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Sample records for gecko attachment system

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

    PubMed

    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. The pupils and optical systems of gecko eyes.

    PubMed

    Roth, Lina S V; Lundström, Linda; Kelber, Almut; Kröger, Ronald H H; Unsbo, Peter

    2009-03-30

    The nocturnal helmet gecko, Tarentola chazaliae, discriminates colors in dim moonlight when humans are color blind. The sensitivity of the helmet gecko eye has been calculated to be 350 times higher than human cone vision at the color vision threshold. The optics and the large cones of the gecko are important reasons why they can use color vision at low light intensities. Using photorefractometry and an adapted laboratory Hartmann-Shack wavefront sensor of high resolution, we also show that the optical system of the helmet gecko has distinct concentric zones of different refractive powers, a so-called multifocal optical system. The intraspecific variation is large but in most of the individuals studied the zones differed by 15 diopters. This is of the same magnitude as needed to focus light of the wavelength range to which gecko photoreceptors are most sensitive. We compare the optical system of the helmet gecko to that of the diurnal day gecko, Phelsuma madagascariensis grandis. The optical system of the day gecko shows no signs of distinct concentric zones and is thereby monofocal.

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

    PubMed

    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. The effect of water on the gecko adhesive system

    NASA Astrophysics Data System (ADS)

    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

  5. A ZZ/ZW sex chromosome system in the thick-tailed Gecko ( Underwoodisaurus milii; Squamata: Gekkota: Carphodactylidae), a member of the ancient gecko lineage.

    PubMed

    Pokorná, M; Rens, W; Rovatsos, M; Kratochvíl, L

    2014-01-01

    Geckos (Gekkota) are a highly diversified group of lizards with an exceptional diversity in sex-determining systems. Despite this intriguing documented variability, data on sex determination in many lineages is still scarce. Here, we document the previously overlooked heteromorphic ZZ/ZW sex chromosomes in the thick-tailed gecko, Underwoodisaurus milii, a member of the ancient lineage of pygopodoid geckos. The finding of female heterogamety within pygopodoid geckos was unexpected, as until now only male heterogamety and environmental sex determination have been reported in this group, and female heterogamety was known only in distantly related gecko families separated from the pygopodoid geckos around 150 million years ago. The W chromosome in U. milii is highly heterochromatic and contains a large number of telomeric-like repeats comparable to around 50% of all telomeric-like sequences present in male genomes. The accumulation of these repeats might have been responsible for the considerable size expansion of the W chromosome in comparison to the Z chromosome. The heteromorphic ZZ/ZW sex chromosomes with accumulated telomeric-like repeats in the thick-tailed geckos further illustrate the exceptional diversity of sex-determining systems in geckos and add important information to our understanding of the evolution and phylogeny of sex-determining systems in reptiles.

  6. Instantly switchable adhesion of bridged fibrillar adhesive via gecko-inspired detachment mechanism and its application to a transportation system.

    PubMed

    Bae, Won-Gyu; Kim, Doogon; Suh, Kahp-Yang

    2013-12-07

    Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the climbing behaviour of gecko lizards. The adhesive shows strong normal attachment (~30 N cm(-2)) as well as easy and fast detachment within 0.5 s without involving complex dynamic mechanisms or specific stimulus-responsive materials. The fabrication of the bridged micropillars consists of replica moulding of polydimethylsiloxane (PDMS) micropillars, transfer of the PDMS precursor to the heads of the micropillars, and inverse placement on an inert Teflon-coated surface. Owing to the spontaneous interconnections of low viscosity PDMS precursor, bridged micropillars with a uniform capping nanomembrane (~800 nm thickness) are formed over a large area. Interestingly, macroscopic adhesion in the normal direction can be immediately switched between on and off states by changing the two detachment modes of pulling and peeling, respectively. To prove the potential of the fibrillar adhesive for practical use, an automated transportation system is demonstrated for lifting and releasing a mass of stacked glass slides over 1000 cycles of attachment and detachment.

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

    NASA Astrophysics Data System (ADS)

    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

  8. Instantly switchable adhesion of bridged fibrillar adhesive via gecko-inspired detachment mechanism and its application to a transportation system

    NASA Astrophysics Data System (ADS)

    Bae, Won-Gyu; Kim, Doogon; Suh, Kahp-Yang

    2013-11-01

    Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the climbing behaviour of gecko lizards. The adhesive shows strong normal attachment (~30 N cm-2) as well as easy and fast detachment within 0.5 s without involving complex dynamic mechanisms or specific stimulus-responsive materials. The fabrication of the bridged micropillars consists of replica moulding of polydimethylsiloxane (PDMS) micropillars, transfer of the PDMS precursor to the heads of the micropillars, and inverse placement on an inert Teflon-coated surface. Owing to the spontaneous interconnections of low viscosity PDMS precursor, bridged micropillars with a uniform capping nanomembrane (~800 nm thickness) are formed over a large area. Interestingly, macroscopic adhesion in the normal direction can be immediately switched between on and off states by changing the two detachment modes of pulling and peeling, respectively. To prove the potential of the fibrillar adhesive for practical use, an automated transportation system is demonstrated for lifting and releasing a mass of stacked glass slides over 1000 cycles of attachment and detachment.Inspired by the exceptional climbing ability of gecko lizards, artificial fibrillar adhesives have been extensively studied over the last decade both experimentally and theoretically. Therefore, a new leap towards practical uses beyond the academic horizon is timely and highly anticipated. To this end, we present a fibrillar adhesive in the form of bridged micropillars and its application to a transportation system with the detachment mechanism inspired by the

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

    PubMed Central

    Stewart, William J.; Higham, Timothy E.

    2014-01-01

    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. PMID:25472940

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

    PubMed

    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.

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

    PubMed

    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.

  12. Calcium-Binding Protein Immunoreactivity Characterizes the Auditory System of Gekko gecko

    PubMed Central

    Yan, Kai; Tang, Ye-Zhong; Carr, Catherine E.

    2011-01-01

    Geckos use vocalizations for intraspecific communication, but little is known about the organization of their central auditory system. We therefore used antibodies against the calcium-binding proteins calretinin (CR), parvalbumin (PV), and calbindin-D28k (CB) to characterize the gecko auditory system. We also examined expression of both glutamic acid decarboxlase (GAD) and synaptic vesicle protein (SV2). Western blots showed that these antibodies are specific to gecko brain. All three calcium-binding proteins were expressed in the auditory nerve, and CR immunoreactivity labeled the first-order nuclei and delineated the terminal fields associated with the ascending projections from the first-order auditory nuclei. PV expression characterized the superior olivary nuclei, whereas GAD immunoreactivity characterized many neurons in the nucleus of the lateral lemniscus and some neurons in the torus semicircularis. In the auditory midbrain, the distribution of CR, PV, and CB characterized divisions within the central nucleus of the torus semicircularis. All three calcium-binding proteins were expressed in nucleus medialis of the thalamus. These expression patterns are similar to those described for other vertebrates. PMID:20589907

  13. Ceramic blade attachment system

    DOEpatents

    Boyd, G.L.

    1994-12-13

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a pair of recessed portions thereon. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings have a pair of grooves therein in which are positioned a pair of pins having a generally rectangular cross-section and a reaction surface thereon. A pair of cylindrical rollers interposed respective ones of the pair of reaction surfaces and the pair of recessed portions. The attachment system or turbine assembly provides an economical, reliable and effective attachment of a component having a preestablished rate of thermal expansion to a component having a greater preestablished rate of thermal expansion. 3 figures.

  14. Ceramic blade attachment system

    DOEpatents

    Boyd, Gary L.

    1994-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a pair of recessed portions thereon. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings have a pair of grooves therein in which are positioned a pair of pins having a generally rectangular cross-section and a reaction surface thereon. A pair of cylindrical rollers interposed respective ones of the pair of reaction surfaces and the pair of recessed portions. The attachment system or turbine assembly provides an economical, reliable and effective attachment of a component having a preestablished rate of thermal expansion to a component having a greater preestablished rate of thermal expansion.

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

    PubMed

    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

  16. Belt attachment and system

    DOEpatents

    Schneider, Abraham D.; Davidson, Erick M.

    2016-02-02

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Influence of substrate modulus on gecko adhesion.

    PubMed

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

    2017-03-13

    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).

  19. Influence of substrate modulus on gecko adhesion

    NASA Astrophysics Data System (ADS)

    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).

  20. Influence of substrate modulus on gecko adhesion

    PubMed Central

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

    2017-01-01

    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). PMID:28287647

  1. Turbine nozzle attachment system

    DOEpatents

    Norton, P.F.; Shaffer, J.E.

    1995-10-24

    A nozzle guide vane assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and is attached to conventional metallic components. The nozzle guide vane assembly includes a pair of legs extending radially outwardly from an outer shroud and a pair of mounting legs extending radially inwardly from an inner shroud. Each of the pair of legs and mounting legs have a pair of holes therein. A plurality of members attached to the gas turbine engine have a plurality of bores therein which axially align with corresponding ones of the pair of holes in the legs. A plurality of pins are positioned within the corresponding holes and bores radially positioning the nozzle guide vane assembly about a central axis of the gas turbine engine. 3 figs.

  2. Turbine nozzle attachment system

    DOEpatents

    Norton, Paul F.; Shaffer, James E.

    1995-01-01

    A nozzle guide vane assembly having a preestablished rate of thermal expansion is positioned in a gas turbine engine and being attached to conventional metallic components. The nozzle guide vane assembly includes a pair of legs extending radially outwardly from an outer shroud and a pair of mounting legs extending radially inwardly from an inner shroud. Each of the pair of legs and mounting legs have a pair of holes therein. A plurality of members attached to the gas turbine engine have a plurality of bores therein which axially align with corresponding ones of the pair of holes in the legs. A plurality of pins are positioned within the corresponding holes and bores radially positioning the nozzle guide vane assembly about a central axis of the gas turbine engine.

  3. The effect of temperature and humidity on adhesion of a gecko-inspired adhesive: implications for the natural system.

    PubMed

    Stark, Alyssa Y; Klittich, Mena R; Sitti, Metin; Niewiarowski, Peter H; Dhinojwala, Ali

    2016-08-02

    The adhesive system of geckos has inspired hundreds of synthetic adhesives. While this system has been used relentlessly as a source of inspiration, less work has been done in reverse, where synthetics are used to test questions and hypotheses about the natural system. Here we take such an approach. We tested shear adhesion of a mushroom-tipped synthetic gecko adhesive under conditions that produced perplexing results in the natural adhesive system. Synthetic samples were tested at two temperatures (12 °C and 32 °C) and four different humidity levels (30%, 55%, 70%, and 80% RH). Surprisingly, adhesive performance of the synthetic samples matched that of living geckos, suggesting that uncontrolled parameters in the natural system, such as surface chemistry and material changes, may not be as influential in whole-animal performance as previously thought. There was one difference, however, when comparing natural and synthetic adhesive performance. At 12 °C and 80% RH, adhesion of the synthetic structures was lower than expected based on the natural system's performance. Our approach highlights a unique opportunity for both biologists and material scientists, where new questions and hypotheses can be fueled by joint comparisons of the natural and synthetic systems, ultimately improving knowledge of both.

  4. The effect of temperature and humidity on adhesion of a gecko-inspired adhesive: implications for the natural system

    PubMed Central

    Stark, Alyssa Y.; Klittich, Mena R.; Sitti, Metin; Niewiarowski, Peter H.; Dhinojwala, Ali

    2016-01-01

    The adhesive system of geckos has inspired hundreds of synthetic adhesives. While this system has been used relentlessly as a source of inspiration, less work has been done in reverse, where synthetics are used to test questions and hypotheses about the natural system. Here we take such an approach. We tested shear adhesion of a mushroom-tipped synthetic gecko adhesive under conditions that produced perplexing results in the natural adhesive system. Synthetic samples were tested at two temperatures (12 °C and 32 °C) and four different humidity levels (30%, 55%, 70%, and 80% RH). Surprisingly, adhesive performance of the synthetic samples matched that of living geckos, suggesting that uncontrolled parameters in the natural system, such as surface chemistry and material changes, may not be as influential in whole-animal performance as previously thought. There was one difference, however, when comparing natural and synthetic adhesive performance. At 12 °C and 80% RH, adhesion of the synthetic structures was lower than expected based on the natural system’s performance. Our approach highlights a unique opportunity for both biologists and material scientists, where new questions and hypotheses can be fueled by joint comparisons of the natural and synthetic systems, ultimately improving knowledge of both. PMID:27480603

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

    PubMed Central

    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

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

    PubMed

    Russell, Anthony P; Higham, Timothy E

    2009-10-22

    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 degrees 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 degrees 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.

  7. Evidence for capillarity contributions to gecko adhesion from single spatula nanomechanical measurements.

    PubMed

    Huber, Gerrit; Mantz, Hubert; Spolenak, Ralph; Mecke, Klaus; Jacobs, Karin; Gorb, Stanislav N; Arzt, Eduard

    2005-11-08

    The hairy attachment system on a gecko's toes, consisting of one billion spatulae in the case of Gekko gecko [Ruibal, R. & Ernst, V. (1965) J. Morphol. 117, 271-294], allows it to adhere to nearly all surface topographies. The mechanistic basis for gecko adhesion has been intensely investigated, but the lowest hierarchical level, that of the spatula, has become experimentally accessible only recently. This report details measurements of the adhesion force exerted by a single gecko spatula for various atmospheric conditions and surface chemistries. Through judicious choice and modification of substrates, the short- and long-range adhesive forces are separated. In contrast to previous work [Autumn, K., Sitti, M., Liang, Y. C. A., Peattie, A. M., Hansen, W. R., Sponberg, S., Kenny, T. W., Fearing, R., Israelachvili, J. N. & Full, R. J. (2002) Proc. Natl. Acad. Sci. USA 99, 12252-12256], our measurements clearly show that humidity contributes significantly to gecko adhesion on a nanoscopic level. These findings are crucial for the development of artificial biomimetic attachment systems.

  8. Ceramic blade attachment system

    DOEpatents

    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.

  9. Ceramic blade attachment system

    DOEpatents

    Frey, deceased, Gary A.; Jimenez, Oscar D.

    1996-01-01

    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 therebetween. 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. And, 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.

  10. Ceramic blade attachment system

    DOEpatents

    Shaffer, J.E.

    1995-01-10

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a first groove and a second groove therein. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings has a first groove and a second groove therein. The space or void formed between the first grooves and the second grooves has a plurality of spherical balls positioned therein. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade. 4 figures.

  11. Ceramic blade attachment system

    DOEpatents

    Shaffer, James E.

    1995-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine wheel having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade. The turbine blade has a root portion having a first groove and a second groove therein. The turbine wheel includes a plurality of openings in which the turbine blade is positioned. Each of the openings has a first groove and a second groove therein. The space or void formed between the first grooves and the second grooves has a plurality of spherical balls positioned therein. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade.

  12. Ceramic blade attachment system

    DOEpatents

    Shaffer, James E.

    1995-01-01

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine disc having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade and forms a turbine assembly. The turbine blade has a root portion defining a pair of sides having a pair of grooves therein. The turbine assembly includes a pair of flanges between which the turbine blades are positioned. Each of the pair of flanges has a plurality of grooves defined therein. The grooves within the pair of flanges are aligned with the grooves in the blades and have a space formed therebetween. A plurality of spherical balls are positioned within the space. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade.

  13. Ceramic blade attachment system

    DOEpatents

    Shaffer, J.E.

    1995-07-11

    A turbine blade having a preestablished rate of thermal expansion is attached to a turbine disc having a preestablished rate of thermal expansion being greater than the preestablished rate of thermal expansion of the turbine blade and forms a turbine assembly. The turbine blade has a root portion defining a pair of sides having a pair of grooves therein. The turbine assembly includes a pair of flanges between which the turbine blades are positioned. Each of the pair of flanges has a plurality of grooves defined therein. The grooves within the pair of flanges are aligned with the grooves in the blades and have a space formed therebetween. A plurality of spherical balls are positioned within the space. The plurality of spherical balls has a preestablished rate of thermal expansion being equal to the preestablished rate of thermal expansion of the turbine blade. 4 figs.

  14. Carbon Nanotube-Based Synthetic Gecko Tapes

    NASA Astrophysics Data System (ADS)

    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.

  15. Mechanics of robust and releasable adhesion in biology: Bottom up designed hierarchical structures of gecko

    NASA Astrophysics Data System (ADS)

    Yao, Haimin; Gao, Huajian

    2006-06-01

    Gecko and many insects have evolved specialized adhesive tissues with bottom-up designed (from nanoscale and up) hierarchical structures that allow them to maneuver on vertical walls and ceilings. The adhesion mechanisms of gecko must be robust enough to function on unknown rough surfaces and also easily releasable upon animal movement. How does nature design such macroscopic sized robust and releasable adhesion devices? How can an adhesion system designed for robust attachment simultaneously allow easy detachment? These questions have motivated the present investigation on mechanics of robust and releasable adhesion in biology. On the question of robust adhesion, we introduce a fractal gecko hairs model, which assumes self-similar fibrillar structures at multiple hierarchical levels mimicking gecko's spatula ultrastructure, to show that structural hierarchy plays a key role in robust adhesion: it allows the work of adhesion to be exponentially enhanced with each added level of hierarchy. We demonstrate that, barring fiber fracture, the fractal gecko hairs can be designed from nanoscale and up to achieve flaw tolerant adhesion at any length scales. However, consideration of crack-like flaws in the hairs themselves results in an upper size limit for flaw tolerant design. On the question of releasable adhesion, we hypothesize that the asymmetrically aligned seta hairs of gecko form a strongly anisotropic material with adhesion strength strongly varying with the direction of pulling. We use analytical solutions to show that a strongly anisotropic elastic solid indeed exhibits a strongly anisotropic adhesion strength when sticking on a rough surface. Furthermore, we perform finite element calculations to show that the adhesion strength of a strongly anisotropic attachment pad exhibits essentially two levels of adhesion strength depending on the direction of pulling, resulting in an orientation-controlled switch between attachment and detachment. These findings not only

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

  18. Microfabricated adhesive mimicking gecko foot-hair

    NASA Astrophysics Data System (ADS)

    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.

  19. How Do Geckos Stick?

    ERIC Educational Resources Information Center

    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…

  20. How Do Geckos Stick?

    ERIC Educational Resources Information Center

    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…

  1. Hot-Melt Adhesive Attachment System

    NASA Technical Reports Server (NTRS)

    Fox, R. L.; Frizzell, A. W.; Little, B. D.; Progar, D. J.; Coultrip, R. H.; Couch, R. H.; Stein, B. A.; Buckley, J. D.; St. Clair, T. L.; Gleason, J. R.

    1983-01-01

    Adhesive system is as effective on Earth as in space. Fiberglass cloth mounted in head assembly. When adhesive reaches melt temperature head is attached to metals composites, ceramics, and other materials. Once attached, head cooled rapidly for quick stick. Used to tether tools or attach temporary scaffolding to walls, buildings, or beams.

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

    PubMed Central

    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

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

    PubMed

    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.

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

    PubMed

    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.

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

    PubMed Central

    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 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 cm2 of adhesive per hand. PMID:25411404

  6. Intestinal bacterial flora of the household lizard, Gecko gecko.

    PubMed

    Tan, R J; Lim, E W; Ishak, B

    1978-03-01

    A total of 114 isolates was recovered from the intestines of 43 househould lizards, Gecko gecko. Among the important ones were Staphylococcus aureus, Salmonella typhimurium, Pseudomonas aeruginosa, Proteus mirabilis and Edwardsiella tarda.

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

    PubMed

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

    PubMed Central

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

    2014-01-01

    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. PMID:24554579

  9. The effect of surface water and wetting on gecko adhesion.

    PubMed

    Stark, Alyssa Y; Sullivan, Timothy W; Niewiarowski, Peter H

    2012-09-01

    Despite profound interest in the mechanics and performance of the gecko adhesive system, relatively few studies have focused on performance under conditions that are ecologically relevant to the natural habitats of geckos. Because geckos are likely to encounter surfaces that are wet, we used shear force adhesion measurements to examine the effect of surface water and toe pad wetting on the whole-animal performance of a tropical-dwelling gecko (Gekko gecko). To test the effect of surface wetting, we measured the shear adhesive force of geckos on three substrate conditions: dry glass, glass misted with water droplets and glass fully submerged in water. We also investigated the effect of wetting on the adhesive toe pad by soaking the toe pads prior to testing. Finally, we tested for repeatability of the adhesive system in each wetting condition by measuring shear adhesion after each step a gecko made under treatment conditions. Wetted toe pads had significantly lower shear adhesive force in all treatments (0.86 ± 0.09 N) than the control (17.96 ± 3.42 N), as did full immersion in water (0.44 ± 0.03 N). Treatments with droplets of water distributed across the surface were more variable and did not differ from treatments where the surface was dry (4.72 ± 1.59 N misted glass; 9.76 ± 2.81 N dry glass), except after the gecko took multiple steps. These findings suggest that surface water and the wetting of a gecko's adhesive toe pads may have significant consequences for the ecology and behavior of geckos living in tropical environments.

  10. Nuclear reactor fuel rod attachment system

    DOEpatents

    Not Available

    1980-09-17

    A reusable system is described 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. The locking cap has two opposing fingers 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.

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

    PubMed

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

    2015-02-04

    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.

  12. Restriction Site-Associated DNA Sequencing (RAD-seq) Reveals an Extraordinary Number of Transitions among Gecko Sex-Determining Systems.

    PubMed

    Gamble, Tony; Coryell, Jessi; Ezaz, Tariq; Lynch, Joshua; Scantlebury, Daniel P; Zarkower, David

    2015-05-01

    Sex chromosomes have evolved many times in animals and studying these replicate evolutionary "experiments" can help broaden our understanding of the general forces driving the origin and evolution of sex chromosomes. However this plan of study has been hindered by the inability to identify the sex chromosome systems in the large number of species with cryptic, homomorphic sex chromosomes. Restriction site-associated DNA sequencing (RAD-seq) is a critical enabling technology that can identify the sex chromosome systems in many species where traditional cytogenetic methods have failed. Using newly generated RAD-seq data from 12 gecko species, along with data from the literature, we reinterpret the evolution of sex-determining systems in lizards and snakes and test the hypothesis that sex chromosomes can routinely act as evolutionary traps. We uncovered between 17 and 25 transitions among gecko sex-determining systems. This is approximately one-half to two-thirds of the total number of transitions observed among all lizards and snakes. We find support for the hypothesis that sex chromosome systems can readily become trap-like and show that adding even a small number of species from understudied clades can greatly enhance hypothesis testing in a model-based phylogenetic framework. RAD-seq will undoubtedly prove useful in evaluating other species for male or female heterogamety, particularly the majority of fish, amphibian, and reptile species that lack visibly heteromorphic sex chromosomes, and will significantly accelerate the pace of biological discovery.

  13. Family systems theory, attachment theory, and culture.

    PubMed

    Rothbaum, Fred; Rosen, Karen; Ujiie, Tatsuo; Uchida, Nobuko

    2002-01-01

    Family systems theory and attachment theory have important similarities and complementarities. Here we consider two areas in which the theories converge: (a) in family system theorists' description of an overly close, or "enmeshed," mother-child dyad, which attachment theorists conceptualize as the interaction of children's ambivalent attachment and mothers' preoccupied attachment; (b) in family system theorists' description of the "pursuer-distance cycle" of marital conflict, which attachment theorists conceptualize as the interaction of preoccupied and dismissive partners. We briefly review family systems theory evidence, and more extensively review attachment theory evidence, pertaining to these points of convergence. We also review cross-cultural research, which leads us to conclude that the dynamics described in both theories reflect, in part, Western ways of thinking and Western patterns of relatedness. Evidence from Japan suggests that extremely close ties between mother and child are perceived as adaptive, and are more common, and that children experience less adverse effects from such relationships than do children in the West. Moreover, in Japan there is less emphasis on the importance of the exclusive spousal relationship, and less need for the mother and father to find time alone to rekindle romantic, intimate feelings and to resolve conflicts by openly communicating their differences. Thus, the "maladaptive" pattern frequently cited by Western theorists of an extremely close mother-child relationship, an unromantic, conflictual marriage characterized by little verbal communication and a peripheral, distant father, may function very differently in other cultures. While we believe that both theories will be greatly enriched by their integration, we caution against the application of either theory outside the cultures in which they were developed.

  14. Nuclear reactor fuel rod attachment system

    DOEpatents

    Christiansen, David W.

    1982-01-01

    A reusable system for removably attaching a nuclear reactor fuel rod (12) to a support member (14). A locking cap (22) is secured to the fuel rod (12) and a locking strip (24) is fastened to the support member (14). The locking cap (22) has two opposing fingers (24a and 24b) shaped to form a socket having a body portion (26). The locking strip has an extension (36) shaped to rigidly attach to the socket's body portion (26). The locking cap's fingers are resiliently deflectable. For attachment, the locking cap (22) is longitudinally pushed onto the locking strip (24) causing the extension (36) to temporarily deflect open the fingers (24a and 24b) to engage the socket's body portion (26). For removal, the process is reversed.

  15. Correlates of Attachment at Age 3: Construct Validity of the Preschool Attachment Classification System

    ERIC Educational Resources Information Center

    Moss, Ellen; Bureau, Jean-Francois; Cyr, Chantal; Mongeau, Chantal; St-Laurent, Diane

    2004-01-01

    This study examined correlates of attachment at age 3 to further validate preschool separation-reunion measures. Three-year-olds (N = 150) and their mothers participated in a separation-reunion protocol, the Preschool Attachment Classification System (PACS: J. Cassidy & R. S. Marvin with the MacArthur Working Group on Attachment, 1992), and a…

  16. Frictional and elastic energy in gecko adhesive detachment.

    PubMed

    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.

  17. Assessing Attachment in Psychotherapy: Validation of the Patient Attachment Coding System (PACS).

    PubMed

    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 by monitoring clients' verbal activity. These results also provide information regarding the ways in which differences in attachment status play out in therapy sessions and further the study of attachment in psychotherapy from a pre-treatment client factor to a process variable. Copyright © 2015 John Wiley & Sons, Ltd. The Patient Attachment Coding System is a valid measure of attachment that can classify clients' attachment based on any single psychotherapy transcript, in many therapeutic modalities Client differences in attachment manifest in part independently of the therapist's contributions Client adult attachment patterns are likely to affect psychotherapeutic processes. Copyright © 2015 John Wiley & Sons, Ltd.

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

    PubMed

    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.

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

    PubMed

    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.

  20. Nocturnal colour vision in geckos.

    PubMed Central

    Roth, Lina S V; Kelber, Almut

    2004-01-01

    Nocturnal animals are said to sacrifice colour vision in favour of increased absolute sensitivity. This is true for most vertebrates that possess a dual retina with a single type of rod for colour-blind night vision and multiple types of cone for diurnal colour vision. However, among the nocturnal vertebrates, geckos are unusual because they have no rods but three cone types. Here, we show that geckos use their cones for colour vision in dim light. Two specimens of the nocturnal helmet gecko Tarentola (formerly Geckonia) chazaliae were able to discriminate blue from grey patterns by colour alone. Experiments were performed at 0.002 cd m(-2), a light intensity similar to dim moonlight. We conclude that nocturnal geckos can use cone-based colour vision at very dim light levels when humans rely on colour-blind rod vision. PMID:15801611

  1. Nocturnal colour vision in geckos.

    PubMed

    Roth, Lina S V; Kelber, Almut

    2004-12-07

    Nocturnal animals are said to sacrifice colour vision in favour of increased absolute sensitivity. This is true for most vertebrates that possess a dual retina with a single type of rod for colour-blind night vision and multiple types of cone for diurnal colour vision. However, among the nocturnal vertebrates, geckos are unusual because they have no rods but three cone types. Here, we show that geckos use their cones for colour vision in dim light. Two specimens of the nocturnal helmet gecko Tarentola (formerly Geckonia) chazaliae were able to discriminate blue from grey patterns by colour alone. Experiments were performed at 0.002 cd m(-2), a light intensity similar to dim moonlight. We conclude that nocturnal geckos can use cone-based colour vision at very dim light levels when humans rely on colour-blind rod vision.

  2. Efficient active actuation to imitate locomotion of gecko's toes using an ionic polymer-metal composite actuator enhanced by carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Yu, Min; He, Qingsong; Yu, Dingshan; Zhang, Xiaoqing; Ji, Aihong; Zhang, Hao; Guo, Ce; Dai, Zhendong

    2012-10-01

    Active actuation of the adhesive pads is important for a gecko-robot climbing on walls. We demonstrate the fabrication of an ionic polymer-metal composite (IPMC) actuator enhanced with carbon nanotubes (CNTs) and its use for actively actuating an adhesive array to imitate the locomotion of gecko's toes. The as-fabricated IPMC actuator doped with CNTs exhibits a maximum blocking force of 3.59 gf driven at a low voltage of 3 V. It can be easily controlled by voltage signals to actuate an artificial gecko's toe to attach and detach from a surface. This will allow active, distributed actuation in a gecko robot.

  3. Reduction of water surface tension significantly impacts gecko adhesion underwater.

    PubMed

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

    2014-12-01

    The gecko adhesive system is dependent on weak van der Waals interactions that are multiplied across thousands of fine hair-like structures (setae) on geckos' toe pads. Due to the requirements of van der Waals forces, we expect that any interruption between the setae and substrate, such as a water layer, will compromise adhesion. Our recent results suggest, however, that the air layer (plastron) surrounding the superhydrophobic toe pads aid in expelling water at the contact interface and create strong shear adhesion in water when in contact with hydrophobic surfaces. To test the function of the air plastron, we reduced the surface tension of water using two surfactants, a charged anionic surfactant and a neutral nonionic surfactant. We tested geckos on three substrates: hydrophilic glass and two hydrophobic surfaces, glass with a octadecyl trichlorosilane self-assembled monolayer (OTS-SAM) and polytetrafluoroethylene (PTFE). We found that the anionic surfactant inhibited the formation of the air plastron layer and significantly reduced shear adhesion to all three substrates. Interestingly, the air plastron was more stable in the nonionic surfactant treatments than the anionic surfactant treatments and we found that geckos adhered better in the nonionic surfactant than in the anionic surfactant on OTS-SAM and PTFE but not on glass. Our results have implications for the evolution of a superhydrophobic toe pad and highlight some of the challenges faced in designing synthetic adhesives that mimic geckos' toes.

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

    PubMed

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

  7. Assessing Attachment Representations in Adolescents: Discriminant Validation of the Adult Attachment Projective Picture System.

    PubMed

    Gander, Manuela; George, Carol; Pokorny, Dan; Buchheim, Anna

    2017-04-01

    The contribution of attachment to human development and clinical risk is well established for children and adults, yet there is relatively limited knowledge about attachment in adolescence due to the poor availability of construct valid measures. The Adult Attachment Projective Picture System (AAP) is a reliable and valid instrument to assess adult attachment status. This study examines for the first time the discriminant validity of the AAP in adolescents. In our sample of 79 teenagers between 15 and 18 years, 42 % were classified as secure, 34 % as insecure-dismissing, 13 % as insecure-preoccupied and 11 % as unresolved. The results demonstrated discriminant validity for using the AAP in that age group, with no associations between attachment classifications and verbal intelligence, social desirability, story length or sociodemographic variables. These results poise the AAP to be used in clinical intervention and large-scale research investigating normative and atypical developmental correlates and sequelae of attachment, including psychopathology in adolescence.

  8. Structure, attachment properties, and ecological importance of the attachment system of English ivy (Hedera helix)

    PubMed Central

    Melzer, Björn; Seidel, Robin; Steinbrecher, Tina; Speck, Thomas

    2012-01-01

    Root climbers such as English ivy (Hedera helix) rely on specialized adventitious roots for attachment, enabling the plants to climb on a wide range of natural and artificial substrates. Despite their importance for the climbing habit, the biomechanical properties of these specialized adventitious roots compared with standard roots and their performance in the attachment to different host species or inert substrates have not been studied. Here organs and tissues involved in the attachment are characterized and their significance in regard to a broader functional and ecological aspect is discussed. Depending on the substrate, the root clusters show different types of failure modes at various frequencies, demonstrating the close interaction between the climber and its substrates. With a Young’s Modulus of 109.2 MPa, the attachment roots are relatively stiff for non-woody roots. The central cylinders of the attachment roots show a high tensile strength of 38 MPa and a very high extensibility of 34%. In host trees naturally co-distributed with English ivy, a ‘balanced’ occurrence of failure of the attachment system of the climber and the bark of the host is found, suggesting a co-evolution of climber and host. Maximum loads of root clusters normalized by the number of roots match those of individually tested attachment roots. In comparison with most subterranean roots the properties and structure of the attachment roots of English ivy show distinct differences. There exist similarities to the properties found for roots of Galium aparine, suggesting a trend in not fully self-supporting plants towards a higher extensibility. PMID:21914660

  9. Cranial kinesis in geckoes: functional implications.

    PubMed

    Herrel, A; Aerts, P; De Vree, F

    2000-05-01

    Although it is generally assumed that cranial kinesis is a plesiomorphic characteristic in squamates, experimental data tend to contradict this hypothesis. In particular, coupled kinesis (i.e. streptostyly and mesokinesis) presumably arose independently in only a limited number of highly specialised groups. In this study, we investigated cranial kinesis in one of the most specialised of these groups: geckoes. On the basis of cineradiographic and electromyographic data, the fast opening and the slow closing/power stroke phases were modelled to elucidate possible functions of the observed kinesis. The results of these analyses show that the retraction of the muzzle unit during crushing is a self-reinforcing system that increases bite force and reduces the joint forces; the active protraction of the kinetic system during jaw opening, in contrast, enhances opening speed through the coupling of the intracranial units. It can be argued that cranial kinesis in geckoes is probably not an adaptive trait as such but, instead, a consequence of the 'Bauplan' of the cranial system in these animals. Presumably as a result of constructional constraints on the size of the jaw musculature and eyes, the supratemporal and postorbital bars were lost, which resulted in enormous mobility in the skull. To counteract the potential negative factors associated with this (decrease in bite force, skull damage), the kinetic system may have become coupled, and thus functional.

  10. Adhesional instabilities and gecko locomotion

    NASA Astrophysics Data System (ADS)

    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.

  11. Design and fabrication of gecko-inspired adhesives.

    PubMed

    Jin, Kejia; Tian, Yu; Erickson, Jeffrey S; Puthoff, Jonathan; Autumn, Kellar; Pesika, Noshir S

    2012-04-03

    Recently, 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 study, we present an easy, scalable method, relying on conventional and unconventional techniques, to incorporate tilt in the fabrication of synthetic polymer-based dry adhesives mimicking the gecko adhesive system, which provides anisotropic adhesion properties. We measured 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. Consistent with the peel zone model, samples with lower tilt angles yielded larger adhesion forces. The tribological properties of the synthetic arrays were highly anisotropic, reminiscent of the frictional adhesion behavior of gecko setal arrays. When a 60° tilt sample was actuated in the gripping direction, a static adhesion strength of ~1.4 N/cm(2) and a static friction strength of ~5.4 N/cm(2) were obtained. In contrast, when the dry adhesive was actuated in the releasing direction, we measured an initial repulsive normal force and negligible friction.

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

    PubMed

    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.

  13. Carbon nanotube based gecko inspired self-cleaning adhesives

    NASA Astrophysics Data System (ADS)

    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.

  14. Activation of the attachment system in adulthood: threat-related primes increase the accessibility of mental representations of attachment figures.

    PubMed

    Mikulincer, Mario; Gillath, Omri; Shaver, Phillip R

    2002-10-01

    Three studies explored the effects of subliminal threat on the activation of representations of attachment figures. This accessibility was measured in a lexical decision task and a Stroop task following threat- or neutral-word primes, and was compared with the accessibility of representations of other close persons, known but not close persons, and unknown persons. Participants also reported on their attachment style. Threat primes led to increased accessibility of representations of attachment figures. This effect was specific to attachment figures and was replicated across tasks and experiments. Attachment anxiety heightened accessibility of representations of attachment figures even in neutral contexts, whereas attachment avoidance inhibited this activation when the threat prime was the word separation. These effects were not, explained by trait anxiety. The discussion focuses on the dynamics of attachment-system activation in adulthood.

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

    PubMed Central

    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

    2015-01-01

    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. PMID:26584513

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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

    2015-11-20

    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.

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

    PubMed

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

    2012-02-07

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Gecko-Inspired, Controlled Adhesion and Its Applications

    NASA Astrophysics Data System (ADS)

    Menguc, Yigit

    This thesis work is primarily concerned with taking inspiration from the principles of gecko-adhesion in order to control the attachment of synthetic structured adhesives. We present gecko-inspired angled elastomer micropillars with flat or round tip endings as compliant pick-and-place micromanipulators. The pillars are 35 mum in diameter, 90 mum tall, and angled at an inclination of 20°. By gently pressing the tip of a pillar to a part, the pillar adheres to it through intermolecular forces. Next, by retracting quickly, the part is picked from a given donor substrate. During transferring, the adhesion between the pillar and the part is high enough to withstand disturbances due to external forces or the weight of the part. During release of the part onto a receiver substrate, the contact area of the pillar to the part is drastically reduced by controlled vertical or shear displacement, which results in reduced adhesive forces. The maximum repeatable ratio of pick-to-release adhesive forces was measured as 39 to 1. We find that a flat tip shape and shear displacement control provide a higher pick-to-release adhesion ratio than a round tip and vertical displacement control, respectively. We present a model of forces to serve as a framework for the operation of this micromanipulator. Finally, demonstrations of pick-and-place manipulation of mum-scale silicon microplatelets and a cm-scale glass cover slip serve as proofs of concept. The compliant polymer micropillars are safe for use with fragile parts, and, due to exploiting intermolecular forces, could be effective on most materials and in air, vacuum, and liquid environments. We present a study of the self-cleaning and contamination resistance phenomena of synthetic gecko-inspired adhesives made from elastomeric polyurethane. The phenomenon of self-cleaning makes the adhesive foot of the gecko robust against dirt, and makes it effectively sticky throughout the lifetime of the material (within the molting cycles

  1. Fiber feed for the CFHT Gecko spectrograph

    NASA Astrophysics Data System (ADS)

    Baudrand, Jacques; Vitry, Rene

    2000-08-01

    Motivated by a strong concern to keep maintenance work as low as possible the direction of the CFHT had for some times contemplated the possibility to replace the original mirror train f/20 focus feeding their Gecko High Resolution Coude Spectrograph by a more convenient fiber link coupled to the f/8 Cassegrain focus. A decision supporting that idea was ultimately taken two years ago and our group at the OPM was contacted to build such a system according to precise specifications. This telescope facility, baptized CAFÉ for Cassegrain Fiber Environment, has now arrived to near completion and we are able to present here its main characteristics and the technical solutions that were adopted to meet the CFHT requirements and to provide the system with the best performances in terms of robustness and efficiency.

  2. Gecko Adhesion on Wet and Dry Patterned Substrates.

    PubMed

    Stark, Alyssa Y; Palecek, Amanda M; Argenbright, Clayton W; Bernard, Craig; Brennan, Anthony B; Niewiarowski, Peter H; Dhinojwala, Ali

    2015-01-01

    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.

  3. Gecko Adhesion on Wet and Dry Patterned Substrates

    PubMed Central

    Stark, Alyssa Y.; Palecek, Amanda M.; Argenbright, Clayton W.; Bernard, Craig; Brennan, Anthony B.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2015-01-01

    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. PMID:26696412

  4. Corrosion of coupled metals in a dental magnetic attachment system.

    PubMed

    Iimuro, F T; Yoneyama, T; Okuno, O

    1993-12-01

    Implants and magnetic attachments are becoming widespread in dental treatment. Their associated use, implants and magnetic attachments, can be seen often too. In those cases, it is difficult to avoid coupling of different metals. The corrosion behavior of the metals is expected to be different depending on whether it is found in an isolated or a coupled condition. Potential corrosion couples in a dental magnetic attachment system among titanium, ferromagnetic stainless steel, gold alloy type IV, and gold-silver-palladium alloy were studied by an immersion test in 1% lactic acid for 7 days and potential/current density curves were measured. Corrosion of titanium and ferromagnetic stainless steel seemed to be accelerated by coupling with gold alloys or gold-silver-palladium alloys. On the other hand, the corrosion amount of gold alloy and gold-silver-palladium alloys were attenuated by coupling.

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

    PubMed

    Stark, Alyssa Y; Wucinich, Nicholas A; Paoloni, Eva L; Niewiarowski, Peter H; Dhinojwala, Ali

    2014-01-01

    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.

  6. Self-Drying: A Gecko's Innate Ability to Remove Water from Wet Toe Pads

    PubMed Central

    Stark, Alyssa Y.; Wucinich, Nicholas A.; Paoloni, Eva L.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2014-01-01

    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. PMID:25054217

  7. Neurological Aspects of the Disorganized/Disoriented Attachment Classification System: Differentiating Quality of the Attachment Relationship from Neurological Impairment.

    ERIC Educational Resources Information Center

    Pipp-Siegel, Sandra; Siegel, Clifford H.; Dean, Janet

    1999-01-01

    Examines possible neurological causes of the various indices of D attachment status. Describes a system of attachment categories and the criteria for assessing disorganized and disoriented behavior, pointing out which of these behaviors may result from neurological abnormalities. Suggests a strategy for differentiating neurological risk status…

  8. Towards gecko-feet-inspired bandages.

    PubMed

    Yanik, Mehmet Fatih

    2009-01-01

    A novel bandage inspired by gecko feet might one day be used during emergencies and internal surgeries. The bandage uses a combination of nanofabricated structures, biodegradable materials and adhesive surface chemistry that allows adhesion onto even wet, moving tissue.

