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Sample records for spider optimization probing

  1. Optically probing torsional superelasticity in spider silks

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P. [Department of Physical Sciences, IISER Mohali, Sector 81, Manauli, Mohali 140306 (India)

    2013-11-11

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10{sup 2−3} rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices.

  2. Optically probing torsional superelasticity in spider silks

    Kumar, Bhupesh; Thakur, Ashish; Panda, Biswajit; Singh, Kamal P.

    2013-01-01

    We investigate torsion mechanics of various spider silks using a sensitive optical technique. We find that spider silks are torsionally superelastic in that they can reversibly withstand great torsion strains of over 10 2−3 rotations per cm before failure. Among various silks from a spider, we find the failure twist-strain is greatest in the sticky capture silk followed by dragline and egg-case silk. Our in situ laser-diffraction measurements reveal that torsional strains on the silks induce a nano-scale transverse compression in its diameter that is linear and reversible. These unique torsional properties of the silks could find applications in silk-based materials and devices

  3. SPIDER: Probing the dawn of time from above the clouds

    Moncelsi, Lorenzo; Spider Collaboration

    2017-11-01

    SPIDER is a balloon-borne microwave polarimeter designed to measure cosmological B-modes on degree angular scales in the presence of Galactic foregrounds. With six independent telescopes housing a total of 2000 detectors in the 90 GHz and 150 GHz frequency bands, SPIDER is the most instantaneously-sensitive CMB polarimeter deployed on the sky to date. SPIDER was successfully launched from McMurdo Station, Antarctica in January 2015 and acquired science data for 16 days. We cover the in-flight performance and present highlights from the ongoing data-analysis. After a successful recovery, the SPIDER team is planning the next flight, featuring one foreground-optimized channel at 280GHz, which will allow us constrain the primordial tensor-mode amplitude at the level of r < 0.03 (99% CL), in the presence of foregrounds.

  4. SPIDER: Probing the Early Universe with a Suborbital Polarimeter

    Fraisse, Aurélien A.; SPIDER Collaboration

    2012-01-01

    SPIDER is a balloon-borne polarimeter designed to detect a divergence-free polarization pattern ("B-modes") in the Cosmic Microwave Background (CMB). In the inflationary scenario, the spectrum of the tensor perturbations that generate this signal is proportional to that of the primordial scalar perturbations through the tensor-to-scalar ratio r. The expected level of systematic error in the SPIDER instrument is significantly below the amplitude of an interesting cosmological B-mode signal with r=0.03. An optimized scanning strategy enables us to minimize uncertainty in the reconstruction of the Stokes parameters used to characterize the CMB, while providing access to a relatively wide range of angular scales. In the SPIDER field, the polarized emission from interstellar dust is as bright or brighter than the cosmological r=0.03 B-mode signal at all SPIDER frequencies (90, 150, and 280 GHz), a situation similar to that found in the "Southern Hole." Despite this foreground contamination, two 20-day flights of the SPIDER instrument will constrain the amplitude of the B-mode signal to rAPRA-NNX07AL64G), the National Science Foundation (ANT-1043515), the Gordon and Betty Moore Foundation, and the David and Lucile Packard Foundation. Support in Canada is provided by NSERC, the Canadian Space Agency, the Canada Foundation for Innovation, and CIFAR.

  5. Spider: Probing the Early Universe with a Large-Scale CMB Polarization Survey

    Jones, William

    The standard dark-matter and dark-energy dominated cosmological model (LCDM) has proven to be remarkably successful in describing the current state and past evolution of the Universe. However, there remain significant uncertainties regarding the physical mechanisms that established the initial conditions upon which the LCDM predictions rely. Theories of cosmic genesis - the extremely high energy mechanisms that established these conditions - should be expected to provide a natural description of the nearly flat geometry of the Universe, the existence of super-horizon density correlations, and the adiabatic, Gaussian and nearly scale-invariant nature of the observed primordial density perturbations. The primary objective of Spider is to subject models of the early Universe to observational test, probing fundamental physics at energy scales far beyond the reach of terrestrial particle accelerators. The main scientific result will be to characterize, or place stringent upper limits on the level of the odd-parity polarization of the CMB. In the context of the inflationary paradigm, Spider will confirm or exclude the predictions of the simplest single-field inflationary models near the Lyth bound, characterized by tensor to scalar ratios r 0.03. While viable alternatives to the inflationary paradigm are an active and important area of investigation, including string cosmologies and cyclic models, early Universe models described by inflationary periods are now widely accepted as the underlying cause behind much of what we observe in cosmology today. Nevertheless, we know very little about the mechanism that would drive inflation or the energy scale at which it occurred, and the paradigm faces significant questions about the viability of the framework as a scientific theory. Fortunately, inflationary paradigms and alternative theories offer distinct predictions regarding the statistical properties of the Cosmic Microwave Background radiation. Spider will use measurements

  6. Small Molecules from Spiders Used as Chemical Probes

    Olsen, Christian Adam; Kristensen, Anders S.; Strømgaard, Kristian

    2011-01-01

    Spiders are important species in ecological systems and as major predators of insects they are endowed with a plethora of low‐molecular‐weight natural products having intriguing biological activities. The isolation and biological characterization of these entities are well established, however......, only very recently have these compounds been used as templates for the design, synthesis, and biological evaluation of synthetic analogues. In contrast, the investigation of compounds responsible for chemical communication between spiders is far less developed, but recently new light has been shed onto...... the area of pheromones and allomones from spiders. Herein, we recapitulate these recent results, put them into perspective with previous findings, and provide an outlook for future studies of these chemotypes....

  7. Startle and spider phobia : Unilateral probes and the prediction of treatment effects

    de Jong, Peter J.; Visser, Sylvia; Merckelbach, Harald

    1996-01-01

    The present study explored two issues: (1) the predictive value of startle responses for treatment success and (2) the lateralization of affect-modulated startle responses. Approximately 40 days before behavioral treatment, monaural startle probes were presented to 20 women who were spider phobic

  8. An insect-feeding guild of carnivorous plants and spiders: does optimal foraging lead to competition or facilitation?

    Crowley, Philip H; Hopper, Kevin R; Krupa, James J

    2013-12-01

    Carnivorous plants and spiders, along with their prey, are main players in an insect-feeding guild found on acidic, poorly drained soils in disturbed habitat. Darwin's notion that these plants must actively attract the insects they capture raises the possibility that spiders could benefit from proximity to prey hotspots created by the plants. Alternatively, carnivorous plants and spiders may deplete prey locally or (through insect redistribution) more widely, reducing each other's gain rates from predation. Here, we formulate and analyze a model of this guild, parameterized for carnivorous sundews and lycosid spiders, under assumptions of random movement by insects and optimal foraging by predators. Optimal foraging here involves gain maximization via trap investment (optimal web sizes and sundew trichome densities) and an ideal free distribution of spiders between areas with and without sundews. We find no facilitation: spiders and sundews engage in intense exploitation competition. Insect attraction by plants modestly increases sundew gain rates but slightly decreases spider gain rates. In the absence of population size structure, optimal spider redistribution between areas with and without sundews yields web sizes that are identical for all spiders, regardless of proximity to sundews. Web-building spiders have higher gain rates than wandering spiders in this system at high insect densities, but wandering spiders have the advantage at low insect densities. Results are complex, indicating that predictions to be tested empirically must be based on careful quantitative assessment.

  9. Standardization and optimization of arthropod inventories-the case of Iberian spiders

    Bondoso Cardoso, Pedro Miguel

    2009-01-01

    and optimization of sampling protocols, especially for mega-diverse arthropod taxa. This study had two objectives: (1) propose guidelines and statistical methods to improve the standardization and optimization of arthropod inventories, and (2) to propose a standardized and optimized protocol for Iberian spiders......, by finding common results between the optimal options for the different sites. The steps listed were successfully followed in the determination of a sampling protocol for Iberian spiders. A protocol with three sub-protocols of varying degrees of effort (24, 96 and 320 h of sampling) is proposed. I also...

  10. Can ant-eating Zodarion spiders (Araneae: Zodariidae) develop on a diet optimal for euryphagous arthropod predators?

    Pekar, Stano; Toft, Søren

    2009-01-01

    . Such adaptations may then entail trade-offs in handling and utilization of alternative prey. To investigate behavioural as well as nutritional adaptations and the occurrence of the corresponding trade-offs in two ant-eating spiders of the genus Zodarion [Zodarion atlanticum Pekár & Cardoso and Zodarion germanicum...... (C. L. Koch)], spiders are reared on two diets: ants (i.e. their preferred prey) and fruit flies (i.e. an alternative prey that is nutritionally optimal for euryphagous spiders). Food consumption is observed and several fitness-related life-history parameters are measured. Although spiders readily...... accept ants, more than one-third of 35 spiders refuse to consume fruit flies and starve. Furthermore, severe hunger does not induce these individuals to accept fruit flies. Starving spiders die before moulting to the second stadium. Spiders that eat fruit flies increase only little and slowly in weight...

  11. SPIDER OPTIMIZATION. II. OPTICAL, MAGNETIC, AND FOREGROUND EFFECTS

    O'Dea, D. T.; Clark, C. N.; Contaldi, C. R.; Ade, P. A. R.; Amiri, M.; Burger, B.; Davis, G.; Benton, S. J.; Bock, J. J.; Crill, B. P.; Dore, O.; Filippini, J. P.; Bond, J. R.; Farhang, M.; Bonetti, J. A.; Bryan, S.; Chiang, H. C.; Fraisse, A. A.; Fissel, L. M.; Gandilo, N. N.

    2011-01-01

    SPIDER is a balloon-borne instrument designed to map the polarization of the cosmic microwave background (CMB) with degree-scale resolution over a large fraction of the sky. SPIDER's main goal is to measure the amplitude of primordial gravitational waves through their imprint on the polarization of the CMB if the tensor-to-scalar ratio, r, is greater than 0.03. To achieve this goal, instrumental systematic errors must be controlled with unprecedented accuracy. Here, we build on previous work to use simulations of SPIDER observations to examine the impact of several systematic effects that have been characterized through testing and modeling of various instrument components. In particular, we investigate the impact of the non-ideal spectral response of the half-wave plates, coupling between focal-plane components and Earth's magnetic field, and beam mismatches and asymmetries. We also present a model of diffuse polarized foreground emission based on a three-dimensional model of the Galactic magnetic field and dust, and study the interaction of this foreground emission with our observation strategy and instrumental effects. We find that the expected level of foreground and systematic contamination is sufficiently low for SPIDER to achieve its science goals.

  12. Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

    Brombin, M.; Spolaore, M.; Serianni, G.; Pomaro, N.; Taliercio, C.; Palma, M. Dalla; Pasqualotto, R.; Schiesko, L.

    2014-11-01

    A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors' holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns.

  13. Langmuir probes for SPIDER (source for the production of ions of deuterium extracted from radio frequency plasma) experiment: Tests in BATMAN (Bavarian test machine for negative ions)

    Brombin, M.; Spolaore, M.; Serianni, G.; Pomaro, N.; Taliercio, C.; Palma, M. Dalla; Pasqualotto, R.; Schiesko, L.

    2014-01-01

    A prototype system of the Langmuir probes for SPIDER (Source for the production of Ions of Deuterium Extracted from RF plasma) was manufactured and experimentally qualified. The diagnostic was operated in RF (Radio Frequency) plasmas with cesium evaporation on the BATMAN (BAvarian Test MAchine for Negative ions) test facility, which can provide plasma conditions as expected in the SPIDER source. A RF passive compensation circuit was realised to operate the Langmuir probes in RF plasmas. The sensors’ holder, designed to better simulate the bias plate conditions in SPIDER, was exposed to a severe experimental campaign in BATMAN with cesium evaporation. No detrimental effect on the diagnostic due to cesium evaporation was found during the exposure to the BATMAN plasma and in particular the insulation of the electrodes was preserved. The paper presents the system prototype, the RF compensation circuit, the acquisition system (as foreseen in SPIDER), and the results obtained during the experimental campaigns

  14. Attentional bias to moving spiders in spider fearful individuals.

    Vrijsen, Janna N; Fleurkens, Pascal; Nieuwboer, Wieteke; Rinck, Mike

    2009-05-01

    We investigated if an attentional bias for spiders in spider fearful individuals (SFs) can also be found for moving spiders, rather than static images. In Study 1, 28 SFs and 33 non-anxious controls (NACs) participated in a modified version of the dot probe paradigm: they had to react to a probe that appeared either in the next, previous, or side position of a spider's or a wheel's path. 24 SFs and 29 NACs participated in Study 2, in which a fourth, highly predictable, probe position was added. We expected that moving spiders would capture the attention of SFs. In addition, we tested whether SFs try to predict the movement of the spider to make it less threatening. As expected, SFs showed an attentional bias towards moving spiders. However, both groups reacted fastest to unpredictable movements, indicating that SFs and NACs alike anticipate unpredictable spider movements.

  15. Purification of a neurotoxin from the venom of the 'armed spider' and synthesis of a radioactive probe

    Santos, Raquel Gouvea; Renterghem, Catherine Van; Mori, Yasuo; Martin-Moutot, Nicole; Mansuelle, Pascal; Sampieri, Francois; Seagar, Michel; Lima, Maria Elena de

    2002-01-01

    The venom of the 'armed spider', a South American spider from the genus Phoneutria contains several toxins that exert important biological effects. ω-Phonetoxin IIA (ω-PtxIIA) is a potent neurotoxin from this venom evoking flaccid paralysis and death after intracerebro-ventricular injection in mouse. This toxin blocks HVA calcium channels. Calcium channels have been shown to be important targets in neurological pathophysiology like ataxia and migraine. In order to shed more light on the mechanism of action of w-PtxIIA, we have purified this toxin to synthesize a radioactive probe. Crude venom was fractionated in three steps of reversed-phase liquid chromatography (RP-HPLC). Spectrometric analysis of the purified fraction (causing flaccid paralysis) was recorded on a MALDI-TOF Perseptive Voyager Elite spectrometer and a 8363 kDa peptide was detected. After amino acid sequencing the purity of the peptide was confirmed and it was identified as ω-PtxIIA. ω-PtxIIA was radiolabeled with 125 I using the lactoperoxidase as a oxidizing agent. The stability of the probe synthesized was verified by the binding studies on rat brain synaptosomal membranes. The specific and saturable binding of the 125 I-ω-PtxIIA to the membranes indicate that the iodine introduced in the toxin molecule did not interfere with its activity. Native ω-PtxIIA competed with the 125 I-ω-PtxIIA bound to the specific sites on synaptosomes (IC 50 = 0.54 n M). In this paper we described a new and simpler purification protocol of the ω-PtxIIA and synthesized a probe that proved to be useful to study the mechanism of action of 125 I-ω-PtxIIA. Selective toxins for calcium channel are very useful tools to the study of some neuronal pathophysiology. (author)

  16. SPIDER SILK

    PORAV Viorica

    2014-05-01

    Full Text Available The strengthness and toughness of spider fiber and its multifunctional nature is only surpassed in some cases by synthetic high performance fibers. In the world of natural fibers, spider silk has been long time recognized as a wonder fiber for its unique combination of high strength and rupture elongation. Scientists in civil military engineering reveal that the power of biological material (spider silk lies in the geometric configuration of structural protein, and the small cluster of week hydrogen bonds that works together to resist force and dissipate energy. Each spider and each type of silk has a set of mechanical properties optimized for their biological function. Most silks, in particular deagline silk, have exceptional mechanical properties. They exhibit a unique combination of high tensile strength and extensibility (ductility. This enables a silk fiber to absorb a lot of energy before breaking (toughness, the area under a stress- strain curve. A frequent mistake made in the mainstream media is to confuse strength and toughness when comparing silk to other materials. As shown below in detail, weight for weight, silk is stronger than steel, but not as strong as Kevlar. Silk is,however, tougher than both.This paper inform about overview on the today trend in the world of spider silk.

  17. Tarantula spider

    ... page: //medlineplus.gov/ency/article/002855.htm Tarantula spider bite To use the sharing features on this ... This article describes the effects of a tarantula spider bite. The class of insects to which the ...

  18. Purification of a neurotoxin from the venom of the 'armed spider' and synthesis of a radioactive probe

    Santos, Raquel Gouvea [INSERM, Marseille (France). Lab. Canaux Ioniques]|[Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil); Renterghem, Catherine Van; Mori, Yasuo; Martin-Moutot, Nicole; Mansuelle, Pascal; Sampieri, Francois; Seagar, Michel [INSERM, Marseille (France). Lab. Canaux Ioniques; Cordeiro, Marta Nascimento; Diniz, Carlos Ribeiro [FUNED - Fundacao Ezequiel Dias, Belo Horizonte, MG (Brazil); Lima, Maria Elena de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Inst. de Ciencias Biologicas. Lab. de Venenos e Toxinas Animais

    2002-07-01

    The venom of the 'armed spider', a South American spider from the genus Phoneutria contains several toxins that exert important biological effects. {omega}-Phonetoxin IIA ({omega}-PtxIIA) is a potent neurotoxin from this venom evoking flaccid paralysis and death after intracerebro-ventricular injection in mouse. This toxin blocks HVA calcium channels. Calcium channels have been shown to be important targets in neurological pathophysiology like ataxia and migraine. In order to shed more light on the mechanism of action of w-PtxIIA, we have purified this toxin to synthesize a radioactive probe. Crude venom was fractionated in three steps of reversed-phase liquid chromatography (RP-HPLC). Spectrometric analysis of the purified fraction (causing flaccid paralysis) was recorded on a MALDI-TOF Perseptive Voyager Elite spectrometer and a 8363 kDa peptide was detected. After amino acid sequencing the purity of the peptide was confirmed and it was identified as {omega}-PtxIIA. {omega}-PtxIIA was radiolabeled with {sup 125} I using the lactoperoxidase as a oxidizing agent. The stability of the probe synthesized was verified by the binding studies on rat brain synaptosomal membranes. The specific and saturable binding of the {sup 125} I-{omega}-PtxIIA to the membranes indicate that the iodine introduced in the toxin molecule did not interfere with its activity. Native {omega}-PtxIIA competed with the {sup 125} I-{omega}-PtxIIA bound to the specific sites on synaptosomes (IC{sub 50}= 0.54 n M). In this paper we described a new and simpler purification protocol of the {omega}-PtxIIA and synthesized a probe that proved to be useful to study the mechanism of action of {sup 125} I-{omega}-PtxIIA. Selective toxins for calcium channel are very useful tools to the study of some neuronal pathophysiology. (author)

  19. Optimized Chemical Probes for REV-ERBα

    Trump, Ryan P.; Bresciani, Stefano; Cooper, Anthony W. J.; Tellam, James P.; Wojno, Justyna; Blaikley, John; Orband-Miller, Lisa A.; Kashatus, Jennifer A.; Dawson, Helen C.; Loudon, Andrew; Ray, David; Grant, Daniel; Farrow, Stuart N.; Willson, Timothy M.; Tomkinson, Nicholas C. O.

