the surface of unloaded setae is solid and at least 93.4% is air space. We calculated that the contact fraction must increase from 6.6% in the unloaded state to 46% in the loaded state to account for previously measured values of adhesion. Thus gecko setae may be non-sticky by default because only a very small contact fraction is possible without mechanically deforming the setal array.

  18. Mechanical analyses on the digital behaviour of the Tokay gecko (Gekko gecko) based on a multi-level directional adhesion model

    OpenAIRE

    Wu, Xuan; Wang, Xiaojie; Mei, Tao; Sun, Shaoming

    2015-01-01

    This paper proposes a multi-level hierarchical model for the Tokay gecko (Gekko gecko) adhesive system and analyses the digital behaviour of the G. gecko under macro/meso-level scale. The model describes the structures of G. gecko's adhesive system from the nano-level spatulae to the sub-millimetre-level lamella. The G. gecko's seta is modelled using inextensible fibril based on Euler's elastica theorem. Considering the side contact of the spatular pads of the seta on the flat and rigid subst...

  19. Stick–slip friction of gecko-mimetic flaps on smooth and rough surfaces

    Science.gov (United States)

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L.; Israelachvili, Jacob N.

    2015-01-01

    The discovery and understanding of gecko ‘frictional-adhesion’ adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick–slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick–slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick–slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. PMID:25589569

  20. Influence of substrate modulus on gecko adhesion

    Science.gov (United States)

    Klittich, Mena R.; Wilson, Michael C.; Bernard, Craig; Rodrigo, Rochelle M.; Keith, Austin J.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2017-03-01

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Understanding the adhesion system’s performance on various surfaces can give clues as to gecko behaviour, as well as towards designing synthetic adhesive mimics. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard, rough tree trunks as well as soft, flexible leaves. While gecko adhesion on hard surfaces has been extensively studied, little work has been done on soft surfaces. Here, we investigate for the first time the influence of macroscale and nanoscale substrate modulus on whole animal adhesion on two different substrates (cellulose acetate and polydimethylsiloxane) in air and find that across 5 orders of magnitude in macroscale modulus, there is no change in adhesion. On the nanoscale, however, gecko adhesion is shown to depend on substrate modulus. This suggests that low surface-layer modulus may inhibit the gecko adhesion system, independent of other influencing factors such as macroscale composite modulus and surface energy. Understanding the limits of gecko adhesion is vital for clarifying adhesive mechanisms and in the design of synthetic adhesives for soft substrates (including for biomedical applications and wearable electronics).

  1. Sliding-induced non-uniform pre-tension governs robust and reversible adhesion: a revisit of adhesion mechanisms of geckos.

    Science.gov (United States)

    Cheng, Q H; Chen, B; Gao, H J; Zhang, Y W

    2012-02-07

    Several mechanisms have been proposed in the literature to explain the robust attachment and rapid, controllable detachment of geckos' feet on vertical walls or ceilings, yet, it is still debatable, which one is ultimately responsible for geckos' extraordinary capabilities for robust and reversible adhesion. In this paper, we re-examine some of the key movements of geckos' spatula pads and seta hairs during attachment and detachment, and propose a sequence of simple mechanical steps that would lead to the extraordinary properties of geckos observed in experiments. The central subject under study here is a linear distribution of pre-tension along the spatula pad induced by its sliding motion with respect to a surface. The resulting pre-tension, together with a control of setae's pulling force and angle, not only allows for robust and strong attachment, but also enables rapid and controllable detachment. We perform computational modelling and simulations to validate the following key steps of geckos' adhesion: (i) creation of a linear distribution of pre-tension in spatula through sliding, (ii) operation of an instability envelope controlled by setae's pulling force and angle, (iii) triggering of an adhesion instability leading to partial decohesion along the interface, and (iv) complete detachment of spatula through post-instability peeling. The present work not only reveals novel insights into the adhesion mechanism of geckos, but also develops a powerful numerical simulation approach as well as additional guidelines for bioinspired materials and devices.

  2. Stick-slip friction of gecko-mimetic flaps on smooth and rough surfaces.

    Science.gov (United States)

    Das, Saurabh; Cadirov, Nicholas; Chary, Sathya; Kaufman, Yair; Hogan, Jack; Turner, Kimberly L; Israelachvili, Jacob N

    2015-03-06

    The discovery and understanding of gecko 'frictional-adhesion' adhering and climbing mechanism has allowed researchers to mimic and create gecko-inspired adhesives. A few experimental and theoretical approaches have been taken to understand the effect of surface roughness on synthetic adhesive performance, and the implications of stick-slip friction during shearing. This work extends previous studies by using a modified surface forces apparatus to quantitatively measure and model frictional forces between arrays of polydimethylsiloxane gecko footpad-mimetic tilted microflaps against smooth and rough glass surfaces. Constant attachments and detachments occur between the surfaces during shearing, as described by an avalanche model. These detachments ultimately result in failure of the adhesion interface and have been characterized in this study. Stick-slip friction disappears with increasing velocity when the flaps are sheared against a smooth silica surface; however, stick-slip was always present at all velocities and loads tested when shearing the flaps against rough glass surfaces. These results demonstrate the significance of pre-load, shearing velocity, shearing distances, commensurability and shearing direction of gecko-mimetic adhesives and provide us a simple model for analysing and/or designing such systems. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  3. Too Soft to Stick: Influence of Substrate Modulus on Gecko Adhesion

    Science.gov (United States)

    Wilson, Michael; Klittich, Mena; Bernard, Craig; Rodrigo, Rochelle; Keith, Austin; Niewiarowski, Peter; Dhinojwala, Ali

    The gecko adhesion system fascinates biologists and materials scientists alike for its strong, reversible, glue-free, dry adhesion. Geckos encounter a variety of surfaces in their natural habitats; tropical geckos, such as Gekko gecko, encounter hard rough tree trunks as well as soft flexible leaves. Gecko adhesion on a wide variety of hard surfaces has been extensively studied, however there has been no work focused on adhesion to soft surfaces. Here, we investigate for the first time the influence of substrate modulus on gecko adhesion using two different surfaces (cellulose acetate and polydimethylsiloxane). Understanding the limitations of the gecko system is critical for gecko experimental design as well as for the development of synthetic adhesives, particularly in the biomedical field. National Science Foundation.

  4. Design and fabrication of polymer based dry adhesives inspired by the gecko adhesive system

    Science.gov (United States)

    Jin, Kejia

    There has been significant interest in developing dry adhesives mimicking the gecko adhesive system, which offers several advantages compared to conventional pressure sensitive adhesives. Specifically, gecko adhesive pads have anisotropic adhesion properties: the adhesive pads (spatulae) stick strongly when sheared in one direction but are non-adherent when sheared in the opposite direction. This anisotropy property is attributed to the complex topography of the array of fine tilted and curved columnar structures (setae) that bear the spatulae. In this thesis, easy, scalable methods, relying on conventional and unconventional techniques are presented to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provide anisotropic adhesion properties. In the first part of the study, the anisotropic adhesion and friction properties of samples with various tilt angles to test the validity of a nanoscale tape-peeling model of spatular function are measured. Consistent with the Peel Zone model, samples with lower tilt angles yielded larger adhesion forces. Contact mechanics of the synthetic array were highly anisotropic, consistent with the frictional adhesion model and gecko-like. Based on the original design, a new design of gecko-like dry adhesives was developed which showed superior tribological properties and furthermore showed anisotropic adhesive properties without the need for tilt in the structures. These adhesives can be used to reversibly suspend weights from vertical surfaces (e.g., walls) and, for the first time to our knowledge, horizontal surfaces (e.g., ceilings) by simultaneously and judiciously activating anisotropic friction and adhesion forces. Furthermore, adhesion properties between artificial gecko-inspired dry adhesives and rough substrates with varying roughness are studied. The results suggest that both adhesion and friction forces on a rough substrate depends significantly on the

  5. Carbon nanotube based gecko inspired self-cleaning adhesives

    Science.gov (United States)

    Sethi, Sunny; Ge, Liehui; Ajayan, Pulickel; Ali, Dhinojwala

    2008-03-01

    Wall climbing organisms like geckos have unique ability to attach to different surfaces without use of any viscoelastic material. The hairy structure found in gecko feet allows them to obtain intimate contact over a large area thus allowing then to adhere using van der Waals interactions. Not only high adhesion, the geometry of the hairs makes gecko feet self cleaning, thus allowing them to walk continuously without worrying about loosing adhesive strength. Such properties if mimicked synthetically could form basis of a new class of materials, which, unlike conventional adhesives would show two contradictory properties, self cleaning and high adhesion. Such materials would form essential component of applications like wall climbing robot. We tried to synthesize such material using micropatterened vertically aligned carbon nanotubes. When dealing with large areas, probability of defects in the structure increase, forming patterns instead of using uniform film of carbon nanotubes helps to inhibit crack propagation, thus gives much higher adhesive strength than a uniform film. When carbon nanotube patterns with optimized aspect ratio are used, both high adhesion and self cleaning properties are observed.

  6. Human climbing with efficiently scaled gecko-inspired dry adhesives.

    Science.gov (United States)

    Hawkes, Elliot W; Eason, Eric V; Christensen, David L; Cutkosky, Mark R

    2015-01-06

    Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for synthetic materials, so can gecko adhesion systems provide a baseline for scaling efficiency. In the tokay gecko (Gekko gecko), a scaling power law has been reported relating the maximum shear stress σmax to the area A: σmax ∝ A(-1/4). We present a mechanical concept which improves upon the gecko's non-uniform load-sharing and results in a nearly even load distribution over multiple patches of gecko-inspired adhesive. We created a synthetic adhesion system incorporating this concept which shows efficient scaling across four orders of magnitude of area, yielding an improved scaling power law: σmax ∝ A(-1/50). Furthermore, we found that the synthetic adhesion system does not fail catastrophically when a simulated failure is induced on a portion of the adhesive. In a practical demonstration, the synthetic adhesion system enabled a 70 kg human to climb vertical glass with 140 cm(2) of adhesive per hand. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  7. Biomechanics of gecko locomotion: the patterns of reaction forces on inverted, vertical and horizontal substrates

    International Nuclear Information System (INIS)

    Wang, Zhouyi; Dai, Zhendong; Ji, Aihong; Xing, Qiang; Ren, Lei; Dai, Liming

    2015-01-01

    The excellent locomotion ability of geckos on various rough and/or inclined substrates has attracted scientists’ attention for centuries. However, the moving ability of gecko-mimicking robots on various inclined surfaces still lags far behind that of geckos, mainly because our understanding of how geckos govern their locomotion is still very poor. To reveal the fundamental mechanism of gecko locomotion and also to facilitate the design of gecko-mimicking robots, we have measured the reaction forces (RFs) acting on each individual foot of moving geckos on inverted, vertical and horizontal substrates (i.e. ceiling, wall and floor), have associated the RFs with locomotion behaviors by using high-speed camera, and have presented the relationships of the force components with patterns of reaction forces (PRFs). Geckos generate different PRF on ceiling, wall and floor, that is, the PRF is determined by the angles between the direction of gravity and the substrate on which geckos move. On the ceiling, geckos produce reversed shear forces acting on the front and hind feet, which pull away from the body in both lateral and fore-aft directions. They use a very large supporting angle from 21° to 24° to reduce the forces acting on their legs and feet. On the floor, geckos lift their bodies using a supporting angle from 76° to 78°, which not only decreases the RFs but also improves their locomotion ability. On the wall, geckos generate a reliable self-locking attachment by using a supporting angle of 14.8°, which is only about half of the critical angle of detachment. (paper)

  8. Complete mitochondrial genome of the red-spotted tokay gecko (Gekko gecko, Reptilia: Gekkonidae): comparison of red- and black-spotted tokay geckos.

    Science.gov (United States)

    Qin, Xin-Min; Qian, Fang; Zeng, De-Long; Liu, Xiao-Can; Li, Hui-Min

    2011-10-01

    Here, we sequenced the complete mitochondrial genome of the red-spotted tokay gecko (Squamata: Gekkonidae). The genome is 16,590 bp in size. Its gene arrangement pattern was identical with that of black-spotted tokay gecko. We compared the mitochondrial genome of red-spotted tokay gecko with that of the black-spotted tokay gecko. Nucleotide sequence of the two whole mitochondrial genomes was 97.99% similar, and the relatively high similarity seems to indicate that they may be separated at the subspecies level. The information of mitochondrial genome comparison of the two morphological types of tokay gecko is discussed in detail.

  9. Assistive Free-Flyers with Gecko-Inspired Adhesive Appendages for Automated Logistics in Space

    Data.gov (United States)

    National Aeronautics and Space Administration — Gecko-inspired adhesives provide a new capability for assistive free fliers (AFF) in space. In comparison with conventional grippers, they make it possible to attach...

  10. Fabrication and properties of dual-level hierarchical structures mimicking gecko foot hairs.

    Science.gov (United States)

    Zhang, Peng; Liu, Shiyuan; Lv, Hao

    2013-02-01

    In nature, geckos have extraordinary adhesive capabilities. The multi-scale hierarchical structure of the gecko foot hairs, especially the high-aspect-ratio structure of its micro-scale seta and nano-scale spatulae is the critical factor of the gecko's ability to adopt and stick to any different surface with powerful adhesion force. In this paper, we present a simple and effective approach to fabricate dual-level hierarchical structures mimicking gecko foot hairs. Polydimethyl-siloxane (PDMS) hierarchical arrays were fabricated by demolding from a double stack mold that was composed of an SU-8 mold by thick film photolithography and a silicon mold by inductively coupled plasma (ICP) etching. Top pillars of the fabricated structures have 3 micom diameter and 18 microm in height, while base pillars have 25 microm diameter and 40 microm in height. The water droplet contact angle tests indicate that the hierarchical structures increase the hydrophobic property significantly compared with the single-level arrays and the unstructured polymers, exhibiting superhydrophobicity (154.2 degrees) like the Tokay gecko's (160.9 degrees). The shear force tests show that the top pillars make attachment through side contact with a value of about 0.25 N/cm2, and moreover, the hierarchical structures are demonstrated to be more suitable for contacting with rough surfaces.

  11. Spatial model of the gecko foot hair: functional significance of highly specialized non-uniform geometry.

    Science.gov (United States)

    Filippov, Alexander E; Gorb, Stanislav N

    2015-02-06

    One of the important problems appearing in experimental realizations of artificial adhesives inspired by gecko foot hair is so-called clusterization. If an artificially produced structure is flexible enough to allow efficient contact with natural rough surfaces, after a few attachment-detachment cycles, the fibres of the structure tend to adhere one to another and form clusters. Normally, such clusters are much larger than original fibres and, because they are less flexible, form much worse adhesive contacts especially with the rough surfaces. Main problem here is that the forces responsible for the clusterization are the same intermolecular forces which attract fibres to fractal surface of the substrate. However, arrays of real gecko setae are much less susceptible to this problem. One of the possible reasons for this is that ends of the seta have more sophisticated non-uniformly distributed three-dimensional structure than that of existing artificial systems. In this paper, we simulated three-dimensional spatial geometry of non-uniformly distributed branches of nanofibres of the setal tip numerically, studied its attachment-detachment dynamics and discussed its advantages versus uniformly distributed geometry.

  12. GECKO: a complete large-scale gene expression analysis platform

    Directory of Open Access Journals (Sweden)

    Heuer Michael

    2004-12-01

    Full Text Available Abstract Background Gecko (Gene Expression: Computation and Knowledge Organization is a complete, high-capacity centralized gene expression analysis system, developed in response to the needs of a distributed user community. Results Based on a client-server architecture, with a centralized repository of typically many tens of thousands of Affymetrix scans, Gecko includes automatic processing pipelines for uploading data from remote sites, a data base, a computational engine implementing ~ 50 different analysis tools, and a client application. Among available analysis tools are clustering methods, principal component analysis, supervised classification including feature selection and cross-validation, multi-factorial ANOVA, statistical contrast calculations, and various post-processing tools for extracting data at given error rates or significance levels. On account of its open architecture, Gecko also allows for the integration of new algorithms. The Gecko framework is very general: non-Affymetrix and non-gene expression data can be analyzed as well. A unique feature of the Gecko architecture is the concept of the Analysis Tree (actually, a directed acyclic graph, in which all successive results in ongoing analyses are saved. This approach has proven invaluable in allowing a large (~ 100 users and distributed community to share results, and to repeatedly return over a span of years to older and potentially very complex analyses of gene expression data. Conclusions The Gecko system is being made publicly available as free software http://sourceforge.net/projects/geckoe. In totality or in parts, the Gecko framework should prove useful to users and system developers with a broad range of analysis needs.

  13. Thermally switchable adhesions of polystyrene-block-poly(n-isopropylacrylamide) copolymer pillar array mimicking climb attitude of geckos

    Science.gov (United States)

    Chen, Jem-Kun; Wang, Jing-Hong; Chang, Jia-Yaw; Fan, Shih-Kang

    2012-09-01

    Inspired by the gecko foot pad, we fabricated polystyrene-block-poly(N-isopropylacrylamide) (PS-b-PNIPAAm) copolymer pillar array to mimic climbing attitude of a gecko, alternately attach to and detach from a surface. The pillar array structure of the PS segment significantly enhances both of the hydrophilic and hydrophobic property of PNIPAAm segment tips at 25 and 50 °C, respectively, which could generate alternating adhesive forces of approximately 120 and 11 nN. The dramatic change in adhesive and friction force difference at 25 and 50 °C may guide the design of bio-inspired artificial analogues, which could approach gecko's climbing behavior.

  14. Selection of egg attachment sites by the Indian Golden Gecko Calodactylodes aureus (Beddome, 1870 (Reptilia: Gekkonidae in Andhra Pradesh, India

    Directory of Open Access Journals (Sweden)

    R. Sreekar

    2010-10-01

    Full Text Available Some geckos lay eggs at communal egg deposition sites with as many as 300 eggs per site. Selection of egg deposition sites is important to avoid egg damage and predation. We investigated survival rates of communal egg clutches of the Indian Golden Gecko Calodactylodes aureus (Reptilia: Gekkonidae. Our results show that communal clutches have a higher survival rate in sites with water bodies and without anthropogenic activities, in comparison to sites having the opposite combination. These findings are discussed in the context of the status of this gecko.

  15. Gecko-Inspired Carbon Nanotube-Based Adhesives

    Science.gov (United States)

    Ge, Liehui; Sethi, Sunny; Goyal, Anubha; Ci, Lijie; Ajayan, Pulickel; Dhinojwala, Ali

    2009-03-01

    Nature has developed hierarchical hairy structure on the wall-climbing gecko's foot, consisting of microscopic hairs called setae, which further split into hundreds of smaller structures called spatulas. In the last five years, numerous attempts to mimic gecko foot-hair using polymer soft molding and photolithography methods have been reported. However, most of these polymer-based synthetic gecko hairs fall short of the clinging ability of geckos. Vertically aligned carbon nanotubes (CNT) have shown strong adhesion at nanometer scale. Here, we present our work on developing CNT-based macroscopic flexible tape mimicking the hierarchical structure found on gecko's foot. The synthetic gecko tape is made by transferring aligned CNT array onto flexible polymer tape. The unpatterned CNT-gecko tape can support a shear force stress similar to gecko foot (10 N/cm^2). The supported shear stress increase by a factor of four, when we use micro-patterned CNT patches (50 to 500 μm). We find that both setae (replicated by CNT bundles) and spatulas (individual CNT) are necessary to achieve large macroscopic shear adhesion. The carbon nanotube-based tape offers an excellent synthetic option as a dry conductive reversible adhesive in microelectronics, robotics, and space applications.

  16. Evidence for van der Waals adhesion in gecko setae.

    Science.gov (United States)

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A; Peattie, Anne M; Hansen, Wendy R; Sponberg, Simon; Kenny, Thomas W; Fearing, Ronald; Israelachvili, Jacob N; Full, Robert J

    2002-09-17

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well to strongly hydrophobic and strongly hydrophilic, polarizable surfaces. Adhesion of a single isolated gecko seta was equally effective on the hydrophobic and hydrophilic surfaces of a microelectro-mechanical systems force sensor. A van der Waals mechanism implies that the remarkable adhesive properties of gecko setae are merely a result of the size and shape of the tips, and are not strongly affected by surface chemistry. Theory predicts greater adhesive forces simply from subdividing setae to increase surface density, and suggests a possible design principle underlying the repeated, convergent evolution of dry adhesive microstructures in gecko, anoles, skinks, and insects. Estimates using a standard adhesion model and our measured forces come remarkably close to predicting the tip size of Tokay gecko seta. We verified the dependence on size and not surface type by using physical models of setal tips nanofabricated from two different materials. Both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures.

  17. Geckos significantly alter foot orientation to facilitate adhesion during downhill locomotion.

    Science.gov (United States)

    Birn-Jeffery, Aleksandra V; Higham, Timothy E

    2014-10-01

    Geckos employ their adhesive system when moving up an incline, but the directionality of the system may limit function on downhill surfaces. Here, we use a generalist gecko to test whether limb modulation occurs on downhill slopes to allow geckos to take advantage of their adhesive system. We examined three-dimensional limb kinematics for geckos moving up and down a 45° slope. Remarkably, the hind limbs were rotated posteriorly on declines, resulting in digit III of the pes facing a more posterior direction (opposite to the direction of travel). No significant changes in limb orientation were found in any other condition. This pes rotation leads to a dramatic shift in foot function that facilitates the use of the adhesive system as a brake/stabilizer during downhill locomotion and, although this rotation is not unique to geckos, it is significant for the deployment of adhesion. Adhesion is not just advantageous for uphill locomotion but can be employed to help deal with the effects of gravity during downhill locomotion, highlighting the incredible multi-functionality of this key innovation. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  18. Normally occurring intersexuality and testosterone induced plasticity in the copulatory system of adult leopard geckos.

    Science.gov (United States)

    Holmes, Melissa M; Putz, Oliver; Crews, David; Wade, Juli

    2005-04-01

    The copulatory neuromuscular system of lizards is highly sexually dimorphic. Adult males possess bilateral penises called hemipenes, which are independently controlled by two muscles, the retractor penis magnus (RPM) and transversus penis (TPN). These structures are not obvious in adult females. However, in adult female leopard geckos (Eublepharis macularius), testosterone induces hemipene growth. We investigated whether these structures develop de novo in adulthood or are histologically present as rudimentary structures in the female leopard gecko. We also investigated the extent of sexual dimorphisms and plasticity in the associated neuromuscular components. To do this, we compared copulatory morphology (sizes of hemipenes, RPM and TPN muscle fibers, and associated motoneurons, as well as motoneuron and RPM fiber number) in adult females treated with testosterone, control females, and control males. All of the geckos possessed hemipenes, RPMs and TPNs, but these structures were indeed vestigial in control females. Testosterone induced striking increases in hemipene and copulatory muscle fiber size in females, but not to levels equivalent to control males. In parallel, males with increased levels of androgenic activity had larger hemipenes, suggesting naturally occurring steroid-induced plasticity. Copulatory motoneurons were not sexually dimorphic in size or number, and these measures did not respond to testosterone. The data demonstrate that the copulatory system of leopard geckos, in which gonadal sex is determined by egg incubation temperature, differs from that of many species (both reptilian and mammalian) with genotypic sex determination. Indeed, the system is remarkable in that adult females have normally occurring intersex characteristics and they exhibit substantial steroid-induced morphological plasticity in adulthood.

  19. Histology and ultrastructure of the integumental chromatophores in tokay gecko (Gekko gecko) (Linnaeus, 1758) skin

    OpenAIRE

    Szyd?owski, Pawe?; Madej, Jan Pawe?; Mazurkiewicz-Kania, Marta

    2017-01-01

    This paper describes the relationship between the arrangement of dermal chromatophores in tokay gecko (Gekko gecko) skin and the formation of wild-type colouration, with emphasis on the ultrastructure of chromatophores. The samples of the tokay gecko skin were collected from wild-type colouration adult specimens. Morphology and distribution of chromatophores was determined by using light microscopy and transmission electron microscopy. The present study revealed that orange/red coloured skin ...

  20. Stress distribution and contact area measurements of a gecko toe using a high-resolution tactile sensor.

    Science.gov (United States)

    Eason, Eric V; Hawkes, Elliot W; Windheim, Marc; Christensen, David L; Libby, Thomas; Cutkosky, Mark R

    2015-02-02

    The adhesive systems of geckos have been widely studied and have been a great source of bioinspiration. Load-sharing (i.e. preventing stress concentrations through equal distribution of loads) is necessary to maximize the performance of an adhesive system, but it is not known to what extent load-sharing occurs in gecko toes. In this paper, we present in vivo measurements of the stress distribution and contact area on the toes of a tokay gecko (Gekko gecko) using a custom tactile sensor with 100 μm spatial resolution. We found that the stress distributions were nonuniform, with large variations in stress between and within lamellae, suggesting that load-sharing in the tokay gecko is uneven. These results may be relevant to the understanding of gecko morphology and the design of improved synthetic adhesive systems.

  1. Stress distribution and contact area measurements of a gecko toe using a high-resolution tactile sensor

    International Nuclear Information System (INIS)

    Eason, Eric V; Hawkes, Elliot W; Christensen, David L; Cutkosky, Mark R; Windheim, Marc; Libby, Thomas

    2015-01-01

    The adhesive systems of geckos have been widely studied and have been a great source of bioinspiration. Load-sharing (i.e. preventing stress concentrations through equal distribution of loads) is necessary to maximize the performance of an adhesive system, but it is not known to what extent load-sharing occurs in gecko toes. In this paper, we present in vivo measurements of the stress distribution and contact area on the toes of a tokay gecko (Gekko gecko) using a custom tactile sensor with 100 μm spatial resolution. We found that the stress distributions were nonuniform, with large variations in stress between and within lamellae, suggesting that load-sharing in the tokay gecko is uneven. These results may be relevant to the understanding of gecko morphology and the design of improved synthetic adhesive systems. (paper)

  2. How Do Geckos Stick?

    Science.gov (United States)

    Short, Harold; Lundsgaard, Morten F. V.; Krajcik, Joseph S.

    2008-01-01

    Understanding how geckos--small lizards belonging to the family "Gekkonindae"--can "defy gravity" and walk across a ceiling provides a fascinating frame through which students can not only learn valuable content about electrostatic forces, but also engage in authentic scientific practice and explore new technologies based on gecko adhesion. In…

  3. Histology and ultrastructure of the integumental chromatophores in tokay gecko (Gekko gecko) (Linnaeus, 1758) skin.

    Science.gov (United States)

    Szydłowski, Paweł; Madej, Jan Paweł; Mazurkiewicz-Kania, Marta

    2017-01-01

    This paper describes the relationship between the arrangement of dermal chromatophores in tokay gecko ( Gekko gecko ) skin and the formation of wild-type colouration, with emphasis on the ultrastructure of chromatophores. The samples of the tokay gecko skin were collected from wild-type colouration adult specimens. Morphology and distribution of chromatophores was determined by using light microscopy and transmission electron microscopy. The present study revealed that orange/red coloured skin of G. gecko contained erythrophores, which were located under basement membrane, and usually comprised deeper situated iridophores and melanophores which were form single layer with iridophores or were occupying the deepest region of dermis. In orange/red coloured skin, erythrophores were the predominant chromatophores. However in blue areas these cells occurred in small numbers or were not noticed at all. In blue pigmented areas predominated iridophores and melanophores. Iridophores were found just under basement membrane, but this superficial location of iridophores occured only in areas without erythrophores. Distribution of erythrophores, melanophores, and iridophores determines the characteristic blue colour of the tokay gecko skin with orange/red dots on the whole body.

  4. Gecko toe and lamellar shear adhesion on macroscopic, engineered rough surfaces.

    Science.gov (United States)

    Gillies, Andrew G; Henry, Amy; Lin, Hauwen; Ren, Angela; Shiuan, Kevin; Fearing, Ronald S; Full, Robert J

    2014-01-15

    The role in adhesion of the toes and lamellae - intermediate-sized structures - found on the gecko foot remains unclear. Insight into the function of these structures can lead to a more general understanding of the hierarchical nature of the gecko adhesive system, but in particular how environmental topology may relate to gecko foot morphology. We sought to discern the mechanics of the toes and lamellae by examining gecko adhesion on controlled, macroscopically rough surfaces. We used live Tokay geckos, Gekko gecko, to observe the maximum shear force a gecko foot can attain on an engineered substrate constructed with sinusoidal patterns of varying amplitudes and wavelengths in sizes similar to the dimensions of the toes and lamellae structures (0.5 to 6 mm). We found shear adhesion was significantly decreased on surfaces that had amplitudes and wavelengths approaching the lamella length and inter-lamella spacing, losing 95% of shear adhesion over the range tested. We discovered that the toes are capable of adhering to surfaces with amplitudes much larger than their dimensions even without engaging claws, maintaining 60% of shear adhesion on surfaces with amplitudes of 3 mm. Gecko adhesion can be predicted by the ratio of the lamella dimensions to surface feature dimensions. In addition to setae, remarkable macroscopic-scale features of gecko toes and lamellae that include compliance and passive conformation are necessary to maintain contact, and consequently, generate shear adhesion on macroscopically rough surfaces. Findings on the larger scale structures in the hierarchy of gecko foot function could provide the biological inspiration to drive the design of more effective and versatile synthetic fibrillar adhesives.

  5. A model of frequency tuning in the basilar papilla of the Tokay gecko, Gekko gecko.

    Science.gov (United States)

    Authier, S; Manley, G A

    1995-01-01

    This paper uses the quantitative details of the anatomy of the auditory papilla in the Tokay gecko Gekko gecko (as described in the companion paper) to make a quantitative model predicting the tonotopic organization of two of the three papillar areas. Assuming that hair-cell bundle stiffness is similar to that of other species, a model of resonance frequencies for the apical areas of the papilla was constructed, taking into account factors such as the number of hair cells per resonant unit, their bundle dimensions, the volume of the tectorial mass, etc. The model predicts that the apical pre- and postaxial areas, although anatomically adjacent, respond to different frequency ranges, a phenomenon not yet reported from any vertebrate. The model predicts that together, these areas respond best to frequencies between 1.1 and 5.3 kHz, close to the range found physiologically [Eatock et al. (1981) J. Comp. Physiol. 142, 203-218] (0.8 to 5 kHz) for the high-frequency range for this species. Only physiological experiments tracing responses to specific papillar nerve fibres can confirm or refute these interesting predictions of the model. The model also indicates that, compared to free-standing hair-cell bundles, the semi-isolated tectorial structures called sallets not only lower the range of characteristic frequencies but also increase the frequency selectivity of the attached hair cells.

  6. Ecological effects of the invasive giant madagascar day gecko on endemic mauritian geckos: applications of binomial-mixture and species distribution models.

    Science.gov (United States)

    Buckland, Steeves; Cole, Nik C; Aguirre-Gutiérrez, Jesús; Gallagher, Laura E; Henshaw, Sion M; Besnard, Aurélien; Tucker, Rachel M; Bachraz, Vishnu; Ruhomaun, Kevin; Harris, Stephen

    2014-01-01

    The invasion of the giant Madagascar day gecko Phelsuma grandis has increased the threats to the four endemic Mauritian day geckos (Phelsuma spp.) that have survived on mainland Mauritius. We had two main aims: (i) to predict the spatial distribution and overlap of P. grandis and the endemic geckos at a landscape level; and (ii) to investigate the effects of P. grandis on the abundance and risks of extinction of the endemic geckos at a local scale. An ensemble forecasting approach was used to predict the spatial distribution and overlap of P. grandis and the endemic geckos. We used hierarchical binomial mixture models and repeated visual estimate surveys to calculate the abundance of the endemic geckos in sites with and without P. grandis. The predicted range of each species varied from 85 km2 to 376 km2. Sixty percent of the predicted range of P. grandis overlapped with the combined predicted ranges of the four endemic geckos; 15% of the combined predicted ranges of the four endemic geckos overlapped with P. grandis. Levin's niche breadth varied from 0.140 to 0.652 between P. grandis and the four endemic geckos. The abundance of endemic geckos was 89% lower in sites with P. grandis compared to sites without P. grandis, and the endemic geckos had been extirpated at four of ten sites we surveyed with P. grandis. Species Distribution Modelling, together with the breadth metrics, predicted that P. grandis can partly share the equivalent niche with endemic species and survive in a range of environmental conditions. We provide strong evidence that smaller endemic geckos are unlikely to survive in sympatry with P. grandis. This is a cause of concern in both Mauritius and other countries with endemic species of Phelsuma.

  7. Ecological effects of the invasive giant madagascar day gecko on endemic mauritian geckos: applications of binomial-mixture and species distribution models.

    Directory of Open Access Journals (Sweden)

    Steeves Buckland

    Full Text Available The invasion of the giant Madagascar day gecko Phelsuma grandis has increased the threats to the four endemic Mauritian day geckos (Phelsuma spp. that have survived on mainland Mauritius. We had two main aims: (i to predict the spatial distribution and overlap of P. grandis and the endemic geckos at a landscape level; and (ii to investigate the effects of P. grandis on the abundance and risks of extinction of the endemic geckos at a local scale. An ensemble forecasting approach was used to predict the spatial distribution and overlap of P. grandis and the endemic geckos. We used hierarchical binomial mixture models and repeated visual estimate surveys to calculate the abundance of the endemic geckos in sites with and without P. grandis. The predicted range of each species varied from 85 km2 to 376 km2. Sixty percent of the predicted range of P. grandis overlapped with the combined predicted ranges of the four endemic geckos; 15% of the combined predicted ranges of the four endemic geckos overlapped with P. grandis. Levin's niche breadth varied from 0.140 to 0.652 between P. grandis and the four endemic geckos. The abundance of endemic geckos was 89% lower in sites with P. grandis compared to sites without P. grandis, and the endemic geckos had been extirpated at four of ten sites we surveyed with P. grandis. Species Distribution Modelling, together with the breadth metrics, predicted that P. grandis can partly share the equivalent niche with endemic species and survive in a range of environmental conditions. We provide strong evidence that smaller endemic geckos are unlikely to survive in sympatry with P. grandis. This is a cause of concern in both Mauritius and other countries with endemic species of Phelsuma.

  8. Run don't walk: locomotor performance of geckos on wet substrates.

    Science.gov (United States)

    Stark, Alyssa Y; Ohlemacher, Jocelyn; Knight, Ashley; Niewiarowski, Peter H

    2015-08-01

    The gecko adhesive system has been under particular scrutiny for over a decade, as the field has recently attracted attention for its application to bio-inspired design. However, little is known about how the adhesive system behaves in ecologically relevant conditions. Geckos inhabit a variety of environments, many of which are characterized by high temperature, humidity and rain. The van der Waals-based gecko adhesive system should be particularly challenged by wet substrates because water can disrupt the intimate contact necessary for adhesion. While a few previous studies have focused on the clinging ability of geckos on wet substrates, we tested a dynamic performance characteristic, sprint velocity. To better understand how substrate wettability and running orientation affect locomotor performance of multiple species on wet substrates, we measured average sprint velocity of five species of gecko on substrates that were either hydrophilic or intermediately wetting and oriented either vertically or horizontally. Surprisingly, we found no indication that wet substrates impact average sprint velocity over 1 m, and rather, in some species, sprint velocity was increased on wet substrates rather than reduced. When investigating physical characteristics and behavior that may be associated with running on wet substrates, such as total number of stops, slips and wet toes at the completion of a race, we found that there may be habitat-related differences between some species. Our results show that in general, unlike clinging and walking, geckos running along wet substrates suffer no significant loss in locomotor performance over short distances. © 2015. Published by The Company of Biologists Ltd.

  9. Gecko Adhesion on Wet and Dry Patterned Substrates.

    Directory of Open Access Journals (Sweden)

    Alyssa Y Stark

    Full Text Available Perhaps one of the most astounding characteristics of the gecko adhesive system is its versatility. Geckos can locomote across complex substrates in a variety of conditions with apparent ease. In contrast, many of our synthetic pressure sensitive adhesives fail on substrates that are dirty, wet or rough. Although many studies have investigated the effect of environmental challenges on performance, the interaction of multiple, potentially compromising variables is studied less often. Here we focus on substrate structure and surface water, both of which are highly relevant to the biological system and to synthetic design. To do this we utilized a highly controlled, patterned substrate (Sharklet®, by Sharklet® Technologies Inc.. This allowed us to test independently and jointly the effects of reduced surface area substrates, with a defined pattern, on adhesion in both air and water. Our results show that adhesion is not significantly impaired in air, whereas surface area and pattern significantly affect adhesion in water. These findings highlight the need to study multiple parameters that are relevant to the gecko adhesive system to further improve our understanding of the biological system and to design better, more versatile synthetics.

  10. Robust self-cleaning and micromanipulation capabilities of gecko spatulae and their bio-mimics

    Science.gov (United States)

    Xu, Quan; Wan, Yiyang; Hu, Travis Shihao; Liu, Tony X.; Tao, Dashuai; Niewiarowski, Peter H.; Tian, Yu; Liu, Yue; Dai, Liming; Yang, Yanqing; Xia, Zhenhai

    2015-11-01

    Geckos have the extraordinary ability to prevent their sticky feet from fouling while running on dusty walls and ceilings. Understanding gecko adhesion and self-cleaning mechanisms is essential for elucidating animal behaviours and rationally designing gecko-inspired devices. Here we report a unique self-cleaning mechanism possessed by the nano-pads of gecko spatulae. The difference between the velocity-dependent particle-wall adhesion and the velocity-independent spatula-particle dynamic response leads to a robust self-cleaning capability, allowing geckos to efficiently dislodge dirt during their locomotion. Emulating this natural design, we fabricate artificial spatulae and micromanipulators that show similar effects, and that provide a new way to manipulate micro-objects. By simply tuning the pull-off velocity, our gecko-inspired micromanipulators, made of synthetic microfibers with graphene-decorated micro-pads, can easily pick up, transport, and drop-off microparticles for precise assembling. This work should open the door to the development of novel self-cleaning adhesives, smart surfaces, microelectromechanical systems, biomedical devices, and more.

  11. Radiographic examinations of the leopard gecko, Eublepharis macularius

    International Nuclear Information System (INIS)

    Bayer, S.M.

    2002-11-01

    The anatomy of the Leopard gecko, Eublepharis macularius, and the technique and the diagnostic possibilities of the radiologic and computed-tomographic examination of lizards are summarized in a bibliography. Some aspects of the topographic anatomy of this species are illustrated by one necropsy. The various parts of the gastrointestinal system were identified by histological examinations. 15 preparations of wild captured Leopard geckos were examined radiographically to describe the physiological appearance of the skeleton.15 patients received plain radiographs. 8 different boxes for the immobilization of geckos were tested for practical use. The skeleton and the respiratory tract were fully visible on all x-ray images. The differentiation of the gastrointestinal tract was increased when containing radioopaque material like sand. Eggs with calcified shells were the only detectable parts from the urogenital tract. 2 patients with anorexia and weight loss were administered 0,5 ml of a Gastrografin-water mixture in the ratio 1:3. The dosage was 2,9 or 4,9 ml Gastrografin/kg respectively. The gastrointestinal tract and the surface of the mucous membrane could be visualized very well. The first excretion of the contrast medium resulted 18 - 34 or 28 - 45 hours respectively after the administration. On one dead Leopard gecko a computed tomographic examination was done. This allowed the 3D-reconstruction of the skeleton. The advantages and disadvantages of the various fixation techniques are discussed. The possibilities of radiologic diagnostic imaging techniques for geckos are described. (author)

  12. From the Cover: Evidence for van der Waals adhesion in gecko setae

    Science.gov (United States)

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A.; Peattie, Anne M.; Hansen, Wendy R.; Sponberg, Simon; Kenny, Thomas W.; Fearing, Ronald; Israelachvili, Jacob N.; Full, Robert J.

    2002-09-01

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well to strongly hydrophobic and strongly hydrophilic, polarizable surfaces. Adhesion of a single isolated gecko seta was equally effective on the hydrophobic and hydrophilic surfaces of a microelectro-mechanical systems force sensor. A van der Waals mechanism implies that the remarkable adhesive properties of gecko setae are merely a result of the size and shape of the tips, and are not strongly affected by surface chemistry. Theory predicts greater adhesive forces simply from subdividing setae to increase surface density, and suggests a possible design principle underlying the repeated, convergent evolution of dry adhesive microstructures in gecko, anoles, skinks, and insects. Estimates using a standard adhesion model and our measured forces come remarkably close to predicting the tip size of Tokay gecko seta. We verified the dependence on size and not surface type by using physical models of setal tips nanofabricated from two different materials. Both artificial setal tips stuck as predicted and provide a path to manufacturing the first dry, adhesive microstructures.

  13. Adhesional instabilities and gecko locomotion

    Science.gov (United States)

    Williams, John A.

    2015-01-01

    Geckos possess a remarkable ability to run rapidly on both walls and ceilings and in recent years the mechanisms that underlie this facility have come under close scrutiny. It is now generally agreed that one of the principal mechanisms of adhesion relies on the action of van der Waal forces acting between the final extremely fine structure of the gecko toe and the underlying substrate. High speed video analysis shows that adhesive contact is both made and broken in intervals of less than 20 ms and this suggests that the mechanism of detachment is one of adhesive instability rather than steady-state peeling. By considering the gecko seta/spatula as a Euler-Bernoulli cantilever it is possible to model this instability in non-dimensional terms and thus to test the analysis at a much larger scale with more conventional engineering materials. When applied to the scale and material combination appropriate to a gecko spatula, the predicted critical load, of around 10 nN, is close to values that have been observed using and AFM cantilever and a single detached spatula.

  14. Adhesional instabilities and gecko locomotion

    International Nuclear Information System (INIS)

    Williams, John A

    2015-01-01

    Geckos possess a remarkable ability to run rapidly on both walls and ceilings and in recent years the mechanisms that underlie this facility have come under close scrutiny. It is now generally agreed that one of the principal mechanisms of adhesion relies on the action of van der Waal forces acting between the final extremely fine structure of the gecko toe and the underlying substrate. High speed video analysis shows that adhesive contact is both made and broken in intervals of less than 20 ms and this suggests that the mechanism of detachment is one of adhesive instability rather than steady-state peeling. By considering the gecko seta/spatula as a Euler–Bernoulli cantilever it is possible to model this instability in non-dimensional terms and thus to test the analysis at a much larger scale with more conventional engineering materials. When applied to the scale and material combination appropriate to a gecko spatula, the predicted critical load, of around 10 nN, is close to values that have been observed using and AFM cantilever and a single detached spatula. (paper)

  15. Ecological Effects of the Invasive Giant Madagascar Day Gecko on Endemic Mauritian Geckos: Applications of Binomial-Mixture and Species Distribution Models

    NARCIS (Netherlands)

    Buckland, S.; Cole, N.C.; Aguirre-Gutiérrez, J.; Gallagher, L.E.; Henshaw, S.M.; Besnard, A.; Tucker, R.M.; Bachraz, V.; Ruhomaun, K.; Harris, S.

    2014-01-01

    The invasion of the giant Madagascar day gecko Phelsuma grandis has increased the threats to the four endemic Mauritian day geckos (Phelsuma spp.) that have survived on mainland Mauritius. We had two main aims: (i) to predict the spatial distribution and overlap of P. grandis and the endemic geckos

  16. Ecological Effects of the Invasive Giant Madagascar Day Gecko on Endemic Mauritian Geckos: Applications of Binomial-Mixture and Species Distribution Models

    OpenAIRE

    Buckland, S.; Cole, N.C.; Aguirre-Gutiérrez, J.; Gallagher, L.E.; Henshaw, S.M.; Besnard, A.; Tucker, R.M.; Bachraz, V.; Ruhomaun, K.; Harris, S.

    2014-01-01

    The invasion of the giant Madagascar day gecko Phelsuma grandis has increased the threats to the four endemic Mauritian day geckos (Phelsuma spp.) that have survived on mainland Mauritius. We had two main aims: (i) to predict the spatial distribution and overlap of P. grandis and the endemic geckos at a landscape level; and (ii) to investigate the effects of P. grandis on the abundance and risks of extinction of the endemic geckos at a local scale. An ensemble forecasting approach was used to...

  17. Testing the phylogenetic affinities of Southeast Asia's rarest geckos: Flap-legged geckos (Luperosaurus), Flying geckos (Ptychozoon) and their relationship to the pan-Asian genus Gekko.

    Science.gov (United States)

    Brown, Rafe M; Siler, Cameron D; Das, Indraneil; Min, Yong

    2012-06-01

    Some of Southeast Asia's most poorly known vertebrates include forest lizards that are rarely seen by field biologists. Arguably the most enigmatic of forest lizards from the Indo Australian archipelago are the Flap-legged geckos and the Flying geckos of the genera Luperosaurus and Ptychozoon. As new species have accumulated, several have been noted for their bizarre combination of morphological characteristics, seemingly intermediate between these genera and the pan-Asian gecko genus Gekko. We used the first multilocus phylogeny for these taxa to estimate their relationships, with particular attention to the phylogenetic placement of the morphologically intermediate taxa Ptychozoon rhacophorus, Luperosaurus iskandari, and L. gulat. Surprisingly, our results demonstrate that Luperosaurus is more closely related to Lepidodactylus and Pseudogekko than it is to Gekko but that some species currently classified as Luperosaurus are nested within Gekko. The Flying Gecko genus Ptychozoon is also nested within Gekko, suggesting that higher-level taxonomic revision of the generic boundaries within Southeast Asian gekkonines will be a priority for the immediate future. Copyright © 2012 Elsevier Inc. All rights reserved.

  18. A new angle on clinging in geckos: incline, not substrate, triggers the deployment of the adhesive system

    Science.gov (United States)

    Russell, Anthony P.; Higham, Timothy E.

    2009-01-01

    Lizards commonly climb in complex three-dimensional habitats, and gekkotans are particularly adept at doing this by using an intricate adhesive system involving setae on the ventral surface of their digits. However, it is not clear whether geckos always deploy their adhesive system, given that doing so may result in decreased (i.e. reduction in speed) locomotor performance. Here, we investigate circumstances under which the adhesive apparatus of clinging geckos becomes operative, and examine the potential trade-offs between speed and clinging. We quantify locomotor kinematics of a gecko with adhesive capabilities (Tarentola mauritanica) and one without (Eublepharis macularius). Whereas, somewhat unusually, E. macularius did not suffer a decrease in locomotor performance with an increase in incline, T. mauritanica exhibited a significant decrease in speed between the level and a 10° incline. We demonstrate that this results from the combined influence of slope and the deployment of the adhesive system. All individuals kept their digits hyperextended on the level, but three of the six individuals deployed their adhesive system on the 10° incline, and they exhibited the greatest decrease in velocity. The deployment of the adhesive system was dependent on incline, not surface texture (600 grit sandpaper and Plexiglas), despite slippage occurring on the level Plexiglas substrate. Our results highlight the type of sensory feedback (gravity) necessary for deployment of the adhesive system, and the trade-offs associated with adhesion. PMID:19656797

  19. Viscoelastic features of adhesive setae of the tokay gecko (Gekko gecko L.).

    Science.gov (United States)

    Ivlev, Yu F; Il'in, A I; Trofimov, O V

    2016-03-01

    Deformations of particular setae of adhesive toe pad of the tokay gecko were investigated by atomic-force microscopy. The effective elastic modulus of the investigated setae varying within 0.34-19 GPa, a pronounced hysteresis was observed during reversible bending of setae. The hysteresis-related energy losses may be as high as 98% of the total bending work. The pronounced viscous features of the setae contradict the hypothesis of dynamic self-cleaning of the gecko adhesive cover, according to which the setae are considered as absolutely elastic cantilever beams.

  20. Evidence for van der Waals adhesion in gecko setae

    OpenAIRE

    Autumn, Kellar; Sitti, Metin; Liang, Yiching A.; Peattie, Anne M.; Hansen, Wendy R.; Sponberg, Simon; Kenny, Thomas W.; Fearing, Ronald; Israelachvili, Jacob N.; Full, Robert J.

    2002-01-01

    Geckos have evolved one of the most versatile and effective adhesives known. The mechanism of dry adhesion in the millions of setae on the toes of geckos has been the focus of scientific study for over a century. We provide the first direct experimental evidence for dry adhesion of gecko setae by van der Waals forces, and reject the use of mechanisms relying on high surface polarity, including capillary adhesion. The toes of live Tokay geckos were highly hydrophobic, and adhered equally well ...

  1. Observation of optimal gecko's adhesion on nanorough surfaces.

    Science.gov (United States)

    Pugno, Nicola M; Lepore, Emiliano

    2008-12-01

    In this letter we report experimental observations on the times of adhesion of living Tokay geckos (Gekko geckos) on polymethylmethacrylate (PMMA) inverted surfaces. Two different geckos (male and female) and three surfaces with different root mean square (RMS) roughness (RMS=42, 618 and 931 nm) have been considered, for a total of 72 observations. The measured data are proved to be statistically significant, following the Weibull Statistics with coefficients of correlation between 0.781 and 0.955. The unexpected result is the observation of a maximal gecko adhesion on the surface with intermediate roughness of RMS=618 nm, that we note has waviness comparable to the seta size.

  2. Evidence for self-cleaning in gecko setae

    Science.gov (United States)

    Hansen, W. R.; Autumn, K.

    2005-01-01

    A tokay gecko can cling to virtually any surface and support its body mass with a single toe by using the millions of keratinous setae on its toe pads. Each seta branches into hundreds of 200-nm spatulae that make intimate contact with a variety of surface profiles. We showed previously that the combined surface area of billions of spatulae maximizes van der Waals interactions to generate large adhesive and shear forces. Geckos are not known to groom their feet yet retain their stickiness for months between molts. How geckos manage to keep their feet clean while walking about with sticky toes has remained a puzzle until now. Although self-cleaning by water droplets occurs in plant and animal surfaces, no adhesive has been shown to self-clean. In the present study, we demonstrate that gecko setae are a self-cleaning adhesive. Geckos with dirty feet recovered their ability to cling to vertical surfaces after only a few steps. Self-cleaning occurred in arrays of setae isolated from the gecko. Contact mechanical models suggest that self-cleaning occurs by an energetic disequilibrium between the adhesive forces attracting a dirt particle to the substrate and those attracting the same particle to one or more spatulae. We propose that the property of self-cleaning is intrinsic to the setal nanostructure and therefore should be replicable in synthetic adhesive materials in the future. adhesion | contact mechanics | locomotion | reptilia | nanotechnology

  3. Sliding Adhesion Dynamics of Isolated Gecko Setal Arrays

    Science.gov (United States)

    Sponberg, Simon; Autumn, Kellar

    2003-03-01

    The tokay gecko (Gekko gecko) can adhere to nearly any surface through van der Waals interactions of the specialized setae (b-keratin "hairs") of its toe pads. Our recent research has suggested that a gecko is substantially overbuilt for static adhesion requiring as little as 0.03of its theoretical adhesive capacity. We performed the first sliding adhesion experiments on this novel biological adhesive to determine its response to dynamic loading. We isolated arrays of setae and constructed a precision controlled Robo-toe to study sliding effects. Our results indicate that, unlike many typical adhesives, gecko setal arrays exhibit an increased frictional force upon sliding (mk > ms) which further increases with velocity, suggesting that perturbation rejection may be an evolutionary design principle underlying the evolution of the gecko adhesive. We compare these dynamic properties with those of other adhesives and explore the impacts of these results on the design of artificial adhesives.

  4. Peramorphic traits in the tokay gecko skull.

    Science.gov (United States)

    Daza, Juan D; Mapps, Aurelia A; Lewis, Patrick J; Thies, Monte L; Bauer, Aaron M

    2015-08-01

    Traditionally, geckos have been conceived to exhibit paedomorphic features relative to other lizards (e.g., large eyes, less extensively ossified skulls, and amphicoelous and notochordal vertebrae). In contrast, peramorphosis has not been considered an important process in shaping their morphology. Here, we studied different sized specimens of Gekko gecko to document ontogenetic changes in cranial anatomy, especially near maturity. Comparison of this species with available descriptions of other geckos resulted in the identification of 14 cranial characteristics that are expressed more strongly with size increase. These characteristics become move evident in later stages of post-hatching development, especially near maturation, and are, therefore, attributed to peramorphosis (hyperossification). ACCTRAN and DELTRAN character optimizations were applied to these characters using a tree of 11 genera derived from a gekkotan molecular phylogeny. This analysis revealed that G. gecko expresses the majority of these putative peramorphic features near maturity, and that some of these features are also expressed in species closely related to G. gecko. The characters studied have the potential to be applied in future phylogenetic and taxonomic studies of this group of lizards. © 2015 Wiley Periodicals, Inc.

  5. Draft genome of the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Xiong, Zijun; Li, Fang; Li, Qiye; Zhou, Long; Gamble, Tony; Zheng, Jiao; Kui, Ling; Li, Cai; Li, Shengbin; Yang, Huanming; Zhang, Guojie

    2016-10-26

    Geckos are among the most species-rich reptile groups and the sister clade to all other lizards and snakes. Geckos possess a suite of distinctive characteristics, including adhesive digits, nocturnal activity, hard, calcareous eggshells, and a lack of eyelids. However, one gecko clade, the Eublepharidae, appears to be the exception to most of these 'rules' and lacks adhesive toe pads, has eyelids, and lays eggs with soft, leathery eggshells. These differences make eublepharids an important component of any investigation into the underlying genomic innovations contributing to the distinctive phenotypes in 'typical' geckos. We report high-depth genome sequencing, assembly, and annotation for a male leopard gecko, Eublepharis macularius (Eublepharidae). Illumina sequence data were generated from seven insert libraries (ranging from 170 to 20 kb), representing a raw sequencing depth of 136X from 303 Gb of data, reduced to 84X and 187 Gb after filtering. The assembled genome of 2.02 Gb was close to the 2.23 Gb estimated by k-mer analysis. Scaffold and contig N50 sizes of 664 and 20 kb, respectively, were comparable to the previously published Gekko japonicus genome. Repetitive elements accounted for 42 % of the genome. Gene annotation yielded 24,755 protein-coding genes, of which 93 % were functionally annotated. CEGMA and BUSCO assessment showed that our assembly captured 91 % (225 of 248) of the core eukaryotic genes, and 76 % of vertebrate universal single-copy orthologs. Assembly of the leopard gecko genome provides a valuable resource for future comparative genomic studies of geckos and other squamate reptiles.

  6. Superhydrophobic gecko feet with high adhesive forces towards water and their bio-inspired materials

    Science.gov (United States)

    Liu, Kesong; Du, Jiexing; Wu, Juntao; Jiang, Lei

    2012-01-01

    Functional integration is an inherent characteristic for multiscale structures of biological materials. In this contribution, we first investigate the liquid-solid adhesive forces between water droplets and superhydrophobic gecko feet using a high-sensitivity micro-electromechanical balance system. It was found, in addition to the well-known solid-solid adhesion, the gecko foot, with a multiscale structure, possesses both superhydrophobic functionality and a high adhesive force towards water. The origin of the high adhesive forces of gecko feet to water could be attributed to the high density nanopillars that contact the water. Inspired by this, polyimide films with gecko-like multiscale structures were constructed by using anodic aluminum oxide templates, exhibiting superhydrophobicity and a strong adhesive force towards water. The static water contact angle is larger than 150° and the adhesive force to water is about 66 μN. The resultant gecko-inspired polyimide film can be used as a ``mechanical hand'' to snatch micro-liter liquids. We expect this work will provide the inspiration to reveal the mechanism of the high-adhesive superhydrophobic of geckos and extend the practical applications of polyimide materials.

  7. Does the mechanism of sex determination constrain the potential for sex manipulation? A test in geckos with contrasting sex-determining systems

    Science.gov (United States)

    Kratochvíl, Lukáš; Kubička, Lukáš; Landová, Eva

    2008-03-01

    The concentration of yolk steroids was suggested to influence offspring gender in oviparous animals subject to both temperature-dependent sex determination (TSD) and genotypic sex determination (GSD). However, the proposed mechanisms of steroid effects are thought to differ between TSD and GSD: a direct effect of oestrogens on gonad feminisation in TSD species vs a differential induction of male-producing or female-producing gametes in GSD species. Geckos offer an ideal opportunity for testing these suggested mechanisms. Closely related gecko species differ in their modes of sex determination. They lay clutches of two synchronously formed eggs; both eggs share equal steroid levels. If identical hormonal composition and environment during vitellogenesis, gravidity and incubation determine the sex of the progeny, siblings should share the same gender in both TSD and GSD geckos. We found strong support for this prediction in a TSD gecko species. Among clutches that were incubated at the temperature that produced both sexes, there were no clutches with siblings of the opposite sex. On the other hand, about half of the clutches yielded siblings of the opposite sex in four GSD species. These results suggest that sex-determining systems constrain the ability of the female to produce single-sex siblings and, hence, it seems that the GSD mechanism constrains the opportunities for sex ratio manipulation in geckos via yolk steroid manipulation.

  8. Draft genome of the leopard gecko, Eublepharis macularius

    OpenAIRE

    Xiong, Zijun; Li, Fang; Li, Qiye; Zhou, Long; Gamble, Tony; Zheng, Jiao; Kui, Ling; Li, Cai; Li, Shengbin; Yang, Huanming; Zhang, Guojie

    2016-01-01

    Background Geckos are among the most species-rich reptile groups and the sister clade to all other lizards and snakes. Geckos possess a suite of distinctive characteristics, including adhesive digits, nocturnal activity, hard, calcareous eggshells, and a lack of eyelids. However, one gecko clade, the Eublepharidae, appears to be the exception to most of these ?rules? and lacks adhesive toe pads, has eyelids, and lays eggs with soft, leathery eggshells. These differences make eublepharids an i...

  9. Genetic diversity of the red-spotted tokay gecko (Gekko gecko Linnaeus, 1758) (Squamata: Gekkonidae) in Southeast Asia determined with multilocus enzyme electrophoresis

    OpenAIRE

    Watee Kongbuntad; Chairat Tantrawatpan; Warayutt Pilap; Kamonwan Jongsomchai; Tawin Chanaboon; Panida Laotongsan; Trevor N. Petney; Weerachai Saijuntha

    2016-01-01

    Red-spotted tokay geckos, Gekko gecko, are distributed mainly in Southeast Asia. They are a traditional Chinese medicine, with the massive hunting for exports dramatically decreasing their numbers. Information on the genetic diversity of these geckos in Southeast Asia is very limited. This study aims to explore intrapopulation and interpopulation genetic variation and the genetic structure of 16 populations collected from different localities in Thailand, Lao People’s Democratic Republic, and...

  10. Self-drying: a gecko's innate ability to remove water from wet toe pads.

    Directory of Open Access Journals (Sweden)

    Alyssa Y Stark

    Full Text Available When the adhesive toe pads of geckos become wet, they become ineffective in enabling geckos to stick to substrates. This result is puzzling given that many species of gecko are endemic to tropical environments where water covered surfaces are ubiquitous. We hypothesized that geckos can recover adhesive capabilities following exposure of their toe pads to water by walking on a dry surface, similar to the active self-cleaning of dirt particles. We measured the time it took to recover maximum shear adhesion after toe pads had become wet in two groups, those that were allowed to actively walk and those that were not. Keeping in mind the importance of substrate wettability to adhesion on wet surfaces, we also tested geckos on hydrophilic glass and an intermediately wetting substrate (polymethylmethacrylate; PMMA. We found that time to maximum shear adhesion recovery did not differ in the walking groups based on substrate wettability (22.7±5.1 min on glass and 15.4±0.3 min on PMMA but did have a significant effect in the non-walking groups (54.3±3.9 min on glass and 27.8±2.5 min on PMMA. Overall, we found that by actively walking, geckos were able to self-dry their wet toe pads and regain maximum shear adhesion significantly faster than those that did not walk. Our results highlight a unexpected property of the gecko adhesive system, the ability to actively self-dry and recover adhesive performance after being rendered dysfunctional by water.

  11. Sticky gecko feet: the role of temperature and humidity.

    Directory of Open Access Journals (Sweden)

    Peter H Niewiarowski

    Full Text Available Gecko adhesion is expected to be temperature insensitive over the range of temperatures typically experienced by geckos. Previous work is limited and equivocal on whether this expectation holds. We tested the temperature dependence of adhesion in Tokay and Day geckos and found that clinging ability at 12 degrees C was nearly double the clinging ability at 32 degrees C. However, rather than confirming a simple temperature effect, our data reveal a complex interaction between temperature and humidity that can drive differences in adhesion by as much as two-fold. Our findings have important implications for inferences about the mechanisms underlying the exceptional clinging capabilities of geckos, including whether performance of free-ranging animals is based solely on a dry adhesive model. An understanding of the relative contributions of van der Waals interactions and how humidity and temperature variation affects clinging capacities will be required to test hypotheses about the evolution of gecko toepads and is relevant to the design and manufacture of synthetic mimics.

  12. Sticky gecko feet: the role of temperature and humidity.

    Science.gov (United States)

    Niewiarowski, Peter H; Lopez, Stephanie; Ge, Liehui; Hagan, Emily; Dhinojwala, Ali

    2008-05-14

    Gecko adhesion is expected to be temperature insensitive over the range of temperatures typically experienced by geckos. Previous work is limited and equivocal on whether this expectation holds. We tested the temperature dependence of adhesion in Tokay and Day geckos and found that clinging ability at 12 degrees C was nearly double the clinging ability at 32 degrees C. However, rather than confirming a simple temperature effect, our data reveal a complex interaction between temperature and humidity that can drive differences in adhesion by as much as two-fold. Our findings have important implications for inferences about the mechanisms underlying the exceptional clinging capabilities of geckos, including whether performance of free-ranging animals is based solely on a dry adhesive model. An understanding of the relative contributions of van der Waals interactions and how humidity and temperature variation affects clinging capacities will be required to test hypotheses about the evolution of gecko toepads and is relevant to the design and manufacture of synthetic mimics.

  13. Coming to America: multiple origins of New World geckos.

    Science.gov (United States)

    Gamble, T; Bauer, A M; Colli, G R; Greenbaum, E; Jackman, T R; Vitt, L J; Simons, A M

    2011-02-01

    Geckos in the Western Hemisphere provide an excellent model to study faunal assembly at a continental scale. We generated a time-calibrated phylogeny, including exemplars of all New World gecko genera, to produce a biogeographical scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographical scenario utilized by a terrestrial vertebrate with different New World lineages showing evidence of vicariance, dispersal via temporary land bridge, overseas dispersal or anthropogenic introductions. We also recovered a strong relationship between clade age and species diversity, with older New World lineages having more species than more recently arrived lineages. Our data provide the first phylogenetic hypothesis for all New World geckos and highlight the intricate origins and ongoing organization of continental faunas. The phylogenetic and biogeographical hypotheses presented here provide an historical framework to further pursue research on the diversification and assembly of the New World herpetofauna. © 2010 The Authors. Journal of Evolutionary Biology © 2010 European Society For Evolutionary Biology.

  14. Effect of Tokay Gecko (Gekko Gecko LINNAEUS, 1758) Saliva on Angiogenesis During Wound Healing Phase of Autotomized Tail in Common Sun Skink (Eutropis Multifasciata KUHL, 1820)

    OpenAIRE

    Inayah, Nurul; Soesilo, Nyoman Puniawati; Pratiwi, Rarastoeti

    2017-01-01

    The purpose of this study was to investigate the effect of Tokay gecko saliva on morphology and angiogenesis response on the healing process of skink tail wound and also to characterize the protein profile of Gecko saliva. Twelve skinks were autotomized and wound surface of tail smeared by young gecko saliva, adult gecko saliva, and human's saliva twice per day and control. The morphological changes of the wound surface were observed. The angiogenesis response was observed in vitro using Chor...

  15. Human climbing with efficiently scaled gecko-inspired dry adhesives

    OpenAIRE

    Hawkes, Elliot W.; Eason, Eric V.; Christensen, David L.; Cutkosky, Mark R.

    2015-01-01

    Since the discovery of the mechanism of adhesion in geckos, many synthetic dry adhesives have been developed with desirable gecko-like properties such as reusability, directionality, self-cleaning ability, rough surface adhesion and high adhesive stress. However, fully exploiting these adhesives in practical applications at different length scales requires efficient scaling (i.e. with little loss in adhesion as area grows). Just as natural gecko adhesives have been used as a benchmark for syn...

  16. Passive Control of Attachment in Legged Space Robots

    Directory of Open Access Journals (Sweden)

    Alessandro Gasparetto

    2010-01-01

    Full Text Available In the space environment the absence of gravity calls for constant safe attachment of any loose object, but the low-pressure conditions prohibit the use of glue-type adhesives. The attachment system of freely hunting spiders, e.g. Evarcha arcuata, employs van der Waals forces and mechanical interlocking. Furthermore, detachment is achieved passively and requires little force. Hence, the spider serves as a model for a versatile legged robot for space applications, e.g. on the outer surface of a space station. In this paper, we analyse the dry attachment systems of E. arcuata and geckos as well as the kinematics of freely hunting spiders. We generalise the results of biological studies on spider locomotion and mobility, including the major movement and the position constraints set by the dry adhesion system. From these results, we define a simplified spider model and study the overall kinematics of the legs both in flight and in contact with the surface. The kinematic model, the data on spider gait characteristics and the adhesion constraints are implemented in a kinematic simulator. The simulator results confirm the principal functionality of our concept.

  17. Proliferative thyroid lesions in three diplodactylid geckos: Nephrurus amyae, Nephrurus levis, and Oedura marmorata.

    Science.gov (United States)

    Hadfield, Catherine A; Clayton, Leigh A; Clancy, Meredith M; Beck, Sarah E; Mangus, Lisa M; Montali, Richard J

    2012-03-01

    Over a 5-mo period, three diplodactylid geckos housed at the National Aquarium were diagnosed with proliferative thyroid lesions: a rough knob-tail gecko (Nephrurus amyae), a smooth knob-tail gecko (Nephrurus levis), and a marbled velvet gecko (Oedura marmorata). Clinical signs included an intraoral mass or ventral throat swelling (or both), oral bleeding, and weight loss. Both of the knob-tail geckos died. The histologic diagnosis for the rough knob-tail gecko was thyroid carcinoma with metastases to the liver and lungs, and thyroid carcinoma with no metastases was reported in the smooth knob-tail gecko. A thyroidectomy was performed on the marbled velvet gecko with a histologic diagnosis of adenomatous hyperplasia. Postoperative weight loss and bradycardia resolved following oral supplementation with levothyroxine. The animal is in normal health 10 mo post-surgery. Five other diplodactylid geckos in the collection remain unaffected, giving a 38% prevalence of proliferative thyroid lesions (3/8). The etiology remains undetermined. This is the first report of a cluster of proliferative thyroid lesions in geckos.

  18. Fabrication and Characterization of Gecko-inspired Fibrillar Adhesive

    Science.gov (United States)

    Kim, Yongkwan

    Over the last decade, geckos' remarkable ability to stick to and climb surfaces found in nature has motivated a wide range of scientific interest in engineering gecko-mimetic surface for various adhesive and high friction applications. The high adhesion and friction of its pads have been attributed to a complex array of hairy structures, which maximize surface area for van der Waals interaction between the toes and the counter-surface. While advances in micro- and nanolithography technique have allowed fabrication of increasingly sophisticated gecko mimetic surfaces, it remains a challenge to produce an adhesive as robust as that of the natural gecko pads. In order to rationally design gecko adhesives, understanding the contact behavior of fibrillar interface is critical. The first chapter of the dissertation introduces gecko adhesion and its potential applications, followed by a brief survey of gecko-inspired adhesives. Challenges that limit the performance of the current adhesives are presented. In particular, it is pointed out that almost all testing of gecko adhesives have been on clean, smooth glass, which is ideal for adhesion due to high surface energy and low roughness. Surfaces in application are more difficult to stick to, so the understanding of failure modes in low energy and rough surfaces is important. The second chapter presents a fabrication method for thermoplastic gecko adhesive to be used for a detailed study of fibrillar interfaces. Low-density polyethylene nanofibers are replicated from a silicon nanowire array fabricated by colloidal lithography and metal-catalyzed chemical etching. This process yields a highly ordered array of nanofibers over a large area with control over fiber diameter, length, and number density. The high yield and consistency of the process make it ideal for a systematic study on factors that affect adhesion and friction of gecko adhesives. The following three chapters examine parameters that affect macroscale friction of

  19. Leaping lizards landing on leaves: escape-induced jumps in the rainforest canopy challenge the adhesive limits of geckos.