  9. Active Tails Enhance Arboreal Acrobatics in Geckos

    DTIC Science & Technology

    2008-03-18

    SI Movie 6). Discovering that active tails allow arboreal acrobatics in geckos opens the door for future studies of the tail’s neurome- chanical...declare no conflict of interest. This article is a PNAS Direct Submission. Freely available online through the PNAS open access option. *Present...ranging from 2.5 to 8.0 ms1. We mounted transparent Plexiglas sidewalls around the opening of the wind tunnel. This prevented geckos from maneuvering

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

    PubMed

    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.

  11. Active tails enhance arboreal acrobatics in geckos

    PubMed Central

    Jusufi, Ardian; Goldman, Daniel I.; Revzen, Shai; Full, Robert J.

    2008-01-01

    Geckos are nature's elite climbers. Their remarkable climbing feats have been attributed to specialized feet with hairy toes that uncurl and peel in milliseconds. Here, we report that the secret to the gecko's arboreal acrobatics includes an active tail. We examine the tail's role during rapid climbing, aerial descent, and gliding. We show that a gecko's tail functions as an emergency fifth leg to prevent falling during rapid climbing. A response initiated by slipping causes the tail tip to push against the vertical surface, thereby preventing pitch-back of the head and upper body. When pitch-back cannot be prevented, geckos avoid falling by placing their tail in a posture similar to a bicycle's kickstand. Should a gecko fall with its back to the ground, a swing of its tail induces the most rapid, zero-angular momentum air-righting response yet measured. Once righted to a sprawled gliding posture, circular tail movements control yaw and pitch as the gecko descends. Our results suggest that large, active tails can function as effective control appendages. These results have provided biological inspiration for the design of an active tail on a climbing robot, and we anticipate their use in small, unmanned gliding vehicles and multisegment spacecraft. PMID:18347344

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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).

  14. Removable, hermetically-sealing, filter attachment system for hostile environments

    DOEpatents

    Mayfield, Glenn L [Richland, WA

    1983-01-01

    A removable and reusable filter attachment system. A filter medium is fixed o, and surrounded by, a filter frame having a coaxial, longitudinally extending, annular rim. The rim engages an annular groove which surrounds the opening of a filter housing. The annular groove contains a fusible material and a heating mechanism for melting the fusible material. Upon resolidifying, the fusible material forms a hermetic bond with the rim and groove. Remelting allows detachment and replacement of the filter frame.

  15. A microfabricated wedge-shaped adhesive array displaying gecko-like dynamic adhesion, directionality and long lifetime.

    PubMed

    Parness, Aaron; Soto, Daniel; Esparza, Noé; Gravish, Nick; Wilkinson, Matt; Autumn, Kellar; Cutkosky, Mark

    2009-12-06

    Gecko adhesion has become a paradigmatic example of bio-inspired engineering, yet among the many gecko-like synthetic adhesives (GSAs), truly gecko-like performance remains elusive. Many GSAs have previously demonstrated one or two features of the gecko adhesive. We present a new wedge-shaped GSA that exhibits several gecko-like properties simultaneously: directional features; zero force at detachment; high ratio of detachment force to preload force; non-adhesive default state; and the ability to maintain performance while sliding, even after thousands of cycles. Individual wedges independently detach and reattach during sliding, resulting in high levels of shear and normal adhesion during drag. This behaviour provides a non-catastrophic failure mechanism that is desirable for applications such as climbing robots where sudden contact failure would result in serious falls. The effects of scaling patch sizes up to tens of square centimetres are also presented and discussed. Patches of 1 cm(2) had an adhesive pressure of 5.1 kPa while simultaneously supporting 17.0 kPa of shear. After 30 000 attachment/detachment cycles, a patch retained 67 per cent of its initial adhesion and 76 per cent of its initial shear without cleaning. Square-based wedges of 20 mum and 50 mum are manufactured in a moulding process where moulds are fabricated using a dual-side, dual-angle lithography process on quartz wafers with SU-8 photoresist as the mould material and polydimethylsiloxane as the cast material.

  16. Peramorphic traits in the tokay gecko skull.

    PubMed

    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.

  17. Defining the brain systems of lust, romantic attraction, and attachment.

    PubMed

    Fisher, Helen E; Aron, Arthur; Mashek, Debra; Li, Haifang; Brown, Lucy L

    2002-10-01

    Mammals and birds have evolved three primary, discrete, interrelated emotion-motivation systems in the brain for mating, reproduction, and parenting: lust, attraction, and male-female attachment. Each emotion-motivation system is associated with a specific constellation of neural correlates and a distinct behavioral repertoire. Lust evolved to initiate the mating process with any appropriate partner; attraction evolved to enable individuals to choose among and prefer specific mating partners, thereby conserving their mating time and energy; male-female attachment evolved to enable individuals to cooperate with a reproductive mate until species-specific parental duties have been completed. The evolution of these three emotion-motivation systems contribute to contemporary patterns of marriage, adultery, divorce, remarriage, stalking, homicide and other crimes of passion, and clinical depression due to romantic rejection. This article defines these three emotion-motivation systems. Then it discusses an ongoing project using functional magnetic resonance imaging of the brain to investigate the neural circuits associated with one of these emotion-motivation systems, romantic attraction.

  18. Superhydrophobicity of the gecko toe pad: biological optimization versus laboratory maximization.

    PubMed

    Stark, Alyssa Y; Subarajan, Shairani; Jain, Dharamdeep; Niewiarowski, Peter H; Dhinojwala, Ali

    2016-08-06

    While many gecko-inspired hierarchically structured surfaces perform as well as or better than the natural adhesive system, these designs often fail to function across a variety of contexts. For example, the gecko can adhere to rough, wet and dirty surfaces; however, most synthetic mimics cannot maintain function when faced with a similar situation. The solution to this problem lies in a more thorough investigation of the natural system. Here, we review the adhesive system of the gecko toe pad, as well as the far less-well-studied anti-adhesive system that results from the chemistry and structure of the toe pad (superhydrophobicity). This paradoxical relationship serves as motivation to study functional optimization at the system level. As an example, we experimentally investigate the role of surface lipids in adhesion and anti-adhesion, and find a clear performance trade-off related to shear adhesion in air on a hydrophilic surface. This represents the first direct investigation of the role of surface lipids in gecko adhesion and anti-adhesion, and supports the argument that a system-level approach is necessary to elucidate optimization in biological systems. Without such an approach, bioinspired designs will be limited in functionality and context, especially compared to the natural systems they mimic.This article is part of the themed issue 'Bioinspired hierarchically structured surfaces for green science'.

  19. Preferential attachment and growth dynamics in complex systems

    NASA Astrophysics Data System (ADS)

    Yamasaki, Kazuko; Matia, Kaushik; Buldyrev, Sergey V.; Fu, Dongfeng; Pammolli, Fabio; Riccaboni, Massimo; Stanley, H. Eugene

    2006-09-01

    Complex systems can be characterized by classes of equivalency of their elements defined according to system specific rules. We propose a generalized preferential attachment model to describe the class size distribution. The model postulates preferential growth of the existing classes and the steady influx of new classes. According to the model, the distribution changes from a pure exponential form for zero influx of new classes to a power law with an exponential cut-off form when the influx of new classes is substantial. Predictions of the model are tested through the analysis of a unique industrial database, which covers both elementary units (products) and classes (markets, firms) in a given industry (pharmaceuticals), covering the entire size distribution. The model’s predictions are in good agreement with the data. The paper sheds light on the emergence of the exponent τ≈2 observed as a universal feature of many biological, social and economic problems.

  20. NMR spectroscopy reveals the presence and association of lipids and keratin in adhesive gecko setae

    PubMed Central

    Jain, Dharamdeep; Stark, Alyssa Y.; Niewiarowski, Peter H.; Miyoshi, Toshikazu; Dhinojwala, Ali

    2015-01-01

    Lipid and protein aggregates are one of the fundamental materials of biological systems. Examples include cell membranes, insect cuticle, vertebrate epidermis, feathers, hair and adhesive structures known as ‘setae’ on gecko toes. Until recently gecko setae were assumed to be composed entirely of keratin, but analysis of footprints left behind by geckos walking on surfaces revealed that setae include various kinds of lipids. However, the arrangement and molecular-level behavior of lipids and keratin in the setae is still not known. In the present study we demonstrate, for the first time, the use of Nuclear Magnetic Resonance (NMR) spectroscopy techniques to confirm the presence of lipids and investigate their association with keratin in ‘pristine' sheds, or natural molts of the adhesive toe pad and non-adhesive regions of the skin. Analysis was also carried on the sheds after they were ‘delipidized’ to remove surface lipids. Our results show a distribution of similar lipids in both the skin and toe shed but with different dynamics at a molecular level. The present study can help us understand the gecko system both biologically and for design of synthetic adhesives, but the findings may be relevant to the characteristics of lipid-protein interactions in other biological systems. PMID:25902194

  1. Use of the adult attachment projective picture system in psychodynamic psychotherapy with a severely traumatized patient

    PubMed Central

    George, Carol; Buchheim, Anna

    2014-01-01

    The following case study is presented to facilitate an understanding of how the attachment information evident from Adult Attachment Projective Picture System (AAP) assessment can be integrated into a psychodynamic perspective in making therapeutic recommendations that integrate an attachment perspective. The Adult Attachment Projective Picture System (AAP) is a valid representational measure of internal representations of attachment based on the analysis of a set of free response picture stimuli designed to systematically activate the attachment system (George and West, 2012). The AAP provides a fruitful diagnostic tool for psychodynamic-oriented clinicians to identify attachment-based deficits and resources for an individual patient in therapy. This paper considers the use of the AAP with a traumatized patient in an inpatient setting and uses a case study to illustrate the components of the AAP that are particularly relevant to a psychodynamic conceptualization. The paper discusses also attachment-based recommendations for intervention. PMID:25140164

  2. THE NATURE OF THE GECKO VISUAL PIGMENT

    PubMed Central

    Crescitelli, Frederick

    1956-01-01

    Retinal extracts of the Australian gecko, Phyllurus milii (White), have revealed the presence of a photosensitive pigment, unusual for terrestrial animals, because of its absorption maximum at 524 mµ. This pigment has an absorption spectrum which is identical in form with that of other visual chromoproteins. It is not a porphyropsin, for bleaching revealed the presence, not of retinene2, but of retinene1 as a chromophore. Photolabile pigments with characteristics similar to those of the Phyllurus visual pigment were also detected in retinal extracts of six other species of nocturnal geckos. The presence of this retinal chromoprotein adequately accounts for the unusual visual sensitivity curve described by Denton for the nocturnal gecko. This pigment may have special biological significance in terms of the unique phylogenetic position of geckos as living representatives of nocturnal animals which retain some of the characteristics of their diurnal ancestors. The occurrence of this retinene1 pigment, intermediate in spectral position between rhodopsin and iodopsin, is interpreted in support of the transmutation theory of Walls. The results and interpretation of this investigation point up the fact that, from a phylogenetic point of view, too great an emphasis on the duplicity theory may serve to detract attention from the evolutionary history of the retina and the essential unitarianism of the visual cells. PMID:13385449

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

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Technical Reports Server (NTRS)

    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

  5. Type Three Secretion System in Attaching and Effacing Pathogens.

    PubMed

    Gaytán, Meztlli O; Martínez-Santos, Verónica I; Soto, Eduardo; González-Pedrajo, Bertha

    2016-01-01

    Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens.

  6. Type Three Secretion System in Attaching and Effacing Pathogens

    PubMed Central

    Gaytán, Meztlli O.; Martínez-Santos, Verónica I.; Soto, Eduardo; González-Pedrajo, Bertha

    2016-01-01

    Enteropathogenic Escherichia coli and enterohemorrhagic E. coli are diarrheagenic bacterial human pathogens that cause severe gastroenteritis. These enteric pathotypes, together with the mouse pathogen Citrobacter rodentium, belong to the family of attaching and effacing pathogens that form a distinctive histological lesion in the intestinal epithelium. The virulence of these bacteria depends on a type III secretion system (T3SS), which mediates the translocation of effector proteins from the bacterial cytosol into the infected cells. The core architecture of the T3SS consists of a multi-ring basal body embedded in the bacterial membranes, a periplasmic inner rod, a transmembrane export apparatus in the inner membrane, and cytosolic components including an ATPase complex and the C-ring. In addition, two distinct hollow appendages are assembled on the extracellular face of the basal body creating a channel for protein secretion: an approximately 23 nm needle, and a filament that extends up to 600 nm. This filamentous structure allows these pathogens to get through the host cells mucus barrier. Upon contact with the target cell, a translocation pore is assembled in the host membrane through which the effector proteins are injected. Assembly of the T3SS is strictly regulated to ensure proper timing of substrate secretion. The different type III substrates coexist in the bacterial cytoplasm, and their hierarchical secretion is determined by specialized chaperones in coordination with two molecular switches and the so-called sorting platform. In this review, we present recent advances in the understanding of the T3SS in attaching and effacing pathogens. PMID:27818950

  7. The Systemic Interaction of Attachment on Psychophysiological Arousal in Couple Conflict.

    PubMed

    Taylor, Nathan C; Seedall, Ryan B; Robinson, W David; Bradford, Kay

    2017-05-15

    Attachment in adult romantic relationships has long been linked to conflict styles. Psychophysiological measures have provided additional insight into this association by accessing less conscious and controlled responses to conflict. The aim of this study was to explore the relationship between attachment anxiety, attachment avoidance, and the interaction between attachment styles on skin conductance responses during conflict and recovery from conflict. Using dyadic analysis of 50 heterosexual couples, we found evidence of a systemic effect of attachment, where psychophysiological arousal increased when one partner had higher levels of attachment anxiety and the other partner had higher levels of attachment avoidance. Attachment avoidance was also negatively associated with increased levels of arousal. Relationship and clinical implications of these findings are discussed. © 2017 American Association for Marriage and Family Therapy.

  8. Simulation of synthetic gecko arrays shearing on rough surfaces

    PubMed Central

    Gillies, Andrew G.; Fearing, Ronald S.

    2014-01-01

    To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson–Kendall–Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features. PMID:24694893

  9. Simulation of synthetic gecko arrays shearing on rough surfaces.

    PubMed

    Gillies, Andrew G; Fearing, Ronald S

    2014-06-06

    To better understand the role of surface roughness and tip geometry in the adhesion of gecko synthetic adhesives, a model is developed that attempts to uncover the relationship between surface feature size and the adhesive terminal feature shape. This model is the first to predict the adhesive behaviour of a plurality of hairs acting in shear on simulated rough surfaces using analytically derived contact models. The models showed that the nanoscale geometry of the tip shape alters the macroscale adhesion of the array of fibres by nearly an order of magnitude, and that on sinusoidal surfaces with amplitudes much larger than the nanoscale features, spatula-shaped features can increase adhesive forces by 2.5 times on smooth surfaces and 10 times on rough surfaces. Interestingly, the summation of the fibres acting in concert shows behaviour much more complex that what could be predicted with the pull-off model of a single fibre. Both the Johnson-Kendall-Roberts and Kendall peel models can explain the experimentally observed frictional adhesion effect previously described in the literature. Similar to experimental results recently reported on the macroscale features of the gecko adhesive system, adhesion drops dramatically when surface roughness exceeds the size and spacing of the adhesive fibrillar features.

  10. How habitat disturbance benefits geckos: Conservation implications.

    PubMed

    Ineich, Ivan

    2010-01-01

    I here provide some field observations and literature data showing that egg laying site availability could be the main limiting factor for most arboreal gecko population dynamics. Several natural (typhoons, volcanism, sea level variations) or human-mediated habitat modifications (garden openings in forested areas) provide enough habitat disturbances to significantly increase reproductive outputs in island gecko populations. Such observations, however, also apply to continental populations. Our observations suggest that artificial shelter and egg laying site creation could easily allow populations to increase and also supply easier access to arboreal species for ecological or biodiversity studies. Furthermore, our observations also point out that occurrence in man-made habitats and genetic uniformity of most widespread island lizards should not be considered as evidence of their recent introduction through human agency. Copyright 2009 Académie des sciences. Published by Elsevier SAS. All rights reserved.

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

    PubMed

    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.

  12. Retention force and fatigue strength of overdenture attachment systems.

    PubMed

    Botega, D M; Mesquita, M F; Henriques, G E P; Vaz, L G

    2004-09-01

    This study evaluated retention force and fatigue resistance of two overdenture attachment systems. Twenty samples (O-ring and Bar-Clip) from two manufacturers (Conexão Sistemas de Prótese and Lifecore Biomedical) were prepared and divided into four groups: (i) Conexão/O-ring; (ii) Conexão/Bar-Clip; (iii) Lifecore/O-ring and (iv) Lifecore/Bar-Clip, with five samples in each group. They were submitted to mechanical fatigue test using a servohydraulic machine performing 5500 cycles of insertion and removal (f=0.8 Hz), immersed in artificial saliva. Retention force values were obtained three times (0, 3000 and after 5500 cycles) simulating the clinical service, using a tensile strength at 1 mm min(-1) and load cell of 1 kN. Data were analysed with analysis of variance and Tukey's test at 5% level. Results showed that Conexão/Bar-Clip specimens had significantly higher retention values than Lifecore/Bar-Clip (44.61 and 18.44 N, respectively), Conexão/O-ring specimens had significantly lower values than Lifecore/O-ring (13.91 and 19.75 N, respectively). Conexão/Bar-Clip values were always significantly higher than those of Conexão/O-ring group (44.61 and 13.91 N, respectively). Lifecore (O-ring and Bar-Clip) presented similar values (19.75 and 18.44 N, respectively). The systems evaluated showed satisfactory retention force values, before and after fatigue testing. Conexão/Bar-Clip specimens presented the highest values. A 5-year simulation of insertion and removal did not decrease retention values or fracture components.

  13. Surface wettability plays a significant role in gecko adhesion underwater

    PubMed Central

    Stark, Alyssa Y.; Badge, Ila; Wucinich, Nicholas A.; Sullivan, Timothy W.; Niewiarowski, Peter H.; Dhinojwala, Ali

    2013-01-01

    Although we now have thousands of studies focused on the nano-, micro-, and whole-animal mechanics of gecko adhesion on clean, dry substrates, we know relatively little about the effects of water on gecko adhesion. For many gecko species, however, rainfall frequently wets the natural surfaces they navigate. In an effort to begin closing this gap, we tested the adhesion of geckos on submerged substrates that vary in their wettability. When tested on a wet hydrophilic surface, geckos produced a significantly lower shear adhesive force (5.4 ± 1.33 N) compared with a dry hydrophilic surface (17.1 ± 3.93 N). In tests on an intermediate wetting surface and a hydrophobic surface, we found no difference in shear adhesion between dry and wet contact. Finally, in tests on polytetrafluoroethylene (PTFE), we found that geckos clung significantly better to wet PTFE (8.0 ± 1.09 N) than dry PTFE (1.6 ± 0.66 N). To help explain our results, we developed models based on thermodynamic theory of adhesion for contacting surfaces in different media and found that we can predict the ratio of shear adhesion in water to that in air. Our findings provide insight into how geckos may function in wet environments and also have significant implications for the development of a synthetic gecko mimic that retains adhesion in water. PMID:23576727

  14. Surface wettability plays a significant role in gecko adhesion underwater.

    PubMed

    Stark, Alyssa Y; Badge, Ila; Wucinich, Nicholas A; Sullivan, Timothy W; Niewiarowski, Peter H; Dhinojwala, Ali

    2013-04-16

    Although we now have thousands of studies focused on the nano-, micro-, and whole-animal mechanics of gecko adhesion on clean, dry substrates, we know relatively little about the effects of water on gecko adhesion. For many gecko species, however, rainfall frequently wets the natural surfaces they navigate. In an effort to begin closing this gap, we tested the adhesion of geckos on submerged substrates that vary in their wettability. When tested on a wet hydrophilic surface, geckos produced a significantly lower shear adhesive force (5.4 ± 1.33 N) compared with a dry hydrophilic surface (17.1 ± 3.93 N). In tests on an intermediate wetting surface and a hydrophobic surface, we found no difference in shear adhesion between dry and wet contact. Finally, in tests on polytetrafluoroethylene (PTFE), we found that geckos clung significantly better to wet PTFE (8.0 ± 1.09 N) than dry PTFE (1.6 ± 0.66 N). To help explain our results, we developed models based on thermodynamic theory of adhesion for contacting surfaces in different media and found that we can predict the ratio of shear adhesion in water to that in air. Our findings provide insight into how geckos may function in wet environments and also have significant implications for the development of a synthetic gecko mimic that retains adhesion in water.

  15. Sliding Adhesion Dynamics of Isolated Gecko Setal Arrays

    NASA Astrophysics Data System (ADS)

    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.

  16. Coming to America: Multiple Origins of New World Geckos

    PubMed Central

    Gamble, Tony; Bauer, Aaron M; Colli, Guarino R; Greenbaum, Eli; Jackman, Todd R; Vitt, Laurie J; Simons, Andrew M

    2010-01-01

    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 biogeographic scenario for the New World geckos. Patterns of New World gecko origins are consistent with almost every biogeographic 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. PMID:21126276

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

    PubMed

    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.

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

    PubMed

    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. Optical gecko toe: Optically controlled attractive near-field forces between plasmonic metamaterials and dielectric or metal surfaces

    NASA Astrophysics Data System (ADS)

    Zhang, J.; MacDonald, K. F.; Zheludev, N. I.

    2012-05-01

    On the mesoscopic scale, electromagnetic forces are of fundamental importance to an enormously diverse range of systems, from optical tweezers to the adhesion of gecko toes. Here we show that a strong light-driven force may be generated when a plasmonic metamaterial is illuminated in close proximity to a dielectric or metal surface. This near-field force can exceed radiation pressure and Casimir forces to provide an optically controlled adhesion mechanism mimicking the gecko toe: At illumination intensities of just a few tens of nW/μm2 it is sufficient to overcome the Earth's gravitational pull.

  20. Attached manipulator system design and concept verification for zero-g simulation

    NASA Technical Reports Server (NTRS)

    Booker, R.; Burkitt, W.; Corveleyn, P.; Cramer, P.; Duwaik, O.; Flatau, C.; Garber, P.; Grant, C.; Greeb, F.; Johnson, C.

    1973-01-01

    The attached manipulator system (AMS) is to simulate and demonstrate zero-g shuttle manipulator cargo handling operations. It is not the design or development of the shuttle attached manipulator system (SAMS); however, every effort is being made, to insure that the AMS will be functionally similar to the SAMS.

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

    PubMed Central

    Lenzi, Delia; Trentini, Cristina; Tambelli, Renata; Pantano, Patrizia

    2015-01-01

    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. PMID:26379578

  2. Assessment of the GECKO-A Modeling Tool and Simplified 3D Model Parameterizations for SOA Formation

    NASA Astrophysics Data System (ADS)

    Aumont, B.; Hodzic, A.; La, S.; Camredon, M.; Lannuque, V.; Lee-Taylor, J. M.; Madronich, S.

    2014-12-01

    Explicit chemical mechanisms aim to embody the current knowledge of the transformations occurring in the atmosphere during the oxidation of organic matter. These explicit mechanisms are therefore useful tools to explore the fate of organic matter during its tropospheric oxidation and examine how these chemical processes shape the composition and properties of the gaseous and the condensed phases. Furthermore, explicit mechanisms provide powerful benchmarks to design and assess simplified parameterizations to be included 3D model. Nevertheless, the explicit mechanism describing the oxidation of hydrocarbons with backbones larger than few carbon atoms involves millions of secondary organic compounds, far exceeding the size of chemical mechanisms that can be written manually. Data processing tools can however be designed to overcome these difficulties and automatically generate consistent and comprehensive chemical mechanisms on a systematic basis. The Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) has been developed for the automatic writing of explicit chemical schemes of organic species and their partitioning between the gas and condensed phases. GECKO-A can be viewed as an expert system that mimics the steps by which chemists might develop chemical schemes. GECKO-A generates chemical schemes according to a prescribed protocol assigning reaction pathways and kinetics data on the basis of experimental data and structure-activity relationships. In its current version, GECKO-A can generate the full atmospheric oxidation scheme for most linear, branched and cyclic precursors, including alkanes and alkenes up to C25. Assessments of the GECKO-A modeling tool based on chamber SOA observations will be presented. GECKO-A was recently used to design a parameterization for SOA formation based on a Volatility Basis Set (VBS) approach. First results will be presented.

  3. Attachment and detachment processes as a typological index of relational systems.

    PubMed

    De Pascale, A; Gaetano, P; Gentili, N; Vella, G

    1992-01-01

    Attachment and detachment processes, as defined by modern attachment theories, place them as integrative between innate and acquired behaviors, like a regulatory system for every close relationship. As a consequence, family attachment styles, which proceed-throughout development-together with personal identity construction processes, stress the notion of relationship as a dialectical and interactive process, defining the irreducible duality of human experience, in which the personal individuality construction is linked, since the earliest phases of life, to the significant relationships. Dysfunctional patterns of attachment and detachment and self-construction processes interact in defining personal organizations one can observe in psychopathological situations; some clinical examples are proposed.

  4. Shunt attachment and method for interfacing current collection systems

    DOEpatents

    Denney, P.E.; Iyer, N.C.; Hannan, W.F. III.

    1992-12-08

    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. 6 figs.

  5. Shunt attachment and method for interfacing current collection systems

    DOEpatents

    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.

  6. Pin and roller attachment system for ceramic blades

    DOEpatents

    Shaffer, James E.

    1995-01-01

    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.

  7. Pin and roller attachment system for ceramic blades

    DOEpatents

    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.

  8. Performance Modeling of Network-Attached Storage Device Based Hierarchical Mass Storage Systems

    NASA Technical Reports Server (NTRS)

    Menasce, Daniel A.; Pentakalos, Odysseas I.

    1995-01-01

    Network attached storage devices improve I/O performance by separating control and data paths and eliminating host intervention during the data transfer phase. Devices are attached to both a high speed network for data transfer and to a slower network for control messages. Hierarchical mass storage systems use disks to cache the most recently used files and a combination of robotic and manually mounted tapes to store the bulk of the files in the file system. This paper shows how queuing network models can be used to assess the performance of hierarchical mass storage systems that use network attached storage devices as opposed to host attached storage devices. Simulation was used to validate the model. The analytic model presented here can be used, among other things, to evaluate the protocols involved in 1/0 over network attached devices.

  9. Authentication of Chinese crude drug gecko by DNA barcoding.

    PubMed

    Gu, Hai-Feng; Xia, Yun; Penga, Rui; Mo, Bang-Hui; Li, Li; Zenga, Xiao-Mao

    2011-01-01

    Gekko gecko, an animal used as a valued traditional Chinese medicine, has been widely used for over 2000 years. Due to localized habitat destruction, the amount of G. gecko has dramatically decreased in recent years. As a result, more and more adulterants have been detected in the traditional medicine, which has resulted in a chaotic market. Therefore, a correct identification method is badly needed. In this study, we employed a new molecular method of DNA barcoding for discriminating gecko from its adulterants. Fifty-seven specimens of gecko and its adulterants were collected as test samples. The full-barcode and mini-barcode sequences of these specimens were separately amplified and sequenced separately. Together with other published barcode sequences, we detected that the intra-specific sequence diversity was far lower than the inter-specific diversity in G. gecko and its adulterants (3% compared with 35% in full-length barcode; 4% compared with 33.5% in mini-barcode). These results showed that both the full-length and mini-barcodes were effective for identifying gecko, which suggested that the DNA barcode could be an effective and powerful tool for identifying the Chinese crude drug gecko.

  10. Role of contact electrification and electrostatic interactions in gecko adhesion.

    PubMed

    Izadi, Hadi; Stewart, Katherine M E; Penlidis, Alexander

    2014-09-06

    Geckos, which are capable of walking on walls and hanging from ceilings with the help of micro-/nano-scale hierarchical fibrils (setae) on their toe pads, have become the main prototype in the design and fabrication of fibrillar dry adhesives. As the unique fibrillar feature of the toe pads of geckos allows them to develop an intimate contact with the substrate the animal is walking on or clinging to, it is expected that the toe setae exchange significant numbers of electric charges with the contacted substrate via the contact electrification (CE) phenomenon. Even so, the possibility of the occurrence of CE and the contribution of the resulting electrostatic interactions to the dry adhesion of geckos have been overlooked for several decades. In this study, by measuring the magnitude of the electric charges, together with the adhesion forces, that gecko foot pads develop in contact with different materials, we have clarified for the first time that CE does contribute effectively to gecko adhesion. More importantly, we have demonstrated that it is the CE-driven electrostatic interactions which dictate the strength of gecko adhesion, and not the van der Waals or capillary forces which are conventionally considered as the main source of gecko adhesion.

  11. The optokinetic reaction in foveate and afoveate geckos.

    PubMed

    Masseck, Olivia; Röll, Beate; Hoffmann, Klaus-Peter

    2008-03-01

    To investigate determinants of symmetry of the monocular horizontal optokinetic reaction (hOKR) in vertebrates, we performed behavioural studies in diurnal foveate, as well as nocturnal afoveate geckos. During binocular viewing hOKR gain was equal for movement to the left or right, during monocular stimulation, all afoveate geckos (Lepidodactylus lugubris, Gekko gecko, Eublepharis macularius) and the foveate Lygodactylus spp. exclusively reacted to temporo-nasal stimulation with stabilising head movements whereas in Phelsuma madagascariensis a naso-temporal component of hOKR could be elicited albeit much weaker. Thus, neither the presence of a fovea nor lifestyle seems to be decisive for a symmetrical monocular hOKR.

  12. Finding approximate gene clusters with Gecko 3

    PubMed Central

    Winter, Sascha; Jahn, Katharina; Wehner, Stefanie; Kuchenbecker, Leon; Marz, Manja; Stoye, Jens; Böcker, Sebastian

    2016-01-01

    Gene-order-based comparison of multiple genomes provides signals for functional analysis of genes and the evolutionary process of genome organization. Gene clusters are regions of co-localized genes on genomes of different species. The rapid increase in sequenced genomes necessitates bioinformatics tools for finding gene clusters in hundreds of genomes. Existing tools are often restricted to few (in many cases, only two) genomes, and often make restrictive assumptions such as short perfect conservation, conserved gene order or monophyletic gene clusters. We present Gecko 3, an open-source software for finding gene clusters in hundreds of bacterial genomes, that comes with an easy-to-use graphical user interface. The underlying gene cluster model is intuitive, can cope with low degrees of conservation as well as misannotations and is complemented by a sound statistical evaluation. To evaluate the biological benefit of Gecko 3 and to exemplify our method, we search for gene clusters in a dataset of 678 bacterial genomes using Synechocystis sp. PCC 6803 as a reference. We confirm detected gene clusters reviewing the literature and comparing them to a database of operons; we detect two novel clusters, which were confirmed by publicly available experimental RNA-Seq data. The computational analysis is carried out on a laptop computer in <40 min. PMID:27679480

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

    PubMed Central

    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

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

    PubMed

    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.

  15. Light level impacts locomotor biomechanics in a secondarily diurnal gecko, Rhoptropus afer.

    PubMed

    Birn-Jeffery, Aleksandra V; Higham, Timothy E

    2016-11-15

    Locomotion through complex habitats relies on the continuous feedback from a number of sensory systems, including vision. Animals face a visual trade-off between acuity and light sensitivity that depends on light levels, which will dramatically impact the ability to process information and move quickly through a habitat, making ambient illumination an incredibly important ecological factor. Despite this, there is a paucity of data examining ambient light in the context of locomotor dynamics. There have been several independent transitions from the nocturnal ancestor to a diurnal activity pattern among geckos. We examined how ambient light level impacted the locomotor performance and high-speed three-dimensional kinematics of a secondarily diurnal, and cursorial, gecko (Rhoptropus afer) from Namibia. This species is active under foggy and sunny conditions, indicating that a range of ambient light conditions is experienced naturally. Locomotor speed was lowest in the 'no-light' condition compared with all other light intensities, occurring via a combination of shorter stride length and lower stride frequency. Additionally, the centre of mass was significantly lower, and the geckos were more sprawled, in the no-light condition relative to all of the higher light intensities. Locomotor behaviour is clearly sub-optimal under lower light conditions, suggesting that ecological conditions, such as very dense fog, might preclude the ability to run quickly during predator-prey interactions. The impact of ambient light on fitness should be explored further, especially in those groups that exhibit multiple transitions between diel activity patterns.

  16. Evidence for self-cleaning in gecko setae

    PubMed Central

    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. PMID:15630086

  17. Evidence for self-cleaning in gecko setae

    NASA Astrophysics Data System (ADS)

    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

  18. Biomaterial aspects: A key factor in the longevity of implant overdenture attachment systems.

    PubMed

    Daou, Elie E

    2015-01-01

    New attachment systems are released for mandibular two-implant overdentures often without evidence-based support. Biomaterial aspects are now the parameters considered when choosing the appropriate attachment. Studies regarding their properties remain scarce. The purpose of this review was to help the clinician in selrcting the most adapted stud attachments according evidence-based dentistry. An electronic search was conducted using specific databases (PubMed, Medline, and Elsevier libraries). Peer-reviewed articles published in English up to July 2014 were identified. Emphasis was given on the biomaterial aspects and technical complications. No hand search was added. The electronic search generated 115 full-text papers, of which 84 papers were included in the review. The majority were clinical and in vitro studies. Some review articles were also considered. Papers reported survival and failures of overdenture connection systems. Emphasis was laid on attachment deformation. Implant overdentures long-term follow-up studies may provide useful guidelines for the clinician in selecting the type of attachment system and overdenture design. Locator attachments are more and more used, with lesser complications reported.

  19. Involvement of gecko SNAP25b in spinal cord regeneration by promoting outgrowth and elongation of neurites.

    PubMed

    Wang, Yingjie; Dong, Yingying; Song, Honghua; Liu, Yan; Liu, Mei; Yuan, Ying; Ding, Fei; Gu, Xiaosong; Wang, Yongjun

    2012-12-01

    SNARE complex mediates cellular membrane fusion events essential for neurotransmitter release and synaptogenesis. SNAP25, a member of the SNARE proteins, plays critical roles during the development of the central nervous system via regulation by alternative splicing and protein kinase phosphorylation. To date, little information is available regarding the protein in the spinal cord regeneration, especially for the postnatal highly expressed isoform SNAP25b. In the present study, we characterized gecko SNAP25b, which shared high identity with those of other vertebrates. Expression of gecko SNAP25b was temporally upregulated in both neurons of spinal cord and forming ependymal tube following tail amputation, coinciding with the occurrence of regenerate re-innervation. Overexpression of gecko wild type SNAP25b in the SH-SY5Y and undifferentiated PC12 cells promoted the elongation and outgrowth of neurites, while mutant constructs at Serine(187) resulted in differential effects for which S187A had a promoting role. Knockdown of endogenous SNAP25b affected the formation of neurites, which could be rescued by overexpression of SNAP25b. FM1-43 staining revealed that transfection of S187E mutant construct reduced the recruitment of vesicles. In addition, transfection of gecko SNAP25b in the astrocyte, which is absent from neuronal specific VAMP2, was capable of enhancing process elongation, indicating a potential for various alternative protein combinations. Taken together, our data suggest that gecko SNAP25b is involved in spinal cord regeneration by promoting outgrowth and elongation of neurites in a more extensive protein binding manner.

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

    PubMed

    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.

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

    PubMed Central

    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

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

    PubMed

    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.

  3. Equilibria and vibration of a buckled beam with attached masses or spring-mass systems

    NASA Astrophysics Data System (ADS)

    Plaut, Raymond H.; Virgin, Lawrence N.

    2016-09-01

    A buckled beam with immovable pinned ends is considered. Attached to the beam are either one concentrated mass, two concentrated masses, a spring-mass system (that could model a human, robot, or passive vibration absorber), or a horizontal rigid bar with two vertical end springs (a "bounce-pitch" system that could model an animal or a vehicle). In the theoretical analysis, the beam is modeled as an inextensible elastica. Equilibrium configurations are determined first. Then small free vibrations about equilibrium are examined, and the lowest frequencies and corresponding modes are computed. The effects of various parameters are investigated, such as the ratio of the span to the total arc length of the beam, the locations and weights of the attached masses and systems, and the stiffnesses of the springs. For the case of a single attached mass, experiments are conducted and the results are compared to the theoretical ones.

  4. 22 CFR 121.8 - End-items, components, accessories, attachments, parts, firmware, software and systems.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ..., parts, firmware, software and systems. 121.8 Section 121.8 Foreign Relations DEPARTMENT OF STATE...-items, components, accessories, attachments, parts, firmware, software and systems. (a) An end-item is.... Firmware includes but is not limited to circuits into which software has been programmed. (f)...

  5. 22 CFR 121.8 - End-items, components, accessories, attachments, parts, firmware, software and systems.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ..., parts, firmware, software and systems. 121.8 Section 121.8 Foreign Relations DEPARTMENT OF STATE...-items, components, accessories, attachments, parts, firmware, software and systems. (a) An end-item is.... Firmware includes but is not limited to circuits into which software has been programmed. (f)...

  6. Magnetic Flux Density of Different Types of New Generation Magnetic Attachment Systems.

    PubMed

    Akin, Hakan

    2015-07-01

    The purpose of this study was to analyze the static magnetic flux density of different types of new generation laser-welded magnetic attachments in the single position and the attractive position and to determine the effect of different corrosive environments on magnetic flux density. Magnetic flux densities of four magnetic attachment systems (Hyper slim, Hicorex slim, Dyna, and Steco) were measured with a gaussmeter. Then magnetic attachment systems were immersed in two different media, namely 1% lactic acid solution (pH 2.3), and 0.9% NaCl solution (pH 7.3). Magnetic flux densities of the attachment systems were measured with a gaussmeter after immersion to compare with measurements before immersion (α = 0.05). The data were statistically evaluated with one-way ANOVA, paired-samples t-test, and post hoc Tukey-Kramer multiple comparisons tests (α = 0.05). The highest magnetic flux density was found in Dyna magnets for both single and attractive positions. In addition, after the magnets were in the corrosive environments for 2 weeks, they had a significant decrease in magnetic flux density (p < 0.05). No significant differences were found between corrosive environments (p > 0.05). The leakage flux of all the magnetic attachments did not exceed the WHO's guideline of 40 mT. The magnets exhibited a significant decrease in magnetic flux density after aging in corrosive environments including lactic acid and NaCl. © 2014 by the American College of Prosthodontists.

  7. Effects of surface wettability on gecko adhesion underwater.

    PubMed

    Peng, Z L; Wang, C; Chen, S H

    2014-10-01

    Recent experiments have shown that gecko adhesion underwater depends significantly on surface wettability. Theoretical models of a gecko seta adhering on different substrates are firstly established in order to disclose such an adhesion mechanism. The results show that the capillary force induced by nano-bubbles between gecko seta and the substrate is the mainly influencing factor. The capillary force exhibits an attractive feature between gecko setae and hydrophobic surfaces underwater. However, it is extremely weak or even repulsive on hydrophilic surfaces underwater. A self-similarly splitting model is further considered to simulate multiple gecko setae on substrates underwater. It is interesting to find that the total capillary force depends significantly on the number of nano-bubble bridges and wettability of substrates. The total force is attractive and increases monotonically with the increase of the splitting number on hydrophobic substrates underwater. However, it decreases drastically or even becomes repulsive on hydrophilic substrates underwater. The present result can not only give a reasonable explanation on the existing experimental observations but also be helpful for the design of novel biomimetic adhesives.

  8. System Development Report for Automated Polymer Die Attach Machine.

    DTIC Science & Technology

    1981-12-18

    components are shown in Figure 2. A helical tooth rack and pinion driven by a similar antibacklash gear train and d.c. servo motor move the arm in the...If the system.halts because of fail - ure to place a die, it will be capable of being reset to capture the missed operation without addi- tional data...mechanism consists of a flanged base that contains a servo motor, precision zero backlash gear box and position encoder to control the 0 or rotational axes

  9. Coculture system that mimics in vivo attachment processes in bovine trophoblast cells.

    PubMed

    Sakurai, Toshihiro; Bai, Hanako; Bai, Rulan; Arai, Miki; Iwazawa, Makoto; Zhang, Jinfeng; Konno, Toshihiro; Godkin, James D; Okuda, Kiyoshi; Imakawa, Kazuhiko

    2012-09-01

    The establishment of pregnancy requires bidirectional communication between the developing conceptus and the uterine endometrium. The aim of this study was to establish an in vitro coculture system with bovine trophoblast cells and uterine epithelial cells (EECs) that mimics the in vivo attachment process. We previously reported that expression of interferon tau (IFNT), a major secretory product from the trophectoderm, decreases with changes in chromatin structure when the conceptus successfully attaches to the uterine epithelium. Thus, IFNT is a good marker to assess whether attachment has successfully occurred. In this study, bovine trophoblast CT-1 cells were cultured to generate spheroids, which were then placed on type I collagen-coated plates (monoculture) or bovine EECs (coculture) with or without uterine flushings collected from Day 15 cyclic or Days 15, 17, or 19 pregnant animals. In the coculture but not the monoculture, addition of uterine flushings from Day 15 or 17 pregnant animals resulted in decreased IFNT and CDX2 mRNA expression in CT-1 spheroids, accompanied with changes in histone modifications. In monocultured CT-1 spheroids, integrin subunit ITGA8 and ITGB3 mRNAs were minimally expressed but were induced in cocultured CT-1 spheroids with or without uterine flushings. Expression of CDH2, another marker for bovine conceptus attachment to the uterine epithelium, was also induced in the cocultured CT-1 spheroids. These results suggest that this in vitro coculture system could be used to isolate processes essential for conceptus attachment to uterine EECs.