    2013-01-01

    REV-ERBα has emerged as an important target for regulation of circadian rhythm and its associated physiology. Herein, we report on the optimization of a series of REV-ERBα agonists based on GSK4112 (1) for potency, selectivity, and bioavailability. Potent REV-ERBα agonists 4, 10, 16, and 23 are detailed for their ability to suppress BMAL and IL-6 expression from human cells while also demonstrating excellent selectivity over LXRα. Amine 4 demonstrated in vivo bioavailability after either IV o...

  20. Eddy current testing probe optimization using a parallel genetic algorithm

    Dolapchiev Ivaylo

    2008-01-01

    Full Text Available This paper uses the developed parallel version of Michalewicz's Genocop III Genetic Algorithm (GA searching technique to optimize the coil geometry of an eddy current non-destructive testing probe (ECTP. The electromagnetic field is computed using FEMM 2D finite element code. The aim of this optimization was to determine coil dimensions and positions that improve ECTP sensitivity to physical properties of the tested devices.

  1. Standardless quantification by parameter optimization in electron probe microanalysis

    Limandri, Silvina P.; Bonetto, Rita D.; Josa, Víctor Galván; Carreras, Alejo C.; Trincavelli, Jorge C.

    2012-01-01

    A method for standardless quantification by parameter optimization in electron probe microanalysis is presented. The method consists in minimizing the quadratic differences between an experimental spectrum and an analytical function proposed to describe it, by optimizing the parameters involved in the analytical prediction. This algorithm, implemented in the software POEMA (Parameter Optimization in Electron Probe Microanalysis), allows the determination of the elemental concentrations, along with their uncertainties. The method was tested in a set of 159 elemental constituents corresponding to 36 spectra of standards (mostly minerals) that include trace elements. The results were compared with those obtained with the commercial software GENESIS Spectrum® for standardless quantification. The quantifications performed with the method proposed here are better in the 74% of the cases studied. In addition, the performance of the method proposed is compared with the first principles standardless analysis procedure DTSA for a different data set, which excludes trace elements. The relative deviations with respect to the nominal concentrations are lower than 0.04, 0.08 and 0.35 for the 66% of the cases for POEMA, GENESIS and DTSA, respectively. - Highlights: ► A method for standardless quantification in EPMA is presented. ► It gives better results than the commercial software GENESIS Spectrum. ► It gives better results than the software DTSA. ► It allows the determination of the conductive coating thickness. ► It gives an estimation for the concentration uncertainties.

  2. Standardless quantification by parameter optimization in electron probe microanalysis

    Limandri, Silvina P. [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina); Bonetto, Rita D. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco (CINDECA), CONICET, 47 Street 257, (1900) La Plata (Argentina); Facultad de Ciencias Exactas, Universidad Nacional de La Plata, 1 and 47 Streets (1900) La Plata (Argentina); Josa, Victor Galvan; Carreras, Alejo C. [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina); Trincavelli, Jorge C., E-mail: trincavelli@famaf.unc.edu.ar [Instituto de Fisica Enrique Gaviola (IFEG), CONICET (Argentina); Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Medina Allende s/n, (5016) Cordoba (Argentina)

    2012-11-15

    A method for standardless quantification by parameter optimization in electron probe microanalysis is presented. The method consists in minimizing the quadratic differences between an experimental spectrum and an analytical function proposed to describe it, by optimizing the parameters involved in the analytical prediction. This algorithm, implemented in the software POEMA (Parameter Optimization in Electron Probe Microanalysis), allows the determination of the elemental concentrations, along with their uncertainties. The method was tested in a set of 159 elemental constituents corresponding to 36 spectra of standards (mostly minerals) that include trace elements. The results were compared with those obtained with the commercial software GENESIS Spectrum Registered-Sign for standardless quantification. The quantifications performed with the method proposed here are better in the 74% of the cases studied. In addition, the performance of the method proposed is compared with the first principles standardless analysis procedure DTSA for a different data set, which excludes trace elements. The relative deviations with respect to the nominal concentrations are lower than 0.04, 0.08 and 0.35 for the 66% of the cases for POEMA, GENESIS and DTSA, respectively. - Highlights: Black-Right-Pointing-Pointer A method for standardless quantification in EPMA is presented. Black-Right-Pointing-Pointer It gives better results than the commercial software GENESIS Spectrum. Black-Right-Pointing-Pointer It gives better results than the software DTSA. Black-Right-Pointing-Pointer It allows the determination of the conductive coating thickness. Black-Right-Pointing-Pointer It gives an estimation for the concentration uncertainties.

  3. Spider Vein Removal

    Spider veins: How are they removed? I have spider veins on my legs. What options are available ... M.D. Several options are available to remove spider veins — thin red lines or weblike networks of ...

  4. Spider Bites (For Parents)

    ... Videos for Educators Search English Español First Aid: Spider Bites KidsHealth / For Parents / First Aid: Spider Bites ... rare. Signs and Symptoms Of a brown recluse spider bite: red blister in the center with surrounding ...

  5. Spider Bites: First Aid

    ... care immediately if: You were bitten by a black widow or brown recluse spider You are unsure whether the bite ... in the South. Signs and symptoms of a black widow spider bite may include: At ... fever and nausea Brown recluse spider The brown recluse spider has a ...

  6. Optimal numbers of matings: the conditional balance between benefits and costs of mating for females of a nuptial gift-giving spider.

    Toft, S; Albo, M J

    2015-02-01

    In species where females gain a nutritious nuptial gift during mating, the balance between benefits and costs of mating may depend on access to food. This means that there is not one optimal number of matings for the female but a range of optimal mating numbers. With increasing food availability, the optimal number of matings for a female should vary from the number necessary only for fertilization of her eggs to the number needed also for producing these eggs. In three experimental series, the average number of matings for females of the nuptial gift-giving spider Pisaura mirabilis before egg sac construction varied from 2 to 16 with food-limited females generally accepting more matings than well-fed females. Minimal level of optimal mating number for females at satiation feeding conditions was predicted to be 2-3; in an experimental test, the median number was 2 (range 0-4). Multiple mating gave benefits in terms of increased fecundity and increased egg hatching success up to the third mating, and it had costs in terms of reduced fecundity, reduced egg hatching success after the third mating, and lower offspring size. The level of polyandry seems to vary with the female optimum, regulated by a satiation-dependent resistance to mating, potentially leaving satiated females in lifelong virginity. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  7. Optimization of crack detection in steam generator tubes using a punctual probe

    Levy, R.; Ferre, C.

    1985-01-01

    The existence of cracks at the upper end of the expanded zone of a steam generator tube is a recent problem. A differential pencil probe was used for the detection of those cracks with encouraging results. An optimization study has been necessary to solve the difficulties in the evaluation of defects, due to the design of the first probe; the result is a probe making possible a precise analysis of detected signals

  8. Modeling the Insertion Mechanics of Flexible Neural Probes Coated with Sacrificial Polymers for Optimizing Probe Design

    Sagar Singh

    2016-03-01

    Full Text Available Single-unit recording neural probes have significant advantages towards improving signal-to-noise ratio and specificity for signal acquisition in brain-to-computer interface devices. Long-term effectiveness is unfortunately limited by the chronic injury response, which has been linked to the mechanical mismatch between rigid probes and compliant brain tissue. Small, flexible microelectrodes may overcome this limitation, but insertion of these probes without buckling requires supporting elements such as a stiff coating with a biodegradable polymer. For these coated probes, there is a design trade-off between the potential for successful insertion into brain tissue and the degree of trauma generated by the insertion. The objective of this study was to develop and validate a finite element model (FEM to simulate insertion of coated neural probes of varying dimensions and material properties into brain tissue. Simulations were performed to predict the buckling and insertion forces during insertion of coated probes into a tissue phantom with material properties of brain. The simulations were validated with parallel experimental studies where probes were inserted into agarose tissue phantom, ex vivo chick embryonic brain tissue, and ex vivo rat brain tissue. Experiments were performed with uncoated copper wire and both uncoated and coated SU-8 photoresist and Parylene C probes. Model predictions were found to strongly agree with experimental results (<10% error. The ratio of the predicted buckling force-to-predicted insertion force, where a value greater than one would ideally be expected to result in successful insertion, was plotted against the actual success rate from experiments. A sigmoidal relationship was observed, with a ratio of 1.35 corresponding to equal probability of insertion and failure, and a ratio of 3.5 corresponding to a 100% success rate. This ratio was dubbed the “safety factor”, as it indicated the degree to which the coating

  9. Brown Recluse Spider

    ... to a group of spiders commonly known as violin spiders or fiddlebacks. The characteristic fiddle-shaped pattern ... 4-19.1mm) • Color: Golden brown • A dark violin/fiddle shape (see top photo) is located on ...

  10. Nature Study Tips. Spiders.

    Mulaik, Stanley B.

    1990-01-01

    Different types of spiders, their ranges and habits are discussed. Activities associated with the study of spiders are suggested. Four references are listed which may be of interest to beginners. (CW)

  11. Black widow spider

    ... medlineplus.gov/ency/article/002858.htm Black widow spider To use the sharing features on this page, please enable JavaScript. The black widow spider (Latrodectus) has a shiny black body with a ...

  12. An improved model for the oPtImal Measurement Probes Allocation tool

    Sterle, C., E-mail: claudio.sterle@unina.it [Consorzio CREATE/Dipartimento di Ingegneria Elettrica e delle Tecnologie dell’Informazione, Università degli Studi di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Neto, A.C. [Fusion for Energy, 08019 Barcelona (Spain); De Tommasi, G. [Consorzio CREATE/Dipartimento di Ingegneria Elettrica e delle Tecnologie dell’Informazione, Università degli Studi di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy)

    2015-10-15

    Highlights: • The problem of optimally allocating the probes of a diagnostic system is tackled. • The problem is decomposed in two consecutive optimization problems. • Two original ILP models are proposed and sequentially solved to optimality. • The proposed ILP models improve and extend the previous work present in literature. • Real size instances have been optimally solved with very low computation time. - Abstract: The oPtImal Measurement Probes Allocation (PIMPA) tool has been recently proposed in [1] to maximize the reliability of a tokamak diagnostic system against the failure of one or more of the processing nodes. PIMPA is based on the solution of integer linear programming (ILP) problems, and it minimizes the effect of the failure of a data acquisition component. The first formulation of the PIMPA model did not support the concept of individual slots. This work presents an improved ILP model that addresses the above mentioned problem, by taking into account all the individual probes.

  13. An improved model for the oPtImal Measurement Probes Allocation tool

    Sterle, C.; Neto, A.C.; De Tommasi, G.

    2015-01-01

    Highlights: • The problem of optimally allocating the probes of a diagnostic system is tackled. • The problem is decomposed in two consecutive optimization problems. • Two original ILP models are proposed and sequentially solved to optimality. • The proposed ILP models improve and extend the previous work present in literature. • Real size instances have been optimally solved with very low computation time. - Abstract: The oPtImal Measurement Probes Allocation (PIMPA) tool has been recently proposed in [1] to maximize the reliability of a tokamak diagnostic system against the failure of one or more of the processing nodes. PIMPA is based on the solution of integer linear programming (ILP) problems, and it minimizes the effect of the failure of a data acquisition component. The first formulation of the PIMPA model did not support the concept of individual slots. This work presents an improved ILP model that addresses the above mentioned problem, by taking into account all the individual probes.

  14. Did You Say Spiders?

    Campbell, Alene

    This spider unit focuses on students' development of cooperative learning and inquiry-based skills. Students read "The Very Busy Spider" by Eric Carle, and then work in cooperative groups using the Internet to research and synthesize important information about spiders. Technology is used for vocabulary instruction and to create a…

  15. Learned predation risk management by spider mites

    Thomas eHackl

    2014-09-01

    Full Text Available Predation is a prime selective force shaping prey behavior. Investment in anti-predator behavior is traded-off against time and energy for other fitness-enhancing activities such as foraging or reproduction. To optimize this benefit/cost trade-off, prey should be able to innately and/or by experience modulate their behavior to the level of predation risk. Here, we assessed learned predation risk management in the herbivorous two-spotted spider mite Tetranychus urticae. We exposed spider mites coming from benign (naïve or high immediate predation risk (experienced environments to latent and/or no risk and assessed their site choice, activity and oviposition. Benign environments were characterized by the absence of any predator cues, high immediate risk environments by killed spider mites, physical presence of the predatory mite Phytoseiulus persimilis and associated chemosensory traces left on the surface, and latent risk environments by only predator traces. In the no-choice experiment both naïve and experienced spider mites laid their first egg later on leaves with than without predator traces. Irrespective of predator traces presence/absence, experienced mites laid their first egg earlier than naïve ones did. Naïve spider mites were more active, indicating higher restlessness, and laid fewer eggs on leaves with predator traces, whereas experienced mites were less active and laid similar numbers of eggs on leaves with and without predator traces. In the choice experiment both naïve and experienced spider mites preferentially resided and oviposited on leaves without predator traces but experienced mites were less active than naïve ones. Overall, our study suggests that spider mites experienced with high predation risk behave bolder under latent risk than naïve spider mites. Since predator traces alone do not indicate immediate risk, we argue that the attenuated anti-predator response of experienced spider mites represents adaptive learned

  16. Spiders in dermatology.

    Kang, Jun K; Bhate, Chinmoy; Schwartz, Robert A

    2014-09-01

    Spider bites represent an unusual and potentially over-represented clinical diagnosis. Despite a common fear of spiders, known as arachnophobia, current knowledge suggests that only a small number of families within the order Araneae are medically relevant. Moreover, most cutaneous spider reactions, including both evenomations and physical trauma, produce mild, local symptoms which may be managed with supportive care alone. The differential diagnosis for spider bites may be broad, especially if the offending arachnid is not seen or found. We describe a series of spiders relevant to the dermatologist in the United States.

  17. Differential predictive power of self report and implicit measures on behavioural and physiological fear responses to spiders

    van Bockstaele, B.; Verschuere, B.; Koster, E.H.W.; Tibboel, H.; de Houwer, J.; Crombez, G.

    2011-01-01

    In this study, we investigated to what extent indirect measures predict behavioural and physiological fear responses towards spiders. Implicit attitudes towards spiders were assessed using an implicit association test and attentional bias towards spiders was assessed using a dot probe task and a

  18. Probing Entanglement in Adiabatic Quantum Optimization with Trapped Ions

    Philipp eHauke

    2015-04-01

    Full Text Available Adiabatic quantum optimization has been proposed as a route to solve NP-complete problems, with a possible quantum speedup compared to classical algorithms. However, the precise role of quantum effects, such as entanglement, in these optimization protocols is still unclear. We propose a setup of cold trapped ions that allows one to quantitatively characterize, in a controlled experiment, the interplay of entanglement, decoherence, and non-adiabaticity in adiabatic quantum optimization. We show that, in this way, a broad class of NP-complete problems becomes accessible for quantum simulations, including the knapsack problem, number partitioning, and instances of the max-cut problem. Moreover, a general theoretical study reveals correlations of the success probability with entanglement at the end of the protocol. From exact numerical simulations for small systems and linear ramps, however, we find no substantial correlations with the entanglement during the optimization. For the final state, we derive analytically a universal upper bound for the success probability as a function of entanglement, which can be measured in experiment. The proposed trapped-ion setups and the presented study of entanglement address pertinent questions of adiabatic quantum optimization, which may be of general interest across experimental platforms.

  19. Attending to detail by communal spider-eating spiders.

    Jackson, Robert R; Nelson, Ximena J

    2012-07-01

    Communal predators may often need to make especially intricate foraging decisions, as a predator's success may depend on the actions of its neighbours. Here,we consider the decisions made by Portia africana, a jumping spider (Salticidae) that preys on other spiders, including Oecobius amboseli (Oecobiidae), a small prey spider that lives under small sheets of silk (nests) on the walls of buildings. P. africana juveniles settle near oecobiid nests and then ambush oecobiids as they leave or enter the nest. Two or more P. africana juveniles sometimes settle at the same nest and, when an oecobiid is captured, the P. africana juveniles may share the meal. We investigated the joining decisions made by naïve P. africana juveniles. Experiments were based on using lures (dead spiders positioned in lifelike posture) arranged in a series of 17 different scenes defined by the presence/absence of a nest, the lure types present and the configuration of the lures and the nest. Our findings imply that P. africana juveniles make remarkably precise predatory decisions, with the variables that matter including whether a nest is present, the identity of spiders inside and outside a nest and how spiders are positioned relative to each other and the nest.

  20. Optimization of Actinide Quantification by Electron Probe Microanalysis

    Moy, A.; Merlet, C.; Llovet, X.; Dugne, O.