    Science.gov (United States)

    Higham, Timothy E; Russell, Anthony P; Niklas, Karl J

    2017-06-01

    The remarkable adhesive capabilities of geckos have garnered attention from scientists and the public for centuries. Geckos are known to have an adhesive load-bearing capacity far in excess (by 100-fold or more) of that required to support their body mass or accommodate the loading imparted during maximal locomotor acceleration. Few studies, however, have investigated the ecological contexts in which geckos use their adhesive system and how this may influence its properties. Here we develop a modelling framework to assess whether their prodigious adhesive capacity ever comes under selective challenge. Our investigation is based upon observations of escape-induced aerial descents of canopy-dwelling arboreal geckos that are rapidly arrested by clinging to leaf surfaces in mid-fall. We integrate ecological observations, adhesive force measurements, and body size and shape measurements of museum specimens to conduct simulations. Using predicted bending mechanics of petioles and leaf midribs, we find that the drag coefficient of the gecko, the size of the gecko and the size of the leaf determine impact forces. Regardless of the landing surface, safety factors for geckos range from a maximum of just over 10 to a minimum of well under one, which would be the point at which the adhesive system fails. In contrast to previous research that intimates that gecko frictional adhesive capacity is excessive relative to body mass, we demonstrate that realistic conditions in nature may result in frictional capacity being pushed to its limit. The rapid arrest of the lizard from its falling velocity likely results in the maximal loading to which the adhesive system is exposed during normal activities. We suggest that such activities might be primary determinants in driving their high frictional adhesive capacity. © 2017 The Author(s).

  20. Purification and low temperature spectroscopy of gecko visual pigments green and blue.

    Science.gov (United States)

    Kojima, D; Imai, H; Okano, T; Fukada, Y; Crescitelli, F; Yoshizawa, T; Shichida, Y

    1995-01-24

    We purified two kinds of visual pigments, gecko green and gecko blue, from retinas of Tokay geckos (Gekko gekko) by two steps of column chromatography, and investigated their photobleaching processes by means of low temperature spectroscopy. Absorption maxima of gecko green and blue solubilized in a mixture of 3-[(3-cholamidopropyl)dimethylammonio]-1- propanesulfonate (CHAPS) and phosphatidylcholine were 522 and 465 nm, respectively, which are close to those observed in the photoreceptor cells. Low temperature spectroscopy identified six intermediates in the photobleaching process of gecko green; batho (lambda max = 569 nm), BL (lambda max = 519 nm), lumi (507 nm), meta I (approximately 486 nm), meta II (approximately 384 nm), and meta III intermediates (approximately 500 nm). In contrast to the high similarity in amino acid sequence between gecko green and iodopsin [Kojima, D., et al. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 6841-6845], the batho-green did not revert thermally to original gecko green but converts to the next intermediate. The photobleaching process of gecko blue was investigated by low temperature spectroscopy, and three intermediates, meta I (lambda max = approximately 470 nm), meta II (lambda max = approximately 370 nm) and meta III (lambda max = approximately 475 nm), were identified. A comparative study on the thermal behavior of meta intermediates revealed that the thermal stability of meta II intermediate of both of the gecko visual pigments is lower than that of metarhodopsin II. The result supports the idea that both the gecko visual pigments are cone-type ones.

  1. The carriage of antibiotic resistance by enteric bacteria from imported tokay geckos (Gekko gecko) destined for the pet trade

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Christine L. [Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States); Hernandez, Sonia M., E-mail: shernz@uga.edu [Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States); Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602 (United States); Yabsley, Michael J. [Southeastern Cooperative Wildlife Disease Study, Department of Population Health, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States); Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA 30602 (United States); Smith, Katherine F. [Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912 (United States); Sanchez, Susan [The Athens Veterinary Diagnostic Laboratory, Athens, GA 30602 (United States); The Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, GA 30602 (United States)

    2015-02-01

    The emergence of antibiotic-resistant bacteria is a growing public health concern and has serious implications for both human and veterinary medicine. The nature of the global economy encourages the movement of humans, livestock, produce, and wildlife, as well as their potentially antibiotic-resistant bacteria, across international borders. Humans and livestock can be reservoirs for antibiotic-resistant bacteria; however, little is known about the prevalence of antibiotic-resistant bacteria harbored by wildlife and, to our knowledge, limited data has been reported for wild-caught reptiles that were specifically collected for the pet trade. In the current study, we examined the antibiotic resistance of lactose-positive Enterobacteriaceae isolates from wild-caught Tokay geckos (Gekko gecko) imported from Indonesia for use in the pet trade. In addition, we proposed that the conditions under which wild animals are captured, transported, and handled might affect the shedding or fecal prevalence of antibiotic resistance. In particular we were interested in the effects of density; to address this, we experimentally modified densities of geckos after import and documented changes in antibiotic resistance patterns. The commensal enteric bacteria from Tokay geckos (G. gecko) imported for the pet trade displayed resistance against some antibiotics including: ampicillin, amoxicillin/clavulanic acid, cefoxitin, chloramphenicol, kanamycin and tetracycline. There was no significant difference in the prevalence of antibiotic-resistant bacteria after experimentally mimicking potentially stressful transportation conditions reptiles experience prior to purchase. There were, however, some interesting trends observed when comparing Tokay geckos housed individually and those housed in groups. Understanding the prevalence of antibiotic resistant commensal enteric flora from common pet reptiles is paramount because of the potential for humans exposed to these animals to acquire antibiotic

  2. The carriage of antibiotic resistance by enteric bacteria from imported tokay geckos (Gekko gecko) destined for the pet trade

    International Nuclear Information System (INIS)

    Casey, Christine L.; Hernandez, Sonia M.; Yabsley, Michael J.; Smith, Katherine F.; Sanchez, Susan

    2015-01-01

    The emergence of antibiotic-resistant bacteria is a growing public health concern and has serious implications for both human and veterinary medicine. The nature of the global economy encourages the movement of humans, livestock, produce, and wildlife, as well as their potentially antibiotic-resistant bacteria, across international borders. Humans and livestock can be reservoirs for antibiotic-resistant bacteria; however, little is known about the prevalence of antibiotic-resistant bacteria harbored by wildlife and, to our knowledge, limited data has been reported for wild-caught reptiles that were specifically collected for the pet trade. In the current study, we examined the antibiotic resistance of lactose-positive Enterobacteriaceae isolates from wild-caught Tokay geckos (Gekko gecko) imported from Indonesia for use in the pet trade. In addition, we proposed that the conditions under which wild animals are captured, transported, and handled might affect the shedding or fecal prevalence of antibiotic resistance. In particular we were interested in the effects of density; to address this, we experimentally modified densities of geckos after import and documented changes in antibiotic resistance patterns. The commensal enteric bacteria from Tokay geckos (G. gecko) imported for the pet trade displayed resistance against some antibiotics including: ampicillin, amoxicillin/clavulanic acid, cefoxitin, chloramphenicol, kanamycin and tetracycline. There was no significant difference in the prevalence of antibiotic-resistant bacteria after experimentally mimicking potentially stressful transportation conditions reptiles experience prior to purchase. There were, however, some interesting trends observed when comparing Tokay geckos housed individually and those housed in groups. Understanding the prevalence of antibiotic resistant commensal enteric flora from common pet reptiles is paramount because of the potential for humans exposed to these animals to acquire antibiotic

  3. Passive Cushiony Biomechanics of Head Protection in Falling Geckos

    OpenAIRE

    Wang, Hao; Wang, Wenbo; Song, Yi; Cai, Lei; Dai, Zhendong

    2018-01-01

    Gekko geckos are capable to crawl on the steep even on upside-down surfaces. Such movement, especially at great altitude, puts them at high risks of incidentally dropping down and inevitable body or head impactions, though they may trigger air-righting reaction (ARR) to attenuate the landing shocks. However, the air-righting ability (ARA) in Gekko geckos is not fully developed. The implementation of ARR in some geckos is quite slow; and for those without tails, the ARR is even unobservable. S...

  4. A forebrain atlas of the lizard Gekko gecko.

    Science.gov (United States)

    Smeets, W J; Hoogland, P V; Lohman, A H

    1986-12-01

    An atlas of the forebrain of the lizard Gekko gecko has been provided, which will serve as the basis for subsequent experimental tracing and immunohistochemical studies. Apart from a strongly developed medial cortex and septal area, the Tokay gecko shows all the main features of the forebrain of the lacertid-type lizards. When its convenience as an experimental animal is also taken into account, this species seems to be very suitable for studying the limbic system in reptiles. The atlas comprises topographical reconstructions of the telencephalon and diencephalon and a series of transverse sections of which the levels have been indicated in the reconstructions. The results obtained in the Gekko are briefly compared with those found in other lizards studied.

  5. Genetic variability of the tokay gecko based on mitochondrial and nuclear DNA.

    Science.gov (United States)

    Wang, Gaochao; Gong, Shu; Jiang, Lichun; Peng, Rui; Shan, Xiang; Zou, Dandan; Yang, Chengzhong; Zou, Fangdong

    2013-10-01

    With largely allopatric distribution, the black tokay and the red tokay are two distinct morphs of the subspecies Gekko gecko gecko. In consideration of their different morphological characteristics, the taxonomic status of G. g. gecko is disputed. Through detailed morphological comparison, it has been proposed that the black tokay should be elevated to species ranking, but without strong genetic evidence. In order to further investigate the taxonomic status of the tokay gecko (G. gecko), we used one mitochondrial marker (ND2) and three nuclear markers (RAG1, c-mos, and ITS2) to explore the phylogenetic and taxonomic relationship of the tokay gecko. Our results revealed a deep phylogeographical divergence in tokay gecko and at the same time provided us with the evidence of possible introgressive hybridization or/and incomplete lineage sorting between the black tokay and the red tokay. The elevation of the black tokay to species level is also supported by our results. However, due to limited sampling and genetic data, this elevation should be further corroborated by more genetic evidence.

  6. Proliferative enteritis in leopard geckos (Eublepharis macularius) associated with Cryptosporidium sp. infection.

    Science.gov (United States)

    Terrell, Scott P; Uhl, Elizabeth W; Funk, Richard S

    2003-03-01

    Twenty-three leopard geckos (Eublepharis macularius) with various clinical histories of weight loss, anorexia, lethargy, and diarrhea were submitted either intact or as biopsy specimens to the University of Florida Anatomic Pathology Service. Gross necropsy findings in the intact geckos included marked reduction of subcutaneous adipose tissue stores at the tail base and mild thickening and reddening of the small intestine. Histologic examination revealed Cryptosporidium sp. infection associated with hyperplasia and mononuclear inflammation of the small intestine in all geckos. Parasites and lesions were only rarely observed in the stomach and large intestine of geckos. The histologic and ultrastructural lesions in the small intestine of leopard geckos infected with Cryptosporidium sp. have not been well characterized previously. This report implicates Cryptosporidium sp. as the cause of disease in the geckos and describes the range of histologic lesions observed.

  7. Gecko adhesion pad: a smart surface?

    Science.gov (United States)

    Pesika, Noshir S.; Zeng, Hongbo; Kristiansen, Kai; Zhao, Boxin; Tian, Yu; Autumn, Kellar; Israelachvili, Jacob

    2009-11-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  8. Gecko adhesion pad: a smart surface?

    International Nuclear Information System (INIS)

    Pesika, Noshir S; Zeng Hongbo; Kristiansen, Kai; Israelachvili, Jacob; Zhao, Boxin; Tian Yu; Autumn, Kellar

    2009-01-01

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  9. Salmonella isolates from wild-caught Tokay geckos (Gekko gecko) imported to the U.S. from Indonesia.

    Science.gov (United States)

    Smith, Katherine F; Yabsley, Michael J; Sanchez, Susan; Casey, Christine L; Behrens, Michael D; Hernandez, Sonia M

    2012-07-01

    Reptiles account for ∼10% of live animal shipments imported to the United States (U.S.), the majority of which are sold in the pet trade. Characterizing Salmonella shedding by imported reptiles is of value to public health, the pet industry, and veterinary medicine. Here we report results of a pilot survey of Salmonella serotypes isolated from wild-caught Indonesian Tokay geckos (Gekko gecko) imported to the U.S. Upon arrival, the geckos were individually housed until a fecal sample was acquired for Salmonella culture. The geckos were divided into three groups with variable numbers to investigate density effects. A second group was imported after 3 months and combined with the previous groups. A total of 88 Salmonella isolates were obtained from 110 geckos surveyed, representing 14 serogroups and 17 unique serotypes. Group prevalence ranged from 31-73%. A significant increase in prevalence and a change in serotype richness were detected between the time of import and 6 months later at necropsy. Six isolates (6.8%) expressed resistance to more than one antibiotic. All S. enterica subsp. enterica Adelaide isolates were resistant to nalidixic acid and sulfisoxazole, one S. enterica subsp. arizonae 61:k:z35 isolate was resistant to ampicillin and sulfisoxazole, and another 61:k:z35 isolate was resistant to streptomycin and sulfisoxazole. Forty-three additional isolates expressed resistance only to sulfisoxazole. The mechanisms for increased prevalence and apparent change in serotype richness are unknown, but could be due to stress associated with trade, transport, and captivity, increased transmission from unnaturally high densities, or contact with other species shedding Salmonella along the trade route. Future studies to differentiate the physical, social, and physiological effects of trade-related conditions on Salmonella shedding and transmission among reptiles will benefit the industry by identifying ways to reduce mortality, and safeguard the individuals

  10. A Review of Sex Determining Mechanisms in Geckos (Gekkota: Squamata)

    Science.gov (United States)

    Gamble, T.

    2010-01-01

    Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanisms with parsimony-based ancestral state reconstruction. While only a small number of gecko species have been characterized, numerous changes among sex determining mechanisms were inferred. This diversity, coupled with the high frequency of transitions, makes geckos excellent candidates as a model clade for the study of vertebrate sex determination and evolution. PMID:20234154

  11. Gecko adhesion pad: a smart surface?

    Energy Technology Data Exchange (ETDEWEB)

    Pesika, Noshir S [Chemical and Biomolecular Engineering Department, Tulane University, New Orleans, LA 70118 (United States); Zeng Hongbo [Chemical and Materials Engineering Department, University of Alberta, Edmonton, AB, T6G 2V4 (Canada); Kristiansen, Kai; Israelachvili, Jacob [Chemical Engineering Department, University of California, Santa Barbara, CA 93117 (United States); Zhao, Boxin [Chemical Engineering Department and Waterloo Institute of Nanotechnology, University of Waterloo, Ontario, N2L 3G1 (Canada); Tian Yu [State Key Laboratory of Tribology, Department of Precision Instruments, Tsinghua University, Beijing 100084 (China); Autumn, Kellar, E-mail: npesika@tulane.ed [Department of Biology, Lewis and Clark College, Portland, OR 97219 (United States)

    2009-11-18

    Recently, it has been shown that humidity can increase the adhesion of the spatula pads that form the outermost (adhesive) surface of the tokay gecko feet by 50% relative to the main adhesion mechanism (i.e. van der Waals adhesive forces), although the mechanism by which the enhancement is realized is still not well understood. A change in the surface hydrophobicity of a gecko setal array is observed when the array, which supports the spatulae, is exposed to a water drop for more than 20 min, suggesting a change in the hydrophilic-lyophilic balance (HLB), and therefore of the conformation of the surface proteins. A surface force apparatus (SFA) was used to quantify these changes, i.e. in the adhesion and friction forces, while shearing the setal array against a silica surface under (i) dry conditions, (ii) 100% humidity and (iii) when fully immersed in water. The adhesion increased in the humid environment but greatly diminished in water. Although the adhesion forces changed significantly, the friction forces remained unaffected, indicating that the friction between these highly textured surfaces is 'load-controlled' rather than 'adhesion-controlled'. These results demonstrate that the gecko adhesive pads have the ability to exploit environmental conditions to maximize their adhesion and stabilize their friction forces. Future designs of synthetic dry adhesives inspired by the gecko can potentially include similar 'smart' surfaces that adapt to their environment.

  12. Hyperimmune bovine colostrum treatment of moribund Leopard geckos (Eublepharis macularius) infected with Cryptosporidium sp.

    Science.gov (United States)

    Graczyk, T K; Cranfield, M R; Bostwick, E F

    1999-01-01

    Therapy based on the protective passive immunity of hyperimmune bovine colostrum (HBC) was applied to 12 moribund Leopard geckos (Eublepharis macularius) infected with Cryptosporidium sp. The geckos were lethargic and moderately to severely emaciated, weighing on average 36% of the baseline body weight value. Seven gastric HBC treatments at 1-week intervals each decreased the relative output of Cryptosporidium sp. oocysts and the prevalence of oocyst-positive fecal specimens. Histologically, after 8 weeks of therapy, seven out of 12 geckos had only single developmental stages of Cryptosporidium sp. in the intestinal epithelium, and three, one and one geckos had low, moderate and high numbers, respectively, of the pathogen developmental stages. The HBC therapy was efficacious in decreasing the parasite load in moribund geckos. Morphometric and immunologic analysis of Cryptosporidium sp. oocyst isolates originating from Leopard geckos (E. macularius) demonstrated differences between gecko-derived oocyst isolates and isolates of C. serpentis recovered from snakes.

  13. Three Species of Ectoparasite Mites (Acari: Pterygosomatidae Infested Geckos in Indonesia

    Directory of Open Access Journals (Sweden)

    TARUNI SRI PRAWASTI

    2013-06-01

    Full Text Available Limited data is hitherto available on the diversity and dispersal of parasitic mites of geckos in Indonesia. Here, we collected three species of geckos, namely Cosymbotus platyurus, Hemidactylus frenatus, and H. garnotii throughout Indonesia to study the distribution and diversity of its parasitic mites. We conducted detail morphological analysis of the mites using whole mount polyvinyl lactophenol and scanning electron microscope preparation. Three species of ectoparasite mites from genus Geckobia were identified in a total of 221 individuals out of 448 geckos collected from 25 sites in Indonesia. Two species were G. glebosum and G. bataviensis, and the other one was designated as Geckobia sp 1. Based on our result, the three mites species were spread randomly and live sympatrically. The G. bataviensis mite showed the widest distribution, because it was found in almost all gecko collection sites, hence the most cosmopolitan mites. We also found that C. platyurus gecko had the lowest mite prevalence which might due to the fact that it has the least number of skin folds, an important site for mite protection. This result implies that further research on the relationship of anatomy of gecko skin with chelicera and claw structure of mites is necessary in the future.

  14. Sticking to the story: outstanding challenges in gecko-inspired adhesives.

    Science.gov (United States)

    Niewiarowski, Peter H; Stark, Alyssa Y; Dhinojwala, Ali

    2016-04-01

    The natural clinging ability of geckos has inspired hundreds of studies seeking design principles that could be applied to creating synthetic adhesives with the same performance capabilities as the gecko: adhesives that use no glue, are self-cleaning and reusable, and are insensitive to a wide range of surface chemistries and roughness. Important progress has been made, and the basic mechanics of how 'hairy' adhesives work have been faithfully reproduced, advancing theory in surface science and portending diverse practical applications. However, after 15 years, no synthetic mimic can yet perform as well as a gecko and simultaneously meet of all the criteria listed above. Moreover, processes for the production of inexpensive and scalable products are still not clearly in view. Here, we discuss our perspective on some of the gaps in understanding that still remain; these gaps in our knowledge should stimulate us to turn to deeper study of the way in which free-ranging geckos stick to the variety of surfaces found in their natural environments and to a more complete analysis of the materials composing the gecko toe pads. © 2016. Published by The Company of Biologists Ltd.

  15. Physiological Status Drives Metabolic Rate in Mediterranean Geckos Infected with Pentastomes.

    Directory of Open Access Journals (Sweden)

    Isabel C Caballero

    Full Text Available Negative effects of parasites on their hosts are well documented, but the proximate mechanisms by which parasites reduce their host's fitness are poorly understood. For example, it has been suggested that parasites might be energetically demanding. However, a recent meta-analysis suggests that they have statistically insignificant effects on host resting metabolic rate (RMR. It is possible, though, that energetic costs associated with parasites are only manifested during and/or following periods of activity. Here, we measured CO2 production (a surrogate for metabolism in Mediterranean geckos (Hemidactylus turcicus infected with a lung parasite, the pentastome Raillietiella indica, under two physiological conditions: rested and recently active. In rested geckos, there was a negative, but non-significant association between the number of pentastomes (i.e., infection intensity and CO2 production. In recently active geckos (chased for 3 minutes, we recorded CO2 production from its maximum value until it declined to a stationary phase. We analyzed this decline as a 3 phase function (initial decline, secondary decline, stationary. Geckos that were recently active showed, in the secondary phase, a significant decrease in CO2 production as pentastome intensity increased. Moreover, duration of the secondary phase showed a significant positive association with the number of pentastomes. These results suggest that the intensity of pentastome load exerts a weak effect on the metabolism of resting geckos, but a strong physiological effect on geckos that have recently been active; we speculate this occurs via mechanical constraints on breathing. Our results provide a potential mechanism by which pentastomes can reduce gecko fitness.

  16. Physiological Status Drives Metabolic Rate in Mediterranean Geckos Infected with Pentastomes.

    Science.gov (United States)

    Caballero, Isabel C; Sakla, Andrew J; Detwiler, Jillian T; Le Gall, Marion; Behmer, Spencer T; Criscione, Charles D

    2015-01-01

    Negative effects of parasites on their hosts are well documented, but the proximate mechanisms by which parasites reduce their host's fitness are poorly understood. For example, it has been suggested that parasites might be energetically demanding. However, a recent meta-analysis suggests that they have statistically insignificant effects on host resting metabolic rate (RMR). It is possible, though, that energetic costs associated with parasites are only manifested during and/or following periods of activity. Here, we measured CO2 production (a surrogate for metabolism) in Mediterranean geckos (Hemidactylus turcicus) infected with a lung parasite, the pentastome Raillietiella indica, under two physiological conditions: rested and recently active. In rested geckos, there was a negative, but non-significant association between the number of pentastomes (i.e., infection intensity) and CO2 production. In recently active geckos (chased for 3 minutes), we recorded CO2 production from its maximum value until it declined to a stationary phase. We analyzed this decline as a 3 phase function (initial decline, secondary decline, stationary). Geckos that were recently active showed, in the secondary phase, a significant decrease in CO2 production as pentastome intensity increased. Moreover, duration of the secondary phase showed a significant positive association with the number of pentastomes. These results suggest that the intensity of pentastome load exerts a weak effect on the metabolism of resting geckos, but a strong physiological effect on geckos that have recently been active; we speculate this occurs via mechanical constraints on breathing. Our results provide a potential mechanism by which pentastomes can reduce gecko fitness.

  17. Effective elastic modulus of isolated gecko setal arrays.

    Science.gov (United States)

    Autumn, K; Majidi, C; Groff, R E; Dittmore, A; Fearing, R

    2006-09-01

    Conventional pressure sensitive adhesives (PSAs) are fabricated from soft viscoelastic materials that satisfy Dahlquist's criterion for tack with a Young's modulus (E) of 100 kPa or less at room temperature and 1 Hz. In contrast, the adhesive on the toes of geckos is made of beta-keratin, a stiff material with E at least four orders of magnitude greater than the upper limit of Dahlquist's criterion. Therefore, one would not expect a beta-keratin structure to function as a PSA by deforming readily to make intimate molecular contact with a variety of surface profiles. However, since the gecko adhesive is a microstructure in the form of an array of millions of high aspect ratio shafts (setae), the effective elastic modulus (E(eff)) is much lower than E of bulk beta-keratin. In the first test of the E(eff) of a gecko setal adhesive, we measured the forces resulting from deformation of isolated arrays of tokay gecko (Gekko gecko) setae during vertical compression, and during tangential compression at angles of +45 degrees and -45 degrees . We tested the hypothesis that E(eff) of gecko setae falls within Dahlquist's criterion for tack, and evaluated the validity of a model of setae as cantilever beams. Highly linear forces of deformation under all compression conditions support the cantilever model. E(eff) of setal arrays during vertical and +45 degrees compression (along the natural path of drag of the setae) were 83+/-4.0 kPa and 86+/-4.4 kPa (means +/- s.e.m.), respectively. Consistent with the predictions of the cantilever model, setae became significantly stiffer when compressed against the natural path of drag: E(eff) during -45 degrees compression was 110+/-4.7 kPa. Unlike synthetic PSAs, setal arrays act as Hookean elastic solids; setal arrays function as a bed of springs with a directional stiffness, assisting alignment of the adhesive spatular tips with the contact surface during shear loading.

  18. Subdigital setae of narrow-toed geckos, including a Eublepharid (Aeluroscalabotes felinus).

    Science.gov (United States)

    Peattie, Anne M

    2008-07-01

    Subdigital adhesive setae have previously been documented in all legged gecko families except the Eublepharidae. I present evidence that members of Aeluroscalabotes felinus, the only arboreal eublepharids, possess subdigital setae up to 9 mum in length. This discovery suggests that the conditions leading to adhesive setae were probably present in the ancestors of all geckos, rather than arising multiple times within Gekkota. The digits and setae of Aeluroscalabotes resemble those of other climbing, bent-toed geckos. I describe the setal morphology of the following bent-toed species: Cyrtodactylus peguensis, Gonatodes albogularis, and Pristurus rupestris. The presence of subdigital setae is highly correlated with an arboreal lifestyle across geckos and other lizards such as anoles and skinks. Although relatively simple in form, these setae likely confer additional traction that significantly benefits climbing species. Further developmental and biomechanical studies comparing these species with more agile climbers like the Tokay will improve our understanding of the evolutionary processes leading to adhesive setae, and consequently inform engineers attempting to fabricate effective artificial gecko setae. (c) 2008 Wiley-Liss, Inc.

  19. The gecko visual pigment: the chromophore dark exchange reaction.

    Science.gov (United States)

    Crescitelli, F

    1988-02-01

    This study confirms the occurrence of a dark-exchange reaction in the extracted 521-pigment of the Tokay gecko (G. gekko). The present study involved the exchange, in the dark, of the natural 11-cis-chromophore by the 9-cis-10-F-retinal analog. This analog is able to combine with the 521-opsin to regenerate a photopigment at 492 nm. In addition to this shift in absorbance from 521 to 492 nm, the analog photopigment has a photosensitivity some 2.4% that of the native 521-system in the chloride-sufficient state. These two properties of the regenerated analog pigment have simplified the demonstration of a dark exchange of chromophores. At 15 degrees C the 9-cis-10-F-analog replaces the 11-cis-chromophore by at least 30% (density-wise) in about 15 hr. This exchange occurs with the system in the chloride-deficient state. The presence of chloride during the period in the dark significantly reduces the magnitude of the exchange. Apparently, the protein has a more open structure at the chromophoric binding site, allowing this interchange of chromophores. The addition of chloride induces a conformational change at this site, 'burying' the Schiff base and reducing the exchange reaction. The biological implication of this mobile property of the gecko opsin is that it is similar to the behavior of the cone pigment iodopsin but is unlike that of rhodopsins. This supports the idea that the gecko visual cells, despite their appearance as rods, are phylogenetically related to ancestral photopic receptors.

  20. Tokay gecko photoreceptors achieve rod-like physiology with cone-like proteins.

    Science.gov (United States)

    Zhang, Xue; Wensel, Theodore G; Yuan, Ching

    2006-01-01

    The retinal photoreceptors of the nocturnal Tokay gecko (Gekko gekko) consist exclusively of rods by the criteria of morphology and key features of their light responses. Unlike cones, they display robust photoresponses and have relatively slow recovery times. Nonetheless, the major and minor visual pigments identified in gecko rods are of the cone type by sequence and spectroscopic behavior. In the ongoing search for the molecular bases for the physiological differences between cones and rods, we have characterized the molecular biology and biochemistry of the gecko rod phototransduction cascade. We have cloned cDNAs encoding all or part of major protein components of the phototransduction cascade by RT-PCR with degenerate oligonucleotides designed to amplify cone- or rod-like sequences. For all proteins examined we obtained only cone-like and never rod-like sequences. The proteins identified include transducin alpha (Galphat), phosphodiesterase (PDE6) catalytic and inhibitory subunits, cyclic nucleotide-gated channel (CNGalpha) and arrestin. We also cloned cDNA encoding gecko RGS9-1 (Regulator of G Protein Signaling 9, splice variant 1), which is expressed in both rods and cones of all species studied but is typically found at 10-fold higher concentrations in cones, and found that gecko rods contain slightly lower RGS9-1 levels than mammalian rods. Furthermore, we found that the levels of GTPase accelerating protein (GAP) activity and cyclic GMP (cGMP) phosphodiesterase activity were similar in gecko and mammalian rods. These results place substantial constraints on the critical changes needed to convert a cone into a rod in the course of evolution: The many features of phototransduction molecules conserved between those expressed in gecko rods and those expressed in cones cannot explain the physiological differences, whereas the higher levels of RGS9-1 and GAP activity in cones are likely among the essential requirements for the rapid photoresponses of cones.

  1. Modelling of gecko foot for future robot application

    Science.gov (United States)

    Kamaruddin, A.; Ong, N. R.; Aziz, M. H. A.; Alcain, J. B.; Haimi, W. M. W. N.; Sauli, Z.

    2017-09-01

    Every gecko has an approximately million microscale hairs called setae which made it easy for them to cling from different surfaces at any orientation with the aid of Van der Waals force as the primary mechanism used to adhere to any contact surfaces. In this paper, a strain simulation using Comsol Multiphysic Software was conducted on a 3D MEMS model of an actuated gecko foot with the aim of achieving optimal sticking with various polymetric materials for future robots application. Based on the stress and strain analyses done on the seven different polymers, it was found that polysilicon had the best result which was nearest to 0%, indicating the strongest elasticity among the others. PDMS on the hand, failed in the simulation due to its bulk-like nature. Thus, PDMS was not suitable to be used for further study on gecko foot robot.

  2. Industrial Electrostatic-Gecko Gripper, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Perception Robotics is developing an innovative product, the Electrostatic Gecko Gripper? (ESG Gripper), for the industrial automation market. This unique gripping...

  3. Industrial Electrostatic-Gecko Gripper, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Perception Robotics is developing an innovative product, the "Electrostatic Gecko Gripper" (ESG Gripper), for the industrial automation market. This unique gripping...

  4. Genetic diversity of the red-spotted tokay gecko (Gekko gecko Linnaeus, 1758 (Squamata: Gekkonidae in Southeast Asia determined with multilocus enzyme electrophoresis

    Directory of Open Access Journals (Sweden)

    Watee Kongbuntad

    2016-03-01

    Full Text Available Red-spotted tokay geckos, Gekko gecko, are distributed mainly in Southeast Asia. They are a traditional Chinese medicine, with the massive hunting for exports dramatically decreasing their numbers. Information on the genetic diversity of these geckos in Southeast Asia is very limited. This study aims to explore intrapopulation and interpopulation genetic variation and the genetic structure of 16 populations collected from different localities in Thailand, Lao People's Democratic Republic, and Cambodia using multilocus enzyme electrophoresis. Relatively high genetic diversity occurred at both the intrapopulation and interpopulation levels. Genetic differentiation with FST values ranging between 0.006–0.892 was found. Five distinct genetic groups of the red-spotted tokay populations could be classified. A group of populations from northern Thailand showed the highest genetic differentiation from the other groups. Moreover, there was a substantial genetic subdivision depending on the genetic groups with FCT=0.664 and FSC=0.185. This genetic structure is related to geographical distribution and distance between populations, R2=0.5614, p<0.001. Our findings of pronounced genetic structuring and the concomitant conservation genetic consequences if further population loss occurs mean that management actions should therefore focus on the conservation of all of the main sites where tokay geckos still occur.

  5. Changes in materials properties explain the effects of humidity on gecko adhesion.

    Science.gov (United States)

    Puthoff, Jonathan B; Prowse, Michael S; Wilkinson, Matt; Autumn, Kellar

    2010-11-01

    Geckos owe their remarkable stickiness to millions of dry setae on their toes, and the mechanism of adhesion in gecko setae has been the topic of scientific scrutiny for over two centuries. Previously, we demonstrated that van der Waals forces are sufficient for strong adhesion and friction in gecko setae, and that water-based capillary adhesion is not required. However, recent studies demonstrated that adhesion increases with relative humidity (RH) and proposed that surface hydration and capillary water bridge formation is important or even necessary. In this study, we confirmed a significant effect of RH on gecko adhesion, but rejected the capillary adhesion hypothesis. While contact forces of isolated tokay gecko setal arrays increased with humidity, the increase was similar on hydrophobic and hydrophilic surfaces, inconsistent with a capillary mechanism. Contact forces increased with RH even at high shear rates, where capillary bridge formation is too slow to affect adhesion. How then can a humidity-related increase in adhesion and friction be explained? The effect of RH on the mechanical properties of setal β-keratin has escaped consideration until now. We discovered that an increase in RH softens setae and increases viscoelastic damping, which increases adhesion. Changes in setal materials properties, not capillary forces, fully explain humidity-enhanced adhesion, and van der Waals forces remain the only empirically supported mechanism of adhesion in geckos.

  6. Clinical and pathological observations on natural infections of cryptosporidiosis and flagellate protozoa in leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Taylor, M A; Geach, M R; Cooley, W A

    1999-12-11

    A group of adult leopard geckos (Eublepharis macularius) which had been losing weight for several months were found to be infected with Cryptosporidium species. Histological and electron microscopical investigations on the intestines of five of the lizards revealed the presence of large numbers of the developmental stages of Cryptosporidium species attached to the mucosal surface of the lower intestine, and large numbers of flagellate protozoa, suspected to be predominantly Trichomonas species, in the gut lumen. The clinical signs were attributed to the presence of one or both types of parasites.

  7. Effects of metal coatings on adhesive characteristics of Gecko-like microstructures

    International Nuclear Information System (INIS)

    Kim Kyu Hye; An, Tea Chang; Hwang, Hui Yun

    2015-01-01

    Recently, there have been several studies on the inspiration and application of optimized natural structures. One study introduced a new adhesion method that was inspired by the feet of geckos because of their superior features such as high adhesion strength, ease-of-removal, and they are environmentally friendly. Various micro- or nano-structures were fabricated and tested for gecko-like dry adhesives, but gecko-like dry adhesives that were developed became easily worn from frequent use. In this study, we propose a metal-coating method to improve the durability of gecko-like dry adhesives. We evaluate the initial adhesion strength and durability by performing repeated adhesion tests on a glass plate. The initial adhesive strength of gold-coated micro-structures was 60% of that for non-coated ones. However, the adhesive strength of gold-coated micro-structures was kept as 58% of their initial adhesion strength, while that of non-coated ones was only 40%

  8. Effects of metal coatings on adhesive characteristics of Gecko-like microstructures

    Energy Technology Data Exchange (ETDEWEB)

    Kim Kyu Hye; An, Tea Chang; Hwang, Hui Yun [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of)

    2015-11-15

    Recently, there have been several studies on the inspiration and application of optimized natural structures. One study introduced a new adhesion method that was inspired by the feet of geckos because of their superior features such as high adhesion strength, ease-of-removal, and they are environmentally friendly. Various micro- or nano-structures were fabricated and tested for gecko-like dry adhesives, but gecko-like dry adhesives that were developed became easily worn from frequent use. In this study, we propose a metal-coating method to improve the durability of gecko-like dry adhesives. We evaluate the initial adhesion strength and durability by performing repeated adhesion tests on a glass plate. The initial adhesive strength of gold-coated micro-structures was 60% of that for non-coated ones. However, the adhesive strength of gold-coated micro-structures was kept as 58% of their initial adhesion strength, while that of non-coated ones was only 40%.

  9. Ultrasonographic anatomy of reproductive female leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Cojean, Ophélie; Vergneau-Grosset, Claire; Masseau, Isabelle

    2018-02-19

    Captive leopard geckos (Eublepharis macularius) often present to the exotic clinic for gastrointestinal impactions, follicular stasis, or dystocia. To our knowledge, normal ultrasonographic anatomy of these lizards has not been described. The objectives of this prospective, anatomic, analytical study were to develop ultrasound techniques for this species and to describe the normal sonographic anatomy of the head, coelomic cavity, and tail. Eleven, healthy, female leopard geckos were included. A linear array 13-18 MHz transducer was used. Geckos were sedated and restrained in dorsal recumbency for coelomic structure examination and in ventral recumbency for head and tail examinations. Sagittal and transverse images were acquired and authors recorded qualitative and quantitative ultrasonographic characteristics of anatomic structures. The ventral surface of the lungs, liver, gallbladder, caudal vena cava, portal vein, ventral abdominal vein, aorta, ovarian follicles, fat bodies, tail, and brain were visualized in 10 of 11 individuals. In one individual, molt precluded ultrasonographic examination. The heart, kidneys, urinary bladder, spleen, and pancreas were not visualized. The digestive tract was observed in 10 individuals but was too small to be measured. Findings from the current study could be used as a reference for future studies of leopard geckos. © 2018 American College of Veterinary Radiology.

  10. Representation of acoustic signals in the eighth nerve of the Tokay gecko: I. Pure tones.

    Science.gov (United States)

    Sams-Dodd, F; Capranica, R R

    1994-06-01

    A systematic study of the encoding properties of 146 auditory nerve fibers in the Tokay gecko (Gekko gecko, L) was conducted with respect to pure tones and two-tone rate suppression. Our aim was a comprehensive understanding of the peripheral encoding of simple tonal stimuli and their representation by temporal synchronization and spike rate codes as a prelude to subsequent studies of more complex signals. Auditory nerve fibers in the Tokay gecko have asymmetrical, V-shaped excitatory tuning curves with best excitatory frequencies that range from 200-5100 Hz and thresholds between 4-35 dB SPL. A low-frequency excitatory 'tail' extends far into the low-frequency range and two-tone suppression is present only on the high frequency side of the tuning curve. The response properties to pure tones at different loci within a tuning curve can differ greatly, due to evident interactions between the representations of temporal, spectral and intensity stimulus features. For frequencies below 1250 Hz, pure tones are encoded by both temporal synchronization and spike rate codes, whereas above this frequency a fiber's ability to encode the waveform periodicity is lost and only a rate code predominates. These complimentary representations within a tuning curve raise fundamental issues which need to be addressed in interpreting how more complex, bioacoustic communication signals are represented in the peripheral and central auditory system. And since auditory nerve fibers in the Tokay gecko exhibit tonal sensitivity, selective frequency tuning, and iso-intensity and iso-frequency contours that seem comparable to similar measures in birds and mammals, these issues likely apply to most higher vertebrates in general. The simpler wiring diagram of the reptilian auditory system, coupled with the Tokay gecko's remarkable vocalizations, make this animal a good evolutionary model in which to experimentally explore the encoding of more complex sounds of communicative significance.

  11. Gecko proteins induce the apoptosis of bladder cancer 5637 cells by inhibiting Akt and activating the intrinsic caspase cascade.

    Science.gov (United States)

    Kim, Geun-Young; Park, Soon Yong; Jo, Ara; Kim, Mira; Leem, Sun-Hee; Jun, Woo-Jin; Shim, Sang In; Lee, Sang Chul; Chung, Jin Woong

    2015-09-01

    Gecko proteins have long been used as anti-tumor agents in oriental medicine, without any scientific background. Although anti-tumor effects of Gecko proteins on several cancers were recently reported, their effect on bladder cancer has not been investigated. Thus, we explored the anti-tumor effect of Gecko proteins and its cellular mechanisms in human bladder cancer 5637 cells. Gecko proteins significantly reduced the viability of 5637 cells without any cytotoxic effect on normal cells. These proteins increased the Annexin-V staining and the amount of condensed chromatin, demonstrating that the Gecko proteinsinduced cell death was caused by apoptosis. Gecko proteins suppressed Akt activation, and the overexpression of constitutively active form of myristoylated Akt prevented Gecko proteins-induced death of 5637 cells. Furthermore, Gecko proteins activated caspase 9 and caspase 3/7. Taken together, our data demonstrated that Gecko proteins suppressed the Akt pathway and activated the intrinsic caspase pathway, leading to the apoptosis of bladder cancer cells. [BMB Reports 2015; 48(9): 531-536].

  12. Genetic variation and differentiation of Gekko gecko from different populations based on mitochondrial cytochrome b gene sequences and karyotypes.

    Science.gov (United States)

    Qin, Xin-Min; Li, Hui-Min; Zeng, Zhen-Hua; Zeng, De-Long; Guan, Qing-Xin

    2012-06-01

    Black-spotted and red-spotted tokay geckos are distributed in different regions and have significant differences in morphological appearance, but have been regarded as the same species, Gekko gecko, in taxonomy. To determine whether black-spotted and red-spotted tokay geckos are genetically differentiated, we sequenced the entire mitochondrial cytochrome b gene (1147 bp) from 110 individuals of Gekko gecko collected in 11 areas including Guangxi China, Yunnan China, Vietnam, and Laos. In addition, we performed karyotypic analyses of black-spotted tokay geckos from Guangxi China and red-spotted tokay geckos from Laos. These phylogenetic analyses showed that black-spotted and red-spotted tokay geckos are divided into two branches in molecular phylogenetic trees. The average genetic distances are as follows: 0.12-0.47% among six haplotypes in the black-spotted tokay gecko group, 0.12-1.66% among five haplotypes in the red-spotted tokay gecko group, and 8.76-9.18% between the black-spotted and red-spotted tokay geckos, respectively. The karyotypic analyses showed that the karyotype formula is 2n = 38 = 8m + 2sm + 2st + 26t in red-spotted tokay geckos from Laos compared with 2n = 38 = 8m + 2sm + 28t in black-spotted tokay geckos from Guangxi China. The differences in these two kinds of karyotypes were detected on the 15th chromosome. The clear differences in genetic levels between black-spotted and red-spotted tokay geckos suggest a significant level of genetic differentiation between the two.

  13. Comparative studies on the structure and adhesion of setae in G. gecko and G. swinhonis

    Institute of Scientific and Technical Information of China (English)

    GUO; Ce; WANG; WenBo; YU; Min; DAI; ZhenDong

    2007-01-01

    Scanning electron microscopy (SEM) and histological techniques were used to observe and study the setae structures of two gecko species (G. gecko and G. swinhonis) and the relationships between these structures and the adhesive forces. The SEM results showed that the setae of these two species were densely distributed in an orderly fashion, and branched with curved tips. The setae of G. gecko had cluster structures, each cluster containing 4-6 setae whose terminal branches curved towards the center of the toes at ~ 10(°-), the tips of the branches like spatulae and densely arrayed at an interval of less than 0.2-0.3 μm. On the contrary, the branch tips in the setae of G. swinhonis were curled, and the terminal parts of setae curved towards the center of the toes at various angles. Usually the setae of these gecko species branch twice at the top at intervals greater than that of G. gecko. The histological observation found that inside the setae of these two species there were plenty of unevenly distributed contents, such as epithelia, fat cells, pigmental cells and muscle tissue, but no gland cells existed. The results of functional experiments suggested that modifying the structure of gecko's setae could reduce its adhesive ability dramatically, demonstrating the positive correlation between the structure of the gecko's setae and its adhesive ability. The above results provide important information in designing bio-mimic setae and bio-gecko robots.

  14. Binaural processing by the gecko auditory periphery.

    Science.gov (United States)

    Christensen-Dalsgaard, Jakob; Tang, Yezhong; Carr, Catherine E

    2011-05-01

    Lizards have highly directional ears, owing to strong acoustical coupling of the eardrums and almost perfect sound transmission from the contralateral ear. To investigate the neural processing of this remarkable tympanic directionality, we combined biophysical measurements of eardrum motion in the Tokay gecko with neurophysiological recordings from the auditory nerve. Laser vibrometry shows that their ear is a two-input system with approximately unity interaural transmission gain at the peak frequency (∼ 1.6 kHz). Median interaural delays are 260 μs, almost three times larger than predicted from gecko head size, suggesting interaural transmission may be boosted by resonances in the large, open mouth cavity (Vossen et al. 2010). Auditory nerve recordings are sensitive to both interaural time differences (ITD) and interaural level differences (ILD), reflecting the acoustical interactions of direct and indirect sound components at the eardrum. Best ITD and click delays match interaural transmission delays, with a range of 200-500 μs. Inserting a mold in the mouth cavity blocks ITD and ILD sensitivity. Thus the neural response accurately reflects tympanic directionality, and most neurons in the auditory pathway should be directional.

  15. Adhesive interactions of geckos with wet and dry fluoropolymer substrates.

    Science.gov (United States)

    Stark, Alyssa Y; Dryden, Daniel M; Olderman, Jeffrey; Peterson, Kelly A; Niewiarowski, Peter H; French, Roger H; Dhinojwala, Ali

    2015-07-06

    Fluorinated substrates like Teflon® (poly(tetrafluoroethylene); PTFE) are well known for their role in creating non-stick surfaces. We showed previously that even geckos, which can stick to most surfaces under a wide variety of conditions, slip on PTFE. Surprisingly, however, geckos can stick reasonably well to PTFE if it is wet. In an effort to explain this effect, we have turned our attention to the role of substrate surface energy and roughness when shear adhesion occurs in media other than air. In this study, we removed the roughness component inherent to commercially available PTFE and tested geckos on relatively smooth wet and dry fluoropolymer substrates. We found that roughness had very little effect on shear adhesion in air or in water and that the level of fluorination was most important for shear adhesion, particularly in air. Surface energy calculations of the two fluorinated substrates and one control substrate using the Tabor-Winterton approximation and the Young-Dupré equation were used to determine the interfacial energy of the substrates. Using these interfacial energies we estimated the ratio of wet and dry normal adhesion for geckos clinging to the three substrates. Consistent with the results for rough PTFE, our predictions show a qualitative trend in shear adhesion based on fluorination, and the quantitative experimental differences highlight the unusually low shear adhesion of geckos on dry smooth fluorinated substrates, which is not captured by surface energy calculations. Our work has implications for bioinspired design of synthetics that can preferentially stick in water but not in air.

  16. Passive Cushiony Biomechanics of Head Protection in Falling Geckos

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2018-01-01

    Full Text Available Gekko geckos are capable to crawl on the steep even on upside-down surfaces. Such movement, especially at great altitude, puts them at high risks of incidentally dropping down and inevitable body or head impactions, though they may trigger air-righting reaction (ARR to attenuate the landing shocks. However, the air-righting ability (ARA in Gekko geckos is not fully developed. The implementation of ARR in some geckos is quite slow; and for those without tails, the ARR is even unobservable. Since ARA is compromised in Gekko geckos, there must be some other mechanisms responsible for protecting them from head injuries during falls. In this study, we looked into a Gekko gecko’s brain to study its internal environment and structure, using the magnetic resonance imaging (MRI technique. The results showed that the brain parenchyma was fully surrounded by the cerebrospinal fluid (CSF in the skull. A succulent characteristic was presented, which meant the intracalvarium was significantly occupied by the CSF, up to 45% in volume. Then a simplified three-dimensional finite element model was built, and a dynamic simulation was conducted to evaluate the mechanical property of this succulent characteristic during the head impactions. These implied the succulent characteristic may play certain roles on the self-protection in case of head impaction, which is adaptable to the Gekko gecko’s locomotion and behavior.

  17. Molecular phylogeny of Hemidactylus geckos (Squamata: Gekkonidae) of the Indian subcontinent reveals a unique Indian radiation and an Indian origin of Asian house geckos.

    Science.gov (United States)

    Bansal, Rohini; Karanth, K Praveen

    2010-10-01

    Represented by approximately 85 species, Hemidactylus is one of the most diverse and widely distributed genera of reptiles in the world. In the Indian subcontinent, this genus is represented by 28 species out of which at least 13 are endemic to this region. Here, we report the phylogeny of the Indian Hemidactylus geckos based on mitochondrial and nuclear DNA markers sequenced from multiple individuals of widely distributed as well as endemic congeners of India. Results indicate that a majority of the species distributed in India form a distinct clade whose members are largely confined to the Indian subcontinent thus representing a unique Indian radiation. The remaining Hemidactylus geckos of India belong to two other geographical clades representing the Southeast Asian and West-Asian arid zone species. Additionally, the three widely distributed, commensal species (H. brookii, H. frenatus and H. flaviviridis) are nested within the Indian radiation suggesting their Indian origin. Dispersal-vicariance analysis also supports their Indian origin and subsequent dispersal out-of-India into West-Asian arid zone and Southeast Asia. Thus, Indian subcontinent has served as an important arena for diversification amongst the Hemidactylus geckos and in the evolution and spread of its commensal geckos. Copyright 2010 Elsevier Inc. All rights reserved.

  18. Cryptosporidium varanii infection in leopard geckos (Eublepharis macularius) in Argentina

    OpenAIRE

    A. Dellarupe; J.M. Unzaga; G. Moré; M. Kienast; A. Larsen; C. Stiebel; M. Rambeaud; M.C. Venturini

    2016-01-01

    Cryptosporidiosis is observed in reptiles with high morbidity and considerable mortality. The objective of this study was to achieve the molecular identification of Cryptosporidium spp. in pet leopard geckos (Eublepharis macularius) from a breeder colony in Buenos Aires, Argentina. Oocysts comparable to those of Cryptosporidium spp. were detected in three geckos with a history of diarrhea, anorexia and cachexia. Molecular identification methods confirmed the presence of Cryptosporidium varani...

  19. A Review of Sex Determining Mechanisms in Geckos (Gekkota: Squamata)

    OpenAIRE

    Gamble, T.

    2010-01-01

    Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanism...

  20. A Study of lymphangiogenesis in a gecko model of tail autotomy

    International Nuclear Information System (INIS)

    Tsopelas, C.; Munns, S.L.; Lewis, B.; Daniels, C.B.; Cooter, R.D.; Chatterton, B.E.

    2002-01-01

    Full text: Lymphoedema is a debilitating problem for which there is no effective cure. Lymphatic vessels do not regenerate after injuries such as infection, trauma, radiotherapy or tumour invasion. One approach is to determine whether lymph vessels can be regenerated in tissues where these structures have been damaged or removed. This study examined lymphangiogenesis in a gecko model of tail autotomy. Christinus marmoratus can regenerate its tail which is non-oedematous. The lymphatics of gecko tails were visualised using 99m Tc-Sb 2 S 3 colloid, image analyses provided lymph speed and % activity migrated from the injection site. Histological images yielded density and diameter of lymphatic vessels. Measurements were obtained for geckos with non-regenerate tails, 3,6, 9,12, 15, 18 and >24 week (fully) old regenerated tails post autotomy (pa). Fully regenerated tails had significantly slower lymph speed, slower radiocolloid migration from injection site, lower lymphatic density and higher diameter of lymphatic vessels, than similar sized geckos with non-regenerate tails. Their comparison to 6-18 week old tails, confirmed no significant difference in lymph speed, radiocolloid migration or diameter of lymphatic vessels. No measurable lymphatic flow was seen at 3 weeks pa. A functional lymphatic network was established in regenerating gecko tails, where a combination of data elude to a critical lymphangiogenesis period during 3-6 weeks post autotomy. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  1. Advanced gecko-foot-mimetic dry adhesives based on carbon nanotubes.

    Science.gov (United States)

    Hu, Shihao; Xia, Zhenhai; Dai, Liming

    2013-01-21

    Geckos can run freely on vertical walls and even ceilings. Recent studies have discovered that gecko's extraordinary climbing ability comes from a remarkable design of nature with nanoscale beta-keratin elastic hairs on their feet and toes, which collectively generate sufficiently strong van der Waals force to hold the animal onto an opposing surface while at the same time disengaging at will. Vertically aligned carbon nanotube (VA-CNT) arrays, resembling gecko's adhesive foot hairs with additional superior mechanical, chemical and electrical properties, have been demonstrated to be a promising candidate for advanced fibrillar dry adhesives. The VA-CNT arrays with tailor-made hierarchical structures can be patterned and/or transferred onto various flexible substrates, including responsive polymers. This, together with recent advances in nanofabrication techniques, could offer 'smart' dry adhesives for various potential applications, even where traditional adhesives cannot be used. A detailed understanding of the underlying mechanisms governing the material properties and adhesion performances is critical to the design and fabrication of gecko inspired CNT dry adhesives of practical significance. In this feature article, we present an overview of recent progress in both fundamental and applied frontiers for the development of CNT-based adhesives by summarizing important studies in this exciting field, including our own work.

  2. Advanced gecko-foot-mimetic dry adhesives based on carbon nanotubes

    Science.gov (United States)

    Hu, Shihao; Xia, Zhenhai; Dai, Liming

    2012-12-01

    Geckos can run freely on vertical walls and even ceilings. Recent studies have discovered that gecko's extraordinary climbing ability comes from a remarkable design of nature with nanoscale beta-keratin elastic hairs on their feet and toes, which collectively generate sufficiently strong van der Waals force to hold the animal onto an opposing surface while at the same time disengaging at will. Vertically aligned carbon nanotube (VA-CNT) arrays, resembling gecko's adhesive foot hairs with additional superior mechanical, chemical and electrical properties, have been demonstrated to be a promising candidate for advanced fibrillar dry adhesives. The VA-CNT arrays with tailor-made hierarchical structures can be patterned and/or transferred onto various flexible substrates, including responsive polymers. This, together with recent advances in nanofabrication techniques, could offer `smart' dry adhesives for various potential applications, even where traditional adhesives cannot be used. A detailed understanding of the underlying mechanisms governing the material properties and adhesion performances is critical to the design and fabrication of gecko inspired CNT dry adhesives of practical significance. In this feature article, we present an overview of recent progress in both fundamental and applied frontiers for the development of CNT-based adhesives by summarizing important studies in this exciting field, including our own work.

  3. Prevalence of cryptosporidium infection and characteristics of oocyst shedding in a breeding colony of leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Deming, Clare; Greiner, Ellis; Uhl, Elizabeth W

    2008-12-01

    Cryptosporidiosis is an emerging problem in reptile medicine and has been associated with a wasting syndrome in leopard geckos (Eublepharis macularius). This study determined the prevalence of infection in a breeding colony of leopard geckos to be 9.8%. Two groups of 20 geckos, one that was fecal positive for oocysts of Cryptosporidium sp., and one, whose individuals were fecal negative at the inception of the study, were followed for 2 mo. Fecal samples were tested for oocysts every 2 wk, body weights were measured, and a body condition score was assigned for each gecko. Selected geckos from these two groups were euthanized and necropsied. There were statistically significant differences (P weight, mean body condition score, and prevalence of infection. Cryptosporidium sp. infection is endemic in this breeding colony, and there were a large number of geckos with a subclinical or carrier state of infection. These animals continued to be infected with Cryptosporidium sp. but gained weight and remained in good body condition. Only one gecko in the entire group of 40 was confirmed to be negative for oocysts or developmental stages by repeated fecal exams and histopathology. An additional 37 severely emaciated geckos from the breeding colony were euthanized, and all were positive for Cryptosporidium sp. on histopathologic examination of the gastrointestinal tract. The results of this study indicate that although some animals can recover from a clinical infection, if a gecko is severely wasted, it should be euthanized because of the poor prognosis and possible source of infection to other geckos.

  4. Self-Cleaning Synthetic Adhesive Surfaces Mimicking Tokay Geckos.

    Energy Technology Data Exchange (ETDEWEB)

    Branson, Eric D.; Singh, Seema; Burckel, David Bruce; Fan, Hongyou; Houston, Jack E.; Brinker, C. Jeffrey; Johnson, Patrick

    2006-11-01

    A gecko's extraordinary ability to suspend itself from walls and ceilings of varied surface roughness has interested humans for hundreds of years. Many theories and possible explanations describing this phenomenon have been proposed including sticky secretions, microsuckers, and electrostatic forces; however, today it is widely accepted that van der Waals forces play the most important role in this type of dry adhesion. Inarguably, the vital feature that allows a gecko's suspension is the presence of billions 3 of tiny hairs on the pad of its foot called spatula. These features are small enough to reach within van der Waals distances of any surface (spatula radius %7E100 nm); thus, the combined effect of billions of van der Waals interactions is more than sufficient to hold a gecko's weight to surfaces such as smooth ceilings or wet glass. Two lithographic approaches were used to make hierarchal structures with dimensions similar to the gecko foot dimensions noted above. One approach combined photo-lithography with soft lithography (micro-molding). In this fabrication scheme the fiber feature size, defined by the alumina micromold was 0.2 um in diameter and 60 um in height. The second approach followed more conventional photolithography-based patterning. Patterned features with dimensions %7E0.3 mm in diameter by 0.5 mm tall were produced. We used interfacial force microscopy employing a parabolic diamond tip with a diameter of 200 nm to measure the surface adhesion of these structures. The measured adhesive forces ranged from 0.3 uN - 0.6 uN, yielding an average bonding stress between 50 N/cm2 to 100 N/cm2. By comparison the reported literature value for the average stress of a Tokay gecko foot is 10 N/cm2. Acknowledgements This work was funded by Sandia National Laboratory's Laboratory Directed Research & Development program (LDRD). All coating processes were conducted in the cleanroom facility located at the University of New Mexico

  5. The impact of parasites during range expansion of an invasive gecko.

    Science.gov (United States)

    Barnett, Louise K; Phillips, Ben L; Heath, Allen C G; Coates, Andrew; Hoskin, Conrad J

    2018-02-14

    Host-parasite dynamics can play a fundamental role in both the establishment success of invasive species and their impact on native wildlife. The net impact of parasites depends on their capacity to switch effectively between native and invasive hosts. Here we explore host-switching, spatial patterns and simple fitness measures in a slow-expanding invasion: the invasion of Asian house geckos (Hemidactylus frenatus) from urban areas into bushland in Northeast Australia. In bushland close to urban edges, H. frenatus co-occurs with, and at many sites now greatly out-numbers, native geckos. We measured prevalence and intensity of Geckobia mites (introduced with H. frenatus), and Waddycephalus (a native pentastome). We recorded a new invasive mite species, and several new host associations for native mites and geckos, but we found no evidence of mite transmission between native and invasive geckos. In contrast, native Waddycephalus nymphs were commonly present in H. frenatus, demonstrating this parasite's capacity to utilize H. frenatus as a novel host. Prevalence of mites on H. frenatus decreased with distance from the urban edge, suggesting parasite release towards the invasion front; however, we found no evidence that mites affect H. frenatus body condition or lifespan. Waddycephalus was present at low prevalence in bushland sites and, although its presence did not affect host body condition, our data suggest that it may reduce host survival. The high relative density of H. frenatus at our sites, and their capacity to harbour Waddycephalus, suggests that there may be impacts on native geckos and snakes through parasite spillback.

  6. Coupled effects of the temperature and the relative humidity on gecko adhesion

    International Nuclear Information System (INIS)

    Peng, Zhilong; Yang, Yazheng; Chen, Shaohua

    2017-01-01

    To explain the inconsistent results of experiments on temperature-dependent gecko adhesion, a theoretical peeling model is established wherein a nano-thin film is adopted to simulate a gecko spatula. The model considers not only the respective effects of temperature and environmental humidity on the peel-off force but also the coupled effect of both factors. Increasing temperature is found to lead to a decreasing peel-off force if the environmental humidity is uncontrolled. However, if the environmental humidity is constant, the peel-off force is insensitive to the temperature and remains almost constant. The synthetic theoretical analysis demonstrates that the seemingly contradictory results of temperature-dependent gecko adhesion experiments are actually consistent under their respective experimental conditions. This inconsistency is mainly due to the environmental humidity, which varies with the changing temperature if it is not artificially controlled. The results cannot only reasonably explain the different experimental results for the effect of temperature on gecko adhesion but can also facilitate the design of temperature-controlled or humidity-controlled adhesion sensors by tuning the environmental humidity or temperature. (paper)

  7. Effect of 16-Day Spaceflight on the Morphology of Thick-Toed Geckos (Pachydactylus Bibronii Smith, 1846)

    Science.gov (United States)

    Gulimova, V. I.; Nikitin, V. B.; Asadchikov, V. E.; Buzmakov, A. V.; Okshtein, I. L.; Almeida, E. A. C.; Ilyin, E. A.; Tairbekov, M. G.; Saveliev, S. V.

    2006-01-01

    There are grounds to believe that space flown experiments on thick-toed geckos may help solve the problem of floatation of vertebrates in microgravity. Geckos of this species carry on the lower surface of their toes numerous setae, which allow them to remain attached to any surfaces regardless of the gravitational effects. Experiments were performed on 5 animals in each of the following groups: flight, basal, synchronous and laboratory controls. 32 hours after a 16- day flight the animals were euthanazed and examined using traditional histology and X-ray microtomography. Body mass losses were 10% in the flight animals, 7.4% in the synchronous controls, and 12.3% in the laboratory controls. Since the flight and synchronous animals were kept at 15-19 C, whereas the laboratory controls - at 26-28 C, it can be inferred that environmental temperatures impacted animal metabolism no less than flight induced stress. Blood tests of the flown animals showed a 12% decrease of erythrocytes and a 40% decrease of dark-nuclear granulocytes, with the number of light-nuclear granulocytes remaining unchanged. In the small intestine the number of goblet cells increased allowing them to occupy a large portion of the cyptal surface. Enhanced secretion was accompanied by the appearance of dead intestinal cells in the lumen. Clusters of degraded hepatocytes were found at the liver edges of flight animals. Signs of liver involution were similar to the changes produced by alcohol consumption but did not spread to its central part. In the heart, insignificant hypertrophy and excessive blood supply that still remained within the physiological norm were detected. No significant changes were found in the pancreas, lungs, nervous systems or the snouts of the flown animals, but the volume of their gallbladders was greater than in controls. The epithelium of toe pads of the flight animals became thinner. Histological examination of the humerus did not demonstrate significant mineral losses

  8. Nanohairs and nanotubes: Efficient structural elements for gecko-inspired artificial dry adhesives

    KAUST Repository

    Jeong, Hoon Eui

    2009-08-01

    An overview of the recent progress in the development of gecko-inspired synthetic dry adhesives is presented, with particular emphasis on two major structural elements of nanohairs and nanotubes. With the advance of nanofabrication techniques, recently developed dry adhesives made of nanohairs and nanotubes show excellent adhesion strength, smart directional adhesion as well as rough surface adaptability by better mimicking gecko foot hairs. After a brief description of the requirements for high-performance artificial dry adhesives, a variety of synthetic adhesives are described based on materials and structural features of the gecko-inspired nanostructures. In addition, current challenges and future directions towards an optimized synthetic dry adhesive are presented. © 2009 Elsevier Ltd. All rights reserved.

  9. Nanohairs and nanotubes: Efficient structural elements for gecko-inspired artificial dry adhesives

    KAUST Repository

    Jeong, Hoon Eui; Suh, Kahp Y.

    2009-01-01

    An overview of the recent progress in the development of gecko-inspired synthetic dry adhesives is presented, with particular emphasis on two major structural elements of nanohairs and nanotubes. With the advance of nanofabrication techniques, recently developed dry adhesives made of nanohairs and nanotubes show excellent adhesion strength, smart directional adhesion as well as rough surface adaptability by better mimicking gecko foot hairs. After a brief description of the requirements for high-performance artificial dry adhesives, a variety of synthetic adhesives are described based on materials and structural features of the gecko-inspired nanostructures. In addition, current challenges and future directions towards an optimized synthetic dry adhesive are presented. © 2009 Elsevier Ltd. All rights reserved.

  10. Antipredatory reaction of the leopard gecko Eublepharis macularius to snake predators.

    Science.gov (United States)

    Landová, Eva; Musilová, Veronika; Polák, Jakub; Sedláčková, Kristýna; Frynta, Daniel

    2016-10-01

    Ability to recognize a risk of predation and react with adaptive antipredatory behavior can enhance fitness, but has some costs as well. Animals can either specifically react on the most dangerous predators (threat-sensitive avoidance) or they have safe but costly general wariness avoiding all potential predators. The level of threat may depend on the predator's foraging ecology and distribution with the prey with sympatric and specialist species being the most dangerous. We used 2 choice trials to investigate antipredatory behavior of captive born and wild-caught leopard geckos confronted with different snake predators from 2 families (Colubridae, Boidae) varying in foraging ecology and sympatric/allopatric distribution with the geckos. Predator-naïve subadult individuals have general wariness, explore both chemically and visually, and perform antipredatory postures toward a majority of snake predators regardless of their sympatry/allopatry or food specialization. The most exaggerated antipredatory postures in both subadult and adult geckos were toward 2 sympatric snake species, the spotted whip snake Hemorrhois ravergieri , an active forager, and the red sand boa Eryx johnii , a subterranean snake with a sit-and-wait strategy. In contrast, also subterranean but allopatric the Kenyan sand boa Eryx colubrinus did not elicit any antipredatory reaction. We conclude that the leopard gecko possesses an innate general antipredatory reaction to different species of snake predators, while a specific reaction to 2 particular sympatric species can be observed. Moreover, adult wild caught geckos show lower reactivity compared with the captive born ones, presumably due to an experience of a real predation event that can hardly be simulated under laboratory conditions.

  11. Friction and adhesion of gecko-inspired PDMS flaps on rough surfaces.

    Science.gov (United States)

    Yu, Jing; Chary, Sathya; Das, Saurabh; Tamelier, John; Turner, Kimberly L; Israelachvili, Jacob N

    2012-08-07

    Geckos have developed a unique hierarchical structure to maintain climbing ability on surfaces with different roughness, one of the extremely important parameters that affect the friction and adhesion forces between two surfaces. Although much attention has been paid on fabricating various structures that mimic the hierarchical structure of a gecko foot, yet no systematic effort, in experiment or theory, has been made to quantify the effect of surface roughness on the performance of the fabricated structures that mimic the hierarchical structure of geckos. Using a modified surface forces apparatus (SFA), we measured the adhesion and friction forces between microfabricated tilted PDMS flaps and optically smooth SiO(2) and rough SiO(2) surfaces created by plasma etching. Anisotropic adhesion and friction forces were measured when sliding the top glass surface along (+y) and against (-y) the tilted direction of the flaps. Increasing the surface roughness first increased the adhesion and friction forces measured between the flaps and the rough surface due to topological matching of the two surfaces but then led to a rapid decrease in both of these forces. Our results demonstrate that the surface roughness significantly affects the performance of gecko mimetic adhesives and that different surface textures can either increase or decrease the adhesion and friction forces of the fabricated adhesives.

  12. Highly durable and unidirectionally stooped polymeric nanohairs for gecko-like dry adhesive

    International Nuclear Information System (INIS)

    Im, Hyeon Seong; Kwon, Ki Yoon; Kim, Jong Uk; Kim, Tae-il; Kim, Kwang Su; Yi, Hoon; Jeong, Hoon Eui; Yoo, Pil J; Pang, Changhyun

    2015-01-01

    Gecko-like dry adhesive using high aspect ratio polymeric nanohairs has insuperable limitations, although it has huge potential in many applications. Repeated harsh contacts on a target substrate lead to physical collapse of nanohairs and significant degradation of the adhesion property, because the polymeric nanohairs are quite fragile due to poor mechanical robustness. Herein, we demonstrate a highly robust gecko-like dry adhesive with unidirectionally stooped polymeric nanohairs (diameter 100 nm) with a high aspect ratio (∼9) using an ultrathin metal coating. 100 cycles of repeated adhesion tests with 1 N preloading force did not significantly degrade adhesion or cause collapse of nanohairs. We believe that this approach allows gecko-like dry adhesive to be utilized in many related applications and diverse industry interests. (paper)

  13. Systemic therapy and attachment narratives: Attachment Narrative Therapy.

    Science.gov (United States)

    Dallos, Rudi; Vetere, Arlene

    2014-10-01

    This article outlines an integration of attachment theory with narrative theory and systemic theory and practice: Attachment Narrative Therapy (ANT). This integration offers a more powerful explanatory formulation of the development and maintenance of human distress in relationships, families and communities, and gives direction to psychotherapeutic intervention. © The Author(s) 2014.

  14. A third, ultraviolet-sensitive, visual pigment in the Tokay gecko (Gekko gekko).

    Science.gov (United States)

    Loew, E R

    1994-06-01

    Numerous extraction and microspectrophotometric studies have shown that the nocturnal Tokay gecko (Gekko gekko), has two visual pigments: a "green" with lambda max at 521 nm and a "blue" at 467 nm. In addition, similar studies on other nocturnal gecko species have found only the same two classes of visual pigment. With the finding that some diurnal species of gecko have a third visual pigment class with lambda max peaking in the UV, doubts were raised concerning the presence of only two visual pigment classes in nocturnal forms. Therefore, a microspectrophotometric re-examination of the Tokay gecko was undertaken to look specifically for a UV visual pigment. A UV-absorbing pigment (364 nm lambda max) was found in approx. 20% of the thin outer segments of type C double rods, thought previously to contain only the 467 nm pigment. That this UV-absorbing pigment was truly a visual pigment was confirmed by its dichroism, behaviour following exposure to UV radiation and "nomogram" fit. It is suggested that this visual pigment had been seen in previous microspectrophotometric studies, but its similarity to known photoproducts peaking in the same spectral region resulted in a case of mistaken identity.