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

    PubMed

    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.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:24785293

  13. Neural Response during the Activation of the Attachment System in Patients with Borderline Personality Disorder: An fMRI Study

    PubMed Central

    Buchheim, Anna; Erk, Susanne; George, Carol; Kächele, Horst; Martius, Philipp; Pokorny, Dan; Spitzer, Manfred; Walter, Henrik

    2016-01-01

    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 (fMRI). Eleven female patients with BPD without posttraumatic stress disorder (PTSD) and 17 healthy female controls matched for age and education were telling stories in the scanner in response to the Adult Attachment Projective Picture System (AAP), 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 2 min. 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 (DLPFC) and the rostral cingulate zone (RCZ). 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. PMID:27531977

  14. Neural Response during the Activation of the Attachment System in Patients with Borderline Personality Disorder: An fMRI Study.

    PubMed

    Buchheim, Anna; Erk, Susanne; George, Carol; Kächele, Horst; Martius, Philipp; Pokorny, Dan; Spitzer, Manfred; Walter, Henrik

    2016-01-01

    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 (fMRI). Eleven female patients with BPD without posttraumatic stress disorder (PTSD) and 17 healthy female controls matched for age and education were telling stories in the scanner in response to the Adult Attachment Projective Picture System (AAP), 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 2 min. 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 (DLPFC) and the rostral cingulate zone (RCZ). 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.

  15. Spontaneous otoacoustic emissions in two gecko species, Gekko gecko and Eublepharis macularius.

    PubMed

    Manley, G A; Gallo, L; Koppl, C

    1996-03-01

    Spontaneous otoacoustic emissions (SPOAE) of the gecko species Gekko gecko and Eublepharis macularius appear as broad spectral peaks (bandwidth 44 to 170 Hz) between 1 and 4.5 kHz that have peak levels of -7 to 10 dB SPL. Most ears showed SPOAE at many frequencies. In some ears, the peaks were superimposed on a broad baseline emission. The instantaneous frequency of any emission varied rapidly within its bandwidth limits and frequencies in the center of the band occurred most commonly, but not with higher levels than frequencies on the periphery of the band. SPOAE were temperature dependent, rising in frequency with an increase in temperature and falling with a decrease in temperature (rate of change from 54 to 107 Hz/degrees C), with no systematic changes in peak level except that at the temperature extremes, the SPOAE disappeared into the noise. External tones suppressed SPOAE peak level in a frequency-dependent way. Isosuppression tuning curves were V-shaped. In restricted frequency ranges, facilitation also occurred. External tones also caused shifts in the frequency of SPOAE; frequency "pushing" was more common than "pulling." The maximal frequency shift observed was 313 Hz. In general, the SPOAE characteristics strongly resemble those already reported in the bobtail lizard Tiliqua rugosa.

  16. A unique method of retaining orbital prosthesis with attachment systems - a clinical report.

    PubMed

    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.

  17. Introduction to the adhesive bonding session. [foam system for attaching thermal insulation on space shuttle

    NASA Technical Reports Server (NTRS)

    Mccarty, J. E.

    1972-01-01

    Space shuttle unique requirements call for the development of a specific adhesive system to reliable attach reusable surface insulation. A low density foam system has been developed that provides strain isolation from the support structure and remains structurally stable in space shuttle thermal environment. Surface preparation and its stabilization by an adhesive primer system are the most important factors in preventing corrosion from reducing the reliability and durability of the adhesive bonding component.

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

    PubMed

    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.

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

    PubMed Central

    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. PMID:27419102

  20. Role of attachment to surfaces on the prevalence and survival of Campylobacter through food systems.

    PubMed

    Nguyen, Vu Tuan; Fegan, Narelle; Turner, Mark S; Dykes, Gary A

    2012-01-01

    Campylobacter continues to be one of the bacterial pathogens most frequently associated with human gastrointestinal illness worldwide. Because Campylobacter primarily colonizes the intestines of animals used for food production, food products of animal origin can become contaminated with this pathogen and thus represent a significant risk factor. Despite application of numerous physical and chemical interventions to control Campylobacter during food processing, the high isolation rate of this pathogen from some retail meat products indicates that Campylobacter is able to persist from animal slaughterhouses through food systems. Given the fastidious growth requirements and high susceptibility of this pathogen to environmental conditions, the ability of Campylobacter to attach to food and food-related surfaces is likely to play an important role in food contamination and movement through food systems. This review was compiled to (i) describe how the attachment of Campylobacter to surfaces influences the prevalence and survival of the organism through food systems, (ii) examine the potential factors affecting the ability of Campylobacter to attach to surfaces, and (iii) suggest strategies for controlling this attachment process.

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

    PubMed

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

    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. Fabrication and Characterization of Gecko-inspired Fibrillar Adhesive

    NASA Astrophysics Data System (ADS)

    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

  3. Effects of the Adult Attachment Projective Picture System on Oxytocin and Cortisol Blood Levels in Mothers.

    PubMed

    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 as

  4. Effects of the Adult Attachment Projective Picture System on Oxytocin and Cortisol Blood Levels in Mothers

    PubMed Central

    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

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

    PubMed Central

    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. PMID:27145027

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

    PubMed

    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.

  7. Comparison of dietary overlap between allopatric and sympatric geckos

    Treesearch

    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...

  8. A Novel Integrating Virtual Reality Approach for the Assessment of the Attachment Behavioral System.

    PubMed

    Chicchi Giglioli, Irene Alice; Pravettoni, Gabriella; Sutil Martín, Dolores Lucia; Parra, Elena; Raya, Mariano A

    2017-01-01

    Virtual reality (VR) technology represents a novel and powerful tool for behavioral research in psychological assessment. VR provides simulated experiences able to create the sensation of undergoing real situations. Users become active participants in the virtual environment seeing, hearing, feeling, and actuating as if they were in the real world. Currently, the most psychological VR applications concern the treatment of various mental disorders but not the assessment, that it is mainly based on paper and pencil tests. The observation of behaviors is costly, labor-intensive, and it is hard to create social situations in laboratory settings, even if the observation of actual behaviors could be particularly informative. In this framework, social stressful experiences can activate various behaviors of attachment for a significant person that can help to control and soothe them to promote individual's well-being. Social support seeking, physical proximity, and positive and negative behaviors represent the main attachment behaviors that people can carry out during experiences of distress. We proposed VR as a novel integrating approach to measure real attachment behaviors. The first studies on attachment behavioral system by VR showed the potentiality of this approach. To improve the assessment during the VR experience, we proposed virtual stealth assessment (VSA) as a new method. VSA could represent a valid and novel technique to measure various psychological attributes in real-time during the virtual experience. The possible use of this method in psychology could be to generate a more complete, exhaustive, and accurate individual's psychological evaluation.

  9. A Novel Integrating Virtual Reality Approach for the Assessment of the Attachment Behavioral System

    PubMed Central

    Chicchi Giglioli, Irene Alice; Pravettoni, Gabriella; Sutil Martín, Dolores Lucia; Parra, Elena; Raya, Mariano A.

    2017-01-01

    Virtual reality (VR) technology represents a novel and powerful tool for behavioral research in psychological assessment. VR provides simulated experiences able to create the sensation of undergoing real situations. Users become active participants in the virtual environment seeing, hearing, feeling, and actuating as if they were in the real world. Currently, the most psychological VR applications concern the treatment of various mental disorders but not the assessment, that it is mainly based on paper and pencil tests. The observation of behaviors is costly, labor-intensive, and it is hard to create social situations in laboratory settings, even if the observation of actual behaviors could be particularly informative. In this framework, social stressful experiences can activate various behaviors of attachment for a significant person that can help to control and soothe them to promote individual’s well-being. Social support seeking, physical proximity, and positive and negative behaviors represent the main attachment behaviors that people can carry out during experiences of distress. We proposed VR as a novel integrating approach to measure real attachment behaviors. The first studies on attachment behavioral system by VR showed the potentiality of this approach. To improve the assessment during the VR experience, we proposed virtual stealth assessment (VSA) as a new method. VSA could represent a valid and novel technique to measure various psychological attributes in real-time during the virtual experience. The possible use of this method in psychology could be to generate a more complete, exhaustive, and accurate individual’s psychological evaluation. PMID:28701967

  10. Preliminary design and simulations of a Shuttle-Attached Manipulator System.

    NASA Technical Reports Server (NTRS)

    Brodie, S. B.; Johnson, C. H.

    1973-01-01

    The preliminary design of a Shuttle-Attached Manipulator System is based on two arms that are articulated at shoulder, elbow, and wrist. Details of manipulator design are considered, giving attention to arm reach, velocity, acceleration, torque, joint angular travel limits, control, crew systems and man-machine interface, and telecommunications. The results of man-in-the-loop simulations show the feasibility of grappling a representative space payload from the Shuttle using a long boom manipulator system. The task, however, is sufficiently difficult to require the full concentration of one operator who should be relieved of any other tasks while performing operations with the manipulator system.

  11. Design and Verification of Space Station EVA-Operated Truss Attachment System

    NASA Technical Reports Server (NTRS)

    Katell, Gabriel

    2001-01-01

    This paper describes the design and verification of a system used to attach two segments of the International Space Station (ISS). This system was first used in space to mate the P6 and Z1 trusses together in December 2000, through a combination of robotic and extravehicular tasks. Features that provided capture, coarse alignment, and fine alignment during the berthing process are described. Attachment of this high value hardware was critical to the ISS's sequential assembly, necessitating the inclusion of backup design and operational features. Astronauts checked for the proper performance of the alignment and bolting features during on-orbit operations. During berthing, the system accommodates truss-to-truss relative displacements that are caused by manufacturing tolerances and on-orbit thermal gradients. After bolt installation, the truss interface becomes statically determinate with respect to in-plane shear loads and isolates attach bolts from bending moments. The approach used to estimate relative displacements and the means of accommodating them is explained. Confidence in system performance was achieved through a cost-effective collection of tests and analyses, including thermal, structural, vibration, misalignment, contact dynamics, underwater simulation, and full-scale functional testing. Design considerations that have potential application to other mechanisms include accommodating variations of friction coefficients in the on-orbit joints, wrench torque tolerances, joint preload, moving element clearances at temperature extremes, and bolt-nut torque reaction.

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

    PubMed

    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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

  16. Powered orthosis and attachable power-assist device with Hydraulic Bilateral Servo System.

    PubMed

    Ohnishi, Kengo; Saito, Yukio; Oshima, Toru; Higashihara, Takanori

    2013-01-01

    This paper discusses the developments and control strategies of exoskeleton-type robot systems for the application of an upper limb powered orthosis and an attachable power-assist device for care-givers. Hydraulic Bilateral Servo System, which consist of a computer controlled motor, parallel connected hydraulic actuators, position sensors, and pressure sensors, are installed in the system to derive the joint motion of the exoskeleton arm. The types of hydraulic component structure and the control strategy are discussed in relation to the design philosophy and target joints motions.

  17. System and method for changing a glove attached to a glove box

    DOEpatents

    Aluisi, Alan

    2001-01-01

    A system for changing the gloves of a glove box. The system requires the use of a new glove and a glove change ring to form a temporary secondary barrier to the exchange of atmospheres between the inner glove box and the room in which the glove box is operated. The system describes specific means for disengaging a used glove from the glove box port. The means for disengaging the used glove include use of a glove change hook and use of a glove with an attached tab for use in removal. A method for changing the gloves of a glove box is also described.

  18. Hitchhiker-G: A new carrier system for attached shuttle payloads

    NASA Technical Reports Server (NTRS)

    Goldsmith, T. C.

    1987-01-01

    A new carrier system has been developed for economical and quick response flight of small attached payloads on the space shuttle. Hitchhiker-G can accommodate up to 750 lb. of customer payloads in canisters or mounted to an exposed plate. The carrier connects to the orbiter's electrical systems and provides up to six customers with standard electrical services including power, real time telemetry, and commands. A transparent data and command system concept is employed to allow the customer to easily use his own ground support equipment and personnel to control his payload during integration and flight operations. The first Hitchhiker-G was successfully flown in January 1986 on STS 61C.

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

    PubMed

    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

  20. Implant-supported overdenture with prefabricated bar attachment system in mandibular edentulous patient

    PubMed Central

    Ha, Seung-Ryong; Song, Seung-Il; Hong, Seong-Tae; Kim, Gy-Young

    2012-01-01

    Implant-supported overdenture is a reliable treatment option for the patients with edentulous mandible when they have difficulty in using complete dentures. Several options have been used for implant-supported overdenture attachments. Among these, bar attachment system has greater retention and better maintainability than others. SFI-Bar® is prefabricated and can be adjustable at chairside. Therefore, laboratory procedures such as soldering and welding are unnecessary, which leads to fewer errors and lower costs. A 67-year-old female patient presented, complaining of mobility of lower anterior teeth with old denture. She had been wearing complete denture in the maxilla and removable partial denture in the mandible with severe bone loss. After extracting the teeth, two implants were placed in front of mental foramen, and SFI-Bar® was connected. A tube bar was seated to two adapters through large ball joints and fixation screws, connecting each implant. The length of the tube bar was adjusted according to inter-implant distance. Then, a female part was attached to the bar beneath the new denture. This clinical report describes two-implant-supported overdenture using the SFI-Bar® system in a mandibular edentulous patient. PMID:23236580

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

    PubMed Central

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

    2014-01-01

    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. PMID:23201031

  2. Impact of Child Maltreatment on Attachment and Social Rank Systems: Introducing an Integrated Theory.

    PubMed

    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.

  3. Attachment Without Fear.

    PubMed

    Bell, David C

    2009-12-01

    John Bowlby hypothesized an attachment system that interacts with caregiving, exploration, and fear systems in the brain, with a particular emphasis on fear. Neurobiological research confirms many of his hypotheses and also raises some new questions. A psychological model based on this neurobiological research is presented here. The model extends conventional attachment theory by describing additional attachment processes independent of fear. In this model, the attachment elements of trust, openness, and dependence interact with the caregiving elements of caring, empathy, and responsibility.

  4. Skull anatomy of the miniaturized gecko Sphaerodactylus roosevelti (Squamata: Gekkota).

    PubMed

    Daza, Juan D; Abdala, Virginia; Thomas, Richard; Bauer, Aaron M

    2008-11-01

    A detailed description of the skull and jaw of the gecko Sphaerodactylus roosevelti is presented. The bones are described articulated and isolated with special consideration given to the type of suture among joining elements. S. roosevelti was compared with 109 gekkotan species to evaluate the osteological variation and to find characters for cladistic analysis. Changes in the skull associated with the miniaturization process are discussed within the sphaerodactylid geckos. A noticeable increase of overlapping sutures was observed in the snout of the smallest sphaerodactylids compared to other gekkotans. This pattern is convergent with that in miniaturized pygopodids and may be attributed to adaptations for decreasing mechanical resistance of the cranium during feeding or burrowing. New cranial characters support Sphaerodactylinae as a monophyletic group and should be useful for resolving questions such as their relationship with other gekkotans.

  5. Modeling Stimulus-Frequency Otoacoustic Emissions in the Gecko

    NASA Astrophysics Data System (ADS)

    Bergevin, Christopher; Shera, Christopher A.

    2009-02-01

    Although lizards lack the basilar-membrane traveling waves evident in mammals, their ears produce stimulus-frequency otoacoustic emissions (SFOAEs) with latencies comparable to those measured in many mammals (1-2 ms or greater). To probe the origin of these relatively long OAE delays, we developed a model of SFOAE generation in the gecko. The model inner ear comprises a collection of linear, coupled oscillators (hair bundles and associated tectorium) whose effective damping manifests a small degree of irregularity. The model reproduces the major qualitative features of gecko SFOAEs, including their substantial delays. The SFOAE delays predicted by the model increase with the assumed sharpness of tuning, reflecting the build-up time associated with mechanical resonance.

  6. Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens.

    PubMed Central

    Matthysse, A G; Yarnall, H A; Young, N

    1996-01-01

    Transposon mutants of Agrobacterium tumefaciens which were avirulent and unable to attach to plant cells were isolated and described previously. A clone from a library of Agrobacterium tumefaciens DNA which was able to complement these chromosomal att mutants was identified. Tn3HoHo1 insertions in this clone were made and used to replace the wild-type genes in the bacterial chromosome by marker exchange. The resulting mutants were avirulent and showed either no or very much reduced attachment to carrot suspension culture cells. We sequenced a 10-kb region of this clone and found a putative operon containing nine open reading frames (ORFs) (attA1A2BCDEFGH). The second and third ORFs (attA2 and attB) showed homology to genes encoding the membrane-spanning proteins (potB and potH; potC and potI) of periplasmic binding protein-dependent (ABC) transport systems from gram-negative bacteria. The homology was strongest to proteins involved in the transport of spermidine and putrescine. The first and fifth ORFs (attA1 and attE) showed homology to the genes encoding ATP-binding proteins of these systems including potA, potG, and cysT from Escherichia coli; occP from A. tumefaciens; cysA from Synechococcus spp.; and ORF-C from an operon involved in the attachment of Campylobacte jejuni. The ability of mutants in these att genes to bind to host cells was restored by addition of conditioned medium during incubation of the bacteria with host cells. PMID:8752352

  7. Requirement for genes with homology to ABC transport systems for attachment and virulence of Agrobacterium tumefaciens.

    PubMed

    Matthysse, A G; Yarnall, H A; Young, N

    1996-09-01

    Transposon mutants of Agrobacterium tumefaciens which were avirulent and unable to attach to plant cells were isolated and described previously. A clone from a library of Agrobacterium tumefaciens DNA which was able to complement these chromosomal att mutants was identified. Tn3HoHo1 insertions in this clone were made and used to replace the wild-type genes in the bacterial chromosome by marker exchange. The resulting mutants were avirulent and showed either no or very much reduced attachment to carrot suspension culture cells. We sequenced a 10-kb region of this clone and found a putative operon containing nine open reading frames (ORFs) (attA1A2BCDEFGH). The second and third ORFs (attA2 and attB) showed homology to genes encoding the membrane-spanning proteins (potB and potH; potC and potI) of periplasmic binding protein-dependent (ABC) transport systems from gram-negative bacteria. The homology was strongest to proteins involved in the transport of spermidine and putrescine. The first and fifth ORFs (attA1 and attE) showed homology to the genes encoding ATP-binding proteins of these systems including potA, potG, and cysT from Escherichia coli; occP from A. tumefaciens; cysA from Synechococcus spp.; and ORF-C from an operon involved in the attachment of Campylobacte jejuni. The ability of mutants in these att genes to bind to host cells was restored by addition of conditioned medium during incubation of the bacteria with host cells.

  8. Nutritional degenerative myopathy in a population of captive bred Uroplatus phantasticus (satanic leaf-tailed geckoes).

    PubMed

    Les Gabor, J

    2005-01-01

    Severe generalized degenerative myopathy was diagnosed in a population of captive bred satanic leaf-tailed geckoes (Uroplatus phantasticus). The diagnosis was based on characteristic histological changes and response to dietary therapy. This is the first reported case of nutritional myopathy in the satanic leaf-tailed gecko.

  9. Technical note: Effects of attachment of hind teats before cleaning and attachment of front teats on milking characteristics in automatic milking systems.

    PubMed

    Besier, J; Schüpbach-Regula, G; Wellnitz, O; Bruckmaier, R M

    2017-04-01

    Milking characteristics differ between the 4 quarters of a dairy cow udder. In particular, milking time is mostly prolonged in hind quarters compared with front quarters because of the usually higher amount of stored milk. The standard milking routine (STDMR) in both conventional and automatic milking systems (AMS) consists of teat preparation of all 4 quarters, followed by attachment of the 4 teat cups, regardless of the distribution of milk between quarters. In the current study, an alternative teat preparation and milking routine (ALTMR) in AMS was tested, which consisted of cleaning and starting the milking of hind teats before cleaning and attachment of front teats. The hypothesis was based on the fact that hind quarters have usually a longer milking time than front quarters. Starting the milking of hind quarters while the front teats are being cleaned may reduce the difference in the end of milking between front and hind quarters and thus reduce total milking time. Both routines were tested on 5 Swedish dairy farms equipped with AMS in a 4-wk experiment in which treatments were alternated weekly. Total milk yield did not differ between treatments. Machine-on time (MOT) was longer in ALTMR than in STDMR because the difference in milking time between hind and front quarters was less than the time needed to prepare the front teats. However, the longer MOT in ALTMR was compensated by a shorter total preparation time, including the attachment of the first teat cup, as only the hind teats (instead of all 4 teats) were cleaned before milking was started. This resulted in a similar total milking time from start of cleaning of the first quarter until the end of milking of the last quarter in both treatments. Because of the prolonged MOT, average milk flow rate was lower in ALTMR than STDMR. Peak flow rate was higher in ALTMR than STDMR, but only in teat cups 1 (first attached, hind quarter) and 3 (third attached, front quarter), whereas main milk flow was higher in

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

    SciTech Connect

    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's Center for High Technology

  11. Developmental Neurobiology of the Rat Attachment System and Its Modulation by Stress

    PubMed Central

    Bisaz, Reto; Sullivan, Regina M.

    2012-01-01

    Stress is a powerful modulator of brain structure and function. While stress is beneficial for survival, inappropriate stress dramatically increases the risk of physical and mental health problems, particularly when experienced during early developmental periods. Here we focus on the neurobiology of the infant rat’s odor learning system that enables neonates to learn and approach the maternal odor and describe the unique role of the stress hormone corticosterone in modulating this odor approach learning across development. During the first nine postnatal days, this odor approach learning of infant rats is supported by a wide range of sensory stimuli and ensures attachment to the mother’s odor, even when interactions with her are occasionally associated with pain. With maturation and the emergence of a stress- or pain-induced corticosterone response, this odor approach learning terminates and a more adult-like amygdala-dependent fear/avoidance learning emerges. Strikingly, the odor approach and attenuated fear learning of older pups can be re-established by the presence of the mother, due to her ability to suppress her pups’ corticosterone release and amygdala activity. This suggests that developmental changes in stress responsiveness and the stimuli that produce a stress response might be critically involved in optimally adapting the pup’s attachment system to its respective ecological niche. PMID:23626910

  12. NAFFS: network attached flash file system for cloud storage on portable consumer electronics

    NASA Astrophysics Data System (ADS)

    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.

  13. Use of the Adult Attachment Projective Picture System in an assessment of an adolescent in foster care.

    PubMed

    Webster, Linda; Joubert, David

    2011-01-01

    Child maltreatment has been associated with a host of negative outcomes including impaired social relationships (Rogosch, Cicchetti, & Aber, 1995), depression (Toth, Manly, & Cicchetti, 1992), poor self-concept and motivation (Vondra, Barnett, & Cicchetti, 1990), and delinquency and conduct problems (Cook et al., 2005; Grotevant et al., 2006; McCabe, Lucchini, Hough, Yeh, & Hazen, 2005; Ryan & Testa, 2005). An assessment of the mental representation of attachment relationships could offer additional relevant and useful information to the evaluation of youth in foster care, and could inform treatment and placement considerations. The Adult Attachment Projective Picture System (AAP) is a relatively new measure of internal representations of attachment based on the analysis of a set of stimuli designed to systematically activate the attachment system (George, West, & Pettem, 1997). This article considers the use of the AAP with a maltreated adolescent in a clinical setting and uses a case study to illustrate the components of the AAP that are particularly relevant to case conceptualization and interventions.

  14. Role of the family in suicide prevention: an attachment and family systems perspective.

    PubMed

    Lobo Prabhu, Sheila; Molinari, Victor; Bowers, Theron; Lomax, James

    2010-01-01

    Suicide can be an act of despair, anger, or escape from intolerable pain associated with prior bonding disturbances within the family system, interpersonal loss, and current perceived lack of social support. Using a variety of online databases, the authors examined the research on the family's role in preventing suicide from an attachment and family systems perspective. They found relevant articles describing how to make use of family support in suicide prevention. From a study of the literature, the authors outline three new family concepts in suicide prevention: family cohesion, family adhesion, and formation of a new family. Therapists should use every familial resource to avoid premature closure and to expand perception of support options. The authors suggest specific practice recommendations to successfully involve families in suicide prevention based on the outlined family conceptual framework, and they recommend research investigation to determine empirical validation of these tentative formulations.

  15. Why social attachment and oxytocin protect against addiction and stress: Insights from the dynamics between ventral and dorsal corticostriatal systems.

    PubMed

    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.

  16. Nuclear reactor fuel assembly duct-tube-to-inlet-nozzle attachment system

    DOEpatents

    Christiansen, David W.; Smith, Bob G.

    1982-01-01

    A reusable system for removably attaching the lower end 21 of a nuclear reactor fuel assembly duct tube to an upper end 11 of a nuclear reactor fuel assembly inlet nozzle. The duct tube's lower end 21 has sides terminating in locking tabs 22 which end in inwardly-extending flanges 23. The flanges 23 engage recesses 13 in the top section 12 of the inlet nozzle's upper end 11. A retaining collar 30 slides over the inlet nozzle's upper end 11 to restrain the flanges 23 in the recesses 13. A locking nut 40 has an inside threaded portion 41 which engages an outside threaded portion 15 of the inlet nozzle's upper end 11 to secure the retaining collar 30 against protrusions 24 on the duct tube's sides.

  17. Peer attachment formation by systemic redox regulation with social training after a sensitive period

    PubMed Central

    Koshiba, Mamiko; Karino, Genta; Senoo, Aya; Mimura, Koki; Shirakawa, Yuka; Fukushima, Yuta; Obara, Saya; Sekihara, Hitomi; Ozawa, Shimpei; Ikegami, Kentaro; Ueda, Toyotoshi; Yamanouchi, Hideo; Nakamura, Shun

    2013-01-01

    Attachment formation is the most pivotal factor for humans and animals in the growth and development of social relationships. However, the developmental processes of attachment formation mediated by sensory-motor, emotional, and cognitive integration remain obscure. Here we developed an animal model to understand the types of social interactions that lead to peer-social attachment formation. We found that the social interaction in a sensitive period was essential to stabilise or overwrite the initially imprinted peer affiliation state and that synchronised behaviour with others based on common motivations could be a driver of peer social attachment formation. Furthermore, feeding experience with supplementation of ubiquinol conferred peer social attachment formation even after the sensitive period. Surprisingly, the experience of feeding beyond the cage window was also effective to reduce the required amount ubiquinol, suggesting that peri-personal space modulation may affect socio-emotional cognition and there by lead to attachment formation. PMID:23974241

  18. Peer attachment formation by systemic redox regulation with social training after a sensitive period.

    PubMed

    Koshiba, Mamiko; Karino, Genta; Senoo, Aya; Mimura, Koki; Shirakawa, Yuka; Fukushima, Yuta; Obara, Saya; Sekihara, Hitomi; Ozawa, Shimpei; Ikegami, Kentaro; Ueda, Toyotoshi; Yamanouchi, Hideo; Nakamura, Shun

    2013-01-01

    Attachment formation is the most pivotal factor for humans and animals in the growth and development of social relationships. However, the developmental processes of attachment formation mediated by sensory-motor, emotional, and cognitive integration remain obscure. Here we developed an animal model to understand the types of social interactions that lead to peer-social attachment formation. We found that the social interaction in a sensitive period was essential to stabilise or overwrite the initially imprinted peer affiliation state and that synchronised behaviour with others based on common motivations could be a driver of peer social attachment formation. Furthermore, feeding experience with supplementation of ubiquinol conferred peer social attachment formation even after the sensitive period. Surprisingly, the experience of feeding beyond the cage window was also effective to reduce the required amount ubiquinol, suggesting that peri-personal space modulation may affect socio-emotional cognition and there by lead to attachment formation.

  19. The effect of the nurturant bonding system on child security of attachment and dependency.

    PubMed

    Miller, Warren B; Feldman, Shirley S; Pasta, David J

    2002-01-01

    This paper uses a biopsychosocial theory of human bonding to explore the intergenerational transmission of bonding traits. More specifically, it examines how the nurturant bonding system of the mother affects the succorant bonding system of the young child. In the first section of the paper, we take the bonding framework proposed by Miller and Rodgers (2001) and elaborate its implications for mother-child dyads. Next, we describe the collection of data from 78 mothers prior to their pregnancy with an index child and again when that child is between the ages of two and four and a half. These data allow the creation of a number of mother and child variables that are derived from the bonding framework. Using these variables, we construct a temporally organized, structural equation model of maternal effects on the child, with the two main outcome variables being child security of attachment and child dependency. We then test the model using LISREL. Although the results are tentative and require further confirmatory research, they lend support to three broad hypotheses derived from the bonding framework. In particular, the results support the construct of a motivational substrate that affects both maternal childbearing and her child-rearing behaviors. They also indicate the importance of child temperament in the formation of the succorant bond. Finally, they demonstrate that the preconception nurturant characteristics of the mother have multiple effects on the two main outcome variables, child security of attachment and dependency. Two submodels based on predictors of these two outcomes reveal a number of pathways along which these effects take place. We conclude with a brief discussion of the lessons learned that might strengthen future studies of mother-child bonding and, more generally, the intergenerational transmission of bonding traits.

  20. Image Analysis of Chlorophyll Fluorescence Transients for Diagnosing the Photosynthetic System of Attached Leaves

    PubMed Central

    Omasa, Kenji; Shimazaki, Ken-Ichiro; Aiga, Ichiro; Larcher, Walter; Onoe, Morio

    1987-01-01

    A new image instrumentation system for quantitative analysis of the rapid change in intensity of chlorophyll fluorescence during dark-light transition (CFI, chlorophyll fluorescence induction), which is a sensitive indicator of the various reactions of photosynthesis, was developed and its performance was evaluated. This system made it possible to resolve CFI at any small leaf area (about 1 square millimeter) of a whole leaf when the plant was illuminated by blue-green light at more than 50 micromoles photons per square meter per second. In order to test the usefulness of this system, we applied it to analyze the effect of SO2 on photosynthetic apparatus in attached sunflower leaves. Dynamic CFI imaging over the whole single leaf, where there was no visible injury, indicated not only the local changes in photosynthetic activity but also the site of inhibition in photosynthetic electron transport system in chloroplasts. The new instrumentation system will be useful for the analytical diagnosis of various stress-actions on plants in situ. Images Fig. 1 Fig. 5 Fig. 6 PMID:16665515

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

    PubMed

    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.

  2. Effects of loading and size on maximum power output and gait characteristics in geckos.

    PubMed

    Irschick, Duncan J; Vanhooydonck, Bieke; Herrel, Anthony; Andronescu, Anemone

    2003-11-01

    Stride length, stride frequency and power output are all factors influencing locomotor performance. Here, we first test whether mass-specific power output limits climbing performance in two species of geckos (Hemidactylus garnoti and Gekko gecko) by adding external loads to their bodies. We then test whether body size has a negative effect on mass-specific power output. Finally, we test whether loading affects kinematics in both gecko species. Lizards were induced to run vertically on a smooth wooden surface with loads of 0-200% of body mass (BM) in H. garnoti and 0-100% BM in G. gecko. For each stride, we calculated angular and linear kinematics (e.g. trunk angle, stride length), performance (maximum speed) and mean mass-specific power output per stride. The addition of increasingly large loads caused an initial increase in maximum mass-specific power output in both species, but for H. garnoti, mass-specific power output remained constant at higher loads (150% and 200% BM), even though maximum velocity declined. This result, in combination with the fact that stride frequency showed no evidence of leveling off as speed increased in either species, suggests that power limits maximum speed. In addition, the large gecko (G. gecko) produced significantly less power than the smaller H. garnoti, despite the fact that both species ran at similar speeds. This difference disappeared, however, when we recalculated power output based on higher maximum speeds for unloaded G. gecko moving vertically obtained by other researchers. Finally, the addition of external loads did not affect speed modulation in either species: both G. gecko and H. garnoti increase speed primarily by increasing stride frequency, regardless of loading condition. For a given speed, both species take shorter but more strides with heavier loads, but for a given load, G. gecko attains similar speeds to H. garnoti by taking longer but fewer strides.

  3. Enhanced adhesion by gecko-inspired hierarchical fibrillar adhesives.

    PubMed

    Murphy, Michael P; Kim, Seok; Sitti, Metin

    2009-04-01

    The complex structures that allow geckos to repeatably adhere to surfaces consist of multilevel branching fibers with specialized tips. We present a novel technique for fabricating similar multilevel structures from polymer materials and demonstrate the fabrication of arrays of two- and three-level structures, wherein each level terminates in flat mushroom-type tips. Adhesion experiments are conducted on two-level fiber arrays on a 12-mm-diameter glass hemisphere, which exhibit both increased adhesion and interface toughness over one-level fiber samples and unstructured control samples. These adhesion enhancements are the result of increased surface conformation as well as increased extension during detachment.

  4. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor...

  5. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor...

  6. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

  7. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

  8. 24 CFR 350.11 - Notice of Attachment for Ginnie Mae Securities in Book-entry System.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Securities in Book-entry System. 350.11 Section 350.11 Housing and Urban Development Regulations Relating to... AND URBAN DEVELOPMENT BOOK-ENTRY PROCEDURES § 350.11 Notice of Attachment for Ginnie Mae Securities in Book-entry System. The interest of a debtor in a Security Entitlement may be reached by a creditor only...

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

    PubMed

    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.

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

    PubMed

    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.

  11. Imaging diagnosis-pulmonary-tracheobronchial prolapse in a new Caledonian giant gecko (Rhacodactylus leachianus).

    PubMed

    Hoey, Seamus; Keller, Dominique; Chamberlin, Tamara; Pinkerton, Marie; Waller, Kenneth; Drees, Randi

    2013-01-01

    A 3-year-old male New Caledonian giant gecko, or Leach's gecko (Rhacodactylus leachianus) presented with acute lethargy and coelomic distention. Findings from survey radiographs and an upper gastrointestinal tract contrast study were consistent with severe aerophagia, a collapsed left lung, and hyperinflation of the right lung due to suspected bronchial obstruction. The gecko was treated with conservative medical management, but was found dead 5 days after presentation. Necropsy findings showed intussusception of the proximal left lung into the left mainstem bronchus and trachea.

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

    PubMed

    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. Shape-memory alloy overload protection device for osseointegrated transfemoral implant prosthetic limb attachment system

    NASA Astrophysics Data System (ADS)

    Xu, Wei; Shao, Fei; Hughes, Steven

    2002-11-01

    The osseointegrated trans-femoral implant system provides a direct anchoring technique to attach prosthetic limb. This technique was first introduced PI Brenmark in Sweden. The UK had the first clinical trial in 1997 and currently has 6 active limb wearers. The success of this procedure has the potential for improved gait function and mobility, increased employability and significant long-term improvements in the quality of life for above knee amputees. However, the significant load involved in the trans-femoral implant system has caused permanent deformation and/or fractures of the implant abutment in several occasions. To protect the implant system, the implant abutment in particularly, an overloading protection device was introduced. The device uses mechanical mechanism to release torsion overload on the abutment. However, the bending overload protection remains unsolved. To solve the problem, a new overload protection device was developed. This device uses SMA component for bending overload protection. In this paper, the results of non-linear finite element modelling of the SMA and steel (AISI 1040) components were presented. Experiments were also carried out using steel components to assess the design which is based on the non-linear property of the materials.

  14. Simulating adverse event spontaneous reporting systems as preferential attachment networks: application to the Vaccine Adverse Event Reporting System.

    PubMed

    Scott, J; Botsis, T; Ball, R

    2014-01-01

    Spontaneous Reporting Systems [SRS] are critical tools in the post-licensure evaluation of medical product safety. Regulatory authorities use a variety of data mining techniques to detect potential safety signals in SRS databases. Assessing the performance of such signal detection procedures requires simulated SRS databases, but simulation strategies proposed to date each have limitations. We sought to develop a novel SRS simulation strategy based on plausible mechanisms for the growth of databases over time. We developed a simulation strategy based on the network principle of preferential attachment. We demonstrated how this strategy can be used to create simulations based on specific databases of interest, and provided an example of using such simulations to compare signal detection thresholds for a popular data mining algorithm. The preferential attachment simulations were generally structurally similar to our targeted SRS database, although they had fewer nodes of very high degree. The approach was able to generate signal-free SRS simulations, as well as mimicking specific known true signals. Explorations of different reporting thresholds for the FDA Vaccine Adverse Event Reporting System suggested that using proportional reporting ratio [PRR] > 3.0 may yield better signal detection operating characteristics than the more commonly used PRR > 2.0 threshold. The network analytic approach to SRS simulation based on the principle of preferential attachment provides an attractive framework for exploring the performance of safety signal detection algorithms. This approach is potentially more principled and versatile than existing simulation approaches. The utility of network-based SRS simulations needs to be further explored by evaluating other types of simulated signals with a broader range of data mining approaches, and comparing network-based simulations with other simulation strategies where applicable.

  15. Reliability Improvement of Ground Fault Protection System Using an S-Type Horn Attachment Gap in AC Feeding System

    NASA Astrophysics Data System (ADS)

    Ajiki, Kohji; Morimoto, Hiroaki; Shimokawa, Fumiyuki; Sakai, Shinya; Sasaki, Kazuomi; Sato, Ryogo

    Contact wires used in feeding system for electric railroad are insulated by insulators. However, insulation of an insulator sometimes breaks down by surface dirt of an insulator and contact with a bird. The insulator breakdown derives a ground fault in feeding system. Ground fault will cause a human electric shock and a destruction of low voltage electric equipment. In order to prevent the damage by ground fault, an S-type horn has been applicable as equipped on insulators of negative feeder and protective wire until present. However, a concrete pole breaks down at the time of the ground fault because a spark-over voltage of the S-type horn is higher than a breakdown voltage of a concrete pole. Farther, the S-type horn installed in the steel tube pole does not discharge a case, because the earth resistance of a steel tube pole is very small. We assumed that we could solve these troubles by changing the power frequency spark-over voltage of the S-type horn from 12kV to 3kV. Accordingly, we developed an attachment gap that should be used to change the power frequency spark-over voltage of the S-type horn from 12kV to 3kV. The attachment gap consists of a gas gap arrester and a zinc oxide element. By the dynamic current test and the artificial ground fault test, we confirmed that the attachment gap in the S-type horn could prevent a trouble at the time of the ground fault.

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

    PubMed

    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.

  17. Queued History based Mediator Identification for an Incentive Attached peer to peer Electronic Coupon System

    NASA Astrophysics Data System (ADS)

    Shojima, Taiki; Ikkai, Yoshitomo; Komoda, Norihisa

    An incentive attached peer to peer (P2P) electronic coupon system is proposed in which users forward e-coupons to potential users by providing incentives to those mediators. A service provider needs to acquire distribution history for incentive payment by recording UserIDs (UIDs) in the e-coupons, since this system is intended for pure P2P environment. This causes problems of dishonestly altering distribution history. In order to solve such problems, distribution history is realized in a couple of queues structure. They are the UID queue, and the public key queue. Each element of the UID queue at the initial state consists of index, a secret key, and a digital signature. In recording one's UID, the encrypted UID is enqueued to the UID queue with a new digital signature created by a secret key of the dequeued element, so that each UID cannot be altered. The public key queue provides the functionality of validating digital signatures on mobile devices. This method makes it possible both each UID and sequence of them to be certificated. The availability of the method is evaluated by quantifying risk reduction using Fault Tree Analysis (FTA). And it's recognized that the method is better than common encryption methods.

  18. Biohydrogen production in the suspended and attached microbial growth systems from waste pastry hydrolysate.

    PubMed

    Han, Wei; Hu, Yunyi; Li, Shiyi; Li, Feifei; Tang, Junhong

    2016-10-01

    Waste pastry was hydrolyzed by glucoamylase and protease which were obtained from solid state fermentation of Aspergillus awamori and Aspergillus oryzae to produce waste pastry hydrolysate. Then, the effects of hydraulic retention times (HRTs) (4-12h) on hydrogen production rate (HPR) in the suspended microbial growth system (continuous stirred tank reactor, CSTR) and attached microbial growth system (continuous mixed immobilized sludge reactor, CMISR) from waste pastry hydrolysate were investigated. The maximum HPRs of CSTR (201.8mL/(h·L)) and CMISR (255.3mL/(h·L)) were obtained at HRT of 6h and 4h, respectively. The first-order reaction could be used to describe the enzymatic hydrolysis of waste pastry. The carbon content of the waste pastry remained 22.8% in the undigested waste pastry and consumed 77.2% for carbon dioxide and soluble microbial products. To our knowledge, this is the first study which reports biohydrogen production from waste pastry. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Performance of suspended and attached growth MBR systems in treating high strength synthetic wastewater.

    PubMed

    Jamal Khan, S; Ilyas, Shazia; Javid, Sadaf; Visvanathan, C; Jegatheesan, V

    2011-05-01

    The performance of laboratory-scale attached growth (AG) and suspended growth (SG) membrane bioreactors (MBRs) was evaluated in treating synthetic wastewater simulating high strength domestic wastewater. This study investigated the influence of sponge suspended carriers in AG-MBR system, occupying 15% reactor volume, on the removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP), and compared it to that of SG-MBR. Results showed that the removal efficiencies of COD, TN and TP in AG-MBR were 98%, 89% and 58%, respectively as compared to 98%, 74% and 38%, respectively in SG-MBR. Improved TN removal in AG-MBR systems was primarily based on simultaneous nitrification and denitrification (SND) process. These results infer that the presence of small bio-particles having higher microbial activity and the growth of complex biomass captured within the suspended sponge carriers resulted in improved TN and TP removal in AG-MBR. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Attachment Without Fear

    PubMed Central

    Bell, David C.