    2013-06-01

    Conventional quantitative electron probe microanalysis of actinides requires the use of reference standard samples. However, for such elements, standards are generally not available. To overcome this difficulty, standard-less methods of analysis are used, in which the x-ray intensity emitted by the standard is calculated. To be reliable, such calculations require accurate knowledge of physical data such as the x-ray production cross section. However, experimental data of this quantity are not always available for actinide elements. In the present work, experimental L and M x-ray production cross sections were measured for elements uranium and lead. Measurements were performed with two electron microprobes using wavelength-dispersive spectrometers using thin self-supporting targets. Experimental results are compared with calculated cross sections obtained from different analytical formulae, and, whenever possible, with experimental data obtained from the literature. (authors)

  1. Funnel-web spider bite

    ... page: //medlineplus.gov/ency/article/002844.htm Funnel-web spider bite To use the sharing features on ... the effects of a bite from the funnel-web spider. Male funnel-web spiders are more poisonous ...

  2. Degree of Biomimicry of Artificial Spider Silk Spinning Assessed by NMR Spectroscopy.

    Otikovs, Martins; Andersson, Marlene; Jia, Qiupin; Nordling, Kerstin; Meng, Qing; Andreas, Loren B; Pintacuda, Guido; Johansson, Jan; Rising, Anna; Jaudzems, Kristaps

    2017-10-02

    Biomimetic spinning of artificial spider silk requires that the terminal domains of designed minispidroins undergo specific structural changes in concert with the β-sheet conversion of the repetitive region. Herein, we combine solution and solid-state NMR methods to probe domain-specific structural changes in the NT2RepCT minispidroin, which allows us to assess the degree of biomimicry of artificial silk spinning. In addition, we show that the structural effects of post-spinning procedures can be examined. By studying the impact of NT2RepCT fiber drying, we observed a reversible beta-to-alpha conversion. We think that this approach will be useful for guiding the optimization of artificial spider silk fibers. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Spiders in caves.

    Mammola, Stefano; Isaia, Marco

    2017-04-26

    World experts of different disciplines, from molecular biology to macro-ecology, recognize the value of cave ecosystems as ideal ecological and evolutionary laboratories. Among other subterranean taxa, spiders stand out as intriguing model organisms for their ecological role of top predators, their unique adaptations to the hypogean medium and their sensitivity to anthropogenic disturbance. As the description of the first eyeless spider ( Stalita taenaria ), an array of papers on subterranean spider biology, ecology and evolution has been published, but a comprehensive review on these topics is still lacking. We provide a general overview of the spider families recorded in hypogean habitats worldwide, we review the different adaptations of hypogean spiders to subterranean life, and we summarize the information gathered so far about their origin, population structure, ecology and conservation status. Finally, we point out the limits of the knowledge we currently have regarding hypogean spiders, aiming to stimulate future research. © 2017 The Author(s).

  4. Optimal Strategies for Probing Terrestrial Exoplanet Atmospheres with JWST

    Batalha, Natasha E.; Lewis, Nikole K.; Line, Michael

    2018-01-01

    It is imperative that the exoplanet community determines the feasibility and the resources needed to yield high fidelity atmospheric compositions from terrestrial exoplanets. In particular, LHS 1140b and the TRAPPIST-1 system, already slated for observations by JWST’s Guaranteed Time Observers, will be the first two terrestrial planets observed by JWST. I will discuss optimal observing strategies for observing these two systems, focusing on the NIRSpec Prism (1-5μm) and the combination of NIRISS SOSS (1-2.7μm) and NIRSpec G395H (3-5μm). I will also introduce currently unsupported JWST readmodes that have the potential to greatly increase the precision on our atmospheric spectra. Lastly, I will use information content theory to compute the expected confidence interval on the retrieved abundances of key molecular species and temperature profiles as a function of JWST observing cycles.

  5. Optimization of Comb-Drive Actuators [Nanopositioners for probe-based data storage and musical MEMS

    Engelen, Johannes Bernardus Charles

    2011-01-01

    The era of infinite storage seems near. To reach it, data storage capabilities need to grow, and new storage technologies must be developed.This thesis studies one aspect of one of the emergent storage technologies: optimizing electrostatic combdrive actuation for a parallel probe-based data storage

  6. Respiration in spiders (Araneae).

    Schmitz, Anke

    2016-05-01

    Spiders (Araneae) are unique regarding their respiratory system: they are the only animal group that breathe simultaneously with lungs and tracheae. Looking at the physiology of respiration the existence of tracheae plays an important role in spiders with a well-developed tracheal system. Other factors as sex, life time, type of prey capture and the high ability to gain energy anaerobically influence the resting and the active metabolic rate intensely. Most spiders have metabolic rates that are much lower than expected from body mass; but especially those with two pairs of lungs. Males normally have higher resting rates than females; spiders that are less evolved and possess a cribellum have lower metabolic rates than higher evolved species. Freely hunting spiders show a higher energy turnover than spiders hunting with a web. Spiders that live longer than 1 year will have lower metabolic rates than those species that die after 1 year in which development and reproduction must be completed. Lower temperatures and starvation, which most spiders can cope with, will decrease the metabolic rate as well.

  7. Bat Predation by Spiders

    Nyffeler, Martin; Knörnschild, Mirjam

    2013-01-01

    In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (∼90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed. PMID:23516436

  8. Bat predation by spiders.

    Nyffeler, Martin; Knörnschild, Mirjam

    2013-01-01

    In this paper more than 50 incidences of bats being captured by spiders are reviewed. Bat-catching spiders have been reported from virtually every continent with the exception of Antarctica (≈ 90% of the incidences occurring in the warmer areas of the globe between latitude 30° N and 30° S). Most reports refer to the Neotropics (42% of observed incidences), Asia (28.8%), and Australia-Papua New Guinea (13.5%). Bat-catching spiders belong to the mygalomorph family Theraphosidae and the araneomorph families Nephilidae, Araneidae, and Sparassidae. In addition to this, an attack attempt by a large araneomorph hunting spider of the family Pisauridae on an immature bat was witnessed. Eighty-eight percent of the reported incidences of bat catches were attributable to web-building spiders and 12% to hunting spiders. Large tropical orb-weavers of the genera Nephila and Eriophora in particular have been observed catching bats in their huge, strong orb-webs (of up to 1.5 m diameter). The majority of identifiable captured bats were small aerial insectivorous bats, belonging to the families Vespertilionidae (64%) and Emballonuridae (22%) and usually being among the most common bat species in their respective geographic area. While in some instances bats entangled in spider webs may have died of exhaustion, starvation, dehydration, and/or hyperthermia (i.e., non-predation death), there were numerous other instances where spiders were seen actively attacking, killing, and eating the captured bats (i.e., predation). This evidence suggests that spider predation on flying vertebrates is more widespread than previously assumed.

  9. Biomechanics of Spider Silks

    2006-03-02

    water and deformation conditions. Such fibres [Nexia ’ biosteel ’ silk ] were spun from recombinant silk ’cloned’ from Spidroin II and indeed show 67...SUBTITLE 5. FUNDING NUMBERS Biomechanics of Spider Silks F49620-03-1-0111 6. AUTHOR(S) Fritz Vollrath 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES...Perform Pro, WHSIDIOR, Oct 94 COVER SHEET FINAL (3rd Year) Report to AFOSR on: BIOMECHANICS OF SPIDER SILKS Fritz Vollrath, Oxford University, England

  10. Spider fauna of semiarid eastern Colorado agroecosystems: diversity, abundance, and effects of crop intensification.

    Kerzicnik, Lauren M; Peairs, Frank B; Cushing, Paula E; Draney, Michael L; Merrill, Scott C

    2013-02-01

    Spiders are critical predators in agroecosystems. Crop management practices can influence predator density and diversity, which, in turn, can influence pest management strategies. Crop intensification is a sustainable agricultural technique that can enhance crop production although optimizing soil moisture. To date, there is no information on how crop intensification affects natural enemy populations, particularly spiders. This study had two objectives: to characterize the abundance and diversity of spiders in eastern Colorado agroecosystems, and to test the hypothesis that spider diversity and density would be higher in wheat (Triticum aestivum L.) in crop-intensified rotations compared with wheat in conventional rotations. We collected spiders through pitfall, vacuum, and lookdown sampling from 2002 to 2007 to test these objectives. Over 11,000 spiders in 19 families from 119 species were captured from all sampling techniques. Interestingly, the hunting spider guild represented 89% of the spider fauna captured from all sites with the families Gnaphosidae and Lycosidae representing 75% of these spiders. Compared with European agroecosystems, these agroecosystems had greater diversity, which can be beneficial for the biological control of pests. Overall, spider densities were low in these semiarid cropping systems, and crop intensification effects on spider densities were not evident at this scale.

  11. Optimizing Filter-Probe Diffusion Weighting in the Rat Spinal Cord for Human Translation

    Matthew D. Budde

    2017-12-01

    Full Text Available Diffusion tensor imaging (DTI is a promising biomarker of spinal cord injury (SCI. In the acute aftermath, DTI in SCI animal models consistently demonstrates high sensitivity and prognostic performance, yet translation of DTI to acute human SCI has been limited. In addition to technical challenges, interpretation of the resulting metrics is ambiguous, with contributions in the acute setting from both axonal injury and edema. Novel diffusion MRI acquisition strategies such as double diffusion encoding (DDE have recently enabled detection of features not available with DTI or similar methods. In this work, we perform a systematic optimization of DDE using simulations and an in vivo rat model of SCI and subsequently implement the protocol to the healthy human spinal cord. First, two complementary DDE approaches were evaluated using an orientationally invariant or a filter-probe diffusion encoding approach. While the two methods were similar in their ability to detect acute SCI, the filter-probe DDE approach had greater predictive power for functional outcomes. Next, the filter-probe DDE was compared to an analogous single diffusion encoding (SDE approach, with the results indicating that in the spinal cord, SDE provides similar contrast with improved signal to noise. In the SCI rat model, the filter-probe SDE scheme was coupled with a reduced field of view (rFOV excitation, and the results demonstrate high quality maps of the spinal cord without contamination from edema and cerebrospinal fluid, thereby providing high sensitivity to injury severity. The optimized protocol was demonstrated in the healthy human spinal cord using the commercially-available diffusion MRI sequence with modifications only to the diffusion encoding directions. Maps of axial diffusivity devoid of CSF partial volume effects were obtained in a clinically feasible imaging time with a straightforward analysis and variability comparable to axial diffusivity derived from DTI

  12. A general framework for optimization of probes for gene expression microarray and its application to the fungus Podospora anserina.

    Bidard, Frédérique; Imbeaud, Sandrine; Reymond, Nancie; Lespinet, Olivier; Silar, Philippe; Clavé, Corinne; Delacroix, Hervé; Berteaux-Lecellier, Véronique; Debuchy, Robert

    2010-06-18

    The development of new microarray technologies makes custom long oligonucleotide arrays affordable for many experimental applications, notably gene expression analyses. Reliable results depend on probe design quality and selection. Probe design strategy should cope with the limited accuracy of de novo gene prediction programs, and annotation up-dating. We present a novel in silico procedure which addresses these issues and includes experimental screening, as an empirical approach is the best strategy to identify optimal probes in the in silico outcome. We used four criteria for in silico probe selection: cross-hybridization, hairpin stability, probe location relative to coding sequence end and intron position. This latter criterion is critical when exon-intron gene structure predictions for intron-rich genes are inaccurate. For each coding sequence (CDS), we selected a sub-set of four probes. These probes were included in a test microarray, which was used to evaluate the hybridization behavior of each probe. The best probe for each CDS was selected according to three experimental criteria: signal-to-noise ratio, signal reproducibility, and representative signal intensities. This procedure was applied for the development of a gene expression Agilent platform for the filamentous fungus Podospora anserina and the selection of a single 60-mer probe for each of the 10,556 P. anserina CDS. A reliable gene expression microarray version based on the Agilent 44K platform was developed with four spot replicates of each probe to increase statistical significance of analysis.

  13. A general framework for optimization of probes for gene expression microarray and its application to the fungus Podospora anserina

    Bidard Frédérique

    2010-06-01

    Full Text Available Abstract Background The development of new microarray technologies makes custom long oligonucleotide arrays affordable for many experimental applications, notably gene expression analyses. Reliable results depend on probe design quality and selection. Probe design strategy should cope with the limited accuracy of de novo gene prediction programs, and annotation up-dating. We present a novel in silico procedure which addresses these issues and includes experimental screening, as an empirical approach is the best strategy to identify optimal probes in the in silico outcome. Findings We used four criteria for in silico probe selection: cross-hybridization, hairpin stability, probe location relative to coding sequence end and intron position. This latter criterion is critical when exon-intron gene structure predictions for intron-rich genes are inaccurate. For each coding sequence (CDS, we selected a sub-set of four probes. These probes were included in a test microarray, which was used to evaluate the hybridization behavior of each probe. The best probe for each CDS was selected according to three experimental criteria: signal-to-noise ratio, signal reproducibility, and representative signal intensities. This procedure was applied for the development of a gene expression Agilent platform for the filamentous fungus Podospora anserina and the selection of a single 60-mer probe for each of the 10,556 P. anserina CDS. Conclusions A reliable gene expression microarray version based on the Agilent 44K platform was developed with four spot replicates of each probe to increase statistical significance of analysis.

  14. Progresses in optimization strategy for radiolabeled molecular probes targeting integrin αvβ3

    Chen Haojun; Wu Hua

    2012-01-01

    Tumor angiogenesis is critical in the growth, invasion and metastasis of malignant tumors. The integrins, which express on many types of tumor cells and activated vascular endothelial cells, play an important role in regulation of the tumor angiogenesis. RGD peptide, which contains Arg-Gly-Asp sequence, binds specifically to integrin α v β 3 . Therefore, the radiolabeled RGD peptides may have broad application prospects in radionuclide imaging and therapy. Major research interests include the selection of radionuclides, modification and improvement of RGD structures. In this article, we give a review on research progresses in optimization strategy for radiolabeled molecular probes targeting integrin α v β 3 . (authors)

  15. Silk Spinning in Silkworms and Spiders.

    Andersson, Marlene; Johansson, Jan; Rising, Anna

    2016-08-09

    Spiders and silkworms spin silks that outcompete the toughness of all natural and manmade fibers. Herein, we compare and contrast the spinning of silk in silkworms and spiders, with the aim of identifying features that are important for fiber formation. Although spiders and silkworms are very distantly related, some features of spinning silk seem to be universal. Both spiders and silkworms produce large silk proteins that are highly repetitive and extremely soluble at high pH, likely due to the globular terminal domains that flank an intermediate repetitive region. The silk proteins are produced and stored at a very high concentration in glands, and then transported along a narrowing tube in which they change conformation in response primarily to a pH gradient generated by carbonic anhydrase and proton pumps, as well as to ions and shear forces. The silk proteins thereby convert from random coil and alpha helical soluble conformations to beta sheet fibers. We suggest that factors that need to be optimized for successful production of artificial silk proteins capable of forming tough fibers include protein solubility, pH sensitivity, and preservation of natively folded proteins throughout the purification and initial spinning processes.

  16. Optimized Fast-FISH with a-satellite probes: acceleration by microwave activation

    Durm M.

    1997-01-01

    Full Text Available It has been shown for several DNA probes that the recently introduced Fast-FISH (fluorescence in situ hybridization technique is well suited for quantitative microscopy. For highly repetitive DNA probes the hybridization (renaturation time and the number of subsequent washing steps were reduced considerably by omitting denaturing chemical agents (e.g., formamide. The appropriate hybridization temperature and time allow a clear discrimination between major and minor binding sites by quantitative fluorescence microscopy. The well-defined physical conditions for hybridization permit automatization of the procedure, e.g., by a programmable thermal cycler. Here, we present optimized conditions for a commercially available X-specific a-satellite probe. Highly fluorescent major binding sites were obtained for 74oC hybridization temperature and 60 min hybridization time. They were clearly discriminated from some low fluorescent minor binding sites on metaphase chromosomes as well as in interphase cell nuclei. On average, a total of 3.43 ± 1.59 binding sites were measured in metaphase spreads, and 2.69 ± 1.00 in interphase nuclei. Microwave activation for denaturation and hybridization was tested to accelerate the procedure. The slides with the target material and the hybridization buffer were placed in a standard microwave oven. After denaturation for 20 s at 900 W, hybridization was performed for 4 min at 90 W. The suitability of a microwave oven for Fast-FISH was confirmed by the application to a chromosome 1-specific a-satellite probe. In this case, denaturation was performed at 630 W for 60 s and hybridization at 90 W for 5 min. In all cases, the results were analyzed quantitatively and compared to the results obtained by Fast-FISH. The major binding sites were clearly discriminated by their brightness

  17. Probing optimal measurement configuration for optical scatterometry by the multi-objective genetic algorithm

    Chen, Xiuguo; Gu, Honggang; Jiang, Hao; Zhang, Chuanwei; Liu, Shiyuan

    2018-04-01

    Measurement configuration optimization (MCO) is a ubiquitous and important issue in optical scatterometry, whose aim is to probe the optimal combination of measurement conditions, such as wavelength, incidence angle, azimuthal angle, and/or polarization directions, to achieve a higher measurement precision for a given measuring instrument. In this paper, the MCO problem is investigated and formulated as a multi-objective optimization problem, which is then solved by the multi-objective genetic algorithm (MOGA). The case study on the Mueller matrix scatterometry for the measurement of a Si grating verifies the feasibility of the MOGA in handling the MCO problem in optical scatterometry by making a comparison with the Monte Carlo simulations. Experiments performed at the achieved optimal measurement configuration also show good agreement between the measured and calculated best-fit Mueller matrix spectra. The proposed MCO method based on MOGA is expected to provide a more general and practical means to solve the MCO problem in the state-of-the-art optical scatterometry.

  18. Species richness and composition assessment of spiders in a Mediterranean scrubland

    Bondoso Cardoso, Pedro Miguel; Henriques, Sérgio S.; Gaspar, Clara

    2009-01-01

    Intensive fieldwork has been undertaken in Portugal in order to develop a standardized and optimized sampling protocol for Mediterranean spiders. The present study had the objectives of testing the use of semi-quantitative sampling for obtaining an exhaustive species richness assessment of spiders...