  15. Where to “Rock”? Choice of retreat sites by a gecko in a semi-arid habitat

    Directory of Open Access Journals (Sweden)

    Andreia Penado

    2015-06-01

    Full Text Available The Selvagens gecko (Tarentola boettgeri bischoffi Joger, 1984 is a medium sized gecko endemic to the Selvagens archipelago, Madeira, Portugal. The biology of this gecko is poorly known and in this study we present the first evidence regarding its habitat use. In 2010 (spring and autumn and 2011 (spring, we collected data on the characteristics of the habitat surrounding 168 rocks used by these geckos as retreat sites, as well as on 75 randomly selected rocks. We also recorded body measurements of the individuals caught under each rock. In both seasons retreat site occupancy was found to be related to rock area, with geckos being found mainly under large rocks. Interestingly, we found that in spring heavier males, in better body condition, occupied the largest rocks and larger geckos occupied rocks closer to creek beds. Our results shed some light upon the behavioural ecology of this nocturnally active ectotherm, that spends the day under a retreat site: i intraspecific competition may be an ecological factor prevalent in this species, since larger individuals occupy larger rocks, located in a presumably high quality micro-habitat; ii the possibility of spring territoriality in males, that compete for good quality shelters.

  16. Detection rates of geckos in visual surveys: Turning confounding variables into useful knowledge

    Science.gov (United States)

    Lardner, Bjorn; Rodda, Gordon H.; Yackel Adams, Amy A.; Savidge, Julie A.; Reed, Robert N.

    2016-01-01

    Transect surveys without some means of estimating detection probabilities generate population size indices prone to bias because survey conditions differ in time and space. Knowing what causes such bias can help guide the collection of relevant survey covariates, correct the survey data, anticipate situations where bias might be unacceptably large, and elucidate the ecology of target species. We used negative binomial regression to evaluate confounding variables for gecko (primarily Hemidactylus frenatus and Lepidodactylus lugubris) counts on 220-m-long transects surveyed at night, primarily for snakes, on 9,475 occasions. Searchers differed in gecko detection rates by up to a factor of six. The worst and best headlamps differed by a factor of at least two. Strong winds had a negative effect potentially as large as those of searchers or headlamps. More geckos were seen during wet weather conditions, but the effect size was small. Compared with a detection nadir during waxing gibbous (nearly full) moons above the horizon, we saw 28% more geckos during waning crescent moons below the horizon. A sine function suggested that we saw 24% more geckos at the end of the wet season than at the end of the dry season. Fluctuations on a longer timescale also were verified. Disturbingly, corrected data exhibited strong short-term fluctuations that covariates apparently failed to capture. Although some biases can be addressed with measured covariates, others will be difficult to eliminate as a significant source of error in longterm monitoring programs.

  17. Role of seta angle and flexibility in the gecko adhesion mechanism

    Science.gov (United States)

    Hu, Congcong; Alex Greaney, P.

    2014-08-01

    A model is developed to describe the reversible nature of gecko dry adhesion. The central aspect of this model is that the seta can be easily peeled away from the contacting surface by a small moment at the contact tip. It is shown that this contact condition is very sensitive, but can result in robust adhesion if individual setae are canted and highly flexible. In analogy to the "cone of friction," we consider the "adhesion region"—the domain of normal and tangential forces that maintain adhesion. Results demonstrate that this adhesion region is highly asymmetric enabling the gecko to adhere under a variety of loading conditions associated with scuttling horizontally, vertically, and inverted. Moreover, under each of these conditions, there is a low energy path to de-adhesion. In this model, obliquely canted seta (as possessed by geckos) rather than vertically aligned fibers (common in synthetic dry adhesive) provides the most robust adhesion.

  18. Mechanical work as a determinant of prey-handling behavior in the tokay gecko (Gekko gecko).

    Science.gov (United States)

    Andrews, C; Bertram, J E

    1997-01-01

    In this study an in vitro analysis of the force and mechanical work required to bite prey items of different size and physical character is combined with an in vivo analysis of prey-handling behavior in the tokay gecko (Gekko gecko). The force required to bite and the work of biting increase with prey size, but the rate of increase is prey specific, with crickets (Acheta domestica) requiring substantially more force and work per bite than larvae (Galleria mellonella and Manduca sexta) for all but the smallest prey. Prey-handling behavior is also prey specific. Geckos exert more bites per feeding event on small crickets than on small insect larvae, but the number of bites increases faster with prey mass for larvae than for crickets. Combination of the in vitro mechanical measurements with the in vivo behavior analysis allows the calculation of total mechanical work per feeding event and indicates that total work increases with prey size but that the difference between prey types is far less than predicted from the differences in structural properties of the prey. This occurs because the number of bites and work per bite relationships tend to cancel the differences in the total work necessary to process each prey type. Thus, when considering the effect of prey size, a 13-fold greater rate of increase in bite force and an 18-fold greater rate of increase of work per bit for crickets over larvae was partially compensated for by a threefold increase in the number of bites used on larvae relative to crickets. These results can be interpreted in two ways. The effect of mechanical work in feeding behavior suggests that the energetics of jaw adductor musculature could play a greater role in governing the feeding behavior of this lizard than has previously been expected. Alternatively, the scaling of work in feeding over a range of prey sizes suggests distinct differences in the geometric features of the prey that determine how they are processed.

  19. Cryptosporidium varanii infection in leopard geckos (Eublepharis macularius) in Argentina.

    Science.gov (United States)

    Dellarupe, A; Unzaga, J M; Moré, G; Kienast, M; Larsen, A; Stiebel, C; Rambeaud, M; Venturini, M C

    2016-01-01

    Cryptosporidiosis is observed in reptiles with high morbidity and considerable mortality. The objective of this study was to achieve the molecular identification of Cryptosporidium spp. in pet leopard geckos (Eublepharis macularius) from a breeder colony in Buenos Aires, Argentina. Oocysts comparable to those of Cryptosporidium spp. were detected in three geckos with a history of diarrhea, anorexia and cachexia. Molecular identification methods confirmed the presence of Cryptosporidium varanii (syn. C. saurophilum). This agent was considered to be the primary cause of the observed clinical disease. This is the first description of C. varanii infection in pet reptiles in Argentina.

  20. Cryptosporidium varanii infection in leopard geckos (Eublepharis macularius in Argentina

    Directory of Open Access Journals (Sweden)

    A. Dellarupe

    2016-06-01

    Full Text Available Cryptosporidiosis is observed in reptiles with high morbidity and considerable mortality. The objective of this study was to achieve the molecular identification of Cryptosporidium spp. in pet leopard geckos (Eublepharis macularius from a breeder colony in Buenos Aires, Argentina. Oocysts comparable to those of Cryptosporidium spp. were detected in three geckos with a history of diarrhea, anorexia and cachexia. Molecular identification methods confirmed the presence of Cryptosporidium varanii (syn. C. saurophilum. This agent was considered to be the primary cause of the observed clinical disease. This is the first description of C. varanii infection in pet reptiles in Argentina.

  1. Cryptosporidium varanii infection in leopard geckos ( Eublepharis ...

    African Journals Online (AJOL)

    Cryptosporidiosis is observed in reptiles with high morbidity and considerable mortality. The objective of this study was to achieve the molecular identification of Cryptosporidium spp. in pet leopard geckos (Eublepharis macularius) from a breeder colony in Buenos Aires, Argentina. Oocysts comparable to those of ...

  2. Multiple origin of diurnality in geckos: evidence from eye lens crystallins

    Science.gov (United States)

    Röll, Beate

    2001-05-01

    The large lizard family Gekkonidae comprises about 90 genera (1000 species). While most geckos are nocturnal, the members of about 15 genera are diurnal. All of these species are 'tertiarily' diurnal, i.e. they are descended from 'secondarily' nocturnal ancestors. They have adapted to a diurnal lifestyle in quite different ways, as can be deduced by the crystallin proteins in their lenses. Evaluation of the heterogeneous lens crystallin compositions of diurnal geckos reveals that there are at least three lineages that regained diurnality independently.

  3. Folklore and traditional ecological knowledge of geckos in Southern Portugal: implications for conservation and science

    Science.gov (United States)

    2011-01-01

    Traditional Ecological Knowledge (TEK) and folklore are repositories of large amounts of information about the natural world. Ideas, perceptions and empirical data held by human communities regarding local species are important sources which enable new scientific discoveries to be made, as well as offering the potential to solve a number of conservation problems. We documented the gecko-related folklore and TEK of the people of southern Portugal, with the particular aim of understanding the main ideas relating to gecko biology and ecology. Our results suggest that local knowledge of gecko ecology and biology is both accurate and relevant. As a result of information provided by local inhabitants, knowledge of the current geographic distribution of Hemidactylus turcicus was expanded, with its presence reported in nine new locations. It was also discovered that locals still have some misconceptions of geckos as poisonous and carriers of dermatological diseases. The presence of these ideas has led the population to a fear of and aversion to geckos, resulting in direct persecution being one of the major conservation problems facing these animals. It is essential, from both a scientific and conservationist perspective, to understand the knowledge and perceptions that people have towards the animals, since, only then, may hitherto unrecognized pertinent information and conservation problems be detected and resolved. PMID:21892925

  4. Molecular evolution of the cone visual pigments in the pure rod-retina of the nocturnal gecko, Gekko gekko.

    Science.gov (United States)

    Yokoyama, S; Blow, N S

    2001-10-03

    We have isolated a full-length cDNA encoding a putative ultraviolet (UV)-sensitive visual pigment of the Tokay gecko (Gekko gekko). This clone has 57 and 59% sequence similarities to the gecko RH2 and MWS pigment genes, respectively, but it shows 87% similarity to the UV pigment gene of the American chameleon (Anolis carolinensis). The evolutionary rates of amino acid replacement are significantly higher in the three gecko pigments than in the corresponding chameleon pigments. The accelerated evolutionary rates reflect not only the transition from cones to rods in the retina but also the blue-shift in the absorption spectra of the gecko pigments.

  5. Repeated origin and loss of adhesive toepads in geckos.

    Directory of Open Access Journals (Sweden)

    Tony Gamble

    Full Text Available Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

  6. Repeated origin and loss of adhesive toepads in geckos.

    Science.gov (United States)

    Gamble, Tony; Greenbaum, Eli; Jackman, Todd R; Russell, Anthony P; Bauer, Aaron M

    2012-01-01

    Geckos are well known for their extraordinary clinging abilities and many species easily scale vertical or even inverted surfaces. This ability is enabled by a complex digital adhesive mechanism (adhesive toepads) that employs van der Waals based adhesion, augmented by frictional forces. Numerous morphological traits and behaviors have evolved to facilitate deployment of the adhesive mechanism, maximize adhesive force and enable release from the substrate. The complex digital morphologies that result allow geckos to interact with their environment in a novel fashion quite differently from most other lizards. Details of toepad morphology suggest multiple gains and losses of the adhesive mechanism, but lack of a comprehensive phylogeny has hindered efforts to determine how frequently adhesive toepads have been gained and lost. Here we present a multigene phylogeny of geckos, including 107 of 118 recognized genera, and determine that adhesive toepads have been gained and lost multiple times, and remarkably, with approximately equal frequency. The most likely hypothesis suggests that adhesive toepads evolved 11 times and were lost nine times. The overall external morphology of the toepad is strikingly similar in many lineages in which it is independently derived, but lineage-specific differences are evident, particularly regarding internal anatomy, with unique morphological patterns defining each independent derivation.

  7. Congenital ankyloblepharon in a leopard gecko (Eublepharis macularius).

    Science.gov (United States)

    Rival, Franck

    2015-01-01

    A 6-month-old leopard gecko with unilateral partially fused eyelids since birth was presented for examination. A diagnosis of congenital ankyloblepharon was made and surgical correction was performed successfully. © 2014 American College of Veterinary Ophthalmologists.

  8. Preliminary In Vivo Experiments on Adhesion of Geckos

    OpenAIRE

    Lepore, E.; Brianza, S.; Antoniolli, F.; Buono, M.; Carpinteri, A.; Pugno, N.

    2008-01-01

    We performed preliminary experiments on the adhesion of a Tokay gecko on surfaces with different roughness, with or without particles with significant different granulometry, before/after or during the moult. The results were analyzed using the Weibull statistics.

  9. Folklore and traditional ecological knowledge of geckos in Southern Portugal: implications for conservation and science

    Directory of Open Access Journals (Sweden)

    Vila-Viçosa Carlos M

    2011-09-01

    Full Text Available Abstract Traditional Ecological Knowledge (TEK and folklore are repositories of large amounts of information about the natural world. Ideas, perceptions and empirical data held by human communities regarding local species are important sources which enable new scientific discoveries to be made, as well as offering the potential to solve a number of conservation problems. We documented the gecko-related folklore and TEK of the people of southern Portugal, with the particular aim of understanding the main ideas relating to gecko biology and ecology. Our results suggest that local knowledge of gecko ecology and biology is both accurate and relevant. As a result of information provided by local inhabitants, knowledge of the current geographic distribution of Hemidactylus turcicus was expanded, with its presence reported in nine new locations. It was also discovered that locals still have some misconceptions of geckos as poisonous and carriers of dermatological diseases. The presence of these ideas has led the population to a fear of and aversion to geckos, resulting in direct persecution being one of the major conservation problems facing these animals. It is essential, from both a scientific and conservationist perspective, to understand the knowledge and perceptions that people have towards the animals, since, only then, may hitherto unrecognized pertinent information and conservation problems be detected and resolved.

  10. Preliminary In Vivo Experiments on Adhesion of Geckos

    Directory of Open Access Journals (Sweden)

    E. Lepore

    2008-01-01

    Full Text Available We performed preliminary experiments on the adhesion of a Tokay gecko on surfaces with different roughness, with or without particles with significant different granulometry, before/after or during the moult. The results were analyzed using the Weibull statistics.

  11. Attachment is a dynamic system

    Directory of Open Access Journals (Sweden)

    Zlatka Cugmas

    2003-04-01

    Full Text Available On the basis of the study of recent scientific literature about the development of attachment, the author answers the following questions: which are the postulates the theory of attachment has about the stability of the patterns of attachment, which level of stability in the patterns of attachment from infancy to adulthood these studies illuminate and which factors significantly influence the (instability of the patterns of attachment in time. The theory of attachment assumes that normal circumstances elicit stability. Changes, however, can be the result of important events influencing the sensitivity of the object of attachment. Agreement has not yet been reached regarding the percentage of stability in the patterns of attachment. There is more agreement regarding attachment in adulthood than that in childhood. The results depend on the size and characteristics of the subjects of the research, the measuring instruments, type of data analysis etc. The author concludes that attachment is a dynamic system influenced by significant changes in life (the cognitive development of the child, external care, parents' divorce, different stressful situations. As the influence of stressful events on the individual person' s quality of attachment is examined, it is necessary to consider also his/her temperamental characteristics, role of other people in their lives, etc.

  12. Identification of the reptilian prolactin and its receptor cDNAs in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Kato, Keisuke; Ikemoto, Tadahiro; Park, Min Kyun

    2005-02-14

    In spite of their physiological significance, there is no available information about the nucleotide sequences of prolactin (PRL) and its receptor in reptilian species. In order to fill this gap, PRL and its receptor cDNAs were identified in a reptilian species, the leopard gecko Eublepharis macularius. The deduced leopard gecko PRL polypeptide showed high identities with the corresponding polypeptides of other reptiles. The leopard gecko PRL receptor (PRLR) was estimated to have tandem repeated regions in its extracellular domain, which had been originally found in avian PRLR. Molecular phylogenetic analysis suggests that these tandem repeated regions were generated by the duplication of the extracellular region in the latest common ancestor among reptiles and birds. In addition, tissue distributions of PRL and PRLR in the leopard gecko were examined by the reverse transcription-polymerase chain reaction (RT-PCR). PRLR mRNA was detected in all tissues examined and highly expressed in the whole brain, pituitary, intestine, kidney, ovary, oviduct and testis. Whereas, PRL mRNA was expressed in the whole brain, pituitary, ovary and testis. The co-expressions of PRL and its receptor in some extrapituitary organs suggest that PRL acts as an autocrine/paracrine factor in such organs of the leopard gecko.

  13. A review of the Namaqua gecko, Pachydactylus namaquensis ...

    African Journals Online (AJOL)

    An analysis of morphological and allozyme variation in the Namaqua gecko, Pachydactylus namaquensis from southern Africa is presented. Three separately evolving lineages, well defined by morphology and allozyme variation, are identified. The isolated southern population, occurring on the southern escarpment and ...

  14. Footprints in the sand: independent reduction of subdigital lamellae in the Namib-Kalahari burrowing geckos.

    Science.gov (United States)

    Lamb, Trip; Bauer, Aaron M

    2006-04-07

    Many desert organisms exhibit convergence, and certain physical factors such as windblown sands have generated remarkably similar ecomorphs across divergent lineages. The burrowing geckos Colopus, Chondrodactylus and Palmatogecko occupy dune ecosystems in the Namib and Kalahari deserts of southwest Africa. Considered closely related, they share several putative synapomorphies, including reduced subdigital pads (toe pads) and spinose digital scales. Though recognized as part of Africa's ecologically diverse Pachydactylus Group, the burrowing geckos' precise phylogenetic affinities remain elusive. Convergent pedal modification provides a tenable alternative explaining the geckos' derived terrestriality and adaptation to Namib and Kalahari sands. We generated a molecular phylogeny for the Pachydactylus Group to examine evolutionary relationships among the burrowing geckos and infer historical patterns of pedal character change. Bayesian and parsimony analyses revealed all three burrowing genera to be deeply nested within Pachydactylus, each genus belonging to a separate clade. Strong support for these distinct clades indicates ecomorphological adaptations for burrowing have evolved independently three times in the southern Pachydactylus Group. We argue that the physical properties of Namib and Kalahari sands played a principal role in selecting for pedal similarity.

  15. Comparative Studies of the Thick-Toed Geckos after the 16 and 12 Days Spaceflight in > Experiments

    Science.gov (United States)

    Nikitin, V. B.; Proshchina, A. E.; Kharlamova, A. S.; Barabanov, V. M.; Krivova, J. S.; Godovalova, O. S.; Savelieva, E. S.; Makarov, A. N.; Gulimova, V. I.; Okshtein, I. L.; Naidenko, S. V.; Souza, K. A.; Almeida, E. A. C.; Ilyin, E. A.; Saveliev, S. V.

    2008-06-01

    In our study we compare the data from analysis of thick-toed geckoes Pachydactylus turneri from 16 and 12 days spaceflights onboard «Foton-M2» (M2) and «Foton-M3» (M3) satellites respectively. These studies were realized in the frames of Russian-American joint experiments. In M2 they were performed on 4 females and 1 male in each of the following groups: flight (F), basal (BC) and delayed synchronous (SC) controls. In M3 there were 5 females in each group. The animals were euthanized and examined using traditional histology, immunohistochemistry and X-ray microtomography. Mallory, Nissl and hematoxylin-eosin staining were used to compare the condition of brain, heart, liver, pancreas, spleen and small intestine. Brain and pancreas were also studied immunohistochemically. Behavior was registered by video camera in F and SC (M3). Thus we confirm the previous assumption that geckoes can preserve in weightlessness their ability to fi x themselves to the surfaces by their toe pads. We did not reveal in liver, pancreas, spleen and small intestine of F-M3 geckoes such evident changes like in F-M2 group. Glial destruction was detected immunohistochemically in the brains of F-M3 geckoes, especially in the cortical structures and epithalamus. Gluckocorticoids level for geckoes' feces in F-M2 was 4 times higher than in SC-M2 whereas the results for M3 were almost the same. Microtomografi c analysis of the femur bones showed some redistribution of the trabeculae in F-M3 group which occured in the direction from the outer compact bone to the bone center. Thus we conclude that in most structures of F-M3 animals the changes were less then in F-M2 ones. It can be explaned by shorter duration of M3 flight, higer temperature and the presence of water source. More prolonged experiments with larger groups of geckoes are necessary to verify the obtained data. Probably geckoes are well preadapted to conditions of spaceflight due to their specific biology.

  16. Arboreal Day Geckos (Phelsuma madagascariensis Differentially Modulate Fore- and Hind Limb Kinematics in Response to Changes in Habitat Structure.

    Directory of Open Access Journals (Sweden)

    Mingna V Zhuang

    Full Text Available By using adhesion, geckos can move through incredibly challenging habitats. However, continually changing terrain may necessitate modulation of the adhesive apparatus in order to maximize its effectiveness over a range of challenges. Behaviorally modulating how the adhesive system is applied can occur by altering the alignment of the foot relative to the long axis of the body and/or the angles between the digits (interdigital angle. Given the directionality of the adhesive system, geckos likely vary the application of the system via these mechanisms as they run. We quantified 3D movements (using high-speed video of the day gecko, Phelsuma madagascariensis, running on a range of ecologically relevant inclines (0°, 45°, 90° and perch diameters (1.5 cm, 10 cm and broad. We measured the instantaneous sum of interdigital angles and foot alignment relative to the body, as well as other kinematic variables, throughout each stride and across treatments. Modulation of foot alignment at 45° and 90° was similar between the forelimb and hind limb, but differed at 0°, suggesting that P. madagascariensis is able to exert an adhesive force using multiple strategies. Both the sum of interdigital angles and alignment in the fore- and hind foot were modulated. Differences in modulation between the limbs are likely related to the underlying morphology. The modulation of interdigital angle and foot alignment suggests that aspects other than the mechanism of adhesion, such as joint morphology, are important for arboreal movement in geckos. Our study of foot usage in arboreal locomotion reveals patterns that may be widespread across pad-bearing lizards. In addition to understanding the constraints exerted by the adhesive apparatus, we highlight how biomechanical traits may respond to the evolution of novel adaptations and morphologies.

  17. Arboreal Day Geckos (Phelsuma madagascariensis) Differentially Modulate Fore- and Hind Limb Kinematics in Response to Changes in Habitat Structure.

    Science.gov (United States)

    Zhuang, Mingna V; Higham, Timothy E

    2016-01-01

    By using adhesion, geckos can move through incredibly challenging habitats. However, continually changing terrain may necessitate modulation of the adhesive apparatus in order to maximize its effectiveness over a range of challenges. Behaviorally modulating how the adhesive system is applied can occur by altering the alignment of the foot relative to the long axis of the body and/or the angles between the digits (interdigital angle). Given the directionality of the adhesive system, geckos likely vary the application of the system via these mechanisms as they run. We quantified 3D movements (using high-speed video) of the day gecko, Phelsuma madagascariensis, running on a range of ecologically relevant inclines (0°, 45°, 90°) and perch diameters (1.5 cm, 10 cm and broad). We measured the instantaneous sum of interdigital angles and foot alignment relative to the body, as well as other kinematic variables, throughout each stride and across treatments. Modulation of foot alignment at 45° and 90° was similar between the forelimb and hind limb, but differed at 0°, suggesting that P. madagascariensis is able to exert an adhesive force using multiple strategies. Both the sum of interdigital angles and alignment in the fore- and hind foot were modulated. Differences in modulation between the limbs are likely related to the underlying morphology. The modulation of interdigital angle and foot alignment suggests that aspects other than the mechanism of adhesion, such as joint morphology, are important for arboreal movement in geckos. Our study of foot usage in arboreal locomotion reveals patterns that may be widespread across pad-bearing lizards. In addition to understanding the constraints exerted by the adhesive apparatus, we highlight how biomechanical traits may respond to the evolution of novel adaptations and morphologies.

  18. Effects of humidity on the mechanical properties of gecko setae.

    Science.gov (United States)

    Prowse, Michael S; Wilkinson, Matt; Puthoff, Jonathan B; Mayer, George; Autumn, Kellar

    2011-02-01

    We tested the hypothesis that an increase in relative humidity (RH) causes changes in the mechanical properties of the keratin of adhesive gecko foot hairs (setae). We measured the effect of RH on the tensile deformation properties, fracture, and dynamic mechanical response of single isolated tokay gecko setae and strips of the smooth lamellar epidermal layer. The mechanical properties of gecko setae were strongly affected by RH. The complex elastic modulus (measured at 5 Hz) of a single seta at 80% RH was 1.2 GPa, only 39% of the value when dry. An increase in RH reduced the stiffness and increased the strain to failure. The loss tangent increased significantly with humidity, suggesting that water absorption produces a transition to a more viscous type of deformation. The influence of RH on the properties of the smooth epidermal layer was comparable with that of isolated seta, with the exception of stress at rupture. These values were two to four times greater for the setae than for the smooth layer. The changes in mechanical properties of setal keratin were consistent with previously reported increases in contact forces, supporting the hypothesis that an increase in RH softens setal keratin, which increases adhesion and friction. Copyright © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Reproductive cycle of the Namib giant ground gecko ...

    African Journals Online (AJOL)

    The reproductive cycle of the Namib giant ground gecko, Chondrodactylus angulifer, from southern Africa was described from a histological examination of gonadal material from museum specimens. Males followed a seasonal testicular cycle in which (based on available specimens) the major period of spermiogenesis ...

  20. The Adult Attachment Projective Picture System: integrating attachment into clinical assessment.

    Science.gov (United States)

    George, Carol; West, Malcolm

    2011-01-01

    This article summarizes the development and validation of the Adult Attachment Projective System (AAP), a measure we developed from the Bowlby-Ainsworth developmental tradition to assess adult attachment status. The AAP has demonstrated excellent concurrent validity with the Adult Attachment Interview (George, Kaplan, & Main, 1984/1985/1996; Main & Goldwyn, 1985-1994; Main, Goldwyn, & Hesse, 2003), interjudge reliability, and test-retest reliability, with no effects of verbal intelligence or social desirability. The AAP coding and classification system and application in clinical and community samples are summarized. Finally, we introduce the 3 other articles that are part of this Special Section and discuss the use of the AAP in therapeutic assessment and treatment.

  1. High Diversity of Hepatozoon spp. in Geckos of the Genus Tarentola.

    Science.gov (United States)

    Tomé, Beatriz; Rato, Catarina; Harris, D James; Perera, Ana

    2016-08-01

    :   Hemogregarines are the most-commonly reported hemoparasites in reptiles. In this work we analyzed samples from 572 individuals of 6 species of the wall gecko genus Tarentola from European and African countries adjacent to the Mediterranean Sea as well as from the Macaronesian islands. Screening was done using hemogregarine-specific primers for the 18S rRNA gene. Positive amplifications were sequenced so that the diversity of the hemogregarines from these hosts could be assessed within a phylogenetic framework. The results from the phylogenetic analysis showed that within Tarentola, the detected parasites are comprised of at least 4 distinct main lineages of Hepatozoon spp. In clades A and B, the new sequences clustered closely together with the ones previously known from individuals of the genus Tarentola and other species of geckos but also with those from other vertebrate host groups including skinks, snakes, iguanids, and rodents. Clade C included a sample from Tarentola angustimentalis of the Canary Islands. This sequence is the first molecular characterization of these hemogregarines in this archipelago. Until now, this lineage had only been found in lacertids, skinks, and snakes, so this infection extends the host range for this clade. Lastly, in the newly detected clade D, the retrieved parasite sequences form a group currently identified as exclusive of geckos. Our results show that geckos of Tarentola spp. harbor a great diversity of hemogregarines but also that further sampling and other tools, including a multi-locus approach using faster-evolving genetic markers, and identification of definitive hosts are needed to better understand the biology, diversity, and distribution of these parasites.

  2. Tropical House Gecko (Hemidactylus mabouia predation on brown spiders (Loxosceles intermedia

    Directory of Open Access Journals (Sweden)

    E.N. Ramires

    2004-01-01

    Full Text Available Brown spiders (Loxosceles spp. are venomous arachnids, successfully adapted to urban habitats in Brazil. Loxoscelism became a serious public health problem in Paraná State, especially at the capital Curitiba, where the most abundant species is Loxosceles intermedia. Hemidactylus mabouia (Gekkonidae lizards are synanthropic predators of arthropods. In this paper, we describe the predatory behavior of the Tropical House Gecko H. mabouia on L. intermedia under laboratory conditions. Twelve geckos were observed, and all of them fed on brown spiders (n=123 observations. The attack consisted of a fast run followed by one bite on the spider’s abdomen or legs. The geckos did not attack L. intermedia anterior body parts, probably due to the fangs present in this region. Two Hemidactylus individuals were killed by L. intermedia bites: during a predatory encounter, and by an induced bite on a restrained lizard. The observations summarized in this paper show that H. mabouia could be used in the biological control of Loxosceles populations in human dwellings. However, additional field studies are necessary to quantify the impact of H. mabouia predation on urban populations of L. intermedia and other species of the same genus.

  3. Increased capacity for sustained locomotion at low temperature in parthenogenetic geckos of hybrid origin.

    Science.gov (United States)

    Kearney, Michael; Wahl, Rebecca; Autumn, Kellar

    2005-01-01

    The evolution of parthenogenesis is typically associated with hybridization and polyploidy. These correlates of parthenogenesis may have important physiological consequences that need be taken into account in understanding the relative merits of sexual and parthenogenetic reproduction. We compared the thermal sensitivity of aerobically sustained locomotion in hybrid/triploid parthenogenetic races of the gecko Heteronotia binoei and their diploid sexual progenitors. Endurance times at low temperature (10 degrees , 12.5 degrees , and 15 degrees C, 0.05 km h(-1)) were significantly greater in parthenogenetic females than in sexual females. Comparison of oxygen consumption rates during sustained locomotion at increasing speeds (0.05, 0.10, 0.15, 0.20, 0.25, and 0.30 km h(-1), 25 degrees C) indicated that parthenogenetic lizards have higher maximum oxygen consumption rates and maximum aerobic speeds than do female sexual geckos. In addition, parthenogenetic geckos showed greater levels of voluntary activity at 15 degrees C than did sexual geckos, although this pattern appears strongest in comparison to male sexual forms. Parthenogenetic lineages of Heteronotia thus have an advantage over sexual lineages in being capable of greater aerobic activity. This result is opposite of that found in prior studies of parthenogenetic teiid lizards (genus Cnemidophorus) and highlights the idiosyncratic nature of phenotypic evolution in parthenogens of hybrid origin.

  4. The attachment system in fledgling relationships: an activating role for attachment anxiety.

    Science.gov (United States)

    Eastwick, Paul W; Finkel, Eli J

    2008-09-01

    Is it sensible to study attachment dynamics between potential romantic partners before they share a full-fledged attachment bond? The present data indicate that such an approach may reveal novel insights about initial attraction processes. Four studies suggest that the state-like experience of attachment anxiety has functional implications within fledgling (i.e., desired or undeveloped) romantic relationships, well before the formation of an attachment bond. Studies 1 and 3 reveal that attachment anxiety directed toward a particular romantic interest is elevated before (in comparison with after) participants report being in an established relationship. Studies 2 and 3 demonstrate that such partner-specific attachment anxiety predicts attachment-relevant outcomes in fledgling relationships, including proximity seeking, safe haven, secure base, passionate love, and other approach behaviors. These associations were reliable above and beyond (and were typically as strong as or stronger than) the effect of sexual desire. Finally, Study 4 presents evidence that partner-specific attachment anxiety may cause several of these attachment-relevant outcomes. Attachment anxiety seems to be a normative experience and may signal the activation of the attachment system during the earliest stages of romantic relationships.

  5. Footprints in the sand: independent reduction of subdigital lamellae in the Namib–Kalahari burrowing geckos

    Science.gov (United States)

    Lamb, Trip; Bauer, Aaron M

    2005-01-01

    Many desert organisms exhibit convergence, and certain physical factors such as windblown sands have generated remarkably similar ecomorphs across divergent lineages. The burrowing geckos Colopus, Chondrodactylus and Palmatogecko occupy dune ecosystems in the Namib and Kalahari deserts of southwest Africa. Considered closely related, they share several putative synapomorphies, including reduced subdigital pads (toe pads) and spinose digital scales. Though recognized as part of Africa's ecologically diverse Pachydactylus Group, the burrowing geckos' precise phylogenetic affinities remain elusive. Convergent pedal modification provides a tenable alternative explaining the geckos' derived terrestriality and adaptation to Namib and Kalahari sands. We generated a molecular phylogeny for the Pachydactylus Group to examine evolutionary relationships among the burrowing geckos and infer historical patterns of pedal character change. Bayesian and parsimony analyses revealed all three burrowing genera to be deeply nested within Pachydactylus, each genus belonging to a separate clade. Strong support for these distinct clades indicates ecomorphological adaptations for burrowing have evolved independently three times in the southern Pachydactylus Group. We argue that the physical properties of Namib and Kalahari sands played a principal role in selecting for pedal similarity. PMID:16618680

  6. Wary invaders and clever natives: sympatric house geckos show disparate responses to predator scent

    OpenAIRE

    Adam Cisterne; Eric P. Vanderduys; David A. Pike; Lin Schwarzkopf

    2014-01-01

    The ability to detect and avoid potential predators can enhance fitness, but also has costs, and thus many animals respond to potential predators either in a general (avoid all potential predators) or threat-sensitive (selectively avoid dangerous predators) manner. We used 2-choice trials to investigate strategies used by globally invasive house geckos (Hemidactylus frenatus) and native Australian house geckos (Gehyra dubia) to avoid chemical cues from potential snake predators (Acanthophis a...

  7. Comparative analysis of the pituitary and ovarian GnRH systems in the leopard gecko: signaling crosstalk between multiple receptor subtypes in ovarian follicles.

    Science.gov (United States)

    Ikemoto, Tadahiro; Park, Min Kyun

    2007-02-01

    GnRH regulates reproductive functions through interaction with its pituitary receptor in vertebrates. The present study demonstrated that the leopard gecko possessed two and three genes for GnRH ligands and receptors, respectively, though one of the three receptor subtypes had long been thought not to exist in reptiles. Each receptor subtype showed a distinct pharmacology. All types of ligands and receptors showed different expression patterns, and were widely expressed both inside and outside the brain. This report also shows a comparison of the pituitary and ovarian GnRH systems in the leopard gecko during and after the egg-laying season. All three receptor subtypes were expressed in both the whole pituitary and ovary; however, only one receptor subtype could be detected in the anterior pituitary gland. In situ hybridization showed spatial expression patterns of ovarian receptors, and suggested co-expression of multiple receptor subtypes in granulosa cells of larger follicles. Co-transfection of receptor subtypes showed a distinct pharmacology in COS-7 cells compared with those of single transfections. These results suggest that distinct signaling mechanisms are involved in the pituitary and ovarian GnRH systems. Seasonal and developmental variations in receptor expression in the anterior pituitary gland and ovarian follicles may contribute to the seasonal breeding of this animal.

  8. Fuel rod attachment system

    International Nuclear Information System (INIS)

    Christiansen, D.W.

    1982-01-01

    A reusable system for removably attaching a nuclear reactor fuel rod to a support member. A locking cap is secured to the fuel rod and a locking strip is fastened to the support member or vice versa. The locking cap has two opposing fingers and shaped to form a socket having a body portion. The locking strip has an extension shaped to rigidly attach to the socket's body portion. The locking cap's fingers are resiliently deflectable. For attachment, the locking cap is longitudinally pushed onto the locking strip causing the extension to temporarily deflect open the fingers to engage the socket's body portion. For removal, the process is reversed. In an alternative embodiment, the cap is rigid and the strip is transversely resiliently compressible. (author)

  9. Comparison of subcutaneous dexmedetomidine-midazolam versus alfaxalone-midazolam sedation in leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Doss, Grayson A; Fink, Dustin M; Sladky, Kurt K; Mans, Christoph

    2017-09-01

    To compare dexmedetomidine-midazolam with alfaxalone-midazolam for sedation in leopard geckos (Eublepharis macularius). Prospective, randomized, blinded, complete crossover study. Nine healthy adult leopard geckos. Geckos were administered a combination of dexmedetomidine (0.1 mg kg -1 ) and midazolam (1.0 mg kg -1 ; treatment D-M) or alfaxalone (15 mg kg -1 ) and midazolam (1.0 mg kg -1 ; treatment A-M) subcutaneously craniodorsal to a thoracic limb. Heart rate (HR), respiratory rate (f R ), righting reflex, palpebral reflex, superficial and deep pain reflexes, jaw tone and escape response were assessed every 5 minutes until reversal. Conditions for intubation and response to needle prick were evaluated. Antagonist drugs [flumazenil (0.05 mg kg -1 ) ± atipamezole (1.0 mg kg -1 )] were administered subcutaneously, craniodorsal to the contralateral thoracic limb, 45 minutes after initial injection, and animals were monitored until recovery. HR, but not f R , decreased significantly over time in both treatments. HR was significantly lower than baseline at all time points in D-M and for all but the 5 and 10 minute time points in A-M. HR was significantly higher in A-M at all time points after drug administration when compared with D-M. Sedation scores between protocols were similar for most time points. All animals in A-M lost righting reflex compared with seven out of nine (78%) geckos in D-M. Geckos in A-M lost righting reflex for significantly longer time. Mean ± standard deviation time to recovery after antagonist administration was 6.1 ± 2.2 minutes for D-M and 56 ± 29 minutes for A-M, and these times were significantly different. Combination D-M or A-M provided sedation of a level expected to allow physical examinations and venipuncture in leopard geckos. A-M provided a faster onset of sedation compared with D-M. Recovery was significantly faster following antagonist reversal of D-M, compared with A-M. Copyright © 2017 Association of

  10. Adaptive simplification and the evolution of gecko locomotion: Morphological and biomechanical consequences of losing adhesion

    Science.gov (United States)

    Higham, Timothy E.; Birn-Jeffery, Aleksandra V.; Collins, Clint E.; Hulsey, C. Darrin; Russell, Anthony P.

    2015-01-01

    Innovations permit the diversification of lineages, but they may also impose functional constraints on behaviors such as locomotion. Thus, it is not surprising that secondary simplification of novel locomotory traits has occurred several times among vertebrates and could potentially lead to exceptional divergence when constraints are relaxed. For example, the gecko adhesive system is a remarkable innovation that permits locomotion on surfaces unavailable to other animals, but has been lost or simplified in species that have reverted to a terrestrial lifestyle. We examined the functional and morphological consequences of this adaptive simplification in the Pachydactylus radiation of geckos, which exhibits multiple unambiguous losses or bouts of simplification of the adhesive system. We found that the rates of morphological and 3D locomotor kinematic evolution are elevated in those species that have simplified or lost adhesive capabilities. This finding suggests that the constraints associated with adhesion have been circumvented, permitting these species to either run faster or burrow. The association between a terrestrial lifestyle and the loss/reduction of adhesion suggests a direct link between morphology, biomechanics, and ecology. PMID:25548182

  11. Attachment systems for mandibular implant overdentures: a systematic review

    Science.gov (United States)

    Kim, Ha-Young; Lee, Jeong-Yol; Bryant, S. Ross

    2012-01-01

    PURPOSE The aim of this systematic review was to address treatment outcome according to attachment systems for mandibular implant overdentures in terms of implant survival rate, prosthetic maintenance and complications, and patient satisfaction. MATERIALS AND METHODS A systematic literature search was conducted using PubMed and hand searching of relevant journals considering inclusion and exclusion criteria. Clinical trial studies on mandibular implant overdentures until August, 2010 were selected if more than one type of overdenture attachment was reported. Twenty four studies from 1098 studies were finally included and the data on implant survival rate, prosthetic maintenance and complications, patient satisfaction were analyzed relative to attachment systems. RESULTS Four studies presented implant survival rates (95.8 - 97.5% for bar, 96.2 - 100% for ball, 91.7% for magnet) according to attachment system. Ten other studies presented an implant survival rate ranging from 93.3% to 100% without respect to the attachment groups. Common prosthetic maintenance and complications were replacement of an assay for magnet attachments, and activation of a matrix or clip for ball or bar attachments. Prosthetic maintenance and complications most commonly occurred in the magnet groups. Conflicting findings were found on the rate of prosthetic maintenance and complications comparing ball and bar attachments. Most studies showed no significant differences in patient satisfaction depending upon attachment systems. CONCLUSION The implant survival rate of mandibular overdentures seemed to be high regardless attachment systems. The prosthetic maintenance and complications may be influenced by attachment systems. However patient satisfaction may be independent of the attachment system. PMID:23236571

  12. New Sarcocystis species with a snake-gecko life cycle

    Czech Academy of Sciences Publication Activity Database

    Šlapeta, J.; Modrý, D.; Koudela, Břetislav

    1998-01-01

    Roč. 45, č. 1 (1998), s. 7 ISSN 1066-5234. [New Sarcocystis species with a snake -gecko life cycle. 01.01.1998-02.01.1998, Praha] R&D Projects: GA ČR GA508/95/0273 Subject RIV: fp - Other Medical Disciplines

  13. Diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) at a veterinary teaching hospital: 52 cases (1985-2013).

    Science.gov (United States)

    Wiggans, K Tomo; Sanchez-Migallon Guzman, David; Reilly, Christopher M; Vergneau-Grosset, Claire; Kass, Philip H; Hollingsworth, Steven R

    2018-02-01

    OBJECTIVE To describe diagnosis, treatment, and outcome of and risk factors for ophthalmic disease in leopard geckos (Eublepharis macularius) evaluated at a veterinary teaching hospital. DESIGN Retrospective case series. ANIMALS 112 of 144 (78%) leopard geckos that were evaluated at a veterinary teaching hospital in January 1985 through October 2013 and for which sufficient medical record information was available. PROCEDURES Information from medical records was used to identify leopard geckos with ophthalmic disease, characterize cases, and determine risk factors for the presence of ophthalmic disease. RESULTS Of the 112 leopard geckos, 52 (46%) had ophthalmic disease (mainly corneal or conjunctival disease). Female geckos were less likely to have ophthalmic disease, and there was a positive association between increasing age and ophthalmic disease. Use of a paper towel substrate, absence of any heat source, and lack of vitamin A supplementation were positively associated with a diagnosis of ophthalmic disease. Head dysecdysis was the only concurrent disorder significantly associated with ophthalmic disease. At necropsy, 5 affected leopard geckos had squamous metaplasia of the conjunctivae. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that ophthalmic disease is a common finding in leopard geckos. The cause of ocular surface disease in leopard geckos may be multifactorial, and hypovitaminosis A may be an important risk factor. Although animals receiving supplemental vitamin A were less likely to have ophthalmic disease, further understanding is required regarding the metabolism of and nutritional requirements for vitamin A in leopard geckos.

  14. Generalization of predator recognition: Velvet geckos display anti-predator behaviours in response to chemicals from non-dangerous elapid snakes

    Directory of Open Access Journals (Sweden)

    Jonathan K. WEBB, Weiguo DU, David PIKE, Richard SHINE

    2010-06-01

    Full Text Available Many prey species detect chemical cues from predators and modify their behaviours in ways that reduce their risk of predation. Theory predicts that prey should modify their anti-predator responses according to the degree of threat posed by the predator. That is, prey should show the strongest responses to chemicals of highly dangerous prey, but should ignore or respond weakly to chemicals from non-dangerous predators. However, if anti-predator behaviours are not costly, and predators are rarely encountered, prey may exhibit generalised antipredator behaviours to dangerous and non-dangerous predators. In Australia, most elapid snakes eat lizards, and are therefore potentially dangerous to lizard prey. Recently, we found that the nocturnal velvet gecko Oedura lesueurii responds to chemicals from dangerous and non-dangerous elapid snakes, suggesting that it displays generalised anti-predator behaviours to chemicals from elapid snakes. To explore the generality of this result, we videotaped the behaviour of velvet geckos in the presence of chemical cues from two small elapid snakes that rarely consume geckos: the nocturnal golden-crowned snake Cacophis squamulosus and the diurnal marsh snake Hemiaspis signata. We also videotaped geckos in trials involving unscented cards (controls and cologne-scented cards (pungency controls. In trials involving Cacophis and Hemiaspis chemicals, 50% and 63% of geckos spent long time periods (> 3 min freezing whilst pressed flat against the substrate, respectively. Over half the geckos tested exhibited anti-predator behaviours (tail waving, tail vibration, running in response to Cacophis (67% or Hemiaspis (63% chemicals. These behaviours were not observed in control or pungency control trials. Our results support the idea that the velvet gecko displays generalised anti-predator responses to chemical cues from elapid snakes. Generalised responses to predator chemicals may be common in prey species that co-occur with

  15. Engineering Gecko-Inspired Adhesives for Robotic Mobility and Manipulation in Microgravity

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal of the proposed research is to customize gecko-inspired adhesive technologies for space applications in manipulation and mobility, primarily addressing...

  16. Reproduction in a gecko assemblage (Squamata: Phyllodactylidae in the Marañon Region (Peru and comments on the largest gecko in the New World

    Directory of Open Access Journals (Sweden)

    Janina Aurich

    2015-06-01

    Full Text Available Reproduction is described for four phyllodactylid geckos, Phyllopezus maranjonensis, Phyllodactylus delsolari, P. thompsoni and P. reissii from the upper Marañon Valley, Peru. Observations were made between March and May 2010 and voucher specimens, already housed in the Zoologisches Forschungsmuseum Alexander Koenig (ZFMK, were X-rayed to check for gravid females. Gravid female P. maranjonensis, P. delsolari and P. reissii contain two eggs, whereas P. thompsoni produces a single egg that is deposited in leaf litter or crevices of stone walls. It is likely that females of all of these species produce multiple clutches in one year; the reproductive period seems to be extended in at least two species. Furthermore, measurements of numerous specimens of all four species are presented herein, revealing that Phyllopezus maranjonensis is the largest species of New World geckos.

  17. Comparison of dietary overlap between allopatric and sympatric geckos

    Science.gov (United States)

    Paul D. Klawinski; R. Kathryn Vaughan; Daniel Saenz; William Godwin

    1994-01-01

    Two gecko species, Hemidactylus turcicus and Cyrtopodion scabrum, have been introduced into the Port of Galveston, Texas. While H. turcicus has been established for a longer period of time, the relatively recent introduction of C. scabrum near the entrance of the Port has apparently led to the...

  18. Quantitative anatomical basis for a model of micromechanical frequency tuning in the Tokay gecko, Gekko gecko.

    Science.gov (United States)

    Köppl, C; Authier, S

    1995-01-01

    The basilar papilla of the Tokay gecko was studied with standard light- and scanning electron microscopy methods. Several parameters thought to be of particular importance for the mechanical response properties of the system were quantitatively measured, separately for the three different hair-cell areas that are typical for this lizard family. In the basal third, papillar structure was very uniform. The apical two-thirds are subdivided into two hair-cell areas running parallel to each other along the papilla and covered by very different types of tectorial material. Both of those areas showed prominent gradients in hair-cell bundle morphology, i.e., in the height of the stereovillar bundles and the number of stereovilli per bundle, as well as in hair cell density and the size of their respective tectorial covering. Based on the direction of the observed anatomical gradients, a 'reverse' tonotopic organization is suggested, with the highest frequencies represented at the apical end.

  19. Posture, speed, and habitat structure: three-dimensional hindlimb kinematics of two species of padless geckos.

    Science.gov (United States)

    Fuller, Patrick O; Higham, Timothy E; Clark, Andrew J

    2011-04-01

    Differences in habitat use are often correlated with differences in morphology and behavior, while animals in similar habitats often exhibit similarities in form and function. However, this has not been tested extensively among lizards, especially geckos. Most studies of gecko locomotion have focused on the ability to adhere to surfaces. However, there are several species of geckos that have either secondarily lost adhesive capabilities or simply lack the capability. We quantified the three-dimensional locomotor kinematics for two desert-dwelling padless geckos, Teratoscincus scincus and Eublepharis macularius, on a level trackway over a range of speeds. Our results indicate that T. scincus landed with a high relative hip height of 48.7 ± 2.4% of total limb length at footfall, while E. macularius exhibited hip heights averaging only 36.0 ± 1.8% of total limb length for footfall. The three-dimensional knee angle of T. scincus averaged 120.6 ± 3.9° at footfall, while E. macularius averaged only 101.6 ± 1.8° at footfall. In addition, the femur of E. macularius was elevated to a much greater extent (i.e., was closer to being perpendicular to the long axis of the body) than that of T. scincus and every other lizard that has been studied, suggesting they move with a "hyper-sprawled" posture. Both of these gecko species live in deserts, but T. scincus is psammophilic while E. macularius inhabits a rocky, more densely vegetated environment. Benefits of the more upright posture of T. scincus on open sandy habitat may include a greater field of view and more efficient locomotion. The more sprawled posture of E. macularius may lower its center of gravity and aid in balance while climbing on rocks or shrubs. Copyright © 2011 Elsevier GmbH. All rights reserved.

  20. How do the substrate reaction forces acting on a gecko's limbs respond to inclines?

    Science.gov (United States)

    Wang, Zhouyi; Dai, Zhendong; Li, Wei; Ji, Aihong; Wang, Wenbao

    2015-02-01

    Locomotion is an essential character of animals, and excellent moving ability results from the delicate sensing of the substrate reaction forces (SRF) acting on body and modulating the behavior to adapt the motion requirement. The inclined substrates present in habitats pose a number of functional challenges to locomotion. In order to effectively overcome these challenges, climbing geckos execute complex and accurate movements that involve both the front and hind limbs. Few studies have examined gecko's SRF on steeper inclines of greater than 90°. To reveal how the SRFs acting on the front and hind limbs respond to angle incline changes, we obtained detailed measurements of the three-dimensional SRFs acting on the individual limbs of the tokay gecko while it climbed on an inclined angle of 0-180°. The fore-aft forces acting on the front and hind limbs show opposite trends on inverted inclines of greater than 120°, indicating propulsion mechanism changes in response to inclines. When the incline angles change, the forces exerted in the normal and fore-aft directions by gecko's front and hind limbs are reassigned to take full advantage of limbs' different roles in overcoming resistance and in propelling locomotion. This also ensures that weight acts in the angle range between the forces generated by the front and hind limbs. The change in the distribution of SRF with a change in the incline angle is directly linked to the favorable trade-off between locomotive maneuverability and stability.

  1. Amount of prenatal visual stimulation alters incubation times and postnatal preferences in leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Sleigh, M J; Birchard, G F

    2001-09-01

    The authors exposed gecko (Eublepharis macularius) embryos to patterned visual stimulation beginning at either 1 week or 2 weeks prior to hatching. Embryos exposed to the substantially augmented amount of prenatal visual stimulation hatched significantly earlier than the embryos either exposed to the moderately augmented prenatal visual stimulation or not exposed to any prenatal visual stimulation (p geckos in all conditions failed to exhibit a preference for either stimulus.

  2. Primer caso de canibalismo registrado para el gecko de Lima, Phyllodactylus sentosus (Reptilia, Phyllodactylidae)

    OpenAIRE

    Valdez, Fernando; Cossios, E. Daniel

    2017-01-01

    Se reporta un caso de canibalismo en el gecko de Lima, Phyllodactylus sentosus Dixon & Huey, 1970 donde un macho adulto devoró a un juvenil. Tras una búsqueda de literatura, no se encontró casos reportados en otras especies del mismo género, por lo que se considera que este es el primer reporte de canibalismo en Phyllodactylus. We report a case of cannibalism for the Lima leaf-toed gecko, Phyllodactylus sentosus, in which an adult male devoured a juvenile. No reported cases were found in o...

  3. Molecular cloning of P450 aromatase from the leopard gecko and its expression in the ovary.

    Science.gov (United States)

    Endo, Daisuke; Park, Min Kyun

    2005-07-01

    In this study, we identified the cDNA of P450 aromatase in the leopard gecko, a lizard with temperature-dependent sex determination. The cDNA encodes a putative protein of 505 amino acids. The deduced amino acid sequence of leopard gecko aromatase cDNA showed 80% identity with that of turtles, 70% with humans and 77% with chickens. This is the first report of the identification of P450 aromatase cDNA in squamata species. It has been reported that this gene is expressed in different layers of cells in the ovary of mammalian species and avian species. Thus, we also investigated cells expressing the mRNA of this gene in the ovary of the leopard gecko by RT-PCR and in situ hybridization. The mRNA expression of leopard gecko P450 aromatase was localized in both the thecal and granulosa cell layers in the ovary. The expression in thecal and granulosa cell layers was examined in the largest follicle, second largest follicle and third largest follicle by RT-PCR. A higher level of mRNA expression was observed in the granulosa cell layer of the second largest follicle than in other cell layers. This result may reflect the characteristics of follicles in species with automonochronic ovulation.

  4. Patterns of diversification in islands: A comparative study across three gecko genera in the Socotra Archipelago.

    Science.gov (United States)

    Garcia-Porta, Joan; Morales, Hernán E; Gómez-Díaz, Elena; Sindaco, Roberto; Carranza, Salvador

    2016-05-01

    In this study we used the complete fauna of geckos of the Socotra Archipelago to test whether the three gecko genera co-occurring in the islands (Pristurus, Hemidactylus and Haemodracon) produced similar outcomes of morphological and climatic diversification. To test this, we produced a time-calibrated tree of 346 geckos including all 16 endemic species of the archipelago and 26 potential close-relatives in the continent. Our dating estimates revealed that most of the diversity of geckos in the archipelago was the consequence of in situ diversification. However not all genera shared similar patterns of diversification. While in Hemidactylus and Haemodracon this involved great differences in body size and low levels of climatic diversification (mostly involving sympatric distributions), an opposite pattern appeared in Pristurus in which most of the diversification involved shifts in climatic envelopes (mostly involving allopatric and parapatric distributions) but almost no size differentiation. Consistently with this, Pristurus was the only genus in which rates of size diversification in islands were substantially lower than in the continent. This illustrates how different groups can greatly differ in their patterns of intra-island diversification and highlights the importance of taxon-dependent factors at determining different patterns of diversification in the same insular context. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Dermatitis and cellulitis in leopard geckos (Eublepharis macularius) caused by the Chrysosporium anamorph of Nannizziopsis vriesii.

    Science.gov (United States)

    Toplon, D E; Terrell, S P; Sigler, L; Jacobson, E R

    2013-07-01

    An epizootic of ulcerative to nodular ventral dermatitis was observed in a large breeding colony of 8-month to 5-year-old leopard geckos (Eublepharis macularius) of both sexes. Two representative mature male geckos were euthanized for diagnostic necropsy. The Chrysosporium anamorph of Nannizziopsis vriesii (CANV) was isolated from the skin lesions, and identification was confirmed by sequencing of the internal transcribed spacer region of the rRNA gene. Histopathology revealed multifocal to coalescing dermal and subcutaneous heterophilic granulomas that contained septate fungal hyphae. There was also multifocal epidermal hyperplasia with hyperkeratosis, and similar hyphae were present within the stratum corneum, occasionally with terminal chains of arthroconidia consistent with the CANV. In one case, there was focal extension of granulomatous inflammation into the underlying masseter muscle. This is the first report of dermatitis and cellulitis due to the CANV in leopard geckos.

  6. Expression of sex steroid hormone-related genes in the embryo of the leopard gecko.

    Science.gov (United States)

    Endo, Daisuke; Kanaho, Yoh-Ichiro; Park, Min Kyun

    2008-01-01

    Sex steroid hormones are known to play a central role in vertebrate sex determination and differentiation. However, the tissues in which they are produced or received during development, especially around the period of sex determination of the gonads, have rarely been investigated. In this study, we identified the cDNA sequence, including the full-length of the coding region of cholesterol side-chain cleavage enzyme (P450scc), from the leopard gecko; a lizard with temperature-dependent sex determination. Embryonic expression analysis of two steroidogenic enzymes, P450scc and P450 aromatase (P450arom), and four sex steroid hormone receptors, androgen receptor, estrogen receptor alpha and beta, and progesterone receptor, was subsequently conducted. mRNA expression of both steroidogenic enzymes was observed in the brain and gonads prior to the temperature-sensitive period of sex determination. The mRNAs of the four sex steroid hormone receptors were also detected in the brain and gonads at all stages examined. These results suggest the existence of a gonad-independent sex steroid hormone signaling system in the developing leopard gecko brain.

  7. The mitochondrial genomes of Atlas Geckos (Quedenfeldtia): mitogenome assembly from transcriptomes and anchored hybrid enrichment datasets

    OpenAIRE

    Lyra, Mariana L.; Joger, Ulrich; Schulte, Ulrich; Slimani, Tahar; El Mouden, El Hassan; Bouazza, Abdellah; Künzel, Sven; Lemmon, Alan R.; Moriarty Lemmon, Emily; Vences, Miguel

    2017-01-01

    The nearly complete mitogenomes of the two species of North African Atlas geckos, Quedenfeldtia moerens and Q. trachyblepharus were assembled from anchored hybrid enrichment data and RNAseq data. Congruent assemblies were obtained for four samples included in both datasets. We recovered the 13 protein-coding genes, 22 tRNA genes, and two rRNA genes for both species, including partial control region. The order of genes agrees with that of other geckos.

  8. Reversed tonotopic map of the basilar papilla in Gekko gecko.

    Science.gov (United States)

    Manley, G A; Köppl, C; Sneary, M

    1999-05-01

    A published model of the frequency responses of different locations on the basilar papilla of the Tokay gecko Gekko gecko (Authier and Manley, 1995. Hear. Res. 82, 1-13) had implied that (a) unlike all other amniotes studied so far, the frequency map is reversed, with the low frequencies at the base and the high frequencies at the apex, and (b) the high-frequency area is split into two parallel-lying hair cell areas covering different frequency ranges. To test these hypotheses, the frequency representation along the basilar papilla of Gekko gecko was studied by recording from single auditory afferent nerve fibers and labelling them iontophoretically with horseradish peroxidase. Successfully labelled fibers covered a range of characteristic frequencies from 0.42 to 4.9 kHz, which extended from 78% to 9% of the total papillar length, as measured from the apex. The termination sites of labelled fibers within the basilar papilla correlated with their characteristic frequency, the lowest frequencies being represented basally, and the highest apically. This confirms the first prediction of the model. The map indicates, however, that one of the two high-frequency papillar regions (the postaxial segment) represents the full high-frequency range, from about 1 to 5 kHz. No functionally identified labelling was achieved in the preaxial segment. Thus the assumptions underlying the proposed model need revision. A good mathematical description of the frequency distribution was given by an exponential regression with a mapping constant in the living state of approximately 0.4 mm/octave.

  9. Mechanisms of spectral tuning in the RH2 pigments of Tokay gecko and American chameleon

    OpenAIRE

    Takenaka, Naomi; Yokoyama, Shozo

    2007-01-01

    At present, molecular bases of spectral tuning in rhodopsin-like (RH2) pigments are not well understood. Here, we have constructed the RH2 pigments of nocturnal Tokay gecko (Gekko gekko) and diurnal American chameleon (Anolis carolinensis) as well as chimeras between them. The RH2 pigments of the gecko and chameleon reconstituted with 11-cis-retinal had the wavelengths of maximal absorption (λmax’s) of 467 and 496 nm, respectively. Chimeric pigment analyses indicated that 76–86%, 14–24%, and ...

  10. Preliminary results on tail energetics in the Moorish gecko, Tarentola mauritanica

    Directory of Open Access Journals (Sweden)

    Tommaso Cencetti

    2011-06-01

    Full Text Available The amount of lipids, proteins, ashes and water in original versus regenerated tails in Tarentola mauritanica shows differences, especially on the lipid fraction, supporting adaptive function hypotheses during reproduction of regenerated tails in geckos.

  11. Colonisation of epiphytic ferns by skinks and geckos in the high canopy of a Bornean rainforest

    OpenAIRE

    Donald, J.; Clegg, J.; Ellwood, M. D. F.

    2017-01-01

    Nest site availability limits the fitness and survival of skinks and geckos, particularly in the canopy of tall tropical rainforests. We document the systematic colonisation and nest use of epiphytic bird’s nest ferns (Asplenium spp) by the gecko Hemiphyllodactylus typus and the skink Lipinia cf. vittigera. As part of a controlled experiment we placed 32 ferns of similar sizes in the high canopy of a lowland dipterocarp rainforest in Sabah, Malaysian Borneo. Half of these ferns, sampled after...

  12. Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos

    Directory of Open Access Journals (Sweden)

    Raquel Vasconcelos

    2017-01-01

    Full Text Available Background The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals of the same species, respectively. As most lizards are territorial, aggregations increase the probability of aggressive interactions among individuals, a density-dependent behaviour. Methods After some spurious observations of aggregation behaviour in the endemic Cabo Verde nocturnal gecko Tarentola substituta, we conducted a field-based study in order to thoroughly characterize it. We sampled 48 transects and 40 10 × 10 m quadrats on São Vicente Island to describe the incidence, size and composition of aggregations and to study the effect of gecko and refuge density, plus refuge quality, on refuge sharing. We hypothesize that when density of animals and scarcity of high-quality refuges is higher, lizards have increased probability of aggregating. We also predict a consistent pattern of size and composition of groups (male–female pairs, only one adult male per group throughout the year if there is a selected behaviour to avoid agonistic interactions, and low thermal advantage to aggregating individuals. Results We present one of the first evidences of aggregation for Phyllodactylidae geckos. We found that T. substituta forms aggregations around 30–40% of the time, and that refuges are almost always shared by a female-male pair, sometimes with a juvenile, probably a mechanism to avoid aggressive interactions. We also observed that refuge sharing is dependent on refuge quality, as medium–large (thermally more stable and positively selected rocks are shared much more frequently than small ones, but independent of adult sizes. Refuge sharing is also directly related to the density of geckos and inversely related to the density of high-quality refuges. We found no relation between body temperatures of geckos and refuge sharing when

  13. Sharing refuges on arid islands: ecological and social influence on aggregation behaviour of wall geckos.

    Science.gov (United States)

    Vasconcelos, Raquel; Rocha, Sara; Santos, Xavier

    2017-01-01

    The extent of social behaviour among reptiles is underappreciated. Two types of aggregations are recognized in lizards: ecological and social, i.e., related to the attraction to a site or to animals of the same species, respectively. As most lizards are territorial, aggregations increase the probability of aggressive interactions among individuals, a density-dependent behaviour. After some spurious observations of aggregation behaviour in the endemic Cabo Verde nocturnal gecko Tarentola substituta, we conducted a field-based study in order to thoroughly characterize it. We sampled 48 transects and 40 10 × 10 m quadrats on São Vicente Island to describe the incidence, size and composition of aggregations and to study the effect of gecko and refuge density, plus refuge quality, on refuge sharing. We hypothesize that when density of animals and scarcity of high-quality refuges is higher, lizards have increased probability of aggregating. We also predict a consistent pattern of size and composition of groups (male-female pairs, only one adult male per group) throughout the year if there is a selected behaviour to avoid agonistic interactions, and low thermal advantage to aggregating individuals. We present one of the first evidences of aggregation for Phyllodactylidae geckos. We found that T. substituta forms aggregations around 30-40% of the time, and that refuges are almost always shared by a female-male pair, sometimes with a juvenile, probably a mechanism to avoid aggressive interactions. We also observed that refuge sharing is dependent on refuge quality, as medium-large (thermally more stable and positively selected) rocks are shared much more frequently than small ones, but independent of adult sizes. Refuge sharing is also directly related to the density of geckos and inversely related to the density of high-quality refuges. We found no relation between body temperatures of geckos and refuge sharing when controlling the effect of rock/air temperature

  14. Spectral transmittance of the spectacle scale of snakes and geckos

    NARCIS (Netherlands)

    Doorn, van K.; Sivak, J.G.

    2015-01-01

    The spectral transmittance of the optical media of the eye plays a substantial role in tuning the spectrum of light available for capture by the retina. Certain squamate reptiles, including snakes and most geckos, shield their eyes beneath a layer of transparent, cornified skin called the

  15. Reverse adhesion of a gecko-inspired synthetic adhesive switched by an ion-exchange polymer-metal composite actuator.

    Science.gov (United States)

    Guo, Dong-Jie; Liu, Rui; Cheng, Yu; Zhang, Hao; Zhou, Li-Ming; Fang, Shao-Ming; Elliott, Winston Howard; Tan, Wei

    2015-03-11

    Inspired by how geckos abduct, rotate, and adduct their setal foot toes to adhere to different surfaces, we have developed an artificial muscle material called ion-exchange polymer-metal composite (IPMC), which, as a synthetic adhesive, is capable of changing its adhesion properties. The synthetic adhesive was cast from a Si template through a sticky colloid precursor of poly(methylvinylsiloxane) (PMVS). The PMVS array of setal micropillars had a high density of pillars (3.8 × 10(3) pillars/mm(2)) with a mean diameter of 3 μm and a pore thickness of 10 μm. A graphene oxide monolayer containing Ag globular nanoparticles (GO/Ag NPs) with diameters of 5-30 nm was fabricated and doped in an ion-exchanging Nafion membrane to improve its carrier transfer, water-saving, and ion-exchange capabilities, which thus enhanced the electromechanical response of IPMC. After being attached to PMVS micropillars, IPMC was actuated by square wave inputs at 1.0, 1.5, or 2.0 V to bend back and forth, driving the micropillars to actively grip or release the surface. To determine the adhesion of the micropillars, the normal adsorption and desorption forces were measured as the IPMC drives the setal micropillars to grip and release, respectively. Adhesion results demonstrated that the normal adsorption forces were 5.54-, 14.20-, and 23.13-fold higher than the normal desorption forces under 1.0, 1.5, or 2.0 V, respectively. In addition, shear adhesion or friction increased by 98, 219, and 245%, respectively. Our new technique provides advanced design strategies for reversible gecko-inspired synthetic adhesives, which might be used for spiderman-like wall-climbing devices with unprecedented performance.

  16. Sociosexual Investigation in Sexually Experienced, Hormonally Manipulated Male Leopard Geckos: Relation With Phosphorylated DARPP-32 in Dopaminergic Pathways

    OpenAIRE

    HUANG, VICTORIA; HEMMINGS, HUGH C.; CREWS, DAVID

    2014-01-01

    Dopaminergic activity is both associated with sociosexual exposure and modulated by sexual experience and hormonal state across vertebrate taxa. Mature leopard geckos, a reptile with temperature-dependent sex determination, have dopaminoceptive nuclei that are influenced by their embryonic environment and sensitive to adult hormonal manipulation. In this study, we exposed hormonally manipulated male leopard geckos from different incubation temperatures to conspecifics and measured their socio...

  17. Characterisation and expression of Sox9 in the Leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Valleley, E M; Cartwright, E J; Croft, N J; Markham, A F; Coletta, P L

    2001-04-15

    Since the discovery of the sex-determining gene, Sry, a number of genes have been identified which are involved in sex determination and gonadogenesis in mammals. Although Sry is known to be the testis-determining factor in mammals, this is not the case in non-mammalian vertebrates. Sox9 is another gene that has been shown to have a male-specific role in sex determination, but, unlike Sry, Sox9 has been shown to be involved in sex determination in mammals, birds, and reptiles. This is the first gene to be described that has a conserved role in sex determination in species with either chromosomal or environmental sex-determining mechanisms. Many reptiles do not have sex chromosomes but exhibit temperature-dependent sex determination (TSD). Sox9 has been shown to be expressed in both turtle and alligator during gonadogenesis. To determine if Sox9 also has a role in a gecko species with TSD, we studied gonadal expression of Sox9 during embryonic development of the Leopard gecko (Eublepharis macularius). Gecko Sox9 was found to be highly conserved at the nucleotide level when compared to other vertebrate species including human, chick, alligator, and turtle. Sox9 was found to be expressed in embryos incubated at the male-producing temperature (32.5 degrees C) as well as in embryos incubated at the female-producing temperatures (26 and 34 degrees C), Northern blot analysis showed that Sox9 was expressed at both temperatures from morphological stages 31 to 37. mRNA in situ hybridisation on isolated urogenital systems showed expression at both female- and male-producing temperatures up to stage 36. After this stage, no expression was seen in the female gonads but expression remained in the male. These data provide further evidence that Sox9 is an essential component of a testis-determining pathway that is conserved in species with differing sex-determining mechanisms.