    2012-01-01

    John Bowlby hypothesized an attachment system that interacts with caregiving, exploration, and fear systems in the brain, with a particular emphasis on fear. Neurobiological research confirms many of his hypotheses and also raises some new questions. A psychological model based on this neurobiological research is presented here. The model extends conventional attachment theory by describing additional attachment processes independent of fear. In this model, the attachment elements of trust, openness, and dependence interact with the caregiving elements of caring, empathy, and responsibility. PMID:22879835

  1. Coverage error of gingival shade guide systems in measuring color of attached anterior gingiva

    PubMed Central

    Bayindir, Funda; Bayindir, Yusuf Ziya; Gozalo-Diaz, David J.; Wee, Alvin G.

    2009-01-01

    Statement of problem It remains unclear which gingival shade guide is most effective in producing the best visual shade match. Purpose The purpose of this study was to determine and compare the coverage errors (CEs) of 2 different gingival shade guides and their combination in a selected population. Material and methods The CEs of the following gingival shade guides were evaluated: (1) Lucitone 199, (2) IPS Gingiva, and (3) a combination of the 2 shade guide systems. The spectral reflectance values of the center of each gingival shade tab (1.5 mm in diameter) were measured (without a backing) with a spectroradiometer and an external light source at wavelengths from 380 nm to 780 nm at 2-nm intervals. All spectral reflectance measurements were made using 0-degree observer and 45-degree illumination and then converted to CIE values. The attached gingiva of 120 subjects was measured with the same protocol. The CEs of each of the 120 subjects’ attached gingiva for each of the 2 shade guide systems and their combination were determined and averaged. The mean minimum CEs were analyzed with repeated measures ANOVA and the post hoc Tukey HSD for multiple comparison (α =.05). Results A significant difference (P<.001) was found among the mean minimum CEs of the 2 gingival shade guide systems and their combination. The Tukey HSD test revealed that the mean minimum CEs for Lucitone 199 (ΔE 10.8 ± 4.4) were significantly different from the IPS Gingiva (ΔE 8.6 ± 3.6) shade guide system. However, the combination of the 2 gingival shade guide systems (ΔE 7.9 ± 3.4) was not significantly different from the IPS Gingiva system, but a significant difference was found among races (P=.016). No interactions were found between the other tested groups. The mean CE for white individuals (ΔE 8.3 ± 2.5) is significantly different and less than the mean CE for African Americans (ΔE 10.0 ± 4.4). The CEs for Asians (ΔE=9.1 ± 4.3) and others (ΔE 9.0 ± 4.4) are not significantly

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

    PubMed

    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.

  3. Condensation Risk of Mechanically Attached Roof Systems in Cold Climate Zones

    SciTech Connect

    Pallin, Simon B

    2013-01-01

    systems with thermoplastic membranes are prone to be more effected by interior air intrusion into the roof construction; both due to the wind induced pressure differences and due to the flexibility and elasticity of the membrane (Molleti, Baskaran, Kalinger, & Beaulieu, 2011). Depending on the air permeability of the material underneath the membrane, wind forces increase the risk of fluttering (also referred as billowing) of the thermoplastic membrane. Expectably, the wind induced pressure differences creates a convective air flow into the construction i.e. Page 2 air intrusion. If the conditions are right, moisture from the exchanging air may condensate on surfaces with a temperature below dew-point. The definite path of convective airflows through the building envelope is usually very difficult to determine and therefore simplified models (K nzel, Zirkelbach, & Scfafaczek, 2011) help to estimate an additional moisture loads as a result of the air intrusion. The wind uplifting pressure in combination with wind gusts are important factors for a fluttering roof. Unfortunately, the effect from a fluctuating wind is difficult to estimate as this is a highly dynamic phenomenon and existing standards (ASTM, 2011a) only take into account a steady state approach i.e. there is no guidance or regulations on how to estimate the air intrusion rate. Obviously, a more detailed knowledge on the hygrothermal performance of mechanically attached cool roof system is requested; in consideration to varying surface colors, roof air tightness, climate zones and indoor moisture supply.

  4. A new species of gecko (Squamata: Diplodactylidae: Strophurus) from north Queensland, Australia.

    PubMed

    Vanderduys, Eric

    2016-06-01

    A new species of diplodactylid gecko in the genus Strophurus Fitzinger, from north Queensland, Australia, is described herein as Strophurus congoo sp. nov. It is a small, pale grey to tan, unpatterned or faintly striped gecko, resembling the phasmid geckos in appearance, habitat and behaviour. However, within Strophurus it is not closely related to the phasmid geckos. It is distinguished from all other Strophurus by a combination of even scalation, dull colouration, small size and short tail length. It is only known to occur in a restricted area of the northern Great Dividing Range, within the Einasleigh Uplands bioregion, in a relatively infertile area of rolling, largely granitic hills, and is only known from spinifex (Triodia) hummock grasslands in open woodland.

  5. In-Home Treatment of Reactive Attachment Disorder in a Therapeutic Foster Care System: A Case Example.

    ERIC Educational Resources Information Center

    Sheperis, Carl J.; Renfro-Michel, Edina L.; Doggett, R. Anthony

    2003-01-01

    When trauma precedes a child's placement in the foster care system, it can lead to lasting mental health difficulties. Often, children who experience extreme, chronic trauma prior to age 5 develop Reactive Attachment Disorder (RAD). This article discusses the characteristics of RAD as well as diagnostic criteria and possible etiology. (Contains 26…

  6. Use of the Adult Attachment Projective Picture System (AAP) in the middle of a long-term psychotherapy.

    PubMed

    Finn, Stephen E

    2011-01-01

    This article relates how the Adult Attachment Projective Picture System (AAP) was used as a midtherapy intervention with a middle-aged man being treated for relationship difficulties. The man, who was identified via the AAP as having a dismissing attachment status, had difficulties committing to psychotherapy, presumably because he was terrified of experiencing the underlying depression and grief revealed on his Rorschach and AAP. Reading an AAP-based description of his attachment status helped the man become aware of his characteristic defenses against painful affect, and gave him the motivation to stay in therapy while experiencing and getting support for his unresolved mourning. This work led to the man's experiencing less ambivalence about intimate relationships. There are several important ways that the AAP augments a traditional personality assessment battery and is useful in conducting a long-term psychotherapy.

  7. In search of an adult attachment stress provocation to measure effect on the oxytocin system: A pilot validation study

    PubMed Central

    Munro, Michelle L.; Brown, Stephanie L.; Pournajafi-Nazarloo, Hossein; Carter, C. Sue; Lopez, William D.; Seng, Julia S.

    2014-01-01

    BACKGROUND Oxytocin is a promising biomarker for psychiatric conditions arising from early relational trauma, childhood maltreatment, and attachment dysregulation, including posttraumatic stress and dissociative disorders. OBJECTIVE This exploratory pilot study examined plasma oxytocin as a biomarker for alterations in the attachment system. DESIGN We used a single group, repeated-measures design with 15 women. The protocol used a film clip previously validated as a provocation to the hypothalamic–pituitary–adrenal axis. RESULTS The repeated-measures ANOVA showed differences in oxytocin across the three time points. Correlations with oxytocin indicated that measures of dissociation and somatization correlated most strongly with higher levels of oxytocin measured during exposure to the film’s bonding scene and posttraumatic stress disorder correlated most strongly with lower levels at the film’s abandonment scene. Post hoc analyses revealed differences in oxytocin response related to psychopathology. CONCLUSION Replication studies should characterize participants on a range of psychiatric conditions associated with attachment dysregulation. PMID:23950541

  8. Fifteen years of experience with Integral-Leg-Prosthesis: Cohort study of artificial limb attachment system.

    PubMed

    Juhnke, Dora-Lisa; Beck, James P; Jeyapalina, Sujee; Aschoff, Horst H

    2015-01-01

    Integral-Leg-Prosthesis (ILP) is a comparatively new attachment system that allows direct skeletal docking of artificial limbs. Between January 1999 and December 2013, 69 patients with transfemoral amputation were fitted with ILPs by a single German surgeon. Device design iterations and surgical techniques evolved during these years. For the purposes of comparison, patients receiving the first two designs and procedure iterations were placed in group 1 and the patients fitted with the final design were placed in group 2. Infection rate and planned and unplanned surgical interventions were statistically compared using Fisher exact test. Data demonstrated that the high rate of stoma-associated infections seen in group 1 was dramatically reduced in group 2. Of the 39 patients with 42 implants in group 2, none had operative interventions secondary to infection. All group 2 patients remained infection-free without the use of antibiotics by following a simple but defined wound-hygiene protocol. We concluded that the final iteration of the osseointegrated intramedullary device with a low energy surface at the soft tissue and prosthesis interface allowed a biologically stable skin stoma that remained infection-free without chronic use of antibiotics. The reduction in the infection rate was attributed to the clinically based, empirically driven changes in design and surgical techniques.

  9. Nuclear reactor fuel assembly duct-tube-to-handling-socket attachment system

    DOEpatents

    Christiansen, David W.; Smith, Bob G.

    1982-01-01

    A reusable system for removably attaching the upper end 10of a nuclear reactor duct tube to the lower end 30 of a nuclear reactor fuel assembly handling socket. A transition ring 20, fixed to the duct tube's upper end 10, has an interior-threaded section 22 with a first locking hole segment 24. An adaptor ring 40, fixed to the handling socket's lower end 30 has an outside-threaded section 42 with a second locking hole segment 44. The inside 22 and outside 42 threaded sections match and can be joined so that the first 24 and second 44 locking hole segments can be aligned to form a locking hole. A locking ring 50, with a locking pin 52, slides over the adaptor ring 40 so that the locking pin 52 fits in the locking hole. A swage lock 60 or a cantilever finger lock 70 is formed from the locking cup collar 26 to fit in a matching groove 54 or 56 in the locking ring 50 to prevent the locking ring's locking pin 52 from backing out of the locking hole.

  10. Comparative study of the fluid viscosity in tarsal hairy attachment systems of flies and beetles.

    PubMed

    Peisker, Henrik; Heepe, Lars; Kovalev, Alexander E; Gorb, Stanislav N

    2014-10-06

    Wet adhesive systems of insects strongly rely for their function on the formation of capillary bridges with the substrate. Studies on the chemical composition and evaporation dynamics of tarsal secretions strongly suggest a difference in chemistry of secretion in beetles and flies, both possessing hairy attachment devices. This difference is assumed to influence the viscosity of the secretion. Here, we applied a microrheological technique, based on the immersion of nanometric beads in the collected tarsal footprints, to estimate secretion viscosity in a beetle (Coccinella septempunctata) and a fly (Calliphora vicina). Both species studied possess distinct differences in viscosity, the median of which was calculated as 21.8 and 10.9 mPa s, respectively. We further present an approximate theoretical model to calculate the contact formation time of spatula-like terminal contact elements using the viscosity data of the covering fluid. The estimated contact formation time is proportional to the tarsal secretion viscosity and to the square of the contact radius of the contact element.

  11. Living on the Edge: Parasite Prevalence Changes Dramatically across a Range Edge in an Invasive Gecko.

    PubMed

    Coates, Andrew; Barnett, Louise K; Hoskin, Conrad; Phillips, Ben L

    2017-02-01

    Species interactions can determine range limits, and parasitism is the most intimate of such interactions. Intriguingly, the very conditions on range edges likely change host-parasite dynamics in nontrivial ways. Range edges are often associated with clines in host density and with environmental transitions, both of which may affect parasite transmission. On advancing range edges, founder events and fitness/dispersal costs of parasitism may also cause parasites to be lost on range edges. Here we examine the prevalence of three species of parasite across the range edge of an invasive gecko, Hemidactylus frenatus, in northeastern Australia. The gecko's range edge spans the urban-woodland interface at the edge of urban areas. Across this edge, gecko abundance shows a steep decline, being lower in the woodland. Two parasite species (a mite and a pentastome) are coevolved with H. frenatus, and these species become less prevalent as the geckos become less abundant. A third species of parasite (another pentastome) is native to Australia and has no coevolutionary history with H. frenatus. This species became more prevalent as the geckos become less abundant. These dramatic shifts in parasitism (occurring over 3.5 km) confirm that host-parasite dynamics can vary substantially across the range edge of this gecko host.

  12. Direct evidence of phospholipids in gecko footprints and spatula-substrate contact interface detected using surface-sensitive spectroscopy.

    PubMed

    Hsu, Ping Yuan; Ge, Liehui; Li, Xiaopeng; Stark, Alyssa Y; Wesdemiotis, Chrys; Niewiarowski, Peter H; Dhinojwala, Ali

    2012-04-07

    Observers ranging from Aristotle to young children have long marvelled at the ability of geckos to cling to walls and ceilings. Detailed studies have revealed that geckos are 'sticky' without the use of glue or suction devices. Instead, a gecko's stickiness derives from van der Waals interactions between proteinaceous hairs called setae and substrate. Here, we present surprising evidence that although geckos do not use glue, a residue is transferred on surfaces as they walk-geckos leave footprints. Using matrix-free nano-assisted laser desorption-ionization mass spectrometry, we identified the residue as phospholipids with phosphocholine head groups. Moreover, interface-sensitive sum-frequency generation spectroscopy revealed predominantly hydrophobic methyl and methylene groups and the complete absence of water at the contact interface between a gecko toe pad and the substrate. The presence of lipids has never been considered in current models of gecko adhesion. Our analysis of gecko footprints and the toe pad-substrate interface has significant consequences for models of gecko adhesion and by extension, the design of synthetic mimics.

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

    PubMed

    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].

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

    PubMed Central

    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

    2015-01-01

    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] PMID:26246284

  15. Cell biology of adhesive setae in gecko lizards.

    PubMed

    Alibardi, Lorenzo

    2009-01-01

    Adhesive devices of digital pads of gecko lizards are formed by microscopic hair-like structures termed setae that derive from the interaction between the oberhautchen and the clear layer of the epidermis. The two layers form the shedding complex and permit skin shedding in lizards. Setae consist of a resistant but flexible corneous material largely made of keratin-associated beta-proteins (KA beta Ps, formerly called beta-keratins) of 8-22 kDa and of alpha-keratins of 45-60 kDa. In Gekko gecko, 19 sauropsid keratin-associated beta-proteins (sKAbetaPs) and at least two larger alpha-keratins are expressed in the setae. Some sKA beta Ps are rich in cysteine (111-114 amino acids), while others are rich in glycine (169-219 amino acids). In the entire genome of Anolis carolinensis 40 Ka beta Ps are present and participate in the formation of all types of scales, pad lamellae and claws. Nineteen sKA beta Ps comprise cysteine-rich 9.2-14.4 kDa proteins of 89-142 amino acids, and 19 are glycine-rich 16.5-22.0 kDa proteins containing 162-225 amino acids, and only two types of sKA beta Ps are cysteine- and glycine-poor proteins. Genes coding for these proteins contain an intron in the 5'-non-coding region, a typical characteristic of most sauropsid Ka beta Ps. Gecko KA beta Ps show a central amino acid region of high homology and a beta-pleated conformation that is likely responsible for the polymerization of Ka beta Ps into long and resistant filaments. The association of numerous filaments, probably over a framework of alpha-keratins, permits the formation of bundles of corneous material for the elongation of setae, which may be over 100 microm long. The terminals branching off each seta may derive from the organization of the cytoskeleton and from the mechanical separation of keratin bundles located at the terminal apex of setae.

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

    PubMed

    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.

  17. Attachment Disorganization.

    ERIC Educational Resources Information Center

    Solomon, Judith, Ed.; George, Carol, Ed.

    Disorganized attachment relationships were first formally identified on the basis of the anomalous behavior of some infants during laboratory separations and reunions with the parent. This book presents new research and theory on the topic of attachment disorganization, an area of investigation that is of increasing importance in the study of…

  18. Attachment Disorganization.

    ERIC Educational Resources Information Center

    Solomon, Judith, Ed.; George, Carol, Ed.

    Disorganized attachment relationships were first formally identified on the basis of the anomalous behavior of some infants during laboratory separations and reunions with the parent. This book presents new research and theory on the topic of attachment disorganization, an area of investigation that is of increasing importance in the study of…

  19. Finger-attachment device for the feedback of gripping and pulling force in a manipulating system for brain tumor resection.

    PubMed

    Chinbe, Hiroyuki; Yoneyama, Takeshi; Watanabe, Tetsuyou; Miyashita, Katsuyoshi; Nakada, Mitsutoshi

    2017-07-10

    Development and evaluation of an effective attachment device for a bilateral brain tumor resection robotic surgery system based on the sensory performance of the human index finger in order to precisely detect gripping- and pulling-force feedback. First, a basic test was conducted to investigate the performance of the human index finger in the gripping- and pulling-force feedback system. Based on the test result, a new finger-attachment device was designed and constructed. Then, discrimination tests were conducted to assess the pulling force and the feedback on the hardness of the gripped material. The results of the basic test show the application of pulling force on the side surface of the finger has an advantage to distinguish the pulling force when the gripping force is applied on the finger-touching surface. Based on this result, a finger-attachment device that applies a gripping force on the finger surface and pulling force on the side surface of the finger was developed. By conducting a discrimination test to assess the hardness of the gripped material, an operator can distinguish whether the gripped material is harder or softer than a normal brain tissue. This will help in confirming whether the gripped material is a tumor. By conducting a discrimination test to assess the pulling force, an operator can distinguish the pulling-force resistance when attempting to pull off the soft material. Pulling-force feedback may help avoid the breaking of blood pipes when they are trapped in the gripper or attached to the gripped tissue. The finger-attachment device that was developed for detecting gripping- and pulling-force feedback may play an important role in the development of future neurosurgery robotic systems for precise and safe resection of brain tumors.

  20. Strong, reversible underwater adhesion via gecko-inspired hydrophobic fibers.

    PubMed

    Soltannia, Babak; Sameoto, Dan

    2014-12-24

    Strong, reversible underwater adhesion using gecko-inspired surfaces is achievable through the use of a hydrophobic structural material and does not require surface modification or suction cup effects for this adhesion to be effective. Increased surface energy can aid in dry adhesion in an air environment but strongly degrades wet adhesion via reduction of interfacial energy underwater. A direct comparison of structurally identical but chemically different mushroom shaped fibers shows that strong, reversible adhesion, even in a fully wetted, stable state, is feasible underwater if the structural material of the fibers is hydrophobic and the mating surface is not strongly hydrophilic. The exact adhesion strength will be a function of the underwater interfacial energy between surfaces and the specific failure modes of individual fibers. This underwater adhesion has been calculated to be potentially greater than the dry adhesion for specific combinations of hydrophobic surfaces.

  1. Gecko inspired carbon nanotube based thermal gap pads

    NASA Astrophysics Data System (ADS)

    Sethi, Sunny; Dhinojwala, Ali

    2012-02-01

    Thermal management has become a critical factor in designing the next generation of microprocessors. The bottleneck in design of material for efficient heat transfer from electronic units to heat sinks is to enhance heat flow across interface between two dissimilar, rough surfaces. Carbon nanotubes (CNT) have been shown to be promising candidates for thermal transport. However, the heat transport across the interface continues to be a challenging hurdle. In the current work we designed free standing thermal pads based on gecko-inspired carbon nanotube adhesives. The pads were made of metallic carbon nanotubes and the structure was designed such that it would allow large area of intimate contact. We showed that these adhesive pads can be used as electrical and thermal interconnects.

  2. Redesign of solid rocket booster/external tank attachment ring for the space transportation system

    NASA Technical Reports Server (NTRS)

    Mccomb, Harvey G., Jr. (Compiler)

    1987-01-01

    An improved design concept is presented for the Space Shuttle solid rocket booster (SRB)/external tank (ET) attachment ring structural component. This component picks up three struts which attach the aft end of each SRB to the ET. The concept is a partial ring with carefully tapered ends to distribute fastener loads safely into the SRB. Extensive design studies and analyses were performed to arrive at the concept. Experiments on structural elements were performed to determine material strength and stiffness characteristics. Materials and fabrication studies were conducted to determine acceptable tolerances for the design concept. An overview is provided of the work along with conclusions and major recommendations.

  3. Water vapor permeability of the rigid-shelled gecko egg.

    PubMed

    Andrews, Robin M

    2012-07-01

    The vast majority of squamate reptiles (lizards and snakes) produce parchment-shelled eggs that absorb water during incubation, and thus increase in mass, volume, and surface area. In contrast, females from a single monophyletic lineage of gekkotan lizards produce rigid-shelled eggs. These eggs are functionally comparable to those of birds, that is, at oviposition, eggs contain all the water needed for development, and their mass decreases during incubation via the diffusion of water vapor through the shell. I determined patterns of water loss and shell permeability to water vapor from oviposition to hatching for the rigid-shelled eggs of the gekkonid Chrondrodactylus turneri and compared permeability of C. turneri eggs to those of birds and other squamates. Chrondrodactylus turneri eggs incubated at 28.5°C and 40% relative humidity (RH) decreased in mass by 14% over the course of a 68-day incubation period. The rate of water loss varied during incubation; egg mass decreased rapidly during the first 8 days of incubation, declined at a low constant rate during the next 35 days, and then decreased rapidly during the final 25 days of incubation. Overall permeability was 0.17 mg/day/kPa/cm(2) . Percent water loss of rigid-shelled gecko eggs during incubation is similar to that exhibited by birds, but water vapor permeability is about one-third that of bird eggs and several orders of magnitude lower than that of parchment-shelled squamate eggs. In general, the water economy of their eggs may be associated with the adaptive radiation of the rigid-shelled sphaerodactylid, phyllodactylid, and gekkonid geckos.

  4. Ceramic to metal attachment system. [Ceramic electrode to metal conductor in MHD generator

    DOEpatents

    Marchant, D.D.

    1983-06-10

    A composition and method are described for attaching a ceramic electrode to a metal conductor. A layer of randomly interlocked metal fibers saturated with polyimide resin is sandwiched between the ceramic electrode and the metal conductor. The polyimide resin is then polymerized providing bonding.

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

    PubMed Central

    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. PMID:26657838

  6. Extension of the CAPRAM mechanism with the improved mechanism generator GECKO-A

    NASA Astrophysics Data System (ADS)

    Bräuer, Peter; Mouchel-Vallon, Camille; Tilgner, Andreas; Wolke, Ralf; Aumont, Bernard; Herrmann, Hartmut

    2013-04-01

    Organic compounds are an ubiquitous constituent of the tropospheric multiphase system. With either biogenic or anthropogenic sources, they have a major influence on the atmospheric multiphase system and thus have become a main research topic within the last decades. Modelling can provide a useful tool to explore the tropospheric multiphase chemistry. While in the gas phase several comprehensive near-explicit mechanisms exist, in the aqueous phase those mechanisms are very limited. The current study aims to advance the currently most comprehensive aqueous phase mechanism CAPRAM 3.0 by means of automated mechanism construction. Therefore, the mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere; see Aumont et al., 2005) has been advanced to the aqueous phase. A protocol has been designed for automated mechanism construction based on reviewed experimental data and evaluated prediction methods. The generator is able to describe the oxidation of aliphatic organic compounds by OH and NO3. For the mechanism construction, mainly structure-activity relationships are used, which are completed by Evans-Polanyi-type correlations and further suitable estimates. GECKO-A has been used to create new CAPRAM versions, where branching ratios are introduced and new chemical subsystems with species with up to 4 carbon atoms are added. The currently most comprehensive version, CAPRAM 3.7, includes about 2000 aqueous phase species and more than 3300 reactions in the aqueous phase. Box model studies have been performed using a meteorological scenario with non-permanent clouds. Besides the investigation of the concentration-time profiles, detailed time-resolved flux analyses have been performed. Several aqueous phase subsystems have been investigated, such as the formation of oxidised mono- and diacids in the aqueous phase, as well as interactions to inorganic cycles and the influence on the gas phase chemistry and composition. Results

  7. Extension of the CAPRAM mechanism with the improved mechanism generator GECKO-A

    NASA Astrophysics Data System (ADS)

    Herrmann, H.; Bräuer, P.; Mouchel-Vallon, C.; Tilgner, A.; Wolke, R.; Aumont, B.

    2013-12-01

    The ubiquitous abundance of organic compounds in natural and anthropogenically influenced eco-systems has put these compounds into the focus of environmental research. To investigate the chemistry of organic compounds in the tropospheric multiphase system, modelling can provide a useful tool. While in the gas phase several comprehensive near-explicit mechanisms exist, in the aqueous phase those mechanisms are very limited. The present study aims to advance the currently most comprehensive aqueous phase mechanism CAPRAM 3.0n (Tilgner and Herrmann, 2010; Bräuer et al., 2013) by means of automated mechanism self-construction. Therefore, the mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere; see Aumont et al., 2005) has been advanced to the aqueous phase. A protocol has been designed for automated mechanism construction based on reviewed experimental data and evaluated prediction methods. The generator is able to describe the oxidation of aliphatic organic compounds by OH and NO3. For the mechanism construction, mainly structure-activity relationships are used. They are completed by Evans-Polanyi-type correlations, which have been further improved for the purpose of automated mechanism self-construction. GECKO-A has been used to create new CAPRAM versions, where branching ratios are introduced and new chemical subsystems with species with up to 4 carbon atoms are added. The currently most comprehensive version, CAPRAM 3.5alpha, includes about 2000 aqueous phase species and more than 3300 reactions in the aqueous phase. Process studies with the box model SPACCIM (SPectral Aerosol Cloud Chemistry Interaction Model; Wolke et al., 2005) have been performed using a meteorological scenario with non-permanent clouds. Besides the investigation of the concentration-time profiles, detailed time-resolved flux analyses have been performed. Several aqueous phase subsystems have been investigated, such as the formation of

  8. Diversity of microbial communities in an attached-growth system using Bauxsol™ pellets for wastewater treatment.

    PubMed

    Despland, Laure M; Vancov, Tony; Aragno, Michel; Clark, Malcolm W

    2012-09-01

    Columns of Bauxsol™ pellets were used in a field experiment as biomass support particle for wastewater microbial communities. The attached microbial community structure was analysed using denaturing gradient gel electrophoresis (DGGE), targeting the 16S rDNA gene's V3 region. DGGE profiles showed that the type and composition of support particles used (i.e. Bauxsol™ pellets or gravel) had a significant impact on the attached bacterial communities (64% dissimilarity). In addition, ecological indices revealed a more heterogeneous bacterial community structure on the Bauxsol™ pellets. TOC/TN ratios post-experiment (6.5-9.3) suggested a good level of biological activity (i.e. active biofilm) in the Bauxsol™ columns. Moreover, Bauxsol™ pellets were mostly made of inorganic carbon, suggesting insoluble carbonate biomineralisation. Polymerase chain reaction (PCR) amplification of specific marker genes (i.e. bacterial and archaeal amoA genes, nosZ gene, and hzo gene) were used to identify the presence of attached bacterial communities associated with nitrogen transformation. The results along with geochemical data (i.e. up to 50% nitrogen removal) revealed co-existence of ammonia-oxidising bacteria, denitrifiers, and anammox organisms. This study conclusively demonstrates that microbial communities are well-adapted to Bauxsol™ pellets and bacterial communities involved in the nitrogen cycle are present. Copyright © 2012 Elsevier B.V. All rights reserved.

  9. Slippery pores: anti-adhesive effect of nanoporous substrates on the beetle attachment system

    PubMed Central

    Gorb, E. V.; Hosoda, N.; Miksch, C.; Gorb, S. N.

    2010-01-01

    Traction experiments with adult seven-spotted ladybird beetles Coccinella septempunctata (L.) were carried out to study the influence of surface structure on insect attachment. Force measurements were performed with tethered walking insects, both males and females, on five different substrates: (i) smooth glass plate, (ii) smooth solid Al2O3 (sapphire) disc, and (iii–v) porous Al2O3 discs (anodisc membranes) with the same pore diameter but different porosity. The traction force of beetles ranged from 0.16 to 16.59 mN in males and from 0.32 to 8.99 mN in females. In both sexes, the highest force values were obtained on smooth solid surfaces, where males showed higher forces than females. On all three porous substrates, forces were significantly reduced in both males and females, and the only difference within these surfaces was obtained between membranes with the highest and lowest porosity. Males produced essentially lower forces than females on porous samples. The reduction in insect attachment on anodisc membranes may be explained by (i) possible absorption of the secretion fluid from insect adhesive pads by porous media and/or (ii) the effect of surface roughness. Differences in attachment between males and females were probably caused by the sexual dimorphism in the terminal structure of adhesive setae. PMID:20427333

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

    PubMed Central

    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

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

    PubMed

    Ceríaco, Luis M P; Marques, Mariana P; Madeira, Natália C; Vila-Viçosa, Carlos M; Mendes, Paula

    2011-09-05

    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.

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

    PubMed

    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.

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

    PubMed

    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.

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

    USGS Publications Warehouse

    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.

  15. Shear adhesion strength of thermoplastic gecko-inspired synthetic adhesive exceeds material limits.

    PubMed

    Gillies, Andrew G; Fearing, Ronald S

    2011-09-20

    Natural gecko array wearless dynamic friction has recently been reported for 30,000 cycles on a smooth substrate. Following these findings, stiff polymer gecko-inspired synthetic adhesives have been proposed for high-cycle applications such as robot feet. Here we examine the behavior of high-density polyethylene (HDPE) and polypropylene (PP) microfiber arrays during repeated cycles of engagement on a glass surface, with a normal preload of less than 40 kPa. We find that fiber arrays maintained 54% of the original shear stress of 300 kPa after 10,000 cycles, despite showing a marked plastic deformation of fiber tips. This deformation could be due to shear-induced plastic creep of the fiber tips from high adhesion forces, adhesive wear, or thermal effects. We hypothesize that a fundamental material limit has been reached for these fiber arrays and that future gecko synthetic adhesive designs must take into account the high adhesive forces generated to avoid damage. Although the synthetic material and natural gecko arrays have a similar elastic modulus, the synthetic material does not show the same wear-free dynamic friction as the gecko. © 2011 American Chemical Society

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27071837

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

    PubMed

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

    2016-04-13

    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.

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

    PubMed

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

    PubMed

    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 < 0.05) between the two groups for mean body 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.

  1. Late-life attachment.

    PubMed

    Freitas, Mélanie; Rahioui, Hassan

    2017-03-01

    Old age is likely to cause a crisis in one's life because of the vulnerabilities it brings up, acting as stressful elements disrupting the elder's feeling of security. It leads to the activation of what is called his attachment system, consisting in attachment styles and interpersonal emotional regulation strategies. To recover a higher sense of safety, the elder would refer to his attachment figures, that is to say closed people paying attention to him, showing towards him availability and consideration. However older adults particularly see their tolerance threshold lowered, regarding an accumulation of losses (true or symbolic) and stressful events within their lifetime. In a psychological and organic exhaustion phenomenon, the risk is to wear out the interpersonal emotional regulation strategies. These are as much vulnerabilities that may increase psychiatric decompensation, including depression. To resolve the tension of this period and to found a necessary secure feeling, the elder will have to redesign the attachment links previously settled and proceed to adjustments to this new context. The need of relational closeness comes back in the elders' attachment behaviour, counting on attachment figures not only to help their loneliness or dependency, but essentially to support them in a narcissist and affective way. That is why attachment theory enlightens the late life period, such as the new challenges older adults have to face. Many studies recognize its value in understanding the transition to old age, but without proposing conceptualization. We aim first to focus on attachment conception to say how much it is relevant with elderly, and then to describe specific terms of attachment within this population in order to better understand those patients. To finish, we must think about new therapeutic proposals taking into consideration the attachment perspective for a better understanding of old age transition.

  2. The neurobiology of attachment.

    PubMed

    Insel, T R; Young, L J

    2001-02-01

    It is difficult to think of any behavioural process that is more intrinsically important to us than attachment. Feeding, sleeping and locomotion are all necessary for survival, but humans are, as Baruch Spinoza famously noted, "a social animal" and it is our social attachments that we live for. Over the past decade, studies in a range of vertebrates, including humans, have begun to address the neural basis of attachment at a molecular, cellular and systems level. This review describes some of the important insights from this work.

  3. Development of a rotating algal biofilm growth system for attached microalgae growth with in situ biomass harvest.

    PubMed

    Gross, Martin; Henry, Wesley; Michael, Clayton; Wen, Zhiyou

    2013-12-01

    This work aimed to develop a rotating algal biofilm (RAB) cultivation system that can be widely adopted by microalgae producers for easy biomass harvest. Algal cells were grown on the surface of a material rotating between nutrient-rich liquid and CO2-rich gaseous phase. Scrapping biomass from the attached surface avoided the expensive harvest operations such as centrifugation. Among various attachment materials, cotton sheet resulted in best algal growth, durability, and cost effectiveness. A lab-scale RAB system was further optimized with harvest frequency, rotation speed, and CO2 levels. The algal biomass from the RAB system had a similar water content as that in centrifuged biomass. An open pond raceway retrofitted with a pilot-scale RAB system resulted in a much higher biomass productivity when compared to a control open pond. Collectively, the research shows that the RAB system is an efficient algal culture system for easy biomass harvest with enhanced biomass productivity. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Material Evaluation of an Elastomer, Epoxy and Lightweight Concrete Rail Attachment System for Direct Fixation Light Rail Applications

    NASA Astrophysics Data System (ADS)

    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.

  5. Evaluation of Underwater Adhesives and Friction Coatings for In Situ Attachment of Fiber Optic Sensor System for Subsea Applications

    NASA Technical Reports Server (NTRS)

    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

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  9. The unique lipid composition of gecko (Gekko Gekko) photoreceptor outer segment membranes.

    PubMed

    Yuan, C; Chen, H; Anderson, R E; Kuwata, O; Ebrey, T G

    1998-08-01

    This study investigated the lipid and fatty acid composition of gecko photoreceptor outer segment membranes which contain the P521 cone-type pigment. The lipids of gecko photoreceptor outer segment membranes were first extracted and separated by thin layer chromatography (TLC) and then analyzed by gas chromatography (GC). Our results show that gecko photoreceptor outer segment membranes contain less phosphatidylethanolamine (PE) and more phosphatidylcholine (PC) and phosphatidylserine (PS) compared with those of bovine and frog. The content of the polyunsaturated fatty acid, docosahexaenoic acid (DHA), in PC and PS is also the highest yet reported (55 and 63%, respectively). These lipid differences may provide some insight into the specific lipid requirements of cone-type pigments.

  10. Dynamic stabilization of a bistable suspension system attached to a flexible host structure for operational safety enhancement

    NASA Astrophysics Data System (ADS)

    Yang, Kai; Harne, R. L.; Wang, K. W.; Huang, Hai

    2014-12-01

    In engineering applications, a suspension system may be attached to a flexible host structure, e.g. spacecraft truss, to provide vibration isolation for sensitive instrumentation, where the suspension and host structure dynamics are strongly coupled. For linear suspensions, a resonance normally occurs adjacent to the roll-off frequency band, which significantly and detrimentally amplifies vibration transmission. To avoid the adverse resonance for operational safety enhancement, this research proposes a nonlinear bistable suspension and evaluates its performance when attached to a flexible host structure. Dynamic models of the bistable and comparable linear suspensions attached to the host structure are formulated, and steady-state responses are predicted using analytical and numerical methods. Results show that the bistable suspension can eliminate the harmful resonance via a dynamic stabilization phenomenon, and simultaneously retains the favorable isolation performance in the roll-off bandwidth as compared to the linear suspension. Series of experimental investigations support the analytical and numerical findings and help define design guidelines for operational safety improvement.

  11. The effect of contaminants on the adhesion of the spatulae of a gecko.

    PubMed

    Jeng, Yeau-Ren; Mao, Chien-Ping

    2010-12-01

    Many researchers have reported that the robust adhesion that enables geckos to move quickly and securely across a range of vertical and horizontal surfaces is provided by the hierarchical structure of their feet (i.e. lamellae, setae, spatulae, etc.). Maintaining this robust adhesion requires an intimate contact between the terminal tips of the spatulae and the surface. The aim of this study was to investigate the effect on the adhesive properties of the spatulae when a particle becomes trapped at the contact surface. Using the Johnson, Kendall and Roberts (JKR) theory, a model was constructed to assist in the analysis of the interactions between the spatula tip, the particle and the surface. The results showed that the keratin (the natural material of the spatula) provides a robust system for adhesion even when there is a particle in the contact area, and the effective contact area of spatulae will be 80%. When the particle is significantly harder than the surface, the adhesion properties of the contact surface influenced by the particle will be more obvious. The results also reveal that the generated adhesion is considerably higher when the spatula is in contact with a softer surface, such as wood or concrete, rather than a hard surface, such as glass or SiO2.

  12. Effect of incubation temperature and androgens on dopaminergic activity in the leopard gecko, Eublepharis macularius.

    PubMed

    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.

  13. Rate-dependent frictional adhesion in natural and synthetic gecko setae

    PubMed Central

    Gravish, Nick; Wilkinson, Matt; Sponberg, Simon; Parness, Aaron; Esparza, Noe; Soto, Daniel; Yamaguchi, Tetsuo; Broide, Michael; Cutkosky, Mark; Creton, Costantino; Autumn, Kellar

    2010-01-01

    Geckos owe their remarkable stickiness to millions of dry, hard setae on their toes. In this study, we discovered that gecko setae stick more strongly the faster they slide, and do not wear out after 30 000 cycles. This is surprising because friction between dry, hard, macroscopic materials typically decreases at the onset of sliding, and as velocity increases, friction continues to decrease because of a reduction in the number of interfacial contacts, due in part to wear. Gecko setae did not exhibit the decrease in adhesion or friction characteristic of a transition from static to kinetic contact mechanics. Instead, friction and adhesion forces increased at the onset of sliding and continued to increase with shear speed from 500 nm s−1 to 158 mm s−1. To explain how apparently fluid-like, wear-free dynamic friction and adhesion occur macroscopically in a dry, hard solid, we proposed a model based on a population of nanoscopic stick–slip events. In the model, contact elements are either in static contact or in the process of slipping to a new static contact. If stick–slip events are uncorrelated, the model further predicted that contact forces should increase to a critical velocity (V*) and then decrease at velocities greater than V*. We hypothesized that, like natural gecko setae, but unlike any conventional adhesive, gecko-like synthetic adhesives (GSAs) could adhere while sliding. To test the generality of our results and the validity of our model, we fabricated a GSA using a hard silicone polymer. While sliding, the GSA exhibited steady-state adhesion and velocity dependence similar to that of gecko setae. Observations at the interface indicated that macroscopically smooth sliding of the GSA emerged from randomly occurring stick–slip events in the population of flexible fibrils, confirming our model predictions. PMID:19493896

  14. Rate-dependent frictional adhesion in natural and synthetic gecko setae.

    PubMed

    Gravish, Nick; Wilkinson, Matt; Sponberg, Simon; Parness, Aaron; Esparza, Noe; Soto, Daniel; Yamaguchi, Tetsuo; Broide, Michael; Cutkosky, Mark; Creton, Costantino; Autumn, Kellar

    2010-02-06

    Geckos owe their remarkable stickiness to millions of dry, hard setae on their toes. In this study, we discovered that gecko setae stick more strongly the faster they slide, and do not wear out after 30,000 cycles. This is surprising because friction between dry, hard, macroscopic materials typically decreases at the onset of sliding, and as velocity increases, friction continues to decrease because of a reduction in the number of interfacial contacts, due in part to wear. Gecko setae did not exhibit the decrease in adhesion or friction characteristic of a transition from static to kinetic contact mechanics. Instead, friction and adhesion forces increased at the onset of sliding and continued to increase with shear speed from 500 nm s(-1) to 158 mm s(-1). To explain how apparently fluid-like, wear-free dynamic friction and adhesion occur macroscopically in a dry, hard solid, we proposed a model based on a population of nanoscopic stick-slip events. In the model, contact elements are either in static contact or in the process of slipping to a new static contact. If stick-slip events are uncorrelated, the model further predicted that contact forces should increase to a critical velocity (V*) and then decrease at velocities greater than V*. We hypothesized that, like natural gecko setae, but unlike any conventional adhesive, gecko-like synthetic adhesives (GSAs) could adhere while sliding. To test the generality of our results and the validity of our model, we fabricated a GSA using a hard silicone polymer. While sliding, the GSA exhibited steady-state adhesion and velocity dependence similar to that of gecko setae. Observations at the interface indicated that macroscopically smooth sliding of the GSA emerged from randomly occurring stick-slip events in the population of flexible fibrils, confirming our model predictions.

  15. A Jungian contribution to a dynamic systems understanding of disorganized attachment.

    PubMed

    Carter, Linda

    2011-06-01

    This panel emerged from shared clinical concerns when working with adult patients whose presentation style was reminiscent of a disorganized (Type D) infant attachment pattern. Psychotherapeutic work with such patients poses complicated transference and countertransference dilemmas which are addressed by all four panellists via theory and clinical vignettes. In common is an interest in contemporary attachment, neuroscience and trauma theories and their relationship to analytical psychology. Intergenerational trauma seems to be a salient factor in the evolution of fragmented and fragmenting interactions that lead to failures in self-coherence and healthy interpersonal relationships. Such early relational trauma is compounded by further episodes of abuse and neglect leading to failure in a core sense of self. These clinicians share how they have integrated theory and practice in order to help dissociated and disorganized patients to transform their dark and extraordinary suffering through implicit and explicit experiences with the analyst into new, life giving patterns of relationship with self and others. The alchemy of transformation, both positive and negative, is evident in the case material presented.