  19. The Spider Files

    McDonald, James; Dominguez, Lynn

    2012-01-01

    As children develop misconceptions about animals they believe are dangerous, they also adopt attitudes that are difficult to change. Changing these attitudes is challenging for teachers. One animal that is easy to find but difficult for children to understand is a spider. As with most wild animals, they are difficult to teach about because…

  20. PATHWAYS TO SPIDER PHOBIA

    MERCKELBACH, H; ARNTZ, A; ARRINDELL, WA; DEJONG, PJ

    Using a revised version of the Phobic Origin Questionnaire (POQ; Ost, L. G. & Hugdahl, K. Behaviour Research and Therapy, 19,439-477; 1981), the present study examined whether conditioning experiences, modeling experiences, and/or informational learning experiences were more often reported by spider

  1. Spider Web Pattern

    2006-01-01

    A delicate pattern, like that of a spider web, appears on top of the Mars residual polar cap, after the seasonal carbon-dioxide ice slab has disappeared. Next spring, these will likely mark the sites of vents when the carbon-dioxide ice cap returns. This Mars Global Surveyor, Mars Orbiter Camera image is about 3-kilometers wide (2-miles).

  2. Progress on development of SPIDER diagnostics

    Pasqualotto, R.; Agostini, M.; Barbisan, M.; Bernardi, M.; Brombin, M.; Cavazzana, R.; Croci, G.; Palma, M. Dalla; Delogu, R. S.; Gorini, G.; Lotto, L.; Muraro, A.; Peruzzo, S.; Pimazzoni, A.; Pomaro, N.; Rizzolo, A.; Serianni, G.; Spolaore, M.; Tardocchi, M.; Zaniol, B.; Zaupa, M.

    2017-08-01

    SPIDER experiment, the full size prototype of the beam source for the ITER heating neutral beam injector, has to demonstrate extraction and acceleration to 100 kV of a large negative ion hydrogen or deuterium beam with co-extracted electron fraction e-/D- SPIDER plant systems are being installed, the different diagnostic systems are in the procurement phase. Their final design is described here with a focus on some key solutions and most original and cost effective implementations. Thermocouples used to measure the power load distribution in the source and over the beam dump front surface will be efficiently fixed with proven technique and acquired through commercial and custom electronics. Spectroscopy needs to use well collimated lines of sight and will employ novel design spectrometers with higher efficiency and resolution and filtered detectors with custom built amplifiers. The electrostatic probes will be operated through electronics specifically developed to cope with the challenging environment of the RF source. The instrumented calorimeter STRIKE will use new CFC tiles, still under development. Two linear cameras, one built in house, have been tested as suitable for optical beam tomography. Some diagnostic components are off the shelf, others are custom developed: some of these are being prototyped or are under test before final production and installation, which will be completed before start of SPIDER operation.

  3. Spider-Ant Associations: An Updated Review of Myrmecomorphy, Myrmecophily, and Myrmecophagy in Spiders

    Paula E. Cushing

    2012-01-01

    Full Text Available This paper provides a summary of the extensive theoretical and empirical work that has been carried out in recent years testing the adaptational significance of various spider-ant associations. Hundreds of species of spiders have evolved close relationships with ants and can be classified as myrmecomorphs, myrmecophiles, or myrmecophages. Myrmecomorphs are Batesian mimics. Their close morphological and behavioral resemblance to ants confers strong survival advantages against visually hunting predators. Some species of spiders have become integrated into the ant society as myrmecophiles or symbionts. These spider myrmecophiles gain protection against their own predators, live in an environment with a stable climate, and are typically surrounded by abundant food resources. The adaptations by which this integration is made possible are poorly known, although it is hypothesized that most spider myrmecophiles are chemical mimics and some are even phoretic on their hosts. The third type of spider-ant association discussed is myrmecophagy—or predatory specialization on ants. A table of known spider myrmecophages is provided as is information on their biology and hunting strategies. Myrmecophagy provides these predators with an essentially unlimited food supply and may even confer other protections to the spiders.

  4. Physical characterization of functionalized spider silk: electronic and sensing properties

    Eden Steven, Jin Gyu Park, Anant Paravastu, Elsa Branco Lopes, James S Brooks, Ongi Englander, Theo Siegrist, Papatya Kaner and Rufina G Alamo

    2011-01-01

    Full Text Available This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline and amorphous (helical structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 °C, has a strong effect on the morphology of silk bundles (increasing their size, on the process of pyrolization (suppressing mass loss rates and on the resulting carbonized fiber structure (that becomes more robust against bending and strain. The effects of iodine doping and other functional parameters (vacuum and thin film coating motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof

  5. Physical characterization of functionalized spider silk: electronic and sensing properties

    Steven, Eden; Brooks, James S [Department of Physics and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Park, Jin Gyu [FAMU-FSU Department of Industrial and Manufacturing Engineering, High-Performance Materials Institute, Florida State University, 2005 Levy Ave., Tallahassee, FL 32310 (United States); Paravastu, Anant; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G [FAMU-FSU Department of Chemical and Biomedical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, FL 32310 (United States); Branco Lopes, Elsa [Departamento de Quimica, Instituto Tecnologico e Nuclear/CFMC-UL, P-2686-953 Sacavem (Portugal); Englander, Ongi, E-mail: esteven@magnet.fsu.edu [FAMU-FSU Department of Mechanical Engineering and National High Magnetic Field Laboratory, Florida State University, 1800 East Paul Dirac, Tallahassee, Florida 32310 (United States)

    2011-10-15

    This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of {beta}-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 deg. C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and {beta}-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of {beta}-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof

  6. Physical characterization of functionalized spider silk: electronic and sensing properties

    Steven, Eden; Brooks, James S; Park, Jin Gyu; Paravastu, Anant; Siegrist, Theo; Kaner, Papatya; Alamo, Rufina G; Branco Lopes, Elsa; Englander, Ongi

    2011-01-01

    This work explores functional, fundamental and applied aspects of naturally harvested spider silk fibers. Natural silk is a protein polymer where different amino acids control the physical properties of fibroin bundles, producing, for example, combinations of β-sheet (crystalline) and amorphous (helical) structural regions. This complexity presents opportunities for functional modification to obtain new types of material properties. Electrical conductivity is the starting point of this investigation, where the insulating nature of neat silk under ambient conditions is described first. Modification of the conductivity by humidity, exposure to polar solvents, iodine doping, pyrolization and deposition of a thin metallic film are explored next. The conductivity increases exponentially with relative humidity and/or solvent, whereas only an incremental increase occurs after iodine doping. In contrast, iodine doping, optimal at 70 deg. C, has a strong effect on the morphology of silk bundles (increasing their size), on the process of pyrolization (suppressing mass loss rates) and on the resulting carbonized fiber structure (that becomes more robust against bending and strain). The effects of iodine doping and other functional parameters (vacuum and thin film coating) motivated an investigation with magic angle spinning nuclear magnetic resonance (MAS-NMR) to monitor doping-induced changes in the amino acid-protein backbone signature. MAS-NMR revealed a moderate effect of iodine on the helical and β-sheet structures, and a lesser effect of gold sputtering. The effects of iodine doping were further probed by Fourier transform infrared (FTIR) spectroscopy, revealing a partial transformation of β-sheet-to-amorphous constituency. A model is proposed, based on the findings from the MAS-NMR and FTIR, which involves iodine-induced changes in the silk fibroin bundle environment that can account for the altered physical properties. Finally, proof-of-concept applications of

  7. Extended spider cognition.

    Japyassú, Hilton F; Laland, Kevin N

    2017-05-01

    There is a tension between the conception of cognition as a central nervous system (CNS) process and a view of cognition as extending towards the body or the contiguous environment. The centralised conception requires large or complex nervous systems to cope with complex environments. Conversely, the extended conception involves the outsourcing of information processing to the body or environment, thus making fewer demands on the processing power of the CNS. The evolution of extended cognition should be particularly favoured among small, generalist predators such as spiders, and here, we review the literature to evaluate the fit of empirical data with these contrasting models of cognition. Spiders do not seem to be cognitively limited, displaying a large diversity of learning processes, from habituation to contextual learning, including a sense of numerosity. To tease apart the central from the extended cognition, we apply the mutual manipulability criterion, testing the existence of reciprocal causal links between the putative elements of the system. We conclude that the web threads and configurations are integral parts of the cognitive systems. The extension of cognition to the web helps to explain some puzzling features of spider behaviour and seems to promote evolvability within the group, enhancing innovation through cognitive connectivity to variable habitat features. Graded changes in relative brain size could also be explained by outsourcing information processing to environmental features. More generally, niche-constructed structures emerge as prime candidates for extending animal cognition, generating the selective pressures that help to shape the evolving cognitive system.

  8. Animal coloration: sexy spider scales.

    Taylor, Lisa A; McGraw, Kevin J

    2007-08-07

    Many male jumping spiders display vibrant colors that are used in visual communication. A recent microscopic study on a jumping spider from Singapore shows that three-layered 'scale sandwiches' of chitin and air are responsible for producing their brilliant iridescent body coloration.

  9. Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders

    Llandres, Ana L.; Rodríguez-Gironés, Miguel A.

    2011-01-01

    According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees. PMID:21359183

  10. Spider movement, UV reflectance and size, but not spider crypsis, affect the response of honeybees to Australian crab spiders.

    Llandres, Ana L; Rodríguez-Gironés, Miguel A

    2011-02-16

    According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees.

  11. A spider elevator

    Butylkin, A.V.; Butylkin, V.A.; Izosimov, A.M.

    1983-01-01

    A spider elevator is proposed which contains a body, a wedge clamp with wedges hinged to each other, a subassembly for holding the wedge clamp in the open and closed positions and a mechanism for changing the wedge clamp, which is made in the form of levers with ears for cleats and installed in the body with the capability of turning. To increase reliability in the operational mode through using the external force for clamping the pipe, the free ends of the levers are hinged with the body by a power cylinder.

  12. Final design of thermal diagnostic system in SPIDER ion source

    Brombin, M., E-mail: matteo.brombin@igi.cnr.it; Dalla Palma, M.; Pasqualotto, R.; Pomaro, N. [Consorzio RFX, Corso Stati Uniti 4, I-35127 Padova (Italy)

    2016-11-15

    The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H{sup −} production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements. This paper deals with the final design and the technical specification of the thermal sensor diagnostic for SPIDER. In particular the layout of the diagnostic, together with the sensors distribution in the different components, the cables routing and the conditioning and acquisition cubicles are described.

  13. Spider Silk Processing for Spidroin Recovery from Crossopriza Lyoni Web

    Mohtar, J. A.; Ooi, W. L.; Yusuf, F.

    2018-03-01

    Spider silk is a potential biomaterial that can be used in various applications for its outstanding physicomechanical properties attributed by the spidroin composition. Efforts for commercializing spider silks have been mainly focused on the characterization of spidroins from the Entelegyne spiders for exceptional fibre construction. Hence, studies on silk proteins from the Haplogyne species remain neglected. The aim of this study is to isolate spidroin from Crossopriza lyoni web. Silk processing involved the pretreatment of fibres for the shell layer removal from the surface. A screening study was conducted to analyze the effect of temperature, incubation time and agitation speed on spidroin extraction using Ajisawa’s reagent by OFAT analysis followed by statistical optimization of the extraction process via RSM for maximal protein recovery. All parameters exerted significant effect on spidroin recovery (pspider silk to meet the demand for a variety of silk-based products in the near future.

  14. Final design of thermal diagnostic system in SPIDER ion source

    Brombin, M.; Dalla Palma, M.; Pasqualotto, R.; Pomaro, N.

    2016-01-01

    The prototype radio frequency source of the ITER heating neutral beams will be first tested in SPIDER test facility to optimize H"− production, cesium dynamics, and overall plasma characteristics. Several diagnostics will allow to fully characterise the beam in terms of uniformity and divergence and the source, besides supporting a safe and controlled operation. In particular, thermal measurements will be used for beam monitoring and system protection. SPIDER will be instrumented with mineral insulated cable thermocouples, both on the grids, on other components of the beam source, and on the rear side of the beam dump water cooled elements. This paper deals with the final design and the technical specification of the thermal sensor diagnostic for SPIDER. In particular the layout of the diagnostic, together with the sensors distribution in the different components, the cables routing and the conditioning and acquisition cubicles are described.

  15. Analysis for the brazing deformation of AFA3G spider

    Lin Feng

    2015-01-01

    Spider, the key component of the AFA3G cluster control assemblies (RCCA), is brazed with body, vanes and fingers. Vacuum brazing is crucial in the spider process and it is directly relevant to the final product quality. This paper analyze the deformation of the AFA3G spider in vacuum brazing procedure based on a large amount of data. The results indicate that the parallelism of the finger is most affected by the brazing and its deformation has obvious regularity. Deformation is mainly caused by the different contraction directions of components along with the interactions among them during cooling process. An optimized design of the brazing fixture based on the regularity and the value of the deformation greatly improves the parallelism of the fingers. Besides, the vacuum brazing procedure also affects the hole diameter of the finger, however, we could reduce the deformation by using columnar pin on the brazing fixture. (author)

  16. Spiders from Mars?

    2003-01-01

    MGS MOC Release No. MOC2-426, 19 July 2003No, this is not a picture of a giant, martian spider web. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a plethora of polygonal features on the floor of a northern hemisphere impact crater near 65.6oN, 327.7oW. The picture was acquired during spring, after the seasonal carbon dioxide frost cap had largely migrated through the region. At the time the picture was taken, remnants of seasonal frost remained on the crater rim and on the edges of the troughs that bound each of the polygons. Frost often provides a helpful hint as to where polygons and patterned ground occur. The polygons, if they were on Earth, would indicate the presence of freeze-thaw cycles in ground ice. Although uncertain, the same might be true of Mars. Sunlight illuminates the scene from the lower left.

  17. Sclerotherapy of Varicose Veins and Spider Veins

    ... Index A-Z Sclerotherapy of Varicose Veins and Spider Veins Sclerotherapy uses injections from a very fine, ... Sclerotherapy? What is Sclerotherapy of Varicose Veins and Spider Veins? Sclerotherapy is a minimally invasive treatment used ...

  18. Application of 3 kinds of practical electromagnetic spiders in electromagnetic spider web

    Jiang Min

    2016-01-01

    Electromagnetic spider web the launch circuit has introduced a lot, but in the center position of the utility of the spider generally have 3 kinds of circuits respectively, the use of single-chip microcomputer circuit of the low energy consumption spider by multi-channel transmission, single circuit receiver circuit. Direct use of the 3 channels of the spider and the use of PLC circuit spider, depending on the actual situation were placed.

  19. Application of 3 kinds of practical electromagnetic spiders in electromagnetic spider web

    Jiang Min

    2016-01-01

    Full Text Available Electromagnetic spider web the launch circuit has introduced a lot, but in the center position of the utility of the spider generally have 3 kinds of circuits respectively, the use of single-chip microcomputer circuit of the low energy consumption spider by multi-channel transmission, single circuit receiver circuit. Direct use of the 3 channels of the spider and the use of PLC circuit spider, depending on the actual situation were placed.

  20. Spider phylogenomics: untangling the Spider Tree of Life

    Nicole L. Garrison

    2016-02-01

    Full Text Available Spiders (Order Araneae are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the “usual suspect” genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125–90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results

  1. Spider phylogenomics: untangling the Spider Tree of Life

    Garrison, Nicole L.; Rodriguez, Juanita; Agnarsson, Ingi; Coddington, Jonathan A.; Griswold, Charles E.; Hamilton, Christopher A.; Hedin, Marshal; Kocot, Kevin M.; Ledford, Joel M.

    2016-01-01

    Spiders (Order Araneae) are massively abundant generalist arthropod predators that are found in nearly every ecosystem on the planet and have persisted for over 380 million years. Spiders have long served as evolutionary models for studying complex mating and web spinning behaviors, key innovation and adaptive radiation hypotheses, and have been inspiration for important theories like sexual selection by female choice. Unfortunately, past major attempts to reconstruct spider phylogeny typically employing the “usual suspect” genes have been unable to produce a well-supported phylogenetic framework for the entire order. To further resolve spider evolutionary relationships we have assembled a transcriptome-based data set comprising 70 ingroup spider taxa. Using maximum likelihood and shortcut coalescence-based approaches, we analyze eight data sets, the largest of which contains 3,398 gene regions and 696,652 amino acid sites forming the largest phylogenomic analysis of spider relationships produced to date. Contrary to long held beliefs that the orb web is the crowning achievement of spider evolution, ancestral state reconstructions of web type support a phylogenetically ancient origin of the orb web, and diversification analyses show that the mostly ground-dwelling, web-less RTA clade diversified faster than orb weavers. Consistent with molecular dating estimates we report herein, this may reflect a major increase in biomass of non-flying insects during the Cretaceous Terrestrial Revolution 125–90 million years ago favoring diversification of spiders that feed on cursorial rather than flying prey. Our results also have major implications for our understanding of spider systematics. Phylogenomic analyses corroborate several well-accepted high level groupings: Opisthothele, Mygalomorphae, Atypoidina, Avicularoidea, Theraphosoidina, Araneomorphae, Entelegynae, Araneoidea, the RTA clade, Dionycha and the Lycosoidea. Alternatively, our results challenge the

  2. An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design

    Rifai, Damhuji; Abdalla, Ahmed N.; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A.

    2017-01-01

    The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient. PMID:28335399

  3. Approach and avoidance in fear of spiders

    Rinck, M.; Becker, E.S.

    2007-01-01

    We examined attitudes towards spiders by employing an Approach-Avoidance Task, in which participants respond to pictures by pulling a joystick towards themselves or by pushing it away from themselves. For spider fearfuls, this stimulus–response assignment is either compatible (push spiders away) or

  4. Spider and burnable poison rod combinations

    Edwards, G.T.; Schluderberg, D.C.

    1980-01-01

    An improved design of burnable poison rods and associated spiders used in fuel assemblies of pressurized water power reactor cores, is described. The rods are joined to the spider arms in a manner which is proof against the reactor core environment and yet allows the removal of the rods from the spider simply, swiftly and delicately. (U.K.)