  18. The Role of Surface Chemistry in Adhesion and Wetting of Gecko Toe Pads

    Science.gov (United States)

    Badge, Ila; Stark, Alyssa Y.; Paoloni, Eva L.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2014-10-01

    An array of micron-sized setal hairs offers geckos a unique ability to walk on vertical surfaces using van der Waals interactions. Although many studies have focused on the role of surface morphology of the hairs, very little is known about the role of surface chemistry on wetting and adhesion. We expect that both surface chemistry and morphology are important, not only to achieve optimum dry adhesion but also for increased efficiency in self-cleaning of water and adhesion under wet conditions. Here, we used a plasma-based vapor deposition process to coat the hairy patterns on gecko toe pad sheds with polar and non-polar coatings without significantly perturbing the setal morphology. By a comparison of wetting across treatments, we show that the intrinsic surface of gecko setae has a water contact angle between 70-90°. As expected, under wet conditions, adhesion on a hydrophilic surface (glass) was lower than that on a hydrophobic surface (alkyl-silane monolayer on glass). Surprisingly under wet and dry conditions the adhesion was comparable on the hydrophobic surface, independent of the surface chemistry of the setal hairs. This work highlights the need to utilize morphology and surface chemistry in developing successful synthetic adhesives with desirable adhesion and self-cleaning properties.

  19. Nuclear reactor fuel rod attachment system

    International Nuclear Information System (INIS)

    Christiansen, D.W.

    1983-01-01

    The invention involves a technique to quickly, inexpensively and rigidly attach a nuclear reactor fuel rod to a support member. The invention also allows for the repeated non-destructive removal and replacement of the fuel rod. The proposed fuel rod and support member attachment and removal system consists of a locking cap fastened to the fuel rod and a locking strip fastened to the support member or vice versa. The locking cap has two or more opposing fingers shaped to form a socket. The fingers spring back when moved apart and released. The locking strip has an extension shaped to rigidly attach to the socket's body portion

  20. Molecular characterization of the leopard gecko POMC gene and expressional change in the testis by acclimation to low temperature and with a short photoperiod.

    Science.gov (United States)

    Endo, Daisuke; Park, Min Kyun

    2004-08-01

    The gene for proopiomelanocortin (POMC), a common precursor of malanotropins, corticotropin, and beta-endorphin, was isolated and analyzed in the squamata species, the leopard gecko, Eublepharis macularius. Leopard gecko POMC (lgPOMC) cDNA is composed of 1299bp, excluding the poly(A) tail, and encodes 270 amino acids. The deduced amino acid sequence showed the same structural organization as that of other species and displayed identity with those of other vertebrates: 68% with mud turtles, 57/57% with African clawed frog A/B, 53% with chickens, and 45% with mice. In a phylogenic tree, the lgPOMC clustered with the sequences of the mud turtle POMC and python POMC. The lgPOMC gene comprises three exons and two introns and this structure is consistent with humans, rats, mice, African clawed frog and zebrafish. RT-PCR analysis revealed that the lgPOMC mRNA was expressed only in the whole brain, pituitary, and gonads. To analyze in more detail, a competitive assay system to quantify the expression levels of POMC mRNA was established. We measured the POMC mRNA expression levels in the leopard gecko testes following transfer from a condition of 29 degrees C, 16L/8D to 18 degrees C, 10L/14D over 6 weeks. This 6-week acclimation increased the POMC mRNA expression levels significantly. This suggests that the leopard gecko POMC-derived peptides play a role in the mediation of the effect of environmental factors on reproduction.

  1. Early photolysis intermediates of gecko and bovine artificial visual pigments.

    Science.gov (United States)

    Lewis, J W; Liang, J; Ebrey, T G; Sheves, M; Livnah, N; Kuwata, O; Jäger, S; Kliger, D S

    1997-11-25

    Nanosecond laser photolysis measurements were conducted on digitonin extracts of artificial pigments prepared from the cone-type visual pigment, P521, of the Tokay gecko (Gekko gekko) retina. Artificial pigments were prepared by regeneration of bleached gecko photoreceptor membranes with 9-cis-retinal, 9-cis-14-methylretinal, or 9-cis-alpha-retinal. Absorbance difference spectra were recorded at a sequence of time delays from 30 ns to 60 microseconds following excitation with a pulse of 477-nm actinic light. Global analysis showed the kinetic data for all three artificial gecko pigments to be best fit by two-exponential processes. These two-exponential decays correspond to similar decays observed after photolysis of P521 itself, with the first process being the decay of the equilibrated P521 BathoP521 BSI mixture to P521 Lumi and the second process being the decay of P521 Lumi to P521 Meta I. In spite of its large blue shift relative to P521, iso-P521 displays a normal chloride depletion induced blue shift. Iso-P521's early intermediates up to Lumi were also blue-shifted, with the P521 BathoP521 BSI equilibrated mixture being 15 nm blue-shifted and P521 Lumi being 8 nm blue-shifted relative to the intermediates formed after P521 photolysis. The blue shift associated with the iso-pigment is reduced or disappears entirely by P521 Meta I. Similar blue shifts were observed for the early intermediates observed after photolysis of bovine isorhodopsin, with the Lumi intermediate blue-shifted 5 nm compared to the Lumi intermediate formed after photolysis of bovine rhodopsin. These shifts indicate that a difference exists between the binding sites of 9- and 11-cis pigments which persists for microseconds at 20 degrees C.

  2. Evolution of gliding in Southeast Asian geckos and other vertebrates is temporally congruent with dipterocarp forest development.

    Science.gov (United States)

    Heinicke, Matthew P; Greenbaum, Eli; Jackman, Todd R; Bauer, Aaron M

    2012-12-23

    Gliding morphologies occur in diverse vertebrate lineages in Southeast Asian rainforests, including three gecko genera, plus frogs, snakes, agamid lizards and squirrels. It has been hypothesized that repeated evolution of gliding is related to the dominance of Asian rainforest tree floras by dipterocarps. For dipterocarps to have influenced the evolution of gliding in Southeast Asian vertebrates, gliding lineages must have Eocene or later origins. However, divergence times are not known for most lineages. To investigate the temporal pattern of Asian gliding vertebrate evolution, we performed phylogenetic and molecular clock analyses. New sequence data for geckos incorporate exemplars of each gliding genus (Cosymbotus, Luperosaurus and Ptychozoon), whereas analyses of other vertebrate lineages use existing sequence data. Stem ages of most gliding vertebrates, including all geckos, cluster in the time period when dipterocarps came to dominate Asian tropical forests. These results demonstrate that a gliding/dipterocarp correlation is temporally viable, and caution against the assumption of early origins for apomorphic taxa.

  3. Gecko-Inspired Electrospun Flexible Fiber Arrays for Adhesion

    Science.gov (United States)

    Najem, Johnny F.

    The ability of geckos to adhere to vertical solid surfaces comes from their remarkable feet with millions of projections terminating in nanometer spatulae. We present a simple yet robust method for fabricating directionally sensitive dry adhesives. By using electrospun nylon 6 nanofiber arrays, we create gecko-inspired dry adhesives, that are electrically insulating, and that show shear adhesion strength of 27 N/cm2 on a glass slide. This measured value is 270% that reported of gecko feet and 97-fold above normal adhesion strength of the same arrays. The data indicate a strong shear binding-on and easy normal lifting-off. This anisotropic strength distribution is attributed to an enhanced shear adhesion strength with decreasing fiber diameter (d) and an optimum performance of nanofiber arrays in the shear direction over a specific range of thicknesses. With use of electrospinning, we report the fabrication of nylon 6 nanofiber arrays that show a friction coefficient (mu) of 11.5. These arrays possess significant shear adhesion strength and low normal adhesion strength. Increasing the applied normal load considerably enhances the shear adhesion strength and mu, irrespective of d and fiber arrays thickness (T). Fiber bending stiffness and fiber surface roughness are considerably decreased with diminishing d while fiber packing density is noticeably increased. These enhancements are proposed to considerably upsurge the shear adhesion strength between nanofiber arrays and a glass slide. The latter upsurge is mainly attributed to a sizeable proliferation in van der Waals (vdW) forces. These nanofiber arrays can be alternatively bound-on and lifted-off over a glass slide with a trivial decrease in the initial mu and adhesion strength. By using selective coating technique, we have also created hierarchical structures having closely packed nanofibers with d of 50 nm. We determine the effects of applied normal load, fiber surface roughness, loading angle, d, T, and repeated

  4. Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination.

    Science.gov (United States)

    Pokorná, Martina; Rábová, Marie; Ráb, Petr; Ferguson-Smith, Malcolm A; Rens, Willem; Kratochvíl, Lukáš

    2010-11-01

    The eyelid geckos (family Eublepharidae) include both species with temperature-dependent sex determination and species where genotypic sex determination (GSD) was suggested based on the observation of equal sex ratios at several incubation temperatures. In this study, we present data on karyotypes and chromosomal characteristics in 12 species (Aeluroscalabotes felinus, Coleonyx brevis, Coleonyx elegans, Coleonyx variegatus, Eublepharis angramainyu, Eublepharis macularius, Goniurosaurus araneus, Goniurosaurus lichtenfelderi, Goniurosaurus luii, Goniurosaurus splendens, Hemitheconyx caudicinctus, and Holodactylus africanus) covering all genera of the family, and search for the presence of heteromorphic sex chromosomes. Phylogenetic mapping of chromosomal changes showed a long evolutionary stasis of karyotypes with all acrocentric chromosomes followed by numerous chromosomal rearrangements in the ancestors of two lineages. We have found heteromorphic sex chromosomes in only one species, which suggests that sex chromosomes in most GSD species of the eyelid geckos are not morphologically differentiated. The sexual difference in karyotype was detected only in C. elegans which has a multiple sex chromosome system (X(1)X(2)Y). The metacentric Y chromosome evolved most likely via centric fusion of two acrocentric chromosomes involving loss of interstitial telomeric sequences. We conclude that the eyelid geckos exhibit diversity in sex determination ranging from the absence of any sexual differences to heteromorphic sex chromosomes, which makes them an interesting system for exploring the evolutionary origin of sexually dimorphic genomes.

  5. The embryology of the retinal pigmented epithelium in dwarf geckos (Gekkota: Sphaerodactylinae): a unique developmental pattern.

    Science.gov (United States)

    Guerra-Fuentes, Ricardo A; Daza, Juan D; Bauer, Aaron M

    2014-06-30

    The retinal pigmented epithelium (RPE) is a rounded shaped structure in almost all lizards. In the New World dwarf geckos, this structure shows an unusual morphology. In addition to this ocular character, we describe notable differences in the development of these geckos in comparison with available developmental staging tables for other geckos and squamate reptiles. We identified two main patterns of development of the RPE for squamates. These patterns were mapped onto a metatree of concordant hypotheses of squamates based on molecular data. During post-ovopositional stages the representative species of sphaerodactyls exhibit a RPE layer that transforms gradually from an ovoid form into the generalized spherical form. Sphaerodactyls are the only group of squamates in which this pattern is known. This transition might be circumstantial evidence that the accessory RPE plays a role in providing additional protection for their apomorphic concaviclivate temporal fovea. We also report the presence of conjunctival papillae in a developmental stage prior to the formation of scleral ossicles. This developmental progression is similar to that of birds and turtles.

  6. Neural basis of attachment-caregiving systems interaction:insights from neuroimaging

    Directory of Open Access Journals (Sweden)

    Delia eLenzi

    2015-08-01

    Full Text Available The attachment and the caregiving system are complementary systems which are active simultaneously in infant and mother interactions. This ensures the infant survival and optimal social, emotional and cognitive development. In this brief review we first define the characteristics of these two behavioral systems and the theory that links them, according to what Bowlby called the attachment-caregiving social bond (Bowlby, 1969. We then follow with those neuroimaging studies that have focused on this particular issue, i.e. those which have studied the activation of the careging system in women (using infant stimuli and have explored how the individual attachment model (through the Adult Attachment Interview modulates its activity. Studies report altered activation in limbic and prefrontal areas and in basal ganglia and hypothalamus/pituitary regions. These altered activations are thought to be the neural substrate of the attachment-caregiving systems interaction.

  7. Mechanisms of spectral tuning in the RH2 pigments of Tokay gecko and American chameleon

    Science.gov (United States)

    Takenaka, Naomi; Yokoyama, Shozo

    2009-01-01

    At present, molecular bases of spectral tuning in rhodopsin-like (RH2) pigments are not well understood. Here, we have constructed the RH2 pigments of nocturnal Tokay gecko (Gekko gekko) and diurnal American chameleon (Anolis carolinensis) as well as chimeras between them. The RH2 pigments of the gecko and chameleon reconstituted with 11-cis-retinal had the wavelengths of maximal absorption (λmax’s) of 467 and 496 nm, respectively. Chimeric pigment analyses indicated that 76–86%, 14–24%, and 10% of the spectral difference between them could be explained by amino acid differences in transmembrane (TM) helices I~IV, V~VII, and amino acid interactions between the two segments, respectively. Evolutionary and mutagenesis analyses revealed that the λmax’s of the gecko and chameleon pigments diverged from each other not only by S49A (serine to alanine replacement at residue 49), S49F (serine to phenylalanine), L52M (leucine to methionine), D83N (aspartic acid to asparagine), M86T (methionine to thereonine), and T97A (threonine to alanine) but also by other amino acid replacements that cause minor λmax-shifts individually. PMID:17590287

  8. Mechanisms of spectral tuning in the RH2 pigments of Tokay gecko and American chameleon.

    Science.gov (United States)

    Takenaka, Naomi; Yokoyama, Shozo

    2007-09-01

    At present, molecular bases of spectral tuning in rhodopsin-like (RH2) pigments are not well understood. Here, we have constructed the RH2 pigments of nocturnal Tokay gecko (Gekko gekko) and diurnal American chameleon (Anolis carolinensis) as well as chimeras between them. The RH2 pigments of the gecko and chameleon reconstituted with 11-cis-retinal had the wavelengths of maximal absorption (lambda(max)'s) of 467 and 496 nm, respectively. Chimeric pigment analyses indicated that 76-86%, 14-24%, and 10% of the spectral difference between them could be explained by amino acid differences in transmembrane (TM) helices I-IV, V-VII, and amino acid interactions between the two segments, respectively. Evolutionary and mutagenesis analyses revealed that the lambda(max)'s of the gecko and chameleon pigments diverged from each other not only by S49A (serine to alanine replacement at residue 49), S49F (serine to phenylalanine), L52M (leucine to methionine), D83N (aspartic acid to asparagine), M86T (methionine to threonine), and T97A (threonine to alanine) but also by other amino acid replacements that cause minor lambda(max)-shifts individually.

  9. Belt attachment and system

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Abraham D.; Davidson, Erick M.

    2018-03-06

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  10. Contaminant adhesion (aerial/ground biofouling) on the skin of a gecko.

    Science.gov (United States)

    Watson, Gregory S; Cribb, Bronwen W; Schwarzkopf, Lin; Watson, Jolanta A

    2015-07-06

    In this study, we have investigated the micro- and nano-structuring and contaminant adhesional forces of the outer skin layer of the ground dwelling gecko--Lucasium steindachneri. The lizard's skin displayed a high density of hairs with lengths up to 4 μm which were spherically capped with a radius of curvature typically less than 30 nm. The adhesion of artificial hydrophilic (silica) and hydrophobic (C18) spherical particles and natural pollen grains were measured by atomic force microscopy and demonstrated extremely low values comparable to those recorded on superhydrophobic insects. The lizard scales which exhibited a three-tier hierarchical architecture demonstrated higher adhesion than the trough regions between scales. The two-tier roughness of the troughs comprising folding of the skin (wrinkling) limits the number of contacting hairs with particles of the dimensions used in our study. The gecko skin architecture on both the dorsal and trough regions demonstrates an optimized topography for minimizing solid-solid and solid-liquid particle contact area, as well as facilitating a variety of particulate removal mechanisms including water-assisted processes. These contrasting skin topographies may also be optimized for other functions such as increased structural integrity, levels of wear protection and flexibility of skin for movement and growth. While single hair adhesion is low, contributions of many thousands of individual hairs (especially on the abdominal scale surface and if deformation occurs) may potentially aid in providing additional adhesional capabilities (sticking ability) for some gecko species when interacting with environmental substrates such as rocks, foliage and even man-made structuring. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  11. Ecological associations of autopodial osteology in Neotropical geckos.

    Science.gov (United States)

    Rothier, Priscila S; Brandt, Renata; Kohlsdorf, Tiana

    2017-03-01

    Coevolution of form and function inspires investigation of associations between morphological variation and the exploitation of specific ecological settings. Such relationships, based mostly on traits of external morphology, have been extensively described for vertebrates, and especially so for squamates. External features are, however, composed by both soft tissues and bones, and these likely play different biomechanical roles during locomotion, such as in the autopodia. Therefore, ecological trends identified on the basis of external morphological measurements may not be directly correlated with equivalent variation in osteology. Here, we investigate how refined parameters of autopodial osteology relate to ecology, by contrasting climbing and nonclimbing geckos. Our first step consisted of inferring how external and osteological morphometric traits coevolved in the group. Our results corroborate the hypothesis of coevolution between external and osteological elements in the autopodia of geckos, and provides evidence for associations between specific osteological traits and preferred locomotor habit. Specifically, nonclimbers exhibit longer ultimate and penultimate phalanges of Digit V in the manus and pes and also a longer fifth metatarsal in comparison with climbers, a pattern discussed here in the context of the differential demands made upon locomotion in specific ecological contexts. Our study highlights the relevance of osteological information for discussing the evolution of ecological associations of the tetrapod autopodium. J. Morphol. 278:290-299, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  12. Effects of spatial subsidies and habitat structure on the foraging ecology and size of geckos.

    Directory of Open Access Journals (Sweden)

    Amy A Briggs

    Full Text Available While it is well established that ecosystem subsidies--the addition of energy, nutrients, or materials across ecosystem boundaries--can affect consumer abundance, there is less information available on how subsidy levels may affect consumer diet, body condition, trophic position, and resource partitioning among consumer species. There is also little information on whether changes in vegetation structure commonly associated with spatial variation in subsidies may play an important role in driving consumer responses to subsidies. To address these knowledge gaps, we studied changes in abundance, diet, trophic position, size, and body condition of two congeneric gecko species (Lepidodactylus spp. that coexist in palm dominated and native (hereafter dicot dominated forests across the Central Pacific. These forests differ strongly both in the amount of marine subsidies that they receive from seabird guano and carcasses, and in the physical structure of the habitat. Contrary to other studies, we found that subsidy level had no impact on the abundance of either gecko species; it also did not have any apparent effects on resource partitioning between species. However, it did affect body size, dietary composition, and trophic position of both species. Geckos in subsidized, dicot forests were larger, had higher body condition and more diverse diets, and occupied a much higher trophic position than geckos found in palm dominated, low subsidy level forests. Both direct variation in subsidy levels and associated changes in habitat structure appear to play a role in driving these responses. These results suggest that variation in subsidy levels may drive important behavioral responses in predators, even when their numerical response is limited. Strong changes in trophic position of consumers also suggest that subsidies may drive increasingly complex food webs, with longer overall food chain length.

  13. Effects of spatial subsidies and habitat structure on the foraging ecology and size of geckos

    Science.gov (United States)

    Briggs, Amy A.; Young, Hillary S.; McCauley, Douglas J.; Hathaway, Stacie A.; Dirzo, Rodolfo; Fisher, Robert N.

    2012-01-01

    While it is well established that ecosystem subsidies—the addition of energy, nutrients, or materials across ecosystem boundaries—can affect consumer abundance, there is less information available on how subsidy levels may affect consumer diet, body condition, trophic position, and resource partitioning among consumer species. There is also little information on whether changes in vegetation structure commonly associated with spatial variation in subsidies may play an important role in driving consumer responses to subsidies. To address these knowledge gaps, we studied changes in abundance, diet, trophic position, size, and body condition of two congeneric gecko species (Lepidodactylus spp.) that coexist in palm dominated and native (hereafter dicot dominated) forests across the Central Pacific. These forests differ trongly both in the amount of marine subsidies that they receive from seabird guano and carcasses, and in the physical structure of the habitat. Contrary to other studies, we found that subsidy level had no impact on the abundance of either gecko species; it also did not have any apparent effects on resource partitioning between species. However, it did affect body size, dietary composition, and trophic position of both species. Geckos in subsidized, dicot forests were larger, had higher body condition and more diverse diets, and occupied a much higher trophic position than geckos found in palm dominated, low subsidy level forests. Both direct variation in subsidy levels and associated changes in habitat structure appear to play a role in driving these responses. These results suggest that variation in subsidy levels may drive important behavioral responses in predators, even when their numerical response is limited. Strong changes in trophic position of consumers also suggest that subsidies may drive increasingly complex food webs, with longer overall food chain length.

  14. All in the family: integrating attachment and family systems theories.

    Science.gov (United States)

    Crittenden, Patricia McKinsey; Dallos, Rudi

    2009-07-01

    This article brings together ideas from attachment and systemic family therapy. There is both growing interest among systemic practitioners in the conceptual and empirical base of attachment theory and also the need for attachment theory to expand dyadic patterning to include its context in family functioning. We propose the Dynamic-Maturational Model (DMM) as being the most compatible and useful variant of attachment theory. With its emphasis on the functional nature of behavior, a dynamic view of development and change, and a focus on multiple attachments and representational systems, the DMM fits systemic concepts well. We propose that many apparent discrepancies between the theories will disappear if careful distinctions are made between observed behavior, functional explanations, and attributions. We conclude with theory-based recommendations for selecting treatment strategies. Several case examples that are theory based, counterintuitive, and tied to disorders that are difficult to treat are offered to give substance to our ideas.

  15. A new species of Spauligodon (Nematoda: Oxyurida: Pharyngodonidae) in geckos from São Nicolau Island (Cape Verde) and its phylogenetic assessment.

    Science.gov (United States)

    Jorge, Fátima; Carretero, Miguel A; Perera, Ana; Harris, D James; Roca, Vicente

    2012-02-01

    A new nematode species, Spauligodon nicolauensis n. sp., is described from geckos Tarentola bocagei and Tarentola nicolauensis on the island of São Nicolau, Cape Verde. The new nematode was found in the pellets obtained directly from the geckos in a non-invasive fashion, and its identity was assessed both at morphologic and genetic levels. The new species has morphological similarities with Spauligodon tarentolae Spaul, 1926, also parasitizing geckos from the Canary Islands. However, the male cloacal region in the new species is distinct, presenting a different shape of the caudal papillae. The overall resemblance probably resulted from colonization via descent from an ancestor of S. tarentolae carried by the ancestor of Cape Verde Tarentola. The analysis of nuclear DNA sequences confirms that the new species is phylogenetically distinct from all other Spauligodon species already analyzed, forming a group clearly separated from species parasitizing lacertid lizards. The COI genetic distance suggests that the S. nicolauensis n. sp. found in the 2 species of geckos in São Nicolau Island may have resulted from a host-switching event, when they came into contact after the unification of the island.

  16. High Quality Bioreplication of Intricate Nanostructures from a Fragile Gecko Skin Surface with Bactericidal Properties

    Science.gov (United States)

    Green, David William; Lee, Kenneth Ka-Ho; Watson, Jolanta Anna; Kim, Hyun-Yi; Yoon, Kyung-Sik; Kim, Eun-Jung; Lee, Jong-Min; Watson, Gregory Shaun; Jung, Han-Sung

    2017-01-01

    The external epithelial surfaces of plants and animals are frequently carpeted with small micro- and nanostructures, which broadens their adaptive capabilities in challenging physical habitats. Hairs and other shaped protuberances manage with excessive water, light contaminants, predators or parasites in innovative ways. We are interested in transferring these intricate architectures onto biomedical devices and daily-life surfaces. Such a project requires a very rapid and accurate small-scale fabrication process not involving lithography. In this study, we describe a simple benchtop biotemplating method using shed gecko lizard skin that generates duplicates that closely replicate the small nanotipped hairs (spinules) that cover the original skin. Synthetic replication of the spinule arrays in popular biomaterials closely matched the natural spinules in length. More significantly, the shape, curvature and nanotips of the synthetic arrays are virtually identical to the natural ones. Despite some small differences, the synthetic gecko skin surface resisted wetting and bacterial contamination at the same level as natural shed skin templates. Such synthetic gecko skin surfaces are excellent platforms to test for bacterial control in clinical settings. We envision testing the biocidal properties of the well-matched templates for fungal spores and viral resistance in biomedicine as well as co/multi-cultures.

  17. Expression of beta-keratin mRNAs and proline uptake in epidermal cells of growing scales and pad lamellae of gecko lizards

    Science.gov (United States)

    Alibardi, Lorenzo; Toni, Mattia; Valle, Luisa Dalla

    2007-01-01

    Beta-keratins form a large part of the proteins contained in the hard beta layer of reptilian scales. The expression of genes encoding glycine–proline-rich beta-keratins in normal and regenerating epidermis of two species of gecko lizards has been studied by in situ hybridization. The probes localize mRNAs in differentiating oberhautchen and beta cells of growing scales and in modified scales, termed pad lamellae, on the digits of gecko lizards. In situ localization at the ultrastructural level shows clusters of gold particles in the cytoplasm among beta-keratin filaments of oberhautchen and beta cells. They are also present in the differentiating elongation or setae of oberhautchen cells present in pad lamellae. Setae allow geckos to adhere and climb vertical surfaces. Oberhautchen and beta cells also incorporate tritiated proline. The fine localization of the beta-keratin mRNAs and the uptake of proline confirms the biomolecular data that identified glycine–proline-rich beta-keratin in differentiating beta cells of gecko epidermis. The present study also shows the presence of differentiating and metabolically active cells in both inner and outer oberhautchen/beta cells at the base of the outer setae localized at the tip of pad lamellae. The addition of new beta and alpha cells to the corneous layer near the tip of the outer setae explains the anterior movement of the setae along the apical free-margin of pad lamellae. The rapid replacement of setae ensures the continuous usage of the gecko's adhesive devices, the pad lamellae, during most of their active life. PMID:17553098

  18. The network perspective: an integration of attachment and family systems theories.

    Science.gov (United States)

    Kozlowska, Kasia; Hanney, Lesley

    2002-01-01

    In this article we discuss the network paradigm as a useful base from which to integrate attachment and family systems theories. The network perspective refers to the application of general systems theory to living systems, and provides a framework that conceptualizes the dyadic and family systems as simultaneously distinct and interconnected. Network thinking requires that the clinician holds multiple perspectives in mind, considers each system level as both a part and a whole, and shifts the focus of attention between levels as required. Key epistemological issues that have hindered the integration of the theories are discussed. These include inconsistencies within attachment theory itself and confusion surrounding the theoretical conceptualizations of the relationship between attachment and family systems theories. Detailed information about attachment categories is provided using the Dynamic Maturational model. Case vignettes illustrating work with young children and their families explore the clinical implications of integrating attachment data into family therapy practice.

  19. Organization of the auditory brainstem in a lizard, Gekko gecko. I. Auditory nerve, cochlear nuclei, and superior olivary nuclei

    DEFF Research Database (Denmark)

    Tang, Y. Z.; Christensen-Dalsgaard, J.; Carr, C. E.

    2012-01-01

    We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko (Gekko gecko). The auditory nerve has two divisions, a rostroventrally directed projection of mid- to high best-frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of lo...... of auditory connections in lizards and archosaurs but also different processing of low- and high-frequency information in the brainstem. J. Comp. Neurol. 520:17841799, 2012. (C) 2011 Wiley Periodicals, Inc...

  20. Breeding of a leopard gecko in a kindergarden and it's utilization for awakening and intensifying children's interest in nature

    OpenAIRE

    Kovalová, Marie

    2016-01-01

    This thesis is focused on the theme of the reciprocal action of animals and pre-school children. It introduces us to the breeding of leopard geckos in kindergartens (with its benefits and disadvantages). Based on case studies, it describes a leopard gecko's influence on preschool children's personalities in kindergarten. The main method of research involves observing individual children as well as a group of children in a one- room kindergarten, Lísteček. Kindergarten Lísteček enrolls childre...

  1. Development of an attached microalgal growth system for biofuel production.

    Science.gov (United States)

    Johnson, Michael B; Wen, Zhiyou

    2010-01-01

    Algal biofuel production has gained a renewed interest in recent years but is still not economically feasible due to several limitations related to algal culture. The objective of this study is to explore a novel attached culture system for growing the alga Chlorella sp. as biodiesel feedstock, with dairy manure wastewater being used as growth medium. Among supporting materials tested for algal attachment, polystyrene foam led to a firm attachment, high biomass yield (25.65 g/m(2), dry basis), and high fatty acid yield (2.31 g/m(2)). The biomass attached on the supporting material surface was harvested by scraping; the residual colonies left on the surface served as inoculum for regrowth. The algae regrowth on the colony-established surface resulted in a higher biomass yield than that from the initial growth on fresh surface due to the downtime saved for initial algal attachment. The 10-day regrowth culture resulted in a high biodiesel production potential with a fatty acid methyl esters yield of 2.59 g/m(2) and a productivity of 0.26 g/m(-2) day(-1). The attached algal culture also removed 61-79% total nitrogen and 62-93% total phosphorus from dairy manure wastewater, depending on different culture conditions. The biomass harvested from the attached growth system (through scraping) had a water content of 93.75%, similar to that harvested from suspended culture system (through centrifugation). Collectively, the attached algal culture system with polystyrene foam as a supporting material demonstrated a good performance in terms of biomass yield, biodiesel production potential, ease to harvest biomass, and physical robustness for reuse.

  2. Quantification of three steroid hormone receptors of the leopard gecko (Eublepharis macularius), a lizard with temperature-dependent sex determination: their tissue distributions and the effect of environmental change on their expressions.

    Science.gov (United States)

    Endo, Daisuke; Park, Min Kyun

    2003-12-01

    Sex steroid hormones play a central role in the reproduction of all vertebrates. These hormones function through their specific receptors, so the expression levels of the receptors may reflect the responsibility of target organs. However, there was no effective method to quantify the expression levels of these receptors in reptilian species. In this study, we established the competitive-PCR assay systems for the quantification of the mRNA expression levels of three sex steroid hormone receptors in the leopard gecko. These assay systems were successfully able to detect the mRNA expression level of each receptor in various organs of male adult leopard geckoes. The expression levels of mRNA of these receptors were highly various depending on the organs assayed. This is the first report regarding the tissue distributions of sex steroid hormone receptor expressions in reptile. The effects of environmental conditions on these hormone receptor expressions were also examined. After the low temperature and short photoperiod treatment for 6 weeks, only the androgen receptor expression was significantly increased in the testes. The competitive-PCR assay systems established in this report should be applicable for various studies of the molecular mechanism underlying the reproductive activity of the leopard gecko.

  3. Lateral movements of a massive tail influence gecko locomotion: an integrative study comparing tail restriction and autotomy

    OpenAIRE

    Jagnandan, Kevin; Higham, Timothy E.

    2017-01-01

    Tails are an intricate component of the locomotor system for many vertebrates. Leopard geckos (Eublepharis macularius) possess a large tail that is laterally undulated during steady locomotion. However, the tail is readily shed via autotomy, resulting in the loss of tail function, loss in body mass, and a cranial shift in the center of mass. To elucidate the function of tail undulations, we investigated changes in limb kinematics after manipulating the tail artificially by restricting tail un...

  4. Chlorine stress mediates microbial surface attachment in drinking water systems.

    Science.gov (United States)

    Liu, Li; Le, Yang; Jin, Juliang; Zhou, Yuliang; Chen, Guowei

    2015-03-01

    Microbial attachment to drinking water pipe surfaces facilitates pathogen survival and deteriorates disinfection performance, directly threatening the safety of drinking water. Notwithstanding that the formation of biofilm has been studied for decades, the underlying mechanisms for the origins of microbial surface attachment in biofilm development in drinking water pipelines remain largely elusive. We combined experimental and mathematical methods to investigate the role of environmental stress-mediated cell motility on microbial surface attachment in chlorination-stressed drinking water distribution systems. Results show that at low levels of disinfectant (0.0-1.0 mg/L), the presence of chlorine promotes initiation of microbial surface attachment, while higher amounts of disinfectant (>1.0 mg/L) inhibit microbial attachment. The proposed mathematical model further demonstrates that chlorination stress (0.0-5.0 mg/L)-mediated microbial cell motility regulates the frequency of cell-wall collision and thereby controls initial microbial surface attachment. The results reveal that transport processes and decay patterns of chlorine in drinking water pipelines regulate microbial cell motility and, thus, control initial surface cell attachment. It provides a mechanistic understanding of microbial attachment shaped by environmental disinfection stress and leads to new insights into microbial safety protocols in water distribution systems.

  5. Identification and characterization of a reptilian GnRH receptor from the leopard gecko.

    Science.gov (United States)

    Ikemoto, T; Enomoto, M; Park, M K

    2004-02-12

    Gonadotropin-releasing hormone (GnRH) plays a pivotal role in the regulation of reproductive functions through interactions with its specific receptor. We describe the first molecular cloning and characterization of a full-length GnRH receptor (GnRHR) from the leopard gecko Eublepharis macularius. It has a distinct genomic structure consisting of five exons and four introns, compared with all the other reported GnRHR genes. A native GnRH form, cGnRH-II, stimulated inositol phosphate (IP) production in COS-7 cells transiently transfected with the GnRHR, in a dose dependent manner. The mRNA was expressed in all the tissues and organs examined. Molecular phylogenetic analysis revealed that the cloned GnRHR belongs to the type 2/nonmammalian I GnRHR. Low-expression levels were observed from the pituitary glands of reproductively active leopard geckos, indicating the possibility that there is at least one more type of GnRHR highly expressed in the pituitary gland for the gonadotropin secretion in this reptile.

  6. Sex determination in Madagascar geckos of the genus Paroedura (Squamata: Gekkonidae): are differentiated sex chromosomes indeed so evolutionary stable?

    Science.gov (United States)

    Koubová, Martina; Johnson Pokorná, Martina; Rovatsos, Michail; Farkačová, Klára; Altmanová, Marie; Kratochvíl, Lukáš

    2014-12-01

    Among amniote vertebrates, geckos represent a clade with exceptional variability in sex determination; however, only a minority of species of this highly diverse group has been studied in this respect. Here, we describe for the first time a female heterogamety in the genus Paroedura, the group radiated in Madagascar and adjacent islands. We identified homomorphic ZZ/ZW sex chromosomes with a highly heterochromatic W chromosome in Paroedura masobe, Paroedura oviceps, Paroedura karstophila, Paroedura stumpffi, and Paroedura lohatsara. Comparative genomic hybridization (CGH) revealed that female-specific sequences are greatly amplified in the W chromosome of P. lohatsara and that P. gracilis seems to possess a derived system of multiple sex chromosomes. Contrastingly, neither CGH nor heterochromatin visualization revealed differentiated sex chromosomes in the members of the Paroedura picta-Paroedura bastardi-Paroedura ibityensis clade, which is phylogenetically nested within lineages with a heterochromatic W chromosome. As a sex ratio consistent with genotypic sex determination has been reported in P. picta, it appears that the members of the P. picta-P. bastardi-P. ibityensis clade possess homomorphic, poorly differentiated sex chromosomes and may represent a rare example of evolutionary loss of highly differentiated sex chromosomes. Fluorescent in situ hybridization (FISH) with a telomeric probe revealed a telomere-typical pattern in all species and an accumulation of telomeric sequences in the centromeric region of autosomes in P. stumpffi and P. bastardi. Our study adds important information for the greater understanding of the variability and evolution of sex determination in geckos and demonstrates how the geckos of the genus Paroedura provide an interesting model for studying the evolution of the sex chromosomes.

  7. Synchronization of spontaneous otoacoustic emissions in the tokay gecko

    Science.gov (United States)

    Roongthumskul, Yuttana; Hudspeth, A. J.

    2018-05-01

    Spontaneous otoacoustic emissions (SOAEs) are a universal feature of all classes of tetrapods. Although the generation mechanism of SOAEs are incompletely understood, these emissions are undoubtedly associated with the active process of the inner ear. In most lizards, unlike mammals and amphibians, robust SOAEs can ordinarily be detected from both ears. In this work, we investigated the interactions between emissions recorded simultaneously from the two ears of tokay geckos. We found that the frequency spectra of SOAEs from both ears of an individual animal are partially correlated: the peaks of several emissions occur at identical frequencies. To investigate the underlying mechanisms of these identical-frequency SOAEs, we perturbed the emissions from one or both ears by manipulating the pressure in the ear canals or by decreasing the local temperature in the vicinity of one inner ear. Suppression of SOAEs due to large positive pressures revealed that some identical-frequency emissions were generated unilaterally, whereas others were contributed by both ears at identical or slightly different frequencies. These bilaterally generated SOAEs became desynchronized as their frequency detuning grew sufficiently large, a phenomenon consistent with the synchronization of two active oscillators. Finally, we found that manipulations of the volume of the oral cavity or altering the impedance of the tympanum strongly affected the synchronization of SOAEs. These findings agreed with previous studies suggesting that the tokay gecko, like other lizards, exhibits strong acoustic coupling between its tympani through the oral cavity.

  8. Cryptic diversity and population genetic structure in the rare, endemic, forest-obligate, slender geckos of the Philippines.

    Science.gov (United States)

    Siler, Cameron D; Dececchi, T Alex; Merkord, Chris L; Davis, Drew R; Christiani, Tony J; Brown, Rafe M

    2014-01-01

    Recent studies of forest lizards in Southeast Asia have highlighted spectacular morphological and cryptic genetic diversity in several poorly known clades. Unfortunately, many of the included species have microhabitat preferences for forested environments, and therefore they are threatened by extensive forest destruction throughout the region. This is particularly true in the Philippines, an archipelago with a strikingly high proportion (84%) of endemic geckos. Abundances inferred from historical museum collections suggests that we are in a critical period where apparent declines in population viability and species' abundance have taken place faster than the growth in our understanding of alpha diversity. This phenomenon is exemplified in the exceedingly rare Philippine slender forest geckos of the genus Pseudogekko. Most of the known species are rarely encountered by field biologists, and species boundaries are unclear; this poor state of knowledge impedes effective conservation measures. Using the first multilocus phylogeny for these taxa, and phylogenetic and population genetic approaches, we elucidate evolutionary lineages and delimit species-level conservation targets in this unique radiation of endemic Philippine geckos. The results support the presence of widespread cryptic diversity in the genus, providing a framework for the re-evaluation of conservation priorities aimed at protecting these rare, forest-obligate species. Copyright © 2013 Elsevier Inc. All rights reserved.

  9. Adhesive behaviour of gecko-inspired nanofibrillar arrays: combination of experiments and finite element modelling

    International Nuclear Information System (INIS)

    Wang Zhengzhi; Xu Yun; Gu Ping

    2012-01-01

    A polypropylene nanofibrillar array was successfully fabricated by template-assisted nanofabrication strategy. Adhesion properties of this gecko-inspired structure were studied through two parallel and independent approaches: experiments and finite element simulations. Experimental results show relatively good normal adhesion, but accompanied by high preloads. The interfacial adhesion was modelled by effective spring elements with piecewise-linear constitution. The effective elasticity of the fibre-array system was originally calculated from our measured elasticity of single nanowire. Comparisons of the experimental and simulative results reveal quantitative agreement except for some explainable deviations, which suggests the potential applicability of the present models and applied theories. (fast track communication)

  10. Phylogeography and dispersal in the velvet gecko (Oedura lesueurii, and potential implications for conservation of an endangered snake (Hoplocephalus bungaroides

    Directory of Open Access Journals (Sweden)

    Dubey Sylvain

    2012-05-01

    Full Text Available Abstract Background To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides, which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velvet geckos, to clarify the lizards’ phylogeographic history and landscape genetics. We also analysed 260 records from a longterm (3-year capture-mark-recapture program at three sites, to evaluate dispersal rates of geckos as a function of locality, sex and body size. Results The genetic analyses revealed three ancient lineages in the north, south and centre of the species’ current range. Estimates of gene flow suggest low dispersal rates, constrained by the availability of contiguous rocky habitat. Mark-recapture records confirm that these lizards are highly sedentary, with most animals moving  Conclusion The low vagility of these lizards suggests that they will be slow to colonise vacant habitat patches; and hence, efforts to restore degraded habitats for broad-headed snakes may need to include translocation of lizards.

  11. Sexual dimorphism in head size of the Mediterranean gecko Hemidactylus turcicus (Sauria: Gekkonidae)

    Science.gov (United States)

    Daniel Saenz; Richard N. Conner

    1996-01-01

    Comparisons were made between 53 female and 67 male Mediterranean geckos (Hemidactylus turcicus) collected from the campus of Stephen F. Austin State University in Nacogdoches, Texas. Head dimensions (length, depth and width) and weight of adult males and females were compared with analysis of covariance using snout-vent-length as a covariate. Males were...

  12. Topological systems versus attachment relations | Guido ...

    African Journals Online (AJOL)

    The manuscript makes a category-theoretic comparison between the concepts of topological system of S. Vickers and attachment relation of C. Guido. With the help of the recent definition of the notions in the framework of an arbitrary variety of algebras, we consider functorial relationships between the categories of such ...

  13. Lateral movements of a massive tail influence gecko locomotion: an integrative study comparing tail restriction and autotomy.

    Science.gov (United States)

    Jagnandan, Kevin; Higham, Timothy E

    2017-09-07

    Tails are an intricate component of the locomotor system for many vertebrates. Leopard geckos (Eublepharis macularius) possess a large tail that is laterally undulated during steady locomotion. However, the tail is readily shed via autotomy, resulting in the loss of tail function, loss in body mass, and a cranial shift in the center of mass. To elucidate the function of tail undulations, we investigated changes in limb kinematics after manipulating the tail artificially by restricting tail undulations and naturally by removing the tail via autotomy. Restricting tail undulations resulted in kinematic adjustments similar to those that occur following tail autotomy, characterized by more flexed hind limb joints. These data suggest that effects of autotomy on locomotion may be linked to the loss of tail movements rather than the loss of mass or a shift in center of mass. We also provide empirical support for the link between lateral tail undulations and step length through the rotation of the pelvic girdle and retraction of the femur. Restriction and autotomy of the tail limits pelvic rotation, which reduces femur retraction and decreases step length. Our findings demonstrate a functional role for tail undulations in geckos, which likely applies to other terrestrial vertebrates.

  14. A preliminary phylogeny of the Palearctic naked-toed geckos (Reptilia: Squamata: Gekkonidae) with taxonomic implications.

    Science.gov (United States)

    Bauer, Aaron M; Masroor, Rafaqat; Titus-McQuillan, James; Heinicke, Matthew P; Daza, Juan D; Jackman, Todd R

    2013-01-08

    Palearctic naked-toed geckos are a group of gekkonid geckos that range from North Africa to northern India and western China, with their greatest diversity in Iran and Pakistan. Relationships among the constituent genera remain incompletely resolved and the monophyly of key genera remains unverified. Further, competing classifications are in current use and many species have been allocated to different genera by different authors. We used both mitochondrial (ND2) and nuclear genes (RAG1, PDC) to explore relationships among representatives of all but one genus in the group (Rhinogecko), including four genera not previously included in phylogenetic analyses (Asiocolotes, Altigekko, Indogekko, and Siwaligekko). Siwaligekko (and presumably other Tibeto-Himalayan species often referred to Cyrtopodion) are more closely related to tropical Asian Cyrtodactylus than to Palearctic naked-toed geckos. Sampled species of Asiocolotes and Altigekko are sister taxa, but both genera are here considered junior subjective synonyms of Altiphylax. Cyrtopodion sensu lato is non-monophyletic; Mediodactylus and Tenuidactylus, which have variably been considered as subgenera or synonyms of Cyrtopodion are both valid genera. Indogekko is embedded within Cyrtopodion and is here treated as a subgenus. Bunopus and Crossobamon are closely related to one-another, and with Agamura are interdigitated among taxa previously assigned to Cyrtopodion. Our data confirm the previous identification of a Saharo-Arabian Stenodactylus/Tropiocolotes/Pseudoceramodactylus clade and verify that Microgecko and Alsophylax are not members of the main clade of Palearctic naked-toed geckos. Osteological differences between Tropiocolotes and Microgecko, formerly treated as congeneric, are discussed and illustrated. The divergence between Cyrtodactylus and the Palearctic naked-toed clade predates the initial collision of the Indian and Eurasian plates, but deeper divergences within both groups are

  15. Phylogeny and cryptic diversification in Southeast Asian flying geckos.

    Science.gov (United States)

    Brown, Rafe M; Siler, Cameron D; Lee Grismer, L; Das, Indraneil; McGuire, Jimmy A

    2012-11-01

    The closed-canopy forests of Southeast Asia are home to an impressive number of vertebrates that have independently evolved morphologies that enhance directed aerial descent (gliding, parachuting). These assemblages include numerous mammal, frog, snake, and lizard clades. Several genera of gekkonid lizards, in particular, have evolved specialized structures such as cutaneous expansions, flaps, and midbody patagia, that enhance lift generation in the context of unique gliding and parachuting locomotion. The genus Ptychozoon represents arguably the most morphologically extreme, highly specialized clade of gliding geckos. Despite their notoriety and celebrated locomotor ability, members of the genus Ptychozoon have never been the subject of a species-level molecular phylogenetic analysis. In this paper, we utilize molecular sequence data from mitochondrial and nuclear gene fragments to estimate the evolutionary relationships of this unique group of flying geckos. Capitalizing on the recent availability of genetic samples for even the rarest of known species, we include the majority of known taxa and use model-based phylogenetic methods to reconstruct their evolutionary history. Because one species, P. kuhli, exhibits an unusually wide distribution coupled with an impressive range of morphological variation, we additionally use intensive phylogeographic/population genetic sampling, phylogenetic network analyses, and Bayesian species delimitation procedures to evaluate this taxon for the possible presence of cryptic evolutionary lineages. Our results suggest that P. kuhli may consist of between five and nine unrecognized, distinct species. Although we do not elevate these lineages to species status here, our findings suggest that lineage diversity in Ptychozoon is likely dramatically underestimated. Copyright © 2012 Elsevier Inc. All rights reserved.

  16. Morphometric and molecular characterization of Parapharyngodon echinatus (Nematoda, Pharyngodonidae) from the Senegal gecko ( Tarentola parvicarinata )

    Czech Academy of Sciences Publication Activity Database

    Mašová, Š.; Baruš, Vlastimil; Hodová, I.; Matějusová, I.; Koubek, Petr; Koubková, B.

    2008-01-01

    Roč. 53, č. 3 (2008), s. 274-283 ISSN 1230-2821 R&D Projects: GA AV ČR IAA6093404 Institutional research plan: CEZ:AV0Z60930519 Keywords : Nematoda * Senegal gecko * West Africa Subject RIV: EG - Zoology Impact factor: 0.748, year: 2008

  17. Vestibular cerebellum of thick-toed geckos (Chondrodactylus turnery GRAY, 1864) and C57/BL6N mice after the long-term space flight on the biosatellite BION-M1.

    Science.gov (United States)

    Alexandra, Proshchina; Anastasia, Kharlamova; Valeriy, Barabanov; Victoria, Gulimova; Sergey, Saveliev

    2017-01-01

    The aim of this study was to estimate the effects of long-term space flights on neuronal and glial cells of the vestibular cerebellum of C57/BL6N mice and thick-toed geckos (Chondrodactylus turnery GRAY, 1864). The cerebella from 26 mice and 13 geckos were used in this study. Ten mice and five geckos were flown aboard the BION-M1 biosatellite. The other animals were used as controls. We used immunohistochemical techniques and classical histological method to reveal cell types in the vestibular cerebellum. Nonspecific pathomorphological changes in the Purkinje cells (such as chromatolysis, vacuolization and hyperchromatosis) were observed in the flight groups. However, these changes are reversible and were also found in some neurons in the control groups. In addition, as the vestibular cerebellum is an evolutionarily stable structure, thick-toed geckos may be a useful model for space flight studies on the vertebrate cerebellum. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Vestibular nuclei characterized by calcium-binding protein immunoreactivity and tract tracing in Gekko gecko.

    Science.gov (United States)

    Song, Jing; Wang, Wenbo; Carr, Catherine E; Dai, Zhendong; Tang, Yezhong

    2013-02-01

    Immunohistochemical techniques were used to describe the distribution of the calcium binding proteins calretinin, calbindin and parvalbumin as well as synaptic vesicle protein 2 in the vestibular nuclei of the Tokay gecko (Gekko gecko). In addition, tract tracing was used to investigate connections between the vestibular nerves and brainstem nuclei. Seven vestibular nuclei were recognized: the nuclei cerebellaris lateralis (Cerl), vestibularis dorsolateralis (Vedl), ventrolateralis (Vevl), ventromedialis (Vevm), tangentialis (Vetg), ovalis (VeO) and descendens (Veds). Vestibular fibers entered the brainstem with the ascending branch projecting to Vedl and Cerl, the lateral descending branch to Veds, and the medial descending branch to ipsilateral Vevl. Cerl lay most rostral, in the cerebellar peduncle. Vedl, located rostrally, was ventral to the cerebellar peduncle, and consisted of loosely arranged multipolar and monopolar cells. Vevl was found at the level of the vestibular nerve root and contained conspicuously large cells and medium-sized cells. Veds is a large nucleus, the most rostral portion of which is situated lateral and ventral to Vevl, and occupies much of the dorsal brainstem extending caudally through the medulla. VeO is a spherically shaped cell group lateral to the auditory nucleus magnocellularis and dorsal to the caudal part of Vevl. Vevm and Vetg were small in the present study. Except for VeO, all other vestibular nuclei appear directly comparable to counterparts in other reptiles and birds based on their location, cytoarchitecture, and connections, indicating these are conserved features of the vestibular system. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Phylogeography and dispersal in the velvet gecko (Oedura lesueurii), and potential implications for conservation of an endangered snake (Hoplocephalus bungaroides)

    Science.gov (United States)

    2012-01-01

    Background To conserve critically endangered predators, we also need to conserve the prey species upon which they depend. Velvet geckos (Oedura lesueurii) are a primary prey for the endangered broad-headed snake (Hoplocephalus bungaroides), which is restricted to sandstone habitats in southeastern Australia. We sequenced the ND2 gene from 179 velvet geckos, to clarify the lizards’ phylogeographic history and landscape genetics. We also analysed 260 records from a longterm (3-year) capture-mark-recapture program at three sites, to evaluate dispersal rates of geckos as a function of locality, sex and body size. Results The genetic analyses revealed three ancient lineages in the north, south and centre of the species’ current range. Estimates of gene flow suggest low dispersal rates, constrained by the availability of contiguous rocky habitat. Mark-recapture records confirm that these lizards are highly sedentary, with most animals moving < 30 m from their original capture site even over multi-year periods. Conclusion The low vagility of these lizards suggests that they will be slow to colonise vacant habitat patches; and hence, efforts to restore degraded habitats for broad-headed snakes may need to include translocation of lizards. PMID:22583676

  20. Organization and activation of sexual and agonistic behavior in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Rhen, T; Crews, D

    2000-04-01

    Gonadal sex is determined by the temperature experienced during incubation in the leopard gecko (Eublepharis macularius). Furthermore, both factors, incubation temperature and gonadal sex, influence adult sexual and agonistic behavior in this species. Yet it is unclear whether such differences in behavior are irreversibly organized during development or are mediated by differences in hormone levels in adulthood. To address this question, we gonadectomized adult females and males generated from a female-biased (30 degrees C) and a male-biased (32.5 degrees C) incubation temperature and treated them with equivalent levels of various sex steroids. We found that 17beta-estradiol (E(2)) activated sexual receptivity in females but not males, suggesting an organized sex difference in behavioral sensitivity to E(2). There were also organized and activated sex differences in attractivity to stimulus males. Although females were more attractive than males when treated with E(2), both sexes were equally unattractive when treated with dihydrotestosterone (DHT) or testosterone (T). Likewise, sex differences in aggressive and submissive behavior were organized and activated. Attacks on stimulus males were activated by T in males but not in females. In contrast, hormones did not influence flight behavior in males but did affect female submissiveness. Overall, males also evoked more attacks by stimulus males than did females. Nevertheless, females and males treated with androgens evoked more attacks than animals of the same sex that were treated with cholesterol or E(2). Incubation temperature had some weak effects on certain behaviors and no effect on others. This suggests that temperature effects in gonadally intact geckos may be due primarily to differences in circulating levels of hormones in adulthood. We conclude that gonadal sex has both organizational and activational effects on various behaviors in the leopard gecko. Copyright 2000 S. Karger AG, Basel

  1. Scar-free cutaneous wound healing in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Peacock, Hanna M; Gilbert, Emily A B; Vickaryous, Matthew K

    2015-11-01

    Cutaneous wounds heal with two possible outcomes: scarification or near-perfect integumentary restoration. Whereas scar formation has been intensively investigated, less is known about the tissue-level events characterising wounds that spontaneously heal scar-free, particularly in non-foetal amniotes. Here, a spatiotemporal investigation of scar-free cutaneous wound healing following full-thickness excisional biopsies to the tail and body of leopard geckos (Eublepharis macularius) is provided. All injuries healed without scarring. Cutaneous repair involves the development of a cell-rich aggregate within the wound bed, similar to scarring wounds. Unlike scar formation, scar-free healing involves a more rapid closure of the wound epithelium, and a delay in blood vessel development and collagen deposition within the wound bed. It was found that, while granulation tissue of scarring wounds is hypervascular, scar-free wound healing conspicuously does not involve a period of exuberant blood vessel formation. In addition, during scar-free wound healing the newly formed blood vessels are typically perivascular cell-supported. Immunohistochemistry revealed widespread expression of both the pro-angiogenic factor vascular endothelial growth factor A and the anti-angiogenic factor thrombospondin-1 within the healing wound. It was found that scar-free wound healing is an intrinsic property of leopard gecko integument, and involves a modulation of the cutaneous scar repair program. This proportional revascularisation is an important factor in scar-free wound healing. © 2015 Anatomical Society.

  2. Flip, flop and fly: modulated motor control and highly variable movement patterns of autotomized gecko tails.

    Science.gov (United States)

    Higham, Timothy E; Russell, Anthony P

    2010-02-23

    Many animals lose and regenerate appendages, and tail autotomy in lizards is an extremely well-studied example of this. Whereas the energetic, ecological and functional ramifications of tail loss for many lizards have been extensively documented, little is known about the behaviour and neuromuscular control of the autotomized tail. We used electromyography and high-speed video to quantify the motor control and movement patterns of autotomized tails of leopard geckos (Eublepharis macularius). In addition to rhythmic swinging, we show that they exhibit extremely complex movement patterns for up to 30 min following autotomy, including acrobatic flips up to 3 cm in height. Unlike the output of most central pattern generators (CPGs), muscular control of the tail is variable and can be arrhythmic. We suggest that the gecko tail is well suited for studies involving CPGs, given that this spinal preparation is naturally occurring, requires no surgery and exhibits complex modulation.

  3. Characterization of TGFβ signaling during tail regeneration in the leopard Gecko (Eublepharis macularius).

    Science.gov (United States)

    Gilbert, Richard W D; Vickaryous, Matthew K; Viloria-Petit, Alicia M

    2013-07-01

    The transforming growth factor beta (TGFβ)/activin signaling pathway has a number of documented roles during wound healing and is increasingly appreciated as an essential component of multi-tissue regeneration that occurs in amphibians and fish. Among amniotes (reptiles and mammals), less is known due in part to the lack of an appropriate model organism capable of multi-tissue regeneration. The leopard gecko Eublepharis macularius is able to spontaneously, and repeatedly, regenerate its tail following tail loss. We examined the expression and localization of several key components of the TGFβ/activin signaling pathway during tail regeneration of the leopard gecko. We observed a marked increase in phosphorylated Smad2 expression within the regenerate blastema indicating active TGFβ/activin signaling. Interestingly, during early regeneration, TGFβ1 expression is limited whereas activin-βA is strongly upregulated. We also observe the expression of EMT transcription factors Snail1 and Snail2 in the blastema. Combined, these observations provide strong support for the importance of different TGFβ ligands during multi-tissue regeneration and the potential role of TGFβ/activin-induced EMT programs during this process. Copyright © 2013 Wiley Periodicals, Inc.

  4. Preliminary results on tail energetics in the Moorish gecko, Tarentola mauritanica.

    Directory of Open Access Journals (Sweden)

    marco zuffi

    2011-06-01

    Full Text Available The amount of lipids, proteins, ashes and water in original versus regenerated tails in Tarentola mauritanica shows differences, especially on the lipid fraction, supporting adaptive function hypotheses during reproduction of regenerated tails in geckos.

  5. Off the scale: a new species of fish-scale gecko (Squamata: Gekkonidae: Geckolepis with exceptionally large scales

    Directory of Open Access Journals (Sweden)

    Mark D. Scherz

    2017-02-01

    Full Text Available The gecko genus Geckolepis, endemic to Madagascar and the Comoro archipelago, is taxonomically challenging. One reason is its members ability to autotomize a large portion of their scales when grasped or touched, most likely to escape predation. Based on an integrative taxonomic approach including external morphology, morphometrics, genetics, pholidosis, and osteology, we here describe the first new species from this genus in 75 years: Geckolepis megalepis sp. nov. from the limestone karst of Ankarana in northern Madagascar. The new species has the largest known body scales of any gecko (both relatively and absolutely, which come off with exceptional ease. We provide a detailed description of the skeleton of the genus Geckolepis based on micro-Computed Tomography (micro-CT analysis of the new species, the holotype of G. maculata, the recently resurrected G. humbloti, and a specimen belonging to an operational taxonomic unit (OTU recently suggested to represent G. maculata. Geckolepis is characterized by highly mineralized, imbricated scales, paired frontals, and unfused subolfactory processes of the frontals, among other features. We identify diagnostic characters in the osteology of these geckos that help define our new species and show that the OTU assigned to G. maculata is probably not conspecific with it, leaving the taxonomic identity of this species unclear. We discuss possible reasons for the extremely enlarged scales of G. megalepis in the context of an anti-predator defence mechanism, and the future of Geckolepis taxonomy.

  6. First record of cannibalism in the Lima leaf-toed gecko, Phyllodactylus sentosus (Reptilia, Phyl-lodactylidae

    Directory of Open Access Journals (Sweden)

    Fernando Valdez

    2017-10-01

    Full Text Available We report a case of cannibalism for the Lima leaf-toed gecko, Phyllodactylus sentosus, in which an adult male devoured a juvenile. No reported cases were found in other species of the same genus, so we consider that this is the first report of cannibalism in Phyllodactylus.

  7. Attachment, self-esteem, worldviews, and terror management: evidence for a tripartite security system.

    Science.gov (United States)

    Hart, Joshua; Shaver, Phillip R; Goldenberg, Jamie L

    2005-06-01

    On the basis of prior work integrating attachment theory and terror management theory, the authors propose a model of a tripartite security system consisting of dynamically interrelated attachment, self-esteem, and worldview processes. Four studies are presented that, combined with existing evidence, support the prediction derived from the model that threats to one component of the security system result in compensatory defensive activation of other components. Further, the authors predicted and found that individual differences in attachment style moderate the defenses. In Studies 1 and 2, attachment threats motivated worldview defense among anxiously attached participants and motivated self-enhancement (especially among avoidant participants), effects similar to those caused by mortality salience. In Studies 3 and 4, a worldview threat and a self-esteem threat caused attachment-related proximity seeking among fearful participants and avoidance of proximity among dismissing participants. The authors' model provides an overarching framework within which to study attachment, self-esteem, and worldviews.

  8. Two new species of coccidia (Apicomplexa: Eimeriidae) from leaf-tailed geckos, Uroplatus spp. (Sauria: Gekkonidae) from Madagascar, including a new host of Eimeria brygooi Upton & Barnard, 1987.

    Science.gov (United States)

    McAllister, Chris T; Scott Seville, R; Hartdegen, Ruston

    2016-10-01

    During May and June 2015, four common leaf-tailed geckos, Uroplatus fimbriatus (Schneider), five satanic leaf-tailed geckos, Uroplatus phantasticus (Boulenger), and four mossy leaf-tailed geckos, Uroplatus sikorae Boettger originally collected from Madagascar and housed at the Dallas Zoo, USA, had their faeces examined for coccidian parasites. Eight (62%) geckos were found to be passing oöcysts, including a new eimerian, a new isosporan and a previously described eimerian. Three of four (75%) U. fimbratus (type-host) and one of five (20%) U. phantasticus were infected with Eimeria schneideri n. sp.; oöcysts were subspheroidal to ellipsoidal with a bi-layered wall and measured (mean length × width, L × W) 15.1 × 13.5 µm, with a length/width (L/W) ratio of 1.1. A micropyle and oöcyst residuum were absent but one to many polar granules were present. Sporocysts were ovoidal, 6.9 × 5.3 µm, L/W = 1.3. Stieda, sub-Stieda and para-Stieda bodies were absent. A globular sporocyst residuum was present as dispersed granules. Four of five (80%) U. phantasticus harboured Isospora boulengeri n. sp.; oöcysts were subpheroidal to ellipsoidal with a bi-layered wall and measured 17.3 × 16.0 µm, L/W = 1.1. A micropyle and oöcyst residuum were absent but a polar granule was present. Sporocysts were ellipsoidal, 9.5 × 6.9 µm, L/W = 1.4. Stieda and sub-Stieda bodies were present but a para-Stieda body was absent. A globular sporocyst residuum was present with dispersed granules. In addition, one of four (25%) U. sikorae was infected with an eimerian indistinguishable from Eimeria brygooi Upton & Barnard, 1987, previously reported from Madagascar day gecko, Phelsuma grandis Gray and golddust day gecko, Phelsuma laticauda (Boettger) from Madagascar. These are the first coccidians described from Uroplatus spp.

  9. Skipping breakfast and overweight in 2-and 5-year-old Dutch children-the GECKO Drenthe cohort

    NARCIS (Netherlands)

    Kupers, L. K.; de Pijper, J. J.; Sauer, P. J. J.; Stolk, R. P.; Corpeleijn, E.

    Skipping breakfast is associated with higher BMI in children aged 5 years and older. However, not much is known about this association in younger children. In the Dutch GECKO Drenthe birth cohort we examined the association between breakfast skipping and objectively measured overweight at the age of

  10. The gecko visual pigment: a pH indicator with a salt effect.

    Science.gov (United States)

    Crescitelli, F

    1981-12-01

    1. Unlike rhodopsin, the extracted 521-pigment of the Tokay gecko (Gekko gekko) is pH-sensitive and changes its spectral absorbance in the pH range of 4.5-7.3. The colour change is reversible and pH can be employed to adjust the spectral maximum anywhere between 490 nm and its native location at 521 nm.2. The hypsochromic shift with increasing acidity is opposite to that expected for the protonation of the Schiff base nitrogen and suggests an action on the secondary system of interacting charges that have long been postulated to adjust vertebrate visual pigment colour within the visible spectrum.3. Chloride ions modulate this pH effect in a systematic and significant manner. For the pigment extracted in the chloride-deficient state the colour change occurs in the pH range of 6.0-7.0, the midpoint being close to 6.5, suggesting the possible participation of the imidazole group of histidine as the functional moiety. With added NaCl the colour shifts to the region below pH 6.2.4. The modulating action of chloride is postulated to be a conformational change of the opsin leading to a shift of the secondary interacting site from one functional group to another or else to a change in pK of a single group due to the conformational alteration of the electrostatics of the system.5. At pH values between 7.5 and 9.0 a different mechanism becomes apparent. In this region a decrease occurs in the photopigment density as well as a shift in absorbance toward the blue. This alkaline effect is readily reversed either by adding NaCl or else by lowering the pH. Along with the other protective effects of chloride these ions serve to reduce or prevent this alkaline loss in density.6. Associated with this reversible photopigment loss is a reversible appearance of a product with a maximum at about 366 nm. The spectrum of this product is like that produced by the addition of 11-cis retinal to the extract. Acidification of the alkaline preparation leads to a restitution of the photopigment

  11. Effects of testosterone on sexual behavior and morphology in adult female leopard geckos, Eublepharis macularius.

    Science.gov (United States)

    Rhen, T; Ross, J; Crews, D

    1999-10-01

    The leopard gecko, Eublepharis macularius, is a species in which testosterone (T) is the primary circulating sex hormone in adults of both sexes. There are, however, sex differences in T physiology. Whereas males have prolonged periods with high T levels, T levels cycle in accord with follicular development in females. Specifically, T concentration increases during vitellogenesis, drops after ovulation, and then remains at previtellogenic levels until eggs are laid and the next follicular cycle begins. To determine the function of T in females, we manipulated both the level and the duration of T elevation using Silastic implants in intact, adult female leopard geckos. Females had low ( approximately 1 ng/ml), medium ( approximately 100 ng/ml), or high ( approximately 200 ng/ml) T levels for either a short (8 days) or a long (35 days) duration. Behavior tests with males were conducted on days 1-5 in the short-duration group or on days 29-33 in the long-duration group. For both short- and long-duration groups, T treatment decreased attractivity in females with medium and high T levels compared to females with low T levels. In contrast, females with a medium T level were more receptive than females with a low T level in the short-duration group. Females in the long-duration group were unreceptive regardless of T level. Females treated for a long duration also displayed more aggression toward and evoked more aggression from males than short duration females. Short-duration T treatment had no masculinizing effect on female morphology, whereas medium and high T levels for a long duration induced development of hemipenes. Overall, these results suggest that T can both increase and decrease sexual behaviors in the female leopard gecko.

  12. Gecko CD59 Is Implicated in Proximodistal Identity during Tail Regeneration

    Science.gov (United States)

    Jiang, Shengjuan; Zhou, Weijuan; Liu, Yan; Wang, Yingjie; Gu, Qing; Gu, Yun; Dong, Yingying; Liu, Mei; Gu, Xingxing; Ding, Fei; Gu, Xiaosong

    2011-01-01

    Several adult reptiles, such as Gekko japonicus, have the ability to precisely re-create a missing tail after amputation. To ascertain the associated acquisition of positional information from blastemal cells and the underlying molecular mechanism of tail regeneration, a candidate molecule CD59 was isolated from gecko. CD59 transcripts displayed a graded expression in the adult gecko spinal cord with the highest level in the anterior segment, with a stable expression along the normal tail. After tail amputation, CD59 transcripts in the spinal cord proximal to the injury sites increased markedly at 1 day and 2 weeks; whereas in the regenerating blastema, strong CD59 positive signals were detected in the blastemal cells anterior to the blastema, with a gradual decrease along the proximodistal (PD) axis. When treated with RA following amputation, CD59 transcripts in the blastema were up-regulated. PD confrontation assays revealed that the proximal blastema engulfed the distal one after in vitro culture, and rabbit-anti human CD59 antibody was able to block this PD engulfment. Overexpression of the CD59 during tail regeneration causes distal blastemal cells to translocate to a more proximal location. Our results suggest that position identity is not restricted to amphibian limb regeneration, but has already been established in tail blastema of reptiles. The CD59, a cell surface molecule, acted as a determinant of proximal–distal cell identity. PMID:21464923

  13. Two new species of coccidia (Apicomplexa: Eimeriidae) from leaf-tailed geckos, Uroplatus spp. (Sauria: Gekkonidae) from Madagascar, including a new host of Eimeria brygooi Upton and Barnard, 1987

    Science.gov (United States)

    McAllister, Chris T.; Seville, R. Scott; Hartdegen, Ruston

    2016-01-01

    During May and June 2015, four common leaf-tailed geckos, Uroplatus fimbriatus (Schneider), five satanic leaf-tailed geckos, Uroplatus phantasticus (Boulenger), and four mossy leaf-tailed geckos, Uroplatus sikorae Boettger originally collected from Madagascar and housed at the Dallas Zoo, USA, had their faeces examined for coccidian parasites. Eight (62%) geckos were found to be passing oöcysts, including a new eimerian, a new isosporan and a previously described eimerian. Three of four (75%) U. fimbratus (type host) and one of five (20%) U. phantasticus were infected with Eimeria schneideri n. sp.; oöcysts were subspheroidal to ellipsoidal with a bi-layered wall and measured (length × width, L × W) 15.1 × 13.5 µm, with a length/width (L/W) ratio of 1.1. A micropyle and oöcyst residuum were absent but 1–many polar granules were present. Sporocysts were ovoidal, 6.9 × 5.3 µm, L/W 1.3. Stieda, sub-Stieda and para-Stieda bodies were absent. A globular sporocyst residuum was present as dispersed granules. Four of five (80%) U. phantasticus harbored Isospora boulengeri n. sp.; oöcysts were subpheroidal to ellipsoidal with a bi-layered wall and measured 17.3 × 16.0 µm, L/W 1.1. A micropyle and oöcyst residuum were absent but a polar granule was present. Sporocysts were ellipsoidal, 9.5 × 6.9 µm, L/W 1.4. Stieda and sub-Stieda bodies were present but a para-Stieda body was absent. A globular sporocyst residuum was present with dispersed granules. In addition, one of four (25%) U. sikorae was infected with an eimerian indistinguishable from Eimeria brygooi Upton and Barnard, 1987, previously reported from Madagascar day gecko, Phelsuma grandis Gray and golddust day gecko, Phelsuma laticauda (Boettger) from Madagascar. These are the first coccidians described from Uroplatus spp. PMID:27638735

  14. Visual cycle and its metabolic support in gecko photoreceptors.

    Science.gov (United States)

    Kolesnikov, A V; Ala-Laurila, P; Shukolyukov, S A; Crouch, R K; Wiggert, B; Estevez, M E; Govardovskii, V I; Cornwall, M C

    2007-02-01

    Photoreceptors of nocturnal geckos are transmuted cones that acquired rod morphological and physiological properties but retained cone-type phototransduction proteins. We have used microspectrophotometry and microfluorometry of solitary isolated green-sensitive photoreceptors of Tokay gecko to study the initial stages of the visual cycle within these cells. These stages are the photolysis of the visual pigment, the reduction of all-trans retinal to all-trans retinol, and the clearance of all-trans retinol from the outer segment (OS) into the interphotoreceptor space. We show that the rates of decay of metaproducts (all-trans retinal release) and retinal-to-retinol reduction are intermediate between those of typical rods and cones. Clearance of retinol from the OS proceeds at a rate that is typical of rods and is greatly accelerated by exposure to interphotoreceptor retinoid-binding protein, IRBP. The rate of retinal release from metaproducts is independent of the position within the OS, while its conversion to retinol is strongly spatially non-uniform, being the fastest at the OS base and slowest at the tip. This spatial gradient of retinol production is abolished by dialysis of saponin-permeabilized OSs with exogenous NADPH or substrates for its production by the hexose monophosphate pathway (NADP+glucose-6-phosphate or 6-phosphogluconate, glucose-6-phosphate alone). Following dialysis by these agents, retinol production is accelerated by several-fold compared to the fastest rates observed in intact cells in standard Ringer solution. We propose that the speed of retinol production is set by the availability of NADPH which in turn depends on ATP supply within the outer segment. We also suggest that principal source of this ATP is from mitochondria located within the ellipsoid region of the inner segment.