  16. Why have not the hairs on the feet of gecko been smaller?

    NASA Astrophysics Data System (ADS)

    Su, Yewang; He, Shijie; Hwang, Keh-Chih; Ji, Baohua

    2012-10-01

    The nanometer size of the tiny hair is the key to the secret of strong stickiness of gecko's feet, by which the hair can achieve the maximum adhesion strength that is insensitive to the interfacial flaws with substrate surface. But the question why the hairs have not been smaller is not answered yet. In this study, we derived a geometric parameter of the surface structures considering lateral interaction among hairs, which gives a critical size below which these hairs will bunch together and cause failure of the adhesion, suggesting a lower limit of the dimension of hairs on gecko's feet.

  17. Vertical anisotropic microfibers for a gecko-inspired adhesive.

    PubMed

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

    2012-06-12

    Geckos are able to adhere strongly and release easily from surfaces because the structurally anisotropic fibers on their toes naturally exhibit force anisotropy based on the direction of articulation. Here, semicircular fibers, with varying amounts of contact area on the two faces, are investigated to ascertain whether fiber shape can be used to gain anisotropy in shear and shear adhesion forces. Testing of 10-μm-diameter polydimethylsiloxane (PDMS) fibers against a 4-mm-diameter flat glass puck show that shear and shear adhesion forces were two to five times greater when in-plane movement caused the flat face, rather than the curved face, of the fiber to come in contact with the glass puck. The directional adhesion and shear force anisotropy results are close to theoretical approximations using the Kendall peel model and clearly demonstrate how fiber shape may be used to influence the properties of the adhesive. This result has broad applicability, and by combining the results shown here with other current vertical and angled designs, synthetic adhesives can be further improved to behave more like their natural counterparts.

  18. Diversity of functional microornamentation in slithering geckos Lialis (Pygopodidae).

    PubMed

    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.

  19. Diversity of functional microornamentation in slithering geckos Lialis (Pygopodidae)

    PubMed Central

    Spinner, M.; Gorb, S. N.; Westhoff, G.

    2013-01-01

    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. PMID:24107533

  20. Gecko-inspired bidirectional double-sided adhesives.

    PubMed

    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.

  1. The oxytocin system promotes resilience to the effects of neonatal isolation on adult social attachment in female prairie voles.

    PubMed

    Barrett, C E; Arambula, S E; Young, L J

    2015-07-21

    Genes and social experiences interact to create variation in social behavior and vulnerability to develop disorders of the social domain. Socially monogamous prairie voles display remarkable diversity in neuropeptide receptor systems and social behavior. Here, we examine the interaction of early-life adversity and brain oxytocin receptor (OTR) density on adult social attachment in female prairie voles. First, pups were isolated for 3 h per day, or unmanipulated, from postnatal day 1-14. Adult subjects were tested on the partner preference (PP) test to assess social attachment and OTR density in the brain was quantified. Neonatal social isolation impaired female PP formation, without affecting OTR density. Accumbal OTR density was, however, positively correlated with the percent of time spent huddling with the partner in neonatally isolated females. Females with high accumbal OTR binding were resilient to neonatal isolation. These results are consistent with the hypothesis that parental nurturing shapes neural systems underlying social relationships by enhancing striatal OTR signaling. Thus, we next determined whether early touch, mimicking parental licking and grooming, stimulates hypothalamic OT neuron activity. Tactile stimulation induced immediate-early gene activity in OT neurons in neonates. Finally, we investigated whether pharmacologically potentiating OT release using a melanocortin 3/4 agonist, melanotan-II (10 mg kg(-1) subcutaneously), would mitigate the social isolation-induced impairments in attachment behavior. Neonatal melanotan-II administration buffered against the effects of early isolation on partner preference formation. Thus, variation in accumbal OTR density and early OT release induced by parental nurturing may moderate susceptibility to early adverse experiences, including neglect.

  2. The oxytocin system promotes resilience to the effects of neonatal isolation on adult social attachment in female prairie voles

    PubMed Central

    Barrett, C E; Arambula, S E; Young, L J

    2015-01-01

    Genes and social experiences interact to create variation in social behavior and vulnerability to develop disorders of the social domain. Socially monogamous prairie voles display remarkable diversity in neuropeptide receptor systems and social behavior. Here, we examine the interaction of early-life adversity and brain oxytocin receptor (OTR) density on adult social attachment in female prairie voles. First, pups were isolated for 3 h per day, or unmanipulated, from postnatal day 1–14. Adult subjects were tested on the partner preference (PP) test to assess social attachment and OTR density in the brain was quantified. Neonatal social isolation impaired female PP formation, without affecting OTR density. Accumbal OTR density was, however, positively correlated with the percent of time spent huddling with the partner in neonatally isolated females. Females with high accumbal OTR binding were resilient to neonatal isolation. These results are consistent with the hypothesis that parental nurturing shapes neural systems underlying social relationships by enhancing striatal OTR signaling. Thus, we next determined whether early touch, mimicking parental licking and grooming, stimulates hypothalamic OT neuron activity. Tactile stimulation induced immediate-early gene activity in OT neurons in neonates. Finally, we investigated whether pharmacologically potentiating OT release using a melanocortin 3/4 agonist, melanotan-II (10 mg kg−1 subcutaneously), would mitigate the social isolation-induced impairments in attachment behavior. Neonatal melanotan-II administration buffered against the effects of early isolation on partner preference formation. Thus, variation in accumbal OTR density and early OT release induced by parental nurturing may moderate susceptibility to early adverse experiences, including neglect. PMID:26196439

  3. Conflicts between motivational systems related to attachment trauma: Key to understanding the intra-family relationship between abused children and their abusers.

    PubMed

    Liotti, Giovanni

    2017-01-01

    Research on disorganization of infant attachment provides evidence that it can be caused not only by violent aggression or very early sexual abuse, but also by covert maltreating behavior, which includes the abdication of the caregiver's responsibility to soothe the infant's distress. This paper argues that both overtly abusive caregivers and merely "abdicating" caregivers may cause disorganization of infant attachment through a simultaneous and conflicting activation of the motivational systems governing attachment and survival defense in the infant. Other inborn motivational systems-regulating caretaking, competitiveness, and sexuality-are disorderly activated, during personality development, within the intra-family relationships of children whose infant attachment has been disorganized. The paper argues that conflicts and abnormal tensions between different motivational systems explain some paradoxical features of the interactions between abusers and abused, and allow for a better understanding of the interpersonal processes involved in the surfacing and exacerbation of dissociative symptoms in the abused.

  4. 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.

    PubMed

    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.

  5. Structural preferential attachment: Stochastic process for the growth of scale-free, modular, and self-similar systems

    NASA Astrophysics Data System (ADS)

    Hébert-Dufresne, Laurent; Allard, Antoine; Marceau, Vincent; Noël, Pierre-André; Dubé, Louis J.

    2012-02-01

    Many complex systems have been shown to share universal properties of organization, such as scale independence, modularity, and self-similarity. We borrow tools from statistical physics in order to study structural preferential attachment (SPA), a recently proposed growth principle for the emergence of the aforementioned properties. We study the corresponding stochastic process in terms of its time evolution, its asymptotic behavior, and the scaling properties of its statistical steady state. Moreover, approximations are introduced to facilitate the modeling of real systems, mainly complex networks, using SPA. Finally, we investigate a particular behavior observed in the stochastic process, the peloton dynamics, and show how it predicts some features of real growing systems using prose samples as an example.

  6. Design and performance of a compact Li+ ion attachment mass spectrometry system with an atmospheric sampling device.

    PubMed

    Takahashi, Seiji; Nakamura, Megumi; Fujii, Toshihiro

    2012-03-01

    This report describes the development of a compact ion attachment mass spectrometry system. A single turbomolecular pump was employed to fill the basic requirements for vacuum conditions simply and cost-effectively, without the need for a differential pumping stage. A Li(+) ion source was placed in the first of two vacuum chambers; a 0.4 mm aperture allowed the product ions to enter the second chamber for mass analysis. With the present system, any chemical species, including radical intermediates, can be detected at atmospheric pressure in real-time. The minimum detectable amount (at S/N = 3) of toluene was around 1.3 × 10(-12) g/s with a linearity greater than 10(4). For illustrative purposes, we tested the system on laboratory air and on aroma compounds in the headspace of the Yuzu plant, Citrus junos.

  7. Design and Performance of a Compact Li+ Ion Attachment Mass Spectrometry System with an Atmospheric Sampling Device

    NASA Astrophysics Data System (ADS)

    Takahashi, Seiji; Nakamura, Megumi; Fujii, Toshihiro

    2012-03-01

    This report describes the development of a compact ion attachment mass spectrometry system. A single turbomolecular pump was employed to fill the basic requirements for vacuum conditions simply and cost-effectively, without the need for a differential pumping stage. A Li+ ion source was placed in the first of two vacuum chambers; a 0.4 mm aperture allowed the product ions to enter the second chamber for mass analysis. With the present system, any chemical species, including radical intermediates, can be detected at atmospheric pressure in real-time. The minimum detectable amount (at S/ N = 3) of toluene was around 1.3 × 10-12 g/s with a linearity greater than 104. For illustrative purposes, we tested the system on laboratory air and on aroma compounds in the headspace of the Yuzu plant, Citrus junos.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

    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

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  12. A detailed 3D finite element analysis of the peeling behaviour of a gecko spatula.

    PubMed

    Sauer, Roger A; Holl, Matthias

    2013-01-01

    This paper presents a detailed finite element analysis of the adhesion of a gecko spatula. The gecko spatulae form the tips of the gecko foot hairs that transfer the adhesional and frictional forces between substrate and foot. The analysis is based on a parameterised description of the 3D geometry of the spatula that only requires 12 parameters. The adhesion is described by a nonlinear computational contact formulation that accounts for the van der Waals interaction between spatula and substrate. The spatula adhesion model is implemented using an enriched contact finite element formulation recently developed by the first author. The finite element model is then used to simulate the peeling behaviour of the gecko spatula under applied vertical and rotational loading for various model parameters. Variations of the material stiffness, adhesional strength and range, stiction, spatula size and spatula inclination are considered to account for the natural variation of spatula properties. The study demonstrates that the spatula can function over a wide range of conditions. The computed pull-off forces are in agreement with experimental results reported in the literature. The study also examines the energy required for the spatula pull-off. The proposed model is ideal to study the influence of substrate roughness on the spatula adhesion, as is finally demonstrated.

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

    PubMed

    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.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    Peng, Zhilong; Yang, Yazheng; Chen, Shaohua

    2017-08-01

    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.

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

    Treesearch

    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...

  17. An Attachable Electromagnetic Energy Harvester Driven Wireless Sensing System Demonstrating Milling-Processes and Cutter-Wear/Breakage-Condition Monitoring

    PubMed Central

    Chung, Tien-Kan; Yeh, Po-Chen; Lee, Hao; Lin, Cheng-Mao; Tseng, Chia-Yung; Lo, Wen-Tuan; Wang, Chieh-Min; Wang, Wen-Chin; Tu, Chi-Jen; Tasi, Pei-Yuan; Chang, Jui-Wen

    2016-01-01

    An attachable electromagnetic-energy-harvester driven wireless vibration-sensing system for monitoring milling-processes and cutter-wear/breakage-conditions is demonstrated. The system includes an electromagnetic energy harvester, three single-axis Micro Electro-Mechanical Systems (MEMS) accelerometers, a wireless chip module, and corresponding circuits. The harvester consisting of magnets with a coil uses electromagnetic induction to harness mechanical energy produced by the rotating spindle in milling processes and consequently convert the harnessed energy to electrical output. The electrical output is rectified by the rectification circuit to power the accelerometers and wireless chip module. The harvester, circuits, accelerometer, and wireless chip are integrated as an energy-harvester driven wireless vibration-sensing system. Therefore, this completes a self-powered wireless vibration sensing system. For system testing, a numerical-controlled machining tool with various milling processes is used. According to the test results, the system is fully self-powered and able to successfully sense vibration in the milling processes. Furthermore, by analyzing the vibration signals (i.e., through analyzing the electrical outputs of the accelerometers), criteria are successfully established for the system for real-time accurate simulations of the milling-processes and cutter-conditions (such as cutter-wear conditions and cutter-breaking occurrence). Due to these results, our approach can be applied to most milling and other machining machines in factories to realize more smart machining technologies. PMID:26907297

  18. An Attachable Electromagnetic Energy Harvester Driven Wireless Sensing System Demonstrating Milling-Processes and Cutter-Wear/Breakage-Condition Monitoring.

    PubMed

    Chung, Tien-Kan; Yeh, Po-Chen; Lee, Hao; Lin, Cheng-Mao; Tseng, Chia-Yung; Lo, Wen-Tuan; Wang, Chieh-Min; Wang, Wen-Chin; Tu, Chi-Jen; Tasi, Pei-Yuan; Chang, Jui-Wen

    2016-02-23

    An attachable electromagnetic-energy-harvester driven wireless vibration-sensing system for monitoring milling-processes and cutter-wear/breakage-conditions is demonstrated. The system includes an electromagnetic energy harvester, three single-axis Micro Electro-Mechanical Systems (MEMS) accelerometers, a wireless chip module, and corresponding circuits. The harvester consisting of magnets with a coil uses electromagnetic induction to harness mechanical energy produced by the rotating spindle in milling processes and consequently convert the harnessed energy to electrical output. The electrical output is rectified by the rectification circuit to power the accelerometers and wireless chip module. The harvester, circuits, accelerometer, and wireless chip are integrated as an energy-harvester driven wireless vibration-sensing system. Therefore, this completes a self-powered wireless vibration sensing system. For system testing, a numerical-controlled machining tool with various milling processes is used. According to the test results, the system is fully self-powered and able to successfully sense vibration in the milling processes. Furthermore, by analyzing the vibration signals (i.e., through analyzing the electrical outputs of the accelerometers), criteria are successfully established for the system for real-time accurate simulations of the milling-processes and cutter-conditions (such as cutter-wear conditions and cutter-breaking occurrence). Due to these results, our approach can be applied to most milling and other machining machines in factories to realize more smart machining technologies.

  19. Attachment Apparatus

    SciTech Connect

    Morrison, Edward F.

    1998-08-18

    The present invention includes an attachment apparatus comprising a rotation limiting member adapted to be threaded onto a threaded member; and a preload nut adapted to be threaded onto the threaded member. The rotation limiting member comprises a plurality of pins; and the preload nut comprises plurality of slots, preferably wherein the plurality of pins and the plurality of slots are the same in number, which is preferably three. The plurality of pins of the rotation limiting member are filled into a corresponding plurality of slots of the preload nut to form a rotatable unit adapted to be threaded onto the threaded member. In use, the rotatable unit is threaded onto the threaded member. The present invention thus provides a unitized removable device for holes, including holes other than circular in shape, which have an established depth before an end of, or before an enlargement of the hole. The configuration of some exposed part of the device, or the head, is shaped and formed for its intended purpose, such as clamping, anchor points, eye bolts, stud anchor, and the like. The device allows for the installation, preloading and removal of all components of the device, as a unit, without damage to the member for which attachment is required by simple rotations of some exposed part of the device.

  20. Comparative evaluation of three attached growth systems and a constructed wetland for in situ treatment of raw municipal wastewater.

    PubMed

    Loupasaki, E; Diamadopoulos, E

    2013-01-01

    The necessity to treat municipal wastewaters in situ, with a low cost, yet effective system, led to the research of alternative methods for wastewater treatment. Attached growth systems can be an alternative option. Three attached growth systems with different media substrate, a rockwool cubes unit, a Kaldnes rings unit and a plastic bottle caps unit were studied in comparison with a constructed wetland in order to evaluate their ability to treat raw municipal wastewater. The selection of the three different media was based on their high porosity and surface area, as well as their availability and price. Three different operating periods were carried out with variations in the organic loading rate and the feeding frequency. The units were fed intermittently with short resting periods, less than 32 h, and relative high mean organic loading rates of 70, 50 and 30 g chemical oxygen demand (COD)/(m2d), respectively for each operating period. The constructed wetland and the rockwool cubes unit were the most effective, with mean COD reduction as mass rate (mg/d) 88% and 88%, biological oxygen demand 78% and 76%, dissolved organic carbon 73% and 67%, and total suspended solids 91% and 92%, respectively. Total nitrogen reduction was significantly higher at the constructed wetland with mean reduction as mass rate 51%, 60% and 83% for each period, compared to 41%, 43% and 60%, respectively, of the rockwool cubes unit. This study showed that it is possible to design, build and operate in situ small and decentralized treatment systems by using readily available packing materials and with minimum wastewater pretreatment.

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

    PubMed

    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.

  2. Removal Time and Efficacy of Riddell Quick Release Face Guard Attachment System Side Clips During 1 Football Season

    PubMed Central

    Gruppen, Tonia; Smith, Molly; Ganss, Andrea

    2012-01-01

    Context In the National Athletic Trainers' Association position statement, “Acute Management of the Cervical Spine-Injured Athlete,” the technique recommended for face-mask (FM) removal is one that “creates the least head and neck motion, is performed most quickly, is the least difficult, and carries the least chance of failure.” Industrial and technological advances in football helmet design and FM attachment systems might influence the efficacy of emergency FM removal. Objective To examine the removal times and success rates of the Quick Release (QR) Face Guard Attachment System (Riddell Sports, Inc, Elyria, OH) throughout and at the conclusion of 1 season of play by a National Collegiate Athletic Association Division III football team competing in the Midwest. Design Controlled laboratory study. Setting College laboratory. Patients or Other Participants A total of 69 randomly selected Revolution IQ (Riddell Sports, Inc) football helmets fitted with the QR system were used. Intervention(s) Each helmet was secured to a spine board, and investigators attempted to remove both of the QR side clips from the helmet with the Riddell insertion tool. Main Outcome Measure(s) Dependent variables included total time for removal of both QR side clips from the FM and success rate for removal of both side clips. Results The overall success rate for removal of both clips was 94.8% (164/173), whereas the mean times for removal of both clips ranged from 9.92 ± 12.06 seconds to 16.65 ± 20.97 seconds over 4 trial sessions. We found no differences among mean times for trial sessions throughout the season of play among the same helmets or among different helmets (P > .05). Conclusions Removal time and success rate of the Riddell QR were satisfactory during and after 1 season of play despite use in various temperatures and precipitation. PMID:22889658

  3. Removal time and efficacy of Riddell Quick Release Face Guard Attachment System side clips during 1 football season.

    PubMed

    Gruppen, Tonia; Smith, Molly; Ganss, Andrea

    2012-01-01

    In the National Athletic Trainers' Association position statement, "Acute Management of the Cervical Spine-Injured Athlete," the technique recommended for face-mask (FM) removal is one that "creates the least head and neck motion, is performed most quickly, is the least difficult, and carries the least chance of failure." Industrial and technological advances in football helmet design and FM attachment systems might influence the efficacy of emergency FM removal. To examine the removal times and success rates of the Quick Release (QR) Face Guard Attachment System (Riddell Sports, Inc, Elyria, OH) throughout and at the conclusion of 1 season of play by a National Collegiate Athletic Association Division III football team competing in the Midwest. Controlled laboratory study. College laboratory. A total of 69 randomly selected Revolution IQ (Riddell Sports, Inc) football helmets fitted with the QR system were used. Each helmet was secured to a spine board, and investigators attempted to remove both of the QR side clips from the helmet with the Riddell insertion tool. Dependent variables included total time for removal of both QR side clips from the FM and success rate for removal of both side clips. The overall success rate for removal of both clips was 94.8% (164/173), whereas the mean times for removal of both clips ranged from 9.92 ± 12.06 seconds to 16.65 ± 20.97 seconds over 4 trial sessions. We found no differences among mean times for trial sessions throughout the season of play among the same helmets or among different helmets (P > .05). Removal time and success rate of the Riddell QR were satisfactory during and after 1 season of play despite use in various temperatures and precipitation.

  4. Integrating Recovery and the Narrative Attachment Systems Perspective to Working through Borderline Personality Disorder

    ERIC Educational Resources Information Center

    Bernardon, Stephanie; Pernice-Duca, Francesca

    2012-01-01

    Borderline personality disorder (BPD) presents a number of symptoms and adjustment issues for individuals, but it is also associated with a myriad of risks for the larger family system. A systemic perspective is crucial to comprehending the development of BPD. Promoting healthy relationships with one or more supportive adult enables the child to…

  5. Integrating Recovery and the Narrative Attachment Systems Perspective to Working through Borderline Personality Disorder

    ERIC Educational Resources Information Center

    Bernardon, Stephanie; Pernice-Duca, Francesca

    2012-01-01

    Borderline personality disorder (BPD) presents a number of symptoms and adjustment issues for individuals, but it is also associated with a myriad of risks for the larger family system. A systemic perspective is crucial to comprehending the development of BPD. Promoting healthy relationships with one or more supportive adult enables the child to…

  6. Comparison of the efficiencies of attached- versus suspended-growth SBR systems in the treatment of recycled paper mill wastewater.

    PubMed

    Muhamad, Mohd Hafizuddin; Sheikh Abdullah, Siti Rozaimah; Abu Hasan, Hassimi; Abd Rahim, Reehan Adnee

    2015-11-01

    The complexity of residual toxic organics from biologically treated effluents of pulp and paper mills is a serious concern. To date, it has been difficult to choose the best treatment technique because each of the available options has advantages and drawbacks. In this study, two different treatment techniques using laboratory-scale aerobic sequencing batch reactors (SBRs) were tested with the same real recycled paper mill effluent to evaluate their treatment efficiencies. Two attached-growth SBRs using granular activated carbon (GAC) with and without additional biomass and a suspended-growth SBR were used in the treatment of real recycled paper mill effluent at a chemical oxygen demand (COD) level in the range of 800-1300 mg/L, a fixed hydraulic retention time of 24 h and a COD:N:P ratio of approximately 100:5:1. The efficiency of this biological treatment process was studied over a 300-day period. The six most important wastewater quality parameters, namely, chemical oxygen demand (COD), turbidity, ammonia (expressed as NH3-N), phosphorus (expressed as PO4(3)-P), colour, and suspended solids (SS), were measured to compare the different treatment techniques. It was determined that these processes were able to almost completely and simultaneously eliminate COD (99%) and turbidity (99%); the removals of NH3-N (90-100%), PO4(3)-P (66-78%), colour (63-91%), and SS (97-99%) were also sufficient. The overall performance results confirmed that an attached-growth SBR system using additional biomass on GAC is a promising configuration for wastewater treatment in terms of performance efficiency and process stability under fluctuations of organic load. Hence, this hybrid system is recommended for the treatment of pulp and paper mill effluents.

  7. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.

    1994-02-15

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material is described. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly. 11 figures.

  8. Magnetically attached sputter targets

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.

    1994-01-01

    An improved method and assembly for attaching sputtering targets to cathode assemblies of sputtering systems which includes a magnetically permeable material. The magnetically permeable material is imbedded in a target base that is brazed, welded, or soldered to the sputter target, or is mechanically retained in the target material. Target attachment to the cathode is achieved by virtue of the permanent magnets and/or the pole pieces in the cathode assembly that create magnetic flux lines adjacent to the backing plate, which strongly attract the magnetically permeable material in the target assembly.

  9. 22 CFR 121.8 - End-items, components, accessories, attachments, parts, firmware, software and systems.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    .... Firmware includes but is not limited to circuits into which software has been programmed. (f) Software includes but is not limited to the system functional design, logic flow, algorithms, application programs...

  10. 22 CFR 121.8 - End-items, components, accessories, attachments, parts, firmware, software and systems.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... Firmware includes but is not limited to circuits into which software has been programmed. (f) Software includes but is not limited to the system functional design, logic flow, algorithms, application programs...

  11. Increasing the Power of a University Computing System with Attached Array Processors.

    ERIC Educational Resources Information Center

    Grimison, Alec

    1982-01-01

    Array processors are emerging as one cost-effective way of increasing the computing power of existing university computer systems. Two array processor installations at Cornell University and implications for other colleges and universities are discussed. (Author/JN)

  12. Expression of androgen receptor mRNA in the brain of Gekko gecko: implications for understanding the role of androgens in controlling auditory and vocal processes.

    PubMed

    Tang, Y Z; Piao, Y S; Zhuang, L Z; Wang, Z W

    2001-09-17

    The neuroanatomical distribution of androgen receptor (AR) mRNA-containing cells in the brain of a vocal lizard, Gekko gecko, was mapped using in situ hybridization. Particular attention was given to auditory and vocal nuclei. Within the auditory system, the cochlear nuclei, the central nucleus of the torus semicircularis, the nucleus medialis, and the medial region of the dorsal ventricular ridge contained moderate numbers of labeled neurons. Neurons labeled with the AR probe were located in many nuclei related to vocalization. Within the hindbrain, the mesencephalic nucleus of the trigeminal nerve, the vagal part of the nucleus ambiguus, and the dosal motor nucleus of the vagus nerve contained many neurons that exhibited strong expression of AR mRNA. Neurons located in the peripheral nucleus of the torus in the mesencephalon exhibited moderate levels of hybridization. Intense AR mRNA expression was also observed in neurons within two other areas that may be involved in vocalization, the medial preoptic area and the hypoglossal nucleus. The strongest mRNA signals identified in this study were found in cells of the pallium, hypothalamus, and inferior nucleus of the raphe. The expression patterns of AR mRNA in the auditory and vocal control nuclei of G. gecko suggest that neurons involved in acoustic communication in this species, and perhaps related species, are susceptible to regulation by androgens during the breeding season. The significance of these results for understanding the evolution of reptilian vocal communication is discussed.

  13. Emergency Face-Mask Removal Effectiveness: A Comparison of Traditional and Nontraditional Football Helmet Face-Mask Attachment Systems

    PubMed Central

    Swartz, Erik E.; Belmore, Keith; Decoster, Laura C.; Armstrong, Charles W.

    2010-01-01

    Abstract Context: Football helmet face-mask attachment design changes might affect the effectiveness of face-mask removal. Objective: To compare the efficiency of face-mask removal between newly designed and traditional football helmets. Design: Controlled laboratory study. Setting: Applied biomechanics laboratory. Participants: Twenty-five certified athletic trainers. Intervention(s): The independent variable was face-mask attachment system on 5 levels: (1) Revolution IQ with Quick Release (QR), (2) Revolution IQ with Quick Release hardware altered (QRAlt), (3) traditional (Trad), (4) traditional with hardware altered (TradAlt), and (5) ION 4D (ION). Participants removed face masks using a cordless screwdriver with a back-up cutting tool or only the cutting tool for the ION. Investigators altered face-mask hardware to unexpectedly challenge participants during removal for traditional and Revolution IQ helmets. Participants completed each condition twice in random order and were blinded to hardware alteration. Main Outcome Measure(s): Removal success, removal time, helmet motion, and rating of perceived exertion (RPE). Time and 3-dimensional helmet motion were recorded. If the face mask remained attached at 3 minutes, the trial was categorized as unsuccessful. Participants rated each trial for level of difficulty (RPE). We used repeated-measures analyses of variance (α  =  .05) with follow-up comparisons to test for differences. Results: Removal success was 100% (48 of 48) for QR, Trad, and ION; 97.9% (47 of 48) for TradAlt; and 72.9% (35 of 48) for QRAlt. Differences in time for face-mask removal were detected (F4,20  =  48.87, P  =  .001), with times ranging from 33.96 ± 14.14 seconds for QR to 99.22 ± 20.53 seconds for QRAlt. Differences were found in range of motion during face-mask removal (F4,20  =  16.25, P  =  .001), with range of motion from 10.10° ± 3.07° for QR to 16.91° ± 5.36° for TradAlt. Differences also were detected

  14. 22 CFR 121.8 - End-items, components, accessories, attachments, parts, firmware, software, and systems.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    .... Firmware includes but is not limited to circuits into which software has been programmed. (f) Software includes but is not limited to the system functional design, logic flow, algorithms, application programs... component. Firmware includes but is not limited to circuits into which software has been programmed. (f...

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

    PubMed

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

    2017-04-24

    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 (fR), 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 fR, 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

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

    PubMed Central

    Rocha, Sara; Santos, Xavier

    2017-01-01

    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 controlling the

  17. Helmet retention system types as a risk factor to properly attach the chin strap.

    PubMed

    Freitas, C A; Furtado, A M; Petterle, R R; Pimentel, S K; Carvalho, F H

    2017-07-31

    This study aimed to determine the factors associated with the incorrect use of a helmet retention system (loose or open) and how often this happens. This was an observational transversal study conducted in Curitiba, Brazil. Trained observers positioned at traffic lights collected information about the helmet fixation mode, the helmet model (full-face, open-face, modular, half), and the helmet retention system model (micrometric, double-D, fast-release). Additional data including position on the motorcycle, gender, and function of the motorcycle (as a work vehicle) were collected. The observers, collection site, and periods were randomly selected by lots. From a total of 3,050 motorcyclists, 1,807 (59.2%) had their helmets fastened correctly, 907 (29.7%) had the retention system fastened loosely, and in 336 (11.0%), the retention system was completely open. Increased odds of incorrect use were observed for the fast-release and double-D buckles compared to the micrometrics buckles, with a fixed odds ratio (OR) of 4.62 (95% confidence interval [CI], 3.89-5.51) and 3.54 (95% CI, 2.46-5.09), respectively (P <.0001). Full-face helmets had a higher chance of incorrect use (P <.0001), and passengers had a higher incidence of incorrect use of the helmet than drivers (P <.0001). An important risk factor related to the incorrect use of the helmet was the type of retention system. The helmet model and being a passenger had a secondary influence on incorrect use of helmets.

  18. Evolved Mechanisms in Adolescent Anxiety and Depression Symptoms: The Role of the Attachment and Social Rank Systems

    ERIC Educational Resources Information Center

    Irons, C.; Gilbert, P.

    2005-01-01

    One hundred and forty adolescent students were assessed on measures of attachment, social rank (social comparison and submissive behaviour), and depression and anxiety symptoms. Secure attachment was significantly correlated with positive social comparison and inversely with submissive behaviour, depression and anxiety symptoms. In contrast,…

  19. Effects of therapeutic interventions for foster children on behavioral problems, caregiver attachment, and stress regulatory neural systems.

    PubMed

    Fisher, Philip A; Gunnar, Megan R; Dozier, Mary; Bruce, Jacqueline; Pears, Katherine C

    2006-12-01

    Young children in foster care are exposed to high levels of stress. These experiences place foster children at risk for poor social, academic, and mental heath outcomes. The role of adverse events in stimulating neurobiological stress responses presumably plays a role in shaping neural systems that contribute to these problems. Systematic and developmentally well-timed interventions might have the potential to change developmental trajectories and promote resilience. Moreover, understanding how specific dimensions of early adversity affect underlying stress response systems and how alterations in these systems are related to later psychosocial outcomes might facilitate more precise and targeted interventions. Data are drawn from two ongoing randomized trials involving foster infants/toddlers and preschoolers. Consistent with prior animal models of early adversity, these studies have shown that early adversity-particularly neglect, younger age at first foster placement, and higher number of placements-is associated with altered hypothalamic-pituitary-adrenal (HPA) axis function. The interventions under investigation have produced evidence that it is possible to impact many areas that have been negatively affected by early stress, including HPA axis activity, behavior, and attachment to caregivers.

  20. L-8: Docking Systems and Other Attachment/Release Mechanisms and Related Technologies

    NASA Technical Reports Server (NTRS)

    Lewis, James

    2016-01-01

    We are sharpening our focus on Human Space Flight (HSF) Exploration Beyond Low Earth Orbit. We want to ensure that HSF technologies are ready to take Humans to Mars in the 2030s. Various Roadmaps define the needed technologies. We are attempting to define our activities and dependencies. Our Goal: Get within 8 years of launching humans to Mars (L-8) by 2025. Develop and Mature the technologies and systems needed. Develop and Mature the personnel needed. We need collaborators to make it happen, and we think they can benefit by working with us.

  1. Outcompeted by an invader? Interference and exploitative competition between tropical house gecko (Hemidactylus mabouia) and Barbados leaf-toed gecko (Phyllodactylus pulcher) for diurnal refuges in anthropogenic coastal habitats.

    PubMed

    Williams, Robert; Pernetta, Angelo P; Horrocks, Julia A

    2016-05-01

    House geckos in the genus Hemidactylus are highly successful colonizers of regions beyond their native range, with colonization often resulting in displacement of native gecko species through competitive interactions for daytime refuge (crevices) and prey resources. We report on data collected from nighttime surveys undertaken in April-May 2014 on Barbados, West Indies, that focused on the distribution and abundance of the endemic Barbados leaf-toed gecko (Phyllodactylus pulcher) and the introduced tropical house gecko (Hemidactylus mabouia) along unlit coastal walls and among boulders in the grounds of a hotel resort. In contrast to patterns of displacement of native species by H. mabouia seen elsewhere, P. pulcher was more abundant than H. mabouia on coastal walls, whereas the latter was found in greater numbers using boulders at this site. Walls and boulders differed with regard to availability of diurnal refugia suitable for geckos, with the walls having high frequency of small crevices with openings <20 mm, and boulders offering very little cover other than the underside of the boulder itself. To investigate whether this niche separation was a result of differences in diurnal refuge use between the species, we conducted experimental trials in which geckos were allowed to select between refugia with different characteristics. Both species selected for narrower and warmer refugia, and refugia that had been previously occupied by the other species. These shared preferences for refugia type suggest that other factors underlie the niche separation observed in the field. In supporting high densities of P. pulcher, coastal walls could offer important secondary habitat by augmenting the natural cliff side habitat of this endemic gecko, a finding that could be exploited for the conservation of this candidate species for Critically Endangered classification.

  2. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration

    PubMed Central

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-01-01

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40phox and p47phox) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration. PMID:26853930

  3. Investigation of bioinspired gecko fibers to improve adhesion of HeartLander surgical robot.

    PubMed

    Tortora, Giuseppe; Glass, Paul; Wood, Nathan; Aksak, Burak; Menciassi, Arianna; Sitti, Metin; Riviere, Cameron

    2012-01-01

    HeartLander is a medical robot proposed for minimally invasive epicardial intervention on the beating heart. To date, all prototypes have used suction to gain traction on the epicardium. Gecko-foot-inspired micro-fibers have been proposed for repeatable adhesion to surfaces. In this paper, a method for improving the traction of HeartLander on biological tissue is presented. The method involves integration of gecko-inspired fibrillar adhesives on the inner surfaces of the suction chambers of HeartLander. Experiments have been carried out on muscle tissue ex vivo assessing the traction performance of the modified HeartLander with bio-inspired adhesive. The adhesive fibers are found to improve traction on muscle tissue by 57.3 %.

  4. Reactive oxygen species generated from skeletal muscles are required for gecko tail regeneration.

    PubMed

    Zhang, Qing; Wang, Yingjie; Man, Lili; Zhu, Ziwen; Bai, Xue; Wei, Sumei; Liu, Yan; Liu, Mei; Wang, Xiaochuan; Gu, Xiaosong; Wang, Yongjun

    2016-02-08

    Reactive oxygen species (ROS) participate in various physiological and pathological functions following generation from different types of cells. Here we explore ROS functions on spontaneous tail regeneration using gecko model. ROS were mainly produced in the skeletal muscle after tail amputation, showing a temporal increase as the regeneration proceeded. Inhibition of the ROS production influenced the formation of autophagy in the skeletal muscles, and as a consequence, the length of the regenerating tail. Transcriptome analysis has shown that NADPH oxidase (NOX2) and the subunits (p40(phox) and p47(phox)) are involved in the ROS production. ROS promoted the formation of autophagy through regulation of both ULK and MAPK activities. Our results suggest that ROS produced by skeletal muscles are required for the successful gecko tail regeneration.

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

    PubMed Central

    Higham, Timothy E.; Russell, Anthony P.

    2010-01-01

    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. PMID:19740891

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

    PubMed

    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 < .01). Hatchling mass was not affected. Embryos exposed to substantially augmented visual stimulation demonstrated a postnatal preference for patterned light in a simultaneous choice test at 24 hr of age (p < .01). Control embryos demonstrated a preference for normal light conditions (p < .01), whereas experimental embryos exposed to lesser amounts of prenatal visual stimulation did not show a preference for either stimulus. At 1 week of age, geckos in all conditions failed to exhibit a preference for either stimulus.

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

    PubMed

    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.

  8. Molecular phylogenetic relationships among species of the Malagasy-Comoran gecko genus Paroedura (Squamata: Gekkonidae).

    PubMed

    Jackman, Todd R; Bauer, Aaron M; Greenbaum, Eli; Glaw, Frank; Vences, Miguel

    2008-01-01

    We use approximately 3100bp of mitochondrial (ND2, ND4) and nuclear (RAG1, phosducin) DNA sequence data to recover phylogenetic relationships among 14 of the 16 recognized taxa of the lizard genus Paroedura as well as two undescribed forms. These geckos are endemic to Madagascar and the Comores and are popularly kept and bred by herpetoculturalists. The closest relative of Paroedura is another Indian Ocean leaf-toed gecko, Ebenavia. Both Bayesian inference and maximum parsimony strongly support the monophyly of two major clades within Paroedura that conflict with existing species group assignments based on scale characteristics. Our well-resolved tree elucidates a biogeographic pattern in which eastern Paroedura are most basal and western and south-western species form a monophyletic group. Our data demonstrate the phylogenetic utility of phosducin, a novel marker in squamate phylogenetics, at the intrageneric level.

  9. Non-homologous sex chromosomes in two geckos (Gekkonidae: Gekkota) with female heterogamety.

    PubMed

    Matsubara, Kazumi; Gamble, Tony; Matsuda, Yoichi; Zarkower, David; Sarre, Stephen D; Georges, Arthur; Graves, Jennifer A Marshall; Ezaz, Tariq

    2014-01-01

    Evaluating homology between the sex chromosomes of different species is an important first step in deducing the origins and evolution of sex-determining mechanisms in a clade. Here, we describe the preparation of Z and W chromosome paints via chromosome microdissection from the Australian marbled gecko (Christinus marmoratus) and their subsequent use in evaluating sex chromosome homology with the ZW chromosomes of the Kwangsi gecko (Gekko hokouensis) from eastern Asia. We show that the ZW sex chromosomes of C. marmoratus and G. hokouensis are not homologous and represent independent origins of female heterogamety within the Gekkonidae. We also show that the C. marmoratus Z and W chromosomes are genetically similar to each other as revealed by C-banding, comparative genomic hybridization, and the reciprocal painting of Z and W chromosome probes. This implies that sex chromosomes in C. marmoratus are at an early stage of differentiation, suggesting a recent origin.

  10. The multiple cantilever system: a solution for a failed precision attachment denture case.

    PubMed

    Schweikert, E D

    1999-01-01

    Multiple-cantilevered pontic bridges can be a great alternative to dental implants and distal extension prostheses. Dental hygiene must be considered the most important factor in preserving the status quo of the permanent restoration. Traumatic occlusion, which can occur because of the widened periodontal space and greater mobility of a multiple-cantilever bridge, is not automatically a sign of failure. As long as the mobility of the fixed bridge does not increase and the patient can function and feel comfortable with it, a successful therapy can be concluded. If marginal periodontitis exists, destruction of the cervical ligaments, bone resorption, and apical migration of the epithelium will occur. Through loss of the supportive structures, hypermobility will increase. If the destructive factors of marginal periodontitis are not eliminated, the hypermobility can interfere with masticatory function. It is important that patients be made aware of this possibility. Regular recalls in the beginning of the maintenance program will emphasize the importance of the home-care system.

  11. Frazzled promotes growth cone attachment at the source of a Netrin gradient in the Drosophila visual system

    PubMed Central

    Akin, Orkun; Zipursky, S Lawrence

    2016-01-01

    Axon guidance is proposed to act through a combination of long- and short-range attractive and repulsive cues. The ligand-receptor pair, Netrin (Net) and Frazzled (Fra) (DCC, Deleted in Colorectal Cancer, in vertebrates), is recognized as the prototypical effector of chemoattraction, with roles in both long- and short-range guidance. In the Drosophila visual system, R8 photoreceptor growth cones were shown to require Net-Fra to reach their target, the peak of a Net gradient. Using live imaging, we show, however, that R8 growth cones reach and recognize their target without Net, Fra, or Trim9, a conserved binding partner of Fra, but do not remain attached to it. Thus, despite the graded ligand distribution along the guidance path, Net-Fra is not used for chemoattraction. Based on findings in other systems, we propose that adhesion to substrate-bound Net underlies both long- and short-range Net-Fra-dependent guidance in vivo, thereby eroding the distinction between them. DOI: http://dx.doi.org/10.7554/eLife.20762.001 PMID:27743477

  12. Thermoelectric generating system attached to a carburizing furnace at Komatsu Ltd., Awazu Plant

    NASA Astrophysics Data System (ADS)

    Kaibe, H.; Makino, K.; Kajihara, T.; Fujimoto, S.; Hachiuma, H.

    2012-06-01

    At the end of October 2009, KELK Ltd. started a field test of the thermoelectric generation system at a carburizing furnace of Komatsu Ltd., Awazu Plant. Residual carburizing gas based on CO, H2 and N2 is burned resulting that 20-30 kW range of flame constantly heats up the hot side of TEG. A single unit of TEG consists of 16 of the Bi-Te thermo-modules, each of which has a size of 50 × 50 × 4.2 mm3 and can generate 24W under the circumstance of 280 °C and 30 °C of hot side and cold side temperature, respectively [1]. 16 modules are separated into 4 groups and they are connected electrically depending on design concept, namely in case of focusing on reliability, parallel connection are used and in case of on simplicity and high-voltage transmission, series connection is preferably employed. The module is being life-time tested at various conditions. For instance, 10,000 of heat cycling under the hot side temperature between 250 and 50 °C with a constant cold side temperature at 30 °C gives within a few percent degrade. Both buck-and booster-type DC/DC converters controlled by one chip computer were set up and Maximum Power Point Tracking (MPPT) was well facilitated to search for the maximum output power depending on the hot and cold temperature. The electric output power from the 16 modules is summed up to charge 4 lead storage batteries (12V-65Ah) and then through DC/AC inverters electricity goes to LED light tubes inside the factory. 214 W can be generated and 180 W is delivered to the batteries.