  5. Optimization of in situ prompt gamma-ray analysis using a HPGe-252Cf probe

    Chien Chung; Jiunnhsing Chao

    1991-01-01

    Application of in situ measurements by the neutron-induced prompt gamma-ray activation analysis (PGAA) technique to geochemical analysis and mineral survey have been investigated. An in situ survey of water pollutants by PGAA techniques was first proposed in the authors' previous study, where a 2.7-μg 252 Cf neutron source used in connection with a gamma-ray detecting system to determine water pollutants was described. In this paper the authors describe a modified detection probe designed and constructed to look for the optimum conditions of various-intensity 252 Cf neutron sources in measurement of some elements in lake water. Detecting efficiencies at high-energy regions and detection limits for elements commonly found in polluted lakes were evaluated and predicted to investigate the potential application of the probe for in situ measurements

  6. Molecular phylogeny of moth-specialized spider sub-family Cyrtarachninae, which includes bolas spiders.

    Tanikawa, Akio; Shinkai, Akira; Miyashita, Tadashi

    2014-11-01

    The evolutionary process of the unique web architectures of spiders of the sub-family Cyrtarachninae, which includes the triangular web weaver, bolas spider, and webless spider, is thought to be derived from reduction of orbicular 'spanning-thread webs' resembling ordinal orb webs. A molecular phylogenetic analysis was conducted to explore this hypothesis using orbicular web spiders Cyrtarachne, Paraplectana, Poecilopachys, triangular web spider Pasilobus, bolas spiders Ordgarius and Mastophora, and webless spider Celaenia. The phylogeny inferred from partial sequences of mt-COI, nuclear 18S-rRNA and 28S-rRNA showed that the common ancestor of these spiders diverged into two clades: a spanning-thread web clade and a bolas or webless clade. This finding suggests that the triangular web evolved by reduction of an orbicular spanning web, but that bolas spiders evolved in the early stage, which does not support the gradual web reduction hypothesis.

  7. Reconstitutable control rod spider assembly

    Shallenberger, J.M.; Ferian, S.J.

    1990-01-01

    A reconstitutable control rod/spider assembly includes a hollow connecting finger of the spider having a pair of opposing flat segments formed on the interior thereof and engaging a pair of opposing flat sectors formed on the exterior of a stem extending form the upper end of control rod. The stem also has an externally-threaded portion engaging a nut and a pilot aligning portion for the nut. The nut has a radially flexible and expandable thread-defining element captured in its bore. The segments and sectors allow the rod to be removed and reattached after turning through 180 0 to allow more even wear on the rod. (author)

  8. THE EXECUTION OF PLANNED DETOURS BY SPIDER-EATING PREDATORS

    Cross, Fiona R.; Jackson, Robert R.

    2016-01-01

    Many spiders from the salticid subfamily Spartaeinae specialize at preying on other spiders and they adopt complex strategies when targeting these dangerous prey. We tested 15 of these spider-eating spartaeine species for the capacity to plan detours ahead of time. Each trial began with the test subject on top of a tower from which it could view two boxes: one containing prey and the other not containing prey. The distance between the tower and the boxes was too far to reach by leaping and the tower sat on a platform surrounded by water. As the species studied are known to avoid water, the only way they could reach the prey without getting wet was by taking one of two circuitous walkways from the platform: one leading to the prey (‘correct’) and one not leading to the prey (‘incorrect’). After leaving the tower, the test subject could not see the prey and sometimes it had to walk past the incorrect walkway before reaching the correct walkway. Yet all 15 species chose the correct walkway significantly more often than the incorrect walkway. We propose that these findings exemplify genuine cognition based on representation. PMID:26781057

  9. The Spider and the Fly

    Mellinger, Keith E.; Viglione, Raymond

    2012-01-01

    The Spider and the Fly puzzle, originally attributed to the great puzzler Henry Ernest Dudeney, and now over 100 years old, asks for the shortest path between two points on a particular square prism. We explore a generalization, find that the original solution only holds in certain cases, and suggest how this discovery might be used in the…

  10. SkyProbeBV: dual-color absolute sky transparency monitor to optimize science operations

    Cuillandre, Jean-Charles; Magnier, Eugene; Sabin, Dan; Mahoney, Billy

    2008-07-01

    Mauna Kea (4200 m elevation, Hawaii) is known for its pristine seeing conditions, but sky transparency can be an issue for science operations: 25% of the nights are not photometric, a cloud coverage mostly due to high-altitude thin cirrus. The Canada-France-Hawaii Telescope (CFHT) is upgrading its real-time sky transparency monitor in the optical domain (V-band) into a dual-color system by adding a B-band channel and redesigning the entire optical and mechanical assembly. Since 2000, the original single-channel SkyProbe has gathered one exposure every minute during each observing night using a small CCD camera with a very wide field of view (35 sq. deg.) encompassing the region pointed by the telescope for science operations, and exposures long enough (30 seconds) to capture at least 100 stars of Hipparcos' Tychos catalog at high galactic latitudes (and up to 600 stars at low galactic latitudes). A key advantage of SkyProbe over direct thermal infrared imaging detection of clouds, is that it allows an accurate absolute measurement, within 5%, of the true atmospheric absorption by clouds affecting the data being gathered by the telescope's main science instrument. This system has proven crucial for decision making in the CFHT queued service observing (QSO), representing today 95% of the telescope time: science exposures taken in non-photometric conditions are automatically registered for being re-observed later on (at 1/10th of the original exposure time per pointing in the observed filters) to ensure a proper final absolute photometric calibration. If the absorption is too high, exposures can be repeated, or the observing can be done for a lower ranked science program. The new dual color system (simultaneous B & V bands) will allow a better characterization of the sky properties above Mauna Kea and should enable a better detection of the thinner cirrus (absorption down to 0.02 mag., i.e. 2%). SkyProbe is operated within the Elixir pipeline, a collection of tools

  11. Optimal design and fabrication of three-dimensional calibration specimens for scanning probe microscopy

    Liu Xiaoning; Luo Tingting; Chen Yuhang; Huang Wenhao [Department of Precision Machinery and Instrumentation, University of Science and Technology of China, 230026 Hefei (China); Piaszenski, Guido [Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund (Germany)

    2012-05-15

    Micro-/nano-scale roughness specimens are highly demanded to synthetically calibrate the scanning probe microscopy (SPM) instrument. In this study, three-dimensional (3D) specimens with controllable main surface evaluation parameters were designed. In order to improve the design accuracy, the genetic algorithm was introduced into the conventional digital filter method. A primary 3D calibration specimen with the dimension of 10 {mu}m x 10 {mu}m was fabricated by electron beam lithography. Atomic force microscopy characterizations demonstrated that the statistical and spectral parameters of the fabricated specimen match well with the designed values. Such a kind of 3D specimens has the potential to calibrate the SPM for applications in quantitative surface evaluations.

  12. Statistically optimized near field acoustic holography using an array of pressure-velocity probes

    Jacobsen, Finn; Jaud, Virginie

    2007-01-01

    of a measurement aperture that extends well beyond the source can be relaxed. Both NAH and SONAH are based on the assumption that all sources are on one side of the measurement plane whereas the other side is source free. An extension of the SONAH procedure based on measurement with a double layer array...... of pressure microphones has been suggested. The double layer technique makes it possible to distinguish between sources on the two sides of the array and thus suppress the influence of extraneous noise coming from the “wrong” side. It has also recently been demonstrated that there are significant advantages...... in NAH based on an array of acoustic particle velocity transducers (in a single layer) compared with NAH based on an array of pressure microphones. This investigation combines the two ideas and examines SONAH based on an array of pressure-velocity intensity probes through computer simulations as well...

  13. Optimized probes for dose rate measurements at local government sites and in emergency planning zones and their integration into measurement networks

    Kuca, Petr; Helebrant, Jan; Cespirova, Irena; Judas, Libor; Skala, Lukas

    2015-01-01

    The results of a security project aimed at the development of a radiation situation monitoring system using optimized probes for dose rate measurements are described. The system is suitable for use at local government sites as well as at other sites. The system includes dose rate measurement probes with the variable configuration functionality (detection part), equipment for data transfer to a central workplace (communication part) and application for collection, storage and administration of the results and their presentation at a website (presentation part). The dosimetric and other operational properties of the probes were tested and the feasibility of their integration into measurement networks using the IMS central application was examined. (orig.)

  14. Reverse line blot probe design and polymerase chain reaction optimization for bloodmeal analysis of ticks from the eastern United States.

    Scott, M C; Harmon, J R; Tsao, J I; Jones, C J; Hickling, G J

    2012-05-01

    Determining the host preference of vector ticks is vital to elucidating the eco-epidemiology of the diseases they spread. Detachment of ticks from captured hosts can provide evidence of feeding on those host species, but only for those species that are feasible to capture. Recently developed, highly sensitive molecular assays show great promise in allowing host selection to be determined from minute traces of host DNA that persist in recently molted ticks. Using methods developed in Europe as a starting-point, we designed 12S rDNA mitochondrial gene probes suitable for use in a reverse line blot (RLB) assay of ticks feeding on common host species in the eastern United States. This is the first study to use the 12S mitochondrial gene in a RLB bloodmeal assay in North America. The assay combines conventional PCR with a biotin-labeled primer and reverse line blots that can be stripped and rehybridized up to 20 times, making the method less expensive and more straightforward to interpret than previous methods of tick bloodmeal identification. Probes were designed that target the species, genus, genus group, family, order, or class of eight reptile, 13 birds, and 32 mammal hosts. After optimization, the RLB assay correctly identified the current hostspecies for 99% of ticks [Amblyomma americanum (L.) and eight other ixodid tick species] collected directly from known hosts. The method identified previous-host DNA for approximately half of all questing ticks assayed. Multiple bloodmeal determinations were obtained in some instances from feeding and questing ticks; this pattern is consistent with previous RLB studies but requires further investigation. Development of this probe library, suitable for eastern U.S. ecosystems, opens new avenues for eco-epidemiological investigations of this region's tick-host systems.

  15. Specialised use of working memory by Portia africana, a spider-eating salticid.

    Cross, Fiona R; Jackson, Robert R

    2014-03-01

    Using expectancy-violation methods, we investigated the role of working memory in the predatory strategy of Portia africana, a salticid spider from Kenya that preys by preference on other spiders. One of this predator's tactics is to launch opportunistic leaping attacks on to other spiders in their webs. Focussing on this particular tactic, our experiments began with a test spider on a ramp facing a lure (dead prey spider mounted on a cork disc) that could be reached by leaping. After the test spider faced the lure for 30 s, we blocked the test spider's view of the lure by lowering an opaque shutter before the spider leapt. When the shutter was raised 90 s later, either the same lure came into view again (control) or a different lure came into view (experimental: different prey type in same orientation or same prey type in different orientation). We recorded attack frequency (number of test spiders that leapt at the lure) and attack latency (time elapsing between shutter being raised and spiders initiating a leap). Attack latencies in control trials were not significantly different from attack latencies in experimental trials, regardless of whether it was prey type or prey orientation that changed in the experimental trials. However, compared with test spiders in the no-change control trials, significantly fewer test spiders leapt when prey type changed. There was no significant effect on attack frequency when prey orientation changed. These findings suggest that this predator represents prey type independently of prey orientation.

  16. The evolution of sociality in spiders

    Lubin, Yael; Bilde, T.

    2007-01-01

    . Anelosimus (Theridiidae) C. Sociality in Spiders: An Evolutionary Dead End? V. Evolution and Maintenance of Sociality in Spiders: Relevant Models A. Kin Selection 1. Kin Recognition 2. Inbreeding and Kin Selection B. Multilevel Selection (Group Selection) C. Ecological Benefits D. Ecological Constraints E......I. Introducing Social Spiders II. Social and Subsocial Species: A Survey of Behavioral Traits III. Inbred Sociality in Spiders A. Cooperation Versus Competition: A Balancing Act B. Do Social Spiders Have Division of Labor? C. Colony Foundation: Propagule Dispersal Versus Fission D. Female......-Biased Colony Sex Ratios: Primary and Operational Sex Ratios E. Mating System: Inbreeding and Its Population-Genetic Consequences F. "Boom and Bust" Colony Dynamics IV. Phylogenetic Relationships Among Social Spider Species A. Common Features of Social Evolution B. Case Studies 1. Stegodyphus (Eresidae) 2...

  17. Radiation effect onto biodiversity of spiders

    Mehrabova, M.A.; Naghiyev, J.A; Huseynov, N.I; Topchiyeva, Sh.A.; Hasanov, N.H.

    2010-01-01

    At present time spiders are one of the considerably diverse groups of living organisms in fauna of Azerbayjan Republic. They play an important in environmental chain, being the main group of wild arthropodas in most biocoenoses. Therefore, it's not surprised that recently an increased interest has being observed to the study of spiders as indicators of environmental conditions. Spiders have been collected in polluted areas, their identification and sampling of soil, water and plants has been conducted. The degree of radionuclides' impact on the number and distribution of spiders and their venom in the observed zones of Azerbaijan has been revealed and preliminarily predicted. The number of the collected spiders equals to 292 which has been determined later at an electronic identifier Spinnen Mitteleuropas. The radionuclides in spiders have been determined at Canberra facility. Different natural radioactive elements were revealed in the investigated samples.

  18. Design of the interlock and protection system for the SPIDER experiment

    Pomaro, N.; Grando, L.; Luchetta, A.; Paolucci, F.; Sartori, F.

    2013-01-01

    Highlights: •A custom designed interlock and protection system for SPIDER experiment is described. •It includes two subsystems implementing slow and fast protection functions. •High reliability PLCs are adopted for slow protection. •Fiber-optic based, custom designed fast logic circuitry is proposed for fast protection. •Accelerators breakdown events are also managed by the fast subsystem. -- Abstract: Unprecedented levels of beam energy and power are required for ITER Neutral Beam Heating systems. SPIDER experiment is an experimental device aimed to test and optimize a full size beam source satisfying ITER requirements. SPIDER experiment operation involves high power, voltage, temperature, and gas pressure. All these critical conditions are present simultaneously, so that any failure if not properly detected and managed is likely to cause severe damage. The Interlock and Protection System is a high-reliability system devoted to the investment protection of SPIDER. Its main purpose is to manage abnormal events occurring in one or more plants in order to minimize adverse consequences. The Interlock System also manages the SPIDER Operating Modes, defining the set and status of the Plants used in the various possible experimental configurations. In addition, the Interlock and Protection System takes care of particular events occurring during normal SPIDER operation, i.e. electrical arcs between accelerator grids, named breakdowns. Their treatment is committed to the Interlock and Protection System, as they need to be managed timely and with absolute reliability like actual faults. To perform the required functions, the Interlock and Protection System is interfaced with most SPIDER plants and with the SPIDER Control and Data Acquisition System. The paper describes the rationale of the protection functions, their implementation in the design and the technical specifications of the system

  19. Development and validation of a numerical model for cross-section optimization of a multi-part probe for soft tissue intervention.

    Frasson, L; Neubert, J; Reina, S; Oldfield, M; Davies, B L; Rodriguez Y Baena, F

    2010-01-01

    The popularity of minimally invasive surgical procedures is driving the development of novel, safer and more accurate surgical tools. In this context a multi-part probe for soft tissue surgery is being developed in the Mechatronics in Medicine Laboratory at Imperial College, London. This study reports an optimization procedure using finite element methods, for the identification of an interlock geometry able to limit the separation of the segments composing the multi-part probe. An optimal geometry was obtained and the corresponding three-dimensional finite element model validated experimentally. Simulation results are shown to be consistent with the physical experiments. The outcome of this study is an important step in the provision of a novel miniature steerable probe for surgery.

  20. Science Education Resources on the Web--Spiders.

    Thirunarayanan, M. O.

    1997-01-01

    Lists Web sites containing information on spiders and offers brief descriptions of the information available at those sites. The 11 sites provide information on taxonomy of spiders, anatomy, different ways spiders use silk, Internet mailing lists, folk literature and art, bibliographies, night collection, and spiders commonly found in the state of…

  1. Tangled in a sparse spider web

    Dimitrov, Dimitar Stefanov; Lopardo, Lara; Giribet, Gonzalo

    2012-01-01

    In order to study the tempo and the mode of spider orb web evolution and diversification, we conducted a phylogenetic analysis using six genetic markers along with a comprehensive taxon sample. The present analyses are the first to recover the monophyly of orb-weaving spiders based solely on DNA ...

  2. Attention bias modification in specific fears: Spiders versus snakes.

    Luo, Xijia; Ikani, Nessa; Barth, Anja; Rengers, Lea; Becker, Eni; Rinck, Mike

    2015-12-01

    Attention Bias Modification (ABM) is used to manipulate attention biases in anxiety disorders. It has been successful in reducing attention biases and anxious symptoms in social anxiety and generalized anxiety, but not yet in specific fears and phobias. We designed a new version of the dot-probe training task, aiming to train fearful participants' attention away from or towards pictures of threatening stimuli. Moreover, we studied whether the training also affected participants' avoidance behavior and their physical arousal upon being confronted with a real threat object. In Experiment 1, students with fear of spiders were trained. We found that the attention manipulation was successful, but the training failed to affect behavior or arousal. In Experiment 2, the same procedure was used on snake-fearful students. Again, attention was trained in the expected directions. Moreover, participants whose attention had been trained away from snakes showed lower physiological arousal upon being confronted with a real snake. The study involved healthy students with normal distribution of the fear of spider/snake. Future research with clinical sample could help with determining the generalizability of the current findings. The effect of ABM on specific phobia is still in question. The finding in the present study suggested the possibility to alter attentional bias with a dot-probe task with general positive stimuli and this training could even affect the behavior while encountering a real threat. Copyright © 2015 Elsevier Ltd. All rights reserved.