  15. Sex steroid levels across the reproductive cycle of female leopard geckos, Eublepharis macularius, from different incubation temperatures.

    Science.gov (United States)

    Rhen, T; Sakata, J T; Zeller, M; Crews, D

    2000-05-01

    Incubation temperature during embryonic development determines gonadal sex in many reptiles, including the leopard gecko (Eublepharis macularius). In this study, we examined the hormonal and behavioral changes that occur during the reproductive cycle of female leopard geckos from four (i.e., 26, 30, 32.5, and 34 degrees C) incubation temperatures. Controlling for reproductive status, plasma levels of dihydrotestosterone (DHT), testosterone (T), and progesterone (P) varied with incubation temperature but estradiol 17-beta (E2) levels did not. Controlling for the effects of incubation temperature, DHT and T levels were low when females were previtellogenic, increased slightly during early vitellogenesis, increased dramatically during late vitellogenesis (i.e., prior to ovulation), and then decreased to previtellogenic levels after ovulation. In contrast, E2 levels increased gradually from the previtellogenic stage to the early vitellogenic stage, peaked during late vitellogenesis, and decreased to previtellogenic levels after ovulation. Levels of P increased from the previtellogenic stage to the early vitellogenic stage, remained elevated during late vitellogenesis, and then decreased after ovulation. Moreover, we determined that females were not sexually receptive when previtellogenic, were somewhat receptive during early vitellogenesis (approximately 20% receptive), were most receptive during late vitellogenesis (approximately 80% receptive), and were again unreceptive after ovulation. Incubation temperature did not influence receptivity. Overall, these data show that hormone levels and behavior change coordinately during the reproductive cycle. Although incubation temperature has persistent effects on endocrine physiology in adult female leopard geckos, these effects are modest compared to hormonal changes across the reproductive cycle.

  16. Development of the Gecko (Pachydactylus turneri) Animal Model during Foton M-2 to Study Comparative Effects of Microgravity in Terrestrial and Aquatic Organisms

    Science.gov (United States)

    Almeida, E. A.; Roden, C.; Phillips, J. A.; Globus, R. K.; Searby, N.; Vercoutere, W.; Morey-Holton, E.; Gulimova, V.; Saveliev, S.; Tairbekov, M.; hide

    2006-01-01

    Terrestrial organisms exposed to microgravity during spaceflight experience degeneration in bone, muscle, and possibly other tissues that require gravity-mediated mechanical stimulation for normal regenerative growth. In the Gecko experiment aboard Foton M-2, we flew for the first time, five terrestrial Pachydactylus turneri specimens to develop a model of microgravity effects comparable to the newt Pleurodeles waltl, a well-established model organism for spaceflight. These lower vertebrate species have similar body plans and size, are poikilothermic, have tissue regenerative ability, and are adapted to moderate periods of fasting. Furthermore the gecko (Pachydactylus) can also survive prolonged periods without water. In pre-flight control experiments and after a 16-day Foton M-2 spaceflight without food or water, the geckos were recovered and showed no apparent negative health effects. However, detailed analysis of bone mass and architecture by micro Computed Tomography { pCT), showed that both synchronous control and spaceflight animals lost significant amounts of cancellous bone in the distal femur and humerus relative to basal controls. In addition, cell cycle analysis of 30h post-flight liver tissue reveals a shift of DNA content from G2 and S to G1, both in spaceflight and synchronous controls. Together, these results suggest that housing conditions alone induce rapid catabolism of cancellous bone and reduced normal tissue regeneration. Further use of the gecko Puchydactylus turneri as a spaceflight model requires modification of housing conditions, possibly by including water and food, or changing other factors such as eliminating housing stresses to obtain stable bone structure and tissue regeneration during spaceflight experiments.

  17. Prevalence and diversity of Hepatozoon in native and exotic geckos from Brazil.

    Science.gov (United States)

    Harris, David James; Borges-Nojosa, Diva Maria; Maia, João Pedro

    2015-02-01

    Hepatozoon is a genus of hemogregarines constituting the most widespread and common reptile hemoparasite. Although various molecular assessments of these parasites have been conducted in lizards from Africa and Europe, similar studies are needed for South American lizards. Through amplification and sequencing of fragments of the 18S rRNA gene, we assess the prevalence of Hepatozoon parasites in 230 geckos from South America, including the endemic species Hemidactylus agrius, Hemidactylus brasilianus, Lygodactylus klugei, Phyllopezus pollicaris, Phyllopezus periosus, and an exotic species, Hemidactylus mabouia . We found an overall low prevalence of Hepatozoon infection (7/230, 3%) with only 3 of the 6 host species infected with Hepatozoon ( Hemidactylus mabouia , P. pollicaris, and P. periosus). Within the 7 infected host samples, 5 genetically distinct lineages of Hepatozoon parasites were identified, only 1 of which was similar to previously published haplotypes. Thus, although prevalence is low, genetically based diversity of Hepatozoon in geckos from South America is very high. Three of these lineages appear basal to 1 of the major clades of Hepatozoon, suggesting that this clade might have originated in South America, and thereby indicating a potential phylogeographic pattern that had not been previously identified. Future studies should assess the distribution and competence of invertebrate hosts in the regions analyzed, and Hepatozoon diversity in other less well-known regions of the world.

  18. An energetic perspective on tissue regeneration: The costs of tail autotomy in growing geckos.

    Science.gov (United States)

    Starostová, Zuzana; Gvoždík, Lumír; Kratochvíl, Lukáš

    2017-04-01

    Tail autotomy is a crucial antipredatory lizard response, which greatly increases individual survival, but at the same time also compromises locomotor performance, sacrifices energy stores and induces a higher burden due to the ensuing response of regenerating the lost body part. The potential costs of tail autotomy include shifts in energy allocation and metabolic rates, especially in juveniles, which invest their energy primarily in somatic growth. We compared the metabolic rates and followed the growth of juvenile males with and without regenerating tails in the Madagascar ground gecko (Paroedura picta), a nocturnal ground-dwelling lizard. Geckos with intact tails and those that were regrowing them grew in snout-vent-length at similar rates for 22weeks after autotomy. Tail regeneration had a negligible influence on body mass-corrected metabolic rate measured at regular intervals throughout the regenerative process. We conclude that fast-growing juveniles under the conditions of unrestricted food can largely compensate for costs of tail loss and regeneration in their somatic growth without a significant impact on the total individual body mass-corrected metabolic rate. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Intermediate filament immunohistochemistry of astroglial cells in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Lazzari, Maurizio; Franceschini, Valeria

    2005-11-01

    The distribution of intermediate filament molecular markers, glial fibrillary acidic protein (GFAP) and vimentin, has been studied in the central nervous system (CNS) of the adult leopard gecko, Eublepharis macularius. This immunohistochemical study points out the presence of different astroglial cell types. The main pattern is constituted by ependymal radial glia, which have their cell bodies located in the ependymal layer throughout the brain ventricular system. Radial glia proper or radial astrocytes show their cell bodies displaced from the ependymal layer into a periependymal zone and are observed only in the spinal cord. Star-shaped astrocytes are scarce. They are detected in the ventral and lateral regions of the diencephalon and mesencephalon, in the superficial layer of the optic tectum, in the ventral medulla oblongata, and in the ventral and lateral spinal cord. In the different regions of the CNS, the staining intensity appears not to be identical even in the same cellular type. The results reported in the present study show an heterogeneous feature of the astroglial pattern in E. macularius.

  20. Electron attachment cross sections obtained from electron attachment spectroscopy

    International Nuclear Information System (INIS)

    Popp, P.; Baumbach, J.I.; Leonhardt, J.W.; Mothes, S.

    1988-01-01

    Electron capture detectors have a high sensitivity for substances with high thermal electron attachment cross sections. The electron attachment spectroscopy makes it possible to change the mean electron energy in such a way that the maximum for dissociative electron attachment is reached. Thus, best operation modes of the detection system as well as significant dependencies of electron attachment coefficients are available. Cross sections for electron attachment as a function of the electron energy are obtained with the knowledge of electron energy distribution functions from Boltzmann equation analysis by a special computer code. A disadvantage of this electron attachment spectroscopy is the superposition of space charge effects due to the decrease of the electron drift velocity with increasing mean electron energy. These influences are discussed. (author)

  1. Activation of the attachment system and mentalization in depressive and healthy individuals: An experimental control study

    Directory of Open Access Journals (Sweden)

    Fizke Ella

    2013-01-01

    Full Text Available From a developmental and clinical point of view attachment theory and mentalization are closely connected and have become increasingly important to understand the origins of psychopathological development. However, very little is known about how exactly different inner working models of attachment are related to diverse mentalizing abilities and this is particularly true for adult populations - healthy as well as clinical populations. In the present study we investigated this relation with a sample of inpatients diagnosed with depression and a sample of healthy individuals. In an experimental setting the attachment system was activated using the Adult Attachment Projective Picture System (AAP. Mentalization was assessed during activation and in comparison to a control condition using a modified version of the Reading the Mind in the Eyes Test (RMET. We expected that an activation of the attachment system i diminishes the capacity to take another’s perspective in individuals with unresolved state of mind, ii has no impact in individuals with secure attachment representation and iii is dependent of clinical status in individuals with insecure (but organized working models of attachment. Overall, these hypotheses were confirmed. However, the impact of clinical status on mentalization in insecure attachment has to be further explored. We summarize that attachment state of mind has a mediating influence on mentalization basically in such situations where the attachment system is activated.

  2. Identification and expression analysis of peroxisome proliferator-activated receptors cDNA in a reptile, the leopard gecko (Eublepharis macularius).

    Science.gov (United States)

    Kato, Keisuke; Oka, Yoshitaka; Park, Min Kyun

    2008-05-01

    Despite the physiological and evolutionary significance of lipid metabolism in amniotes, the molecular mechanisms involved have been unclear in reptiles. To elucidate this, we investigated peroxisome proliferators-activated receptors (PPARs) in the leopard gecko (Eublepharis macularius). PPARs belong to a nuclear hormone-receptor family mainly involved in lipid metabolism. Although PPARs have been widely studied in mammals, little information about them is yet available from reptiles. We identified in the leopard gecko partial cDNA sequences of PPARalpha and beta, and full sequences of two isoforms of PPARgamma. This is the first report of reptilian PPARgamma mRNA isoforms. We also evaluated the organ distribution of expression of these genes by using RT-PCR and competitive PCR. The expression level of PPARalpha mRNA was highest in the large intestine, and moderate in the liver and kidney. The expression level of PPARbeta mRNA was highest in the kidney and large intestine, and moderate in the liver. Similarly to the expression of human PPARgamma isoforms, PPARgammaa was expressed ubiquitously, whereas the expression of PPARgammab was restricted. The highest levels of their expression, however, were observed in the large intestine, rather than in the adipose tissue as in mammals. Taken together, these results showed that the profile of PPARbeta mRNA expression in the leopard gecko is similar to that in mammals, and that those of PPAR alpha and gamma are species specific. This may reflect adaptation to annual changes in lipid storage due to seasonal food availability.

  3. Importance of loading and unloading procedures for gecko-inspired controllable adhesives.

    Science.gov (United States)

    Tamelier, John; Chary, Sathya; Turner, Kimberly L

    2013-08-27

    The importance of loading and unloading procedures has been shown in a variety of different methods for biological dry adhesives, such as the fibers on the feet of the Tokay gecko, but biomimetic dry adhesives have yet to be explored in a similar manner. To date, little work has systematically varied multiple parameters to discern the influence of the testing procedure, and the effect of the approach angle remains uncertain. In this study, a synthetic adhesive is moved in 13 individual approach and retraction angles relative to a flat substrate as well as 9 different shear lengths to discern how loading and unloading procedures influence the preload, adhesion, and shear/friction forces supported. The synthetic adhesive, composed of vertical 10 μm diameter semicircular poly(dimethylsiloxane) fibers, is tested against a 4 mm diameter flat glass puck on a home-built microtribometer using both vertical approach and retraction tests and angled approach and retraction tests. The results show that near maximum adhesion and friction can be obtained for most approach and retraction angles, provided that a sufficient shear length is performed. The results also show that the reaction forces during adhesive placement can be significantly reduced by using specific approach angles, resulting for the vertical fibers in a 38-fold increase in the ratio of adhesion force to preload force, μ', when compared to that when using a vertical approach. These results can be of use to those currently researching gecko-inspired adhesives when designing their testing procedures and control algorithms for climbing and perching robots.

  4. Lungs of the gecko Rhacodactylus leachianus (Reptilia: Gekkonidae): a correlative gross anatomical and light and electron microscopic study.

    Science.gov (United States)

    Perry, S F; Bauer, A M; Russell, A P; Alston, J T; Maloney, J E

    1989-01-01

    The lungs of the New Caldeonian gecko Rhacodactylus leachianus were examined by means of gross dissection and light and electron microscopy. This tropical species, which is the largest living gecko, possesses two simple, single-chambered lungs. Right and left lungs are of similar size and shape. The lung volume (27.2 ml.100 g-1) is similar to that of the tokay (Gekko gecko) but differs in that the gas exchange tissue is approximately homogeneously distributed, and the parenchymal units (ediculae) are very large, approximately 2 mm in diameter. The parenchymal depth varies according to the location in the lung, being deepest near the middle of the lung and shallowest caudally. Scanning and transmission electron microscopy reveal an unusual distribution of ciliated cells in patches on the edicular walls as well as on the trabeculae. Secretory cells are very numerous, particularly in the bronchial epithelium, where they greatly outnumber the ciliated cells. The secretory cells form a morphological continuum characterized by small secretory droplets apically and large vacuoles basally. This continuum includes cells resembling type II pneumocytes but which are devoid of lamellar bodies. Type I pneumocytes similar to those of other reptiles cover the respiratory capillaries, where they form a thin, air-blood barrier together with the capillary endothelial cells and the fused basement laminae. The innervation, musculature, and vascular distribution in R. leachianus are also characterized. Apparent simplification of the lungs in this taxon may be related to features of its sluggish habits, whereas peculiarities of cell and tissue composition may reflect demands of its mesic habitat.

  5. Attachment and prejudice.

    Science.gov (United States)

    Carnelley, Katherine B; Boag, Elle M

    2018-04-16

    There is a paucity of research that examines prejudice from an attachment theory perspective. Herein we make theoretical links between attachment patterns and levels of prejudice. Perceptions of outgroup threat, which activate the attachment system, are thought to lead to fear and prejudice for those high in attachment anxiety, and to distancing and prejudice for those high in attachment avoidance. We review the literature that examines the associations between attachment patterns and prejudice; evidence from attachment priming studies suggests a causal role of attachment security in reducing prejudice. We identify several mediators of these links: empathy, negative emotions, trust, social dominance orientation, romanticism, and contact quality. Future research should manipulate potential mediators and use psychophysiological assessments of threat. Copyright © 2018 Elsevier Ltd. All rights reserved.

  6. Modeling of the Gecko's skin microfibrillar structures using the Immersed Boundary method via DNS

    Science.gov (United States)

    Arenas, Isnardo; Carrasquillo, Kenneth; Leonardi, Stefano; Araya, Guillermo; Hussain, Fazle; Castillo, Luciano

    2013-11-01

    There is a current interest in surfaces that mimic the skin of some species (i.e., sharks, dolphins and geckos) in order to achieve drag reduction. The surface considered is based on the microfribrillar structures of a gecko's skin (Aksak et al. 2008). The structures are modeled by means of the immersed boundary method proposed by Fadlun et al. (2000). Direct simulations are performed to predict flow dynamics with a Reynolds number of 7000 based on the height of the channel and centerline velocity. The ratio of the height of the structure with respect to the height of the channel is approximately 0.05. The main motivation is to study how the microfribillar structures affect the momentum transfer from the viscous layer to the outer layer. The surface shows a reduction of the area affected by the shear stress due to the cavities formed by the pattern. As expected, the cavities create a low velocity zone thus decreasing the Reynolds shear stresses. Lambda-2 and Q-criterion were implemented to identify the elongated streamwise vortices. The results show that when compared to a flat channel the microfribillar structures tend to preserve these streamwise vortices instead of bursting into the outer layer which is a source of drag increase.

  7. Adhesion switch on a gecko-foot inspired smart nanocupule surface

    Science.gov (United States)

    Song, Wenlong

    2014-10-01

    A gecko-foot inspired nanocupule surface prepared by an AAO template covering method was composed of poly(N-isopropylacrylamide) and polystyrene blend. Both superhydrophobicity and high adhesion force were exhibited on the PNIPAm/PS film at room temperature. Moreover, by controlling the temperature, the wettability of the film could be switched between 138.1 +/- 5.5° and 150.6 +/- 1.5°, and the adhesion force could also be correspondingly tuned accurately by temperature. This reversibility in both wettability and adhesion force could be used to construct smart devices for fine selection of water droplets. The proof-of-concept was demonstrated by the selective catching of precise weight controlled water droplets at different temperatures. This work could help us to design new type of devices for blood bioanalysis or lossless drug transportation.A gecko-foot inspired nanocupule surface prepared by an AAO template covering method was composed of poly(N-isopropylacrylamide) and polystyrene blend. Both superhydrophobicity and high adhesion force were exhibited on the PNIPAm/PS film at room temperature. Moreover, by controlling the temperature, the wettability of the film could be switched between 138.1 +/- 5.5° and 150.6 +/- 1.5°, and the adhesion force could also be correspondingly tuned accurately by temperature. This reversibility in both wettability and adhesion force could be used to construct smart devices for fine selection of water droplets. The proof-of-concept was demonstrated by the selective catching of precise weight controlled water droplets at different temperatures. This work could help us to design new type of devices for blood bioanalysis or lossless drug transportation. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr04090b

  8. Effects of gonadal sex and incubation temperature on the ontogeny of gonadal steroid concentrations and secondary sex structures in leopard geckos, Eublepharis macularius.

    Science.gov (United States)

    Rhen, Turk; Sakata, Jon T; Crews, David

    2005-07-01

    Incubation temperature during embryonic development determines gonadal sex in the leopard gecko (Eublepharis macularius). Incubation temperature and gonadal sex jointly influence the display of sexual and agonistic behavior in adult leopard geckos. These differences in adult behavior are organized prior to sexual maturity, and it is plausible that post-natal hormones influence neural and behavioral differentiation. Here we assessed incubation temperature and sex effects on sex steroid levels in leopard geckos at 2, 10, and 25 weeks of age and monitored the development of male secondary sex structures. Males had significantly higher androgen concentrations at all time points, whereas females had significantly higher 17beta-estradiol (E2) concentrations only at 10 and 25 weeks. Within males, age but not incubation temperature affected steroid levels and morphological development. Male androgen levels increased modestly by 10 and dramatically by 25 weeks of age, whereas E2 levels remained unchanged over this period. Most males had signs of hemipenes at 10 weeks of age, and all males had hemipenes and open preanal pores by 25 weeks of age. In females, age and incubation temperature affected E2 and dihydrotestosterone (DHT) but not T concentrations. Controlling for age, females from 34 degrees C have higher DHT and lower E2 levels than females from 30 degrees C. Further, E2 concentrations increased significantly from 2 to 10 weeks, after which E2 levels remained steady. Together, these results indicate that sexually dimorphic levels of steroids play a major role in the development of leopard gecko behavior and morphology. Furthermore, these data suggest that the organizational effects of incubation temperature on adult female phenotype could be, in part, mediated by incubation temperature effects on steroid hormone levels during juvenile development.

  9. Tooth development in a model reptile: functional and null generation teeth in the gecko Paroedura picta

    Czech Academy of Sciences Publication Activity Database

    Zahradníček, Oldřich; Horáček, I.; Tucker, A. S.

    2012-01-01

    Roč. 221, č. 3 (2012), s. 195-208 ISSN 0021-8782 R&D Projects: GA ČR(CZ) GAP305/12/1766 Grant - others:GA AV ČR(CZ) KJB601110910 Program:KJ Institutional research plan: CEZ:AV0Z50390703 Institutional support: RVO:68378041 Keywords : cusps * gecko * null generation teeth Subject RIV: EA - Cell Biology Impact factor: 2.357, year: 2012

  10. Cytochrome oxidase activity in the preoptic area correlates with differences in sexual behavior of intact and castrated male leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Sakata, J T; Crews, D

    2004-08-01

    Although the utility of analyzing behavioral experience effects on neural cytochrome oxidase (CO) activity is well recognized, the behavioral correlates of endogenous differences in CO activity have rarely been explored. In male leopard geckos (Eublepharis macularius), the incubation temperature experienced during embryogenesis (IncT) and age affect CO activity in the preoptic area (POA), an area that modulates copulatory behavior. In this study, the authors assessed whether differences in POA CO activity correlate with differences in sexual behavior in intact and castrated geckos. Males with IncT- and age-dependent increases in POA CO activity mounted females with shorter latencies while intact and after castration and ejaculated more frequently after castration. The authors discuss the predictive value of CO activity and propose similar parallels in other species.

  11. Lateralization in escape behaviour at different hierarchical levels in a gecko: Tarentola angustimentalis from Eastern Canary Islands.

    Directory of Open Access Journals (Sweden)

    Enrique García-Muñoz

    Full Text Available At the individual level, to be behaviourally lateralized avoids costly duplication of neural circuitry and decreases possible contradictory order from the two brain hemispheres. However, being prey behaviour lateralized at higher hierarchical levels could generate different negative implications, especially if predators are able to make predictions after multiple encounters. These conflicting pressures, namely between the advantages for individuals and the disadvantages for populations could be concealed if higher-level lateralization would arise from the combination of lateralized behaviours of individuals which are mutually dependent. Here, we investigated the lateralization patterns in the escape behaviour of the gecko Tarentola angustimentalis undergoing a predatory attack simulation in a "T" maze experiment. Results showed that gecko populations displayed different degrees of lateralization, with an overall dominance of right-biased individuals. This trend is similar to that observed in the Podarcis wall lizards, which share predators with Tarentola. In addition, different morphological parameters plausible to affect refuge selection were explored in order to link directional asymmetries at morphological level with lateralization during refuge selection.

  12. Origin and in situ diversification in Hemidactylus geckos of the Socotra Archipelago.

    Science.gov (United States)

    Gómez-Díaz, Elena; Sindaco, Roberto; Pupin, Fabio; Fasola, Mauro; Carranza, Salvador

    2012-08-01

    The Socotra Archipelago is an ancient continental fragment of Gondwanan origin and one of the most isolated landforms on Earth and a biodiversity hot spot. Yet, the biogeography and evolutionary history of its endemic fauna still remain largely overlooked. We investigate the origin, tempo and mode of diversification in the Hemidactylus geckos of the Socotra Archipelago. Concatenated and multilocus species coalescent analyses of Hemidactylus from Arabia and North Africa indicate that the Hemidactylus from Socotra do not form a monophyletic group and branch as three independent and well-supported clades instead. Both the chronogram inferred using the gene tree approach of BEAST and the age-calibrated multilocus species tree obtained using *BEAST suggest that the origin of Hemidactylus from Socotra may have involved a first vicariance event that occurred in the Early Miocene, followed by two independent transoceanic dispersal events that occurred more recently, during the Pliocene. Within Socotra, we analysed patterns of genetic diversity, the phylogeography and the demographic history in all seven nonintroduced species of Hemidactylus. Results based on two mitochondrial and two nuclear loci from 144 individuals revealed complex patterns of within-island diversification and high levels of intra-species genetic divergence. The interplay of both historical and ecological factors seems to have a role in the speciation process of this group of geckos. Interestingly, the case of H. forbesii and H. oxyrhinus, which inhabit the island of Abd al Kuri with an area of 133 km(2), may represent one of the most extreme cases of intra-island speciation in reptiles ever reported. © 2012 Blackwell Publishing Ltd.

  13. Redescription of Cyrtodactylus fumosus (Müller, 1895 (Reptilia: Squamata: Gekkonidae, with a revised identification key to the bent-toed geckos of Sulawesi

    Directory of Open Access Journals (Sweden)

    Sven Mecke

    2016-12-01

    Full Text Available The binominal Cyrtodactylus fumosus has frequently been used for populations of bent-toed geckos occurring on some Indonesian islands, including Java, Bali, Sulawesi, and Halmahera. Unfortunately, incorrect usage of this name for different geographic lineages has resulted in confusion about the true identity of C. fumosus. Examination of the type specimen and additional specimens from Rurukan and Mount Masarang, North Sulawesi Province, Indonesia, revealed that this population is distinct from other forms heretofore called ‘fumosus’ by a combination of unique morphological characters. In order to stabilize the taxonomy of C. fumosus sensu stricto, and to prevent further confusion, we provide a comprehensive redescription of this species, whose distribution we herein restrict to North Sulawesi. Cyrtodactylus fumosus is one of the most distinctive species among the six bent-toed geckos recorded from Sulawesi, and it differs from Sulawesi congeners by the presence of (1 precloacofemoral scales, including three pore-bearing scales on each thigh, separated from 10 or 11 pore-bearing scales in the precloacal region by 9-11 interscales in males, (2 a precloacal groove in adult males, (3 flat dorsal tubercles in 4-7 irregularly arranged longitudinal rows at midbody, and (4 a distinct lateral fold lacking tubercles. We also provide a revised identification key to the bent-toed gecko species of Sulawesi.

  14. Distribution of androgen and estrogen receptor mRNA in the brain and reproductive tissues of the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Rhen, T; Crews, D

    2001-09-03

    Incubation temperature during embryonic development determines gonadal sex in the leopard gecko, Eublepharis macularius. In addition, both incubation temperature and gonadal sex influence behavioral responses to androgen and estrogen treatments in adulthood. Although these findings suggest that temperature and sex steroids act upon a common neural substrate to influence behavior, it is unclear where temperature and hormone effects are integrated. To begin to address this question, we identified areas of the leopard gecko brain that express androgen receptor (AR) and estrogen receptor (ER) mRNA. We gonadectomized adult female and male geckos from an incubation temperature that produces a female-biased sex ratio and another temperature that produces a male-biased sex ratio. Females and males from both temperatures were then treated with equivalent levels of various sex steroids. Region-specific patterns of AR mRNA expression and ER mRNA expression were observed upon hybridization of radiolabeled (35S) cRNA probes to thin sections of reproductive tissues (male hemipenes and female oviduct) and brain. Labeling for AR mRNA was very intense in the epithelium, but not within the body, of the male hemipenes. In contrast, expression of ER mRNA was prominent in most of the oviduct but not in the luminal epithelium. Within the brain, labeling for AR mRNA was conspicuous in the anterior olfactory nucleus, the lateral septum, the medial preoptic area, the periventricular preoptic area, the external nucleus of the amygdala, the anterior hypothalamus, the ventromedial hypothalamus, the premammillary nucleus, and the caudal portion of the periventricular nucleus of the hypothalamus. Expression of ER mRNA was sparse in the septum and was prominent in the ventromedial hypothalamus, the caudal portion of the periventricular nucleus of the hypothalamus, and a group of cells near the torus semicircularis. Many of these brain regions have been implicated in the regulation of hormone

  15. Karyotype Reorganization in the Hokou Gecko (Gekko hokouensis, Gekkonidae): The Process of Microchromosome Disappearance in Gekkota

    OpenAIRE

    Srikulnath, Kornsorn; Uno, Yoshinobu; Nishida, Chizuko; Ota, Hidetoshi; Matsuda, Yoichi

    2015-01-01

    The Hokou gecko (Gekko hokouensis: Gekkonidae, Gekkota, Squamata) has the chromosome number 2n = 38, with no microchromosomes. For molecular cytogenetic characterization of the gekkotan karyotype, we constructed a cytogenetic map for G. hokouensis, which retains the ancestral karyotype of Gekkota, with 86 functional genes, and compared it with cytogenetic maps for four Toxicofera species that have many microchromosomes (Elaphe quadrivirgata, Varanus salvator macromaculatus, Leiolepis reevesii...

  16. Temperature-dependent sex determination in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Viets, B E; Tousignant, A; Ewert, M A; Nelson, C E; Crews, D

    1993-05-01

    The leopard gecko, Eublepharis macularius, has temperature-dependent sex determination (TSD). Previous reports have shown that females are produced predominantly at cool incubation temperatures and males are produced predominantly at warm incubation temperatures (Pattern Ib). We report here that incubation at even higher temperatures (34 and 35 degrees C) produces mostly females (Pattern II). The lethal maximum constant incubation temperature for this species appears to be just above 35 degrees C. Although a previous study indicated that females from a warm incubation temperature (32 degrees C) failed to lay eggs, we found that 12 of 14 mature females incubated at 32.5 degrees C, and 5 of 6 mature females incubated at 34 degrees C produced fertile eggs and viable hatchlings.

  17. Identification and characterization of the reptilian GnRH-II gene in the leopard gecko, Eublepharis macularius, and its evolutionary considerations.

    Science.gov (United States)

    Ikemoto, Tadahiro; Park, Min Kyun

    2003-10-16

    To elucidate the molecular phylogeny and evolution of a particular peptide, one must analyze not the limited primary amino acid sequences of the low molecular weight mature polypeptide, but rather the sequences of the corresponding precursors from various species. Of all the structural variants of gonadotropin-releasing hormone (GnRH), GnRH-II (chicken GnRH-II, or cGnRH-II) is remarkably conserved without any sequence substitutions among vertebrates, but its precursor sequences vary considerably. We have identified and characterized the full-length complementary DNA (cDNA) encoding the GnRH-II precursor and determined its genomic structure, consisting of four exons and three introns, in a reptilian species, the leopard gecko Eublepharis macularius. This is the first report about the GnRH-II precursor cDNA/gene from reptiles. The deduced leopard gecko prepro-GnRH-II polypeptide had the highest identities with the corresponding polypeptides of amphibians. The GnRH-II precursor mRNA was detected in more than half of the tissues and organs examined. This widespread expression is consistent with the previous findings in several species, though the roles of GnRH outside the hypothalamus-pituitary-gonadal axis remain largely unknown. Molecular phylogenetic analysis combined with sequence comparison showed that the leopard gecko is more similar to fishes and amphibians than to eutherian mammals with respect to the GnRH-II precursor sequence. These results strongly suggest that the divergence of the GnRH-II precursor sequences seen in eutherian mammals may have occurred along with amniote evolution.

  18. Bioadhesion of mussels and geckos: Molecular mechanics, surface chemistry, and nanoadhesives

    Science.gov (United States)

    Lee, Haeshin

    The adhesive strategies of living creatures are diverse, ranging from temporary to permanent adhesions with various functions such as locomotion, self-defense, communication, colony formation, and so on. The classic example of temporary adhesion is the gecko, which is known for its ability to walk along vertical and even inverted surfaces; this remarkable adhesion arises from the interfacial weak interactions of van der Waals and capillary forces. In contrast, a celerbrated example of permanent adhesion is found in marine mussels which secrete protein adhesives that function in aqueous environments without mechanical failure against turbulent conditions on the seashore. In addition, mussel adhesives stick to virtually all inorganic and organic surfaces. However, most commonly used man-made adhesives lack such unique adhesion properties compared to their natural counterparts. For example, many commercial adhesives quickly lose their adhesive strength when exposed to solvents, particularly water. The first part of this thesis focused on adhesion mechanics of mussels at a single-molecule level, in which the adhesive molecule showed surprisingly strong yet reversible adhesion on inorganic surfaces but exhibited irreversible covalent bond formation on organic surfaces. Strong and reversible adhesion on mucin surfaces was found, indicating potential application for drug delivery via mucus layers. Next, inspired by the mussel's versatile adhesion on a wide variety of material surfaces, a material-independent surface modification chemistry called 'polydopamine coating' is described. This concept was subsequently adapted to develop a surface-independent polymeric primer for layer-by-layer assembly of multifunctional coatings. Finally, a new bio-hybrid adhesive 'geckel' was developed by the functional combination of adhesion strategies of geckos and mussels. The new bio-inspired adhesive and material-independent surface chemistry can revolutionize the research areas such as

  19. Ceramic blade attachment system

    Science.gov (United States)

    Frey, G.A.; Jimenez, O.D.

    1996-12-03

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine flange having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine flange includes a first upstanding flange and a second upstanding flange having a groove formed between them. The turbine flange further includes a recess. Each of the first and second upstanding flanges have a plurality of bores therein. A turbine blade has a first member and a second member positioned in one of the groove and the recess. Each of the first member and the second member have a plurality of bores therein. A pin is positioned in respective ones of the plurality of bores in the first and second upstanding members and the first and second members and attach the blade to the turbine flange. The pin has a preestablished rate of thermal expansion being substantially equal to the rate of thermal expansion of the blade. 4 figs.

  20. Direct fabrication of bio-inspired gecko-like geometries with vat polymerization additive manufacturing method

    DEFF Research Database (Denmark)

    Davoudinejad, A.; M. Ribo, M.; Pedersen, D. B.

    2018-01-01

    on. The geometry and fabrication of these surfaces are still under research. In this study, the feasibility of using direct fabrication of microscale features by Additive Manufacturing (AM) processes was investigated. The investigation was carried out using a specifically designed vat...... photopolymerization AM machine-tool suitable for precision manufacturing at the micro dimensional scale which has previously been developed, built and validated at the Technical University of Denmark. It was shown that it was possible to replicate a simplified surface inspired by the Tokay gecko, the geometry...

  1. Armored geckos: A histological investigation of osteoderm development in Tarentola (Phyllodactylidae) and Gekko (Gekkonidae) with comments on their regeneration and inferred function.

    Science.gov (United States)

    Vickaryous, M K; Meldrum, G; Russell, A P

    2015-11-01

    Osteoderms are bone-rich organs found in the dermis of many scleroglossan lizards sensu lato, but are only known for two genera of gekkotans (geckos): Tarentola and Gekko. Here, we investigate their sequence of appearance, mode of development, structural diversity and ability to regenerate following tail loss. Osteoderms were present in all species of Tarentola sampled (Tarentola annularis, T. mauritanica, T. americana, T. crombei, T. chazaliae) as well as Gekko gecko, but not G. smithii. Gekkotan osteoderms first appear within the integument dorsal to the frontal bone or within the supraocular scales. They then manifest as mineralized structures in other positions across the head. In Tarentola and G. gecko, discontinuous clusters subsequently form dorsal to the pelvis/base of the tail, and then dorsal to the pectoral apparatus. Gekkotan osteoderm formation begins once the dermis is fully formed. Early bone deposition appears to involve populations of fibroblast-like cells, which are gradually replaced by more rounded osteoblasts. In T. annularis and T. mauritanica, an additional skeletal tissue is deposited across the superficial surface of the osteoderm. This tissue is vitreous, avascular, cell-poor, lacks intrinsic collagen, and is herein identified as osteodermine. We also report that following tail loss, both T. annularis and T. mauritanica are capable of regenerating osteoderms, including osteodermine, in the regenerated part of the tail. We propose that osteoderms serve roles in defense against combative prey and intraspecific aggression, along with anti-predation functions. © 2015 Wiley Periodicals, Inc.

  2. Examining antecedents of infant attachment security with mothers and fathers: An ecological systems perspective☆

    Science.gov (United States)

    Lickenbrock, Diane M.; Braungart-Rieker, Julia M.

    2015-01-01

    Taking an ecological systems perspective, early parent–child relationships can be affected by interactions between systems where some are more proximally linked to the child than others. Socioeconomic status, a distal factor, is associated with social functioning during childhood, but research on its association with functioning during infancy, particularly attachment, is scant and inconsistent. Moreover, it is not clear how distal factors affect infant functioning. Other systems such as marital adjustment and parenting may moderate or mediate relations between distal factors and infant attachment. The current longitudinal study (n = 135) examined the role of various systems – parental resources, marital functioning, parental sensitivity and involvement – in early infancy (3-, 5-, 7-months) on infant–mother (12-months) and infant–father (14-months) attachment security. Findings supported moderating processes but in different ways for infant–mother versus infant–father dyads. Implications for future studies and interventions are discussed. PMID:25890261

  3. Ontogeny of metabolic rate and red blood cell size in eyelid geckos: species follow different paths.

    Directory of Open Access Journals (Sweden)

    Zuzana Starostová

    Full Text Available While metabolism is a fundamental feature of all organisms, the causes of its scaling with body mass are not yet fully explained. Nevertheless, observations of negative correlations between red blood cell (RBC size and the rate of metabolism suggest that size variation of these cells responsible for oxygen supply may play a crucial role in determining metabolic rate scaling in vertebrates. Based on a prediction derived from the Cell Metabolism Hypothesis, metabolic rate should increase linearly with body mass in species with RBC size invariance, and slower than linearly when RBC size increases with body mass. We found support for that prediction in five species of eyelid geckos (family Eublepharidae with different patterns of RBC size variation during ontogenetic growth. During ontogeny, metabolic rate increases nearly linearly with body mass in those species of eyelid geckos where there is no correlation between RBC size and body mass, whereas non-linearity of metabolic rate scaling is evident in those species with ontogenetic increase of RBC size. Our findings provide evidence that ontogenetic variability in RBC size, possibly correlating with sizes of other cell types, could have important physiological consequences and can contribute to qualitatively different shape of the intraspecific relationship between metabolic rate and body mass.

  4. Ontogeny of metabolic rate and red blood cell size in eyelid geckos: species follow different paths.

    Science.gov (United States)

    Starostová, Zuzana; Konarzewski, Marek; Kozłowski, Jan; Kratochvíl, Lukáš

    2013-01-01

    While metabolism is a fundamental feature of all organisms, the causes of its scaling with body mass are not yet fully explained. Nevertheless, observations of negative correlations between red blood cell (RBC) size and the rate of metabolism suggest that size variation of these cells responsible for oxygen supply may play a crucial role in determining metabolic rate scaling in vertebrates. Based on a prediction derived from the Cell Metabolism Hypothesis, metabolic rate should increase linearly with body mass in species with RBC size invariance, and slower than linearly when RBC size increases with body mass. We found support for that prediction in five species of eyelid geckos (family Eublepharidae) with different patterns of RBC size variation during ontogenetic growth. During ontogeny, metabolic rate increases nearly linearly with body mass in those species of eyelid geckos where there is no correlation between RBC size and body mass, whereas non-linearity of metabolic rate scaling is evident in those species with ontogenetic increase of RBC size. Our findings provide evidence that ontogenetic variability in RBC size, possibly correlating with sizes of other cell types, could have important physiological consequences and can contribute to qualitatively different shape of the intraspecific relationship between metabolic rate and body mass.

  5. Laryngotracheal morphology of Afro-Madagascan geckos: a comparative survey.

    Science.gov (United States)

    Russell, A P; Rittenhouse, D R; Bauer, A M

    2000-09-01

    The structural variation of the gekkonid larynx and trachea is examined within a representative subset of 17 species of Afro-Madagascan gekkonines to determine if there are underlying morphological correlates of vocalization. The documented morphology is compared to that of the tokay (Gekko gecko), which has previously been described. Data were obtained from gross anatomical observations, scanning electron microscopy, histological examinations and computer-generated, three-dimensional, skeletal reconstructions. Although there is limited variation among most Afro-Malagasy gekkonids, the larynges of Ptenopus garrulus and Uroplatus fimbriatus exhibit marked degrees of differentiation, suggesting that laryngeal and tracheal morphology may account for the documented vocal variability of gekkonid lizards. Cladistic analyses indicated that parallel adaptive trends characterize the laryngeal morphology of the examined taxa. Alternate designs and refinements to a model of gekkonid phonation are presented, and the evolution of acoustic communication in the Gekkonidae is considered. Copyright 2000 Wiley-Liss, Inc.

  6. Biological hydrogen production in continuous stirred tank reactor systems with suspended and attached microbial growth

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Nan-Qi; Tang, Jing; Liu, Bing-Feng; Guo, Wan-Qian [State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, No.202 Haihe Road, Harbin 150090 (China)

    2010-04-15

    Fermentative H{sub 2} production in continuous stirred tank reactor (CSTR) system with bacteria attached onto granular activated carbon (GAC) was designed to produce H{sub 2} continuously. The H{sub 2} production performances of CSTR with suspended and attached-sludge from molasses were examined and compared at various organic loading rates (8-40 g COD/L/d) at hydraulic retention time of 6 h under mesophilic conditions (35 C). Both reactor systems achieved ethanol-type fermentation in the pH ranges 4.5-4.8 and 3.8-4.4, respectively, while ORP ranges from -450 to -470 mV and from -330 to -350 mV, respectively. The hydrogen production rate in the attached system was higher compared to that of the suspended system (9.72 and 6.65 L/d/L, respectively) while specific hydrogen production rate of 5.13 L/g VSS/d was higher in the suspended system. The attached-sludge CSTR is more stable than the suspended-sludge CSTR with regard to hydrogen production, pH, substrate utilization efficiency and metabolic products (e.g., volatile fatty acids and ethanol) during the whole test. (author)

  7. Analysis of gene expression in gecko digital adhesive pads indicates significant production of cysteine- and glycine-rich beta-keratins.

    Science.gov (United States)

    Hallahan, David L; Keiper-Hrynko, Natalie M; Shang, Tanya Q; Ganzke, Thaya S; Toni, Mattia; Dalla Valle, Luisa; Alibardi, Lorenzo

    2009-01-15

    Microscopic bristles (setae) present on digital pads permit the adhesion and climbing of geckos. Keratins of setae of the lizard Gekko gecko (Tokay gecko) were analyzed by the isolation of expressed mRNAs and by the generation of an EST library. Of the 510 sequences determined, 268 (52.9%) were unique. Of these, 14 appeared to encode alpha- and 111 beta-keratins. Within the beta-keratins, we identified five groups based on nucleotide sequence comparisons. Of these, one contained the bulk of beta-keratins, with 103 EST members. The mRNAs within this major group, together with two singlets, encoded cysteine-proline-serine-rich proteins of 10-14 kDa (Ge-cprp). One of the smaller groups of transcripts encoded slightly larger glycine-proline-serine-rich proteins, of 14-19 kDa (Ge-gprp). The remaining group consisted of smaller (9 kDa) serine-tyrosine-rich beta-keratins (Ge-strp). Thus three classes could be distinguished by amino acid sequence alignment. Exact matches for some of the peptide sequences obtained from setal proteins by ms/ms sequencing occur within several of these clones. Most of the beta-keratins were basic and contained a core-box region of two beta-strand sequences, with high homology to core-boxes present in avian scale and feather beta-keratins. Core-boxes are beta-folded regions that are likely responsible for polymerization into the beta-keratin filaments. The two deduced alpha-keratins of 52.7 kDa are both acidic, and contain the typical central rod region with some homology to mammalian and avian alpha-keratins, with variable N- and C-terminal regions. Basic beta-keratins and acidic alpha-keratins may interact electrostatically to form the resistant corneous material of setae. (c) 2008 Wiley-Liss, Inc.

  8. Clinical decision - making review on magnetic attachments versus mechanical attachments in dental prosthetics

    Directory of Open Access Journals (Sweden)

    Francesca Fabiano

    2017-11-01

    Full Text Available Background Conventional dentures in edentulous patients show some limitations due to the lack of retention, support and stability thus resulting in difficulty to chew. The modern implantology allows to use different implant overdentures and different attachment systems. The selection of the attachment by practitioners is mainly influenced by the clinical experience or technical preferences. Aims The aim of the present review is to provide an adequate background to the clinicians, in order to select the prosthetic attachments according to the current literature. The mechanical attachments have been compared to the magnetic devices, with the aim to guide the decision of the practitioners. Methods Articles topics selection was based on the use of magnetic attachments in dentistry and the comparison between them and mechanical connectors. The databases used were PubMed/MEDLINE, Google Scholar and ISI Web of Science. A critical evaluation of the selected paper has been made to choose the ones that matched the inclusion criteria. Results Nowadays, few studies have compared different attachments in a manner useful for clinical decision-making. The main problem limiting long-term durability of magnetic attachments in the oral fluid is the poor corrosion resistance of permanent magnets and the consequent leaching of cytotoxic ions. Conclusion Magnetic attachments in comparison with other attaching systems can be useful in patients with special needs, in patients with limited interocclusal space, or in patients with neuromuscular limitations, thanks to the automatic reseating properties. However, it’s important to highlight that the mechanical attachments still represent the best choice in common conditions requiring dental prostheses.

  9. Mandibular implant-supported overdentures: attachment systems, and number and locations of implants--Part I.

    Science.gov (United States)

    Warreth, Abdulhadi; Alkadhimi, Aslam Fadel; Sultan, Ahmed; Byrne, Caroline; Woods, Edel

    2015-01-01

    The use of dental implants in replacing missing teeth is an integral part of restorative dental treatment. Use of conventional complete dentures is associated with several problems such as lack of denture stability, support and retention. However, when mandibular complete dentures were used with two or more implants, an improvement in the patients' psychological and social well-being could be seen. There is general consensus that removable implant-supported overdentures (RISOs) with two implants should be considered as the first-choice standard of care for an edentulous mandible. This treatment option necessitates the use of attachment systems that connect the complete denture to the implant. Nevertheless, each attachment system has its inherent advantages and disadvantages, which should be considered when choosing a system. The first part of this article provides an overview on options available to restore the mandibular edentulous arch with dental implants. Different types of attachment systems, their features and drawbacks are also reviewed.

  10. Examining antecedents of infant attachment security with mothers and fathers: An ecological systems perspective.

    Science.gov (United States)

    Lickenbrock, Diane M; Braungart-Rieker, Julia M

    2015-05-01

    Taking an ecological systems perspective, early parent-child relationships can be affected by interactions between systems where some are more proximally linked to the child than others. Socioeconomic status, a distal factor, is associated with social functioning during childhood, but research on its association with functioning during infancy, particularly attachment, is scant and inconsistent. Moreover, it is not clear how distal factors affect infant functioning. Other systems such as marital adjustment and parenting may moderate or mediate relations between distal factors and infant attachment. The current longitudinal study (n=135) examined the role of various systems - parental resources, marital functioning, parental sensitivity and involvement - in early infancy (3-, 5-, 7-months) on infant-mother (12-months) and infant-father (14-months) attachment security. Findings supported moderating processes but in different ways for infant-mother versus infant-father dyads. Implications for future studies and interventions are discussed. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Effect of 12-Day Spaceflight on Brain of Thick-Toed Geckos

    Science.gov (United States)

    Proshchina, A. E.; Karlamova, A. S.; Barabanovet, V. M.; Godovalova, O. S.; Guilimova, V. I.; Krivova, Y. S.; Makarov, A. N.; Nikitin, V. B.; Savelieva, E. S.; Saveliev, S. V.

    2008-06-01

    In the frames of Russian-American joint space experiment onboard Foton-M3 satellite there was undertaken a study of spaceflight influence on brain of the thick-toed gecko (Pachydactylus turneri Gray, 1864). Serial brain sections were stained according to Nissl and also the immunohistochemical method with antibodies to NGF-receptor (p75NGFR), CD95 (also known as Fas and APO-1), glial fibrillary acidic protein (GFAP) and transferrin-receptor (CD71). Detailed examination of the sections of rhombencephalon revealed cytological changes in the neuron bodies of vestibular nuclei inside the flight group. Immunohistochemicaly we found the increase density of CD95 and p75NGFR and decrease of GFAP expression in medial cortex and epithalamus in flight group compared both control.

  12. Sociosexual investigation in sexually experienced, hormonally manipulated male leopard geckos: relation with phosphorylated DARPP-32 in dopaminergic pathways.

    Science.gov (United States)

    Huang, Victoria; Hemmings, Hugh C; Crews, David

    2014-12-01

    Dopaminergic activity is both associated with sociosexual exposure and modulated by sexual experience and hormonal state across vertebrate taxa. Mature leopard geckos, a reptile with temperature-dependent sex determination, have dopaminoceptive nuclei that are influenced by their embryonic environment and sensitive to adult hormonal manipulation. In this study, we exposed hormonally manipulated male leopard geckos from different incubation temperatures to conspecifics and measured their sociosexual investigation, as well as phosphorylated DARPP-32 at Threonine 34 (pDARPP-32) immunoreactivity as a marker for D1 dopamine receptor activity in the nucleus accumbens, striatum, and preoptic area. Social investigation time by males of different incubation temperatures was modulated in opposite directions by exogenous androgen treatment. Males exposed to novel stimuli spent a greater proportion of time investigating females of different incubation temperatures. The time spent investigating females was positively correlated to pDARPP-32 immunoreactivity in the preoptic area. This is the first study quantifying pDARPP-32 in a lizard species, and suggests the protein as a potential marker to measure differences in the dopaminergic pathway in a social setting with consideration of embryonic environment and hormonal state. © 2014 Wiley Periodicals, Inc.

  13. God attachment, mother attachment, and father attachment in early and middle adolescence.

    Science.gov (United States)

    Sim, Tick Ngee; Yow, Amanda Shixian

    2011-06-01

    The present study examined the interplay of attachment to God, attachment to mother, and attachment to father with respect to adjustment (hope, self-esteem, depression) for 130 early and 106 middle adolescents in Singapore. Results showed that the parental attachments were generally linked (in expected directions) to adjustment. God attachment, however, had unique results. At the bivariate level, God attachment was only linked to early adolescents' self-esteem. When considered together with parental attachments (including interactions), God attachment did not emerge as the key moderator in attachment interactions and yielded some unexpected results (e.g., being positively linked to depression). These results are discussed viz-a-viz the secure base and safe haven functions that God and parental attachments may play during adolescence.

  14. Changes in androgen receptor mRNA expression in the forebrain and oviduct during the reproductive cycle of female leopard geckos, Eublepharis macularius.

    Science.gov (United States)

    Rhen, Turk; Sakata, Jon T; Woolley, Sarah; Porter, Raymond; Crews, David

    2003-06-01

    Successful reproduction requires the coordination of reproductive physiology with behavior. The neural correlates of reproductive behavior have been elucidated in a variety of amphibians, mammals, and birds but relatively few studies have examined reptiles. Here we investigate differences in androgen receptor (AR) mRNA expression in the forebrain and oviduct between previtellogenic and late vitellogenic female leopard geckos, Eublepharis macularius. Plasma concentrations of testosterone (T) are low when females are previtellogenic and sexually unreceptive but increase dramatically during late vitellogenesis when females are receptive. In addition, receptivity can be induced by treatment with exogenous T. The relative abundance of AR-mRNA across various nuclei was greater in late vitellogenic than in previtellogenic females. This general pattern was observed in the medial preoptic area, anterior hypothalamus, external nucleus of the amygdala, dorsolateral aspect of the ventromedial hypothalamus, lateral septum, and periventricular hypothalamus. There were also clear differences in AR-mRNA expression among these nuclei. The pattern of gene expression observed in the brain was reversed within stromal cells of the oviduct where expression of AR-mRNA decreased from the previtellogenic stage to the late vitellogenic stage. Overall, these data demonstrate that T concentration in the plasma, abundance of AR-mRNA in the brain and oviduct, and sexual behavior change coordinately during the reproductive cycle of female leopard geckos. Although the function of AR in the female leopard gecko is not yet clear, our results are in accord with growing evidence that androgens regulate numerous aspects of female physiology and behavior in vertebrates.

  15. Neural response during the activation of the attachment system in patients with borderline personality disorder: An fMRI study

    Directory of Open Access Journals (Sweden)

    Anna Buchheim

    2016-08-01

    Full Text Available Individuals with borderline personality disorder (BPD are characterized by emotional instability, impaired emotion regulation and unresolved attachment patterns associated with abusive childhood experiences. We investigated the neural response during the activation of the attachment system in BPD patients compared to healthy controls using functional magnetic resonance imaging. Eleven female patients with BPD without posttraumatic stress disorder and seventeen healthy female controls matched for age and education were telling stories in the scanner in response to the Adult Attachment Projective Picture System, an eight-picture set assessment of adult attachment. The picture set includes theoretically-derived attachment scenes, such as separation, death, threat and potential abuse. The picture presentation order is designed to gradually increase the activation of the attachment system. Each picture stimulus was presented for two minutes. Analyses examine group differences in attachment classifications and neural activation patterns over the course of the task. Unresolved attachment was associated with increasing amygdala activation over the course of the attachment task in patients as well as controls. Unresolved controls, but not patients, showed activation in the right dorsolateral prefrontal cortex and the rostral cingulate zone. We interpret this as a neural signature of BPD patients’ inability to exert top-down control under conditions of attachment distress. These findings point to possible neural mechanisms for underlying affective dysregulation in BPD in the context of attachment trauma and fear.

  16. Cone visual pigments are present in gecko rod cells.

    Science.gov (United States)

    Kojima, D; Okano, T; Fukada, Y; Shichida, Y; Yoshizawa, T; Ebrey, T G

    1992-08-01

    The Tokay gecko (Gekko gekko), a nocturnal lizard, has two kinds of visual pigments, P467 and P521. In spite of the pure-rod morphology of the photoreceptor cells, the biochemical properties of P521 and P467 resemble those of iodopsin (the chicken red-sensitive cone visual pigment) and rhodopsin, respectively. We have found that the amino acid sequence of P521 deduced from the cDNA was very similar to that of iodopsin. In addition, P467 has the highest homology with the chicken green-sensitive cone visual pigment, although it also has a relatively high homology with rhodopsins. These results give additional strength to the transmutation theory of Walls [Walls, G. L. (1934) Am. J. Ophthalmol. 17, 892-915], who proposed that the rod-shaped photoreceptor cells of lizards have been derived from ancestral cone-like photoreceptors. Apparently amino acid sequences of visual pigments are less changeable than the morphology of the photoreceptor cells in the course of evolution.

  17. Present diversity of Galápagos leaf-toed geckos (Phyllodactylidae: Phyllodactylus) stems from three independent colonization events.

    Science.gov (United States)

    Torres-Carvajal, Omar; Rodríguez-Guerra, Andrea; Chaves, Jaime A

    2016-10-01

    We re-examined the biogeography of the leaf-toed geckos (Phyllodactylus) endemic to the Galápagos Islands by analyzing for the first time samples of P. gilberti, a species endemic to Wolf island, in a phylogenetic framework. Our aim was to test the three-colonizations scenario previously proposed for these lizards and estimate the age of each colonization event. To achieve this we estimated simultaneously a species tree and divergence times with Bayesian methods. Our results supported the three-colonizations scenario. Similar to a previous hypothesis, the species tree obtained here showed that most species of Phyllodactylus are nested in a single clade with an age between 5.49 and 13.8Ma, whereas a second independent colonization corresponding to P. darwini from San Cristóbal island occurred 3.03Ma ago. The species from Wolf island, P. gilberti, stems from a more recent colonization event (0.69Ma). Thus, present diversity of Galápagos leaf-toed geckos stems from three independent, asynchronous colonization events. As with other Galápagos organisms, the Pacific coast of South America seems to be the source for the founders of P. gilberti. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. Gecko-inspired bidirectional double-sided adhesives.

    Science.gov (United States)

    Wang, Zhengzhi; Gu, Ping; Wu, Xiaoping

    2014-05-14

    A new concept of gecko-inspired double-sided adhesives (DSAs) is presented. The DSAs, constructed by dual-angled (i.e. angled base and angled tip) micro-pillars on both sides of the backplane substrate, are fabricated by combinations of angled etching, mould replication, tip modification, and curing bonding. Two types of DSA, symmetric and antisymmetric (i.e. pillars are patterned symmetrically or antisymmetrically relative to the backplane), are fabricated and studied in comparison with the single-sided adhesive (SSA) counterparts through both non-conformal and conformal tests. Results indicate that the DSAs show controllable and bidirectional adhesion. Combination of the two pillar-layers can either amplify (for the antisymmetric DSA, providing a remarkable and durable adhesion capacity of 25.8 ± 2.8 N cm⁻² and a high anisotropy ratio of ∼8) or counteract (for the symmetric DSA, generating almost isotropic adhesion) the adhesion capacity and anisotropic level of one SSA (capacity of 16.2 ± 1.7 N cm⁻² and anisotropy ratio of ∼6). We demonstrate that these two DSAs can be utilized as a facile fastener for two individual objects and a small-scale delivery setup, respectively, complementing the functionality of the commonly studied SSA. As such, the double-sided patterning is believed to be a new branch in the further development of biomimetic dry adhesives.

  19. Fitness networks for real world systems via modified preferential attachment

    Science.gov (United States)

    Shang, Ke-ke; Small, Michael; Yan, Wei-sheng

    2017-05-01

    Complex networks are virtually ubiquitous, and the Barabási and Albert model (BA model) has became an acknowledged standard for the modelling of these systems. The so-called BA model is a kind of preferential attachment growth model based on the intuitive premise that popularity is attractive. However, preferential attachment alone is insufficient to describe the diversity of complex networks observed in the real world. In this paper we first use the accuracy of a link prediction method, as a metric for network fitness. The link prediction method predicts the occurrence of links consistent with preferential attachment, the performance of this link prediction scheme is then a natural measure of the ;preferential-attachment-likeness; of a given network. We then propose several modification methods and modified BA models to construct networks which more accurately describe the fitness properties of real networks. We find that all features assortativity, degree distribution and rich-club formation can play significant roles for the network construction and eventual structure. Moreover, link sparsity and the size of a network are key factors for network reconstruction. In addition, we find that the structure of the network which is limited by geographic location (nodes are embedded in a Euclidean space and connectivity is correlated with distances) differs from other typical networks. In social networks, we observe that the high school contact network has similar structure as the friends network and so we speculate that the contact behaviours can reflect real friendships.

  20. Differences induced by incubation temperature, versus androgen manipulation, in male leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Huang, Victoria; Crews, David

    2012-08-20

    A fundamental tenet of sexual selection is that in sexually dimorphic traits, there is variation within a sex. In leopard geckos (Eublepharis macularius), a species with temperature-dependent sex determination, embryonic temperature contributes both to sex determination and polymorphisms within each sex. In this study we report that males from different incubation temperatures, one hitherto untested, exhibit significant differences in behavior even when castrated. Further, treatment with dihydrotestosterone increases scent marking, a territorial behavior. This supports previous results indicating that temperature has a direct organizing action on brain and sociosexual behavior independent of gonadal hormones. Copyright © 2012 Elsevier Inc. All rights reserved.

  1. The first cytogenetic description of Euleptes europaea (Gené, 1839 from Northern Sardinia reveals the highest diploid chromosome number among sphaerodactylid geckos (Sphaerodactylidae, Squamata

    Directory of Open Access Journals (Sweden)

    Ekaterina Gornung

    2013-06-01

    Full Text Available The karyotype of a sphaerodactylid gecko Euleptes europaea (Gené, 1839 was assembled for the first time in this species. It is made of 2n = 42 gradually decreasing in size chromosomes, the highest chromosome number so far acknowledged in the family Sphaerodactylidae. The second chromosome pair of the karyotype appears slightly heteromorphic in the male individual. Accordingly, FISH with a telomeric probe revealed an uneven distribution of telomeric repeats on the two homologues of this pair, which may be indicative of an XY sex-determination system in the species, to be further investigated.

  2. Mechanical testing of a FW panel attachment system for ITER

    International Nuclear Information System (INIS)

    Oliva, Vladislav; Vaclavik, Jaroslav; Materna, Ales; Lorenzetto, Patrick; Furmanek, Andreas

    2009-01-01

    An objective of experiments and finite element simulations was to check the stiffness, the strength and the fatigue resistance of the attachment of the First Wall panels onto a shield block of blanket modules according to the ITER 2001 design. The panel has a poloidal key at the rear side (in so-called option A with the rear access bolting) and it is attached by means of special studs located on a key-way in the shield block. Special device for a test of stud tensile pre-load relaxation during a thermal cycling was developed. True-to-scale panels, the shield block mock-up and simplified studs were fabricated and the assembly was loaded alternatively by radial moment, poloidal force or poloidal moment simulating the loading during off-normal plasma operations. Thermal cycling led to an acceptable stud pre-load relaxation. Mechanical cycling caused neither the pre-load relaxation nor the loss of the contact in the key-way nor a damage of the attachment system. The combination of poloidal moment and radial force during vertical displacement events (VDEs) seems to be a most dangerous case because it could lead to the loss of the key-key-way contact.

  3. Bacterial production and growth rate estimation from [3H]thymidine incorporation for attached and free-living bacteria in aquatic systems

    International Nuclear Information System (INIS)

    Iriberri, J.; Unanue, M.; Ayo, B.; Barcina, I.; Egea, L.

    1990-01-01

    Production and specific growth rates of attached and free-living bacteria were estimated in an oligotrophic marine system, La Salvaje Beach, Vizcaya, Spain, and in a freshwater system having a higher nutrient concentration, Butron River, Vizcaya, Spain. Production was calculated from [methyl- 3 H]thymidine incorporation by estimating specific conversion factors (cells or micrograms of C produced per mole of thymidine incorporated) for attached and free-living bacteria, respectively, in each system. Conversion factors were not statistically different between attached and free-living bacteria: 6.812 x 10 11 and 8.678 x 10 11 μg of C mol -1 for free-living and attached bacteria in the freshwater system, and 1.276 x 10 11 and 1.354 x 10 11 μg of C mol -1 for free-living and attached bacteria in the marine system. Therefore, use of a unique conversion factor for the mixed bacterial population is well founded. However, conversion factors were higher in the freshwater system than in the marine system. This could be due to the different tropic conditions of the two systems. Free-living bacteria contributed the most to production in the two systems (85% in the marine system and 67% in the freshwater system) because of their greater contribution to total biomass. Specific growth rates calculated from production data and biomass data were similar for attached and free-living bacteria

  4. Parents' attachment histories and children's externalizing and internalizing behaviors: exploring family systems models of linkage.

    Science.gov (United States)

    Cowan, P A; Cowan, C P; Cohn, D A; Pearson, J L

    1996-02-01

    Twenty-seven mothers and 27 fathers were given the Adult Attachment Interview (M. Main & R. Goldwyn, in press) when their children were 3.5 years old. Continuous ratings of narrative coherence, probable experience quality (parents perceived as loving), and state of mind (current anger at parents) were entered as latent variables in partial least squares structural equation models that included observational measures of marital quality and parenting style. Models that include fathers' attachment histories predicted more variance in kindergarten teachers' descriptions of children's externalizing behavior, whereas models that include mothers' attachment histories predicted more variance in children's internalizing behavior. Marital data added predictive power to the equations. Discussion is focused on the importance of integrating attachment and family systems approaches, and of parents' gender and marital quality, in understanding specific links between parents' attachment histories and their young children's externalizing and internalizing behaviors.

  5. Mechanics of load-drag-unload contact cleaning of gecko-inspired fibrillar adhesives.

    Science.gov (United States)

    Abusomwan, Uyiosa A; Sitti, Metin

    2014-10-14

    Contact self-cleaning of gecko-inspired synthetic adhesives with mushroom-shaped tips has been demonstrated recently using load-drag-unload cleaning procedures similar to that of the natural animal. However, the underlying mechanics of contact cleaning has yet to be fully understood. In this work, we present a detailed experiment of contact self-cleaning that shows that rolling is the dominant mechanism of cleaning for spherical microparticle contaminants, during the load-drag-unload procedure. We also study the effect of dragging rate and normal load on the particle rolling friction. A model of spherical particle rolling on an elastomer fibrillar adhesive interface is developed and agrees well with the experimental results. This study takes us closer to determining design parameters for achieving self-cleaning fibrillar adhesives.

  6. Exact free vibration of multi-step Timoshenko beam system with several attachments

    Science.gov (United States)

    Farghaly, S. H.; El-Sayed, T. A.

    2016-05-01

    This paper deals with the analysis of the natural frequencies, mode shapes of an axially loaded multi-step Timoshenko beam combined system carrying several attachments. The influence of system design and the proposed sub-system non-dimensional parameters on the combined system characteristics are the major part of this investigation. The effect of material properties, rotary inertia and shear deformation of the beam system for each span are included. The end masses are elastically supported against rotation and translation at an offset point from the point of attachment. A sub-system having two degrees of freedom is located at the beam ends and at any of the intermediate stations and acts as a support and/or a suspension. The boundary conditions of the ordinary differential equation governing the lateral deflections and slope due to bending of the beam system including the shear force term, due to the sub-system, have been formulated. Exact global coefficient matrices for the combined modal frequencies, the modal shape and for the discrete sub-system have been derived. Based on these formulae, detailed parametric studies of the combined system are carried out. The applied mathematical model is valid for wide range of applications especially in mechanical, naval and structural engineering fields.

  7. Molecular phylogenetics and species delimitation of leaf-toed geckos (Phyllodactylidae: Phyllodactylus) throughout the Mexican tropical dry forest.

    Science.gov (United States)

    Blair, Christopher; Méndez de la Cruz, Fausto R; Law, Christopher; Murphy, Robert W

    2015-03-01

    Methods and approaches for accurate species delimitation continue to be a highly controversial subject in the systematics community. Inaccurate assessment of species' limits precludes accurate inference of historical evolutionary processes. Recent evidence suggests that multilocus coalescent methods show promise in delimiting species in cryptic clades. We combine multilocus sequence data with coalescence-based phylogenetics in a hypothesis-testing framework to assess species limits and elucidate the timing of diversification in leaf-toed geckos (Phyllodactylus) of Mexico's dry forests. Tropical deciduous forests (TDF) of the Neotropics are among the planet's most diverse ecosystems. However, in comparison to moist tropical forests, little is known about the mode and tempo of biotic evolution throughout this threatened biome. We find increased speciation and substantial, cryptic molecular diversity originating following the formation of Mexican TDF 30-20million years ago due to orogenesis of the Sierra Madre Occidental and Mexican Volcanic Belt. Phylogenetic results suggest that the Mexican Volcanic Belt, the Rio Fuerte, and Isthmus of Tehuantepec may be important biogeographic barriers. Single- and multilocus coalescent analyses suggest that nearly every sampling locality may be a distinct species. These results suggest unprecedented levels of diversity, a complex evolutionary history, and that the formation and expansion of TDF vegetation in the Miocene may have influenced subsequent cladogenesis of leaf-toed geckos throughout western Mexico. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. The gecko visual pigment: the anion hypsochromic effect.

    Science.gov (United States)

    Crescitelli, F; Karvaly, B

    1991-01-01

    The 521-pigment in the retina of the Tokay gecko (Gekko gekko) readily responds to particular physical and chemical changes in its environment. When solubilized in chloride deficient state the addition of Class I anions (Cl-, Br-) induces a bathochromic shift of the absorption spectrum. Class II anions (NO3-, IO3-, N3-, OCN-, SCN-, SeCN-, N(CN)2-), which exhibit ambidental properties, cause an hypsochromic shift. Class III anions (F-, I-, NO2-, CN-, AsO3-, SO2(4-), S2O2(3-) have no spectral effect on the 521-pigment. Cations appear to have no influence on the pigment absorption and Class I anions prevent or reverse the hypsochromic shift caused by Class II anions. It is suggested that the spectral displacements reflect specific changes in the opsin conformation, which alter the immediate (dipolar) environment of the retinal chromophore. The protein conformation seems to promote excited-state processes most in the native 521-pigment state and least in the presence of Class II anions. This in turn suggests that the photosensitivity of the 521-pigment is controlled by the excited rather than by the ground-state properties of the pigment.