  13. The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.

    PubMed Central

    Liang, J; Steinberg, G; Livnah, N; Sheves, M; Ebrey, T G; Tsuda, M

    1994-01-01

    A visual pigment is composed of retinal bound to its apoprotein by a protonated Schiff base linkage. Light isomerizes the chromophore and eventually causes the deprotonation of this Schiff base linkage at the meta II stage of the bleaching cycle. The meta II intermediate of the visual pigment is the active form of the pigment that binds to and activates the G protein transducin, starting the visual cascade. The deprotonation of the Schiff base is mandatory for the formation of meta II intermediate. We studied the proton binding affinity, pKa, of the Schiff base of both octopus rhodopsin and the gecko cone pigment P521 by spectral titration. Several fluorinated retinal analogs have strong electron withdrawing character around the Schiff base region and lower the Schiff base pKa in model compounds. We regenerated octopus and gecko visual pigments with these fluorinated and other retinal analogs. Experiments on these artificial pigments showed that the spectral changes seen upon raising the pH indeed reflected the pKa of the Schiff base and not the denaturation of the pigment or the deprotonation of some other group in the pigment. The Schiff base pKa is 10.4 for octopus rhodopsin and 9.9 for the gecko cone pigment. We also showed that although the removal of Cl- ions causes considerable blue-shift in the gecko cone pigment P521, it affects the Schiff base pKa very little, indicating that the lambda max of visual pigment and its Schiff base pKa are not tightly coupled. PMID:7948697

  14. The mitochondrial genome of the gold-dust day gecko, Phelsuma laticauda (Sauria, Gekkota, Gekkonidae).

    PubMed

    Yan, Jie; Tian, Chao; Bauer, Aaron M; Zhou, Kaiya

    2016-01-01

    We sequenced the nearly complete mitochondrial genome of the gold-dust day gecko, Phelsuma laticauda, which is native to northern Madagascar. The mitogenome is 15,416 bp in size, consisting of 37 genes coding for 13 proteins, 22 tRNAs, and 2 rRNAs. Due to the unsuccessful sequencing of the control region, the length is relatively shorter than that of other gekkonids. The gene organization conforms to the vertebrate consesus gene arrangement.

  15. Electrocardiogram, heart movement and heart rate in the awake gecko (Hemidactylus mabouia).

    PubMed

    Germer, Carina M; Tomaz, Juliana M; Carvalho, Ana F; Bassani, Rosana A; Bassani, José W M

    2015-01-01

    The electrocardiogram (ECG) is the simplest and most effective non-invasive method to assess the electrical activity of the heart and to obtain information on the heart rate (HR) and rhythm. Because information on the HR of very small reptiles (body mass <10 g) is still scarce in the literature, in the present work we describe a procedure for recording the ECG in non-anesthetized geckos (Hemidactylus mabouia, Moreau de Jonnès, 1818) under different conditions, namely manual restraint (MR), spontaneous tonic immobility (TI), and in the non-restrained condition (NR). In the gecko ECG, the P, QRS and T waves were clearly distinguishable. The HR was 2.83 ± 0.02 Hz under MR, which was significantly greater (p < 0.001) than the HR under the TI (1.65 ± 0.09 Hz) and NR (1.60 ± 0.10 Hz) conditions. Spontaneously beating isolated gecko hearts contracted at 0.84 ± 0.03 Hz. The in vitro beating rate was affected in a concentration-dependent fashion by adrenoceptor stimulation with noradrenaline, as well as by the muscarinic cholinergic agonist carbachol, which produced significant positive and negative chronotropic effects, respectively (p < 0.001). To our knowledge, this is the first report on the ECG morphology and HR values in geckos, particularly under TI. The methodology and instrumentation developed here are useful for non-invasive in vivo physiological and pharmacological studies in small reptiles without the need of physical restraint or anesthesia.

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

    PubMed

    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 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.

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

    USGS Publications Warehouse

    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.

  18. The pKa of the protonated Schiff bases of gecko cone and octopus visual pigments.

    PubMed

    Liang, J; Steinberg, G; Livnah, N; Sheves, M; Ebrey, T G; Tsuda, M

    1994-08-01

    A visual pigment is composed of retinal bound to its apoprotein by a protonated Schiff base linkage. Light isomerizes the chromophore and eventually causes the deprotonation of this Schiff base linkage at the meta II stage of the bleaching cycle. The meta II intermediate of the visual pigment is the active form of the pigment that binds to and activates the G protein transducin, starting the visual cascade. The deprotonation of the Schiff base is mandatory for the formation of meta II intermediate. We studied the proton binding affinity, pKa, of the Schiff base of both octopus rhodopsin and the gecko cone pigment P521 by spectral titration. Several fluorinated retinal analogs have strong electron withdrawing character around the Schiff base region and lower the Schiff base pKa in model compounds. We regenerated octopus and gecko visual pigments with these fluorinated and other retinal analogs. Experiments on these artificial pigments showed that the spectral changes seen upon raising the pH indeed reflected the pKa of the Schiff base and not the denaturation of the pigment or the deprotonation of some other group in the pigment. The Schiff base pKa is 10.4 for octopus rhodopsin and 9.9 for the gecko cone pigment. We also showed that although the removal of Cl- ions causes considerable blue-shift in the gecko cone pigment P521, it affects the Schiff base pKa very little, indicating that the lambda max of visual pigment and its Schiff base pKa are not tightly coupled.

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

    PubMed Central

    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. PMID:28120867

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

    PubMed Central

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

    2014-01-01

    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. PMID:25323067

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  3. Temperature, field activity and post-feeding metabolic response in the Asian house gecko, Hemidactylus frenatus.

    PubMed

    Lei, Juan; Booth, David T

    2014-10-01

    Temperature has significant effects on physiological activities and geographical distribution of ectotherms. The Asian house gecko Hemidactylus frenatus has become one of the most widely distributed reptiles in the world and is an invasive species in Australia. Since being introduced into northern Australia, Asian house geckos have spread rapidly and expanded into south-east Queensland and northern New South Wales. Despite their rapid spread, there have been few studies that address thermal adaptability of this species. In order to understand how temperature might limit the distribution and feeding behavior of H. frenatus we observed gecko foraging activities in the wild over the winter period, measured the temperature at which voluntary feeding ceases, and assessed the effect of temperature (30, 25, 20, and 18 °C) on post-feeding metabolic rate. Resting metabolic rate and post-feeding peak in metabolic rate decreased with low temperature, while the duration of elevated metabolic rate after feeding increased at lower temperature. The SDA coefficient (a ratio of the energy expended due to the post-feeding rise in metabolic rate to the energy contained within the meal) did not change systematically with ambient temperature. Field observations and voluntary feeding experiments showed that H. frenatus stop feeding when ambient temperature drops below 17 °C, so that persistent night time temperatures below 17 °C may be limiting the distribution of this species.

  4. The role of surface chemistry in adhesion and wetting of gecko toe pads.

    PubMed

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

    2014-10-17

    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.

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

    PubMed

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

    PubMed Central

    2014-01-01

    Background 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. Results 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. Conclusions 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. PMID:24974837

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Preparation and properties of polyurethane/silicone materials for biomimetic gecko setae

    NASA Astrophysics Data System (ADS)

    Yu, Min; Dai, Zhendong; Yang, Shengrong

    2014-03-01

    In the biomimetic design of gecko setae, it is necessary to select materials with appropriate adhesive properties and to understand the effects of materials on normal and tangential adhesive forces. To meet the adhesion performance requirements of the biomimetic gecko robot foot, in this study, performance-improved polyurethane/silicone polymer materials were designed and synthesized, and the normal adhesion and tangential adhesion were measured using an adhesive friction comprehensive tester. The results show that normal adhesion increased with an increase in load when the normal load is small; when the normal load exceeds a critical value, the increase in normal adhesion slows and adhesion saturates. Under the condition of an adhesive state, the tangential adhesive force was larger for a smaller negative normal force, and a relatively large tangential adhesive force could be generated with a very small negative normal force. The elastic modulus of the synthetic polyurethane/silicone material varied with varying ratios of components, and it increased with increasing urethane content. Polyurethane/silicone material with about 30% polyurethane provided greater adhesion than other materials with different contents of polyurethane. The results provide a basis for the choice of biomimetic materials of the biomimetic gecko robot foot.

  9. Paternal Attachment, Parenting Beliefs and Children's Attachment

    ERIC Educational Resources Information Center

    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…

  10. Paternal Attachment, Parenting Beliefs and Children's Attachment

    ERIC Educational Resources Information Center

    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…

  11. Biophysical Characterization of the Type III Secretion System Translocator Proteins and the Translocator Proteins Attached to Bacterium-Like Particles.

    PubMed

    Chen, Xiaotong; Choudhari, Shyamal P; Kumar, Prashant; Toth, Ronald T; Kim, Jae Hyun; Van Roosmalen, Maarten L; Leenhouts, Kees; Middaugh, C Russell; Picking, Wendy L; Picking, William D

    2015-12-01

    Diarrhea caused by Shigella, Salmonella, and Yersinia is an important public health problem, but development of safe and effective vaccines against such diseases is challenging. A new antigen delivery platform called bacterium-like particles (BLPs) was explored as a means for delivering protective antigens from the type III secretion systems (T3SS) of these pathogens. BLPs are peptidoglycan skeletons derived from Lactococcus lactis that are safe for newborns and can carry multiple antigens. Hydrophobic T3SS translocator proteins were fused to a peptidoglycan anchor (PA) for BLP attachment. The proteins and protein-BLP complexes associated with BLPs were characterized and the resulting data used to create three-index empirical phase diagrams (EPDs). On the basis of these EPDs, IpaB (Shigella) and SipB (Salmonella) behave distinctly from YopB (Yersinia) under different environmental stresses. Adding the PA domain appears to enhance the stability of both the PA and translocator proteins, which was confirmed using differential scanning calorimetry, and although the particles dominated the spectroscopic signals in the protein-loaded BLPs, structural changes in the proteins were still detected. The protein-BLPs were most stable near neutral pH, but these proteins' hydrophobicity made them sensitive to environmental stresses. © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

  12. Fluorescence lifetime attachment LIFA

    NASA Astrophysics Data System (ADS)

    van der Oord, Cornelius J. R.; Stoop, Karel W. J.; van Geest, Lambertus K.

    2001-05-01

    We present the Lambert Instruments Fluorescence Lifetime Attachment LIFA. LIFA enables easy to use and affordable microscopy and macroscopic FLIM. The system implements the homodyne detection scheme for measuring the fluorescence lifetime in each pixel of the image. The microscopy system features an ultra bright LED illuminator, the LI-(mu) Cam intensified CCD camera a high frequency signal generator. The illuminator replaces the excitation light source of a standard fluorescence microscopy, while the LI-(mu) CAM intensified CCD camera is attached to the photo-port. Both the illuminator and the intensifier are modulated at a frequency up to 100 MHz at a series of phase differences. The lifetime image is calculated from the series of images on a personal computer.

  13. Ceramic blade attachment system

    DOEpatents

    Boyd, G.L.

    1995-04-11

    A retainer ring is arranged to mount turbine blades to a turbine disk so that aerodynamic forces produced by a gas turbine engine are transferred from the turbine blades to the turbine disk to cause the turbine blades and turbine disk to rotate, but so that centrifugal forces of the turbine blades resulting from the rotation of the turbine blades and turbine disk are not transferred from the turbine blades to the turbine disk. 6 figures.

  14. Ceramic blade attachment system

    SciTech Connect

    Boyd, Gary L.

    1995-01-01

    A retainer ring is arranged to mount turbine blades to a turbine disk so that aerodynamic forces produced by a gas turbine engine are transferred from the turbine blades to the turbine disk to cause the turbine blades and turbine disk to rotate, but so that centrifugal forces of the turbine blades resulting from the rotation of the turbine blades and turbine disk are not transferred from the turbine blades to the turbine disk.

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

    PubMed

    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.

  16. Direct embryo tagging and identification system by attachment of biofunctionalized polysilicon barcodes to the zona pellucida of mouse embryos.

    PubMed

    Novo, Sergi; Penon, Oriol; Barrios, Leonardo; Nogués, Carme; Santaló, Josep; Durán, Sara; Gómez-Matínez, Rodrigo; Samitier, Josep; Plaza, José Antonio; Pérez-García, Luisa; Ibáñez, Elena

    2013-06-01

    Is the attachment of biofunctionalized polysilicon barcodes to the outer surface of the zona pellucida an effective approach for the direct tagging and identification of cultured embryos? The results achieved provide a proof of concept for a direct embryo tagging system using biofunctionalized polysilicon barcodes, which could help to minimize the risk of mismatching errors (mix-ups) in human assisted reproduction technologies. Even though the occurrence of mix-ups is rare, several cases have been reported in fertility clinics around the world. Measures to prevent the risk of mix-ups in human assisted reproduction technologies are therefore required. Mouse embryos were tagged with 10 barcodes and the effectiveness of the tagging system was tested during fresh in vitro culture (n=140) and after embryo cryopreservation (n = 84). Finally, the full-term development of tagged embryos was evaluated (n =105). Mouse pronuclear embryos were individually rolled over wheat germ agglutinin-biofunctionalized polysilicon barcodes to distribute them uniformly around the ZONA PELLUCIDA surface. Embryo viability and retention of barcodes were determined during 96 h of culture. The identification of tagged embryos was performed every 24 h in an inverted microscope and without embryo manipulation to simulate an automatic reading procedure. Full-term development of the tagged embryos was assessed after their transfer to pseudo-pregnant females. To test the validity of the embryo tagging system after a cryopreservation process, tagged embryos were frozen at the 2-cell stage using a slow freezing protocol, and followed in culture for 72 h after thawing. Neither the in vitro or in vivo development of tagged embryos was adversely affected. The tagging system also proved effective during an embryo cryopreservation process. Global identification rates higher than 96 and 92% in fresh and frozen-thawed tagged embryos, respectively, were obtained when simulating an automatic barcode reading

  17. Applicability of linearized-theory attached-flow methods to design and analysis of flap systems at low speeds for thin swept wings with sharp leading edges

    NASA Technical Reports Server (NTRS)

    Carlson, Harry W.; Darden, Christine M.

    1987-01-01

    Low-speed experimental force and data on a series of thin swept wings with sharp leading edges and leading and trailing-edge flaps are compared with predictions made using a linearized-theory method which includes estimates of vortex forces. These comparisons were made to assess the effectiveness of linearized-theory methods for use in the design and analysis of flap systems in subsonic flow. Results demonstrate that linearized-theory, attached-flow methods (with approximate representation of vortex forces) can form the basis of a rational system for flap design and analysis. Even attached-flow methods that do not take vortex forces into account can be used for the selection of optimized flap-system geometry, but design-point performance levels tend to be underestimated unless vortex forces are included. Illustrative examples of the use of these methods in the design of efficient low-speed flap systems are included.

  18. 48 CFR 204.7105 - Contract exhibits and attachments.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... attachments. 204.7105 Section 204.7105 Federal Acquisition Regulations System DEFENSE ACQUISITION REGULATIONS... 204.7105 Contract exhibits and attachments. Follow the procedures at PGI 204.7105 for use and numbering of contract exhibits and attachments....

  19. Effect of abutment angulation in the retention and durability of three overdenture attachment systems: An in vitro study

    PubMed Central

    Ustrell, Raul; Mendes, Jose Manuel; Braga, Ana Cristina; Berastegui, Esther

    2016-01-01

    PURPOSE This in vitro study investigated and compared the durability and retention of three types of attachments. MATERIALS AND METHODS Three commercially available attachments were investigated: Clix®, Dalbo-Plus® and Locator®. In total, 72 samples of these attachments were placed in the acrylic resin forms and subjected to mechanical testing (5400 cycles of insertion and removal) over the respective ball or Locator abutments immersed in artificial saliva at pH 7 and 37℃. The abutments were placed at angulations of 0°, 10° and 20°. The retention force was recorded at the beginning and after 540, 1080, 2160, 3240, 4320 and 5400 insertion-removal cycles. RESULTS The results revealed that there were significant differences in the average values of the insertion/removal force due to angulation (F (2.48) = 343619, P<.05) and the type of attachment (F (7.48) = 23.220, P<.05). CONCLUSION Greater angulation of the abutments was found to influence the retention capacity of the attachments, and the fatigue test simulating 5 years of denture insertion and removal did not produce wear in the metal abutments. PMID:26949484

  20. An experimental study of double-peeling mechanism inspired by biological adhesive systems

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Raguseo, Saverio; Gorb, Stanislav N.

    2017-02-01

    Double- (or multiple-) peeling systems consist of two (or numerous) tapes adhering to a substrate and having a common hinge, where the pulling force is applied. Biological systems, consisting of tape-like (or spatula-like) contact elements, are widely observed in adhesive pads of flies, beetles, spiders, and geckos. It was previously hypothesized and analytically modeled that the simultaneous use of two or more such tape-like contacts in the opposite movement of contralateral legs during ceiling locomotion leads to enhanced, robust, and stable overall attachment, if compared to independently working contact points. In this paper, this biological solution for smart adhesion is demonstrated in an experiment using elastic adhesive tapes. The obtained results not only aided in explaining the functional mechanism of biological adhesive systems, but also in providing an experimental proof for biological observations and previous theoretical models.

  1. Phylogeography and diversification history of the day-gecko genus Phelsuma in the Seychelles islands

    PubMed Central

    2013-01-01

    Background Lying in a shallow continental shelf cyclically affected by oscillating sea levels since the Miocene, the Seychelles islands are particularly interesting for evolutionary studies. Recent molecular studies are generating an emerging picture of the origin of its biota, yet very little is known regarding their phylogeographic structure or on the factors promoting diversification within the archipelago. Here we aimed to obtain a detailed depiction of the genetic structure and evolution of one of the most widespread vertebrate groups in the archipelago: the day-geckos of the genus Phelsuma. In parallel, we aimed to infer divergence times between species and subspecies, testing a long-standing hypothesis that argues for different time since sympatry between species as the cause of their different morphological differentiation across the archipelago. Results Molecular data corroborated the existence of two main lineages, corresponding to the two currently recognized species. Divergences between species likely date back to the Mio-Pliocene, while more recent, Pleistocenic, divergences are suggested within each species. Populations from outer islands share mtDNA haplotypes with inner island populations, suggesting very recent dispersals (or introductions). We found no evidence of current gene flow between species, but results pointed to the possibility of gene flow between (now allopatric) subspecies. Time estimates suggest a synchronous divergence within each species (between island groups). Conclusions The geographic patterns of genetic variation agree with previous taxonomic subdivisions within each species and the origin of outer islands populations is clearly tracked. The similar intraspecific divergence time estimates obtained suggest that the differential body-size differentiation between species within each group of islands may be driven by factors other than character displacement proportional to time since sympatry, as previously suggested. These

  2. Attachment Representation of Institutionalized Children in Japan

    ERIC Educational Resources Information Center

    Katsurada, Emiko

    2007-01-01

    This exploratory study represents one of the first attachment investigations of Japanese children who have been institutionalized. Mental representation of attachment was assessed using George and Solomon's (1990, 1996, 2000) Attachment Doll Play Classification System of the Bretherton et al. (1990) doll play story stems. Participants were 32…

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

    PubMed Central

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

    2012-01-01

    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. PMID:22977067

  4. Development of a strain/temperature gauge and attachment system for use on carbon composites at elevated temperature

    NASA Astrophysics Data System (ADS)

    Lanius, S. J.; Brasfield, R. G.; Wnuk, S. P.

    1987-03-01

    The difficulties encountered when instrumenting solid rocket motors for acquiring strain data are reviewed, emphasizing the strong temperature dependence due to apparent strain effects. The development of a strain/temperature gage to overcome some of these problems is discussed. This gage is designed to produce low apparent strain when attached to a carbon-carbon substrate. Characterization and performance data for gages attached with ceramic cement to carbon-carbon tensile coupons are presented, and the effect of a flame-sprayed installation process is discussed.

  5. Development of a strain/temperature gauge and attachment system for use on carbon composites at elevated temperature

    NASA Technical Reports Server (NTRS)

    Lanius, S. J.; Brasfield, R. G.; Wnuk, S. P.

    1987-01-01

    The difficulties encountered when instrumenting solid rocket motors for acquiring strain data are reviewed, emphasizing the strong temperature dependence due to apparent strain effects. The development of a strain/temperature gage to overcome some of these problems is discussed. This gage is designed to produce low apparent strain when attached to a carbon-carbon substrate. Characterization and performance data for gages attached with ceramic cement to carbon-carbon tensile coupons are presented, and the effect of a flame-sprayed installation process is discussed.

  6. Electron-attachment processes

    NASA Astrophysics Data System (ADS)

    Christophorou, L. G.; McCorkle, D. L.; Christodoulides, A. A.

    Topics covered include: modes of production of negative ions, techniques for the study of electron attachment processes, dissociative electron attachment to ground state molecules, dissociative electron attachment to hot molecules (effects of temperature on dissociative electron attachment), molecular parent negative ions, and negative ions formed by ion pair processes and by collisions of molecules with ground state and Rydberg atoms.

  7. Complete mitochondrial genome of the San Lucan gecko, Phyllodactylus unctus (Sauria, Gekkota, Phyllodactylidae), in comparison with Tarentola mauritanica.

    PubMed

    Yan, Jie; Tian, Chao; Lv, Linna; Bauer, Aaron M; Zhou, Kaiya

    2014-06-01

    We sequenced the complete mitochondrial genome of the San Lucan gecko, Phyllodactylus unctus, which is endemic to Mexico. The complete mitochondrial genome was 16,881 bp in size, consisting of 37 genes coding for 13 proteins, 2 rRNAs, 22 tRNAs and 1 control region. Its gene arrangement pattern was identical with most vertebrates. We compared the mitochondrial genome of P. unctus with that of the Moorish gecko, Tarentola mauritanica, which is the only other sequenced species from Phyllodactylidae. Nucleotide sequence divergence (p distance) between two mitochondrial genomes was 31.32%. The detailed comparison between the mitochondrial genomes of two species was done.

  8. A new species of arboreal forest-dwelling gecko (Hemidactylus: Squamata: Gekkonidae) from coastal Kenya, East Africa.

    PubMed

    Malonza, Patrick K; Bauer, Aaron M

    2014-04-09

    A new species of Hemidactylus, H. mrimaensis sp. nov., is described from coastal kaya forests of Kenya. This small-sized, arboreal gecko may be distinguished from its probable close relative, the sympatric H. mabouia, by its more slender habitus, golden color, small adult body length (maximum SVL 50 mm in females) and features of scalation including keeled dorsal tubercles in 11-14 longitudinal rows, pointed tubercles on tail larger than those on the dorsum, and 32-34 precloacal pores in males. This gecko may be endemic to the coastal forests and given the ongoing threats to this habitat, the species is of high conservation concern.

  9. Sex recognition in the leopard gecko,Eublepharis macularius (Sauria: Gekkonidae) Possible mediation by skin-derived semiochemicals.

    PubMed

    Mason, R T; Gutzke, W H

    1990-01-01

    Male leopard geckoes,Eublepharis macularius, rely on skin-derived semiochemicals to determine the sex of conspecifics. Males respond to other males with agonistic behavior while females elicit courtship behavior from males. While females were shedding, males responded to them with agonistic behavior. The same females were courted both before and after shedding. An initial survey of hexane-extracted skin lipids from male and female geckoes revealed fatty acids common to both sexes. Several steroid analogs of cholesterol were unique to males while long-chain methyl ketones were unique to females. Results are discussed in the context of skin lipids serving as pheromones in reptiles.

  10. Biofilm Attached Cultivation of Chlorella pyrenoidosa Is a Developed System for Swine Wastewater Treatment and Lipid Production

    PubMed Central

    Cheng, Pengfei; Wang, Yuanzhu; Liu, Tianzhong; Liu, Defu

    2017-01-01

    This study showed the new potential of using soluble contents and heavy metals in swine wastewater as nutrient supplements for the algae Chlorella pyrenoidosa with biofilm attached method. Algae with biofilm attached cultivation grew well in unpasteurized wastewater reaching a biomass productivity of 5.03 g m−2 d−1, lipid content of 35.9% and lipid productivity of 1.80 g m−2 d−1. Chlorella grew in BG11 medium delivered lower values for each of the aforementioned parameters. The FAMEs compositions in the algae paste were mainly consisted of C16:0, C18:2, and C18:3. Algae removed NH4+–N, total phosphorus (TP), and COD by 75.9, 68.4, and 74.8%, respectively. Notably, Zn2+, Cu+, and Fe2+ were removed from wastewater with a ratio of 65.71, 53.64, and 58.89%, respectively. Biofilm attached cultivation of C. pyrenoidosa in swine wastewater containing heavy metals could accumulate considerable biomass and lipid, and the removal ratio of NH4+–N, TP, COD, and as well as heavy metal were high. Treatment of wastewater with biofilm attached cultivation showed an increasingly popular for the concentration of microalgae and environmental sustainability. PMID:28983302

  11. Attached and unattached fractions of short-lived radon decay products in outdoor environments: effect on the human respiratory system.

    PubMed

    Amrane, M; Oufni, L; Misdaq, M A

    2014-12-01

    The authors developed a model for determining the alpha- and beta-activities per unit volume of air due to radon ((222)Rn), thoron ((220)Rn) and their decay products attached and unattached to the aerosol in the outdoor air at the workplace in natural conditions at different locations in Morocco by using both CR-39 and LR-115 type II solid-state nuclear track detectors. In addition, the percentage of (218)Po, (214)Pb and (214)Po radionuclides attached to the aerosols and the unattached fraction f(j) for different values of the attachment rate were evaluated. Radon and thoron concentrations in outdoor air of the studied different locations were found to vary from 9.20±0.8 to 16.30±1.50 Bq m(-3) and 0.22±0.02 to 1.80±0.20 Bq m(-3), respectively. The committed equivalent doses due to the radon short-lived progeny (218)Po and (214)Po attached and unattached to the aerosol air were evaluated in different tissues of the respiratory tract of the members of the public from the inhalation of outdoor air.

  12. Simulation study on a stationary data acquisition SPECT system with multi-pinhole collimators attached to a triple-head gamma camera system.

    PubMed

    Ogawa, Koichi; Ichimura, Yuta

    2014-10-01

    The aim of the study was to develop a new SPECT system that makes it possible to acquire projection data stationary using a triple-head gamma camera system. We evaluated several data acquisition geometry with multi-pinhole collimators attached to a triple-head gamma camera system. The number of pinholes for each camera was three to twelve, and we located these holes on collimator plates adequately. These collimator holes were tilted by predefined angles to efficiently cover the field of view of the data acquisition system. Acquired data were reconstructed with the OS-EM method. In the simulations, we used a three-dimensional point source phantom, brain phantom, and myocardial phantom. Attenuation correction was conducted with the x-ray CT image of the corresponding slice. Reconstructed images of the point source phantom showed that the spatial resolution could be improved with the small number of pinholes. On the other hand, reconstructed images of the brain phantom showed that the large number of pinholes yielded images with less artifact. The results of the simulations with the myocardial phantom showed that more than eight pinholes could yield an accurate distribution of activity when the source was distributed only in the myocardium. The results of the simulations confirmed that more than eight pinholes for each detector were required to reconstruct an artifact free image in the triple-head SPECT system for imaging of brain and myocardium.

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

    PubMed

    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.

  14. Adherence to Bergmann's rule by lizards may depend on thermoregulatory mode: support from a nocturnal gecko.

    PubMed

    Penniket, Sophie; Cree, Alison

    2015-06-01

    Bergmann's rule predicts an increase in body size with decreasing environmental temperature; however, the converse pattern has been found in the majority of lizards studied to date. For these ectotherms, small body size may provide thermal benefits (rapid heat uptake when basking), which would be highly advantageous in cold environments. Yet such an advantage may not exist in nocturnal lizards (which do not avidly bask), in which Bergmann's rule has not been closely studied. We have examined whether the body size of a primarily nocturnal gecko, Woodworthia "Otago/Southland" changed with elevation and operative temperature (determined using physical copper models). In a laboratory study, we investigated whether thermoregulatory mode (heliothermy or thigmothermy) alters the effect of body size on heating and cooling rates. This gecko followed Bergmann's rule, thereby showing the opposite of the dominant pattern in diurnal lizards. Size at maturity, maximum size of adults and size at birth were larger at higher elevations and at lower operative temperatures. Using physical models, we found that large body size can confer thermal benefits for nocturnal lizards that remain within diurnal retreats. Bergmann's rule should not be dismissed for all lizards. Our results clearly support Bergmann's rule for at least one thigmothermic species, for which large body size may provide thermal benefits. Future studies on Bergmann's rule in lizards should consider thermoregulatory mode. We advocate that this ecogeographic rule be examined in relation to operative temperature measured at field sites. Finally, we predict that climate warming may weaken the relationship between body size and elevation in this gecko.

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

    PubMed

    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.

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

    PubMed

    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

  17. Aquatic versus terrestrial attachment: Water makes a difference

    PubMed Central

    Summers, Adam P

    2014-01-01

    Summary Animal attachment to a substrate is very different in terrestrial and aquatic environments. We discuss variations in both the forces acting to detach animals and forces of attachment. While in a terrestrial environment gravity is commonly understood as the most important detachment force, under submerged conditions gravity is nearly balanced out by buoyancy and therefore matters little. In contrast, flow forces such as drag and lift are of higher importance in an aquatic environment. Depending on the flow conditions, flow forces can reach much higher values than gravity and vary in magnitude and direction. For many of the attachment mechanisms (adhesion including glue, friction, suction and mechanical principles such as hook, lock, clamp and spacer) significant differences have to be considered under water. For example, the main principles of dry adhesion, van der Waals forces and chemical bonding, which make a gecko stick to the ceiling, are weak under submerged conditions. Capillary forces are very important for wet adhesion, e.g., in terrestrial beetles or flies, but usually do not occur under water. Viscous forces are likely an important contributor to adhesion under water in some mobile animals such as torrent frogs and mayflies, but there are still many open questions to be answered. Glue is the dominant attachment mechanism of sessile aquatic animals and the aquatic realm presents many challenges to this mode of attachment. Viscous forces and the lack of surface tension under submerged conditions also affect frictional interactions in the aquatic environment. Moreover, the limitation of suction to the pressure difference at vacuum conditions can be ameliorated under water, due to the increasing pressure with water depth. PMID:25671138

  18. Aquatic versus terrestrial attachment: Water makes a difference.

    PubMed

    Ditsche, Petra; Summers, Adam P

    2014-01-01

    Animal attachment to a substrate is very different in terrestrial and aquatic environments. We discuss variations in both the forces acting to detach animals and forces of attachment. While in a terrestrial environment gravity is commonly understood as the most important detachment force, under submerged conditions gravity is nearly balanced out by buoyancy and therefore matters little. In contrast, flow forces such as drag and lift are of higher importance in an aquatic environment. Depending on the flow conditions, flow forces can reach much higher values than gravity and vary in magnitude and direction. For many of the attachment mechanisms (adhesion including glue, friction, suction and mechanical principles such as hook, lock, clamp and spacer) significant differences have to be considered under water. For example, the main principles of dry adhesion, van der Waals forces and chemical bonding, which make a gecko stick to the ceiling, are weak under submerged conditions. Capillary forces are very important for wet adhesion, e.g., in terrestrial beetles or flies, but usually do not occur under water. Viscous forces are likely an important contributor to adhesion under water in some mobile animals such as torrent frogs and mayflies, but there are still many open questions to be answered. Glue is the dominant attachment mechanism of sessile aquatic animals and the aquatic realm presents many challenges to this mode of attachment. Viscous forces and the lack of surface tension under submerged conditions also affect frictional interactions in the aquatic environment. Moreover, the limitation of suction to the pressure difference at vacuum conditions can be ameliorated under water, due to the increasing pressure with water depth.

  19. Salmonellae and other enteropathogenic bacteria in the intestines of wall geckos in Nigeria.

    PubMed

    Gugnani, H C; Oguike, J U; Sakazaki, R

    1986-01-01

    The aerobic bacterial flora of the intestine of 150 wall geckos (Hemidactylus brookei) was investigated. A variety of bacteria was recovered including 35 isolates of Salmonella and several other species of Enterobacteriaceae, viz. Shigella sonnei - 2, Edwardsiella tarda - 4, Enterobacter spp - 8, Citrobacter freudii - 3, Serratia marcescens - 3, Proteus spp - 35, Klebsiella pneumoniae - 13, and Escherichia coli - 17, isolates. Eight Salmonella serotypes were identified, the predominant ones being S. hvittingfoss and S. typhimurium. The significance of these findings for the spread of human enteropathogens is discussed.

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

    PubMed

    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

  1. A new species of gecko from arid inland regions of eastern Australia (Diplodactylus; Diplodactylidae).

    PubMed

    Couper, Patrick J; Oliver, Paul M

    2016-03-24

    We describe a new species of small terrestrial gecko in the genus Diplodactylus from inland regions of western Queensland and New South Wales, Australia. Diplodactylus ameyi sp. nov. can be distinguished from its congeners in the Diplodactylus conspicillatus species-group by its relatively large size, bulbous tail which lacks an acute attenuated extension at tip, small first labial scale and comparatively robust head morphology (which includes a broadly rounded snout and no well-defined canthus rostralis). Related populations from eastern and central Queensland currently referred to D. platyurus include further deeply divergent lineages but additional material is required to resolve systematic boundaries in this region.

  2. Adhesion mechanism of a gecko-inspired oblique structure with an adhesive tip for asymmetric detachment

    NASA Astrophysics Data System (ADS)

    Sekiguchi, Yu; Takahashi, Kunio; Sato, Chiaki

    2015-12-01

    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.

  3. A new Bent-toed gecko (Squamata: Gekkonidae) from the Mekongga Mountains, South East Sulawesi, Indonesia.

    PubMed

    Riyanto, Awal; Kurniati, Hellen; Engilis, Andrew

    2016-05-05

    We describe Cyrtodactylus hitchi sp. nov., a new species of Bent-toed Gecko from montane forests in the Mekongga Mountains, South East Sulawesi, Indonesia. Although we cannot speculate about relationships, morphologically it shares several traits with C. batik, a large species known only from Mount Tompotika near the tip of Sulawesi's Eastern Peninsula. The following unique combination of characters distinguishes it from all other congeners: absence of precloacal groove, absence of precloacal and femoral pores, absence of enlarged femoral scales, no abrupt contact between large and small postfemoral scales, 18-20 lamellae under the fourth toes, and transversely enlarged, median subcaudal scales arranged in a single row.

  4. Geckoprinting: assembly of microelectronic devices on unconventional surfaces by transfer printing with isolated gecko setal arrays.

    PubMed

    Jeong, Jaeyoung; Kim, Juho; Song, Kwangsun; Autumn, Kellar; Lee, Jongho

    2014-10-06

    Developing electronics in unconventional forms provides opportunities to expand the use of electronics in diverse applications including bio-integrated or implanted electronics. One of the key challenges lies in integrating semiconductor microdevices onto unconventional substrates without glue, high pressure or temperature that may cause damage to microdevices, substrates or interfaces. This paper describes a solution based on natural gecko setal arrays that switch adhesion mechanically on and off, enabling pick and place manipulation of thin microscale semiconductor materials onto diverse surfaces including plants and insects whose surfaces are usually rough and irregular. A demonstration of functional 'geckoprinted' microelectronic devices provides a proof of concept of our results in practical applications.

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

    PubMed

    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.

  6. Social attachments and traumatic stress

    PubMed Central

    Bryant, Richard A.

    2016-01-01

    The extent to which we engage with our social world has been central to our survival as a species and, accordingly, is relevant to how we cope with trauma and adversity. This review summarises current knowledge about the importance of social connections from an evolutionary perspective, as well as integrating this with a discussion of prevailing attachment theories. Experimental research supporting the potential benefit of attachments for managing adversity are presented, along with a review of how these benefits are moderated by individual differences in attachment style. The potential impact of trauma on attachment systems, and the manner in which this can compound trauma stress is discussed. Finally, a broader overview of social network analysis is introduced and it is proposed that a more sociocentric framework of trauma response would promote a fuller understanding of how social processes moderate trauma response. PMID:26996531

  7. Facilitating attachment after international adoption.

    PubMed

    Murphy, Natalie L

    2009-01-01

    Americans have increasingly turned to international adoption (IA) as an alternative way to build a family. Unfortunately, IA families are often being developed under conditions of loss, and sometimes these families struggle to form healthy attachments to each other. Disordered attachment (the failure to form a reciprocal, loving bond between parent and child) can occur, and can have devastating consequences. In some instances, IA children have been relinquished into state foster care systems; other families simply struggle for years caring for a developmentally delayed child who appears to have no emotion for his/her adoptive family. Nurses are likely to have contact with IA families and can use their education about attachment and bonding to help facilitate attachment in these developing families. Swanson's caring theory provides a clinically useful guide to meet this need.

  8. Analysis of the effects of firing Orbiter primary reaction control system jets with an attached truss structure

    NASA Technical Reports Server (NTRS)

    Kaszubowski, M.; Raney, J. P.

    1986-01-01

    A study was conducted to determine the dynamic effects of firing the orbiter primary reaction control jets during assembly of protoflight space station structure. Maximum longeron compressive load was calculated as a function of jet pulse time length, number of jet pulses, and total torque imposed by the reaction control jets. The study shows that it is possible to fire selected jets to achieve a pitch maneuver without causing failure of the attached structure.

  9. Little and large: body size and genetic clines in a New Zealand gecko (Woodworthia maculata) along a coastal transect

    PubMed Central

    Fitness, Josephine; Hitchmough, Rodney A; Morgan-Richards, Mary

    2012-01-01

    Clinal variation can result from primary differentiation or secondary contact and determining which of these two processes is responsible for the existence of a cline is not a trivial problem. Samples from a coastal transect of New Zealand geckos (Woodworthia maculata) identified for the first time a body size cline 7–10 km wide. The larger geckos are almost twice the mass of the small adult geckos. Clines in allele and haplotype frequency were found at two of the four genetic loci examined. Estimated width of the morphological cline was concordant with neither the narrower mtDNA cline (3–7 m) nor the wider nuclear cline (RAG-2; 34–42 km), and cline centers were not coincident. Although the body size cline is narrow compared to the entire range of the species, it is 2–3 orders of magnitude greater than estimates of dispersal distance per generation for these geckos. No evidence of assortative mating, nor of hybrid disadvantage was identified, thus there is little evidence to infer that endogenous selection is maintaining a hybrid zone. We cannot distinguish secondary contact from primary origin of this body size cline but conclude that secondary contact is likely due to the occurrence of mtDNA haplotypes from three distinct clades within the coastal transect and the presence of two frequency clines within this region. PMID:22423323

  10. Adaptive radiation in Lesser Antillean lizards: molecular phylogenetics and species recognition in the Lesser Antillean dwarf gecko complex, Sphaerodactylus fantasticus.

    PubMed

    Thorpe, R S; Jones, A G; Malhotra, A; Surget-Groba, Y

    2008-03-01

    The time associated with speciation varies dramatically among lower vertebrates. The nature and timing of divergence is investigated in the fantastic dwarf gecko Sphaerodactylus fantasticus complex, a nominal species that occurs on the central Lesser Antillean island of Guadeloupe and adjacent islands and islets. This is compared to the divergence in the sympatric anole clade from the Anolis bimaculatus group. A molecular phylogenetic analysis of numerous gecko populations from across these islands, based on three mitochondrial DNA genes, reveals several monophyletic groups occupying distinct geographical areas, these being Les Saintes, western Basse Terre plus Dominica, eastern Basse Terre, Grand Terre, and the northern and eastern islands (Montserrat, Marie Galante, Petite Terre, Desirade). Although part of the same nominal species, the molecular divergence within this species complex is extraordinarily high (27% patristic distance between the most divergent lineages) and is compatible with this group occupying the region long before the origin of the younger island arc. Tests show that several quantitative morphological traits are correlated with the phylogeny, but in general the lineages are not uniquely defined by these traits. The dwarf geckos show notably less nominal species-level adaptive radiation than that found in the sympatric southern clade of Anolis bimculatus, although both appear to have occupied the region for a broadly similar period of time. Nevertheless, the dwarf gecko populations on Les Saintes islets are the most morphologically distinct and are recognized as a full species (Sphaerodactylus phyzacinus), as are anoles on Les Saintes (Anolis terraealtae).

  11. Developmental stages of the climbing gecko Tarentola annularis with special reference to the claws, pad lamellae, and subdigital setae.

    PubMed

    Khannoon, Eraqi R

    2015-07-01

    Studying the in ovo mode of development of squamates has the advantage of allowing easy access to embryos without surgically compromising gravid females. Despite the non-ophidian squamates being a very diverse lineage of reptiles, embryonic tables for individuals of this group are very few. Here, I present the first in ovo embryonic table for a basal multi-scansored, pad-bearing gecko, Tarentola annularis. In this gecko, only the III and IV digits bear claws. Eleven embryonic stages are described based on chronological development of morphological characteristics. In contrast to other previously studied geckos, this species exhibits a longer incubation period. Comparison with other squamates, embryonic development of T. annularis is an indicative of a conserved developmental strategy. Interestingly, the clawless digits of this gecko do exhibit claws during the first half of embryonic development. Thus, regression of claws in these digits could be an advantage of studying this particular taxon, as it raises the question, to be answered in future study, of which mechanisms could be responsible for such claw regression. Before hatching, the outer periderm layer sloughs revealing the functional setae. The present study provides not only a model for pentadactyl limbs and digit development, but also an example of a unique developmental phenomenon, as represented by claw regression.