  3. Verified spider bites in Oregon (USA) with the intent to assess hobo spider venom toxicity.

    McKeown, Nathanael; Vetter, Richard S; Hendrickson, Robert G

    2014-06-01

    This study compiled 33 verified spider bites from the state of Oregon (USA). The initial goal was to amass a series of bites by the hobo spider to assess whether it possesses toxic venom, a supposition which is currently in a contested state. None of the 33 bites from several spider species developed significant medical symptoms nor did dermonecrosis occur. The most common biters were the yellow sac spider, Cheiracanthium mildei (N = 10) and orb-weavers of the genus Araneus (N = 6). There were 10 bites from three genera of funnel web spiders of the family Agelenidae including one hobo spider bite and one from the congeneric giant house spider which is readily confused as a hobo spider. The hobo spider bite resulted in pain, redness, twitching in the calf muscle and resolved in 12 h. Also generated from this study were possibly the first records of bites from spiders of the genera Callobius (Amaurobiidae) and Antrodiaetus (Antrodiaetidae), both with minor manifestations. Published by Elsevier Ltd.

  4. Spider Silk Violin Strings with a Unique Packing Structure Generate a Soft and Profound Timbre

    Osaki, Shigeyoshi

    2012-04-01

    We overcome the difficulties in pulling long draglines from spiders, twist bundles of dragline filaments, and succeed in preparing violin strings. The twisting is found to change the cross section shapes of filaments from circular to polygonal and to optimize the packing structure with no openings among filaments providing mechanically strong and elastic strings. The spider string signal peaks of overtones for the violin are relatively large at high frequencies, generating a soft and profound timbre. Such a preferable timbre is considered to be due to the unique polygonal packing structure which provides valuable knowledge for developing new types of materials.

  5. Numerical simulations of the first operational conditions of the negative ion test facility SPIDER

    Serianni, G.; Agostinetti, P.; Antoni, V.; Baltador, C.; Chitarin, G.; Marconato, N.; Pasqualotto, R.; Sartori, E.; Toigo, V.; Veltri, P.; Cavenago, M.

    2016-01-01

    In view of the realization of the negative ion beam injectors for ITER, a test facility, named SPIDER, is under construction in Padova (Italy) to study and optimize production and extraction of negative ions. The present paper is devoted to the analysis of the expected first operations of SPIDER in terms of single-beamlet and multiple-beamlet simulations of the hydrogen beam optics in various operational conditions. The effectiveness of the methods adopted to compensate for the magnetic deflection of the particles is also assessed. Indications for a sequence of the experimental activities are obtained

  6. Multivariate ordination identifies vegetation types associated with spider conservation in brassica crops

    Hafiz Sohaib Ahmed Saqib

    2017-10-01

    Full Text Available Conservation biological control emphasizes natural and other non-crop vegetation as a source of natural enemies to focal crops. There is an unmet need for better methods to identify the types of vegetation that are optimal to support specific natural enemies that may colonize the crops. Here we explore the commonality of the spider assemblage—considering abundance and diversity (H—in brassica crops with that of adjacent non-crop and non-brassica crop vegetation. We employ spatial-based multivariate ordination approaches, hierarchical clustering and spatial eigenvector analysis. The small-scale mixed cropping and high disturbance frequency of southern Chinese vegetation farming offered a setting to test the role of alternate vegetation for spider conservation. Our findings indicate that spider families differ markedly in occurrence with respect to vegetation type. Grassy field margins, non-crop vegetation, taro and sweetpotato harbour spider morphospecies and functional groups that are also present in brassica crops. In contrast, pumpkin and litchi contain spiders not found in brassicas, and so may have little benefit for conservation biological control services for brassicas. Our findings also illustrate the utility of advanced statistical approaches for identifying spatial relationships between natural enemies and the land uses most likely to offer alternative habitats for conservation biological control efforts that generates testable hypotheses for future studies.

  7. Maternal care and subsocial behaviour in spiders.

    Yip, Eric C; Rayor, Linda S

    2014-05-01

    While most spiders are solitary and opportunistically cannibalistic, a variety of social organisations has evolved in a minority of spider species. One form of social organisation is subsociality, in which siblings remain together with their parent for some period of time but disperse prior to independent reproduction. We review the literature on subsocial and maternal behaviour in spiders to highlight areas in which subsocial spiders have informed our understanding of social evolution and to identify promising areas of future research. We show that subsocial behaviour has evolved independently at least 18 times in spiders, across a wide phylogenetic distribution. Subsocial behaviour is diverse in terms of the form of care provided by the mother, the duration of care and sibling association, the degree of interaction and cooperation among siblings, and the use of vibratory and chemical communication. Subsocial spiders are useful model organisms to study various topics in ecology, such as kin recognition and the evolution of cheating and its impact on societies. Further, why social behaviour evolved in some lineages and not others is currently a topic of debate in behavioural ecology, and we argue that spiders offer an opportunity to untangle the ecological causes of parental care, which forms the basis of many other animal societies. © 2013 The Authors. Biological Reviews © 2013 Cambridge Philosophical Society.

  8. Understanding Spider-Man: Your Everyday Superhero

    Falk, Nicklas; Blomsterberg, Sofie Amalie; Suciu, Alice Sabrina; Pedersen, Mads Peter; Lucas, Vilhelm

    2014-01-01

    This project focuses on the understanding of Spider-Man, and the morals and ethics that lie behind the choices he makes. Through the Dimensions Philosophy & Science/Text & Sign, this understanding is concluded by looking at ethical theories and comic book analysis. Based on the Ultimate Spider-Man comic book series, the aim is to clarify who Spider-Man is and what causes him to act in certain ways; before and after his realization of power. Some theories used to investigate these area...

  9. Synthetic spider silk sustainability verification by techno-economic and life cycle analysis

    Edlund, Alan

    Major ampullate spider silk represents a promising biomaterial with diverse commercial potential ranging from textiles to medical devices due to the excellent physical and thermal properties from the protein structure. Recent advancements in synthetic biology have facilitated the development of recombinant spider silk proteins from Escherichia coli (E. coli), alfalfa, and goats. This study specifically investigates the economic feasibility and environmental impact of synthetic spider silk manufacturing. Pilot scale data was used to validate an engineering process model that includes all of the required sub-processing steps for synthetic fiber manufacture: production, harvesting, purification, drying, and spinning. Modeling was constructed modularly to support assessment of alternative protein production methods (alfalfa and goats) as well as alternative down-stream processing technologies. The techno-economic analysis indicates a minimum sale price from pioneer and optimized E. coli plants at 761 kg-1 and 23 kg-1 with greenhouse gas emissions of 572 kg CO2-eq. kg-1 and 55 kg CO2-eq. kg-1, respectively. Spider silk sale price estimates from goat pioneer and optimized results are 730 kg-1 and 54 kg-1, respectively, with pioneer and optimized alfalfa plants are 207 kg-1 and 9.22 kg-1 respectively. Elevated costs and emissions from the pioneer plant can be directly tied to the high material consumption and low protein yield. Decreased production costs associated with the optimized plants include improved protein yield, process optimization, and an Nth plant assumption. Discussion focuses on the commercial potential of spider silk, the production performance requirements for commercialization, and impact of alternative technologies on the sustainability of the system.

  10. Dimensioning of optimal probe circuits for the non-destructive testing of materials by eddy-current using Buschbeck-Meinke chart

    Ott, A.

    1982-01-01

    By application of a modified form of the Buschbeck-Meinke-diagram, known from conduction theory, easy-to use dimensioning rules can be given for the probe circuits of single-frequency eddy-current test instruments. Dimensioning is found for circuits that work with amplitude or phase measurements, that suppress optimal the disturbance parameters in certain regions. In a similar way one can determine dimensioning, with which the measurement quantity causes the highest possible signal charge. (orig.) [de

  11. Efficient Journaling for the Spider Storage System

    Oral, H Sarp [ORNL; Wang, Feiyi [ORNL; Shipman, Galen M [ORNL; Dillow, David A [ORNL; Miller, Ross G [ORNL; Drokin, Oleg [ORNL

    2003-01-01

    Journaling is a widely used technique to increase file system robustness against meta data and/or data corruptions. While the overhead of journaling can be negligible for small-scale file systems, we found that two aspects of local back-end file system journaling significantly lower the overall performance of a large-scale parallel file system such as Lustre: extra head seeks and serialization of incoming client requests. Journal transactions reside on a separate area of the disk that the file data, and each commit of the journal requires a head seek. Incoming client requests become serialized and take a latency hit by waiting for a commit to occur before the reply is sent. In this paper we present two different approaches to increase the local back-end file system journaling efficiency, thus increasing the overall aggregate parallel file system efficiency. First, we present a hardware-based solution where a solid-state device is used as an external journaling device to minimize the disk head seek. Second, we introduce a software-based optimization to allow asynchronously commit multiple journal transactions on the local back-end file system to minimize the penalty of serialization. Both our solutions are experimentally tested on Oak Ridge National Laboratory's large-scale Spider storage system and our tests show that both methods nearly double the overall parallel write performance.

  12. Non-webbuilding spiders: prey specialists or generalists?

    Nentwig, Wolfgang

    1986-07-01

    Feeding experiments were performed with seven species of non-webbuilding spiders and a variety of prey taxa. Some species were generally polyphagous whereas other spiders restricted their prey to a few groups. At one end of the spectrum of prey specialization the thomisid Misumena vatia is limited to a few taxa of possible prey (Table 1). The literature of prey records of non-webbuilding spiders is reviewed (Table 2) with special emphasis on oligophagous or monophagous spiders. Monophagous spiders are generally rare and have specialized on only a few prey taxa: social insects (ants, bees, termites) and spiders.

  13. Almost a spider: a 305-million-year-old fossil arachnid and spider origins.

    Garwood, Russell J; Dunlop, Jason A; Selden, Paul A; Spencer, Alan R T; Atwood, Robert C; Vo, Nghia T; Drakopoulos, Michael

    2016-03-30

    Spiders are an important animal group, with a long history. Details of their origins remain limited, with little knowledge of their stem group, and no insights into the sequence of character acquisition during spider evolution. We describe a new fossil arachnid, Idmonarachne brasierigen. et sp. nov. from the Late Carboniferous (Stephanian,ca 305-299 Ma) of Montceau-les-Mines, France. It is three-dimensionally preserved within a siderite concretion, allowing both laboratory- and synchrotron-based phase-contrast computed tomography reconstruction. The latter is a first for siderite-hosted fossils and has allowed us to investigate fine anatomical details. Although distinctly spider-like in habitus, this remarkable fossil lacks a key diagnostic character of Araneae: spinnerets on the underside of the opisthosoma. It also lacks a flagelliform telson found in the recently recognized, spider-related, Devonian-Permian Uraraneida. Cladistic analysis resolves our new fossil as sister group to the spiders: the spider stem-group comprises the uraraneids and I. brasieri While we are unable to demonstrate the presence of spigots in this fossil, the recovered phylogeny suggests the earliest character to evolve on the spider stem-group is the secretion of silk. This would have been followed by the loss of a flagelliform telson, and then the ability to spin silk using spinnerets. This last innovation defines the true spiders, significantly post-dates the origins of silk, and may be a key to the group's success. The Montceau-les-Mines locality has previously yielded a mesothele spider (with spinnerets). Evidently, Late Palaeozoic spiders lived alongside Palaeozoic arachnid grades which approached the spider condition, but did not express the full suite of crown-group autapomorphies. © 2016 The Authors.

  14. Edge effect on weevils and spiders

    Horváth, R.; Magura, T.; Péter, G.; Tóthmérész, B.

    2002-01-01

    The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest...

  15. Spiders do have melanin after all.

    Hsiung, Bor-Kai; Blackledge, Todd A; Shawkey, Matthew D

    2015-11-01

    Melanin pigments are broadly distributed in nature - from bacteria to fungi to plants and animals. However, many previous attempts to identify melanins in spiders were unsuccessful, suggesting that these otherwise ubiquitous pigments were lost during spider evolution. Yet, spiders exhibit many dark colours similar to those produced by melanins in other organisms, and the low solubility of melanins makes isolation and characterization difficult. Therefore, whether melanins are truly absent or have simply not yet been detected is an open question. Raman spectroscopy provides a reliable way to detect melanins in situ, without the need for isolation. In this study, we document the presence of eumelanin in diverse species of spiders using confocal Raman microspectroscopy. Comparisons of spectra with theoretically calculated data falsify the previous hypothesis that dark colours are produced solely by ommochromes in spiders. Our data indicate that melanins are present in spiders and further supporting that they are present in most living organisms. © 2015. Published by The Company of Biologists Ltd.

  16. Genus-specificity of araneophagy of linyphiid spiders and spiders of other families (Arachnida, Araneae)

    Heuts, B.; Brunt, T.

    2009-01-01

    We found genus specificity of predation by spiders on other spiders in captivity which surpass them in body size (araneophagy). Adult specimens of three species of the linyphiid genus Walckenaeria which were successively tested for araneophagy (in the laboratory) in the order of first species

  17. Ant mimicry lessens predation on a North American jumping spider by larger salticid spiders.

    Durkee, Caitlin A; Weiss, Martha R; Uma, Divya B

    2011-10-01

    Ant-like appearance (myrmecomorphy) has evolved >70 times in insects and spiders, accounting for >2,000 species of myrmecomorphic arthropods. Most myrmecomorphic spiders are considered to be Batesian mimics; that is, a palatable spider avoids predation through resemblance to an unpalatable ant-although this presumption has been tested in relatively few cases. Here we explicitly examined the extent to which Peckhamia picata (Salticidae), a North American ant-mimicking jumping spider, is protected from four species of jumping spider predators, relative to nonmimetic salticids and model ants. In addition, we conducted focused behavioral observations on one salticid predator, Thiodina puerpera, to determine the point at which the predators' behaviors toward model, mimic, and nonmimic diverge. We also examined the behaviors of Peckhamia in the presence of Thiodina. We found that mimetic jumping spiders were consumed less than a third as often as nonmimetic jumping spiders, suggesting that Peckhamia does indeed gain protection as a result of its resemblance to ants, and so can be considered a Batesian mimic. Furthermore, our focal predator did not consume any ant-mimicking spiders, and seemed to categorize Peckhamia with its model ant early in the hunting sequence. Such early determination of prey versus nonprey may be the result of speed-accuracy trade-offs in predator decision-making.

  18. Cognitive bias in spider-phobic children: Comparison of a pictorial and a linguistic spider Stroop.

    Kindt, M.; Brosschot, J.F.

    1999-01-01

    Examined the relation between spider fear in children and cognitive processing bias toward threatening information. It was investigated whether spider fear in children is related to a cognitive bias for threatening pictures and words. Pictorial and linguistic Stroop stimuli were administered to 28

  19. An Optimized Set of Fluorescence In Situ Hybridization Probes for Detection of Pancreatobiliary Tract Cancer in Cytology Brush Samples.

    Barr Fritcher, Emily G; Voss, Jesse S; Brankley, Shannon M; Campion, Michael B; Jenkins, Sarah M; Keeney, Matthew E; Henry, Michael R; Kerr, Sarah M; Chaiteerakij, Roongruedee; Pestova, Ekaterina V; Clayton, Amy C; Zhang, Jun; Roberts, Lewis R; Gores, Gregory J; Halling, Kevin C; Kipp, Benjamin R

    2015-12-01

    Pancreatobiliary cancer is detected by fluorescence in situ hybridization (FISH) of pancreatobiliary brush samples with UroVysion probes, originally designed to detect bladder cancer. We designed a set of new probes to detect pancreatobiliary cancer and compared its performance with that of UroVysion and routine cytology analysis. We tested a set of FISH probes on tumor tissues (cholangiocarcinoma or pancreatic carcinoma) and non-tumor tissues from 29 patients. We identified 4 probes that had high specificity for tumor vs non-tumor tissues; we called this set of probes pancreatobiliary FISH. We performed a retrospective analysis of brush samples from 272 patients who underwent endoscopic retrograde cholangiopancreatography for evaluation of malignancy at the Mayo Clinic; results were available from routine cytology and FISH with UroVysion probes. Archived residual specimens were retrieved and used to evaluate the pancreatobiliary FISH probes. Cutoff values for FISH with the pancreatobiliary probes were determined using 89 samples and validated in the remaining 183 samples. Clinical and pathologic evidence of malignancy in the pancreatobiliary tract within 2 years of brush sample collection was used as the standard; samples from patients without malignancies were used as negative controls. The validation cohort included 85 patients with malignancies (46.4%) and 114 patients with primary sclerosing cholangitis (62.3%). Samples containing cells above the cutoff for polysomy (copy number gain of ≥2 probes) were classified as positive in FISH with the UroVysion and pancreatobiliary probes. Multivariable logistic regression was used to estimate associations between clinical and pathology findings and results from FISH. The combination of FISH probes 1q21, 7p12, 8q24, and 9p21 identified cancer cells with 93% sensitivity and 100% specificity in pancreatobiliary tissue samples and were therefore included in the pancreatobiliary probe set. In the validation cohort of

  20. Theory of NMR probe design

    Schnall, M.D.

    1988-01-01

    The NMR probe is the intrinsic part of the NMR system which allows transmission of a stimulus to a sample and the reception of a resulting signal from a sample. NMR probes are used in both imaging and spectroscopy. Optimal probe design is important to the production of adequate signal/moise. It is important for anyone using NMR techniques to understand how NMR probes work and how to optimize probe design

  1. Stochastic prey arrivals and crab spider giving-up times: simulations of spider performance using two simple "rules of thumb".

    Kareiva, Peter; Morse, Douglass H; Eccleston, Jill

    1989-03-01

    We compared the patch-choice performances of an ambush predator, the crab spider Misumena vatia (Thomisidae) hunting on common milkweed Asclepias syriaca (Asclepiadaceae) umbles, with two stochastic rule-of-thumb simulation models: one that employed a threshold giving-up time and one that assumed a fixed probability of moving. Adult female Misumena were placed on milkweed plants with three umbels, each with markedly different numbers of flower-seeking prey. Using a variety of visitation regimes derived from observed visitation patterns of insect prey, we found that decreases in among-umbel variance in visitation rates or increases in overall mean visitation rates reduced the "clarity of the optimum" (the difference in the yield obtained as foraging behavior changes), both locally and globally. Yield profiles from both models were extremely flat or jagged over a wide range of prey visitation regimes; thus, differences between optimal and "next-best" strategies differed only modestly over large parts of the "foraging landscape". Although optimal yields from fixed probability simulations were one-third to one-half those obtained from threshold simulations, spiders appear to depart umbels in accordance with the fixed probability rule.