  9. Chloride effect on the early photolysis intermediates of a gecko cone-type visual pigment.

    Science.gov (United States)

    Lewis, J W; Liang, J; Ebrey, T G; Sheves, M; Kliger, D S

    1995-05-02

    Nanosecond laser photolysis measurements were conducted on the cone-type visual pigment P521 in digitonin extracts of Tokay gecko (Gekko gekko) retina containing physiological chloride ion levels and also on samples which had been chloride depleted or which contained high levels (4 M) of chloride. Absorbance difference spectra were recorded at a sequence of time delays from 30 ns to 60 microseconds following excitation with a pulse of either 532- or 477-nm actinic light. Global analysis showed the kinetic decay data for gecko pigment P521 to be best fit by two exponential processes under all chloride conditions. The initial photoproduct detected had a broad spectrum characteristic of an equilibrated mixture of a Batho P521 intermediate with its blue-shifted intermediate (BSI P521) decay product. The first exponential process was assigned to the decay of this mixture to the Lumi P521 intermediate. The second exponential process was identified as the decay of Lumi P521 to Meta I P521. The initial photoproduct's spectrum exhibited a strong dependence on chloride concentration, indicating that chloride affects the composition of the equilibrated mixture of Batho P521 and BSI P521. These results suggest that the affinity for chloride is reduced approximately 5-fold in the Batho P521 intermediate and approximately 50-fold in the BSI P521 intermediate. Chloride concentration also affects the apparent decay rate of the equilibrated mixture. When the apparent decay rate is corrected for the composition of the equilibrated mixture, a relatively invariant microscopic rate constant is obtained for BSI decay (k = 1/55 ns-1).(ABSTRACT TRUNCATED AT 250 WORDS)

  10. Development of a New Delivery and Attachment System for Tagging Large Cetaceans

    National Research Council Canada - National Science Library

    Harvey, James

    1997-01-01

    .... We developed a new method of delivering tags for placement on large whales. Sea lions were trained to carry a harness and attached camera system along with carrying a suction-cup tag in a mouth piece...

  11. Overdenture locator attachments for atrophic mandible

    Directory of Open Access Journals (Sweden)

    Neerja Mahajan

    2013-01-01

    Full Text Available Implant-supported overdentures provide a good opportunity for dentists to improve oral health and quality-of-life of patients. Atrophic mandible poses a significant challenge to successful oral rehabilitation with dental implants. In this article, the fabrication of lower overdenture by two narrow platform implants is described with dual retentive, resilient, self-locating locator attachment system. The locator attachment system has the lowest profile in comparison with the ball and bar attachments and is versatile up to 40΀ of divergence between two implants. By using locators as attachments, we can meet functional, economic and social expectation of patients with ease and satisfaction.

  12. Next Steps in Attachment Theory.

    Science.gov (United States)

    Bell, David C

    2012-12-01

    Thanks to the phenomenal success of attachment theory, great progress has been made in understanding child and adult relationships. The success of attachment theory opens the way to new research directions that can extend its successes even further. In particular, more work on the fundamental nature of attachment that respects recent biological research is important, as is concentrated effort on the related caregiving system.

  13. Next Steps in Attachment Theory

    OpenAIRE

    Bell, David C.

    2012-01-01

    Thanks to the phenomenal success of attachment theory, great progress has been made in understanding child and adult relationships. The success of attachment theory opens the way to new research directions that can extend its successes even further. In particular, more work on the fundamental nature of attachment that respects recent biological research is important, as is concentrated effort on the related caregiving system.

  14. Sex-specific trade-offs and compensatory mechanisms: bite force and sprint speed pose conflicting demands on the design of geckos (Hemidactylus frenatus).

    Science.gov (United States)

    Cameron, S F; Wynn, M L; Wilson, R S

    2013-10-15

    One of the more intuitive viability costs that can result from the possession of exaggerated sexually selected traits is increased predation pressure as a result of reduced locomotor capacity. Despite mixed empirical support for such locomotor costs, recent studies suggest that such costs may be masked by compensatory traits that effectively offset any detrimental effects. In this study, we provide a comprehensive assessment of the locomotor costs associated with improved male-male competitive ability by simultaneously testing for locomotor trade-offs and potential compensatory mechanisms in territorial male and non-territorial female geckos. Fighting capacity and escape performance of male Asian house geckos (Hemidactylus frenatus) are likely to pose conflicting demands on the optimum phenotype for each task. Highly territorial and aggressive males may require greater investment in head size/strength but such an enhancement may affect overall escape performance. Among male geckos, we found that greater biting capacity because of larger head size was associated with reduced sprint performance; this trade-off was further exacerbated when sprinting on an incline. Females, however, showed no evidence of this trade-off on either flat or inclined surfaces. The sex specificity of this trade-off suggests that the sexes differ in their optimal strategies for dealing with the conflicting requirements of bite force and sprint speed. Unlike males, female H. frenatus had a positive association between hind-limb length and head size, suggesting that they have utilised a compensatory mechanism to alleviate the possible locomotor costs of larger head sizes. It appears that there is greater selection on traits that improve fighting ability (bite force) for males, but it is viability traits (sprint speed) that appear to be of greater importance for females. Our results emphasise that only by examining both functional trade-offs and potential compensatory mechanisms is it possible

  15. Sexuality examined through the lens of attachment theory: attachment, caregiving, and sexual satisfaction.

    Science.gov (United States)

    Péloquin, Katherine; Brassard, Audrey; Lafontaine, Marie-France; Shaver, Phillip R

    2014-01-01

    Attachment researchers have proposed that the attachment, caregiving, and sexual behavioral systems are interrelated in adult love relationships (Mikulincer & Shaver, 2007 ). This study examined whether aspects of partners' caregiving (proximity, sensitivity, control, compulsive caregiving) mediated the association between their attachment insecurities (anxiety and avoidance) and each other's sexual satisfaction in two samples of committed couples (Study 1: 126 cohabiting or married couples from the general community; Study 2: 55 clinically distressed couples). Partners completed the Experiences in Close Relationships measure (Brennan, Clark, & Shaver, 1998 ), the Caregiving Questionnaire (Kunce & Shaver, 1994 ), and the Global Measure of Sexual Satisfaction (Lawrance & Byers, 1998 ). Path analyses based on the actor-partner interdependence model (APIM) revealed that caregiving proximity mediated the association between low attachment avoidance and partners' sexual satisfaction in distressed and nondistressed couples. Sensitivity mediated this association in nondistressed couples only. Control mediated the association between men's insecurities (attachment-related avoidance and anxiety) and their partners' low sexual satisfaction in nondistressed couples. Attachment anxiety predicted compulsive caregiving, but this caregiving dimension was not a significant mediator. These results are discussed in light of attachment theory and their implications for treating distressed couples.

  16. Differentiation of sex chromosomes and karyotypic evolution in the eye-lid geckos (Squamata: Gekkota: Eublepharidae), a group with different modes of sex determination

    Czech Academy of Sciences Publication Activity Database

    Pokorná, M.; Rábová, Marie; Ráb, Petr; Kratochvíl, L.

    2010-01-01

    Roč. 18, č. 6 (2010), s. 748-748 ISSN 0967-3849. [19th International Colloquium on animal cytogenetics and gene mapping. 06.06.-09.06.2010, Krakow] Institutional research plan: CEZ:AV0Z50450515 Keywords : sex chromosomes * karyotypic evolution * eye-lid geckos Subject RIV: EB - Genetics ; Molecular Biology

  17. Stooped Nanohairs: Geometry-Controllable, Unidirectional, Reversible, and Robust Gecko-like Dry Adhesive

    KAUST Repository

    Kim, Tae-il

    2009-06-12

    A study was conducted to demonstrate a simple method for fabricating stopped high-aspect-ratio (AR) nanohairs of polyurethane acrylate (PUA) material that utilized replica molding and post-electron-beam irradiation. The method offered a facile route to prepare angled polymer nanohairs without multistep processes or surface treatment. It was demonstrated that the PUA material was molded into a geometry controlled and high-density nanochair surface with an AR of up to 10 without facing self-matting problem, due to its favorable mechanical properties. The as-formed hairy structures also allowed for structural transformation into directional and angled nanohairs, while maintaining better adhesion capability. The nanohair surface also showed significant unidirectional adhesion properties and a higher shear adhesion due to its structural similarity to natural gecko foot hairs.

  18. Organization of the auditory brainstem in a lizard, Gekko gecko. I. Auditory nerve, cochlear nuclei, and superior olivary nuclei.

    Science.gov (United States)

    Tang, Yezhong; Christensen-Dalsgaard, Jakob; Carr, Catherine E

    2012-06-01

    We used tract tracing to reveal the connections of the auditory brainstem in the Tokay gecko (Gekko gecko). The auditory nerve has two divisions, a rostroventrally directed projection of mid- to high best-frequency fibers to the nucleus angularis (NA) and a more dorsal and caudal projection of low to middle best-frequency fibers that bifurcate to project to both the NA and the nucleus magnocellularis (NM). The projection to NM formed large somatic terminals and bouton terminals. NM projected bilaterally to the second-order nucleus laminaris (NL), such that the ipsilateral projection innervated the dorsal NL neuropil, whereas the contralateral projection crossed the midline and innervated the ventral dendrites of NL neurons. Neurons in NL were generally bitufted, with dorsoventrally oriented dendrites. NL projected to the contralateral torus semicircularis and to the contralateral ventral superior olive (SOv). NA projected to ipsilateral dorsal superior olive (SOd), sent a major projection to the contralateral SOv, and projected to torus semicircularis. The SOd projected to the contralateral SOv, which projected back to the ipsilateral NM, NL, and NA. These results suggest homologous patterns of auditory connections in lizards and archosaurs but also different processing of low- and high-frequency information in the brainstem. Copyright © 2011 Wiley Periodicals, Inc.

  19. Antimicrobial and Herbal Drug Resistance in Enteric Bacteria Isolated from Faecal Droppings of Common House Lizard/Gecko (Hemidactylus frenatus

    Directory of Open Access Journals (Sweden)

    Bhoj R. Singh

    2013-01-01

    Full Text Available From 194 faecal dropping samples of common house geckos collected from offices (60, houses (88, integrated farm units (IFS,18 and hostels, guest houses, and dining rooms of different canteen/mess (HGM, 28, 326 bacterial isolates of enteric bacteria belonging to 17 genera and 34 species were detected. Escherichia coli were the most frequently (39 isolated followed by Citrobacter freundii (33, Klebsiella pneumonia (27, Salmonella indica (12, Enterobacter gergoviae (12, and Ent. agglomerans (11. Other important bacteria isolated from gecko droppings were Listonella damsela (2, Raoultella terrigena (3, S. salamae (2, S. houtenae (3, Edwardsiella tarda (4, Edwardsiella hoshinae (1, and Klebsiella oxytoca (2. Of the 223 isolates tested for antimicrobial drug sensitivity, 27 (12.1% had multiple drug resistance (MDR. None of the salmonellae or edwardsiellae had MDR however, MDR strains were significantly more common among Escherichia spp. (P=1.9×10-5 and isolates from IFS units (P=3.58×10-23. The most effective herbal drug, Ageratum conyzoides extract, inhibited growth of only 27.8% of strains tested followed by ethanolic extract of Zanthoxylum rhetsa (13.9%, eucalyptus oil (5.4%, patchouli oil (5.4%, lemongrass oil (3.6%, and sandalwood oil (3.1%, and Artemisia vulgaris essential oil (3.1%.

  20. Testing the island effect on phenotypic diversification: insights from the Hemidactylus geckos of the Socotra Archipelago

    Science.gov (United States)

    Garcia-Porta, Joan; Šmíd, Jiří; Sol, Daniel; Fasola, Mauro; Carranza, Salvador

    2016-04-01

    Island colonization is often assumed to trigger extreme levels of phenotypic diversification. Yet, empirical evidence suggests that it does not always so. In this study we test this hypothesis using a completely sampled mainland-island system, the arid clade of Hemidactylus, a group of geckos mainly distributed across Africa, Arabia and the Socotra Archipelago. To such purpose, we generated a new molecular phylogeny of the group on which we mapped body size and head proportions. We then explored whether island and continental taxa shared the same morphospace and differed in their disparities and tempos of evolution. Insular species produced the most extreme sizes of the radiation, involving accelerated rates of evolution and higher disparities compared with most (but not all) of the continental groups. In contrast, head proportions exhibited constant evolutionary rates across the radiation and similar disparities in islands compared with the continent. These results, although generally consistent with the notion that islands promote high morphological disparity, reveal at the same time a complex scenario in which different traits may experience different evolutionary patterns in the same mainland-island system and continental groups do not always present low levels of morphological diversification compared to insular groups.

  1. The oogenic cycle of the Caspian bent-toed gecko, Cyrtopodion caspium (Squamata: Gekkonidae in Iran

    Directory of Open Access Journals (Sweden)

    Vida Hojati

    2013-07-01

    Full Text Available The Caspian bent-toed gecko, Cyrtopodion caspium, is one of the commonest lizards in northern Iran. It is nocturnal, anthropophile and oviparous. In this study, the reproductive cycle of this species was studied by focusing on oogenesis, from April 5 to October 20, 2011. In total, 70 adult females were obtained from Mazandaran, one of the northern provinces of Iran where the climate is temperate. Ovaries were removed and processed for histological and morphometric studies. The results show that oocyte growth starts in late April and ends in August. Mating starts in spring, especially at the beginning of May, with oviposition occurring from late May to mid August. Females lay 1-2 eggs per clutch with the possibility of producing a secondary clutch later in the season. Maximum reproductive activity occurs in May and peaks in June. There was no significant difference between right and left side of reproductive system. With oogenesis occurring from April through July, C. caspium follows an oogenic cycle typical for temperate species.

  2. Immunolocalization of keratin-associated beta-proteins (beta-keratins) in pad lamellae of geckos suggest that glycine-cysteine-rich proteins contribute to their flexibility and adhesiveness.

    Science.gov (United States)

    Alibardi, Lorenzo

    2013-03-01

    The epidermis of digital pads in geckos comprises superficial microornamentation from the oberhautchen layer that form long setae allowing these lizards to climb vertical surfaces. The beta-layer is reduced in pad lamellae but persists up to the apical free margin. Setae are made of different proteins including keratin-associated beta-proteins, formerly indicated as beta-keratins. In order to identify specific setal proteins the present ultrastructural study on geckos pad lamellae analyzes the immunolocalization of three beta-proteins previously found in the epidermis and adhesive setae of the green anolis. A protein rich in glycine but poor in cysteine (HgG5-like) is absent or masked in gecko pad lamellae. Another protein rich in glycine and cysteine (HgGC3-like) is weakly present in setae, oberhautchen and beta-layer. A glycine and cysteine medium rich beta-protein (HgGC10-like) is present in the lower part of the beta-layer but is absent in the oberhautchen, setae, and mesos layer. The latter two proteins may form intermolecular bonds that contribute to the flexibility of the corneous material sustaining the setae. The pliable alpha-layer present beneath the thin beta-layer and in the hinge region of the pad lamellae also contains HgGC10-like proteins. Based on the possibility that some HgGC3-like or other cys-rich beta-proteins are charged in the setae it is suggested that their charges influence the mechanism of adhesion increasing the induction of dipoles on the substrate and enhancing attractive van der Waals forces. Copyright © 2013 Wiley Periodicals, Inc.

  3. Adolescents' multiple versus single primary attachment figures, reorganization of attachment hierarchy, and adjustments: the important people interview approach.

    Science.gov (United States)

    Umemura, Tomotaka; Lacinová, Lenka; Kraus, Jakub; Horská, Eliška; Pivodová, Lenka

    2018-04-20

    Using 212 adolescents from a central-European country (mean age = 14.02, SD = 2.05, ranged from 11 to 18 years; females = 54%) and a multi-informant method to measure adolescents' behavioral and emotional adjustments, the present study explored three aspects regarding the attachment hierarchy. (1) The three types of behavioral systems of Rosenthal and Kobak's important people interview (IPI) were initially validated using an exploratory factor analysis with a US sample. Using a confirmatory factor analysis with a Czech sample, we replicated these three behavioral systems: attachment bond, support seeking, and affiliation. (2) We found that adolescents who developed attachment bond to multiple primary attachment figures were likely to score lower on both teacher-rated and parent-rated internalizing problems compared to those who had a single primary attachment figure. These multiple primary attachment figures tended to be family members (not peers). (3) Early adolescents who placed parents low in their attachment hierarchy scored higher on self-reported negative affect and lower on self-reported positive affect compared to early adolescents who placed parents high. The present study highlights multiple (vs. single) primary attachment figures as a protective factor and the premature reorganization of attachment hierarchy as a risk factor for adolescents' emotional and affective adjustments.

  4. Patient satisfaction and dissatisfaction with mandibular two-implant overdentures using different attachment systems: 5-year outcomes.

    Science.gov (United States)

    Al-Zubeidi, Mohammed I; Alsabeeha, Nabeel H M; Thomson, W Murray; Payne, Alan G T

    2012-10-01

    Different attachment systems for mandibular two-implant overdentures could influence levels of patient satisfaction. Positive consensus of the majority of patients being satisfied does not preclude the possibility of dissatisfaction for some. To evaluate patient satisfaction and dissatisfaction before and after 5 years of wearing mandibular two implant overdentures using different attachment systems ; to determine the prognostic relevance of pretreatment complete denture complaints to treatment outcomes. A total of 106 edentulous participants enrolled in a clinical trial completed a preliminary self-report inventory of their original complete denture complaints.New complete maxillary dentures and mandibular two-implant overdentures were provided to each participant using one of six different attachment systems. Patient satisfaction was determined at pretreatment; at baseline with mandibular two-implant overdenture insertion; and then annually for 5 years, using visual analogue and Likert-type scales. Patient satisfaction with mandibular two-implant overdentures showed significant changes pre- to posttreatment(baseline) in all domains, but these were significant immediately and maintained without further significance for 5 years, other than pain with the overdenture. After 5 years, no significant differences were observed with all the attachment systems. Highly significant differences were found with some social and psychological aspects by the fifth year compared to baseline. Diagnostic and prognostic indicators from a pretreatment inventory identified 12 participants (13.5%) who were dissatisfied. These indicators revealed a maladaptive predisposition to mandibular two-implant overdentures. The provision of mandibular two-implant overdentures will, in the majority of patients, significantly enhance levels of patient satisfaction for 5 years, as compared to complete mandibular dentures, regardless of the attachment system. Careful evaluation of pretreatment

  5. GeckoFTL: Scalable Flash Translation Techniques For Very Large Flash Devices

    DEFF Research Database (Denmark)

    Dayan, Niv; Bonnet, Philippe; Idreos, Stratos

    2016-01-01

    The volume of metadata needed by a flash translation layer (FTL) is proportional to the storage capacity of a flash device. Ideally, this metadata should reside in the device's integrated RAM to enable fast access. However, as flash devices scale to terabytes, the necessary volume of metadata...... thereby harming performance and device lifetime. In this paper, we identify a key component of the metadata called the Page Validity Bitmap (PVB) as the bottleneck. PVB is used by the garbage-collectors of state-of-the-art FTLs to keep track of which physical pages in the device are invalid. PVB...... constitutes 95% of the FTL's RAM-resident metadata, and recovering PVB after power fails takes a significant proportion of the overall recovery time. To solve this problem, we propose a page-associative FTL called GeckoFTL, whose central innovation is replacing PVB with a new data structure called Logarithmic...

  6. Key innovations and island colonization as engines of evolutionary diversification: a comparative test with the Australasian diplodactyloid geckos.

    Science.gov (United States)

    Garcia-Porta, J; Ord, T J

    2013-12-01

    The acquisition of key innovations and the invasion of new areas constitute two major processes that facilitate ecological opportunity and subsequent evolutionary diversification. Using a major lizard radiation as a model, the Australasian diplodactyloid geckos, we explored the effects of two key innovations (adhesive toepads and a snake-like phenotype) and the invasion of new environments (island colonization) in promoting the evolution of phenotypic and species diversity. We found no evidence that toepads had significantly increased evolutionary diversification, which challenges the common assumption that the evolution of toepads has been responsible for the extensive radiation of geckos. In contrast, a snakelike phenotype was associated with increased rates of body size evolution and, to a lesser extent, species diversification. However, the clearest impact on evolutionary diversification has been the colonization of New Zealand and New Caledonia, which were associated with increased rates of both body size evolution and species diversification. This highlights that colonizing new environments can drive adaptive diversification in conjunction or independently of the evolution of a key innovation. Studies wishing to confirm the putative link between a key innovation and subsequent evolutionary diversification must therefore show that it has been the acquisition of an innovation specifically, not the colonization of new areas more generally, that has prompted diversification. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  7. Not all cells are equal: effects of temperature and sex on the size of different cell types in the Madagascar ground gecko Paroedura picta

    Directory of Open Access Journals (Sweden)

    Marcin Czarnoleski

    2017-08-01

    Full Text Available Cell size plays a role in evolutionary and phenotypically plastic changes in body size. To examine this role, we measured the sizes of seven cell types of geckos (Paroedura picta reared at three constant temperatures (24, 27, and 30°C. Our results show that the cell size varies according to the body size, sex and developmental temperature, but the pattern of this variance depends on the cell type. We identified three groups of cell types, and the cell sizes changed in a coordinated manner within each group. Larger geckos had larger erythrocytes, striated muscle cells and hepatocytes (our first cell group, but their renal proximal tubule cells and duodenal enterocytes (our second cell group, as well as tracheal chondrocytes and epithelial skin cells (our third cell group, were largely unrelated to the body size. For six cell types, we also measured the nuclei and found that larger cells had larger nuclei. The relative sizes of the nuclei were not invariant but varied in a complex manner with temperature and sex. In conclusion, we provide evidence suggesting that changes in cell size might be commonly involved in the origin of thermal and sexual differences in adult size. A recent theory predicts that smaller cells speed up metabolism but demand more energy for their maintenance; consequently, the cell size matches the metabolic demand and supply, which in ectotherms, largely depends on the thermal conditions. The complex thermal dependency of cell size in geckos suggests that further advancements in understanding the adaptive value of cell size requires the consideration of tissue-specific demand/supply conditions.

  8. Time-varying motor control of autotomized leopard gecko tails: multiple inputs and behavioral modulation.

    Science.gov (United States)

    Higham, Timothy E; Russell, Anthony P

    2012-02-01

    Autotomy (voluntary loss of an appendage) is common among diverse groups of vertebrates and invertebrates, and much attention has been given to ecological and developmental aspects of tail autotomy in lizards. Although most studies have focused on the ramifications for the lizard (behavior, biomechanics, energetics, etc.), the tail itself can exhibit interesting behaviors once segregated from the body. For example, recent work highlighted the ability of leopard gecko tails to jump and flip, in addition to being able to swing back and forth. Little is known, however, about the control mechanisms underlying these movements. Using electromyography, we examined the time-varying in vivo motor patterns at four sites (two proximal and two distal) in the tail of the leopard gecko, Eublepharis macularius, following autotomy. Using these data we tested the hypothesis that the disparity in movements results simply from overlapping pattern generators within the tail. We found that burst duration, but not cycle duration, of the rhythmic swings reached a plateau at approximately 150 s following autotomy. This is likely because of physiological changes related to muscle fatigue and ischemia. For flips and jumps, burst and cycle duration exhibited no regular pattern. The coefficient of variation in motor patterns was significantly greater for jumps and flips than for rhythmic swings. This supports the conclusion that the different tail behaviors do not stem from overlapping pattern generators, but that they rely upon independent neural circuits. The signal controlling jumps and flips may be modified by sensory information from the environment. Finally, we found that jumps and flips are initiated using relatively synchronous activity between the two sides of the tail. In contrast, alternating activation of the right and left sides of the tail result in rhythmic swings. The mechanism underlying this change in tail behavior is comparable to locomotor gait changes in vertebrates.

  9. Assessing Attachment in Psychotherapy

    DEFF Research Database (Denmark)

    Talia, Alessandro; Miller-Bottome, Madeleine; Daniel, Sarah I.F.

    2017-01-01

    The authors present and validate the Patient Attachment Coding System (PACS), a transcript-based instrument that assesses clients' in-session attachment based on any session of psychotherapy, in multiple treatment modalities. One-hundred and sixty clients in different types of psychotherapy...... (cognitive–behavioural, cognitive–behavioural-enhanced, psychodynamic, relational, supportive) and from three different countries were administered the Adult Attachment Interview (AAI) prior to treatment, and one session for each client was rated with the PACS by independent coders. Results indicate strong...... inter-rater reliability, and high convergent validity of the PACS scales and classifications with the AAI. These results present the PACS as a practical alternative to the AAI in psychotherapy research and suggest that clinicians using the PACS can assess clients' attachment status on an ongoing basis...

  10. Neural stem/progenitor cells are activated during tail regeneration in the leopard gecko (Eublepharis macularius).

    Science.gov (United States)

    Gilbert, E A B; Vickaryous, M K

    2018-02-01

    As for many lizards, the leopard gecko (Eublepharis macularius) can self-detach its tail to avoid predation and then regenerate a replacement. The replacement tail includes a regenerated spinal cord with a simple morphology: an ependymal layer surrounded by nerve tracts. We hypothesized that cells within the ependymal layer of the original spinal cord include populations of neural stem/progenitor cells (NSPCs) that contribute to the regenerated spinal cord. Prior to tail loss, we performed a bromodeoxyuridine pulse-chase experiment and found that a subset of ependymal layer cells (ELCs) were label-retaining after a 140-day chase period. Next, we conducted a detailed spatiotemporal characterization of these cells before, during, and after tail regeneration. Our findings show that SOX2, a hallmark protein of NSPCs, is constitutively expressed by virtually all ELCs before, during, and after regeneration. We also found that during regeneration, ELCs express an expanded panel of NSPC and lineage-restricted progenitor cell markers, including MSI-1, SOX9, and TUJ1. Using electron microscopy, we determined that multiciliated, uniciliated, and biciliated cells are present, although the latter was only observed in regenerated spinal cords. Our results demonstrate that cells within the ependymal layer of the original, regenerating and fully regenerate spinal cord represent a heterogeneous population. These include radial glia comparable to Type E and Type B cells, and a neuronal-like population of cerebrospinal fluid-contacting cells. We propose that spinal cord regeneration in geckos represents a truncation of the restorative trajectory observed in some urodeles and teleosts, resulting in the formation of a structurally distinct replacement. © 2017 Wiley Periodicals, Inc.

  11. The phylogenetic distribution, anatomy and histology of the post-cloacal bones and adnexa of geckos.

    Science.gov (United States)

    Russell, Anthony P; Vickaryous, Matthew K; Bauer, Aaron M

    2016-02-01

    Post-cloacal bones of gekkotans may be present as a single (medial) pair, two pairs (medial and lateral), or may be lacking. We, herein, demonstrate that the presence of a single medial pair is the ancestral condition for the Gekkota, that the lateral pair is of sporadic occurrence within and between families, except for the Eublepharidae where it is universal, and that absence is also of sporadic occurrence except for the Sphaerodactylidae where it is the ancestral condition. Adult male Tokay geckos (Gekko gecko) possess only the medial pair of bones, and these exhibit a regionally-specific expression of woven, fibrolamellar, and lamellar bone, and an enclosed medullary cavity. Females and small juvenile males lack bony elements but exhibit a conspicuous band of dense connective tissue located about the anterior and lateral margins of the cloacal sacs. As males grow and attain sexual maturity, the medial post-cloacal bones condense in this band of dense connective tissue, and are thus shown to be dermal ossifications, similar to osteoderms but with muscular associations (although this is also known for crocodylians). Based upon ontogenetic data we set forth a scenario to explain the loss of the medial post-cloacal bones in various lineages. Differential staining of the cloacal sacs failed to reveal any specialized glandular structures. Investigation of the post-cloacal spurs shows them to be associated with cellular connective tissue of a type similar to that found in the vicinity of the medial post-cloacal bones. This suggests that the lateral post-cloacal bones may also be dermal bones, but histological evidence is needed to corroborate this. © 2015 Wiley Periodicals, Inc.

  12. Interactions between hair cells shape spontaneous otoacoustic emissions in a model of the tokay gecko's cochlea.

    Directory of Open Access Journals (Sweden)

    Michael Gelfand

    2010-06-01

    Full Text Available The hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known to provide the energy for such emissions; it is unclear, though, how ensembles of such cells collude to power observable emissions.We have measured and modeled spontaneous otoacoustic emissions from the ear of the tokay gecko, a convenient experimental subject that produces robust emissions. Using a van der Pol formulation to represent each cluster of hair cells within a tonotopic array, we have examined the factors that influence the cooperative interaction between oscillators.A model that includes viscous interactions between adjacent hair cells fails to produce emissions similar to those observed experimentally. In contrast, elastic coupling yields realistic results, especially if the oscillators near the ends of the array are weakened so as to minimize boundary effects. Introducing stochastic irregularity in the strength of oscillators stabilizes peaks in the spectrum of modeled emissions, further increasing the similarity to the responses of actual ears. Finally, and again in agreement with experimental findings, the inclusion of a pure-tone external stimulus repels the spectral peaks of spontaneous emissions. Our results suggest that elastic coupling between oscillators of slightly differing strength explains several properties of the spontaneous otoacoustic emissions in the gecko.

  13. Interactions between hair cells shape spontaneous otoacoustic emissions in a model of the tokay gecko's cochlea.

    Science.gov (United States)

    Gelfand, Michael; Piro, Oreste; Magnasco, Marcelo O; Hudspeth, A J

    2010-06-15

    The hearing of tetrapods including humans is enhanced by an active process that amplifies the mechanical inputs associated with sound, sharpens frequency selectivity, and compresses the range of responsiveness. The most striking manifestation of the active process is spontaneous otoacoustic emission, the unprovoked emergence of sound from an ear. Hair cells, the sensory receptors of the inner ear, are known to provide the energy for such emissions; it is unclear, though, how ensembles of such cells collude to power observable emissions. We have measured and modeled spontaneous otoacoustic emissions from the ear of the tokay gecko, a convenient experimental subject that produces robust emissions. Using a van der Pol formulation to represent each cluster of hair cells within a tonotopic array, we have examined the factors that influence the cooperative interaction between oscillators. A model that includes viscous interactions between adjacent hair cells fails to produce emissions similar to those observed experimentally. In contrast, elastic coupling yields realistic results, especially if the oscillators near the ends of the array are weakened so as to minimize boundary effects. Introducing stochastic irregularity in the strength of oscillators stabilizes peaks in the spectrum of modeled emissions, further increasing the similarity to the responses of actual ears. Finally, and again in agreement with experimental findings, the inclusion of a pure-tone external stimulus repels the spectral peaks of spontaneous emissions. Our results suggest that elastic coupling between oscillators of slightly differing strength explains several properties of the spontaneous otoacoustic emissions in the gecko.

  14. Single-implant overdentures retained by the Novaloc attachment system: study protocol for a mixed-methods randomized cross-over trial.

    Science.gov (United States)

    de Souza, Raphael F; Bedos, Christophe; Esfandiari, Shahrokh; Makhoul, Nicholas M; Dagdeviren, Didem; Abi Nader, Samer; Jabbar, Areej A; Feine, Jocelyne S

    2018-04-23

    Overdentures retained by a single implant in the midline have arisen as a minimal implant treatment for edentulous mandibles. The success of this treatment depends on the performance of a single stud attachment that is susceptible to wear-related retention loss. Recently developed biomaterials used in attachments may result in better performance of the overdentures, offering minimal retention loss and greater patient satisfaction. These biomaterials include resistant polymeric matrixes and amorphous diamond-like carbon applied on metallic components. The objective of this explanatory mixed-methods study is to compare Novaloc, a novel attachment system with such characteristics, to a traditional alternative for single implants in the mandible of edentate elderly patients. We will carry out a randomized cross-over clinical trial comparing Novaloc attachments to Locators for single-implant mandibular overdentures in edentate elderly individuals. Participants will be followed for three months with each attachment type; patient-based, clinical, and economic outcomes will be gathered. A sample of 26 participants is estimated to be required to detect clinically relevant differences in terms of the primary outcome (patient ratings of general satisfaction). Participants will choose which attachment they wish to keep, then be interviewed about their experiences and preferences with a single implant prosthesis and with the two attachments. Data from the quantitative and qualitative assessments will be integrated through a mixed-methods explanatory strategy. A last quantitative assessment will take place after 12 months with the preferred attachment; this latter assessment will enable measurement of the attachments' long-term wear and maintenance requirements. Our results will lead to evidence-based recommendations regarding these systems, guiding providers and patients when making decisions on which attachment systems and implant numbers will be most appropriate for

  15. A unique method of retaining orbital prosthesis with attachment systems - a clinical report.

    Science.gov (United States)

    Guttal, Satyabodh S; Akash, N R; Prithviraj, D R; Lekha, K

    2014-06-01

    Diminution of the orbital contents post-surgical removal of a malignant tumor can have a severe psychological impact on the patient in terms of function and esthetics. Therefore, esthetic remedy should be planned subsequently, since tumor obliteration precedes cosmetic concern. A convenient option for successful rehabilitation in such patients is a simple, user-friendly, removable orbital prosthesis. Retention of the prosthesis is one of the key factors for the successful rehabilitation. Spectacle frame, conformers, adhesives, osseointegrated implants, magnets or buttons have been used to impart retention to the prosthesis. The use of semi precision attachments in maxillofacial prostheses is limited to the osseointegrated prostheses. This case report describes a conventional spectacle frame technique, to retain the silicone orbital prosthesis using two different types of stud attachments viz., dalla bona and O-ring attachment systems. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  16. Adhesion mechanism of a gecko-inspired oblique structure with an adhesive tip for asymmetric detachment

    International Nuclear Information System (INIS)

    Sekiguchi, Yu; Sato, Chiaki; Takahashi, Kunio

    2015-01-01

    An adhesion model of an oblique structure with an adhesive tip is proposed by considering a limiting stress for adhesion to describe the detachment mechanism of gecko foot hairs. When a force is applied to the root of the oblique structure, normal and shear stresses are generated at contact and the adhesive tip is detached from the surface when reaching the limiting stress. An adhesion criterion that considers both the normal and shear stresses is introduced, and the asymmetric detachment of the oblique structure is theoretically investigated. In addition, oblique beam array structures are manufactured, and an inclination effect of the structure on the asymmetric detachment is experimentally verified. (paper)

  17. Priming the Secure Attachment Schema Affects the Emotional Face Processing Bias in Attachment Anxiety: An fMRI Research

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2017-04-01

    Full Text Available Our study explored how priming with a secure base schema affects the processing of emotional facial stimuli in individuals with attachment anxiety. We enrolled 42 undergraduate students between 18 and 27 years of age, and divided them into two groups: attachment anxiety and attachment secure. All participants were primed under two conditions, the secure priming using references to the partner, and neutral priming using neutral references. We performed repeated attachment security priming combined with a dual-task paradigm and functional magnetic resonance imaging. Participants’ reaction times in terms of responding to the facial stimuli were also measured. Attachment security priming can facilitate an individual’s processing of positive emotional faces; for instance, the presentation of the partner’s name was associated with stronger activities in a wide range of brain regions and faster reaction times for positive facial expressions in the subjects. The current finding of higher activity in the left-hemisphere regions for secure priming rather than neutral priming is consistent with the prediction that attachment security priming triggers the spread of the activation of a positive emotional state. However, the difference in brain activity during processing of both, positive and negative emotional facial stimuli between the two priming conditions appeared in the attachment anxiety group alone. This study indicates that the effect of attachment secure priming on the processing of emotional facial stimuli could be mediated by chronic attachment anxiety. In addition, it highlights the association between higher-order processes of the attachment system (secure attachment schema priming and early-stage information processing system (attention, given the increased attention toward the effects of secure base schema on the processing of emotion- and attachment-related information among the insecure population. Thus, the following study has

  18. Attachment, caring and prosocial behavior

    NARCIS (Netherlands)

    Erez, Ayelet

    2007-01-01

    The thesis focuses on 5 studies examining the role of adult attachment in volunteering by defining volunteerism as a form of caregiving. By that we suggest an effect of one behavioral system, attachment, on another, caring or prosocial behaviors in individual or group settings. Studies 1 and 2

  19. Why social attachment and oxytocin protect against addiction and stress: Insights from the dynamics between ventral and dorsal corticostriatal systems.

    NARCIS (Netherlands)

    Tops, M.; Koole, S.L.; IJzerman, H.; Buisman-Pijlman, F.T.

    2014-01-01

    The present article advances a neurobiological model of the reciprocal associations between social attachment and drug abuse, and social attachment and chronic stress, as overlapping systems are involved in stress coping and social attachment. In terms of coping, responding to a novel stressor or

  20. Why social attachment and oxytocin protect against addiction and stress : Insights from the dynamics between ventral and dorsal corticostriatal systems

    NARCIS (Netherlands)

    Tops, M.; Koole, S.L.; Ijzerman, H.; Buisman-Pijlman, F.T.A.

    2014-01-01

    The present article advances a neurobiological model of the reciprocal associations between social attachment and drug abuse, and social attachment and chronic stress, as overlapping systems are involved in stress coping and social attachment. In terms of coping, responding to a novel stressor or

  1. A revised design approach of the attachment system for the ITER EU-HCPB-TBM based on a central cylindrical connection element

    International Nuclear Information System (INIS)

    Zeile, Christian; Neuberger, Heiko

    2012-01-01

    Highlights: ► Design of an attachment system based on a cylinder to connect TBM and shield. ► Attachment system has to cope with high EM loads and different thermal expansions. ► Stiff design and central position fulfill these requirements. ► Transient thermal-structural analyses confirm compliance of design with design codes. - Abstract: The EU-Helium Cooled Pebble Bed Test Blanket Module (HCPB-TBM), which is located inside an equatorial port plug, is attached to the shield by an attachment system. The design of the attachment system has to fulfill two conflicting requirements. On the one hand, it has to transfer the high electromagnetic forces acting on the TBM to the shield and on the other hand, it has to compensate the different thermal expansions between the shield and the back plate of the TBM. The recent design approach of the attachment system consists of a hollow cylinder located at the center of the back plate. This design combines two advantages: a simple geometry and correspondingly low fabrication effort and the central location where the differential strain between back plate and shield is minimal. Static and transient thermal-structural analyses of the most demanding load cases, a fast vertical displacement event type II and the operation state tritium outgassing, have been performed to evaluate the design and confirm the compliance with the relevant design codes. A welded connection of the attachment system to the TBM back plate and a bolted connection in combination with a splined shaft is proposed for the shield side because of the dissimilar materials.

  2. Finite element analysis to compare complete denture and implant-retained overdentures with different attachment systems.

    Science.gov (United States)

    Barão, Valentim Adelino Ricardo; Assunção, Wirley Gonçalves; Tabata, Lucas Fernando; Delben, Juliana Aparecida; Gomes, Erica Alves; de Sousa, Edson Antonio Capello; Rocha, Eduardo Passos

    2009-07-01

    This finite element analysis compared stress distribution on complete dentures and implant-retained overdentures with different attachment systems. Four models of edentulous mandible were constructed: group A (control), complete denture; group B, overdenture retained by 2 splinted implants with bar-clip system; group C, overdenture retained by 2 unsplinted implants with o'ring system; and group D, overdenture retained by 2 splinted implants with bar-clip and 2 distally placed o'ring system. Evaluation was performed on Ansys software, with 100-N vertical load applied on central incisive teeth. The lowest maximum general stress value (in megapascal) was observed in group A (64.305) followed by groups C (119.006), D (258.650), and B (349.873). The same trend occurred in supporting tissues with the highest stress value for cortical bone. Unsplinted implants associated with the o'ring attachment system showed the lowest maximum stress values among all overdenture groups. Furthermore, o'ring system also improved stress distribution when associated with bar-clip system.

  3. The regenerated tail of juvenile leopard geckos (Gekkota: Eublepharidae: Eublepharis macularius) preferentially stores more fat than the original.

    Science.gov (United States)

    Russell, Anthony P; Lynn, Sabrina E; Powell, G Lawrence; Cottle, Andrew

    2015-06-01

    The tail of many species of lizard is used as a site of fat storage, and caudal autotomy is a widespread phenomenon among lizards. This means that caudal fat stores are at risk of being lost if the tail is autotomized. For fat-tailed species, such as the leopard gecko, this may be particularly costly. Previous work has shown that tail regeneration in juveniles of this species is rapid and that it receives priority for energy allocation, even when dietary resources are markedly reduced. We found that the regenerated tails of juvenile leopard geckos are more massive than their original counterparts, regardless of dietary intake, and that they exhibit greater amounts of skeleton, inner fat, muscle and subcutaneous fat than original tails (as assessed through cross-sectional area measurements of positionally equivalent stations along the tail). Autotomy and regeneration result in changes in tail shape, mass and the pattern of tissue distribution within the tail. The regenerated tail exhibits enhanced fat storage capacity, even in the face of a diet that results in significant slowing of body growth. Body growth is thus sacrificed at the expense of rapid tail growth. Fat stores laid down rapidly in the regenerating tail may later be used to fuel body growth or reproductive investment. The regenerated tail thus seems to have adaptive roles of its own, and provides a potential vehicle for studying trade-offs that relate to life history strategy. Copyright © 2015 Elsevier GmbH. All rights reserved.

  4. Assessment of the Simulated Molecular Composition with the GECKO-A Modeling Tool Using Chamber Observations for α-Pinene.

    Science.gov (United States)

    Aumont, B.; Camredon, M.; Isaacman-VanWertz, G. A.; Karam, C.; Valorso, R.; Madronich, S.; Kroll, J. H.

    2016-12-01

    Gas phase oxidation of VOC is a gradual process leading to the formation of multifunctional organic compounds, i.e., typically species with higher oxidation state, high water solubility and low volatility. These species contribute to the formation of secondary organic aerosols (SOA) viamultiphase processes involving a myriad of organic species that evolve through thousands of reactions and gas/particle mass exchanges. Explicit chemical mechanisms reflect the understanding of these multigenerational oxidation steps. These mechanisms rely directly on elementary reactions to describe the chemical evolution and track the identity of organic carbon through various phases down to ultimate oxidation products. The development, assessment and improvement of such explicit schemes is a key issue, as major uncertainties remain on the chemical pathways involved during atmospheric oxidation of organic matter. An array of mass spectrometric techniques (CIMS, PTRMS, AMS) was recently used to track the composition of organic species during α-pinene oxidation in the MIT environmental chamber, providing an experimental database to evaluate and improve explicit mechanisms. In this study, the GECKO-A tool (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) is used to generate fully explicit oxidation schemes for α-pinene multiphase oxidation simulating the MIT experiment. The ability of the GECKO-A chemical scheme to explain the organic molecular composition in the gas and the condensed phases is explored. First results of this model/observation comparison at the molecular level will be presented.

  5. Blood vessel formation during tail regeneration in the leopard gecko (Eublepharis macularius): The blastema is not avascular.

    Science.gov (United States)

    Payne, Samantha L; Peacock, Hanna M; Vickaryous, Matthew K

    2017-03-01

    Unique among amniotes, many lizards are able to self-detach (autotomize) their tail and then regenerate a replacement. Tail regeneration involves the formation of a blastema, an accumulation of proliferating cells at the site of autotomy. Over time, cells of the blastema give rise to most of the tissues in the replacement tail. In non-amniotes capable of regenerating (such as urodeles and some teleost fish), the blastema is reported to be essentially avascular until tissue differentiation takes place. For tail regenerating lizards less is known. Here, we investigate neovascularization during tail regeneration in the leopard gecko (Eublepharis macularius). We demonstrate that the gecko tail blastema is not an avascular structure. Beginning with the onset of regenerative outgrowth, structurally mature (mural cell supported) blood vessels are found within the blastema. Although the pattern of blood vessel distribution in the regenerate tail differs from that of the original, a hierarchical network is established, with vessels of varying luminal diameters and wall thicknesses. Using immunostaining, we determine that blastema outgrowth and tissue differentiation is characterized by a dynamic interplay between the pro-angiogenic protein vascular endothelial growth factor (VEGF) and the anti-angiogenic protein thrombospondin-1 (TSP-1). VEGF-expression is initially widespread, but diminishes as tissues differentiate. In contrast, TSP-1 expression is initially restricted but becomes more abundant as VEGF-expression wanes. We predict that variation in the neovascular response observed between different regeneration-competent species likely relates to the volume of the blastema. J. Morphol. 278:380-389, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  6. DNA barcoding of Vietnamese bent-toed geckos (Squamata: Gekkonidae: Cyrtodactylus) and the description of a new species.

    Science.gov (United States)

    Nguyen, Sang Ngoc; Yang, Jun-Xiao; Le, Thanh-Ngan Thi; Nguyen, Luan Thanh; Orlov, Nikolai L; Hoang, Chung Van; Nguyen, Truong Quang; Jin, Jie-Qiong; Rao, Ding-Qi; Hoang, Thao Ngoc; Che, Jing; Murphy, Robert W; Zhang, Ya-Ping

    2014-03-26

    Species of bent-toed gecko (Cyrtodactylus) in Vietnam have been described at a rate of nearly four species per year since 2007 mostly based on morphological data. A tool that guides species delimitation will accelerate the rate of documentation, and at a time when the recognition of species greatly benefits conservation. We use DNA barcoding using COI (550 bp) to re-examine the levels of genetic divergence and taxonomic status of 21 described species of Vietnamese bent-toed geckos. Tree-based analyses resolve all sampled species and identify potential undescribed taxa. Kimura 2-parameter genetic distances between the described species average 21.0±4.2% and range from 4.3% to 28.7%. Further, our analyses discover two potentially new species from Vietnam, two from Laos and one from China. Herein we describe the new species Cyrtodactylus puhuensis sp. nov. from Vietnam on the basis of both genetics and morphology. Genetically, it differs from the remaining species by an average K2P distance of 24.0±1.8%. Morphologically, the new species is diagnosed by its medium-size (snout-vent length 79.24 mm and tail length 82.59 mm, for the single known individual), in having a series of moderately enlarged transverse subcaudals and a series of moderately enlarged femoral scales that extend from precloacal scales, in possessing femoral scales without pores, with males having five precloacal pores, and in exhibiting 8 supralabials, 10 infralabials, 23 narrow subdigital lamellae on its fourth toe, and 36 transverse ventrals.

  7. Paternal Attachment, Parenting Beliefs and Children's Attachment

    Science.gov (United States)

    Howard, Kimberly S.

    2010-01-01

    Relationships between fathers' romantic attachment style, parenting beliefs and father-child attachment security and dependence were examined in a diverse sample of 72 fathers of young children. Paternal romantic attachment style was coded based on fathers' endorsement of a particular style represented in the Hazan and Shaver Three-Category…

  8. UNSEDATED COMPUTED TOMOGRAPHY FOR DIAGNOSIS OF PELVIC CANAL OBSTRUCTION IN A LEOPARD GECKO (EUBLEPHARIS MACULARIUS).

    Science.gov (United States)

    DeCourcy, Kelly; Hostnik, Eric T; Lorbach, Josh; Knoblaugh, Sue

    2016-12-01

    An adult leopard gecko ( Eublepharis macularius ) presented for lethargy, hyporexia, weight loss, decreased passage of waste, and a palpable caudal coelomic mass. Computed tomography showed a heterogeneous hyperattenuating (∼143 Hounsfield units) structure within the right caudal coelom. The distal colon-coprodeum lumen or urinary bladder was hypothesized as the most likely location for the heterogeneous structure. Medical support consisted of warm water and lubricant enema, as well as a heated environment. Medical intervention aided the passage of a plug comprised centrally of cholesterol and urates with peripheral stratified layers of fibrin, macrophages, heterophils, and bacteria. Within 24 hr, a follow-up computed tomography scan showed resolution of the pelvic canal plug.

  9. Relative apportioning of resources to the body and regenerating tail in juvenile leopard geckos (Eublepharis macularius) maintained on different dietary rations.

    Science.gov (United States)

    Lynn, Sabrina E; Borkovic, Benjamin P; Russell, Anthony P

    2013-01-01

    Caudal autotomy is a widespread phenomenon among lizards, and similar processes occur in other groups of vertebrates and invertebrates. Many costs have been associated with autotomy, including the regeneration of lost biomass. For lizards, it is not known whether resources are preferentially directed toward caudal regeneration or whether regeneration occurs only when resources are abundant. Conflicting information is present in the literature, and an absence of controlled experiments prevents determination of what pattern of regeneration may occur under a given set of circumstances. We employed the leopard gecko, a fat-tailed species, to examine whether tail regeneration is a priority and, if so, whether it remains so when resources become limiting. We explored this through caudal autotomy and dietary manipulation under conditions that ensured that differences in diet were sufficient to permit differential growth. We examined juvenile leopard geckos because these animals are rapidly growing and allocation of energy is not compromised by reproductive investment. The effects of dietary resource availability and the demands of caudal regeneration were compared in intact and regenerating animals. Our evidence indicates that caudal regeneration is a priority, even when resources are limiting. We conclude that tail regrowth is a priority that is associated with long-term survival and possibly reproductive success.

  10. Impact of Maternal Attachment Style on Mother to Infant Attachment

    Directory of Open Access Journals (Sweden)

    Moghaddam Hoseini V

    2011-08-01

    Full Text Available Background and Objectives: Maternal attachment has the potential to affect both child development and parenting. As such, mother-infant attachment has been considered an important topic in recent years. The aim of this study was to determine the relationship between maternal adult attachment style, the maternal obstetric and demographic characteristics and mother-infant attachment.Methods: In this descriptive-correlational study, 102 women who had referred to health centers in Mashhad in 2008 and who had inclusion criteriawere selected using stratified cluster sampling. After interview about obstetric and demographic characteristics, they were asked to complete the "Revised Adult Attachment Scale" and "Mother to Infant Attachment Inventory" for assessment of maternal attachment style and mother-infant attachment 4-5 weeks after delivery. Data were analyzed by Pearson Correlation, Kruskal-wallis and Mann-whitney statistical tests.Results: In this study, themean of mother-infant attachment was found to be 97.486.12 and the mean of secure adult attachment was higher than that of other styles (16.893.97. Although, there were negative significant relationship between maternal avoidant style and mother-infant attachment (p=0.037,r=-0/20, there were no relationship between maternal age and education, parity, type of delivery and mother-infant attachment.Conclusion: The results of this research show that maternal attachment style is one of the factors of mother -infant attachment.

  11. Internal Representational Models of Attachment Relationships.

    Science.gov (United States)

    Crittenden, Patricia M.

    This paper outlines several properties of internal representational models (IRMs) and offers terminology that may help to differentiate the models. Properties of IRMs include focus, memory systems, content, cognitive function, "metastructure," quality of attachment, behavioral strategies, and attitude toward attachment. An IRM focuses on…

  12. Japanese children's family drawings and their link to attachment.

    Science.gov (United States)

    Behrens, Kazuko Y; Kaplan, Nancy

    2011-09-01

    This study explored the applicability of family drawings as a tool to estimate attachment security in a sample of Japanese six-year-olds (N = 47), applying Kaplan and Main's ( 1986 ) Family Drawing system. Maternal secure/insecure attachment status judged by the Adult Attachment Interview predicted family drawings' secure/insecure distinction produced by Japanese six-year-olds. However, insecure Japanese drawings took forms not seen in the original Berkeley drawings, such as a lineup of faces alone. Further examination of the Japanese children's drawings using global rating scales (Fury, Carlson, & Sroufe, 1997 ) yielded significant gender differences, rarely reported in the attachment literature, with girls scoring higher in scales that predict attachment security and boys scoring higher in scales that predict attachment insecurity. However, attachment security, as captured in the drawings, was not related to attachment security, observed behaviorally using Main and Cassidy's ( 1988 ) sixth-year reunion system. Implications of the findings are discussed in light of measurements, gender, and culture.

  13. Adult Attachment Style and Suicidality.

    Science.gov (United States)

    Miniati, Mario; Callari, Antonio; Pini, Stefano

    2017-09-01

    There is evidence in the literature that adverse early attachment experiences and subsequent attachment insecurities during adulthood would lead to pessimism, low self-esteem, hopelessness and, ultimately, to suicide risk. This paper aims to review finding on the link between attachment style and suicidality. We searched the literature using the database of the U.S. National Center for Biotechnology Information (NCBI)-MedLine/Pubmed system from January 1992 until December 2016. We started with 1992 because, as far as we know, there are no published studies exploring the relationship between suicide and insecure attachment before that year. We considered reports published on the relationship between attachment style and suicidality. We applied several combinations of the following search terms: attachment, adult attachment style and suicidality, suicide, suicidal ideation, suicidal behavior or suicidal thoughts, and suicide attempts. We selected only English language studies. Research suggests that insecure attachment style, mostly anxious, and unresolved traumas are associated with an increased suicide risk. Few studies prospectively examined clinical course, comorbid psychiatric disorders, familial suicidality or other psychosocial factors. Further research is needed to highlight the nature of the link between attachment and suicidality. The presence of suicidal ideation and attempts might be a consequence of an underlying interaction between the emergence of psychiatrics symptoms, and the long-lasting presence of inadequate patterns of attachment. Within this context, Separation Anxiety Disorder, categorized in the DSM-5 as a condition not confined to childhood but as an anxiety disorder that may occur through the entire lifespan, might be the a key for the comprehension of this link. From a neurobiological point of view, the role of oxytocin remains unclear.

  14. Bioinspired pressure actuated adhesive system

    NARCIS (Netherlands)

    Paretkar, D.R.; Kamperman, M.M.G.; Schneider, A.S.; Martina, D.; Creton, C.; Arzt, E.

    2011-01-01

    We developed a dry synthetic adhesive system inspired by gecko feet adhesion that can switch reversibly from adhesion to non-adhesion with applied pressure as external stimulus. Micropatterned polydimethylsiloxane (PDMS) surfaces with pillars of 30 µm length and 10 µm diameter were fabricated using

  15. Attachment theory: A review of research

    Directory of Open Access Journals (Sweden)

    Polovina Nada

    2005-01-01

    Full Text Available Research of attachment is numerous and versatile. They differ according to problems addressed, methodology applied (longitudinal studies, studies with horizontal designs, different instruments used, different methods of data analysis, and characteristics of samples involved (concerning age socio/economic status, family ecology. The research is commonly relied on the core assumptions of the theory itself, and the shared characteristic is orientation to explore complex phenomena of human experience and functioning. From the vast variety of research only those who most directly test the basic assumptions of the attachment theory are focused and addressed in the paper: representation of patterns of attachment in the childhood and adulthood, stability and change of attachment security from infancy to early adulthood, transgenerational transmission of attachment characteristics, the place and the role of attachment behavioral system in the personality development. The aim of the paper is to highlight the basic research and theory issues and directions, and illustrate them with concrete research date.

  16. Community dynamics of attached and free cells and the effects of attached cells on chalcopyrite bioleaching by Acidithiobacillus sp.

    Science.gov (United States)

    Yang, Hailin; Feng, Shoushuai; Xin, Yu; Wang, Wu

    2014-02-01

    The community dynamics of attached and free cells of Acidithiobacillus sp. were investigated and compared during chalcopyrite bioleaching process. In the mixed strains system, Acidithiobacillus ferrooxidans was the dominant species at the early stage while Acidithiobacillus thiooxidans owned competitive advantage from the middle stage to the end of bioprocess. Meanwhile, compared to A. ferrooxidans, more significant effects of attached cells on free biomass with A. thiooxidans were shown in either the pure or mixed strains systems. Moreover, the effects of attached cells on key chemical parameters were also studied in different adsorption-deficient systems. Consistently, the greatest reduction of key chemical ion was shown with A. thiooxidans and the loss of bioleaching efficiency was high to 50.5%. These results all demonstrated the bioleaching function of attached cells was more efficient than the free cells, especially with A. thiooxidans. These notable results would help us to further understand the chalcopyrite bioleaching. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Impact of Maternal Attachment Style on Mother to Infant Attachment

    Directory of Open Access Journals (Sweden)

    V Moghaddam Hoseini

    2012-05-01

    Full Text Available

    Background and Objectives: Maternal attachment has the potential to affect both child development and parenting. As such, mother-infant attachment has been considered an important topic in recent years. The aim of this study was to determine the relationship between maternal adult attachment style, the maternal obstetric and demographic characteristics and mother-infant attachment.

     

    Methods: In this descriptive-correlational study, 102 women who had referred to health centers in Mashhad in 2008 and who had inclusion criteriawere selected using stratified cluster sampling. After interview about obstetric and demographic characteristics, they were asked to complete the "Revised Adult Attachment Scale" and "Mother to Infant Attachment Inventory" for assessment of maternal attachment style and mother-infant attachment 4-5 weeks after delivery. Data were analyzed by Pearson Correlation, Kruskal-wallis and Mann-whitney statistical tests.

     

    Results: In this study, themean of mother-infant attachment was found to be 97.48±6.12 and the mean of secure adult attachment was higher than that of other styles (16.89±3.97. Although, there were negative significant relationship between maternal avoidant style and mother-infant attachment (p=0.037,r=-0/20, there were no relationship between maternal age and education, parity, type of delivery and mother-infant attachment.

     

    Conclusion: The results of this research show that maternal attachment style is one of the factors of mother -infant attachment.

  18. The Multimodal Assessment of Adult Attachment Security: Developing the Biometric Attachment Test.

    Science.gov (United States)

    Parra, Federico; Miljkovitch, Raphaële; Persiaux, Gwenaelle; Morales, Michelle; Scherer, Stefan

    2017-04-06

    Attachment theory has been proven essential for mental health, including psychopathology, development, and interpersonal relationships. Validated psychometric instruments to measure attachment abound but suffer from shortcomings common to traditional psychometrics. Recent developments in multimodal fusion and machine learning pave the way for new automated and objective psychometric instruments for adult attachment that combine psychophysiological, linguistic, and behavioral analyses in the assessment of the construct. The aim of this study was to present a new exposure-based, automatic, and objective adult-attachment assessment, the Biometric Attachment Test (BAT), which exposes participants to a short standardized set of visual and music stimuli, whereas their immediate reactions and verbal responses, captured by several computer sense modalities, are automatically analyzed for scoring and classification. We also aimed to empirically validate two of its assumptions: its capacity to measure attachment security and the viability of using themes as placeholders for rotating stimuli. A total of 59 French participants from the general population were assessed using the Adult Attachment Questionnaire (AAQ), the Adult Attachment Projective Picture System (AAP), and the Attachment Multiple Model Interview (AMMI) as ground truth for attachment security. They were then exposed to three different BAT stimuli sets, whereas their faces, voices, heart rate (HR), and electrodermal activity (EDA) were recorded. Psychophysiological features, such as skin-conductance response (SCR) and Bayevsky stress index; behavioral features, such as gaze and facial expressions; as well as linguistic and paralinguistic features, were automatically extracted. An exploratory analysis was conducted using correlation matrices to uncover the features that are most associated with attachment security. A confirmatory analysis was conducted by creating a single composite effects index and by testing it

  19. Cyrtodactylus tahuna sp. nov., a new bent-toed gecko (Reptilia: Squamata: Gekkonidae) from Sangihe Island, North Sulawesi, Indonesia.

    Science.gov (United States)

    Riyanto, Awal; Arida, Evy; Koch, AndrÉ

    2018-03-21

    Cyrtodactylus tahuna sp. nov. is a new bent-toed gecko we describe herein based on three specimens from Sangihe, North Sulawesi, Indonesia, an island situated in the northern corner of the Wallacea biodiversity hotspot. The new species is a medium sized Cyrtodactylus with a SVL of up to 78.5 mm in adult males and 79.2 mm in females. It is easily distinguished from all but four species (Cyrtodactylus fumosus, C. halmahericus, C. papuensis, and C. tambora) occurring on Sulawesi as well as in the Moluccas and the Lesser Sunda Islands, by possessing precloacal and femoral pores, enlarged precloacal and femoral scales, and lacking transversely enlarged median subcaudal scales. It differs from C. fumosus by the presence of tubercles on the ventrolateral fold, more unkeeled dorsal tubercles (19 versus 4-7) and a pit-like precloacal depression in males (versus groove in males); from C. halmahericus by presence of smaller scales between the enlarged precloacal and femoral scales (versus a continuous series of enlarged precloacofemoral scales) and a continuous series of precloacofemoral pores, as well as the presence of a pit-like precloacal depression in male (versus groove in males), from C. papuensis by possessing a pit-like precloacal depression in males (versus a groove ); and from C. tambora by the presence of tubercles on the dorsal surface of the brachium and the possession of femoral pores. Our contribution, along with several other recent descriptions of bent-toad geckos from Southeast Asia, clearly indicating that the diversity of the genus Cyrtodactylus in Indonesia is still underestimated.

  20. Rapid forest clearing in a Myanmar proposed national park threatens two newly discovered species of geckos (Gekkonidae: Cyrtodactylus.

    Directory of Open Access Journals (Sweden)

    Grant M Connette

    Full Text Available Myanmar's recent transition from military rule towards a more democratic government has largely ended decades of political and economic isolation. Although Myanmar remains heavily forested, increased development in recent years has been accompanied by exceptionally high rates of forest loss. In this study, we document the rapid progression of deforestation in and around the proposed Lenya National Park, which includes some of the largest remaining areas of lowland evergreen rainforest in mainland Southeast Asia. The globally unique forests in this area are rich in biodiversity and remain a critical stronghold for many threatened and endangered species, including large charismatic fauna such as tiger and Asian elephant. We also conducted a rapid assessment survey of the herpetofauna of the proposed national park, which resulted in the discovery of two new species of bent-toed geckos, genus Cyrtodactylus. We describe these new species, C. lenya sp. nov. and C. payarhtanensis sp. nov., which were found in association with karst (i.e., limestone rock formations within mature lowland wet evergreen forest. The two species were discovered less than 35 km apart and are each known from only a single locality. Because of the isolated nature of the karst formations in the proposed Lenya National Park, these geckos likely have geographical ranges restricted to the proposed protected area and are threatened by approaching deforestation. Although lowland evergreen rainforest has vanished from most of continental Southeast Asia, Myanmar can still take decisive action to preserve one of the most biodiverse places on Earth.

  1. Rapid forest clearing in a Myanmar proposed national park threatens two newly discovered species of geckos (Gekkonidae: Cyrtodactylus).

    Science.gov (United States)

    Connette, Grant M; Oswald, Patrick; Thura, Myint Kyaw; LaJeunesse Connette, Katherine J; Grindley, Mark E; Songer, Melissa; Zug, George R; Mulcahy, Daniel G

    2017-01-01

    Myanmar's recent transition from military rule towards a more democratic government has largely ended decades of political and economic isolation. Although Myanmar remains heavily forested, increased development in recent years has been accompanied by exceptionally high rates of forest loss. In this study, we document the rapid progression of deforestation in and around the proposed Lenya National Park, which includes some of the largest remaining areas of lowland evergreen rainforest in mainland Southeast Asia. The globally unique forests in this area are rich in biodiversity and remain a critical stronghold for many threatened and endangered species, including large charismatic fauna such as tiger and Asian elephant. We also conducted a rapid assessment survey of the herpetofauna of the proposed national park, which resulted in the discovery of two new species of bent-toed geckos, genus Cyrtodactylus. We describe these new species, C. lenya sp. nov. and C. payarhtanensis sp. nov., which were found in association with karst (i.e., limestone) rock formations within mature lowland wet evergreen forest. The two species were discovered less than 35 km apart and are each known from only a single locality. Because of the isolated nature of the karst formations in the proposed Lenya National Park, these geckos likely have geographical ranges restricted to the proposed protected area and are threatened by approaching deforestation. Although lowland evergreen rainforest has vanished from most of continental Southeast Asia, Myanmar can still take decisive action to preserve one of the most biodiverse places on Earth.

  2. Evaluation of the attractive force of different types of new-generation magnetic attachment systems.

    Science.gov (United States)

    Akin, Hakan; Coskun, M Emre; Akin, E Gulsah; Ozdemir, A Kemal

    2011-03-01

    Rare earth magnets have been used in prosthodontics, but their tendency for corrosion in the oral cavity and insufficient attractive forces limit long-term clinical application. The purpose of this study was to evaluate the attractive force of different types of new-generation magnetic attachment systems. The attractive force of the neodymium-iron-boron (Nd-Fe-B) and samarium-cobalt (Sm-Co) magnetic attachment systems, including closed-field (Hilop and Hicorex) and open-field (Dyna and Steco) systems, was measured in a universal testing machine (n=5). The data were statistically evaluated with 1-way ANOVA and post hoc Tukey-Kramer multiple comparison test (α=.05). The closed-field systems exhibited greater (Pattractive force than the open-field systems. Moreover, there was a statistically significant difference in attractive force between Nd-Fe-B and Sm-Co magnets (Pattractive force was found with the Hilop system (9.2 N), and the lowest force was found with the Steco system (2.3 N). The new generation of Nd-Fe-B closed-field magnets, along with improved technology, provides sufficient denture retention for clinical application. Copyright © 2011 The Editorial Council of the Journal of Prosthetic Dentistry. Published by Mosby, Inc. All rights reserved.

  3. Incubation temperature affects the behavior of adult leopard geckos (Eublepharis macularius).

    Science.gov (United States)

    Flores, D; Tousignant, A; Crews, D

    1994-06-01

    The leopard gecko has temperature-dependent sex determination (TSD); females are predominantly produced when incubated at 26 degrees C (100%), 30 degrees C (70%), and 34 degrees C (95%), whereas males are predominantly produced at 32.5 degrees C (75%). Exogenous estradiol can override the effect of temperature on sex determination. To compare temperature-determined females with hormone-determined females, eggs from the male-biased temperature were treated with estradiol benzoate during incubation. As adults, animals from a male-biased incubation temperature were more likely to exhibit aggression than animals from female-biased incubation temperatures. Furthermore, females from a male-biased incubation temperature tended to be less attractive than females from female-biased temperatures. Hormone-determined females were both attractive and aggressive. This suggests that incubation temperature is an important development determinant of adult aggressiveness and attractiveness. The 26 degrees C animals ovariectomized on the day of hatch exhibited more frequent aggression and were unreceptive to males, indicating that postnatal ovarian hormones also play a role in adult sociosexual behaviors. The parallel between incubation temperature and intrauterine position in laboratory mammals is discussed.

  4. Examining antecedents of infant attachment security with mothers and fathers: An ecological systems perspective☆

    OpenAIRE

    Lickenbrock, Diane M.; Braungart-Rieker, Julia M.

    2015-01-01

    Taking an ecological systems perspective, early parent–child relationships can be affected by interactions between systems where some are more proximally linked to the child than others. Socioeconomic status, a distal factor, is associated with social functioning during childhood, but research on its association with functioning during infancy, particularly attachment, is scant and inconsistent. Moreover, it is not clear how distal factors affect infant functioning. Other systems such as mari...

  5. Attachment style and interpersonal trauma in refugees.

    Science.gov (United States)

    Morina, Naser; Schnyder, Ulrich; Schick, Matthis; Nickerson, Angela; Bryant, Richard A

    2016-12-01

    Refugees can suffer many experiences that threaten their trust in others. Although models of refugee mental health have postulated that attachment securities may be damaged by refugee experiences, this has yet to be empirically tested. This study aimed to understand the relationship between the nature of traumatic experiences sustained by refugees and attachment styles. In a cross-sectional study, treatment-seeking refugees (N = 134) were assessed for traumatic exposure using the Harvard Trauma Questionnaire and Posttraumatic Diagnostic Scale. Attachment style was assessed using the Experiences in Close Relationship Scale. Whereas gender and severity of interpersonal traumatic events predicted avoidant attachment style (accounting for 11% of the variance), neither these factors nor non-interpersonal trauma predicted anxious attachment. Exposure to interpersonal traumatic events, including torture, is associated with enduring avoidant attachment tendencies in refugees. This finding accords with attachment theories that prior adverse interpersonal experiences can undermine secure attachment systems, and may promote avoidance of attachment seeking. This finding may point to an important process maintaining poor psychological health in refugees affected by interpersonal trauma. © The Royal Australian and New Zealand College of Psychiatrists 2016.