  12. Spatio-temporal gait characteristics of level and vertical locomotion in a ground-dwelling and a climbing gecko.

    PubMed

    Zaaf, A; Van Damme, R; Herrel, A; Aerts, P

    2001-04-01

    The effects of incline (vertical versus horizontal) on spatio-temporal gait characteristics (stride and step length, frequency, duty factor, degree of sprawling) were measured over a range of speeds in a ground-dwelling (Eublepharis macularius) and a climbing (Gekko gecko) species of gecko. Surprisingly, the climbing species also performs very well when moving on the horizontal substratum. In the present experiments, climbing speeds ranged from 0.6 to 1.2 m s(-1), whereas speeds for level locomotion were between 0.6 and 1.8 m s(-1). In contrast, the vertical climbing capacities of the ground-dweller are limited (speeds below 0.1 m s(-1 )versus level speeds between 0.2 and 1.1 m s(-1)). In general, we demonstrate that very little adjustment in gait characteristics is made by either species when they are forced to move on their non-habitual substratum. Moreover, gait characteristics differ little between the species despite the clear differences in ecological niche. Higher level or climbing speeds are realized mainly (or exclusively in the case of level locomotion in G. gecko) by increasing stride frequency. Stride lengths and duty factors vary with speed in the ground-dweller, but not in the climbing species. Step length and the degree of sprawling are speed-independent (except for hind-limb sprawling in G. gecko on the level). It is argued that this common strategy suits climbing (fixed spatial variables, no floating phases) rather than level locomotion.

  13. The guest playing host: colonization of the introduced Mediterranean gecko, Hemidactylus turcicus, by helminth parasites in southeastern Louisiana.

    PubMed

    Criscione, C D; Font, W F

    2001-12-01

    Parasite surveys of exotic hosts offer the opportunity to examine parasite colonization on different scales (i.e., host individual, host population, host species, and new geographic locality). Ten helminths (Macracanthorhynchus ingens, Mesocestoides lineatus, Oochoristica javaensis, Haematoloechus varioplexus, Mesocoelium monas, Telorchis corti, Cosmocercoides variabilis, Oswaldocruzia leidyi, Skrjabinoptera sp., and a larval acuariid nematode) were recovered from the exotic Mediterranean gecko Hemidactylus turcicus, in southeastern Louisiana. Only 1 exotic parasite, O. javaensis, colonized a new geographic locality, but 7 local helminths colonized a new host species. Helminth communities of H. turcicus were similar in structure to what has been hypothesized or observed for lizards. Thus, communities were composed of generalists and were depauperate (i.e., colonization of individual geckos or host populations was rare for most of the helminths); however, there was significant variation in community structure among local habitats. Although the gecko's behavioral and physiological attributes predict colonization by monoxenous helminths, only 2, C. variabilis and O. leidyi, were recovered. Eight heteroxenous helminths, 2 of which (the acuariid and O. javaensis) were the most widely distributed and abundant, were the better colonizers. The gecko's generalist diet may have exposed it to a diverse parasite fauna and thus been important in determining the helminths that could colonize.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Fine-Scale Genetic Structure Arises during Range Expansion of an Invasive Gecko

    PubMed Central

    Short, Kristen Harfmann; Petren, Kenneth

    2011-01-01

    Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts. PMID:22053186

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

    PubMed

    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.

  17. Removal mechanisms of dew via self-propulsion off the gecko skin

    PubMed Central

    Watson, Gregory S.; Schwarzkopf, Lin; Cribb, Bronwen W.; Myhra, Sverre; Gellender, Marty; Watson, Jolanta A.

    2015-01-01

    Condensation resulting in the formation of water films or droplets is an unavoidable process on the cuticle or skin of many organisms. This process generally occurs under humid conditions when the temperature drops below the dew point. In this study, we have investigated dew conditions on the skin of the gecko Lucasium steindachneri. When condensation occurs, we show that small dew drops, as opposed to a thin film, form on the lizard's scales. As the droplets grow in size and merge, they can undergo self-propulsion off the skin and in the process can be carried away a sufficient distance to freely engage with external forces. We show that factors such as gravity, wind and fog provide mechanisms to remove these small droplets off the gecko skin surface. The formation of small droplets and subsequent removal from the skin may aid in reducing microbial contact (e.g. bacteria, fungi) and limit conducive growth conditions under humid environments. As well as providing an inhospitable microclimate for microorganisms, the formation and removal of small droplets may also potentially aid in other areas such as reduction and cleaning of some surface contaminants consisting of single or multiple aggregates of particles. PMID:25762647

  18. Removal mechanisms of dew via self-propulsion off the gecko skin.

    PubMed

    Watson, Gregory S; Schwarzkopf, Lin; Cribb, Bronwen W; Myhra, Sverre; Gellender, Marty; Watson, Jolanta A

    2015-04-06

    Condensation resulting in the formation of water films or droplets is an unavoidable process on the cuticle or skin of many organisms. This process generally occurs under humid conditions when the temperature drops below the dew point. In this study, we have investigated dew conditions on the skin of the gecko Lucasium steindachneri. When condensation occurs, we show that small dew drops, as opposed to a thin film, form on the lizard's scales. As the droplets grow in size and merge, they can undergo self-propulsion off the skin and in the process can be carried away a sufficient distance to freely engage with external forces. We show that factors such as gravity, wind and fog provide mechanisms to remove these small droplets off the gecko skin surface. The formation of small droplets and subsequent removal from the skin may aid in reducing microbial contact (e.g. bacteria, fungi) and limit conducive growth conditions under humid environments. As well as providing an inhospitable microclimate for microorganisms, the formation and removal of small droplets may also potentially aid in other areas such as reduction and cleaning of some surface contaminants consisting of single or multiple aggregates of particles.

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

    PubMed

    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.

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

    PubMed

    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.

  1. Ontogeny of Metabolic Rate and Red Blood Cell Size in Eyelid Geckos: Species Follow Different Paths

    PubMed Central

    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. PMID:23705003

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

    PubMed

    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.

  3. A new genus of miniaturized and pug-nosed gecko from South America (Sphaerodactylidae: Gekkota)

    PubMed Central

    Gamble, Tony; Daza, Juan D; Colli, Guarino R; Vitt, Laurie J; Bauer, Aaron M

    2011-01-01

    Sphaerodactyl geckos comprise five genera distributed across Central and South America and the Caribbean. We estimated phylogenetic relationships among sphaerodactyl genera using both separate and combined analyses of seven nuclear genes. Relationships among genera were incongruent at different loci and phylogenies were characterized by short, in some cases zero length, internal branches and poor phylogenetic support at most nodes. We recovered a polyphyletic Coleodactylus, with Coleodactylus amazonicus being deeply divergent from the remaining Coleodactylus species sampled. The C. amazonicus lineage possessed unique codon deletions in the genes PTPN12 and RBMX while the remaining Coleodactylus species had unique codon deletions in RAG1. Topology tests could not reject a monophyletic Coleodactylus, but we show that short internal branch lengths decreased the accuracy of topology tests because there were not enough data along short branches to support one phylogenetic hypothesis over another. Morphological data corroborated results of the molecular phylogeny, with Coleodactylus exhibiting substantial morphological heterogeneity. We identified a suite of unique craniofacial features that differentiate C. amazonicus not only from other Coleodactylus species, but also from all other geckos. We describe this novel sphaerodactyl lineage as a new genus, Chatogekko gen. nov. We present a detailed osteology of Chatogekko, characterizing osteological correlates of miniaturization that provide a framework for future studies in sphaerodactyl systematics and biology. PMID:22125341

  4. Assessment of the GECKO-A modeling tool using chamber observations for C12 alkanes

    NASA Astrophysics Data System (ADS)

    Aumont, B.; La, S.; Ouzebidour, F.; Valorso, R.; Mouchel-Vallon, C.; Camredon, M.; Lee-Taylor, J. M.; Hodzic, A.; Madronich, S.; Yee, L. D.; Loza, C. L.; Craven, J. S.; Zhang, X.; Seinfeld, J.

    2013-12-01

    Secondary Organic Aerosol (SOA) production and ageing is the result of atmospheric oxidation processes leading to the progressive formation of organic species with higher oxidation state and lower volatility. Explicit chemical mechanisms reflect our understanding of these multigenerational oxidation steps. Major uncertainties remain concerning the processes leading to SOA formation and the development, assessment and improvement of such explicit schemes is therefore a key issue. The development of explicit mechanism to describe the oxidation of long chain hydrocarbons is however a challenge. Indeed, explicit oxidation schemes involve a large number of reactions and secondary organic species, far exceeding the size of chemical schemes that can be written manually. The chemical mechanism generator GECKO-A (Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere) is a computer program designed to overcome this difficulty. GECKO-A generates gas phase oxidation schemes according to a prescribed protocol assigning reaction pathways and kinetics data on the basis of experimental data and structure-activity relationships. In this study, we examine the ability of the generated schemes to explain SOA formation observed in the Caltech Environmental Chambers from various C12 alkane isomers and under high NOx and low NOx conditions. First results show that the model overestimates both the SOA yields and the O/C ratios. Various sensitivity tests are performed to explore processes that might be responsible for these disagreements.

  5. Tertiary climate change and the diversification of the Amazonian gecko genus Gonatodes (Sphaerodactylidae, Squamata).

    PubMed

    Gamble, Tony; Simons, Andrew M; Colli, Guarino R; Vitt, Laurie J

    2008-01-01

    The genus Gonatodes is a monophyletic group of small-bodied, diurnal geckos distributed across northern South America, Central America, and the Caribbean. We used fragments of three nuclear genes (RAG2, ACM4, and c-mos) and one mitochondrial gene (16S) to estimate phylogenetic relationships among Amazonian species of Gonatodes. We used Penalized Likelihood to estimate timing of diversification in the genus. Most cladogenesis occurred in the Oligocene and early Miocene and coincided with a burst of diversification in other South American animal groups including mollusks, birds, and mammals. The Oligocene and early Miocene were periods dominated by dramatic climate change and Andean orogeny and we suggest that these factors drove the burst of cladogenesis in Gonatodes geckos as well as other taxa. A common pattern in Amazonian taxa is a biogeographic split between the eastern and western Amazon basin. We observed two clades with this spatial distribution, although large differences in timing of divergence between the east-west taxon pairs indicate that these divergences were not the result of a common vicariant event.

  6. Fine-scale genetic structure arises during range expansion of an invasive gecko.

    PubMed

    Short, Kristen Harfmann; Petren, Kenneth

    2011-01-01

    Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Molecular phylogenetic and dating analyses using mitochondrial DNA sequences of eyelid geckos (Squamata: Eublepharidae).

    PubMed

    Jonniaux, Pierre; Kumazawa, Yoshinori

    2008-01-15

    Mitochondrial DNA sequences of approximately 2.3 kbp including the complete NADH dehydrogenase subunit 2 gene and its flanking genes, as well as parts of 12S and 16S rRNA genes were determined from major species of the eyelid gecko family Eublepharidae sensu [Kluge, A.G. 1987. Cladistic relationships in the Gekkonoidea (Squamata, Sauria). Misc. Publ. Mus. Zool. Univ. Michigan 173, 1-54.]. In contrast to previous morphological studies, phylogenetic analyses based on these sequences supported that Eublepharidae and Gekkonidae form a sister group with Pygopodidae, raising the possibility of homoplasious character change in some key features of geckos, such as reduction of movable eyelids and innovation of climbing toe pads. The phylogenetic analyses also provided a well-resolved tree for relationships between the eublepharid species. The Bayesian estimation of divergence times without assuming the molecular clock suggested the Jurassic divergence of Eublepharidae from Gekkonidae and radiations of most eublepharid genera around the Cretaceous. These dating results appeared to be robust against some conditional changes for time estimation, such as gene regions used, taxon representation, and data partitioning. Taken together with geological evidence, these results support the vicariant divergence of Eublepharidae and Gekkonidae by the breakup of Pangea into Laurasia and Gondwanaland, and recent dispersal of two African eublepharid genera from Eurasia to Africa after these landmasses were connected in the Early Miocene.

  9. Special Attachments. Module 19.

    ERIC Educational Resources Information Center

    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…

  10. Attachment over Time.

    ERIC Educational Resources Information Center

    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.…

  11. A gecko skin micro/nano structure - A low adhesion, superhydrophobic, anti-wetting, self-cleaning, biocompatible, antibacterial surface.

    PubMed

    Watson, Gregory S; Green, David W; Schwarzkopf, Lin; Li, Xin; Cribb, Bronwen W; Myhra, Sverre; Watson, Jolanta A

    2015-07-01

    Geckos, and specifically their feet, have attracted significant attention in recent times with the focus centred around their remarkable adhesional properties. Little attention however has been dedicated to the other remaining regions of the lizard body. In this paper we present preliminary investigations into a number of notable interfacial properties of the gecko skin focusing on solid and aqueous interactions. We show that the skin of the box-patterned gecko (Lucasium sp.) consists of dome shaped scales arranged in a hexagonal patterning. The scales comprise of spinules (hairs), from several hundred nanometres to several microns in length, with a sub-micron spacing and a small radius of curvature typically from 10 to 20 nm. This micro and nano structure of the skin exhibited ultralow adhesion with contaminating particles. The topography also provides a superhydrophobic, anti-wetting barrier which can self clean by the action of low velocity rolling or impacting droplets of various size ranges from microns to several millimetres. Water droplets which are sufficiently small (10-100 μm) can easily access valleys between the scales for efficient self-cleaning and due to their dimensions can self-propel off the surface enhancing their mobility and cleaning effect. In addition, we demonstrate that the gecko skin has an antibacterial action where Gram-negative bacteria (Porphyromonas gingivalis) are killed when exposed to the surface however eukaryotic cell compatibility (with human stem cells) is demonstrated. The multifunctional features of the gecko skin provide a potential natural template for man-made applications where specific control of liquid, solid and biological contacts is required. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  12. A novel universal real-time PCR system using the attached universal duplex probes for quantitative analysis of nucleic acids

    PubMed Central

    Yang, Litao; Liang, Wanqi; Jiang, Lingxi; Li, Wenquan; Cao, Wei; Wilson, Zoe A; Zhang, Dabing

    2008-01-01

    Background Real-time PCR techniques are being widely used for nucleic acids analysis, but one limitation of current frequently employed real-time PCR is the high cost of the labeled probe for each target molecule. Results We describe a real-time PCR technique employing attached universal duplex probes (AUDP), which has the advantage of generating fluorescence by probe hydrolysis and strand displacement over current real-time PCR methods. AUDP involves one set of universal duplex probes in which the 5' end of the fluorescent probe (FP) and a complementary quenching probe (QP) lie in close proximity so that fluorescence can be quenched. The PCR primer pair with attached universal template (UT) and the FP are identical to the UT sequence. We have shown that the AUDP technique can be used for detecting multiple target DNA sequences in both simplex and duplex real-time PCR assays for gene expression analysis, genotype identification, and genetically modified organism (GMO) quantification with comparable sensitivity, reproducibility, and repeatability with other real-time PCR methods. Conclusion The results from GMO quantification, gene expression analysis, genotype identification, and GMO quantification using AUDP real-time PCR assays indicate that the AUDP real-time PCR technique has been successfully applied in nucleic acids analysis, and the developed AUDP real-time PCR technique will offer an alternative way for nucleic acid analysis with high efficiency, reliability, and flexibility at low cost. PMID:18522756

  13. Neurobiology of Infant Attachment

    PubMed Central

    Moriceau, Stephanie

    2007-01-01

    A strong attachment to the caregiver is critical for survival in altricial species, including humans. While some behavioral aspects of attachment have been characterized, its neurobiology has only recently received attention. Using a mammalian imprinting model, we are assessing the neural circuitry that enables infant rats to attach quickly to a caregiver, thus enhancing survival in the nest. Specifically, the hyper-functioning noradrenergic locus coeruleus (LC) enables pups to learn rapid, robust preference for the caregiver. Conversely, a hypo-functional amygdala appears to prevent the infant from learning aversions to the caregiver. Adult LC and amygdala functional emergence correlates with sensitive period termination. This study suggests the neonatal brain is not an immature version of the adult brain but is uniquely designed to optimize attachment to the caregiver. Although human attachment may not rely on identical circuitry, the work reviewed here suggests a new conceptual framework in which to explore human attachments, particularly attachments to abusive caregivers. PMID:16252291

  14. Attachment Theory Applied to Juvenile Sex Offending.

    ERIC Educational Resources Information Center

    Goodrow, Kenneth K.; Lim, Mee-Gaik

    1998-01-01

    Attachment theory is applied to identify systemic patterns encouraging juveniles to commit sexual offenses. The role of the helping system in perpetuating offenses is reviewed. The priority of family integrity and the role of professionals in breaking cycles of abuse and repairing earlier destructive emotional attachments are discussed. (EMK)

  15. In Vivo Measurement of Mesokinesis in Gekko gecko: The Role of Cranial Kinesis during Gape Display, Feeding and Biting

    PubMed Central

    Montuelle, Stéphane J.; Williams, Susan H.

    2015-01-01

    Cranial kinesis refers to movements of skeletal sub-units relative to one another at mobile sutures within the skull. The presence and functional significance of cranial kinesis has been investigated in various vertebrates, with much of our understanding coming from comparative studies and manipulation of ligamentous specimens. Drawing on these studies, cranial kinesis in lizards has been modeled as a four-bar linkage system involving streptostyly (rotation of the quadrate), hypokinesis (dorsoventral flexion and extension of the palato-maxillary sub-unit), mesokinesis (dorsoventral flexion and extension of the snout at the fronto-parietal suture) and metakinesis (sliding movements between parietal and supraocciptal bones). In vivo studies, although limited, suggest that cranial kinesis serves an important role during routine behaviors such as feeding. Here, we use X-ray Reconstruction Of Moving Morphology to further quantify mesokinesis in vivo in Gekko gecko during three routine behaviors: gape display, biting and post-ingestion feeding. During gape display, the snout rotates dorsally above rest position, with mesokinesis accounting for a 10% increase in maximum gape over that achieved solely by the depression of the lower jaw. During defensive biting, the snout rotates ventrally below rest position to participate in gape closure. Finally, ventroflexion of the snout also occurs during post-ingestion feeding, accounting for 42% of gape closure during intra-oral transport, 86% during puncture-crushing, and 61% during pharyngeal packing. Mesokinesis thus appears to facilitate prey puncturing by allowing the snout to rotate ventrally so that the upper teeth pierce the prey item, thus limiting the need for large movements of the lower jaw. This is suggested to maintain a firm grip on the prey and reduce the possibility of prey escape. More generally, this study demonstrates that mesokinesis is a key component of defensive biting and gape display behaviors, as well as

  16. In Vivo Measurement of Mesokinesis in Gekko gecko: The Role of Cranial Kinesis during Gape Display, Feeding and Biting.

    PubMed

    Montuelle, Stéphane J; Williams, Susan H

    2015-01-01

    Cranial kinesis refers to movements of skeletal sub-units relative to one another at mobile sutures within the skull. The presence and functional significance of cranial kinesis has been investigated in various vertebrates, with much of our understanding coming from comparative studies and manipulation of ligamentous specimens. Drawing on these studies, cranial kinesis in lizards has been modeled as a four-bar linkage system involving streptostyly (rotation of the quadrate), hypokinesis (dorsoventral flexion and extension of the palato-maxillary sub-unit), mesokinesis (dorsoventral flexion and extension of the snout at the fronto-parietal suture) and metakinesis (sliding movements between parietal and supraocciptal bones). In vivo studies, although limited, suggest that cranial kinesis serves an important role during routine behaviors such as feeding. Here, we use X-ray Reconstruction Of Moving Morphology to further quantify mesokinesis in vivo in Gekko gecko during three routine behaviors: gape display, biting and post-ingestion feeding. During gape display, the snout rotates dorsally above rest position, with mesokinesis accounting for a 10% increase in maximum gape over that achieved solely by the depression of the lower jaw. During defensive biting, the snout rotates ventrally below rest position to participate in gape closure. Finally, ventroflexion of the snout also occurs during post-ingestion feeding, accounting for 42% of gape closure during intra-oral transport, 86% during puncture-crushing, and 61% during pharyngeal packing. Mesokinesis thus appears to facilitate prey puncturing by allowing the snout to rotate ventrally so that the upper teeth pierce the prey item, thus limiting the need for large movements of the lower jaw. This is suggested to maintain a firm grip on the prey and reduce the possibility of prey escape. More generally, this study demonstrates that mesokinesis is a key component of defensive biting and gape display behaviors, as well as

  17. Functional connectivity among limbic brain areas: differential effects of incubation temperature and gonadal sex in the leopard gecko, Eublepharis macularius.

    PubMed

    Sakata, J T; Coomber, P; Gonzalez-Lima, F; Crews, D

    2000-03-01

    The neural basis of individual differences in behavior has been studied primarily by analyzing the properties of specific neural areas. However, because of the organization of the nervous system, it is also plausible that differences in behavior are mediated by differences in the interactivity or functional connectivity among brain nuclei in particular neural circuits. In the leopard gecko, Eublepharis macularius, the temperature of the egg during incubation not only determines gonadal sex, but also shapes the sociosexual behaviors, reproductive physiology, and hormone sensitivity of adult animals. In this study the effects of both incubation temperature and gonadal sex on functional connectivity among limbic brain areas were examined. Functional connectivity was assessed by analyzing covariance patterns in metabolic capacity, as revealed by quantitative cytochrome oxidase histochemistry. It was hypothesized that incubation temperature and gonadal sex affect the propensity to display aggressive or sexual behaviors by altering the functional connectivity within relevant neural circuits. The correlations of metabolic capacity between the anterior hypothalamus and both the septum and preoptic area were significant only in relatively aggressive individuals, suggesting that these circuits may regulate the phenotypic variation in aggressiveness caused by incubation temperature. The correlations between the ventromedial hypothalamus and both the dorsal ventricular ridge and septum were significant only in females, suggesting that these circuits may modulate female-typical sexual behaviors. Correlations among preoptic, hypothalamic and amygdalar areas tended to be distributed across both sexes, suggesting that there may be shared pathways underlying the expression of male-typical and female-typical behaviors. Copyright 2000 S. Karger AG, Basel

  18. Temperament and attachment disorders.

    PubMed

    Zeanah, Charles H; Fox, Nathan A

    2004-03-01

    Reviewed in this article is research on children with reactive attachment disorder (RAD) who exhibit specific patterns of socially aberrant behavior resulting from being maltreated or having limited opportunities to form selective attachments. There are no data explaining why 2 different patterns of the disorder, an emotionally withdrawn-inhibited pattern and an indiscriminate-disinhibited pattern, arise from similarly aberrant environments. In this article, we consider whether temperamental differences might contribute to the different manifestations of reactive attachment disorder (RAD) in the context of adverse environments. Although the association between attachment and temperament has been studied extensively and has been the subject of spirited debate within the field of child development, there are no extant data on the influence of temperament on the development of attachment disorders. We consider possible directions for research efforts designed to explore the biological underpinnings of the complex phenomenon of attachment disorders.

  19. Blade attachment assembly

    SciTech Connect

    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.

  20. Attachment in integrative neuroscientific perspective.

    PubMed

    Hruby, Radovan; Hasto, Jozef; Minarik, Peter

    2011-01-01

    Attachment theory is a very influential general concept of human social and emotional development, which emphasizes the role of early mother-infant interactions for infant's adaptive behavioural and stress copying strategies, personality organization and mental health. Individuals with disrupted development of secure attachment to mother/primary caregiver are at higher risk of developing mental disorders. This theory consists of the complex developmental psycho-neurobiological model of attachment and emerges from principles of psychoanalysis, evolutionary biology, cognitive-developmental psychology, ethology, physiology and control systems theory. The progress of modern neuroscience enables interpretation of neurobiological aspects of the theory as multi-level neural interactions and functional development of important neural structures, effects of neuromediattors, hormones and essential neurobiological processes including emotional, cognitive, social interactions and the special key role of mentalizing. It has multiple neurobiological, neuroendocrine, neurophysiological, ethological, genetic, developmental, psychological, psychotherapeutic and neuropsychiatric consequences and is a prototype of complex neuroscientific concept as interpretation of modern integrated neuroscience.

  1. Automatic Activation of Attachment-Related Goals

    PubMed Central

    Gillath, Omri; Mikulincer, Mario; Fitzsimons, Grainne M.; Shaver, Phillip R.; Schachner, Dory A.; Bargh, John A.

    2009-01-01

    When people encounter threats, their attachment systems are activated and they become motivated to seek protection and support through proximity to their attachment figures. Theoretically, therefore, mental representations of attachment figures should be associated with goals related to attaining proximity and safety. The present studies explore this idea by examining the effects of a person’s chronic attachment style and exposure to a particular attachment figure’s name on the automatic activation of attachment-related goals. Studies 1 and 2 examine effects of exposure to the name of a security-providing attachment figure on willingness to self-disclose and seek support (two behaviors related to gaining proximity). Study 3 examines how exposure to names of different relationship partners (with whom a participant has felt secure, anxious, or avoidant) affects the mental accessibility of attachment-related goal words. Taken together, the studies support the idea that mental representations of attachment figures are associated with attachment-related goals. PMID:16963608

  2. Structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Pirnat, Miha; Čepon, Gregor; Boltežar, Miha

    2014-03-01

    In this paper three approaches are combined to develop a structural-acoustic model of a rectangular plate-cavity system with an attached distributed mass and internal sound source. The first approach results from a recently presented analysis based on the Rayleigh-Ritz method and is used to circumvent the difficulties in obtaining the natural frequencies and mode shapes of a plate with an attached, distributed mass. Furthermore, different plate boundary conditions can be accommodated. The resulting mode shapes are defined as continuous functions; this is advantageous as they can be directly used in the second approach, i.e., the classic modal-interaction approach in order to obtain the coupled equations of the system. Finally, in the third approach a group of point sources emitting a pressure pulse in the time domain is used to model an internal sound source. For the validation of the developed model an experiment was conducted in two configurations using a simply supported aluminium plate and a clamped plate coupled with a plexiglas box containing a loudspeaker. Good agreement was found between the analytical and experimental data.

  3. Optimizing electrode-attached redox-peptide systems for kinetic characterization of protease action on immobilized substrates. Observation of dissimilar behavior of trypsin and thrombin enzymes.

    PubMed

    Anne, Agnès; Chovin, Arnaud; Demaille, Christophe

    2012-06-12

    In this work, we experimentally address the issue of optimizing gold electrode attached ferrocene (Fc)-peptide systems for kinetic measurements of protease action. Considering human α-thrombin and bovine trypsin as proteases of interest, we show that the recurring problem of incomplete cleavage of the peptide layer by these enzymes can be solved by using ultraflat template-stripped gold, instead of polished polycrystalline gold, as the Fc-peptide bearing electrode material. We describe how these fragile surfaces can be mounted in a rotating disk configuration so that enzyme mass transfer no longer limits the overall measured cleavage kinetics. Finally, we demonstrate that, once the system has been optimized, in situ real-time cyclic voltammetry monitoring of the protease action can yield high-quality kinetic data, showing no sign of interfering effects. The cleavage progress curves then closely match the Langmuirian variation expected for a kinetically controlled surface process. Global fit of the progress curves yield accurate values of the peptide cleavage rate for both trypsin and thrombin. It is shown that, whereas trypsin action on the surface-attached peptide closely follows Michaelis-Menten kinetics, thrombin displays a specific and unexpected behavior characterized by a nearly enzyme-concentration-independent cleavage rate in the subnanomolar enzyme concentration range. The reason for this behavior has still to be clarified, but its occurrence may limit the sensitivity of thrombin sensors based on Fc-peptide layers.

  4. Visual pigments and spectral sensitivity of the diurnal gecko Gonatodes albogularis.

    PubMed

    Ellingson, J M; Fleishman, L J; Loew, E R

    1995-11-01

    The visual pigments and oil droplets in the retina of the diurnal gecko Gonatodes albogularis were examined microspectrophotometrically, and the spectral sensitivity under various adapting conditions was recorded using electrophysiological responses. Three classes of visual pigments were identified, with lambda max at about 542, 475, and 362 nm. Spectral sensitivity functions revealed a broad range of sensitivity, with a peak at approximately 530-540 nm. The cornea and oil droplets were found to be transparent across a range from 350-700 nm, but the lens absorbed short wavelength light below 450 nm. Despite the filtering effect of the lens, a secondary peak in spectral sensitivity to ultraviolet wavelengths was found. These results suggest that G. albogularis does possess the visual mechanisms for discrimination of the color pattern of conspecifics based on either hue or brightness. These findings are discussed in terms of the variation in coloration and social behavior of Gonatodes.

  5. A new insular species of Rock Gecko (Cnemaspis Boulenger) from Pulau Langkawi, Kedah, Peninsular Malaysia.

    PubMed

    Grismer, L Lee; Wood, P L Jr; Quah, Evan S H; Anuar, Shahrul; Ngadi, Ehwan; Ahmad, Norhayati

    2015-07-10

    A new, diminutive species of Rock Gecko Cnemaspis mahsuriae sp. nov. of the affinis group, is described from Gunung Raya on Pulau Langkawi, Kedah, Peninsular Malaysia and is differentiated from all other species in the affinis group by having a unique combination of characters including a maximum SVL of 36.6 mm; keeled subtibials and ventrals; 21-24 paravertebral tubercles; no tubercles in the lateral caudal furrows; caudal tubercles not encircling tail; no precloacal pores; 23-26 subdigital lamellae on the fourth toe; no white ocelli in the shoulder region; no yellow postscapular band; and faint yellow bars on the flanks. Cnemaspis mahsuriae sp. nov. is a forest-dwelling species living in close sympatry or paraptry with the insular endemic C. roticanai Grismer & Chan. The Langkawi Archipelago harbors a unique mix of Malaysian and Indochinese taxa and the frequency of new discoveries from this group of islands is increasing.

  6. A new Bent-toed Gecko (Squamata: Gekkonidae: Cyrtodactylus) from Phetchaburi Province, Thailand.

    PubMed

    Pauwels, Olivier S G; Sumontha, Montri; Bauer, Aaron M

    2016-03-09

    A new Bent-toed Gecko, Cyrtodactylus phetchaburiensis sp. nov. is described from the Tha Yang District of Phetchaburi Province, western Thailand. It is a medium-sized Cyrtodactylus (SVL to at least 63.2 mm), with small, mostly keeled tubercles in 20 regular longitudinal rows on dorsum; 33 scales across mid-venter between lowest rows of flank tubercles; enlarged row of femoral scales present; five precloacal pores in male, femoral pores and precloacal groove absent; 5-6 broad basal lamellae and 11 narrow distal lamellae beneath digit IV of pes; and a single median row of transversely enlarged subcaudal scales present. It has a dorsal colour pattern of large, dark, diffusely-edged markings on a fawn background and a pair of dark scapular patches. The species is a member of the Central Indochinese (Thai-Myanmar) clade of Cyrtodactylus and is most closely related to C. oldhami (Theobald), from which it differs in colour pattern.

  7. Investigating SOA from alpha-pinene ozonolysis with the GECKO modeling tool.

    NASA Astrophysics Data System (ADS)

    Lee-Taylor, J. M.; Madronich, S.; Aumont, B.; Lawler, M. J.; Smith, J. N.; Camredon, M.

    2014-12-01

    Atmospheric oxidation of terpenes leads to a rich variety of functionalized organic molecules of vapor pressures low enough to permit their condensation on particles. GECKO-A is an explicit chemical model useful for investigating fine details of tropospheric oxidation chemistry. The TDCIMS measurement technique allows the identification of specific molecular formulae in aerosol particles. We have incorporated recent advances in alpha-pinene chemistry into the model and apply it to study alpha-pinene ozonolysis and its subsequent condensable products. We assess the degree to which particle size affects modeled aerosol chemical composition and structure from alpha-pinene ozonolysis and compare the statistical composition of the modeled aerosol to that observed by TDCIMS in chamber studies.

  8. UNSEDATED COMPUTED TOMOGRAPHY FOR DIAGNOSIS OF PELVIC CANAL OBSTRUCTION IN A LEOPARD GECKO (EUBLEPHARIS MACULARIUS).

    PubMed

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

    PubMed

    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.

  10. The complete mitochondrial genome of the Madagascar ground gecko Paroedura picta (Squamata: Gekkonidae).

    PubMed

    Starostová, Zuzana; Musilová, Zuzana

    2016-11-01

    We sequenced the complete mitochondrial genome of the Madagascar ground gecko Paroedura picta (Squamata: Gekkonidae). The mitogenome is 17 220 base pairs long and conforms to the typical vertebrate gene composition and arrangement, i.e. 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes and 1919 bp long control region. We reconstructed phylogenetic relationships of P. picta and representatives of nine other genera from the family Gekkonidae and calculated mean p-distances for all 13 protein-coding mitochondrial genes. The lowest mean p-distances were found in cytochrome oxidase subunit I and III genes (COI and COIII) indicating their usefulness for elucidating deeper phylogenetic relationships.

  11. Normal developmental stages of the Madagascar ground gecko Paroedura pictus with special reference to limb morphogenesis.

    PubMed

    Noro, Miyuki; Uejima, Asaka; Abe, Gembu; Manabe, Makoto; Tamura, Koji

    2009-01-01

    A table of developmental stages of the target species is useful for studying the development of any animal. Although tables of developmental stages have been established for several squamates, none has been published for gekkonid lizards. We have established a table of developmental stages for the Madagascar ground gecko Paroedura pictus. The table includes 27 embryonic stages from oviposition to hatching based on chronology and external morphology. The interval from oviposition to hatching is 60 days. Eleven to sixteen somites were observed at oviposition, and 5 to 6 somites were formed each day. Limb bud swellings were recognized by the third day after oviposition. After 2 weeks of incubation, the presumptive autopod was detected by carpal/tarsal cartilage formation. Cartilages in all digits were seen by 3 weeks after oviposition. Skin pigment was visible after 4 weeks incubation, and the skin color pattern was apparent 40 days after oviposition. Copyright (c) 2008 Wiley-Liss, Inc.

  12. Macroevolutionary pattern of sexual size dimorphism in geckos corresponds to intraspecific temperature-induced variation.

    PubMed

    Starostová, Z; Kubicka, L; Kratochvíl, L

    2010-04-01

    Many animal lineages exhibit allometry in sexual size dimorphism (SSD), known as 'Rensch's rule'. When applied to the interspecific level, this rule states that males are more evolutionary plastic in body size than females and that male-biased SSD increases with body size. One of the explanations for the occurrence of Rensch's rule is the differential-plasticity hypothesis assuming that higher evolutionary plasticity in males is a consequence of larger sensitivity of male growth to environmental cues. We have confirmed the pattern consistent with Rensch's rule among species of the gecko genus Paroedura and followed the ontogeny of SSD at three constant temperatures in a male-larger species (Paroedura picta). In this species, males exhibited larger temperature-induced phenotypic plasticity in final body size than females, and body size and SSD correlated across temperatures. This result supports the differential-plasticity hypothesis and points to the role phenotypic plasticity plays in generating of evolutionary novelties.

  13. Geckoprinting: assembly of microelectronic devices on unconventional surfaces by transfer printing with isolated gecko setal arrays

    PubMed Central

    Jeong, Jaeyoung; Kim, Juho; Song, Kwangsun; Autumn, Kellar; Lee, Jongho

    2014-01-01

    Developing electronics in unconventional forms provides opportunities to expand the use of electronics in diverse applications including bio-integrated or implanted electronics. One of the key challenges lies in integrating semiconductor microdevices onto unconventional substrates without glue, high pressure or temperature that may cause damage to microdevices, substrates or interfaces. This paper describes a solution based on natural gecko setal arrays that switch adhesion mechanically on and off, enabling pick and place manipulation of thin microscale semiconductor materials onto diverse surfaces including plants and insects whose surfaces are usually rough and irregular. A demonstration of functional ‘geckoprinted’ microelectronic devices provides a proof of concept of our results in practical applications. PMID:25056216

  14. Direct integration of MEMS, dielectric pumping and cell manipulation with reversibly bonded gecko adhesive microfluidics

    NASA Astrophysics Data System (ADS)

    Warnat, S.; King, H.; Wasay, A.; Sameoto, D.; Hubbard, T.

    2016-09-01

    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 µm 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 µm s-1 and 20 µm s-1.

  15. Synthesis and characterization of multiwalled carbon nanotube/IPMC actuator for imitating locomotion of gecko's toes

    NASA Astrophysics Data System (ADS)

    He, Qingsong; Yu, Min; Ding, Yan; Dai, Zhendong

    2012-04-01

    A multi-walled carbon nanotube (MCNT)/Nafion nanocomposite was fabricated by dispersion of treated MCNTs in a Nafion solution. The multi-walled carbon nanotube (MCNT) filler was prepared with the cationic surfactant cetyl trimethyl ammonium bromide. Starting from cast Nafion membranes, IPMCs were manufactured by electroless plating. The current and the blocking force were measured with an IPMC actuation testing apparatus. Compared with a bare Nafion-based IPMC, the blocking force of the new IPMC improved 1-1.4 times, and the current increased by 33%-67%. The clearly enhanced performance of the new MCNT filler-based IPMC is attributed to the well-distributed MCNTs that improved the electrical properties of the IPMC. Finally, the new IPMC was successfully employed to directly actuate gecko-inspired adhesive arrays that we fabricated by ourselves.

  16. The fourth Bent-toed Gecko of the genus Cyrtodactylus (Squamata: Gekkonidae) from Java, Indonesia.

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    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.

  19. Comparing audiological test results obtained from a sound processor attached to a Softband with direct and magnetic passive bone conduction hearing implant systems.

    PubMed

    Kara, Ahmet; Iseri, Mete; Durgut, Merve; Topdag, Murat; Ozturk, Murat

    2016-12-01

    The aim of this study was to compare audiological test results obtained from a sound processor (SP) attached to a Softband with those obtained from direct (abutment connection) bone conduction implant systems and magnetic passive bone conduction implant systems with different magnet strengths on patients implanted at our clinic. Twenty-four patients who were implanted with either an abutment or magnetic bone conduction implant system between January 2012 and December 2014 were analyzed for hearing results, such as free-field hearing thresholds, direct bone conduction hearing thresholds, and speech discrimination scores with aided and unaided conditions Both magnetic and direct osseointegrated bone conduction implant systems, as well as the Softband system, provide good hearing outcomes when compared with unaided performance; however, the abutment connection system gives better hearing thresholds in the higher frequencies. No significant difference in hearing gain was found between the Softband system, magnet 5, and magnet used by the patient. Magnetic and direct bone conduction hearing implant systems are both effective for rehabilitation of conductive and mixed hearing loss when conventional hearing aids cannot be used. However, patients with high-frequency hearing loss may be better suited to an abutment connection system if they are not satisfied with high-frequency hearing gains provided via the trial Softband system preoperatively and should be counseled accordingly.

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

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

    PubMed Central

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

    2015-01-01

    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. PMID:26063826

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

    PubMed

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

    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.

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

    PubMed

    Gilbert, Eab; Vickaryous, M K

    2017-10-04

    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. This article is protected by copyright. All rights reserved. © 2017 Wiley Periodicals, Inc.

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

    PubMed

    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.

  8. Comparison of otoacoustic emissions within gecko subfamilies: morphological implications for auditory function in lizards.

    PubMed

    Bergevin, Christopher

    2011-04-01

    Otoacoustic emissions (OAEs) are sounds emitted by the ear and provide a non-invasive probe into mechanisms underlying peripheral auditory transduction. This study focuses upon a comparison of emission properties in two phylogenetically similar pairs of gecko: Gekko gecko and Hemidactylus turcicus and Eublepharis macularius and Coleonyx variegatus. Each pair consists of two closely related species within the same subfamily, with quantitatively known morphological properties at the level of the auditory sensory organ (basilar papilla) in the inner ear. Essentially, the comparison boils down to an issue of size: how does overall body size, as well as the inner-ear dimensions (e.g., papilla length and number of hair cells), affect peripheral auditory function as inferred from OAEs? Estimates of frequency selectivity derived from stimulus-frequency emissions (emissions evoked by a single low-level tone) indicate that tuning is broader in the species with fewer hair cells/shorter papilla. Furthermore, emissions extend outwards to higher frequencies (for similar body temperatures) in the species with the smaller body size/narrower interaural spacing. This observation suggests the smaller species have relatively improved high-frequency sensitivity, possibly related to vocalizations and/or aiding azimuthal sound localization. For one species (Eublepharis), emissions were also examined in both juveniles and adults. Qualitatively similar emission properties in both suggests that inner-ear function is adult like soon after hatching and that external body size (e.g., middle-ear dimensions and interaural spacing) has a relatively small impact upon emission properties within a species.