  2. Energetics, scaling and sexual size dimorphism of spiders.

    Grossi, B; Canals, M

    2015-03-01

    The extreme sexual size dimorphism in spiders has motivated studies for many years. In many species the male can be very small relative to the female. There are several hypotheses trying to explain this fact, most of them emphasizing the role of energy in determining spider size. The aim of this paper is to review the role of energy in sexual size dimorphism of spiders, even for those spiders that do not necessarily live in high foliage, using physical and allometric principles. Here we propose that the cost of transport or equivalently energy expenditure and the speed are traits under selection pressure in male spiders, favoring those of smaller size to reduce travel costs. The morphology of the spiders responds to these selective forces depending upon the lifestyle of the spiders. Climbing and bridging spiders must overcome the force of gravity. If bridging allows faster dispersal, small males would have a selective advantage by enjoying more mating opportunities. In wandering spiders with low population density and as a consequence few male-male interactions, high speed and low energy expenditure or cost of transport should be favored by natural selection. Pendulum mechanics show the advantages of long legs in spiders and their relationship with high speed, even in climbing and bridging spiders. Thus small size, compensated by long legs should be the expected morphology for a fast and mobile male spider.

  3. Spider diffraction: a comparison of curved and straight legs

    Richter, J.L.

    1984-01-01

    It has been known for some time that, if curved legs rather than the usual straight ones are used in the spider that supports the secondary optics in certain telescopes, the visible diffraction effect is reduced. Fraunhofer theory is used to calculate the diffraction effects due to the curved leg spider. Calculated and photographic diffraction patterns are compared for straight and curved leg spiders

  4. Acute Generalized Exanthematous Pustulosis (AGEP Triggered by a Spider Bite

    Michael Makris

    2009-01-01

    Discussion: A spider bite may represent a possible causative factor of AGEP. A spider's venom contains sphingomyelinase that stimulates the release of IL8 and GM-CSF, which are involved in AGEP pathogenesis. Whether or not the con-current use of antibiotics has an effect in AGEP appearance when combined with a spider's venom, cannot be excluded.

  5. Remembering the object you fear: brain potentials during recognition of spiders in spider-fearful individuals.

    Michalowski, Jaroslaw M; Weymar, Mathias; Hamm, Alfons O

    2014-01-01

    In the present study we investigated long-term memory for unpleasant, neutral and spider pictures in 15 spider-fearful and 15 non-fearful control individuals using behavioral and electrophysiological measures. During the initial (incidental) encoding, pictures were passively viewed in three separate blocks and were subsequently rated for valence and arousal. A recognition memory task was performed one week later in which old and new unpleasant, neutral and spider pictures were presented. Replicating previous results, we found enhanced memory performance and higher confidence ratings for unpleasant when compared to neutral materials in both animal fearful individuals and controls. When compared to controls high animal fearful individuals also showed a tendency towards better memory accuracy and significantly higher confidence during recognition of spider pictures, suggesting that memory of objects prompting specific fear is also facilitated in fearful individuals. In line, spider-fearful but not control participants responded with larger ERP positivity for correctly recognized old when compared to correctly rejected new spider pictures, thus showing the same effects in the neural signature of emotional memory for feared objects that were already discovered for other emotional materials. The increased fear memory for phobic materials observed in the present study in spider-fearful individuals might result in an enhanced fear response and reinforce negative beliefs aggravating anxiety symptomatology and hindering recovery.

  6. Optimizing the fabrication of aluminum-coated fiber probes and their application to optical near-field lithography

    Madsen, S; Holme, NCR; Ramanujam, PS

    1998-01-01

    in terms of roughness and the presence of leaking holes in the coating. We report on how the quality of the coating depends on parameters such as deposition rate and background pressure during evaporation. We have used aluminum-coated fiber probes in lithographical studies of different materials, like side...

  7. Flee or fight: ontogenetic changes in the behavior of cobweb spiders in encounters with spider-hunting wasps.

    Uma, Divya B; Weiss, Martha R

    2012-12-01

    An animal's body size plays a predominant role in shaping its interspecific interactions, and, in encounters between two predators, often determines which shall be predator and which shall be prey. Spiders are top predators of insects, yet can fall prey to mud-dauber wasps that provision their larval nests with paralyzed spiders. Here we examined predator-prey interactions between Chalybion californicum (Saussure) (Sphecidae), a mud-dauber wasp, and Parasteatoda tepidariorum C. L. Koch (Theridiidae), a cobweb spider. We examined whether a spider's size influences its response to an attacking wasp, and report a size-dependent change in spider behavior: small-sized spiders fled, whereas medium- and large-sized spiders fought in response to wasp attacks. From the wasps' perspective, we examined whether spider size influences a wasp's hunting behavior and capture success. We found that wasps commonly approached small spiders, but were much less likely to approach medium and large spiders. However, wasp capture success did not vary with spider size. We also report a strategy used by Chalybion wasps toward cobweb spiders that is consistent with an interpretation of aggressive mimicry.

  8. Fish predation by semi-aquatic spiders: a global pattern.

    Martin Nyffeler

    Full Text Available More than 80 incidences of fish predation by semi-aquatic spiders--observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens--are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2-6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil. Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae, in two species of the superfamily Ctenoidea (family Ctenidae, and in one species of the superfamily Corinnoidea (family Liocranidae. The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences. There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the 'swimming' huntsman spider Heteropoda natans [Sparassidae] predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders' body length (the captured fish being, on average, 2.2 times as long as the spiders. Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance.

  9. Fish predation by semi-aquatic spiders: a global pattern.

    Nyffeler, Martin; Pusey, Bradley J

    2014-01-01

    More than 80 incidences of fish predation by semi-aquatic spiders--observed at the fringes of shallow freshwater streams, rivers, lakes, ponds, swamps, and fens--are reviewed. We provide evidence that fish predation by semi-aquatic spiders is geographically widespread, occurring on all continents except Antarctica. Fish predation by spiders appears to be more common in warmer areas between 40° S and 40° N. The fish captured by spiders, usually ranging from 2-6 cm in length, are among the most common fish taxa occurring in their respective geographic area (e.g., mosquitofish [Gambusia spp.] in the southeastern USA, fish of the order Characiformes in the Neotropics, killifish [Aphyosemion spp.] in Central and West Africa, as well as Australian native fish of the genera Galaxias, Melanotaenia, and Pseudomugil). Naturally occurring fish predation has been witnessed in more than a dozen spider species from the superfamily Lycosoidea (families Pisauridae, Trechaleidae, and Lycosidae), in two species of the superfamily Ctenoidea (family Ctenidae), and in one species of the superfamily Corinnoidea (family Liocranidae). The majority of reports on fish predation by spiders referred to pisaurid spiders of the genera Dolomedes and Nilus (>75% of observed incidences). There is laboratory evidence that spiders from several more families (e.g., the water spider Argyroneta aquatica [Cybaeidae], the intertidal spider Desis marina [Desidae], and the 'swimming' huntsman spider Heteropoda natans [Sparassidae]) predate fish as well. Our finding of such a large diversity of spider families being engaged in fish predation is novel. Semi-aquatic spiders captured fish whose body length exceeded the spiders' body length (the captured fish being, on average, 2.2 times as long as the spiders). Evidence suggests that fish prey might be an occasional prey item of substantial nutritional importance.

  10. Inbreeding avoidance in spiders: evidence for rescue effect in fecundity of female spiders with outbreeding opportunity

    Bilde, T.; Maklakov, A.A.; Schilling, Nadia

    2007-01-01

    avoidance can be because of low risk of inbreeding, variation in tolerance to inbreeding or high costs of outbreeding. We examined the relationship between inbreeding depression and inbreeding avoidance adaptations under two levels of inbreeding in the spider Oedothorax apicatus, asking whether preference...... for unrelated sperm via pre- and/or post-copulatory mechanisms could restore female fitness when inbreeding depression increases. Using inbred isofemale lines we provided female spiders with one or two male spiders of different relatedness in five combinations: one male sib; one male nonsib; two male sibs; two...

  11. SPIDER: A Framework for Understanding Driver Distraction.

    Strayer, David L; Fisher, Donald L

    2016-02-01

    The objective was to identify key cognitive processes that are impaired when drivers divert attention from driving. Driver distraction is increasingly recognized as a significant source of injuries and fatalities on the roadway. A "SPIDER" model is developed that identifies key cognitive processes that are impaired when drivers divert attention from driving. SPIDER is an acronym standing for scanning, predicting, identifying, decision making, and executing a response. When drivers engage in secondary activities unrelated to the task of driving, SPIDER-related processes are impaired, situation awareness is degraded, and the ability to safely operate a motor vehicle may be compromised. The pattern of interference helps to illuminate the sources of driver distraction and may help guide the integration of new technology into the automobile. © 2015, Human Factors and Ergonomics Society.

  12. Edge effect on weevils and spiders

    R. Horváth

    2002-05-01

    Full Text Available The edge effect on weevils and spiders was tested along oak forest – meadow transects using sweep-net samples at the Síkfökút Project in Hungary. For spiders the species richness was significantly higher in the forest edge than either in the meadow or the forest interior. For weevils the species richness of the forest edge was higher than that of the meadow, but the difference was not statistically significant whereas the species richness of the forest interior was significantly lower than that of the forest edge and the meadow. The composition of the spider assemblage of the edge was more similar to the forest, while the composition of weevils in the edge was more similar to the meadow. Our results based on two invertebrate groups operating on different trophic levels suggest that there is a significant edge effect for the studied taxa resulting in higher species richness in the edge.

  13. Aquatic subsidies transport anthropogenic nitrogen to riparian spiders

    Akamatsu, Fumikazu, E-mail: f-akamt55@pwri.go.jp [Department of Environmental Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan); Toda, Hideshige [Department of Environmental Sciences, Shinshu University, 3-1-1 Asahi, Matsumoto, Nagano 390-8621 (Japan)

    2011-05-15

    Stable nitrogen isotopic composition ({delta}{sup 15}N) of aquatic biota increases with anthropogenic N inputs such as sewage and livestock waste downstream. Increase in {delta}{sup 15}N of riparian spiders downstream may reflect the anthropogenic pollution exposure through predation on aquatic insects. A two-source mixing model based on stable carbon isotopic composition showed the greatest dependence on aquatic insects (84%) by horizontal web-building spiders, followed by intermediate (48%) and low (31%) dependence by cursorial and vertical web-building spiders, respectively. The spider body size was negatively correlated with the dietary proportion of aquatic insects and spider {delta}{sup 15}N. The aquatic subsidies transported anthropogenic N to smaller riparian spiders downstream. This transport of anthropogenic N was regulated by spider's guild designation and body size. - Highlights: > {delta}{sup 15}N of aquatic insects increases downstream with anthropogenic nitrogen inputs. > {delta}{sup 15}N of riparian spiders increases with a high dietary proportion of aquatic insects and smaller spider body size. > The aquatic subsidies transport anthropogenic nitrogen to smaller riparian spiders downstream. - Smaller spiders assimilate anthropogenic nitrogen through the predation on aquatic subsides.

  14. Aquatic subsidies transport anthropogenic nitrogen to riparian spiders

    Akamatsu, Fumikazu; Toda, Hideshige

    2011-01-01

    Stable nitrogen isotopic composition (δ 15 N) of aquatic biota increases with anthropogenic N inputs such as sewage and livestock waste downstream. Increase in δ 15 N of riparian spiders downstream may reflect the anthropogenic pollution exposure through predation on aquatic insects. A two-source mixing model based on stable carbon isotopic composition showed the greatest dependence on aquatic insects (84%) by horizontal web-building spiders, followed by intermediate (48%) and low (31%) dependence by cursorial and vertical web-building spiders, respectively. The spider body size was negatively correlated with the dietary proportion of aquatic insects and spider δ 15 N. The aquatic subsidies transported anthropogenic N to smaller riparian spiders downstream. This transport of anthropogenic N was regulated by spider's guild designation and body size. - Highlights: → δ 15 N of aquatic insects increases downstream with anthropogenic nitrogen inputs. → δ 15 N of riparian spiders increases with a high dietary proportion of aquatic insects and smaller spider body size. → The aquatic subsidies transport anthropogenic nitrogen to smaller riparian spiders downstream. - Smaller spiders assimilate anthropogenic nitrogen through the predation on aquatic subsides.

  15. Disentangling the phylogenetic and ecological components of spider phenotypic variation.

    Gonçalves-Souza, Thiago; Diniz-Filho, José Alexandre Felizola; Romero, Gustavo Quevedo

    2014-01-01

    An understanding of how the degree of phylogenetic relatedness influences the ecological similarity among species is crucial to inferring the mechanisms governing the assembly of communities. We evaluated the relative importance of spider phylogenetic relationships and ecological niche (plant morphological variables) to the variation in spider body size and shape by comparing spiders at different scales: (i) between bromeliads and dicot plants (i.e., habitat scale) and (ii) among bromeliads with distinct architectural features (i.e., microhabitat scale). We partitioned the interspecific variation in body size and shape into phylogenetic (that express trait values as expected by phylogenetic relationships among species) and ecological components (that express trait values independent of phylogenetic relationships). At the habitat scale, bromeliad spiders were larger and flatter than spiders associated with the surrounding dicots. At this scale, plant morphology sorted out close related spiders. Our results showed that spider flatness is phylogenetically clustered at the habitat scale, whereas it is phylogenetically overdispersed at the microhabitat scale, although phylogenic signal is present in both scales. Taken together, these results suggest that whereas at the habitat scale selective colonization affect spider body size and shape, at fine scales both selective colonization and adaptive evolution determine spider body shape. By partitioning the phylogenetic and ecological components of phenotypic variation, we were able to disentangle the evolutionary history of distinct spider traits and show that plant architecture plays a role in the evolution of spider body size and shape. We also discussed the relevance in considering multiple scales when studying phylogenetic community structure.

  16. Uncovering the structure-function relationship in spider silk

    Yarger, Jeffery L.; Cherry, Brian R.; van der Vaart, Arjan

    2018-03-01

    All spiders produce protein-based biopolymer fibres that we call silk. The most studied of these silks is spider dragline silk, which is very tough and relatively abundant compared with other types of spider silks. Considerable research has been devoted to understanding the relationship between the molecular structure and mechanical properties of spider dragline silks. In this Review, we overview experimental and computational studies that have provided a wealth of detail at the molecular level on the highly conserved repetitive core and terminal regions of spider dragline silk. We also discuss the role of the nanocrystalline β-sheets and amorphous regions in determining the properties of spider silk fibres, endowing them with strength and elasticity. Additionally, we outline imaging techniques and modelling studies that elucidate the importance of the hierarchical structure of silk fibres at the molecular level. These insights into structure-function relationships can guide the reverse engineering of spider silk to enable the production of superior synthetic fibres.

  17. Checklist of spider fauna of FR Peshawar, FATA, Pakistan

    F. Perveen

    2012-03-01

    Full Text Available The spiders are known as poisonous arthropods, but they also act as the predator or biological pests control agent. Their 23 species belonging to 15 genera and 09 families were reported during 2009-2010 from FR Peshawar, FATA, Pakistan. The reported families Clubionidae, Scytodidae and Sprassidae covered each 4%, Araneidae, Gnaphosidae, Pholicidae and Salticidae each 9%, Thomisidae 13% and Lycosidae 43% biodiversity of spiders of FATA. However, the largest spider collected was huntsman, Isopoda tuhodnigra (Barrion with total body length 15.80+-0.83 mm. Moreover, the smallest spider was wolf spider, Pardosa birmanica (Simon with total body length 4.20+-1.30 mm. Further, the crab spiders, Thomisus pugilis (Stoliczka, T. spectabilis (Doleschall and Diaea evanida (Thorell were the most colorful species belonging to family Thomisidae. A detail study is required for further exploration of spider fauna of FATA.

  18. Multi-probe-based resonance-frequency electrical impedance spectroscopy for detection of suspicious breast lesions: improving performance using partial ROC optimization

    Lederman, Dror; Zheng, Bin; Wang, Xingwei; Wang, Xiao Hui; Gur, David

    2011-03-01

    We have developed a multi-probe resonance-frequency electrical impedance spectroscope (REIS) system to detect breast abnormalities. Based on assessing asymmetry in REIS signals acquired between left and right breasts, we developed several machine learning classifiers to classify younger women (i.e., under 50YO) into two groups of having high and low risk for developing breast cancer. In this study, we investigated a new method to optimize performance based on the area under a selected partial receiver operating characteristic (ROC) curve when optimizing an artificial neural network (ANN), and tested whether it could improve classification performance. From an ongoing prospective study, we selected a dataset of 174 cases for whom we have both REIS signals and diagnostic status verification. The dataset includes 66 "positive" cases recommended for biopsy due to detection of highly suspicious breast lesions and 108 "negative" cases determined by imaging based examinations. A set of REIS-based feature differences, extracted from the two breasts using a mirror-matched approach, was computed and constituted an initial feature pool. Using a leave-one-case-out cross-validation method, we applied a genetic algorithm (GA) to train the ANN with an optimal subset of features. Two optimization criteria were separately used in GA optimization, namely the area under the entire ROC curve (AUC) and the partial area under the ROC curve, up to a predetermined threshold (i.e., 90% specificity). The results showed that although the ANN optimized using the entire AUC yielded higher overall performance (AUC = 0.83 versus 0.76), the ANN optimized using the partial ROC area criterion achieved substantially higher operational performance (i.e., increasing sensitivity level from 28% to 48% at 95% specificity and/ or from 48% to 58% at 90% specificity).

  19. Recombinant DNA production of spider silk proteins.

    Tokareva, Olena; Michalczechen-Lacerda, Valquíria A; Rech, Elíbio L; Kaplan, David L

    2013-11-01

    Spider dragline silk is considered to be the toughest biopolymer on Earth due to an extraordinary combination of strength and elasticity. Moreover, silks are biocompatible and biodegradable protein-based materials. Recent advances in genetic engineering make it possible to produce recombinant silks in heterologous hosts, opening up opportunities for large-scale production of recombinant silks for various biomedical and material science applications. We review the current strategies to produce recombinant spider silks. © 2013 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology.