  6. Attachment Theory in Supervision: A Critical Incident Experience

    Science.gov (United States)

    Pistole, M. Carole; Fitch, Jenelle C.

    2008-01-01

    Critical incident experiences are a powerful source of counselor development (T. M. Skovholt & P. R. McCarthy, 1988a, 1988b) and are relevant to attachment issues. An attachment theory perspective of supervision is presented and applied to a critical incident case scenario. By focusing on the behavioral systems (i.e., attachment, caregiving, and…

  7. Attachment and Psychopathology

    Directory of Open Access Journals (Sweden)

    Mehmet Fatih Ustundag

    2011-06-01

    Full Text Available The type of attachment defined in the early stages of life and thought to be continuous, is a phenomenon that shapes the pattern of how a person makes contact with others. The clinical appearance of every type of attachment is different and each one has prospective and retrospective phenomenological reflections. In all stages of life and in close relationships, it can be observed if a person gets in close contact with someone else and if this relation bears supportive and protective qualities. According to attachment theorists, once it is defined as safe or unsafe during nursing period, it shows little change. Starting from Bowlby’s work, unsafe attachment type is considered as the determining factor of psychopathology in the later periods of life, while safe attachment is considered as in relation with healthy processes. The nature’s original model is safe attachment. Anxious/indecisive attachment, an unsafe attachment type, is associated with anxiety disorders and depressive disorder, while avoidant attachment is associated with behavior disorder and other extroverted pathologies. Disorganized/disoriented attachment is considered to be together with dissociative disorder. The aim of this paper is to review attachment theory and the relation between attachment and psychopathology.

  8. Conserved and divergent expression patterns of markers of axial development in reptilian embryos: Chinese soft-shell turtle and Madagascar ground gecko.

    Science.gov (United States)

    Yoshida, Michio; Kajikawa, Eriko; Kurokawa, Daisuke; Noro, Miyuki; Iwai, Tatsuhiro; Yonemura, Shigenobu; Kobayashi, Kensaku; Kiyonari, Hiroshi; Aizawa, Shinichi

    2016-07-01

    The processes of development leading up to gastrulation have been markedly altered during the evolution of amniotes, and it is uncertain how the mechanisms of axis formation are conserved and diverged between mouse and chick embryos. To assess the conservation and divergence of these mechanisms, this study examined gene expression patterns during the axis formation process in Chinese soft-shell turtle and Madagascar ground gecko preovipositional embryos. The data suggest that NODAL signaling, similarly to avian embryos but in contrast to eutherian embryos, does not have a role in epiblast and hypoblast development in reptilian embryos. The posterior marginal epiblast (PME) is the initial molecular landmark of axis formation in reptilian embryos prior to primitive plate development. Ontogenetically, PME may be the precursor of the primitive plate, and phylogenetically, Koller's sickle and posterior marginal zone in avian development may have been derived from the PME. Most of the genes expressed in the mouse anterior visceral endoderm (AVE genes), especially signaling antagonist genes, are not expressed in the hypoblast of turtle and gecko embryos, though they are expressed in the avian hypoblast. This study proposes that AVE gene expression in the hypoblast and the visceral endoderm could have been independently established in avian and eutherian lineages, similar to the primitive streak that has been independently acquired in these lineages. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Perceived hunger mediates the relationship between attachment anxiety and emotional eating.

    Science.gov (United States)

    Alexander, Katherine E; Siegel, Harold I

    2013-08-01

    Eating is an inherently emotional activity and the attachment system is an emotion regulation system. Individuals with attachment insecurity have less interoceptive awareness and difficulty regulating emotion. Insecurely attached individuals may eat emotionally because they misinterpret internal hunger cues, (i.e. think they are hungry when they are experiencing some other internal, attachment-related state). The current study found a positive association between attachment anxiety and emotional eating. This relationship was mediated by perceived hunger. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Attachment patterns and Reflective Functioning in Traumatized Refugees

    DEFF Research Database (Denmark)

    Riber, Karin

    , attachment systems, emotion-regulation, and personality. Attachment research on the consequences of organized violence and forced migration is sparse and research in PTSD-treatment for refugees is lacking behind. Cumulative pre-migration traumatic experiences and ongoing post-migration stressors might lead...... Psychiatry, Denmark. June 2011-March 2012 patients fulfilling inclusion criteria entered the trial. The present sample consisted of those of the 135 patients who were Arabic-speaking (N=67). Measures involved the Adult Attachment Interview, The Reflective Functioning Scale, Revised Adult Attachment Scale...... and reflective functioning will be described and implications for psychotherapy discussed. Keywords: Adult attachment, reflective functioning, refugee traumatisation....

  11. Sexual dimorphism in the attachment ability of the ladybird beetle Coccinella septempunctata on soft substrates

    DEFF Research Database (Denmark)

    Heepe, Lars; Petersen, Dennis S.; Tölle, Lisa

    2017-01-01

    of insects and also that of spiders and geckos has been tested on rigid substrates only. However, the natural habitats of climbing animals may provide a variety of substrate stiffness ranging from rigid rock surfaces to soft, biofilm covered substrates. In order to test the effect of different substrate...

  12. Chewing efficiency and maximum bite force with different attachment systems of implant overdentures: a crossover study.

    Science.gov (United States)

    Elsyad, Moustafa Abdou; Khairallah, Ahmed Samir

    2017-06-01

    This crossover study aimed to evaluate and compare chewing efficiency and maximum bite force (MBF) with resilient telescopic and bar attachment systems of implant overdentures in patients with atrophied mandibles. Ten participants with severely resorbed mandibles and persistent denture problems received new maxillary and mandibular conventional dentures (control, CD). After 3 months of adaptation, two implants were inserted in canine region of the mandible. In a quasi-random method, overdentures were connected to the implants with either bar overdentures (BOD) or resilient telescopic overdentures (TOD) attachment systems. Chewing efficiency in terms of unmixed fraction (UF) was measured using chewing gum (after 5, 10, 20, 30 and 50 strokes), and MBF was measured using a bite force transducer. Measurements were performed 3 months after using each of the following prostheses: CD, BOD and TOD. Chewing efficiency and MBF increased significantly with BOD and TOD compared to CD. As the number of chewing cycles increased, the UF decreased. TOD recorded significant higher chewing efficiency and MBF than BOD. Resilient telescopic attachments are associated with increased chewing efficiency and MBF compared bar attachments when used to retain overdentures to the implants in patients with atrophied mandibles. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  13. Attachment and Temperament Revisited: Infant Distress, Attachment Disorganization, and the Serotonin Transporter Polymorphism.

    Science.gov (United States)

    Brumariu, Laura E; Bureau, Jean-François; Nemoda, Zsofia; Sasvari-Szekely, Maria; Lyons-Ruth, Karlen

    This study's aim was to evaluate whether infant disorganized attachment and infant proneness to distress exhibited differential relations to infant genetic factors as indexed by the serotonin transporter polymorphism. The role of the short allele of the serotonin transporter polymorphism (5-HTTLPR) in enhancing sensitivity to fearful and negative affect has been well-established (Canli & Lesch, 2007). In the current study, we used this known property of the short allele to provide a test of an important postulate of attachment theory, namely that infant attachment security or disorganization is not a function of the infant's proneness to distress. Participants were 39 parents and infants assessed between 12 and 18 months in the Strange Situation procedure. Genotype categories for the 5-HTTLPR (and rs25531) were created by both the original and the reclassified grouping system; infant proneness to distress was assessed directly in the Strange Situation Procedure. We also assessed maternal behavior at 18 months to evaluate whether any observed genetic effect indicated a passive effect through the mother. Consistent with previous findings, the 5-HTTLPR short allele was significantly related to the infant's wariness and distress, but was not related to attachment security or attachment disorganization. In addition, maternal disrupted interaction with the infant was not related to infant genotype or infant distress. Results support the concept that infant proneness to distress is associated with serotonergic factors while infant attachment security or disorganization is not a function of either 5-HTTLPR or behaviorally rated proneness to distress.

  14. The fourth Bent-toed Gecko of the genus Cyrtodactylus (Squamata: Gekkonidae) from Java, Indonesia.

    Science.gov (United States)

    Riyanto, Awal; Grismer, L Lee; Wood, Perry L

    2015-12-22

    Cyrtodactylus petani sp. nov. is a new species of Bent-toed Gecko from Java, Indonesia that had been masquerading under the name C. fumosus (Müller, 1895). The new species is differentiated from C. fumosus and all its Sundaland congeners by having the following combination of morphological characters: a maximum SVL of 57.2 mm; nine or ten supralabials; seven or eight infralabials; strongly tuberculate body and limbs; 20-25 paravertebral tubercles; 30-35 ventral scales; enlarged precloacal scales; enlarged femoral scales; 17-18 subdigital lamellae on the fourth toe; 31-35 continuous precloacal and femoral pores in males, pores absent in females; no precloacal groove; no enlarged median subcaudals; tubercles on anterior portion of tail; no reticulated pattern on top of head; a blotched dorsal pattern; and no paired, dark, semi-lunar shaped blotches on the nape.

  15. A new species of Rock Gecko genus Cnemaspis (Squamata: Gekkonidae) from Western Sarawak, Malaysia.

    Science.gov (United States)

    Kurita, Takaki; Nishikawa, Kanto; Matsui, Masafumi; Hikida, Tsutomu

    2017-05-03

    A new species of Asian rock gecko, genus Cnemaspis, is described from Padawan, western Sarawak, Malaysian Borneo. The new species forms a clade with C. paripari and C. nigridia of the C. nigridia group in a mitochondrial DNA phylogeny and is similar to them morphologically in some characters such as caudal scalation. It differs from the other Asian Cnemaspis species in its unique combination of snout-vent length (up to 62.7 mm), 4-9 precloacal pores in males, keeled subcaudals with an enlarged, smooth, median row, presence of ventrolateral caudal tubercles, and coloration (head and upper flanks dark-yellow; anterior portion of tail black; posterior portion of tail white with black, paravertebral blob). Phylogenetic relationships within the C. nigridia group and the distributional ranges of species within the group suggest allopatric speciation by geographic isolation.

  16. Effect of incubation temperature and androgens on dopaminergic activity in the leopard gecko, Eublepharis macularius.

    Science.gov (United States)

    Dias, Brian George; Ataya, Ramona Sousan; Rushworth, David; Zhao, Jun; Crews, David

    2007-04-01

    Male leopard geckos that hatch from eggs incubated at a female-biased temperature (Tf) behave differently when compared with males hatching at a temperature which produces a male-biased sex ratio (Tm). We investigated the effect of incubation temperature and androgen implantation on aspects of the dopaminergic system of Tf and Tm males. Our data suggest that more dopamine (DA) is stored in the nucleus accumbens of naive Tf males compared with naïve Tm males when they encounter a receptive female conspecific across a barrier. No difference was measured in the preoptic area and the ventral tegmental area (VTA). This difference in intracellular DA levels in a motivation-related brain nucleus might be correlated with differences in sociosexual behavior observed between the two morphs. There were no differences in tyrosine hydroxylase (TH) expressing cell numbers in the VTA of cholesterol (CH)-implanted naive castrated Tf and Tm males. Only Tf males implanted with testosterone had significantly higher TH immunopositive cell numbers in the VTA compared with CH- and dihydrotestosterone-implanted Tf males. These data indicate that both the embryonic environment as well as the circulating hormonal milieu can modulate neurochemistry, which might in turn be a basis for individual variation in behavior. Copyright (c) 2007 Wiley Periodicals, Inc.

  17. A Cognitive Attachment Model of prolonged grief: integrating attachments, memory, and identity.

    Science.gov (United States)

    Maccallum, Fiona; Bryant, Richard A

    2013-08-01

    Prolonged grief (PG), otherwise known as complicated grief, has attracted much attention in recent years as a potentially debilitating condition that affects approximately 10% of bereaved people. We propose a model of PG that integrates processes of attachment, self-identity, and autobiographical memory. The paper commences with a discussion of the PG construct and reviews current evidence regarding the distinctiveness of PG from other bereavement related-outcomes. We then review the evidence regarding the dysfunctional attachments, appraisals, and coping styles that people with PG display. Recent evidence pertaining to the patterns of autobiographical memory in PG is described in the context of the self-memory system. This system provides a unifying framework to understand the roles of personal memories, identity, attachments, and coping responses in PG. The proposed model places emphasis on how one's sense of identity influences yearning, memories of the deceased, appraisals, and coping strategies, to maintain a focus on the loss. The model is discussed in relation to existing models of PG. The potential for shaping treatment strategies to shift perceptions of the self is then outlined. Finally, we outline future directions to test propositions stemming from the model and enhance our understanding of the mechanisms underlying PG. Copyright © 2013 Elsevier Ltd. All rights reserved.

  18. Impact of Child Maltreatment on Attachment and Social Rank Systems: Introducing an Integrated Theory.

    Science.gov (United States)

    Sloman, Leon; Taylor, Peter

    2016-04-01

    Child maltreatment is a prevalent societal problem that has been linked to a wide range of social, psychological, and emotional difficulties. Maltreatment impacts on two putative evolved psychobiological systems in particular, the attachment system and the social rank system. The maltreatment may disrupt the child's ability to form trusting and reassuring relationships and also creates a power imbalance where the child may feel powerless and ashamed. The aim of the current article is to outline an evolutionary theory for understanding the impact of child maltreatment, focusing on the interaction between the attachment and the social rank system. We provide a narrative review of the relevant literature relating to child maltreatment and these two theories. This research highlights how, in instances of maltreatment, these ordinarily adaptive systems may become maladaptive and contribute to psychopathology. We identify a number of novel hypotheses that can be drawn from this theory, providing a guide for future research. We finally explore how this theory provides a guide for the treatment of victims of child maltreatment. In conclusion, the integrated theory provides a framework for understanding and predicting the consequences of maltreatment, but further research is required to test several hypotheses made by this theory. © The Author(s) 2015.

  19. Attachment representation in institutionalized children: a preliminary study using the child attachment interview.

    Science.gov (United States)

    Zaccagnino, Maria; Cussino, Martina; Preziosa, Alessandra; Veglia, Fabio; Carassa, Antonella

    2015-01-01

    The experience of being removed from one's home and the transition to a residential care system pose enormous challenges for a child. Substantial evidence has been found regarding severe developmental effects due to early exposition to extreme psychosocial and affective deprivation. The research on Bowlby's theoretical proposals has highlighted the link between insecure, disorganized and atypical attachment patterns and children both living in foster care facilities and adopted out of those institutions. The goal of this pilot study is to investigate the attachment representation in an Italian sample of children in middle childhood (9-13 years old) who have been removed from their homes. Two compared groups of children participated in this study. The first group was composed of 24 Italian children who had been removed from their homes. The second group, considered as the control group, was composed of 35 Italian children who had never been in foster care placement. The quality of children's attachment to their primary caregivers was assessed by the Child Attachment Interview, an innovative semi-structured interview that seeks to bridge the measurement gap identified in middle childhood The children in foster care placement show a higher percentage of insecure and disorganized attachment representations and lower scores on the Child Reflective Functioning Scale. The clinical implications and enhancements to effective intervention for foster children's caretaking are discussed. Copyright © 2014 John Wiley & Sons, Ltd.

  20. Diversity of functional microornamentation in slithering geckos Lialis (Pygopodidae).

    Science.gov (United States)

    Spinner, M; Gorb, S N; Westhoff, G

    2013-12-07

    The skin of geckos is covered with countless microscopic protuberances (spines). This surface structure causes low wettability to water. During evolution, representatives of the recent gekkotan clade Pygopodidae started slithering on the ground. This manner of locomotion affected limb reduction resulting in a snake-like body. Regarding abrasion and frictional properties, a surface covered with gekkotan spines is a topography that hampers the snake-like locomotion mode. Using scanning electron microscopy, we investigated the shed skins of two pygopodid lizards, Lialis jicari (Papua snake lizard) and Lialis burtonis (Burton's legless lizard), in order to show epidermal adaptations to limbless locomotion. Our data showed that Pygopodidae differ from their relatives not only anatomically, but also in their epidermal microstructure. Scales of L. jicari have five different structural patterns on various body regions. Ventral scales have nanoridges, similar to those found on the ventralia of snakes. Surfaces of scales covering the jaw bones, have flattened spine-like microstructures that might be an adaptation to reduce abrasion. Dorsal scales have oblong microscopic bulges covered with nanoridges. Spines cover the undersides and the interstices of scales over the entire body of both species and in L. jicari also the top of dorsal head scales. Our measurements of surface wettability (surface free energy) show superhydrophobic properties of the spiny surfaces in comparison with the other microstructural patterns of other body parts.

  1. Preferential attachment in evolutionary earthquake networks

    Science.gov (United States)

    Rezaei, Soghra; Moghaddasi, Hanieh; Darooneh, Amir Hossein

    2018-04-01

    Earthquakes as spatio-temporal complex systems have been recently studied using complex network theory. Seismic networks are dynamical networks due to addition of new seismic events over time leading to establishing new nodes and links to the network. Here we have constructed Iran and Italy seismic networks based on Hybrid Model and testified the preferential attachment hypothesis for the connection of new nodes which states that it is more probable for newly added nodes to join the highly connected nodes comparing to the less connected ones. We showed that the preferential attachment is present in the case of earthquakes network and the attachment rate has a linear relationship with node degree. We have also found the seismic passive points, the most probable points to be influenced by other seismic places, using their preferential attachment values.

  2. Why social attachment and oxytocin protect against addiction and stress: Insights from the dynamics between ventral and dorsal corticostriatal systems.

    Science.gov (United States)

    Tops, Mattie; Koole, Sander L; IJzerman, Hans; Buisman-Pijlman, Femke T A

    2014-04-01

    The present article advances a neurobiological model of the reciprocal associations between social attachment and drug abuse, and social attachment and chronic stress, as overlapping systems are involved in stress coping and social attachment. In terms of coping, responding to a novel stressor or challenge involves initial novelty processing and activation of learning mechanisms that allow habituation to the stressor through familiarization. Similarly, social attachments are initially formed by being attracted by rewarding properties of an as-yet novel individual, and subsequently developing feelings of attachment towards the familiarized individual. Attachment and familiarization increase the availability of "internal working models" for the control of behavior and emotion, which may explain why secure attachments are associated with increased resilience in the face of stress, accompanied by less reactive reward responding (i.e., increased resilience against drug addiction). The present article seeks to illuminate the role of the neuropeptide oxytocin, which may be involved in the overlapping mechanisms of stable attachment formation and stress coping by shifting processing from novelty and reward seeking to appreciation of familiarity. Oxytocin may accomplish this by facilitating a ventral-to-dorsal shift in activation in corticostriatal loops, which produces a shift from a reactive reward drive (wanting) to stable appreciation of familiar social aspects ("liking" or "loving"). The authors suggest that through dopaminergic, serotonergic and endogenous opioid mechanisms, oxytocin is involved in shifting the balance between wanting and liking in corticostriatal loops by facilitating consolidation of social information from ventral reactive reward systems to dorsal internal working models that aid in prospectively selecting optimal actions in the future, increasing resilience in the face of stress and addiction. © 2013.

  3. Ecomorphology of parasite attachment: experiments with feather lice.

    Science.gov (United States)

    Bush, Sarah E; Sohn, Edward; Clayton, Dale H

    2006-02-01

    The host specificity of some parasites can be reinforced by morphological specialization for attachment to mobile hosts. For example, ectoparasites with adaptations for attaching to hosts of a particular size might not be able to remain attached to larger or smaller hosts. This hypothesis is suggested by the positive correlation documented between the body sizes of many parasites and their hosts. We adopted an ecomorphological approach to test the attachment hypothesis. We tested the ability of host-specific feather lice (Phthiraptera: Ischnocera) to attach to 6 novel species of pigeons and doves that vary in size by nearly 2 orders of magnitude. Surprisingly, Rock Pigeon lice (Columbicola columbae) remained attached equally well to all 6 novel host species. We tested the relative importance of 3 factors that could facilitate louse attachment: whole-body insertion, tarsal claw use, and mandible use. Insertion, per se, was not necessary for attachment. However, insertion on coarse feathers of large hosts allowed lice to access feather barbules with their mandibles. Mandible use was a key component of attachment regardless of feather size. Attachment constraints do not appear to reinforce host specificity in this system.

  4. Tests of the Attachment and Developmental Dynamic Systems Theory of Crime (ADDSTOC): Toward a Differential RDoC Diagnostic and Treatment Approach.

    Science.gov (United States)

    Lindberg, Marc A; Zeid, Dana

    2018-01-01

    The Attachment and Developmental Dynamic Systems Theory of Crime was tested on 206 male inmates. They completed measures tapping attachments, clinical issues, adverse childhood events, peer crime, and crime addictions. A significant path model was found, going from insecure parental attachments to adverse childhood events, and then on to the behavioral crime addiction and criminal peers scales. Peer crime was also predicted by insecure parent attachments and the crime addiction scale. Finally, the crime addiction, peer crime, and insecure parental attachment scales predicted frequencies of criminal behavior. The model also fit a sample of 239 female inmates. The notions of crime addiction, in this context of adverse events and insecure parental attachments, offered newer and more powerful explanations than previously offered by social learning theories on why some individuals are more likely to associate with peers engaging in criminal behavior, and also how these combine to predict degrees of criminal behavior. By moving beyond main effects models, it was found that a focus on systems of interactions was robust in theory and application. However, profile data from the Attachment and Clinical Issues Questionnaire showed that individual differences in Research Domain Criteria diagnoses are fundamental to treatment settings. Such approaches to reducing rates of recidivism and substance abuse should also enhance outcomes in many domains, including HIV prevention, costs to health care, and at the same time increase overall public safety.

  5. Security for Network Attached Storage Devices

    National Research Council Canada - National Science Library

    Gobioff, Howard

    1997-01-01

    This paper presents a novel cryptographic capability system addressing the security and performance needs of network attached storage systems in which file management functions occur at a different...

  6. All that glitters is not gold: A projected distribution of the endemic Indian Golden Gecko Calodactylodes aureus (Reptilia: Squamata: Gekkonidae indicates a major range shrinkage due to future climate change.

    Directory of Open Access Journals (Sweden)

    Aditya Srinivasulu

    2016-06-01

    Full Text Available Climate change has a perceived threat on biodiversity due to its effect on species range.  Species with narrow ranges and highly specific climatic and habitat requirements are at higher risk.  To understand the influence of climate change on the Indian endemic gekkonid, the Indian Golden Gecko Calodactylodes aureus (Beddome, 1870 we model the present and future predicted distribution (2050 and 2070 under the CMIP5 RCP4.5 and RCP8.5 scenarios using MaxEnt under the HadGEM3-ES Model.  Our analysis revealed the negative impact of climate change on the Indian Golden Gecko with a decrease in the amount of climatically suitable areas in the future, and an almost total range shrinkage by 2070.  Despite its wide distribution in the eastern Deccan Peninsula, according to our predictions, the species is threatened by a shrinkage in the future range due to climate change. 

  7. A Network-Attached Storage System Supporting Guaranteed QoS

    Institute of Scientific and Technical Information of China (English)

    KONG Hua-feng; YU Sheng-sheng; LU Hong-wei

    2005-01-01

    We propose a network-attached storage system that can support guaranteed Quality of Service (QoS), called POPNet Storage. The special policy of date access and disk scheduling is enable users to access files quickly and directly with guaranteed QoS in the POPNet Storage. The POPNet Storage implements a measurement-based admission control algorithm (PSMBAC) to determine whether to admit a new data access request stream and admit as many requests as possible while meeting the QoS guarantees to its clients. The data reconstruction algorithms in the POPNet Storage also put more emphasis on data availability and guaranteed QoS, thus it is designed to complete the data recovery as soon as possible and at the same time provide the guaranteed QoS for high-priority data access. The experiment results show that the POPNet Storage can provide more significant performance, reliability, and guaranteed QoS than conventional storage systems.

  8. Lower fecundity in parthenogenetic geckos than sexual relatives in the Australian arid zone.

    Science.gov (United States)

    Kearney, M; Shine, R

    2005-05-01

    Theoretical models of the advantage of sexual reproduction typically assume that reproductive output is equal in sexual and parthenogenetic females. We tested this assumption by comparing fecundity between parthenogenetic and sexual races of gekkonid lizards in the Heteronotia binoei complex, collected across a 1200 km latitudinal gradient through the Australian arid zone. Under laboratory conditions, parthenogenetic geckos had approximately 30% lower fecundity when compared with their sexual progenitors, irrespective of body size. Reflecting clutch-size constraints in gekkonids, this fecundity difference was mainly because of fewer clutches over a shorter period. When parthenogens were compared more broadly with all coexisting sexual races across the latitudinal gradient, parthenogens had lower fecundity than sexuals only when corrected for body size. Differences in fecundity between parthenogens and coexisting sexual races depended on which sexual race was considered. There was no significant relationship between fecundity and parasite (mite) load, despite significantly higher mite loads in parthenogens than in sexual races.

  9. SLSF loop handling system. Volume III. AISC code evaluations and analysis of critical attachments

    International Nuclear Information System (INIS)

    Ahmed, H.; Cowie, A.; Malek, R.A.; Rafer, A.; Ma, D.; Tebo, F.

    1978-10-01

    SLSF loop handling system was analyzed for deadweight and postulated dynamic loading conditions using a linear elastic static equivalent method of stress analysis. Stress computations of Cradle and critical attachments per AISC Code guidelines are presented. HFEF is credited with in-depth review of initial phase of work

  10. 'Adoption and attachment theory' the attachment models of adoptive mothers and the revision of attachment patterns of their late-adopted children.

    Science.gov (United States)

    Pace, C S; Zavattini, G C

    2011-01-01

    This study examined the attachment patterns of late-adopted children (aged 4-7) and their adoptive mothers during the first 7- to 8-month period after adoption and aimed to evaluate the effect of adoptive mothers' attachment security on the revision of the attachment patterns of their late-adopted children. We assessed attachment patterns in 20 adoptive dyads and 12 genetically related dyads at two different times: T1 (time 1) within 2 months of adoption and T2 (time 2) 6 months after T1. The children's behavioural attachment patterns were assessed using the Separation-Reunion Procedure and the children's representational (verbal) attachment patterns using the Manchester Child Attachment Story Task. The attachment models of the adoptive mothers were classified using the Adult Attachment Interview. We found that there was a significant enhancement of the late-adopted children's attachment security across the time period considered (P= 0.008). Moreover, all the late-adopted children who showed a change from insecurity to security had adoptive mothers with secure attachment models (P= 0.044). However, the matching between maternal attachment models and late-adopted children's attachment patterns (behaviours and representations) was not significant. Our data suggest that revision of the attachment patterns in the late-adopted children is possible but gradual, and that the adoptive mothers' attachment security makes it more likely to occur. © 2010 Blackwell Publishing Ltd.

  11. Removable splint with locking attachments for maxillary distraction osteogenesis with the RED system.

    Science.gov (United States)

    Suzuki, E Y; Suzuki, B

    2007-12-01

    The external traction hooks of the intraoral splint used to control traction forces applied to the maxilla with the rigid external distraction system represent a major barrier to surgical procedures. The purpose of this article is to introduce a removable intraoral splint with locking attachments that can be placed post-surgically immediately before distraction, facilitating surgery and consequently reducing the operative time. Fifteen cleft lip and palate patients underwent maxillary distraction osteogenesis using a rigid external distraction device in combination with the proposed removable splint that was fixed onto the maxillary teeth to provide anchorage. Initial records showed severe maxillary hypoplasia and negative overjet. The removable splint was fabricated using 1.5-mm diameter stainless-steel rigid orthodontic wires soldered to the locking attachments (Y&B Products LP, Chiang Mai, Thailand), making possible its placement post-surgically. Stable splint fixation was achieved prior to the distraction procedure and the desired treatment goals were reached. No complications inserting or removing the splint post-surgically, including pain or discomfort, were observed. The use of the removable splint with locking attachments has proved to be a highly effective fixation approach to manage the severely hypoplastic maxilla, eliminating lip constraints resulting from scarring, and allowing for easier, more deliberate and careful dissection.

  12. Plasticity of thermoregulatory behavior in leopard geckos (Eublepharis macularius, Blyth 1954).

    Science.gov (United States)

    Craioveanu, Octavian; Craioveanu, Cristina; Mireşan, Vioara

    2017-07-01

    Studies on thermoregulation in nocturnal lizards have shown that their thermal regimes are similar to those of diurnal lizards, even though they hide during the daytime and are active mostly at night, when heat sources are very scarce. As a result, nocturnal lizards display an active thermoregulatory behavior consisting of seeking warm shelters to hide during the daytime, using accumulated heat for the nocturnal activity. Based on this information, we hypothesize that when leopard geckos (Eublepharis macularius, Blyth 1954) are presented with the choice of safety in cool shelters or vulnerability in heated open areas, suitable temperature will prevail in importance, i.e. they will trade the advantages provided by the shelter for an exposed, but physiologically necessary heat source. Data on the time juvenile E. macularius spent in shelters, and in open areas along a thermal gradient and under a 12/12 hr photoperiod, from eight individuals confirmed our hypothesis. We found that, not only did they select heat sources over shelters, but, along with the light/dark cycle, temperature may also represent a cue for activity. Additionally we found that substrate moisture plays an important role in shelter preference. © 2017 Wiley Periodicals, Inc.

  13. Reproductive tradeoffs and yolk steroids in female leopard geckos, Eublepharis macularius.

    Science.gov (United States)

    Rhen, T; Crews, D; Fivizzani, A; Elf, P

    2006-11-01

    Life history theory predicts tradeoffs among reproductive traits, but the physiological mechanisms underlying such tradeoffs remain unclear. Here we examine reproductive tradeoffs and their association with yolk steroids in an oviparous lizard. Female leopard geckos lay two eggs in a clutch, produce multiple clutches in a breeding season, and reproduce for several years. We detected a significant tradeoff between egg size and the number of clutches laid by females during their first two breeding seasons. Total reproductive effort was strongly condition-dependent in the first season, but much less so in the second season. Although these and other tradeoffs were unmistakable, they were not associated with levels of androstenedione, oestradiol, or testosterone in egg yolk. Female condition and egg size, however, were inversely related to dihydrotestosterone (DHT) levels in egg yolk. Finally, steroid levels in egg yolk were not directly related to steroid levels in the maternal circulation when follicles were developing, indicating that steroid transfer to eggs is regulated. These findings suggest that maternal allocation of DHT could mitigate tradeoffs that lead to poor offspring quality (i.e. poor female condition) and small offspring size (i.e. small egg size).

  14. The gecko visual pigments. The behavior of opsin.

    Science.gov (United States)

    Crescitelli, F

    1979-05-01

    The 521-pigment extracted out of the retina of the Tokay gecko has the typical stereospecificity of the vertebrate visual pigments. This is true for the pigment in the chloride-depleted, "blue-shifted" state as well as for the normal pigment with added chloride. While in the chloride-deficient state, pigment regeneration occurred with both 11-cis- and 9-cis-retinals and the regenerated photopigments were also in the blue-shifted, chloride-depleted state. As with the native pigment, these regenerated pigments were bathochromically shifted to their normal positions by the addition of chloride. Chloride-deficient opsin by itself also responded to chloride for the pigment regenerated with 11-cis-retinal from such chloride-treated opsin was in the normal 521-position. Regeneration was always rapid, reaching completion in less than 5 min, and was significantly faster than for cow rhodopsin regenerating under the same conditions. This rapid rate was found with or without chloride, with both 11-cis- and 9-cis-retinals and in the presence of the sulfhydryl poison, p-hydroxymercuribenzoate (PMB). Like the native chloride-deficient pigment, the regenerated chloride-depleted photopigments responded to PMB by a blue shift beyond the position of the chloride-deficient state. The addition of chloride to these "poisoned" regenerated pigments caused a bathochromic shift of such magnitude as to indicate a repair of both the PMB and chloride-deficient blue shift. In this discussion the possible implications of these results to phylogenetic considerations are considered as well as to some molecular properties of the 521-pigment.

  15. Blade attachment assembly

    Science.gov (United States)

    Garcia-Crespo, Andres Jose; Delvaux, John McConnell; Miller, Diane Patricia

    2016-05-03

    An assembly and method for affixing a turbomachine rotor blade to a rotor wheel are disclosed. In an embodiment, an adaptor member is provided disposed between the blade and the rotor wheel, the adaptor member including an adaptor attachment slot that is complementary to the blade attachment member, and an adaptor attachment member that is complementary to the rotor wheel attachment slot. A coverplate is provided, having a coverplate attachment member that is complementary to the rotor wheel attachment slot, and a hook for engaging the adaptor member. When assembled, the coverplate member matingly engages with the adaptor member, and retains the blade in the adaptor member, and the assembly in the rotor wheel.

  16. Variability of femoral muscle attachments.

    Science.gov (United States)

    Duda, G N; Brand, D; Freitag, S; Lierse, W; Schneider, E

    1996-09-01

    Analytical and experimental models of the musculoskeletal system often assume single values rather than ranges for anatomical input parameters. The hypothesis of the present study was that anatomical variability significantly influences the results of biomechanical analyses, specifically regarding the moment arms of the various thigh muscles. Insertions and origins of muscles crossing or attaching to the femur were digitized in six specimens. Muscle volumes were measured; muscle attachment area and centroid location were computed. To demonstrate the influence of inter-individual anatomic variability on a mechanical modeling parameter, the corresponding range of muscle moment arms were calculated. Standard deviations, as a percentage of the mean, were about 70% for attachment area and 80% for muscle volume and attachment centroid location. The resulting moment arms of the m. gluteus maximus and m. rectus femoris were especially sensitive to anatomical variations (SD 65%). The results indicate that sensitivity to anatomical variations should be analyzed in any investigation simulating musculoskeletal interactions. To avoid misinterpretations, investigators should consider using several anatomical configurations rather than relying on a mean data set.

  17. From secure dependency to attachment: Mary Ainsworth's integration of Blatz's security theory into Bowlby's attachment theory.

    Science.gov (United States)

    van Rosmalen, Lenny; van der Horst, Frank C P; van der Veer, René

    2016-02-01

    John Bowlby is generally regarded as the founder of attachment theory, with the help of Mary Ainsworth. Through her Uganda and Baltimore studies Ainsworth provided empirical evidence for attachment theory, and she contributed the notion of the secure base and exploratory behavior, the Strange Situation Procedure and its classification system, and the notion of maternal sensitivity. On closer scrutiny, many of these contributions appear to be heavily influenced by William Blatz and his security theory. Even though Blatz's influence on Ainsworth has been generally acknowledged, this article, partly based on understudied correspondence from several personal archives, is the first to show which specific parts of attachment theory can be traced back directly to Blatz and his security theory. When Ainsworth started working with Bowlby in the 1950s, around the time he turned to evolutionary theory for an explanation of his findings, she integrated much of Blatzian security theory into Bowlby's theory in the making and used her theoretical and practical experience to enrich attachment theory. Even though Blatz is hardly mentioned nowadays, several of his ideas live on in attachment theory. (c) 2016 APA, all rights reserved).

  18. Anorexia and Attachment: Dysregulated Defense and Pathological Mourning

    Directory of Open Access Journals (Sweden)

    elisa edelvecchio

    2014-10-01

    Full Text Available The role of Defensive exclusion (Deactivation and Segregated Systems in the development of early relationships and related to subsequent manifestations of symptoms of eating disorders was assessed using the Adult Attachment Projective Picture System (AAP. Fifty-one DSM-IV diagnosed women with anorexia participated in the study. Anorexic patients were primarily classified as dismissing or unresolved. Quantitative and qualitative analyses of defensive exclusion were carried out. Results showed potential benefits of using the AAP defense exclusion coding system, in addition to the main attachment classifications, in order to better understand the developmental issues involved in anorexia. Discussion concerned the processes, such as pathological mourning, that may underlie the associations between dismissing and unresolved attachment and anorexia. Implications for developmental research and clinical nosology are discussed.

  19. Do Tick Attachment Times Vary between Different Tick-Pathogen Systems?

    Directory of Open Access Journals (Sweden)

    Stephanie L. Richards

    2017-05-01

    Full Text Available Improvements to risk assessments are needed to enhance our understanding of tick-borne disease epidemiology. We review tick vectors and duration of tick attachment required for pathogen transmission for the following pathogens/toxins and diseases: (1 Anaplasma phagocytophilum (anaplasmosis; (2 Babesia microti (babesiosis; (3 Borrelia burgdorferi (Lyme disease; (4 Southern tick-associated rash illness; (5 Borrelia hermsii (tick-borne relapsing fever; (6 Borrelia parkeri (tick-borne relapsing fever; (7 Borrelia turicatae (tick-borne relapsing fever; (8 Borrelia mayonii; (9 Borrelia miyamotoi; (10 Coxiella burnetii (Query fever; (11 Ehrlichia chaffeensis (ehrlichiosis; (12 Ehrlichia ewingii (ehrlichiosis; (13 Ehrlichia muris; (14 Francisella tularensis (tularemia; (15 Rickettsia 364D; (16 Rickettsia montanensis; (17 Rickettsia parkeri (American boutonneuse fever, American tick bite fever; (18 Rickettsia ricketsii (Rocky Mountain spotted fever; (19 Colorado tick fever virus (Colorado tick fever; (20 Heartland virus; (21 Powassan virus (Powassan disease; (22 tick paralysis neurotoxin; and (23 Galactose-α-1,3-galactose (Mammalian Meat Allergy-alpha-gal syndrome. Published studies for 12 of the 23 pathogens/diseases showed tick attachment times. Reported tick attachment times varied (<1 h to seven days between pathogen/toxin type and tick vector. Not all studies were designed to detect the duration of attachment required for transmission. Knowledge of this important aspect of vector competence is lacking and impairs risk assessment for some tick-borne pathogens.

  20. Electron-attachment processes

    International Nuclear Information System (INIS)

    Christophorou, L.G.; McCorkle, D.L.; Christodoulides, A.A.

    1982-01-01

    Topics covered include: (1) modes of production of negative ions, (2) techniques for the study of electron attachment processes, (3) dissociative electron attachment to ground-state molecules, (4) dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), (5) molecular parent negative ions, and (6) negative ions formed by ion-pair processes and by collisions of molecules with ground state and Rydberg atoms

  1. Arachnids secrete a fluid over their adhesive pads.

    Directory of Open Access Journals (Sweden)

    Anne M Peattie

    Full Text Available BACKGROUND: Many arachnids possess adhesive pads on their feet that help them climb smooth surfaces and capture prey. Spider and gecko adhesives have converged on a branched, hairy structure, which theoretically allows them to adhere solely by dry (solid-solid intermolecular interactions. Indeed, the consensus in the literature is that spiders and their smooth-padded relatives, the solifugids, adhere without the aid of a secretion. METHODOLOGY AND PRINCIPAL FINDINGS: We investigated the adhesive contact zone of living spiders, solifugids and mites using interference reflection microscopy, which allows the detection of thin liquid films. Like insects, all the arachnids we studied left behind hydrophobic fluid footprints on glass (mean refractive index: 1.48-1.50; contact angle: 3.7-11.2°. Fluid was not always secreted continuously, suggesting that pads can function in both wet and dry modes. We measured the attachment forces of single adhesive setae from tarantulas (Grammostola rosea by attaching them to a bending beam with a known spring constant and filming the resulting deflection. Individual spider setae showed a lower static friction at rest (26%±2.8 SE of the peak friction than single gecko setae (Thecadactylus rapicauda; 96%±1.7 SE. This may be explained by the fact that spider setae continued to release fluid after isolation from the animal, lubricating the contact zone. SIGNIFICANCE: This finding implies that tarsal secretions occur within all major groups of terrestrial arthropods with adhesive pads. The presence of liquid in an adhesive contact zone has important consequences for attachment performance, improving adhesion to rough surfaces and introducing rate-dependent effects. Our results leave geckos and anoles as the only known representatives of truly dry adhesive pads in nature. Engineers seeking biological inspiration for synthetic adhesives should consider whether model species with fluid secretions are appropriate to their

  2. Remote handling assessment of attachment concepts for DEMO blanket segments

    Energy Technology Data Exchange (ETDEWEB)

    Iglesias, Daniel, E-mail: daniel.iglesias@ccfe.ac.uk [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Bastow, Roger; Cooper, Dave; Crowe, Robert; Middleton-Gear, Dave [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Sibois, Romain [VTT, Technical Research Centre of Finland, Industrial Systems, ROViR, Tampere (Finland); Carloni, Dario [Institute of Neutron Physics and Reactor Technology, Karlsruhe Institute of Technology (KIT) (Germany); Vizvary, Zsolt; Crofts, Oliver [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom); Harman, Jon [EFDA Close Support Unit Garching, Boltzmannstaße 2, D-85748 Garching bei München (Germany); Loving, Antony [CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB (United Kingdom)

    2015-10-15

    Highlights: • Challenges are identified for the remote handling of blanket segments’ attachments. • Two attachment design approaches are assessed for remote handling (RH) feasibility. • An alternative is proposed, which potentially simplifies and speeds-up RH operations. • Up to three different assemblies are proposed for the remote handling of the attachments. • Proposed integrated design of upper port is compatible with the attachment systems. - Abstract: The replacement strategy of the massive Multi-Module Blanket Segments (MMS) is a key driver in the design of several DEMO systems. These include the blankets themselves, the vacuum vessel (VV) and its ports and the Remote Maintenance System (RMS). Common challenges to any blanket attachment system have been identified, such as the need for applying a preload to the MMS manifold, the effects of the decay heat and several uncertainties related to permanent deformations when removing the blanket segments after service. The WP12 kinematics of the MMS in-vessel transportation was adapted to the requirements of each of the supports during 2013 and 2014 design activities. The RM equipment envisaged for handling attachments and earth connections may be composed of up to three different assemblies. An In-Vessel Mover at the divertor level handles the lower support and earth bonding, and could stabilize the MMS during transportation. A Shield Plug crane with a 6 DoF manipulator operates the upper attachment and earth straps. And a Vertical Maintenance Crane is responsible for the in-vessel MMS transportation and can handle the removable upper support pins. A final proposal is presented which can potentially reduce the number of required systems, at the same time that speeds-up the RMS global operations.

  3. Cohesion-decohesion asymmetry in geckos

    Science.gov (United States)

    Puglisi, G.; Truskinovsky, L.

    2013-03-01

    Lizards and insects can strongly attach to walls and then detach applying negligible additional forces. We propose a simple mechanical model of this phenomenon which implies active muscle control. We show that the detachment force may depend not only on the properties of the adhesive units, but also on the elastic interaction among these units. By regulating the scale of such cooperative interaction, the organism can actively switch between two modes of adhesion: delocalized (pull off) and localized (peeling).

  4. Scented guide ropes as a method to enhance brown treesnake (Boiga irregularis) trap capture success on Guam

    Science.gov (United States)

    Mason, L.C.; Savidge, J.A.; Rodda, G.H.; Yackel Adams, A.A.

    2011-01-01

    Current methods for controlling the invasive Brown Treesnake (Boiga irregularis) on Guam include a modified minnow trap with a live mouse lure. We investigated the effects on capture success of augmenting these traps with scented guide ropes leading to trap entrances. Initial screening of scent preferences was based on time spent in scented and unscented arms of a Y-maze. Preferences of large and small snakes were scored for six different prey scents (live and carrion gecko, skink, and mouse). Large snakes spent more time in the maze arm scented with live gecko and carrion gecko, whereas small snakes spent more time in the arm scented with carrion mouse and carrion gecko. After the laboratory study, a pilot trapping session was conducted in the field using three treatments (live mouse-scented ropes, carrion gecko-scented ropes, and carrion mouse-scented ropes) and two controls (traps with unscented guide ropes and those with no ropes attached). Contrary to laboratory results, live mouse-scented ropes were most effective. We conducted a second trapping session using live mouse-scented ropes as well as the two controls used in the pilot study. For snakes of below-average to average condition, the number of captures for traps with live mouse-scented ropes was higher than for traps with no ropes. However, for snakes of above-average condition, there were no differences in capture rates between trap treatments. Overall, treatment effects were weaker than latent individual heterogeneity and the influence of snake body size, with large snakes trapped more readily. ?? 2011 Society for the Study of Amphibians and Reptiles.

  5. Effects of the Adult Attachment Projective Picture System on oxytocin and cortisol blood levels in mothers

    Directory of Open Access Journals (Sweden)

    Sabrina Krause

    2016-12-01

    Full Text Available Oxytocin, a small neuropeptide of nine amino acids, has been characterized as the hormone of affiliation and is stimulated, for instance, in mothers when interacting with their offspring. Variations in maternal oxytocin levels were reported to predict differences in the quality of care provided by mothers. In this study, the Adult Attachment Projective Picture System (AAP as a valid measure to assess attachment representations was used as an activating attachment-related stimulus. We investigated whether the AAP induces a release of oxytocin in mothers with a secure attachment representation and a stress-related cortisol response in mothers with an insecure attachment representation. Therefore, pre-post effects of AAP administration on plasma oxytocin and serum cortisol levels were investigated in n = 44 mothers 3 months after parturition. Oxytocin levels increased from pre to post by the significant majority of 73% participants (p = .004 and cortisol decreased by the significant majority of 73% participants (p = .004. Interestingly, no association between alterations in oxytocin and cortisol were found; this suggests taking a model of two independent processes into considerations. These results show that the AAP test procedure induces an oxytocin response. Concerning the results within the four AAP representation subgroups, our hypothesis of a particularly strong increase in oxytocin in secure mothers was not confirmed; however, in secure mothers we observed a particularly strong decrease in cortisol, consistent with our hypotheses. Effect sizes are reported, allowing the replication of results in a larger study with sufficient sample size to draw final conclusions with respect to differences in OT and cortisol alterations depending on attachment representation. When interpreting the results, one should keep in mind that this study investigated lactating mothers. Thus, the generalizability of results is limited and future studies should

  6. Effects of the Adult Attachment Projective Picture System on Oxytocin and Cortisol Blood Levels in Mothers.

    Science.gov (United States)

    Krause, Sabrina; Pokorny, Dan; Schury, Katharina; Doyen-Waldecker, Cornelia; Hulbert, Anna-Lena; Karabatsiakis, Alexander; Kolassa, Iris-Tatjana; Gündel, Harald; Waller, Christiane; Buchheim, Anna

    2016-01-01

    Oxytocin, a small neuropeptide of nine amino acids, has been characterized as the "hormone of affiliation" and is stimulated, for instance, in mothers when interacting with their offspring. Variations in maternal oxytocin levels were reported to predict differences in the quality of care provided by mothers. In this study, the Adult Attachment Projective Picture System (AAP) as a valid measure to assess attachment representations was used as an activating attachment-related stimulus. We investigated whether the AAP induces a release of oxytocin in mothers with a secure attachment representation and a stress-related cortisol response in mothers with an insecure attachment representation. Therefore, pre-post effects of AAP administration on plasma oxytocin and serum cortisol levels were investigated in n = 44 mothers 3 months after parturition. Oxytocin levels increased from pre to post in the significant majority of 73% participants ( p = 0.004) and cortisol decreased in the significant majority of 73% participants ( p = 0.004). Interestingly, no association between alterations in oxytocin and cortisol were found; this suggests taking a model of two independent processes into considerations. These results show that the AAP test procedure induces an oxytocin response. Concerning the results within the four AAP representation subgroups, our hypothesis of a particularly strong increase in oxytocin in secure mothers was not confirmed; however, in secure mothers we observed a particularly strong decrease in cortisol. Effect sizes are reported, allowing the replication of results in a larger study with sufficient sample size to draw final conclusions with respect to differences in OT and cortisol alterations depending on attachment representation. When interpreting the results, one should keep in mind that this study investigated lactating mothers. Thus, the generalizability of results is limited and future studies should investigate non-lactating healthy females as well

  7. Attachment and social networks.

    Science.gov (United States)

    Gillath, Omri; C Karantzas, Gery; Lee, Juwon

    2018-02-21

    The current review covers two lines of research linking attachment and social networks. One focuses on attachment networks (the people who fulfill one's attachment needs), examining composition and age-related differences pertaining to these networks. The other line integrates attachment with social network analysis to investigate how individual differences in adult attachment are associated with the management and characteristics (e.g., density, multiplexity, and centrality) of people's social networks. We show that most people's attachment networks are small and hierarchical, with one figure being the primary attachment figure (often a mother or romantic partner, depending on age). Furthermore, attachment style predicts network characteristics and management, such that insecurity is associated with less closeness, multiplexity, centrality, and poorer management (less maintenance, more dissolution). Copyright © 2018 Elsevier Ltd. All rights reserved.

  8. Viii. Attachment and sleep among toddlers: disentangling attachment security and dependency.

    Science.gov (United States)

    Bélanger, Marie-Ève; Bernier, Annie; Simard, Valérie; Bordeleau, Stéphanie; Carrier, Julie

    2015-03-01

    Many scholars have proposed that parent-child attachment security should favor child sleep. Research has yet, however, to provide convincing support for this hypothesis. The current study used objective measures of sleep and attachment to assess the longitudinal links between mother-child attachment security and subsequent sleep, controlling for child dependency. Sixty-two middle-class families (30 girls) were met twice, when children were 15 months (Wave 1; W1) and 2 years of age (Wave 2; W2). At W1, mother-child attachment was assessed with the observer version of the Attachment Q-Sort. At W2, children wore an actigraph monitor for 72 hr. Results indicated that children more securely attached to their mothers subsequently slept more at night and had higher sleep efficiency, and these predictions were not confounded by child dependency. These findings suggest a unique role for secure attachment relationships in the development of young children's sleep regulation, while addressing methodological issues that have long precluded consensus in this literature. © 2015 The Society for Research in Child Development, Inc.

  9. Attachment Theory in Tourism

    Directory of Open Access Journals (Sweden)

    Maximiliano Korstanje

    2007-01-01

    Full Text Available The following work is intended to a revision on attachment theory. The postulates of the theory of the sure base point that the system of exploration meets in narrow relation the system of conducts of attachment and the figure of the keepers. The conducts that characterize and symbolize the relation of the adult with the environment are carried back to the early age, in the moment in which the child develops the affective capacity. What difference does exist between someone who decides to journey to England and that one that one decides to travel to Mar del Plata? How it is possible to study this topic of on a manner trustworthy? These three questions were key to begin the investigation. Nevertheless, the matter began to find certain limitations linked to the methodology that had to be in use. It is possible to use careless they on the leisure scope, a theory which still demonstrates certain inconsistencies in its own clinical application?

  10. An experimental evaluation of the State Adult Attachment Measure: The Influence of Attachment Primes on the Content of State Attachment Representations

    OpenAIRE

    Bosmans, Guy; Bowles, David, P.; Dewitte, Marieke; De Winter, Simon; Braet, Caroline

    2014-01-01

    Attachment theory predicts cross-contextual stability of attachment representations, but research findings are rather mixed. Recently, it has been suggested that these mixed findings reflect the existence of both state and trait attachment components. The development of the State Adult Attachment Measure (SAAM) has enabled an investigation of this hypothesis. The current study aimed to evaluate the extent to which the SAAM is a useful instrument for studying such state attachment hypotheses. ...

  11. Attachment over Time.

    Science.gov (United States)

    Lewis, Michael; Feiring, Candice; Rosenthal, Saul

    2000-01-01

    Examined continuity in attachment classification from infancy through adolescence and related it to autobiographical memories of childhood, divorce, and maladjustment in white middle-class children. Found no continuity in attachment classification from 1 to 18 years and no relation between infant attachment status and adolescent adjustment.…

  12. Developing a reliable signal wire attachment method for rail.

    Science.gov (United States)

    2014-11-01

    The goal of this project was to develop a better attachment method for rail signal wires to improve the reliability of signaling : systems. EWI conducted basic research into the failure mode of current attachment methods and developed and tested a ne...

  13. The neural correlates of attachment security in typically developing children.

    Science.gov (United States)

    Choi, Eun Jung; Taylor, Margot J; Hong, Soon-Beom; Kim, Changdai; Yi, Soon-Hyung

    2018-07-01

    This study investigated neural correlates of children's attachment security using functional magnetic resonance imaging. Fifty-one boys' attachment styles (age mean = 9.5 years, SD = 0.61) were assessed with the Separation Anxiety Test (SAT). We created an fMRI version of the SAT to activate children's attachment system in fMRI environment and contrasted two conditions in which children were instructed to infer the specific feeling of the boy in the picture or to identify objects or physical activities. In the final fMRI analysis (N = 21), attachment security could be detected at the neural level corresponding to the behavioural differences in the attachment interview. Securely attached children showed greater activation in the frontal, limbic and basal ganglia area which included the dorsolateral prefrontal cortex, amygdala, cingulate cortex and striatum, compared to other children who had lower quality of attachment. These regions have a key role in socio-emotional information processing and also represent a brain network related to approach and avoidance motivation in humans. Especially the striatum, strongly linked to reward processing underpinning social approach and avoidance motivation, showed the largest effects in these differences and also positively correlated with emotional openness scores in SAT. This suggests that the quality of attachment configures the approach and avoidance motivational system in our brain mediated by the striatum. Copyright © 2018 Elsevier Inc. All rights reserved.

  14. A comparison of anesthetic agents and their effects on the response properties of the peripheral auditory system.

    Science.gov (United States)

    Dodd, F; Capranica, R R

    1992-10-01

    Anesthetic agents were compared in order to identify the most appropriate agent for use during surgery and electrophysiological recordings in the auditory system of the tokay gecko (Gekko gecko). Each agent was first screened for anesthetic and analgesic properties and, if found satisfactory, it was subsequently tested in electrophysiological recordings in the auditory nerve. The following anesthetic agents fulfilled our criteria and were selected for further screening: sodium pentobarbital (60 mg/kg); sodium pentobarbital (30 mg/kg) and oxymorphone (1 mg/kg); 3.2% isoflurane; ketamine (440 mg/kg) and oxymorphone (1 mg/kg). These agents were subsequently compared on the basis of their effect on standard response properties of auditory nerve fibers. Our results verified that different anesthetic agents can have significant effects on most of the parameters commonly used in describing the basic response properties of the auditory system in vertebrates. We therefore conclude from this study that the selection of an appropriate experimental protocol is critical and must take into consideration the effects of anesthesia on auditory responsiveness. In the tokay gecko, we recommend 3.2% isoflurane for general surgical procedures; and for electrophysiological recordings in the eighth nerve we recommend barbiturate anesthesia of appropriate dosage in combination if possible with an opioid agent to provide additional analgesic action.

  15. BEWARE OF OPENING ATTACHMENTS IN E-MAIL

    CERN Multimedia

    2000-01-01

    Following the recent e-mail viruses you are asked to be cautious when opening e-mail attachments on your PC. Attachments that are apparently harmless might hide active content producing nasty effects as soon as they are opened. Some of these so called 'Trojan horses' can conceal themselves in very attractive pictures and funny slide shows.On the PC Windows infrastructure, CERN runs software to protect users from known viruses, but new ones can sometimes arrive before our software recognises them. They can enter your system when you open an attachment. To remove them it may be necessary to re-install the Windows software on your PC.

  16. Attachment behavior of fission products to solution aerosol

    Energy Technology Data Exchange (ETDEWEB)

    Takamiya, Koichi; Tanaka, Toru; Nitta, Shinnosuke; Itosu, Satoshi; Sekimoto, Shun; Oki, Yuichi; Ohtsuki, Tsutomu [Research Reactor Institute, Kyoto University, Osaka (Japan)

    2016-12-15

    Various characteristics such as size distribution, chemical component and radioactivity have been analyzed for radioactive aerosols released from Fukushima Daiichi Nuclear Power Plant. Measured results for radioactive aerosols suggest that the potential transport medium for radioactive cesium was non-sea-salt sulfate. This result indicates that cesium isotopes would preferentially attach with sulfate compounds. In the present work the attachment behavior of fission products to aqueous solution aerosols of sodium salts has been studied using a generation system of solution aerosols and spontaneous fission source of {sup 248}Cm. Attachment ratios of fission products to the solution aerosols were compared among the aerosols generated by different solutions of sodium salt. A significant difference according as a solute of solution aerosols was found in the attachment behavior. The present results suggest the existence of chemical effects in the attachment behavior of fission products to solution aerosols.

  17. Attachment and Chronic Pain in Children and Adolescents

    Directory of Open Access Journals (Sweden)

    Theresa J. Donnelly

    2016-10-01

    Full Text Available Although attachment theory is not new, its theoretical implications for the pediatric chronic pain context have not been thoroughly considered, and the empirical implications and potential clinical applications are worth exploring. The attachment framework broadly focuses on interactions between a child’s developing self-regulatory systems and their caregiver’s responses. These interactions are believed to create a template for how individuals will relate to others in the future, and may help account for normative and pathological patterns of emotions and behavior throughout life. This review outlines relevant aspects of the attachment framework to the pediatric chronic pain context. The theoretical and empirical literature is reviewed regarding the potential role of attachment-based constructs such as vulnerability and maintaining factors of pediatric chronic pain. The nature and targets of attachment-based pediatric interventions are considered, with particular focus on relevance for the pediatric chronic pain context. The potential role of attachment style in the transition from acute to chronic pain is considered, with further research directions outlined.

  18. The use of attachment theory in the clinical dialogue with patients.

    Science.gov (United States)

    Cortina, Mauricio

    2013-01-01

    Attachment theory specifically addresses the ability to use an attachment figure as a haven of safety and base of exploration. While many other relational issues are important during development, a foundation of trust based on having positive expectations that others will be available when needed is clearly relevant in the practice of psychotherapy. Yet many patients come in with histories of insecure or even disorganized attachment and have suffered different forms of maltreatment. Understanding affect-regulating strategies, defensive processes, and transference and countertransference patterns associated with insecure or disorganized patterns is enormously useful during the clinical exchange. In addition to paying attention to affect regulation strategies, it is important to note that two other motivational systems may become coopted for defensive purposes in order to cope with disorganized attachment: the caregiving system and the ranking system (the latter being the legacy of dominance hierarchies we observe in primates). The other theme in this article is the importance of paying attention to a cooperative and social engagement motivational system (sometimes referred sometimes to as a social or affiliative motive) in building a therapeutic alliance. This prosocial motive is not about safety (attachment) but about sharing and developing positive social relations with others (Cortina & Liotti, 2010). The article explores the significance of building on this cooperative and social engagement system when there is not a foundation of trust based on a secure attachment history.

  19. Formal Mentoring Relationships and Attachment Theory: Implications for Human Resource Development

    Science.gov (United States)

    Germain, Marie-Line

    2011-01-01

    An attachment theory perspective of mentoring is presented to explain the degree of functionality of a mentor-protege formal match in an organizational setting. By focusing on Bowlby's (1969/1982) behavioral system of attachment and its triarchic taxonomy of secure, avoidant, and anxious-ambivalent attachment, previous conceptualizations are…

  20. The Female Reproductive Cycle of the Bedriaga Plate-Tailed Gecko, Teratoscincus bedriagai (Sauria: Gekkonidae in Iran

    Directory of Open Access Journals (Sweden)

    Fatemeh Mojibi

    2014-01-01

    Full Text Available The Bedriaga Plate-tailed Gecko, Teratoscincus bedriagai Nikolsky, 1900, is distributed in the northern and eastern desert basins of the Central Plateau of Iran, Sistan, and the desert regions of southern Afghanistan. Iranian specimens are believed to be rare in collections. In this study, the reproductive cycle of this species has been investigated through focusing on oogenesis from 5 April to 5 August, 2013. Generally, 15 adult females were collected by hand at midnight from southern parts of Damghan County, situated in Semnan Province of Iran. Ovaries were removed and processed for the purpose of histological and morphometric studies. The results revealed that oocyte growth starts in early April and terminates in late July. Moreover, mating commences in spring, especially at the beginning of May, with oviposition occurring from late May to late July. Approximately, 1 to 2 eggs are laid by females per clutch with the possibility of producing a secondary clutch later in the season. The maximum reproductive activity takes place in May and continues with a decreasing trend in June and more reduction in July and finally ends in August. No significant difference was observed between right and left side of reproductive system. Therefore, oogenesis occurs from April to July, while T. bedriagai follows an oogenic cycle typical for temperate species.

  1. Infant attachment, adult attachment, and maternal sensitivity: revisiting the intergenerational transmission gap.

    Science.gov (United States)

    Behrens, Kazuko Y; Haltigan, John D; Bahm, Naomi I Gribneau

    2016-08-01

    This study investigated the intergenerational transmission of attachment, utilizing the Adult Attachment Interview (AAI), the Strange Situation Procedure (SSP), and the Maternal Behavioral Q-Set (MBQS). We revisited fundamental questions in attachment theory and research by examining: (1) the level of intergenerational agreement between maternal attachment representations and infant attachment security, and (2) whether maternal sensitivity serves as an intergenerational mediator between adult and infant attachment security. Significant categorical matches between the AAI and the SSP as well as mean differences for MBQS scores between adult attachment secure-insecure groups were found. Consistent with earlier intergenerational research, maternal sensitivity only partially mediated the AAI-SSP link, indicating the transmission gap remains. Consistent with recent mediation studies, using more contemporary analytical techniques, it was confirmed that maternal sensitivity did mediate the direct pathway between AAI security and SSP security. Thus, the transmission gap appears somewhat different depending on the statistical method used to measure mediation. Post hoc analyses considered mothers' childhood experiences of separation/divorce and this helped make sense of intergenerational mismatches.

  2. R and D contract management systems in the USA (Attachment); Beikoku ni okeru R and D contract kanri system (tenpu shiryohen)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-02-01

    Presented herein is the attachment for 'R and D contract management systems in the USA'. The major contents include regulations governing the R and D contracts, procedures for the R and D contracts, financial procedures for the R and D contracts, procedures for the alternative R and D contracts, financial management of the R and D contracts, and activities for the management of the contract processes by electronic systems. (NEDO)

  3. Attachment and children's biased attentional processing: evidence for the exclusion of attachment-related information.

    Directory of Open Access Journals (Sweden)

    Eva Vandevivere

    Full Text Available Research in both infants and adults demonstrated that attachment expectations are associated with the attentional processing of attachment-related information. However, this research suffered from methodological issues and has not been validated across ages. Employing a more ecologically valid paradigm to measure attentional processes by virtue of eye tracking, the current study tested the defensive exclusion hypothesis in late childhood. According to this hypothesis, insecurely attached children are assumed to defensively exclude attachment-related information. We hypothesized that securely attached children process attachment- related neutral and emotional information in a more open manner compared to insecurely attached children. Sixty-two children (59.7% girls, 8-12 years completed two different tasks, while eye movements were recorded: task one presented an array of neutral faces including mother and unfamiliar women and task two presented the same with happy and angry faces. Results indicated that more securely attached children looked longer at mother's face regardless of the emotional expression. Also, they tend to have more maintained attention to mother's neutral face. Furthermore, more attachment avoidance was related to a reduced total viewing time of mother's neutral, happy, and angry face. Attachment anxiety was not consistently related to the processing of mother's face. Findings support the theoretical assumption that securely attached children have an open manner of processing all attachment-related information.

  4. Fabrication of an artificial nanosucker device with a large area nanotube array of metallic glass.

    Science.gov (United States)

    Chen, Wei-Ting; Manivannan, Karthikeyan; Yu, Chia-Chi; Chu, Jinn P; Chen, Jem-Kun

    2018-01-18

    The concurrent attachment and detachment movements of geckos on virtually any type of surface via their foot pads have inspired us to develop a thermal device with numerous arrangements of a multi-layer thin film together with electrodes that can help modify the temperature of the surface via application of a voltage. A sequential fabrication process was employed on a large-scale integration to generate well-defined contact hole arrays of photoresist for use as templates on the electrode-based device. The photoresist templates were then subjected to sputter deposition of the metallic glass Zr 55 Cu 30 Al 10 Ni 5 . Consequently, a metallic glass nanotube (MGNT) array having a nominal wall thickness of 100 nm was obtained after removal of the photoresist template. When a water droplet was placed on the MGNT array, close nanochambers of metallic glass were formed. By applying voltage, the surface was heated to increase the pressure inside the nanochambers; this generated an expanding force that raised the droplet; thus, the static water contact angle (SWCA) was increased. In contrast, a sucking force was generated during surface cooling, which decreased the SWCA. Our fabrication strategy exploits the MGNT array surface as nanosuckers, which can mimic the climbing aptitude of geckos as they attach to (>10 N m -2 ) and detach from (0.26 N m -2 ) surfaces at 0.5 and 3 V of applied voltage, respectively. Thus, the climbing aptitude of geckos can be mimicked by employing the processing strategy presented herein for the development of artificial foot pads.

  5. There's more than one way to climb a tree: Limb length and microhabitat use in lizards with toe pads.

    Science.gov (United States)

    Hagey, Travis J; Harte, Scott; Vickers, Mathew; Harmon, Luke J; Schwarzkopf, Lin

    2017-01-01

    Ecomorphology links microhabitat and morphology. By comparing ecomorphological associations across clades, we can investigate the extent to which evolution can produce similar solutions in response to similar challenges. While Anolis lizards represent a well-studied example of repeated convergent evolution, very few studies have investigated the ecomorphology of geckos. Similar to anoles, gekkonid lizards have independently evolved adhesive toe pads and many species are scansorial. We quantified gecko and anole limb length and microhabitat use, finding that geckos tend to have shorter limbs than anoles. Combining these measurements with microhabitat observations of geckos in Queensland, Australia, we observed geckos using similar microhabitats as reported for anoles, but geckos with relatively longer limbs were using narrower perches, differing from patterns observed in anoles and other lizards. We also observed arboreal geckos with relatively shorter proximal limb segments as compared to rock-dwelling and terrestrial geckos, similar to patterns observed for other lizards. We conclude that although both geckos and anoles have adhesive pads and use similar microhabitats, their locomotor systems likely complement their adhesive pads in unique ways and result in different ecomorphological patterns, reinforcing the idea that species with convergent morphologies still have idiosyncratic characteristics due to their own separate evolutionary histories.

  6. There’s more than one way to climb a tree: Limb length and microhabitat use in lizards with toe pads

    Science.gov (United States)

    Harte, Scott; Vickers, Mathew; Harmon, Luke J.; Schwarzkopf, Lin

    2017-01-01

    Ecomorphology links microhabitat and morphology. By comparing ecomorphological associations across clades, we can investigate the extent to which evolution can produce similar solutions in response to similar challenges. While Anolis lizards represent a well-studied example of repeated convergent evolution, very few studies have investigated the ecomorphology of geckos. Similar to anoles, gekkonid lizards have independently evolved adhesive toe pads and many species are scansorial. We quantified gecko and anole limb length and microhabitat use, finding that geckos tend to have shorter limbs than anoles. Combining these measurements with microhabitat observations of geckos in Queensland, Australia, we observed geckos using similar microhabitats as reported for anoles, but geckos with relatively longer limbs were using narrower perches, differing from patterns observed in anoles and other lizards. We also observed arboreal geckos with relatively shorter proximal limb segments as compared to rock-dwelling and terrestrial geckos, similar to patterns observed for other lizards. We conclude that although both geckos and anoles have adhesive pads and use similar microhabitats, their locomotor systems likely complement their adhesive pads in unique ways and result in different ecomorphological patterns, reinforcing the idea that species with convergent morphologies still have idiosyncratic characteristics due to their own separate evolutionary histories. PMID:28953920

  7. There's more than one way to climb a tree: Limb length and microhabitat use in lizards with toe pads.

    Directory of Open Access Journals (Sweden)

    Travis J Hagey

    Full Text Available Ecomorphology links microhabitat and morphology. By comparing ecomorphological associations across clades, we can investigate the extent to which evolution can produce similar solutions in response to similar challenges. While Anolis lizards represent a well-studied example of repeated convergent evolution, very few studies have investigated the ecomorphology of geckos. Similar to anoles, gekkonid lizards have independently evolved adhesive toe pads and many species are scansorial. We quantified gecko and anole limb length and microhabitat use, finding that geckos tend to have shorter limbs than anoles. Combining these measurements with microhabitat observations of geckos in Queensland, Australia, we observed geckos using similar microhabitats as reported for anoles, but geckos with relatively longer limbs were using narrower perches, differing from patterns observed in anoles and other lizards. We also observed arboreal geckos with relatively shorter proximal limb segments as compared to rock-dwelling and terrestrial geckos, similar to patterns observed for other lizards. We conclude that although both geckos and anoles have adhesive pads and use similar microhabitats, their locomotor systems likely complement their adhesive pads in unique ways and result in different ecomorphological patterns, reinforcing the idea that species with convergent morphologies still have idiosyncratic characteristics due to their own separate evolutionary histories.