  9. Interactions between Hair Cells Shape Spontaneous Otoacoustic Emissions in a Model of the Tokay Gecko's Cochlea

    PubMed Central

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

    2010-01-01

    Background 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. Methodology and Principal Findings 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. Conclusions and Significance 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. PMID:20559557

  10. Durability Evaluation of a Thin Film Sensor System With Enhanced Lead Wire Attachments on SiC/SiC Ceramic Matrix Composites

    NASA Technical Reports Server (NTRS)

    Lei, Jih-Fen; Kiser, J. Douglas; Singh, Mrityunjay; Cuy, Mike; Blaha, Charles A.; Androjna, Drago

    2000-01-01

    An advanced thin film sensor system instrumented on silicon carbide (SiC) fiber reinforced SiC matrix ceramic matrix composites (SiC/SiC CMCs), was evaluated in a Mach 0.3 burner rig in order to determine its durability to monitor material/component surface temperature in harsh environments. The sensor system included thermocouples in a thin film form (5 microns thick), fine lead wires (75 microns diameter), and the bonds between these wires and the thin films. Other critical components of the overall system were the heavy, swaged lead wire cable (500 microns diameter) that contained the fine lead wires and was connected to the temperature readout, and ceramic attachments which were bonded onto the CMCs for the purpose of securing the lead wire cables, The newly developed ceramic attachment features a combination of hoops made of monolithic SiC or SiC/SiC CMC (which are joined to the test article) and high temperature ceramic cement. Two instrumented CMC panels were tested in a burner rig for a total of 40 cycles to 1150 C (2100 F). A cycle consisted of rapid heating to 1150 C (2100 F), a 5 minute hold at 1150 C (2100 F), and then cooling down to room temperature in 2 minutes. The thin film sensor systems provided repeatable temperature measurements for a maximum of 25 thermal cycles. Two of the monolithic SiC hoops debonded during the sensor fabrication process and two of the SiC/SiC CMC hoops failed during testing. The hoops filled with ceramic cement, however, showed no sign of detachment after 40 thermal cycle test. The primary failure mechanism of this sensor system was the loss of the fine lead wire-to-thin film connection, which either due to detachment of the fine lead wires from the thin film thermocouples or breakage of the fine wire.

  11. Reactive Attachment Disorder.

    ERIC Educational Resources Information Center

    Chapman, Sue

    2002-01-01

    Written by a British parent, this case study tells the story of an adopted child who experienced many difficulties adjusting to life at home and school. It describes attachment disorder, possible causes of attachment difficulties, the bonding cycle, therapeutic parenting, and how schools can support the re-nurturing process. (Contains references.)…

  12. Temperament and Attachment Disorders

    ERIC Educational Resources Information Center

    Zeanah, Charles H.; Fox, Nathan A.

    2004-01-01

    Reviewed in this article is research on children with reactive attachment disorder (RAD) who exhibit specific patterns of socially aberrant behavior resulting from being maltreated or having limited opportunities to form selective attachments. There are no data explaining why 2 different patterns of the disorder, an emotionally withdrawn-inhibited…

  13. Infant Feeding and Attachment.

    ERIC Educational Resources Information Center

    Ainsworth, Mary D. Salter; Tracy, Russel L.

    This paper has two major purposes: first, to consider how infant feeding behavior may fit into attachment theory; and second, to cite some evidence to show how an infant's early interaction with his mother in the feeding situation is related to subsequent development. It was found that sucking and rooting are precursor attachment behaviors that…

  14. Separation and Attachment

    ERIC Educational Resources Information Center

    Honig, Alice Sterling

    2005-01-01

    Developing secure attachments with babies gives them a very special gift--the foundation for good infant mental health! In this article, the author discusses how to develop secure attachments with babies. Babies who are in the care of others during the day often suffer from separations from their special adults. Thirteen "tips" to ensure that…

  15. Attachment Theory and Mindfulness

    ERIC Educational Resources Information Center

    Snyder, Rose; Shapiro, Shauna; Treleaven, David

    2012-01-01

    We initiate a dialog between two central areas in the field of psychology today: attachment theory/research and mindfulness studies. The impact of the early mother-infant relationship on child development has been well established in the literature, with attachment theorists having focused on the correlation between a mother's capacity for…

  16. Attachment Line Blockage Models

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Photographs shows the attachment-line experiment model with fairing and fence for supersonic attachment-line experiments. The fairing is intended to eliminate the wing/fuselage juncture shock and align the flow for the streamlined fence. The streamlined fence traps the turbulent fuselage boundary layer to prevent turbulent contamination of the leading edge flow.

  17. Attachment Theory and Mindfulness

    ERIC Educational Resources Information Center

    Snyder, Rose; Shapiro, Shauna; Treleaven, David

    2012-01-01

    We initiate a dialog between two central areas in the field of psychology today: attachment theory/research and mindfulness studies. The impact of the early mother-infant relationship on child development has been well established in the literature, with attachment theorists having focused on the correlation between a mother's capacity for…

  18. The star identification, pointing and tracking system of UVSTAR, an attached payload instrument system for the Shuttle Hitchhiker-M platform

    NASA Technical Reports Server (NTRS)

    Decarlo, Francesco; Stalio, Roberto; Trampus, Paolo; Broadfoot, A. Lyle; Sandel, Bill R.; Sicuranza, Giovanni

    1993-01-01

    We describe an algorithm for star identification and pointing/tracking of a spaceborne electro-optical system and simulation analyses to test the algorithm. The algorithm will be implemented in the guiding system of UVSTAR, a spectrographic telescope for observations of astronomical and planetary sources operating in the 500-1250 A waveband at approximately 1 A resolution. The experiment is an attached payload and will fly as a Hitchhiker-M payload on the Shuttle. UVSTAR includes capabilities for independent target acquisition and tracking. The spectrograph package has internal gimbals that allow angular movement of plus or minus 3 deg from the central position. Rotation about the azimuth axis (parallel to the Shuttle z axis) and elevation axis (parallel to the Shuttle x axis) will actively position the field of view to center the target of interest in the fields of the spectrographs. The algorithm is based on an on-board catalog of stars. To identify star fields, the algorithm compares the positions of stars recorded by the guiding imager to positions computed from the on-board catalog. When the field has been identified, its position within the guiding imager field of view can be used to compute the pointing corrections necessary to point to a target of interest. In tracking mode, the software uses the past history to predict the quasi-periodic attitude control motions of the shuttle and sends pointing commands to cancel the motion and stabilize UVSTAR on the target. The guiding imager (guider) will have an 80-mm focal length and f/1.4 optics giving a field of view of 6 deg x 4.5 deg using a 385 x 288 pixel intensified CCD. It will be capable of providing high accuracy (better than 2 arc-sec) attitude determination from coarse (6 deg x 4.5 deg) initial knowledge of the pointing direction; and of pointing toward the target. It will also be capable of tracking at the same high accuracy with a processing time of less than a few hundredths of a second.

  19. In vitro attachment of trypanosomes to plastic.

    PubMed

    Hommel, M; Robertson, E

    1976-04-15

    Description of an in vitro system for the study of the attachment of trypanosomes to polystyrene flasks by means of hemidesmosomes. This type of attachment, whose significance is so far unknown, reproduces a natural stage in the life cycle of medically important trypanosomatid flagellates in their vector.

  20. Internal Representational Models of Attachment Relationships.

    ERIC Educational Resources Information Center

    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…

  1. Loss and Disorganization from an Attachment Perspective

    ERIC Educational Resources Information Center

    Thomson, Paula

    2010-01-01

    In this article, it is hypothesized that disorganizing, disorienting, and unresolved states of mind about loss experiences, as classified by the Adult Attachment Interview (AAI) coding system, may offer insight into the bereaved mind and may guide clinical treatment approaches. This article discusses pre-loss attachment organizations and the…

  2. Loss and Disorganization from an Attachment Perspective

    ERIC Educational Resources Information Center

    Thomson, Paula

    2010-01-01

    In this article, it is hypothesized that disorganizing, disorienting, and unresolved states of mind about loss experiences, as classified by the Adult Attachment Interview (AAI) coding system, may offer insight into the bereaved mind and may guide clinical treatment approaches. This article discusses pre-loss attachment organizations and the…

  3. Modelling of biological Cr(VI) removal in draw-fill reactors using microorganisms in suspended and attached growth systems.

    PubMed

    Tekerlekopoulou, Athanasia G; Tsiflikiotou, Maria; Akritidou, Lydia; Viennas, Anastasios; Tsiamis, George; Pavlou, Stavros; Bourtzis, Kostas; Vayenas, Dimitris V

    2013-02-01

    The kinetics of hexavalent chromium bio-reduction in draw-fill suspended and attached growth reactors was examined using sugar as substrate and indigenous microorganisms from the industrial sludge of the Hellenic Aerospace Industry. Initially, experiments in suspended growth batch reactors for Cr (VI) concentrations of 1.4-110 mg/l were carried out, to extensively study the behaviour of a mixed culture. The maximum Cr(VI) reduction rate of 2 mg/l h was achieved for initial concentration 12.85 mg/l with biomass production rate 4.1 mg biomass/l h. Analysis of the microbial structure in the batch reactor culture indicated that the dominant bacterial communities were constituted by bacterial members of Raoultella sp., Citrobacter sp., Klebsiella sp., Salmonella sp., Achromobacter sp. and Kerstersia sp. while the dominant fungal strain was that of Pichia jadinii. Experiments using the same mixed culture were also carried out in packed-bed reactors with plastic support media. High removal rates were achieved (2.0 mg/l h) even in high initial concentrations (109 mg/l). A combination of the model of Tsao and Hanson for growth enhancement and that of Aiba and Shoda for growth inhibition was used in order to describe and predict the process of Cr(VI) bio-reduction in suspended growth and packed-bed reactors. Kinetic constants of the equation obtained from both batch (or draw-fill) culture experiments. In the draw-fill experiments at the packed-bed reactor, hexavalent chromium inhibitory effects were minimized increasing the inhibitory constant value K(i)' at 148.5 mg/l, compared to suspended growth experiments which was K(i) = 8.219 mg/l. The model adequately predicts hexavalent chromium reduction in both batch reactors for all initial concentrations tested.

  4. [Mentalization and attachment transmission].

    PubMed

    Böhmann, Johann; Fritsch, Sophia; Lück, Monika; Stumpe, Anna; Taubner, Svenja; Vesterling, Christina

    2014-01-01

    The present study was investigating the predictive role of maternal mentalizing and general as well as depressive symptom burden for attachment security at the end of the first year on a sample of 44 mother-child-dyads from a low-risk community study. Maternal mentalizing was assessed in a multidimensional way as Reflective Functioning (off-line) and Mind-Mindedness (on-line). The design was longitudinal measuring maternal Mind-Mindedness from a videotaped mother-child-play-interaction at the age of three months. General and depressive symptom burden was assessed using the SCL-90-R when the children were nine months old. Maternal attachment and Reflective-Functioning, using the Adult-Attachment-Interview, as well as children's attachment behavior, using the Strange-Situation-Test, were investigated at the age of twelve months. Secure maternal attachment was associated with higher Reflective Functioning, higher frequency of Mind-Mindedness and lower general and depressive symptom burden. A moderation-analysis showed a statistical trend (p = .08) that the interaction of the frequency of mind-related comments, general symptom severity and maternal attachment has a predictive value for infantile attachment security. Results can be tentatively interpreted that mothers with insecure attachment who had a lower general symptom burden and who related to their three-months old babies with a high frequency of mind-related-comments were more likely to have securely attached children. Thus, results may serve as a groundwork for projects aiming to prevent the transmission of insecure attachment by strengthening maternal Mind-Mindedness and working on the reduction of maternal general symptom burden.

  5. SPENT FUEL CASK IMPACT LIMITER ATTACHMENT DESIGN DEFICIENCIES

    SciTech Connect

    Leduc, D; Jeffery England, J

    2007-10-16

    A recent structural analysis of the T-3 Spent Fuel Containment Cask found problems with the design of the attachment system. Assumptions in the original SARP concerning the loading in the attachment bolts were found to be inaccurate in certain drop orientations. Similar weaknesses in the attachment system designs of other casks were also noted. This paper documents the lessons learned and their applicability to impact limiter attachment system designs.

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

    PubMed

    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.

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

    PubMed

    Scherz, Mark D; Daza, Juan D; Köhler, Jörn; Vences, Miguel; Glaw, Frank

    2017-01-01

    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 megalepissp. 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.

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

    PubMed Central

    Daza, Juan D.; Köhler, Jörn; Vences, Miguel; Glaw, Frank

    2017-01-01

    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. PMID:28194313

  9. Attachment style and interpersonal trauma in refugees.

    PubMed

    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.

  10. INSECURE ATTACHMENTS AND THEIR INTERMINGLING TRANSFERENCES.

    PubMed

    Silverman, Doris K

    2017-06-01

    There are least two different but interrelated motivational systems in human beings both of which begin in infancy: the attachment system and the separate, but interacting, psychodynamic system. Each of these systems is the basis of transference. A major focus of the paper is the affect-regulating feature of the attachment system. Infants' emotional states can be well-regulated or dysregulated as they emerge in interactions with their primary caregiver. Aberrant interactions of dysregulation typically lead to the development of insecure or disorganized attachments. Rudimentary transference fantasies initially emerge as the child makes sense or meaning about such maladaptive interactions. Our complex minds comprise multi-determined, personally organized fantasies which include those derived from both the attachment system and the psychodynamic one. I present a clinical description of how these two transference fantasies intersect in the mental life of a patient. A clinical case is offered whose focus is on enactments, transferences, and countertransference.

  11. Thinking about children's attachments.

    PubMed

    Rees, C A

    2005-10-01

    Disordered parental attachment can commit children to lives characterised by relationship difficulties, behaviour problems, educational failure, and poor self-esteem. It is a major root of trans-generational neglect and abuse and frequently underlies mental health problems, drug and alcohol addiction, homelessness, and crime. Early childhood setting of hypothalamus-pituitary-adrenal axis function appears to contribute to these costly difficulties. More broadly, the concept of attachment can contribute to defining and managing the psychosocial dimension of routine paediatric care. The current under-representation of attachment in paediatric education, practice, and research needs to be rectified.

  12. Photon Induced Electron Attachment.

    DTIC Science & Technology

    1984-12-01

    initial measure- ments was that high switch currents and long pulse durations appear to lead to substantially enhanced attachment rates in C3F8 ...similar conditions, but with 1.9 x 1015 C3F8 molecules/cm 3 added to the switch gas mixture. The initial current rise is comparable in both plots, but the...enhanced attachment during the switch opening time period. B. C0O Laser Excitation The photon enhanced attachment of the three gases NF3, C3F8 I and

  13. Sexual dimorphism in the attachment ability of the ladybird beetle Coccinella septempunctata on soft substrates

    NASA Astrophysics Data System (ADS)

    Heepe, Lars; Petersen, Dennis S.; Tölle, Lisa; Wolff, Jonas O.; Gorb, Stanislav N.

    2017-01-01

    Many insects possess adhesive foot pads, which enable reliable attachment to diverse and unpredictable substrates. The function of these adhesive organs was shown to be affected by environmental conditions such as substrate roughness, chemistry, and ambient humidity. So far, the attachment ability 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 stiffness on the attachment ability of insects, we have performed friction experiments with female and male ladybird beetles Coccinella septempunctata on smooth silicone elastomer substrates of different stiffness, using a centrifugal force tester. Whereas in females, the attachment ability was not affected by the substrate stiffness within the range of tested stiffness, males showed decreasing attachment ability with decreasing substrate stiffness. This sexual dimorphism in attachment ability is explained by the presence of a specialized, discoidal seta type in males, which is not present in females. It is argued that discoidal setae, when softer if compared to the substrate, may show an advantageous peak-free interfacial stress distribution when being pulled off the substrate. For such setae being stiffer if compared the substrate, they potentially show increased edge stress concentration. In this case, lower pull-off forces are expected, in agreement with the experimentally obtained results. With the present study, we demonstrate for the first time that the substrate stiffness may have an effect on the attachment ability of climbing animals, which may also be of relevance for technical and medical applications involving adhesion to soft substrates.

  14. Atypical Patterns of Early Attachment: Theory, Research, and Current Directions.

    ERIC Educational Resources Information Center

    Barnett, Douglas; Vondra, Joan I.

    1999-01-01

    Reviews conceptual background on atypical patterns of early attachments, including basic theoretical terms and constructs of attachment theory; the nature and function of the original classification system; notions of "exceptional cases" or "atypical patterns"; and implications of atypicality for both a classification system of attachment behavior…

  15. Longitudinal and lateral-directional static aerodynamic characteristics of an unpowered escape system extraction rocket model with attached launch tubes

    NASA Technical Reports Server (NTRS)

    Huffman, J. K.; Fox, C. H., Jr.; Satterthwaite, R. E.

    1977-01-01

    An escape system extraction rocket proposed for use on the Rotor Systems Research Aircraft was tested at Mach numbers of 0.1 and 0.3 through an angle of attack range from -2 deg to 102 deg and an angle of sideslip range from 0 deg to 15 deg in the Langley 7- by 10-foot high speed tunnel. The data are presented without analysis.

  16. Mirror Attachment For Borescope

    NASA Technical Reports Server (NTRS)

    Gearhart, John F.; Peloquin, James E.

    1994-01-01

    Attachment for articulated borescope provides views into small, normally inaccessible spaces. Simple small round mirror on extension arm welded to borescope head. Tilted at angle to axis of borescope head, mirror provides views sideways to borescope head. Disassembly of turbopump blades not necessary to enable fluorescent-penetrant-dye inspection. Attachment used to inspect difficult-to-reach internal parts of other assemblies. Also used for inspection with ordinary white light.

  17. Mirror Attachment For Borescope

    NASA Technical Reports Server (NTRS)

    Gearhart, John F.; Peloquin, James E.

    1994-01-01

    Attachment for articulated borescope provides views into small, normally inaccessible spaces. Simple small round mirror on extension arm welded to borescope head. Tilted at angle to axis of borescope head, mirror provides views sideways to borescope head. Disassembly of turbopump blades not necessary to enable fluorescent-penetrant-dye inspection. Attachment used to inspect difficult-to-reach internal parts of other assemblies. Also used for inspection with ordinary white light.

  18. Micromechanical die attachment surcharge

    DOEpatents

    Filter, William F.; Hohimer, John P.

    2002-01-01

    An attachment structure is disclosed for attaching a die to a supporting substrate without the use of adhesives or solder. The attachment structure, which can be formed by micromachining, functions purely mechanically in utilizing a plurality of shaped pillars (e.g. round, square or polygonal and solid, hollow or slotted) that are formed on one of the die or supporting substrate and which can be urged into contact with various types of mating structures including other pillars, a deformable layer or a plurality of receptacles that are formed on the other of the die or supporting substrate, thereby forming a friction bond that holds the die to the supporting substrate. The attachment structure can further include an alignment structure for precise positioning of the die and supporting substrate to facilitate mounting the die to the supporting substrate. The attachment structure has applications for mounting semiconductor die containing a microelectromechanical (MEM) device, a microsensor or an integrated circuit (IC), and can be used to form a multichip module. The attachment structure is particularly useful for mounting die containing released MEM devices since these devices are fragile and can otherwise be damaged or degraded by adhesive or solder mounting.

  19. Spray-irrigation system attached to high-speed drills for simultaneous prevention of local heating and preservation of a clear operative field in spinal surgery.

    PubMed

    Sasaki, Manabu; Morris, Shayne; Goto, Tetsu; Iwatsuki, Koichi; Yoshimine, Toshiki

    2010-01-01

    Heat generation due to drilling during spinal surgery is potentially hazardous to nerves. Saline irrigation is often performed to prevent such local heating, but sometimes floods and obscures the operative field. We have developed a spray-irrigation system for attachment to high-speed drills, which sprays saline solution with an air-jet in the direction of the surface cut by the drill. We anticipated that this air jet would create a clearer operative view by displacing excess fluid, and would also provide an added cooling effect greater than that of irrigation with saline. This study was designed to evaluate these predicted effects of the spray-irrigation system compared to conventional irrigation. A thermography study was performed to confirm the cooling effect of the spray-irrigation system. A plaster board coated with adhesives was drilled at 100,000 rpm along a 10-cm line for a duration of 20 seconds. Thermograms were recorded every minute, without cooling, with irrigation, and with the spray-irrigation system. To examine the operative views, continuous drilling for a period of seconds was performed with conventional irrigation and with the spray-irrigation system. Local heating was inhibited by the spray-irrigation system to 14-30% of that with irrigation. A clear operative field was maintained during continuous drilling using the spray-irrigation system through the air-jet action of the system. The spray-irrigation system can simultaneously provide effective cooling and a clear operative field during surgical manipulations with high-speed drills.

  20. Examining the meaning attached to mental illness and mental health services among justice system-involved youth and their parents.

    PubMed

    Watson, Amy C; Kelly, Brian L; Vidalon, Theresa M

    2009-08-01

    A large percentage of youth involved in the juvenile justice system experience mental health problems, yet many do not receive mental health care. In this study, we used a process-focused framework of mental health decision making to gain insight into the use of mental health services among these youth. In-depth interviews were conducted with nine youth and nine parents participating in a program servicing youth with mental health problems who have been in detention. Themes related to problem recognition, the decision to seek and participate in services, subjective norms, and juvenile justice system involvement emerged. Most families acknowledged their youth was having problems, but few defined those problems in mental health terms. This did not prevent them from seeking services, although some were not able to access adequate services until the justice system became involved. Participants were aware of negative attitudes about mental illness, and might have limited their social networks to shield themselves.

  1. Methanol production from eucalyptus wood chips. Attachment VIII. The wood-fueled gasification system, Evergreen Energy Corporation's final engineering report

    SciTech Connect

    Fishkind, H.H.

    1982-06-01

    Evergreen Energy Corporation provided projected cost and operating data on the Evergreen/Texaco entrained-bed wood gasification system currently under development as an alternative to the state-of-the-art fixed-bed wood gasification system proposed by Davy McKee. Overall capital costs for the total plant remain about the same at approx. $250 million. The Evergreen/Texaco system will provide significant capital cost savings in the gasifiers, gas cleanup, and waste water treatment sections, and eliminate the need for a large off-site wood-fired power boiler. These reductions are offset by higher investments in the feedstock preparation, drying, and feeding section plus the need for a larger air separation plant and compressor to supply oxygen at high pressure to the gasifier.

  2. Methanol production from eucalyptus wood chips. Attachment IV. Health and safety aspects of the eucalypt biomass to methanol energy system

    SciTech Connect

    Fishkind, H.H.

    1982-06-01

    The basic eucalyptus-to-methanol energy process is described and possible health and safety risks are identified at all steps of the process. The toxicology and treatment for exposure to these substances are described and mitigating measures are proposed. The health and safety impacts and risks of the wood gasification/methanol synthesis system are compared to those of the coal liquefaction and conversion system. The scope of this report includes the health and safety risks of workers (1) in the laboratory and greenhouse, where eucalyptus seedlings are developed, (2) at the biomass plantation, where these seedlings are planted and mature trees harvested, (3) transporting these logs and chips to the refinery, (4) in the hammermill, where the logs and chips will be reduced to small particles, (5) in the methanol synthesis plant, where the wood particles will be converted to methanol, and (6) transporting and dispensing the methanol. Finally, the health and safety risks of consumers using methanol is discussed.

  3. Adult attachment interviews of women from low-risk, poverty, and maltreatment risk samples: comparisons between the hostile/helpless and traditional AAI coding systems.

    PubMed

    Frigerio, Alessandra; Costantino, Elisabetta; Ceppi, Elisa; Barone, Lavinia

    2013-01-01

    The main aim of this study was to investigate the correlates of a Hostile-Helpless (HH) state of mind among 67 women belonging to a community sample and two different at-risk samples matched on socio-economic indicators, including 20 women from low-SES population (poverty sample) and 15 women at risk for maltreatment being monitored by the social services for the protection of juveniles (maltreatment risk sample). The Adult Attachment Interview (AAI) protocols were reliably coded blind to the samples' group status. The rates of HH classification increased in relation to the risk status of the three samples, ranging from 9% for the low-risk sample to 60% for the maltreatment risk sample to 75% for mothers in the maltreatment risk sample who actually maltreated their infants. In terms of the traditional AAI classification system, 88% of the interviews from the maltreating mothers were classified Unresolved/Cannot Classify (38%) or Preoccupied (50%). Partial overlapping between the 2 AAI coding systems was found, and discussion concerns the relevant contributions of each AAI coding system to understanding of the intergenerational transmission of maltreatment.

  4. Autism and Attachment: The Attachment Q-Sort

    ERIC Educational Resources Information Center

    Rutgers, Anna H.; Van Ijzendoorn, Marinus H.; Bakermans-Kranenburg, Marian J.; Swinkels, Sophie H. N.

    2007-01-01

    Children with autism are able to show secure attachment behaviours to their parents/caregivers. Most studies on attachment in children with autism used a (modified) Strange Situation Procedure (SSP) to examine attachment security. An advantage of the Attachment Q-Sort (AQS) over the SSP is that it can be attuned to the secure-base behaviour of…

  5. Three-dimensional distribution of polymorphs and magnesium in a calcified underwater attachment system by diffraction tomography

    PubMed Central

    Leemreize, Hanna; Almer, Jonathan D.; Stock, Stuart R.; Birkedal, Henrik

    2013-01-01

    Biological materials display complicated three-dimensional hierarchical structures. Determining these structures is essential in understanding the link between material design and properties. Herein, we show how diffraction tomography can be used to determine the relative placement of the calcium carbonate polymorphs calcite and aragonite in the highly mineralized holdfast system of the bivalve Anomia simplex. In addition to high fidelity and non-destructive mapping of polymorphs, we use detailed analysis of X-ray diffraction peak positions in reconstructed powder diffraction data to determine the local degree of Mg substitution in the calcite phase. These data show how diffraction tomography can provide detailed multi-length scale information on complex materials in general and of biomineralized tissues in particular. PMID:23804437

  6. Three-dimensional distribution of polymorphs and magnesium in a calcified underwater attachment system by diffraction tomography.

    PubMed

    Leemreize, Hanna; Almer, Jonathan D; Stock, Stuart R; Birkedal, Henrik

    2013-09-06

    Biological materials display complicated three-dimensional hierarchical structures. Determining these structures is essential in understanding the link between material design and properties. Herein, we show how diffraction tomography can be used to determine the relative placement of the calcium carbonate polymorphs calcite and aragonite in the highly mineralized holdfast system of the bivalve Anomia simplex. In addition to high fidelity and non-destructive mapping of polymorphs, we use detailed analysis of X-ray diffraction peak positions in reconstructed powder diffraction data to determine the local degree of Mg substitution in the calcite phase. These data show how diffraction tomography can provide detailed multi-length scale information on complex materials in general and of biomineralized tissues in particular.

  7. Attachment Theory in Supervision: A Critical Incident Experience

    ERIC Educational Resources Information Center

    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…

  8. Attachment Theory in Supervision: A Critical Incident Experience

    ERIC Educational Resources Information Center

    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…

  9. Attachment Organization and History of Suicidal Behavior in Clinical Adolescents.

    ERIC Educational Resources Information Center

    Adam, Kenneth S.; And Others

    1996-01-01

    Adolescents in psychiatric treatment (N=133) participated in a case-comparison study investigating the association of attachment patterns with a history of suicidal behaviors. Attachment patterns were assessed using the Adult Attachment Interview. In accordance with definitions provided in the scoring system, 86% of case and 78% of comparison…

  10. Reactive attachment disorder.

    PubMed

    Hornor, Gail

    2008-01-01

    Child abuse and neglect affects the lives of many American children and can result in physical injury and disability as well as psychological trauma. Reactive attachment disorder (RAD) is one possible psychological consequence of child abuse and neglect for very young children, younger than 5 years of age. RAD is described as markedly disturbed and developmentally inappropriate social relatedness usually beginning before age 5 years. These behavioral manifestations are the direct result of and come after pathogenic care. To better understand RAD, it is first necessary to understand attachment; therefore, attachment theory is examined. Risk factors for the development of RAD are presented. Implications for pediatric nurse practitioner practice are explored. The pediatric nurse practitioner can play a vital role in recognizing RAD and ensuring that children with this disorder receive prompt mental health assessment and therapy.

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

    PubMed

    Zahradnicek, Oldrich; Horacek, Ivan; Tucker, Abigail S

    2012-09-01

    This paper describes tooth development in a basal squamate, Paroedura picta. Due to its reproductive strategy, mode of development and position within the reptiles, this gecko represents an excellent model organism for the study of reptile development. Here we document the dental pattern and development of non-functional (null generation) and functional generations of teeth during embryonic development. Tooth development is followed from initiation to cytodifferentiation and ankylosis, as the tooth germs develop from bud, through cap to bell stages. The fate of the single generation of non-functional (null generation) teeth is shown to be variable, with some teeth being expelled from the oral cavity, while others are incorporated into the functional bone and teeth, or are absorbed. Fate appears to depend on the initiation site within the oral cavity, with the first null generation teeth forming before formation of the dental lamina. We show evidence for a stratum intermedium layer in the enamel epithelium of functional teeth and show that the bicuspid shape of the teeth is created by asymmetrical deposition of enamel, and not by folding of the inner dental epithelium as observed in mammals.

  12. Bio-inspired Gecko Micro-surface for Drag Reduction in Turbulent Flows

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

    Direct Numerical Simulations of a turbulent channel flow with a porous wall inspired from the Gecko lizard were performed at Reynolds number of Reτ = 450 . Two superposed fluids were considered. As initial condition, one fluid fills the microfibrillar surface, the interface with the overlying fluid being flat and corresponding to the crests plane. The code is based on a finite difference scheme with a Runge Kutta and fractional step. The porous wall is modeled with the immersed boundary method, while the dynamic of the interface between the two fluids is solved with a level set method. A parametric study has been performed varying the viscosity ratio between the two fluids. Two cases have been considered, with and without surface tension. Without surface tension the microfibrillar wall acts as a rough wall increasing the drag. However, when the surface tension is large enough to maintain the interface stable, the external fluid cannot enter into the porous wall and an effective slip is produced. When the fluid in the porous wall has a viscosity 100 times smaller than that of the overlying fluid, a drag reduction of about 60 % can be observed. In this case, the near wall coherent structures become significantly weaker. The numerical simulations were performed on XSEDE TACC under Grant No. CTS070066. S.L., I.A. and K.C. were supported by ONR MURI grant.

  13. Ultrastructural description of spermiogenesis within the Mediterranean Gecko, Hemidactylus turcicus (Squamata: Gekkonidae).

    PubMed

    Rheubert, Justin L; Siegel, Dustin S; Venable, Katherine J; Sever, David M; Gribbins, Kevin M

    2011-10-01

    We studied spermiogenesis in the Mediterranean Gecko, Hemidactylus turcicus, at the electron microscope level and compared to what is known within other Lepidosaurs. In H. turcicus germ cells are connected via cytoplasmic bridges where organelle and cytoplasm sharing is observed. The acrosome develops from merging transport vesicles that arise from the Golgi and subsequently partition into an acrosomal cap containing an acrosomal cortex, acrosomal medulla, perforatorium, and subacrosomal cone. Condensation of DNA occurs in a spiral fashion and elongation is aided by microtubules of the manchette. A nuclear rostrum extends into the subacrosomal cone and is capped by an epinuclear lucent zone. Mitochondria and rough endoplasmic reticulum migrate to the posterior portion of the developing germ cell during the cytoplasmic shift and the flagellum elongates. Mitochondria surround the midpiece as the anlage of the annulus forms. The fibrous sheath begins at mitochondrial tier 3 and continues into the principal piece. Peripheral fibers associated with microtubule doublets 3 and 8 are grossly enlarged. During the final stages of germ cell development spermatids are wrapped with a series of Sertoli cell processes, which exhibit ectoplasmic specializations and differing cytoplasmic consistencies. The results observed here corroborate previous studies, which show the conservative nature of sperm morphology. However, ultrastructural character combinations specific to sperm and spermiogenesis seem to differ among taxa. Further studies into sperm morphology are needed in order to judge the relevance of the ontogenic changes recorded here and to determine their role in future studies on amniote evolution.

  14. Cyrtodactylus dati, a new forest dwelling Bent-toed Gecko (Squamata: Gekkonidae) from southern Vietnam.

    PubMed

    Van Tri, Ngo

    2013-02-19

    A new species of Bent-toed Gecko, Cyrtodactylus dati sp. nov. is described from the secondary evergreen forests of Bu Dop District, Binh Phuoc Province, Vietnam. It differs from all other species of Indochinese and Thai-Malay Cyrtodactylus by having a maximum SVL of 70.1 mm (n=6); no distinct dark blotches on the head in adults; no continuous nuchal loop; a blotched dorsal pattern; 17-19 interorbital scales across the frontal bone; 23-26 scales in a straight line between eye and nostril; 42-48 rows of ventral scales between ventrolateral folds; 20-22 irregular, longitudinal rows of keeled tubercles at midbody between the ventrolateral folds; a series of five or six precloacal pores medially interrupted by one poreless scale in males; three or four femoral pores on each thigh in males; 4-7 enlarged scales beneath thighs; 12-13 subdigital lamellae on first toe; 18-19 subdigital lamellae on fourth toe; and small subcaudal scales.

  15. Phylogeny and cryptic diversity in geckos (Phyllopezus; Phyllodactylidae; Gekkota) from South America's open biomes.

    PubMed

    Gamble, Tony; Colli, Guarino R; Rodrigues, Miguel T; Werneck, Fernanda P; Simons, Andrew M

    2012-03-01

    The gecko genus Phyllopezus occurs across South America's open biomes: Cerrado, Seasonally Dry Tropical Forests (SDTF, including Caatinga), and Chaco. We generated a multi-gene dataset and estimated phylogenetic relationships among described Phyllopezus taxa and related species. We included exemplars from both described Phyllopezus pollicaris subspecies, P. p. pollicaris and P. p.przewalskii. Phylogenies from the concatenated data as well as species trees constructed from individual gene trees were largely congruent. All phylogeny reconstruction methods showed Bogertia lutzae as the sister species of Phyllopezus maranjonensis, rendering Phyllopezus paraphyletic. We synonymized the monotypic genus Bogertia with Phyllopezus to maintain a taxonomy that is isomorphic with phylogenetic history. We recovered multiple, deeply divergent, cryptic lineages within P. pollicaris. These cryptic lineages possessed mtDNA distances equivalent to distances among other gekkotan sister taxa. Described P. pollicaris subspecies are not reciprocally monophyletic and current subspecific taxonomy does not accurately reflect evolutionary relationships among cryptic lineages. We highlight the conservation significance of these results in light of the ongoing habitat loss in South America's open biomes. Copyright © 2011 Elsevier Inc. All rights reserved.

  16. Multilocus phylogeography reveals nested endemism in a gecko across the monsoonal tropics of Australia.

    PubMed

    Moritz, C; Fujita, M K; Rosauer, D; Agudo, R; Bourke, G; Doughty, P; Palmer, R; Pepper, M; Potter, S; Pratt, R; Scott, M; Tonione, M; Donnellan, S

    2016-03-01

    Multilocus phylogeography can uncover taxonomically unrecognized lineage diversity across complex biomes. The Australian monsoonal tropics include vast, ecologically intact savanna-woodland plains interspersed with ancient sandstone uplands. Although recognized in general for its high species richness and endemism, the biodiversity of the region remains underexplored due to its remoteness. This is despite a high rate of ongoing species discovery, especially in wetter regions and for rock-restricted taxa. To provide a baseline for ongoing comparative analyses, we tested for phylogeographic structure in an ecologically generalized and widespread taxon, the gecko Heteronotia binoei. We apply coalescent analyses to multilocus sequence data (mitochondrial DNA and eight nuclear DNA introns) from individuals sampled extensively and at fine scale across the region. The results demonstrate surprisingly deep and geographically nested lineage diversity. Several intra-specific clades previously shown to be endemic to the region were themselves found to contain multiple, short-range lineages. To infer landscapes with concentrations of unique phylogeographic diversity, we probabilistically estimate the ranges of lineages from point data and then, combining these estimates with the nDNA species tree, estimate phyloendemism across the region. Highest levels of phyloendemism occur in northern Top End, especially on islands, across the topographically complex Arnhem escarpment, and across the sandstone ranges of the western Gulf region. These results drive home that deep phylogeographic structure is prevalent in tropical low-dispersal taxa, even ones that are ubiquitous across geography and habitats. © 2015 John Wiley & Sons Ltd.

  17. NOTE: Fabrication of a gecko-like hierarchical fibril array using a bonded porous alumina template

    NASA Astrophysics Data System (ADS)

    Suryadi Kustandi, Tanu; Samper, Victor Donald; Ng, Wan Sing; Chong, Ai Shing; Gao, Han

    2007-10-01

    We report a new method to fabricate a hierarchical microfibril array by using bonded porous alumina templates. The fabrication approach extends a powerful and well-established technique of creating porous alumina to create a polymer multilevel structure, mimicking the hierarchical structure of gecko adhesive foot hairs. The nanoporous alumina (pore diameter ≈60 nm; interpore distance ≈100 nm) was generated by the anodization of an aluminum film in an oxalic acid solution. The microporous alumina was produced by exploiting the parallel wafer-scale processing of conventional lithography and anisotropic chemical etching of the thick film of anodic alumina pores. The micro- and nanoporous alumina membranes were subsequently brought into intimate contact and their bonding was accomplished by means of capillary forces and then van der Waals bonding. Hierarchical polymeric microfibrils (fibril diameter ≈10 µm fibril length ≈70 µm) with nanofibril arrays at their tips were obtained after depositing a desired material into the pores and selective etching of the template membranes. The nanofibril has a lateral dimension of approximately 60 nm with length-to-diameter aspect ratios as high as 100:1.

  18. Elevated testosterone is required for male copulatory behavior and aggression in Madagascar ground gecko (Paroedura picta).

    PubMed

    Golinski, Alison; Kubička, Lukáš; John-Alder, Henry; Kratochvíl, Lukáš

    2014-09-01

    Elevated levels of gonadal androgens are often required for the expression of male-specific behavioral and morphological traits in all classes of vertebrates, including reptiles. Here, we tested the role of male gonadal androgens in the control of male sexual behavior, aggressive behavior, and size of the hemipenes in the gecko Paroedura picta. We performed hormonal manipulations involving castration with and without testosterone (T) replacement in males and application of exogenous T and ovariectomy in females. Castration suppressed sexual behavior and hemipenes size in males, and these effects were fully rescued by exogenous T. Sexual behavior and growth of the hemipenes were masculinized by male-typical levels of T in females, while ovariectomized females retained female-typical expression of these traits. These results indicate that the development of male sexual behavior in adult females does not require early or pubertal organization. Elevated T increased the likelihood of aggressive behavior directed toward a male intruder, but aggression occurred only rarely. Elevated T is necessary and sufficient for enlargement of the hemipenes and the expression of male sexual behavior in both males and females of Paroedura picta. In contrast to sexual behavior, the expression of aggressive behavior is apparently more dependent on other factors in addition to T itself.

  19. A new species of dwarf gecko in the genus Lygodactylus (squamata: Gekkonidae) from central Kenya.

    PubMed

    Malonza, Patrick K; Granthon, Carolina; Williams, Dean A

    2016-01-08

    A new species of Lygodactylus gecko (L. wojnowskii sp. nov.) is described from the vicinity of Chogoria Town on the eastern lower slopes of Mt. Kenya in central Kenya. A phylogeny based on mitochondrial and nuclear DNA shows that the proposed new taxon is distinct within the Lygodactylus picturatus group and is the sister lineage to L. mombasicus and L. kimhowelli. It is morphologically very similar to both L. mombasicus and L. keniensis but its dorsal coloration and pattern is different. Its dorsum is grey with dark stripes while its head has black and white stripes that form a Y-shaped mark. While the male throat pattern is similar to that of L. mombasicus, that of the female is like that of females and some males of Lygodactylus keniensis. Lygodactylus wojnowskii sp. nov. has a higher number of post-postmental scales (6) than do its close relatives (5). The new species is distributed on the lower slopes of mid-altitude areas on eastern Mt. Kenya, but it may occur in other areas at similar elevations in central Kenya. It is associated with short, scattered trees within agricultural areas. It has not yet been recorded within the protected Chogoria forest block of Mt. Kenya forest. It is likely present in Mwea National Reserve as it occurs in nearby areas.

  20. Ovarian control of growth and sexual size dimorphism in a male-larger gecko.

    PubMed

    Kubička, Lukáš; Schořálková, Tereza; Červenka, Jan; Kratochvíl, Lukáš

    2017-03-01

    Sexual size dimorphism (SSD) reflects sex-specific solutions to the allocation of energy among growth, reproduction and survival; however, the proximate mechanisms behind these solutions are still poorly known even in vertebrates. In squamates, sexual differences in body size used to be attributed to direct energy allocation to energetically demanding processes, largely to reproduction. In addition, SSD is assumed to be controlled by specific endogenous mechanisms regulating growth in a sex-specific manner, namely masculinization by male gonadal androgens or feminization by ovarian hormones. We performed a manipulative growth experiment in females of the male-larger gecko Paroedura picta in order to test the reproductive cost hypothesis, the male androgen hypothesis and the ovarian hormone hypothesis. Specifically, we investigated the effect of total ovariectomy, prepubertal ovariectomy, unilateral ovariectomy, and total ovariectomy followed by exogenous estradiol, dihydrotestosterone or testosterone treatment, on female growth in comparison to males and reproductively active females. The present results and the results of our previous experiments do not support the hypotheses that SSD reflects direct energy allocation to reproduction and that male gonadal androgens are involved. However, all lines of evidence, particularly the comparable growth of reproducing intact and unilaterally ovariectomized females, were concordant with the control of SSD by ovarian hormones. We suggest that feminization of growth by female gonadal hormones should be taken into consideration as an endogenous pathway responsible for the ontogeny of SSD in squamates. © 2017. Published by The Company of Biologists Ltd.