  8. Shunt attachment and method for interfacing current collection systems

    Science.gov (United States)

    Denney, Paul E.; Iyer, Natraj C.; Hannan, III, William F.

    1992-01-01

    A composite brush to shunt attachment wherein a volatile component of a composite but mostly metallic brush, used for current collection purposes, does not upon welding or brazing, adversely affect the formation of the interfacial bond with a conductive shunt which carries the current from the zone of the brush. The brush to shunt attachment for a brush material of copper-graphite composite and a shunt of copper, or substituting silver for copper as an alternative, is made through a hot isostatic pressing (HIP). The HIP process includes applying high pressure and temperature simultaneously at the brush to shunt interface, after it has been isolated or canned in a metal casing in which the air adjacent to the interface has been evacuated and the interfacial area has been sealed before the application of pressure and temperature.

  9. Direct integration of MEMS, dielectric pumping and cell manipulation with reversibly bonded gecko adhesive microfluidics

    International Nuclear Information System (INIS)

    Warnat, S; King, H; Hubbard, T; Wasay, A; Sameoto, D

    2016-01-01

    We present an approach to form a microfluidic environment on top of MEMS dies using reversibly bonded microfluidics. The reversible polymeric microfluidics moulds bond to the MEMS die using a gecko-inspired gasket architecture. In this study the formed microchannels are demonstrated in conjunction with a MEMS mechanical single cell testing environment for BioMEMS applications. A reversible microfluidics placement technique with an x - y and rotational accuracy of  ±2 µ m and 1° respectively on a MEMS die was developed. No leaks were observed during pneumatic pumping of common cell media (PBS, sorbitol, water, seawater) through the fluidic channels. Thermal chevron actuators were successful operated inside this fluidic environment and a performance deviation of ∼15% was measured compared to an open MEMS configuration. Latex micro-spheres were pumped using traveling wave di-electrophoresis and compared to an open (no-microfluidics) configuration with velocities of 24 µ m s −1 and 20 µ m s −1 . (technical note)

  10. The Attachment Imperative

    DEFF Research Database (Denmark)

    Navne, Laura Emdal; Svendsen, Mette Nordahl; Gammeltoft, Tine

    2017-01-01

    on social relations and point to the productive aspects of practices of distance and detachment. We show that while the NICU upholds an imperative of attachment independently of the infant's chances of survival, for parents, attachment is contingent on certain hesitations in relation to their infant. We...... argue that there are nuances in practices of relationmaking in need of more attention (i.e., the nexus of attachment and detachment). Refraining from touching, holding, and feeding their infants during critical periods, the parents enact detachment as integral to their practices of attachment....... Such “cuts” in parent–infant relations become steps on the way to securing the infant's survival and making kin(ship). We conclude that although infants may be articulated as “maybe‐lives” by staff, in the NICU as well as in Danish society, the ideal of attachment appears to leave little room for “maybe‐parents.”...

  11. The process of developing and changing of infant-teacher attachment : A study on an infant whose attachment to the first attachment figure is insecure

    OpenAIRE

    上田, 七生

    2003-01-01

    Toward infants whose attachment to their first attachment figures (mainly their mothers) is insecure, how can we intervene in them? To reveal it, an observation was carried out regularly once a week, over a period of 9 months. The subjects were an infant who has insecure attachment and comparative one who has secure attachment. And the attachment behaviors they exhibited toward nursery school teachers, strangers, and an observer were counted. The amount of the attachment behaviors of the infa...

  12. Many things come in small packages: Revision of the clawless geckos (Crenadactylus: Diplodactylidae) of Australia.

    Science.gov (United States)

    Doughty, Paul; Ellis, Ryan J; Oliver, Paul M

    2016-09-15

    We provide a taxonomic revision of the genus Crenadactylus, a group of very small clawless geckos from western and central Australia, with currently only one recognized species and four subspecies. Morphological comparisons were made on genotyped specimens from two recent genetic studies, then with an expanded sample to encompass all specimens to determine diagnostic characters in addition to morphological and geographic boundaries. Based on our findings, we           elevate the subspecies Crenadactylus ocellatus ocellatus from south-western Australia and C. o. horni from the Central Uplands to full species. Consultation of the types of Diplodactylus (= Crenadactylus) bilineatus indicate they are                 C. ocellatus based on a dorsal pattern with intermixing of dark and pale scales not shared with any other taxa; we therefore maintain synonymy of 'D.' bilineatus with 'D.' ocellatus. We describe three new Western Australian species formerly      allocated to C. o. horni: C. occidentalis sp. nov. from the western coast, C. tuberculatus sp. nov. from the Cape Range and C. pilbarensis sp. nov. from the Pilbara region. To stabilize the Kimberley taxa, we also raise C. ocellatus rostralis and C. ocellatus naso, both monophyletic taxa from the monsoonal tropics, to full species, while acknowledging further work is required on the C. naso species complex. All new species treated here possess distinctive morphological characters to diagnose them, including enlarged dorsal tubercles in C. tuberculatus sp. nov., a single enlarged supranasal in C. horni and a single enlarged postmental in C. pilbarensis sp. nov. Pattern was relatively conserved among taxa, with highly  contrasting dark and pale longitudinal lines, with the exception of the type species C. ocellatus that possesses intermixed dark and pale scales and ocelli. Crenadactylus species are separated by deep genetic divergences and are usually allopatrically distributed. This

  13. Effect of hormonal manipulation on sociosexual behavior in adult female leopard geckos (Eublepharis macularius), a species with temperature-dependent sex determination.

    Science.gov (United States)

    Flores, D L; Crews, D

    1995-12-01

    Aggressive and sexual behavior in the adult leopard gecko (Eublepharis macularius), a species with temperature-dependent sex determination (TSD), is influenced by the temperature experienced as an egg, as well as by prenatal and perinatal hormones. This study focused on the effects of hormonal manipulation of adult female leopard geckos from different incubation temperatures. Following ovariectomy, females from both all-female (26 degrees C) and male-biased (32.5 degrees C) incubation temperatures exhibited a significant decrease in high-posture (HP) aggression toward male and female stimulus animals. Testosterone treatment attenuated this decrease in HP aggression toward female but not toward male stimulus animals. Ovariectomy also resulted in a loss in attractiveness in both groups of females. Following treatment with testosterone, over 50% of the females were attacked by male stimulus animals, suggesting a change in the pheromonal cues normally secreted by females. Unmanipulated females never exhibit tail vibrations, a male-typical courtship behavior. However, following ovariectomy with testosterone treatment, half of the females from both incubation temperatures exhibited this behavior, indicating an activational effect of testosterone. An effect of incubation temperature on aggression was evident with females from the male-biased incubation temperature exhibiting a greater likelihood of aggression compared to females from the all-female incubation temperature. This effect continued to be detected after hormone manipulation. Ovariectomized females from the all-female incubation temperature were less aggressive even with testosterone treatment toward males, whereas females from the male-biased incubation temperature showed no significant decline in aggression following testosterone treatment, suggesting that individuals from different incubation temperatures may have different sensitivities to hormones.

  14. The relation of infant attachment to attachment and cognitive and behavioural outcomes in early childhood.

    Science.gov (United States)

    Ding, Yan-hua; Xu, Xiu; Wang, Zheng-yan; Li, Hui-rong; Wang, Wei-ping

    2014-09-01

    In China, research on the relation of mother-infant attachment to children's development is scarce. This study sought to investigate the relation of mother-infant attachment to attachment, cognitive and behavioural development in young children. This study used a longitudinal study design. The subjects included healthy infants (n=160) aged 12 to 18 months. Ainsworth's "Strange Situation Procedure" was used to evaluate mother-infant attachment types. The attachment Q-set (AQS) was used to evaluate the attachment between young children and their mothers. The Bayley scale of infant development-second edition (BSID-II) was used to evaluate cognitive developmental level in early childhood. Achenbach's child behaviour checklist (CBCL) for 2- to 3-year-olds was used to investigate behavioural problems. In total, 118 young children (73.8%) completed the follow-up; 89.7% of infants with secure attachment and 85.0% of infants with insecure attachment still demonstrated this type of attachment in early childhood (κ=0.738, pInfants with insecure attachment collectively exhibited a significantly lower mental development index (MDI) in early childhood than did infants with secure attachment, especially the resistant type. In addition, resistant infants were reported to have greater social withdrawal, sleep problems and aggressive behaviour in early childhood. There is a high consistency in attachment development from infancy to early childhood. Secure mother-infant attachment predicts a better cognitive and behavioural outcome; whereas insecure attachment, especially the resistant attachment, may lead to a lower cognitive level and greater behavioural problems in early childhood. Copyright © 2014 Elsevier Ltd. All rights reserved.

  15. Sentence-Level Attachment Prediction

    Science.gov (United States)

    Albakour, M.-Dyaa; Kruschwitz, Udo; Lucas, Simon

    Attachment prediction is the task of automatically identifying email messages that should contain an attachment. This can be useful to tackle the problem of sending out emails but forgetting to include the relevant attachment (something that happens all too often). A common Information Retrieval (IR) approach in analyzing documents such as emails is to treat the entire document as a bag of words. Here we propose a finer-grained analysis to address the problem. We aim at identifying individual sentences within an email that refer to an attachment. If we detect any such sentence, we predict that the email should have an attachment. Using part of the Enron corpus for evaluation we find that our finer-grained approach outperforms previously reported document-level attachment prediction in similar evaluation settings.

  16. R and D contract management systems in the USA (Attachment); Beikoku ni okeru R and D contract kanri system (tenpu shiryohen)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-02-01

    Presented herein is the attachment for 'R and D contract management systems in the USA'. The major contents include regulations governing the R and D contracts, procedures for the R and D contracts, financial procedures for the R and D contracts, procedures for the alternative R and D contracts, financial management of the R and D contracts, and activities for the management of the contract processes by electronic systems. (NEDO)

  17. Child's Attachment to Mother as the Basis of Mental Development Typology

    Directory of Open Access Journals (Sweden)

    Galina V. Burmenskaya

    2009-01-01

    Full Text Available The article shows the role of the attachment system (child-mother interactions in development of a wide spectrum of individual personality characteristics. Emotional attachment of the child to mother is considered as a complicated system of internal regulation and a basis of typology of mental development. Results of a series of empirical studies show the connection between the type of attachment, formed at the early stages of child development, and characteristics of his/her autonomy, consciousness (self-concept and self-esteem and empathy in preschool and middle childhood.

  18. An encounter between 4e cognition and attachment theory

    Science.gov (United States)

    Petters, Dean

    2016-10-01

    This paper explores a constructive revision of the conceptual underpinnings of Attachment Theory through an encounter with the diverse elements of 4e cognition. Attachment relationships involve the development of preference for one or a few carers and expectations about their availability and responsiveness as a haven of safety and a base from which to explore. In attachment theory, mental representations have been assigned a central organising role in explaining attachment phenomena. The 4e cognition approaches in cognitive science raise a number of questions about the development and interplay of attachment and cognition. These include: (1) the nature of what Bowlby called 'internal working models of attachment'; (2) the extent to which the infant-carer dyad functions as an extension of the infant's mind; and (3) whether Bowlby's attachment control system concept can be usefully re-framed in enactive terms where traditional cognitivist representations are: (3i) substituted for sensorimotor skill-focused mediating representations; (3ii) viewed as arising from autopoietic living organisms; and/or (3iii) mostly composed from the non-contentful mechanisms of basic minds? A theme that cross-cuts these research questions is how representations for capturing meaning, and structures for adaptive control, are both required to explain the full range of behaviour of interest to Attachment Theory researchers.

  19. ATTACHMENT AND TRANSFER

    OpenAIRE

    Pasare, Daniela

    2011-01-01

    Bowlby's concept of attachment and Freud's concept of transference are two of the most influential theories of how we construct mental representations of human relationships. The attachment’s theory offers one more strategy for the therapeutic approach. Factors that lead to a secure attachment between mother and child may also be applied to the relationship between patient and psychotherapist. Psychotherapy may help a patient create himself new attachment and relationship patterns. Creating a...

  20. Influence of packing density and surface roughness of vertically-aligned carbon nanotubes on adhesive properties of gecko-inspired mimetics.

    Science.gov (United States)

    Chen, Bingan; Zhong, Guofang; Oppenheimer, Pola Goldberg; Zhang, Can; Tornatzky, Hans; Esconjauregui, Santiago; Hofmann, Stephan; Robertson, John

    2015-02-18

    We have systematically studied the macroscopic adhesive properties of vertically aligned nanotube arrays with various packing density and roughness. Using a tensile setup in shear and normal adhesion, we find that there exists a maximum packing density for nanotube arrays to have adhesive properties. Too highly packed tubes do not offer intertube space for tube bending and side-wall contact to surfaces, thus exhibiting no adhesive properties. Likewise, we also show that the surface roughness of the arrays strongly influences the adhesion properties and the reusability of the tubes. Increasing the surface roughness of the array strengthens the adhesion in the normal direction, but weakens it in the shear direction. Altogether, these results allow progress toward mimicking the gecko's vertical mobility.

  1. Insights into Himalayan biogeography from geckos: a molecular phylogeny of Cyrtodactylus (Squamata: Gekkonidae).

    Science.gov (United States)

    Agarwal, Ishan; Bauer, Aaron M; Jackman, Todd R; Karanth, K Praveen

    2014-11-01

    The India-Asia collision profoundly influenced the climate, topography and biodiversity of Asia, causing the formation of the biodiverse Himalayas. The species-rich gekkonid genus Cyrtodactylus is an ideal clade for exploring the biological impacts of the India-Asia collision, as previous phylogenetic hypotheses suggest basal divergences occurred within the Himalayas and Indo-Burma during the Eocene. To this end, we sampled for Cyrtodactylus across Indian areas of the Himalayas and Indo-Burma Hotspots and used three genes to reconstruct relationships and estimate divergence times. Basal divergences in Cyrtodactylus, Hemidactylus and the Palaearctic naked-toed geckos were simultaneous with or just preceded the start of the India-Asia collision. Diversification within Cyrtodactylus tracks the India-Asia collision and subsequent geological events. A number of geographically concordant clades are resolved within Indo-Burmese Cyrtodactylus. Our study reveals 17 divergent lineages that may represent undescribed species, underscoring the previously undocumented diversity of the region. The importance of rocky habitats for Cyrtodactylus indicates the Indo-Gangetic flood plains and the Garo-Rajmahal Gap are likely to have been important historical barriers for this group. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. VEGF, FGF-2 and TGFβ expression in the normal and regenerating epidermis of geckos: implications for epidermal homeostasis and wound healing in reptiles.

    Science.gov (United States)

    Subramaniam, Noeline; Petrik, James J; Vickaryous, Matthew K

    2018-05-01

    The skin is a bilayered organ that serves as a key barrier between an organism and its environment. In addition to protecting against microbial invasion, physical trauma and environmental damage, skin participates in maintaining homeostasis. Skin is also capable of spontaneous self-repair following injury. These functions are mediated by numerous pleiotrophic growth factors, including members of the vascular endothelial growth factor (VEGF), fibroblast growth factor (FGF), and transforming growth factor β (TGFβ) families. Although growth factor expression has been well documented in mammals, particularly during wound healing, for groups such as reptiles less is known. Here, we investigate the spatio-temporal pattern of expression of multiple growth factors in normal skin and following a full-thickness cutaneous injury in the representative lizard Eublepharis macularius, the leopard gecko. Unlike mammals, leopard geckos can heal cutaneous wounds without scarring. We demonstrate that before, during and after injury, keratinocytes of the epidermis express a diverse panel of growth factor ligands and receptors, including: VEGF, VEGFR1, VEGFR2, and phosphorylated VEGFR2; FGF-2 and FGFR1; and phosphorylated SMAD2, TGFβ1, and activin βA. Unexpectedly, only the tyrosine kinase receptors VEGFR1 and FGFR1 were dynamically expressed, and only during the earliest phases of re-epithelization; otherwise all the proteins of interest were constitutively present. We propose that the ubiquitous pattern of growth factor expression by keratinocytes is associated with various roles during tissue homeostasis, including protection against ultraviolet photodamage and coordinated body-wide skin shedding. © 2018 Anatomical Society.

  3. Measuring Patients’ Attachment Avoidance in Psychotherapy: Development of the Attachment Avoidance in Therapy Scale (AATS

    Directory of Open Access Journals (Sweden)

    András Láng

    2012-11-01

    Full Text Available A new scale measuring patient-therapist attachment avoidance was developed. Attachment Avoidance in Therapy Scale is a new measure based on the Bartholomew model of adult attachment (Bartholomew & Horowitz, 1991 and the Experience in Close Relationships Scale (Brennan, Clark, & Shaver, 1998 to measure patients’ attachment avoidance towards therapists. With 112 patient-therapist dyads participating in the study, validation of a preliminary scale – measuring both attachment anxiety and attachment avoidance in therapy – took place using therapists’ evaluations of patients’ relational behavior and patients’ self-reports about their attitude toward psychotherapy. Analysis of the data revealed six underlying scales. Results showed all six scales to be reliable. Validation of scales measuring attachment anxiety failed. The importance of Attachment Avoidance in Therapy Scale and its subscales is discussed.

  4. The Form and Function of Attachment Behavior in the Daily Lives of Young Adults

    Science.gov (United States)

    Campa, Mary I.; Hazan, Cindy; Wolfe, Jared E.

    2009-01-01

    Central to attachment theory is the postulation of an inborn system to regulate attachment behavior. This system has been well studied in infancy and childhood, but much less is known about its functioning at later ages. The goal of this study was to explore the form and function of attachment behavior in the daily lives of young adults. Twenty…

  5. Special Attachments. Module 19.

    Science.gov (United States)

    South Carolina State Dept. of Education, Columbia. Office of Vocational Education.

    This module on special attachments, one in a series dealing with industrial sewing machines, their attachments, and operation, covers four topics: gauges; cording attachment; zipper foot; and hemming, shirring, and binding. For each topic these components are provided: an introduction, directions, an objective, learning activities, student…

  6. [Infants' attachment security in a vulnerable French sample].

    Science.gov (United States)

    Tereno, S; Guedeney, N; Dugravier, R; Greacen, T; Saïas, T; Tubach, F; Ulgen, S; Matos, I; Guédeney, A

    2017-04-01

    Attachment is a long lasting emotional link established between infants and their caregivers. The quality of early relationships allows infants to safely explore their environment and contribute to the establishment of a broad range of social skills. Several intervention programs targeting infant attachment have been implemented in different contexts, showing diverse degrees of efficacy. The present paper describes, for the first time, children's attachment quality distributions in a French multi-risk population, with a preventive intervention, usual or reinforced. In the CAPEDP study (Parenting and Attachment in Early Childhood: reducing mental health disorder risks and promoting resilience), a sub-sample of 117 women was recruited to assess the effects of this home-visiting program on children's attachment security. With that intent, the Strange Situation Paradigm was used when infants were between 12 and 16 months of age. In the intervention group, 63% (n=41) of the infants were coded as secure, while 15% (n=10) of them were coded as insecure-avoidant and 22% (n=14) as insecure-ambivalent/resistant. 56% (n=29) of control group infants (usual care) were coded as secure, while 27% (n=14) were coded as insecure-avoidant and 17% (n=9) as insecure-ambivalent/resistant. Even if the percentage of children with a secure attachment in the reinforced intervention group was higher than that of the control group, this difference did not reach the threshold of significance [Chi 2 (2)=2.40, P=0.30]. Intervention group distributions were closer to normative samples, and these distributions show the clinical impact of our program. In general, preventive interventions focused on attachment quality have moderate effects but, in our case, several factors might have contributed to lower the statistical impact of the program. Firstly, the control group cannot be considered has having received zero intervention for two reasons: (a) the French usual perinatal health system (Maternal

  7. From security to attachment : Mary Ainsworth's contribution to attachment theory

    NARCIS (Netherlands)

    Rosmalen, Lenette (Lenny) van

    2015-01-01

    Even though John Bowlby (1907-1990) is generally regarded as the founder of attachment theory, Mary Ainsworth’s (1913-1999) contribution is considerable and goes beyond the design of the Strange Situation Procedure and the introduction of maternal sensitivity as decisive for a secure attachment

  8. Dry adhesives from carbon nanofibers grown in an open ethanol flame

    Directory of Open Access Journals (Sweden)

    Christian Lutz

    2017-12-01

    Full Text Available Based on magnetic-field-assisted growth of carbon nanofibers in an open ethanol flame we fabricated arrays of carbon nanofibers with different degrees of orientation. Inspired by the dry adhesive system of geckos we investigated the adhesive properties of such carbon nanofiber arrays with ordered and random orientation. AFM-based force spectroscopy revealed that adhesion force and energy rise linear with preload force. Carbon nanofibers oriented by a magnetic field show a 68% higher adhesion (0.66 N/cm2 than the randomly oriented fibers. Endurance tests revealed that the carbon nanofiber arrays withstand 50.000 attachment/detachment cycles without observable wear.

  9. The role of attachment in recovery after a school-shooting trauma

    Directory of Open Access Journals (Sweden)

    Tuija Turunen

    2014-07-01

    Full Text Available Background: Survivors of life-endangering trauma use varying resources that help them to recover. Attachment system activates in the times of distress, and is expected to associate with stress responses, arousal regulation, and mental health. Objective: We examined the associations of attachment style with posttraumatic stress disorders (PTSD symptoms and dissociative symptoms, and posttraumatic growth (PTG among students exposed to a school shooting in Finland in a three-wave follow-up setting. Method: Participants were students (M age=24.9 years; 95% female who were followed 4 (T1, N=236, 16 (T2, N=180, and 28 months (T3, N=137 after the shooting. The assessments included the Attachment Style Questionnaire, the Impact of Event Scale, part of the Adolescent Dissociative Experiences Scale and the Posttraumatic Growth Inventory. Results: Securely attached survivors had lower levels of posttraumatic stress and dissociative symptoms than preoccupied at T1 and T2 as hypothesized. At T3 survivors with avoidant attachment style had higher levels of intrusive and hyperarousal symptoms than those with secure style. Concerning PTG, survivors with avoidant attachment style scored lower in PTG at T3 than survivors with both secure and preoccupied style. Conclusion: Secure attachment style was beneficial in trauma recovery. A challenge to the health care systems is to acknowledge that survivors with preoccupied and avoidant attachment styles react uniquely to trauma, and thus need help in different doses, modalities, and timings.

  10. Attachment, assessment, and psychological intervention: a case study of anorexia.

    Science.gov (United States)

    Lis, Adriana; Mazzeschi, Claudia; Di Riso, Daniela; Salcuni, Silvia

    2011-01-01

    Attachment patterns and personality dimensions have always been considered important to the development and adaptation of the individual. The first aim of this article was to address some basic questions about the place of attachment in a multimethod assessment when compiling a complete picture of the patient's personality functioning. The second aim was to present the Adult Attachment Projective Picture System (AAP; George & West, 2001) as a valid and productive assessment measure. Based on a single case study of an anorexic young woman, the article demonstrates how the AAP is integrated with the Rorschach Comprehensive System (Exner, 1991, 1993) and other assessment tools in both the assessment and in developing a treatment plan.

  11. The Politics of Attachment: Lines of Flight with Bowlby, Deleuze and Guattari.

    Science.gov (United States)

    Duschinsky, Robbie; Greco, Monica; Solomon, Judith

    2015-12-01

    Research on attachment is widely regarded in sociology and feminist scholarship as politically conservative - oriented by a concern to police families, pathologize mothers and emphasize psychological at the expense of socio-economic factors. These critiques have presented attachment theory as constructing biological imperatives to naturalize contingent, social demands. We propose that a more effective critique of the politically conservative uses of attachment theory is offered by engaging with the 'attachment system' at the level of ontology. In developing this argument we draw on Deleuze and Guattari, making use of the common language of ethology which links their ideas to that of attachment theory. The attachment system can and has been reified into an image of the infant returning to their caregiver as an image of familial sufficiency. This has offered ammunition for discourses and institutions which isolate women from health, social and political resources. Yet Deleuze and Guattari can help attachment theory and research to be recognized as a powerful ally for progressive politics, for reflection on the movement of human individuation, and for arguing for the meaningful resourcing of those who care for someone else.

  12. Lightning attachment process to common buildings

    Science.gov (United States)

    Saba, M. M. F.; Paiva, A. R.; Schumann, C.; Ferro, M. A. S.; Naccarato, K. P.; Silva, J. C. O.; Siqueira, F. V. C.; Custódio, D. M.

    2017-05-01

    The physical mechanism of lightning attachment to grounded structures is one of the most important issues in lightning physics research, and it is the basis for the design of the lightning protection systems. Most of what is known about the attachment process comes from leader propagation models that are mostly based on laboratory observations of long electrical discharges or from observations of lightning attachment to tall structures. In this paper we use high-speed videos to analyze the attachment process of downward lightning flashes to an ordinary residential building. For the first time, we present characteristics of the attachment process to common structures that are present in almost every city (in this case, two buildings under 60 m in São Paulo City, Brazil). Parameters like striking distance and connecting leaders speed, largely used in lightning attachment models and in lightning protection standards, are revealed in this work.Plain Language SummarySince the time of Benjamin Franklin, no one has ever recorded high-speed video images of a lightning connection to a common building. It is very difficult to do it. Cameras need to be very close to the structure chosen to be observed, and long observation time is required to register one lightning strike to that particular structure. Models and theories used to determine the zone of protection of a lightning rod have been developed, but they all suffer from the lack of field data. The submitted manuscript provides results from high-speed video observations of lightning attachment to low buildings that are commonly found in almost every populated area around the world. The proximity of the camera and the high frame rate allowed us to see interesting details that will improve the understanding of the attachment process and, consequently, the models and theories used by lightning protection standards. This paper also presents spectacular images and videos of lightning flashes connecting lightning rods that

  13. Quantifying Attachment and Antibiotic Resistance of from Conventional and Organic Swine Manure.

    Science.gov (United States)

    Zwonitzer, Martha R; Soupir, Michelle L; Jarboe, Laura R; Smith, Douglas R

    2016-03-01

    Broad-spectrum antibiotics are often administered to swine, contributing to the occurrence of antibiotic-resistant bacteria in their manure. During land application, the bacteria in swine manure preferentially attach to particles in the soil, affecting their transport in overland flow. However, a quantitative understanding of these attachment mechanisms is lacking, and their relationship to antibiotic resistance is unknown. The objective of this study is to examine the relationships between antibiotic resistance and attachment to very fine silica sand in collected from swine manure. A total of 556 isolates were collected from six farms, two organic and four conventional (antibiotics fed prophylactically). Antibiotic resistance was quantified using 13 antibiotics at three minimum inhibitory concentrations: resistant, intermediate, and susceptible. Of the 556 isolates used in the antibiotic resistance assays, 491 were subjected to an attachment assay. Results show that isolates from conventional systems were significantly more resistant to amoxicillin, ampicillin, chlortetracycline, erythromycin, kanamycin, neomycin, streptomycin, tetracycline, and tylosin ( < 0.001). Results also indicate that isolated from conventional systems attached to very fine silica sand at significantly higher levels than those from organic systems ( < 0.001). Statistical analysis showed that a significant relationship did not exist between antibiotic resistance levels and attachment in from conventional systems but did for organic systems ( < 0.001). Better quantification of these relationships is critical to understanding the behavior of in the environment and preventing exposure of human populations to antibiotic-resistant bacteria. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

  14. Attachment of iron corrosion products on steam generator tube and feed-water pump in PWRs secondary system

    International Nuclear Information System (INIS)

    Shoda, Y.; Ishihara, N.; Miyata, H.; Ohira, T.; Watanabe, Y.; Nonaka, Y.

    2010-01-01

    Operating experience of the secondary systems in PWRs indicates that scale attachment distinctly have an effect on the performance of water-steam cycle. Attached scale on outer surface of steam generator (SG) tube could induce many problems such as decrease heat efficiency of plant, corrosion of tube by intergranular attack (IGA), and choke of flow channel. Scale attached on rotor blade of feed water pump increases the driving steam consumption to keep the constant flow rate, and results in the thermal efficiency decrease of the plant. In this study, two types of test about scale deposition on equipment were executed in the conditions simulating the secondary system of PWR. One is SG model test, which simulated the circulating boiler composed of single SG tube and blow down line. The deposition rate under AVT condition was equivalent to plants revealed with extended period. High-AVT test provided useful reference, because the deposition rate of power plant is too small to measure in a short period after the beginning of High-AVT operation in Japan. The other is feed water pump model test. The mock-up pump is composed of a rotating stainless steel disk. As a result, it is confirmed that the deposition rate depends mostly on iron concentration in water and the exfoliation rate depends mainly on pH. Applying this information, the scale deposition-growth behavior on the equipment is quantitatively expressed by the model combined of scale deposition behavior and exfoliation behavior couples with the former. These results bring effective estimation for suppressing deposition-growth by the selection of water chemistry management and/or equipment improvement in the PWR secondary system. (author)

  15. Material Evaluation of an Elastomer, Epoxy and Lightweight Concrete Rail Attachment System for Direct Fixation Light Rail Applications

    Science.gov (United States)

    Swarner, Benjamin R.

    Sound Transit plans to extend its current light rail system, which runs along the I-5 corridor in Seattle, Washington, across the I-90 Homer Hadley floating bridge as part of a project to connect the major city centers in the region. But, no light rail has ever crossed a floating bridge due to several unique engineering challenges. One of these challenges is attaching the rails to the existing bridge deck without drilling into the bridge pontoons. This research program was developed to test and analyze a direct fixation method that uses lightweight concrete plinths and an elastomer-epoxy system to attach the rails to the bridge deck. The elastomer used was a two-part, pourable elastomer with cork particles intermixed to alter the mechanical properties of the material. A lightweight concrete mixture was analyzed for use in the plinths, and system tests investigated the system response under tensile, compressive and shear loading. The shear response of the system was examined further under varying loading conditions including different surface preparations, elastomer thicknesses, strain-rates and after freeze-thaw conditioning. Experimental data was examined for trends based on these parameters to best characterize the system, and the elastomer was evaluated in the context of modern elastomer research.

  16. Structural Interfaces and Attachments in Biology

    CERN Document Server

    Birman, Victor; Genin, Guy

    2013-01-01

    Attachment of dissimilar materials in engineering and surgical practice is a perennial challenge. Bimaterial attachment sites are common locations for injury, repeated injury, and mechanical failure. Nature presents several highly effective solutions to the challenge of bimaterial attachment that differ from those found in engineering practice. Structural Interfaces and Attachments in Biology describes the attachment of dissimilar materials from multiple perspectives. The text will simultaneously elucidate natural bimaterial attachments and outline engineering principles underlying successful attachments to the communities of tissue engineers and surgeons. Included an in-depth analysis of the biology of attachments in the body and mechanisms by which robust attachments are formed, a review of current concepts of attaching dissimilar materials in surgical practice and a discussion of bioengineering approaches that are currently being developed. This book also: Provides the first comprehensive treatment of phys...

  17. Attachment and psychosis

    NARCIS (Netherlands)

    Korver, N.

    2014-01-01

    The main goal of this thesis was to further our understanding of current psychosocial models by introducing attachment as a relevant developmental framework. Firstly, attachment theory provides a psychosocial model for a developmental pathway to psychosis. Secondly, after expression of psychotic

  18. Effect of Attachment-Based Therapy on Behavioral Disorders in Girls with Attachment Problems

    Directory of Open Access Journals (Sweden)

    Marzieh Jahanbakhsh

    2014-09-01

    Full Text Available Background: Multidimensional and complex nature of children`s behavioral disorders requires assessment and usage of modern treatments. The present study investigated the effects of attachment-based therapy on behavioral disorders (depression, over anxiety and oppositional defiant in girl students of primary school who had attachment problems. Materials and Methods: This study is an empirical plan with pretest-posttest and control group. The target samples were 34 individuals of 388 second and fourth grade students of primary school that had highest scores on attachment problems and behavioral disorders (depression, over anxiety and oppositional defiant. Evaluation implemented using Randolph attachment disorder questionnaire (RADQ and Ontario mental health test. Mothers were presented in 10 group sessions of attachment-based intervention and its effects investigated in their girl`s behavioral disorders (depression, over anxiety and oppositional defiant. Results: Reduction rate of behavioral disorders general scores (depression, over anxiety and oppositional defiant of experimental group compared with control group showed significant decreases in posttest and three months follow up. Conclusion: The attachment based therapy offered for mothers of the girls with attachment problems was effective to reduction of behavioral disorders (depression, over anxiety and oppositional defiant symptoms in their children and the mother`s continues attention to interventional methods showed more improvement in follow up evaluation.

  19. Associations among Adult Attachment Presentations, Maternal Sensitivity, and Infant-Mother Attachment in a Sample of Adolescent Mothers.

    Science.gov (United States)

    Ward, Mary J.; Carlson, Elizabeth A.

    1995-01-01

    Associations among adolescent attachment organization, maternal sensitivity, and infant attachment organization were examined prospectively in 72 teenaged mother-infant dyads. Pregnant teenagers' attachment organizations predicted both sensitivity and infant-mother attachments. Associations between maternal sensitivity and infant attachment were…

  20. Attachment, Neurobiology, and Mentalizing along the Psychosis Continuum.

    Science.gov (United States)

    Debbané, Martin; Salaminios, George; Luyten, Patrick; Badoud, Deborah; Armando, Marco; Solida Tozzi, Alessandra; Fonagy, Peter; Brent, Benjamin K

    2016-01-01

    In this review article, we outline the evidence linking attachment adversity to psychosis, from the premorbid stages of the disorder to its clinical forms. To better understand the neurobiological mechanisms through which insecure attachment may contribute to psychosis, we identify at least five neurobiological pathways linking attachment to risk for developing psychosis. Besides its well documented influence on the hypothalamic-pituary-adrenal (HPA) axis, insecure attachment may also contribute to neurodevelopmental risk through the dopaminergic and oxytonergic systems, as well as bear influence on neuroinflammation and oxidative stress responses. We further consider the neuroscientific and behavioral studies that underpin mentalization as a suite of processes potentially moderating the risk to transition to psychotic disorders. In particular, mentalization may help the individual compensate for endophenotypical impairments in the integration of sensory and metacognitive information. We propose a model where embodied mentalization would lie at the core of a protective, resilience response mitigating the adverse and potentially pathological influence of the neurodevelopmental cascade of risk for psychosis.

  1. Stamina in adults: is attachment style a factor?

    Science.gov (United States)

    Pellegrini, R J; Hicks, R A; Roundtree, T; Inman, G M

    2000-10-01

    The study was designed to extend inquiry on adult attachment style to include the variable of personal stamina. The data were derived from an anonymous survey administered to 163 college students (82 women and 81 men) in introductory psychology classes. Attachment style was measured by the Close Relationship Questionnaire, based on a four-category scheme suggested by Bartholomew. Stamina was evaluated with a self-report scale developed by R. A. Hicks. The pattern of statistically significant differences (p stamina scores than did those who self-endorsed the fearful or preoccupied alternatives in that categorical measure. No other pairwise comparisons of stamina scores were statistically significant. The results provide preliminary support for the hypothesis that secure attachment is more facilitative of personal stamina than are insecure styles. Methodological limits on inferences and corresponding alternative interpretations, the potential effectiveness of defensive suppression of the attachment system in dismissing-avoidant adults, and directions for research are discussed.

  2. Attachment, Neurobiology, and Mentalizing along the Psychosis Continuum

    Science.gov (United States)

    Debbané, Martin; Salaminios, George; Luyten, Patrick; Badoud, Deborah; Armando, Marco; Solida Tozzi, Alessandra; Fonagy, Peter; Brent, Benjamin K.

    2016-01-01

    In this review article, we outline the evidence linking attachment adversity to psychosis, from the premorbid stages of the disorder to its clinical forms. To better understand the neurobiological mechanisms through which insecure attachment may contribute to psychosis, we identify at least five neurobiological pathways linking attachment to risk for developing psychosis. Besides its well documented influence on the hypothalamic-pituary-adrenal (HPA) axis, insecure attachment may also contribute to neurodevelopmental risk through the dopaminergic and oxytonergic systems, as well as bear influence on neuroinflammation and oxidative stress responses. We further consider the neuroscientific and behavioral studies that underpin mentalization as a suite of processes potentially moderating the risk to transition to psychotic disorders. In particular, mentalization may help the individual compensate for endophenotypical impairments in the integration of sensory and metacognitive information. We propose a model where embodied mentalization would lie at the core of a protective, resilience response mitigating the adverse and potentially pathological influence of the neurodevelopmental cascade of risk for psychosis. PMID:27597820

  3. NAFFS: network attached flash file system for cloud storage on portable consumer electronics

    Science.gov (United States)

    Han, Lin; Huang, Hao; Xie, Changsheng

    Cloud storage technology has become a research hotspot in recent years, while the existing cloud storage services are mainly designed for data storage needs with stable high speed Internet connection. Mobile Internet connections are often unstable and the speed is relatively low. These native features of mobile Internet limit the use of cloud storage in portable consumer electronics. The Network Attached Flash File System (NAFFS) presented the idea of taking the portable device built-in NAND flash memory as the front-end cache of virtualized cloud storage device. Modern portable devices with Internet connection have built-in more than 1GB NAND Flash, which is quite enough for daily data storage. The data transfer rate of NAND flash device is much higher than mobile Internet connections[1], and its non-volatile feature makes it very suitable as the cache device of Internet cloud storage on portable device, which often have unstable power supply and intermittent Internet connection. In the present work, NAFFS is evaluated with several benchmarks, and its performance is compared with traditional network attached file systems, such as NFS. Our evaluation results indicate that the NAFFS achieves an average accessing speed of 3.38MB/s, which is about 3 times faster than directly accessing cloud storage by mobile Internet connection, and offers a more stable interface than that of directly using cloud storage API. Unstable Internet connection and sudden power off condition are tolerable, and no data in cache will be lost in such situation.

  4. Cladding Attachment Over Thick Exterior Insulating Sheathing

    Energy Technology Data Exchange (ETDEWEB)

    Baker, P. [Building Science Corporation, Somerville, MA (United States); Eng, P. [Building Science Corporation, Somerville, MA (United States); Lepage, R. [Building Science Corporation, Somerville, MA (United States)

    2014-01-01

    The addition of insulation to the exterior of buildings is an effective means of increasing the thermal resistance of both wood framed walls as well as mass masonry wall assemblies. For thick layers of exterior insulation (levels greater than 1.5 inches), the use of wood furring strips attached through the insulation back to the structure has been used by many contractors and designers as a means to provide a convenient cladding attachment location (Straube and Smegal 2009, Pettit 2009, Joyce 2009, Ueno 2010). The research presented in this report is intended to help develop a better understanding of the system mechanics involved and the potential for environmental exposure induced movement between the furring strip and the framing. BSC sought to address the following research questions: 1. What are the relative roles of the mechanisms and the magnitudes of the force that influence the vertical displacement resistance of the system? 2. Can the capacity at a specified deflection be reliably calculated using mechanics based equations? 3. What are the impacts of environmental exposure on the vertical displacement of furring strips attached directly through insulation back to a wood structure?

  5. Attachment to the Romantic Partner and Sibling: Attachment Hierarchies of Twins and Non-Twin Siblings

    Directory of Open Access Journals (Sweden)

    Sascha Schwarz

    2015-12-01

    Full Text Available Previous studies have shown that romantic partners and siblings are important attachment figures. This study compares the attachment to the romantic partner with the attachment to the sibling as a function of the participant’s sibling type among monozygotic (MZ twins, dizygotic (DZ twins, and non-twin (NT siblings. The results show that MZ twins prefer their sibling to their romantic partner whereas DZ twins are equally attached to their sibling and romantic partner. In contrast, NT siblings are more attached to their romantic partner compared to their sibling. These results indicate that genetic relatedness has profound impact on a person’s attachment hierarchy and the relative rank of the romantic partner and the sibling.

  6. Childhood Attachment to Pets: Associations between Pet Attachment, Attitudes to Animals, Compassion, and Humane Behaviour

    Directory of Open Access Journals (Sweden)

    Roxanne D. Hawkins

    2017-05-01

    Full Text Available Attachment to pets has an important role in children’s social, emotional, and cognitive development, mental health, well-being, and quality of life. This study examined associations between childhood attachment to pets and caring and friendship behaviour, compassion, and attitudes towards animals. This study also examined socio-demographic differences, particularly pet ownership and pet type. A self-report survey of over one thousand 7 to 12 year-olds in Scotland, UK, revealed that the majority of children are strongly attached to their pets, but attachment scores differ depending on pet type and child gender. Analysis revealed that attachment to pets is facilitated by compassion and caring and pet-directed friendship behaviours and that attachment to pets significantly predicts positive attitudes towards animals. The findings have implications for the promotion of prosocial and humane behaviour. Encouraging children to participate in pet care behaviour may promote attachment between children and their pet, which in turn may have a range of positive outcomes for both children (such as reduced aggression, better well-being, and quality of life and pets (such as humane treatment. This study enhances our understanding of childhood pet attachment and has implications for humane education and promoting secure emotional attachments in childhood.

  7. Gonococcal attachment to eukaryotic cells

    International Nuclear Information System (INIS)

    James, J.F.; Lammel, C.J.; Draper, D.L.; Brown, D.A.; Sweet, R.L.; Brooks, G.F.

    1983-01-01

    The attachment of Neisseria gonorrhoeae to eukaryotic cells grown in tissue culture was analyzed by use of light and electron microscopy and by labeling of the bacteria with [ 3 H]- and [ 14 C]adenine. Isogenic piliated and nonpiliated N. gonorrhoeae from opaque and transparent colonies were studied. The results of light microscopy studies showed that the gonococci attached to cells of human origin, including Flow 2000, HeLa 229, and HEp 2. Studies using radiolabeled gonococci gave comparable results. Piliated N. gonorrhoeae usually attached in larger numbers than nonpiliated organisms, and those from opaque colonies attached more often than isogenic variants from transparent colonies. Day-to-day variation in rate of attachment was observed. Scanning electron microscopy studies showed the gonococcal attachment to be specific for microvilli of the host cells. It is concluded that more N. gonorrhoeae from opaque colonies, as compared with isogenic variants from transparent colonies, attach to eukaryotic cells grown in tissue culture

  8. Concordance of attachment representations in preschool siblings assessed by the attachment story completion task

    OpenAIRE

    Werner, Helene; Zahn, Salome; Titze, Karl; Walitza, Susanne; Zulauf Logoz, Marina

    2015-01-01

    Several studies have indicated only a modest concordance of attachment security in siblings in infancy. Until now, very little was known about the concordance of siblings’ attachment security beyond infancy, as assessed by the attachment story completion task. This cross-sectional study aims to examine the concordance of attachment representations of 38 first-born (4–7 years) and 38 second-born (3–5 years) siblings living in middle-class two-parent families. Personality factors and the level ...

  9. [The interpretation of attachment in the Szondi test and in the questionnaire processes of attachment theory].

    Science.gov (United States)

    Török I, András; Vincze, Gábor

    2011-01-01

    [corrected] The Szondi-test is widely applied in clinical diagnostics in Hungary too, and the evidence resulting from the theory is that we can get information about attachment during its interpreting. Its validity is proven by empirical research and clinical experiences. By analyzing the modern attachment theory more thoroughly, it becomes clear in what ways the Szondi-test constellations regarding attachment are different from the classificationbased on questionnaires, allowing the discrete measurement of the attachment style. With the Szondi-test the classification to attachment style is more insecure, but if it is completed with exploration, it is more informative in vector C (vector of relation, attachment information), while short questionnaires make the classification to attachment style possible. In our empirical analysis we represent the integration of the above mentioned clinical and theoretical experiences. In the present analysis we compare the vector C and S constellation of the two-profile Szondi-test of 80 persons with the dimensions of ECR-R questionnaire and with Collins and Read's questionnaire classification regarding attachment style. The statistical results refer to the fact that there is a legitimacy to compare questionnaire processes allowing the discrete classification of attachment and the Szondi-test's information content regarding attachment. With applying the methods together, we get a unique, complementary section of the information relating to attachment. Comparing the two methods (projective and questionnaire) establishes the need of theoretical integration as well. We also make an attempt to explain Fraley's evolutionary non-adaptivity of avoidant attachment, in the case of whose presence adaptivity of early attachment, counterbalancing the exploration and security need, and providing closeness--farness loses its balance.

  10. A new biogeographically disjunct giant gecko (Gehyra: Gekkonidae: Reptilia) from the East Melanesian Islands

    Science.gov (United States)

    Oliver, Paul M.; Clegg, Jonathan R.; Fisher, Robert N.; Richards, Stephen J.; Taylor, Peter N.; Jocque, Merlijn M. T.

    2016-01-01

    The East Melanesian Islands have been a focal area for research into island biogeography and community ecology. However, previously undescribed and biogeographically significant new species endemic to this region continue to be discovered. Here we describe a phylogenetically distinct (~20% divergence at the mitochondrial ND2 gene) and biogeographically disjunct new species of gecko in the genus Gehyra, from the Admiralty and St Matthias Islands. Gehyra rohan sp. nov. can be distinguished from all congeners by the combination of its very large size, ring of bright orange scales around the eye, moderate degree of lateral folding on the limbs and body, and aspects of head, body and tail scalation. Molecular data indicate mid to late Miocene divergence of the new species from nearest relatives occurring nearly 2000 kilometres away in Vanuatu and Fiji. Large Gehyra have not been recorded on the intervening large islands of the Bismark Archipelago (New Britain and New Ireland) and the Solomon Islands, suggesting this dispersal pre-dated the current configuration of these islands, extinction in intervening regions, or potentially elements of both. Conversely, low genetic divergence between disjunct samples on Manus and Mussau implies recent overseas dispersal via either natural or anthropogenic means.

  11. Attachment theory: progress and future directions.

    Science.gov (United States)

    Fearon, R M Pasco; Roisman, Glenn I

    2017-06-01

    Attachment is a key subfield in the area of parenting and parent-child relationships research. In this brief overview, we summarise what we consider to be the state-of-the-art of attachment research, focusing primarily on the nature and significance of attachment in infancy and early childhood. We review 4 major topics that are central issues in the scientific literature on attachment: (1) the role of the environment in the development of attachment, (2) the intergenerational transmission of patterns of attachment, (3) the stability of attachment patterns through early adulthood, and (4) the role of attachment in adjustment and maladjustment. We conclude by highlighting several critical unresolved issues and priorities for future research. Copyright © 2017. Published by Elsevier Ltd.

  12. Visceral larva migrans associated with earthworm and gecko ingestion: a case report

    Directory of Open Access Journals (Sweden)

    Yu Tao

    2012-07-01

    Full Text Available Abstract Introduction Visceral larva migrans is a syndrome caused by an infection with larval helminths, which may result in partial or general pathological changes in host tissues. Due to the difficulty in finding the causative parasites, the diagnosis of visceral larva migrans is generally based on compatible clinical signs, epidemic history, marked eosinophilia and pathological examination, especially positive serological test results and the disappearance of symptoms after specific treatment. Case presentation We report here the case of a 21-year-old Chinese man who, having ingested living earthworms and geckos at a witch’s suggestion, presented with fatigue and wordlessness lasting for one year along with elevated transaminase levels for one month. Clinical examination showed eosinophilia, elevated transaminase levels, nodular lesions in his liver and typical pathological characteristics of hepatic visceral larva migrans. After four courses of anthelmintic therapy, our patient presented with sustaining improvement of clinical manifestations and normalization of laboratory data. Conclusions Because of the difficulty in making a definite diagnosis, anthelmintic therapy should be performed in patients with a suspected diagnosis of visceral larva migrans based on their epidemic history and presence of typical manifestations, especially when the serological test results are negative. Furthermore, patients with severe parasite infection may require multiple anthelmintic therapies in order to eliminate the parasites.

  13. Pin and roller attachment system for ceramic blades

    Science.gov (United States)

    Shaffer, J.E.

    1995-07-25

    In a turbine, a plurality of blades are attached to a turbine wheel by way of a plurality of joints which form a rolling contact between the blades and the turbine wheel. Each joint includes a pin and a pair of rollers to provide rolling contact between the pin and an adjacent pair of blades. Because of this rolling contact, high stress scuffing between the blades and the turbine wheel reduced, thereby inhibiting catastrophic failure of the blade joints. 3 figs.

  14. Attachment icebergs: Maternal and child health nurses' evaluation of infant-caregiver attachment.

    Science.gov (United States)

    Bryant, Edith; Ridgway, Lael; Lucas, Sandra

    2016-05-01

    Secure attachment of infants to their caregiver is important when promoting the emotional wellbeing and mental health of infants. Maternal and child health (MCH) nurses are well positioned to observe the quality of interactions between infants and caregivers and to assess and intervene. However, as yet there are no approved methods to assess the emotional and mental health of infants in community settings. A qualitative descriptive study of 12 MCH nurses in Victoria, Australia, using semi-structured interviews, was thematically analysed. The data revealed that nurses used many skills to identify and manage attachment difficulties. Key among these were observations of interactions, collaboration with caregivers and reflective practice. Assessments and interventions are also influenced by nurses' emotions, attitudes and workplace factors. An unexpected finding was that attachment markers can be likened to an 'iceberg': warning indicators at the tip can be easily observed by the nurse, while the less obvious underlying factors need to be explored in order to support attachment and improve infant mental health outcomes. Education for nurses should include concepts of attachment and link behaviours with emotional wellbeing.

  15. In vitro retention force measurement for three different attachment systems for implant-retained overdenture

    Directory of Open Access Journals (Sweden)

    Kareem Mohammed Reda

    2016-01-01

    Conclusion: Regardless of the initial retention level of overdenture attachment, gradual loss of retention values is inevitable. However, the rate of retention loss in overdenture attachments is higher in types which comprised plastic parts within their components, rather than those totally made up of noble metals.

  16. Loveridge’s Angolan geckos, Afroedura karroica bogerti and Pachydactylus scutatus angolensis (Sauria, Gekkonidae: new distribution records, comments on type localities and taxonomic status

    Directory of Open Access Journals (Sweden)

    William R. Branch

    2017-03-01

    Full Text Available In 1944 Loveridge described two new geckos from Angola Afroedura karroica bogerti and Pachydactylus scutatus angolensis. The descriptions of both species have vague and confusing type localities and refinements are suggested based on early expedition reports historical accounts from the region and a review of cartographic material. Numerous new distribution records are reported for both species from expeditions undertaken from 1956–2016 by the authors or their colleagues. The taxonomic status of both species has changed but new material from diverse habitats altitudes and geological substrates indicates that further taxonomic adjustments are likely in order to reflect additional cryptic diversity.

  17. Effects of salicylates and aminoglycosides on spontaneous otoacoustic emissions in the Tokay gecko.

    Science.gov (United States)

    Stewart, C E; Hudspeth, A J

    2000-01-04

    The high sensitivity and sharp frequency discrimination of hearing depend on mechanical amplification in the cochlea. To explore the basis of this active process, we examined the pharmacological sensitivity of spontaneous otoacoustic emissions (SOAEs) in a lizard, the Tokay gecko. In a quiet environment, each ear produced a complex but stable pattern of emissions. These SOAEs were reversibly modulated by drugs that affect mammalian otoacoustic emissions, the salicylates and the aminoglycoside antibiotics. The effect of a single i.p. injection of sodium salicylate depended on the initial power of the emissions: ears with strong control SOAEs displayed suppression at all frequencies, whereas those with weak control emissions showed enhancement. Repeated oral administration of acetylsalicylic acid reduced all emissions. Single i.p. doses of gentamicin or kanamycin suppressed SOAEs below 2.6 kHz, while modulating those above 2.6 kHz in either of two ways. For ears whose emission power at 2.6-5.2 kHz encompassed more than half of the total, individual emissions displayed facilitation as great as 35-fold. For the remaining ears, emissions dropped to as little as one-sixth of their initial values. The similarity of the responses of reptilian and mammalian cochleas to pharmacological intervention provides further evidence for a common mechanism of cochlear amplification.

  18. Attachment Patterns in the Psychotherapy Relationship: Development of the Client Attachment to Therapist Scale.

    Science.gov (United States)

    Mallinckrodt, Brent; And Others

    1995-01-01

    Describes development of an instrument, the Client Attachment to Therapist Scale (CATS). CATS factors correlated in expected directions with survey measures of object relations, client-rated working alliance, social self-efficacy, and adult attachment. Cluster analysis revealed four types of client attachment. Discusses implications of attachment…

  19. Different perspectives on the sex-attachment link: towards an emotion-motivational account.

    Science.gov (United States)

    Dewitte, Marieke

    2012-01-01

    Although the link between sex and attachment was made decades ago (Hazan & Shaver, 1987), theories on sexual and attachment functioning have been developed in relative isolation. Recent efforts to integrate both literatures have been complicated by the fact that the sex-attachment link has been approached from very different perspectives, including biological, evolutionary, developmental, cognitive, and social psychology approaches. Also, at the empirical level, research on sex and attachment lacks overarching synthesis. This article gives an overview of the most important theoretical ideas and empirical insights on sex and attachment. It starts with describing general models that approach the sex-attachment link from an evolutionary and neurobiological perspective. Then, it summarizes theoretical and empirical ideas of attachment theory and describes how attachment style differences are manifested in intimate and sexual relationships. Research so far has been limited to studying the predicted link between sex and attachment in terms of broad descriptives, and it would benefit the literature to specify the processes and pathways that mediate the sex-attachment link. After a short discussion of the functional similarities between the sexual and the attachment systems, the article describes some specific--dynamical--models that focus on the emotional and cognitive-motivational processes through which attachment schemas influence sexual experiences. Such an emotion-motivational perspective on sex and attachment can help to organize theoretical ideas and empirical findings and eventually promote an integrative view on how attachment dynamics can interact with sexual experiences.

  20. Attachment at (not to) work: applying attachment theory to explain individual behavior in organizations.

    Science.gov (United States)

    Richards, David A; Schat, Aaron C H

    2011-01-01

    In this article, we report the results of 2 studies that were conducted to investigate whether adult attachment theory explains employee behavior at work. In the first study, we examined the structure of a measure of adult attachment and its relations with measures of trait affectivity and the Big Five. In the second study, we examined the relations between dimensions of attachment and emotion regulation behaviors, turnover intentions, and supervisory reports of counterproductive work behavior and organizational citizenship behavior. Results showed that anxiety and avoidance represent 2 higher order dimensions of attachment that predicted these criteria (except for counterproductive work behavior) after controlling for individual difference variables and organizational commitment. The implications of these results for the study of attachment at work are discussed.

  1. Attachment behavior and mother-child conversations as predictors of attachment representations in middle childhood: a longitudinal study.

    Science.gov (United States)

    Dubois-Comtois, Karine; Cyr, Chantal; Moss, Ellen

    2011-07-01

    This study examines longitudinal links between mother-child conversations and attachment patterns in early childhood and later attachment representations. It also tests the role of conversations as mediators in the association between behavioral security and attachment representations. Mother-child conversations (snack-time) and attachment behaviors (Separation-Reunion procedure) were assessed for 83 5.5-year-olds while attachment representations (attachment narratives) were measured at 8.5 years of age. Results showed correspondence between attachment behaviors and representations for secure-confident, ambivalent-preoccupied, and disorganized/controlling-frightened groups. Affective quality of mother-child conversations predicted both child attachment behaviors and representations. Secure and confident children showed greater integration of affective information, ambivalent and preoccupied children more affect exaggeration, and disorganized/controlling and frightened children more chaotic conversations. Avoidant children tended to show more affect minimization in conversations. Finally, mother-child conversations centered on the sharing of emotions and thoughts mediated the relation between behavioral and representational attachment security, which underscores the importance of mother-child conversations in the development of attachment representations in childhood.

  2. Evaluation of Underwater Adhesives and Friction Coatings for In Situ Attachment of Fiber Optic Sensor System for Subsea Applications

    Science.gov (United States)

    Tang, Henry H.; Le, Suy Q.; Orndoff, Evelyne S.; Smith, Frederick D.; Tapia, Alma S.; Brower, David V.

    2012-01-01

    Integrity and performance monitoring of subsea pipelines and structures provides critical information for managing offshore oil and gas production operation and preventing environmentally damaging and costly catastrophic failure. Currently pipeline monitoring devices require ground assembly and installation prior to the underwater deployment of the pipeline. A monitoring device that could be installed in situ on the operating underwater structures could enhance the productivity and improve the safety of current offshore operation. Through a Space Act Agreement (SAA) between the National Aeronautics and Space Administration (NASA) Johnson Space Center (JSC) and Astro Technology, Inc. (ATI), JSC provides technical expertise and testing facilities to support the development of fiber optic sensor technologies by ATI. This paper details the first collaboration effort between NASA JSC and ATI in evaluating underwater applicable adhesives and friction coatings for attaching fiber optic sensor system to subsea pipeline. A market survey was conducted to examine different commercial ]off ]the ]shelf (COTS) underwater adhesive systems and to select adhesive candidates for testing and evaluation. Four COTS epoxy based underwater adhesives were selected and evaluated. The adhesives were applied and cured in simulated seawater conditions and then evaluated for application characteristics and adhesive strength. The adhesive that demonstrated the best underwater application characteristics and highest adhesive strength were identified for further evaluation in developing an attachment system that could be deployed in the harsh subsea environment. Various friction coatings were also tested in this study to measure their shear strengths for a mechanical clamping design concept for attaching fiber optic sensor system. A COTS carbide alloy coating was found to increase the shear strength of metal to metal clamping interface by up to 46 percent. This study provides valuable data for

  3. Attachment, affective temperament, and personality disorders: a study of their relationships in psychiatric outpatients.

    Science.gov (United States)

    MacDonald, Kai; Berlow, Rustin; Thomas, Michael L

    2013-12-01

    As the result of extensive translational and cross-disciplinary research, attachment theory is now a construct with significant neuropsychiatric traction. The correlation of attachment with other influential conceptual models (i.e. temperament and personality) is therefore of interest. Consequently, we explored how two attachment dimensions (attachment anxiety and attachment avoidance) correlated with measures of temperament and personality in 357 psychiatric outpatients. We performed a retrospective review of four questionnaires (the Experiences in Close Relationship scale (ECR-R), Temperament and Character inventory (TCI), Temperament Evaluation of the Memphis, Pisa, Paris and San Diego questionnaire (TEMPS-A), and Personality Self-Portrait Questionnaire (PSQ)). Frequency measures and correlations were examined, as was the predictive value of attachment security for a personality disorder (PD). Significant, robust correlations were found between attachment anxiety and (1) several negative affective temperaments (dysthymic and cyclothymic); (2) several indices of personality pathology (low self-directedness (TCI), DSM-IV paranoid, borderline, histrionic, avoidant and dependent personality traits). Attachment avoidance had fewer large correlations. In an exploratory model, the negative predictive value of attachment security for a PD was 86%. Subjects were a relatively homogeneous subset of ambulatory psychiatric outpatients. PD diagnoses were via self-report. Clinically, these findings highlight the significant overlap between attachment, affective temperament, and personality and support the value of attachment as a screen for PDs. More broadly, given our growing understanding of the neurobiology of attachment (i.e. links with the oxytocin system), these results raise interesting questions about underlying biological systems and psychiatric treatment. © 2013 Elsevier B.V. All rights reserved.

  4. Effects of dynamic coupling between freestanding steel containment and attached piping

    International Nuclear Information System (INIS)

    Kennedy, R.P.; Kincaid, R.H.; Short, S.A.

    1981-01-01

    This paper presents an accurate, practical method of converting uncoupled response time history results obtained from an uncoupled structure model into coupled response time histories using a post-processor routine. The method is rigorous and only requires the modal properties of the uncoupled structure model, the modal properties of the uncoupled attached equipment model, and the uncoupled time histories of the attachment points on the structure. Coupled response spectra or time histories for use as input to an uncoupled equipment model are obtained. Comparisons of coupled versus uncoupled analysis results are presented for representative piping systems attached to a typical BWR Mark III steel containment subjected to vibration from safety relief valve discharge with a fundamental frequency of 12 Hz. It is shown that the coupled response spectra at piping attachment points are reduced by a factor between 2 and 5 from the amplified uncoupled spectra at each significant piping modal frequency above 20 Hz for representative major piping systems attached to the unstiffened portion of the steel shell. Responses at lower frequencies are not generally reduced and may increase by coupling effects for the input loading and shell model studied. Peak accerations are generally significantly reduced while peak displacements may be decreased or increased. Rules are presented for estimating the coupling effects between freestanding steel shells and attached equipment. (orig./HP)

  5. Iodine susceptibility of pseudomonads grown attached to stainless steel surfaces

    Science.gov (United States)

    Pyle, B. H.; McFeters, G. A.

    1990-01-01

    Pseudomonads were adapted to grow in phosphate-buffered water and on stainless steel surfaces to study the iodine sensitivity of attached and planktonic cells. Cultures adapted to low nutrient growth were incubated at room temperature in a circulating reactor system with stainless steel coupons to allow biofilm formation on the metal surfaces. In some experiments, the reactor was partially emptied and refilled with buffer at each sampling time to simulate a "fill-and-draw" water system. Biofilms of attached bacteria, resuspended biofilm bacteria, and reactor suspension, were exposed to 1 mg l-1 iodine for 2 min. Attached bacterial populations which established on coupons within 3 to 5 days displayed a significant increase in resistance to iodine. Increased resistance was also observed for resuspended cells from the biofilm and planktonic bacteria in the system suspension. Generally, intact biofilms and resuspended biofilm cells were most resistant, followed by planktonic bacteria and phosphate buffer cultures. Thus, biofilm formation on stainless steel surfaces within water systems can result in significantly increased disinfection resistance of commonly-occurring water-borne bacteria that may enhance their ability to colonise water treatment and distribution systems.

  6. Father attachment, father emotion expression, and children's attachment to fathers: The role of marital conflict.

    Science.gov (United States)

    Bi, Shuang; Haak, Eric A; Gilbert, Lauren R; El-Sheikh, Mona; Keller, Peggy S

    2018-06-01

    The current study examined relations between father attachment to spouses and child attachment to fathers in middle childhood, focusing on father emotion expressions in father-child interactions as mediators and marital conflict as a moderator of relations. Participants were 199 children between 6 and 12 years of age and their fathers. Fathers completed questionnaires about their attachment to their spouses, and both fathers and mothers reported on their marital conflict. Fathers also discussed a difficult topic with their children for 5 min, and fathers' positive and negative emotion expression during the discussions were coded. Children completed questionnaires through an interview about their attachment to their father. Father insecure attachment interacted with marital conflict in predicting more negative emotions and less positive emotions during father-child interactions. Specifically, in the context of higher marital conflict in this community sample, fathers who reported greater preoccupied attachment to their spouses exhibited more negative emotions and less positive emotions when interacting with their children. In turn, more father negative emotions and less positive emotions were associated with children's less secure attachment to fathers. In contrast, father fearful attachment interacted with marital conflict to predict less negative emotion and more positive emotion during interactions with children. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

  7. A new species of Rock Gecko of the genus Cnemaspis Strauch, 1887 (Squamata: Gekkonidae) from Belitung Island, Indonesia.

    Science.gov (United States)

    Riyanto, Awal; Hamidy, Amir; Sidik, Irvan; Gunalen, Danny

    2017-11-30

    A new species of rock gecko of the genus Cnemaspis Strauch is described from Belitung Island, Indonesia. The new species is differentiated from all other species in the Southern Sunda clade (sensu Grismer et al. 2014a) by having a unique combination of characters including: (1) a maximum SVL of 54.1 mm, (2) five or six postmental scales, (3) enlarged submetacarpal scales on the first finger, (4) enlarged submetatarsal scales on the first toe, (5) keeled ventral scales, (6) absence of precloacal pores, (7) absence of enlarged femoral scales, (8) absence of shield-like subtibial scales, (9) caudal tubercles encircling the tail, (10) an interrupted median row of enlarged keeled subcaudals, (11) presence of a distinct furrow on the lateral surface of the tail (12) 22-24 lamellae beneath fourth toe, and (13) two postcloacal tubercles on each side of the tail base.

  8. Eating disorders in adolescence: attachment issues from a developmental perspective

    Directory of Open Access Journals (Sweden)

    Manuela eGander

    2015-08-01

    Full Text Available In the present article we review findings from an emerging body of research on attachment issues in adolescents with eating disorders from a developmental perspective. First, we will outline the crucial developmental changes in the attachment system and discuss how they might be related to the early onset of the disease. Then we will report on the major results from attachment studies using self-report and narrative instruments in that age group. Studies with a developmental approach on attachment will be analyzed in more detail. The high incidence of the unresolved attachment pattern in eating disorder samples is striking, especially for patients with anorexia nervosa. Interestingly, this predominance of the unresolved category was also found in their mothers. To date, these transgenerational aspects are still poorly understood and therefore represent an exciting research frontier. Future studies that include larger adolescent samples and provide a more detailed description including symptom severity and comorbidity would contribute to a better understanding of this complex and painful condition.

  9. Attachment within life history theory: an evolutionary perspective on individual differences in attachment.

    Science.gov (United States)

    Szepsenwol, Ohad; Simpson, Jeffry A

    2018-03-15

    In this article, we discuss theory and research on how individual differences in adult attachment mediate the adaptive calibration of reproductive strategies, cognitive schemas, and emotional expression and regulation. We first present an integration of attachment theory and life history theory. Then, we discuss how early harsh and/or unpredictable environments may promote insecure attachment by hampering parents' ability to provide sensitive and reliable care to their children. Finally, we discuss how, in the context of harsh and/or unpredictable environments, different types of insecure attachment (i.e. anxiety and avoidance) may promote evolutionary adaptive reproductive strategies, cognitive schemas, and emotional expression and regulation profiles. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Attachment, neurobiology, and mentalizing along the psychosis continuum

    Directory of Open Access Journals (Sweden)

    Martin Debbané

    2016-08-01

    Full Text Available In this review article, we outline the evidence linking attachment adversity to the psychosis, from the premorbid stages of the disorder to its clinical forms. To better understand the neurobiological mechanisms through which insecure attachment may contribute to psychosis, we identify at least five neurobiological pathways linking attachment to risk for developing psychosis. Besides its well documented influence on the hypothalamic-pituary-adrenal (HPA axis, insecure attachment may also contribute to neurodevelopmental risk through the dopaminergic and oxytonergic systems, as well as bear influence on neuroinflammation and oxidative stress responses. We further consider the neuroscientific and behavioural studies that underpin mentalization as a suite of processes potentially moderating the risk to transition to psychotic disorders. In particular, mentalization may help the individual compensate for endophenotypical impairments in the integration of sensory and metacognitive information. We propose a model where embodied mentalization would lie at the core of a protective, resilience response mitigating the adverse and potentially pathological influence of the neurodevelopmental cascade of risk for psychosis.

  11. Antecedents of maternal parenting stress: the role of attachment style, prenatal attachment, and dyadic adjustment in first-time mothers.

    Science.gov (United States)

    Mazzeschi, Claudia; Pazzagli, Chiara; Radi, Giulia; Raspa, Veronica; Buratta, Livia

    2015-01-01

    The transition to parenthood is widely considered a period of increased vulnerability often accompanied by stress. Abidin conceived parenting stress as referring to specific difficulties in adjusting to the parenting role. Most studies of psychological distress arising from the demands of parenting have investigated the impact of stress on the development of dysfunctional parent-child relationships and on adult and child psychopathology. Studies have largely focused on mothers' postnatal experience; less attention has been devoted to maternal prenatal characteristics associated with subsequent parental stress and studies of maternal prenatal predictors are few. Furthermore, no studies have examined that association exclusively with samples of first-time mothers. With an observational prospective study design with two time periods, the aim of this study was to investigate the role of mothers' attachment style, maternal prenatal attachment to the fetus and dyadic adjustment during pregnancy (7th months of gestation) and their potential unique contribution to parenting stress 3 months after childbirth in a sample of nulliparous women. Results showed significant correlations between antenatal measures. Maternal attachment style (especially relationship anxiety) was negatively correlated with prenatal attachment and with dyadic adjustment; positive correlations resulted between prenatal attachment and dyadic adjustment. Each of the investigated variables was also good predictor of parenting stress 3 months after childbirth. Findings suggested how these dimensions could be considered as risk factors in the transition to motherhood and in the very beginning of the emergence of the caregiving system, especially with first-time mothers.

  12. Activating Attachments Reduces Memories of Traumatic Images.

    Directory of Open Access Journals (Sweden)

    Richard A Bryant

    Full Text Available Emotional memories, and especially intrusive memories, are a common feature of many psychological disorders, and are overconsolidated by stress. Attachment theory posits that activation of mental representations of attachment figures can reduce stress and boost coping. This