  20. Programming spiders, bots, and aggregators in Java

    Heaton, Jeff

    2006-01-01

    The content and services available on the web continue to be accessed mostly through direct human control. But this is changing. Increasingly, users rely on automated agents that save them time and effort by programmatically retrieving content, performing complex interactions, and aggregating data from diverse sources. Programming Spiders, Bots, and Aggregators in Java teaches you how to build and deploy a wide variety of these agents-from single-purpose bots to exploratory spiders to aggregators that present a unified view of information from multiple user accounts. You will quickly build on

  1. Numerical implementation of multiple peeling theory and its application to spider web anchorages.

    Brely, Lucas; Bosia, Federico; Pugno, Nicola M

    2015-02-06

    Adhesion of spider web anchorages has been studied in recent years, including the specific functionalities achieved through different architectures. To better understand the delamination mechanisms of these and other biological or artificial fibrillar adhesives, and how their adhesion can be optimized, we develop a novel numerical model to simulate the multiple peeling of structures with arbitrary branching and adhesion angles, including complex architectures. The numerical model is based on a recently developed multiple peeling theory, which extends the energy-based single peeling theory of Kendall, and can be applied to arbitrarily complex structures. In particular, we numerically show that a multiple peeling problem can be treated as the superposition of single peeling configurations even for complex structures. Finally, we apply the developed numerical approach to study spider web anchorages, showing how their function is achieved through optimal geometrical configurations.

  2. Scavenging by spiders (Araneae) and its relationship to pest management of the brown recluse spider.

    Vetter, Richard S

    2011-06-01

    Experiments reported in Sandidge (2003; Nature 426: 30) indicated that the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, preferred to scavenge dead prey over live prey and that the spiders were not detrimentally affected when fed insecticide-killed crickets. Extrapolations made in subsequent media coverage disseminating the results of this research made counter-intuitive statements that pesticide treatment in houses would increase brown recluse populations in homes. This information was presented as if the scavenging behavior was specialized in the brown recluse; however, it was more likely that this behavior has not been well studied in other species. To provide a comparison, the current laboratory study examined the likelihood of non-Loxosceles spiders to scavenge dead prey. Of 100 non-Loxosceles spiders that were tested (from 11 families, 24 genera, and at least 29 species from a variety of spider hunting guilds), 99 scavenged dead crickets when offered in petri dishes. Some of the spiders were webspinners in which real-world scavenging of dead prey is virtually impossible, yet they scavenge when given the opportunity. Therefore, scavenging is a flexible opportunistic predatory behavior that is spread across a variety of taxa and is not a unique behavior in brown recluses. These findings are discussed in relation to pest management practices.

  3. SignalSpider: Probabilistic pattern discovery on multiple normalized ChIP-Seq signal profiles

    Wong, Kachun

    2014-09-05

    Motivation: Chromatin immunoprecipitation (ChIP) followed by high-throughput sequencing (ChIP-Seq) measures the genome-wide occupancy of transcription factors in vivo. Different combinations of DNA-binding protein occupancies may result in a gene being expressed in different tissues or at different developmental stages. To fully understand the functions of genes, it is essential to develop probabilistic models on multiple ChIP-Seq profiles to decipher the combinatorial regulatory mechanisms by multiple transcription factors. Results: In this work, we describe a probabilistic model (SignalSpider) to decipher the combinatorial binding events of multiple transcription factors. Comparing with similar existing methods, we found SignalSpider performs better in clustering promoter and enhancer regions. Notably, SignalSpider can learn higher-order combinatorial patterns from multiple ChIP-Seq profiles. We have applied SignalSpider on the normalized ChIP-Seq profiles from the ENCODE consortium and learned model instances. We observed different higher-order enrichment and depletion patterns across sets of proteins. Those clustering patterns are supported by Gene Ontology (GO) enrichment, evolutionary conservation and chromatin interaction enrichment, offering biological insights for further focused studies. We also proposed a specific enrichment map visualization method to reveal the genome-wide transcription factor combinatorial patterns from the models built, which extend our existing fine-scale knowledge on gene regulation to a genome-wide level. Availability and implementation: The matrix-algebra-optimized executables and source codes are available at the authors\\' websites: http://www.cs.toronto.edu/∼wkc/SignalSpider. Contact: Supplementary information: Supplementary data are available at Bioinformatics online.

  4. Viscoelastic nanoscale properties of cuticle contribute to the high-pass properties of spider vibration receptor (Cupiennius salei Keys)

    McConney, Michael E; Schaber, Clemens F; Julian, Michael D; Barth, Friedrich G; Tsukruk, Vladimir V

    2007-01-01

    Atomic force microscopy (AFM) and surface force spectroscopy were applied in live spiders to their joint pad material located distal of the metatarsal lyriform organs, which are highly sensitive vibration sensors. The surface topography of the material is sufficiently smooth to probe the local nanomechanical properties with nanometre elastic deflections. Nanoscale loads were applied in the proximad direction on the distal joint region simulating the natural stimulus situation. The force curve...

  5. Mobile Probing and Probes

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff Mathiasen, Anne-Gitte

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  6. Mobile Probing and Probes

    Duvaa, Uffe; Ørngreen, Rikke; Weinkouff, Anne-Gitte

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  7. Spider and burnable poison rod combinations

    Walton, L.A.

    1980-01-01

    A description is given of an improved design of burnable poison rods and their associated spiders used in the fuel assemblies of pressurized water power reactor cores which allows the rods to be installed and removed more quickly, simply and gently than in previously described systems. (U.K.)

  8. The aerodynamic signature of running spiders.

    Jérôme Casas

    Full Text Available Many predators display two foraging modes, an ambush strategy and a cruising mode. These foraging strategies have been classically studied in energetic, biomechanical and ecological terms, without considering the role of signals produced by predators and perceived by prey. Wolf spiders are a typical example; they hunt in leaf litter either using an ambush strategy or by moving at high speed, taking over unwary prey. Air flow upstream of running spiders is a source of information for escaping prey, such as crickets and cockroaches. However, air displacement by running arthropods has not been previously examined. Here we show, using digital particle image velocimetry, that running spiders are highly conspicuous aerodynamically, due to substantial air displacement detectable up to several centimetres in front of them. This study explains the bimodal distribution of spider's foraging modes in terms of sensory ecology and is consistent with the escape distances and speeds of cricket prey. These findings may be relevant to the large and diverse array of arthropod prey-predator interactions in leaf litter.

  9. SPiDer: Smart Pill Dispenser

    Moreno Vázquez, Jonatan

    2013-01-01

    Aquest projecte proposa el sistema SPiDer el qual te l'objectiu d'assistir a la gent gran en el procés de medicar-se evitant els problemes associats amb la baixa adherència existent actualment amb els calendaris farmacològics receptats pels doctors.

  10. Status of the CNESM diagnostic for SPIDER

    Muraro, A.; Croci, G.; Albani, G.; Cazzaniga, C.; Claps, G.; Cavenago, M.; Grosso, G.; Palma, M. Dalla; Fincato, M.; Murtas, F.; Pasqualotto, R.; Cippo, E. Perelli; Rebai, M.; Tollin, M.; Tardocchi, M.; Gorini, G.

    2015-01-01

    Highlights: • We have finished the design of the detector box of the CNESM diagnostic for SPIDER. • We have constructed the GEM detector of the CNESM detector for SPIDER. • We have tested the detector under fast neutron irradiation. - Abstract: The ITER neutral beam test facility under construction in Padova will host two experimental devices: SPIDER, a 100 kV negative H/D RF source, and MITICA, a full scale, 1 MeV deuterium beam injector. A detection system called close-contact neutron emission surface mapping (CNESM) is under development with the aim to resolve the horizontal beam intensity profile in MITICA and one of the eight beamlet groups in SPIDER, with a spatial resolution of 1.5 and 2.5 cm respectively. This is achieved by the evaluation of the map of the neutron emission due to interaction of the deuterium beam with the deuterons implanted in the beam dump surface. CNESM uses nGEM detectors, i.e. GEM detectors equipped with a cathode that also serves as neutron–proton converter foil. The diagnostic will be placed right behind the SPIDER and MITICA beam dump, i.e. in an UHV environment, but the nGEM detectors need to operate at atmospheric pressure: in order to maintain the detector at atmospheric pressure, a vacuum sealed box, that will be mounted inside the vacuum, has been designed. The box design was driven by the need to minimize the neutron attenuation and the distance between the beam dump surface and the detector active area. This paper presents the status of the CNESM diagnostic describing the design of the detector, the design of the sealed box and reporting the results obtained with the first full-size prototype under fast neutron irradiation.

  11. The response of spider (Araneae assemblages to structural heterogeneity and prey abundance in sub-montane vegetation modified by conservation grazing

    Peter Dennis

    2015-01-01

    Full Text Available The effect of experimental livestock grazing regimens (4 treatments×6 replicates on spiders via habitat structure and prey abundance was investigated on sub-montane habitats in the Southern Highlands of Scotland. The study, 2002–2004 included a baseline survey under the prior, commercial sheep grazing regimen and two assessments of spider assemblages post-treatment: commercial stocking density of sheep; 1/3 stocking density with sheep; 1/3 stocking density cattle with sheep; and no grazing. Spiders were sampled with a suction sampler, five sucks at each of 25 sample units by 24 plots (600 samples in 2003 and 2004, ca. 320 in 2002. Spider abundance and species richness increased under reduced stocking density, mixed herbivore and ungrazed treatments indirectly via changes in vegetation structure and prey abundance. The results refuted a meta-analysis that concluded species richness of spiders is unaffected by grazing. Grazing regimens caused turnover in species composition more than the net difference in species richness suggested, implying that no single, optimal grazing regimen will support as many species as a patchwork under varied grazing management. Conservation grazing benefits spiders and will have significant benefits for food webs in sub-montane ecosystems but the period to equilibrium after changes to grazing requires further investigation.

  12. A novel neurotoxin from venom of the spider, Brachypelma albopilosum.

    Yunhua Zhong

    Full Text Available Spiders have evolved highly selective toxins for insects. There are many insecticidal neurotoxins in spider venoms. Although a large amount of work has been done to focus on neurotoxicity of spider components, little information, which is related with effects of spider toxins on tumor cell proliferation and cytotoxicity, is available for Brachypelma albopilosum venom. In this work, a novel spider neurotoxin (brachyin was identified and characterized from venoms of the spider, Brachypelma albopilosum. Brachyin is composed of 41 amino acid residues with the sequence of CLGENVPCDKDRPNCCSRYECLEPTGYGWWYASYYCYKKRS. There are six cysteines in this sequence, which form three disulfided bridges. The serine residue at the C-terminus is amidated. Brachyin showed strong lethal effects on American cockroaches (Periplaneta americana and Tenebrio molitor (common mealbeetle. This neurotoxin also showed significant analgesic effects in mice models including abdominal writhing induced by acetic acid and formalin-induced paw licking tests. It was interesting that brachyin exerted marked inhibition on tumor cell proliferation.

  13. Chromosome mapping of dragline silk genes in the genomes of widow spiders (Araneae, Theridiidae.

    Yonghui Zhao

    Full Text Available With its incredible strength and toughness, spider dragline silk is widely lauded for its impressive material properties. Dragline silk is composed of two structural proteins, MaSp1 and MaSp2, which are encoded by members of the spidroin gene family. While previous studies have characterized the genes that encode the constituent proteins of spider silks, nothing is known about the physical location of these genes. We determined karyotypes and sex chromosome organization for the widow spiders, Latrodectus hesperus and L. geometricus (Araneae, Theridiidae. We then used fluorescence in situ hybridization to map the genomic locations of the genes for the silk proteins that compose the remarkable spider dragline. These genes included three loci for the MaSp1 protein and the single locus for the MaSp2 protein. In addition, we mapped a MaSp1 pseudogene. All the MaSp1 gene copies and pseudogene localized to a single chromosomal region while MaSp2 was located on a different chromosome of L. hesperus. Using probes derived from L. hesperus, we comparatively mapped all three MaSp1 loci to a single region of a L. geometricus chromosome. As with L. hesperus, MaSp2 was found on a separate L. geometricus chromosome, thus again unlinked to the MaSp1 loci. These results indicate orthology of the corresponding chromosomal regions in the two widow genomes. Moreover, the occurrence of multiple MaSp1 loci in a conserved gene cluster across species suggests that MaSp1 proliferated by tandem duplication in a common ancestor of L. geometricus and L. hesperus. Unequal crossover events during recombination could have given rise to the gene copies and could also maintain sequence similarity among gene copies over time. Further comparative mapping with taxa of increasing divergence from Latrodectus will pinpoint when the MaSp1 duplication events occurred and the phylogenetic distribution of silk gene linkage patterns.

  14. The study of the elasticity of spider dragline silk with liquid crystal model

    Cui Linying; Liu Fei; Ouyang Zhongcan

    2009-01-01

    Spider dragline silk is an optimal biomaterial with a combination of high tensile strength and high elasticity, and it has long been suggested to belong to liquid crystalline materials. However, a satisfactory liquid crystal description for the mechanical properties of the dragline is still missing. To solve the long existing problem, we generalized the Maier-Saupe theory of nematics to construct a liquid crystal model of the deformation mechanism of the dragline silk. We show that the remarkable elasticity of the dragline can be understood as the isotropic-nematic phase transition of the chain network with the beginning of the transition corresponding to the yield point. The calculated curve fits well with the measurements and the yield point is obtained self-consistently within our framework. The present theory can also qualitatively account for the drop of stress in supercontracted spider silk. All these comprehensive agreements between theory and experiments strongly indicate the dragline to belong to liquid crystal materials.

  15. Attention and amygdala activity: an fMRI study with spider pictures in spider phobia.

    Alpers, Georg W; Gerdes, Antje B M; Lagarie, Bernadette; Tabbert, Katharina; Vaitl, Dieter; Stark, Rudolf

    2009-06-01

    Facilitated detection of threatening visual cues is thought to be adaptive. In theory, detection of threat cues should activate the amygdala independently from allocation of attention. However, previous studies using emotional facial expressions as well as phobic cues yielded contradictory results. We used fMRI to examine whether the allocation of attention to components of superimposed spider and bird displays modulates amygdala activation. Nineteen spider-phobic women were instructed to identify either a moving or a stationary animal in briefly presented double-exposure displays. Amygdala activation followed a dose-response relationship: Compared to congruent neutral displays (two birds), amygdala activation was most pronounced in response to congruent phobic displays (two spiders) and less but still significant in response to mixed displays (spider and bird) when attention was focused on the phobic component. When attention was focused on the neutral component, mixed displays did not result in significant amygdala activation. This was confirmed in a significant parametric graduation of the amygdala activation in the order of congruent phobic displays, mixed displays with attention focus on the spider, mixed displays with focus on the bird and congruent neutral displays. These results challenge the notion that amygdala activation in response to briefly presented phobic cues is independent from attention.

  16. What you fear will appear: detection of schematic spiders in spider fear.

    Peira, Nathalie; Golkar, Armita; Larsson, Maria; Wiens, Stefan

    2010-01-01

    Various experimental tasks suggest that fear guides attention. However, because these tasks often lack ecological validity, it is unclear to what extent results from these tasks can be generalized to real-life situations. In change detection tasks, a brief interruption of the visual input (i.e., a blank interval or a scene cut) often results in undetected changes in the scene. This setup resembles real-life viewing behavior and is used here to increase ecological validity of the attentional task without compromising control over the stimuli presented. Spider-fearful and nonfearful women detected schematic spiders and flowers that were added to one of two identical background pictures that alternated with a brief blank in between them (i.e., flicker paradigm). Results showed that spider-fearful women detected spiders (but not flowers) faster than did nonfearful women. Because spiders and flowers had similar low-level features, these findings suggest that fear guides attention on the basis of object features rather than simple low-level features.

  17. Learning to avoid spiders: fear predicts performance, not competence.

    Luo, Xijia; Becker, Eni S; Rinck, Mike

    2018-01-05

    We used an immersive virtual environment to examine avoidance learning in spider-fearful participants. In 3 experiments, participants were asked to repeatedly lift one of 3 virtual boxes, under which either a toy car or a spider appeared and then approached the participant. Participants were not told that the probability of encountering a spider differed across boxes. When the difference was large (Exps. 1 and 2), spider-fearfuls learned to avoid spiders by lifting the few-spiders-box more often and the many-spiders-box less often than non-fearful controls did. However, they hardly managed to do so when the probability differences were small (Exp. 3), and they did not escape from threat more quickly (Exp. 2). In contrast to the observed performance differences, spider-fearfuls and non-fearfuls showed equal competence, that is comparable post-experimental knowledge about the probability to encounter spiders under the 3 boxes. The limitations and implications of the present study are discussed.

  18. Sex-specific kleptoparasitic foraging in ant-eating spiders

    Martisová, Martina; Bilde, T.; Pekar, Stano

    2009-01-01

    . To investigate this hypothesis, we studied the effect of sex and life history stage on the frequency of kleptoparasitism in ant-eating spiders of the genus Zodarion in the field. These spiders use a special capture technique involving a quick attack on an ant that is left unguarded by spiders for several minutes......, providing ample opportunities for kleptoparasitism. We found that adult females consistently hunted actively, while adult males ceased active prey capture and instead engaged in kleptoparasitism. Juvenile spiders were active hunters irrespective of sex. Consistent with an ontogenetic shift in foraging...

  19. Second-order nonlinear optical microscopy of spider silk

    Zhao, Yue; Hien, Khuat Thi Thu; Mizutani, Goro; Rutt, Harvey N.

    2017-06-01

    Asymmetric β-sheet protein structures in spider silk should induce nonlinear optical interaction such as second harmonic generation (SHG) which is experimentally observed for a radial line and dragline spider silk using an imaging femtosecond laser SHG microscope. By comparing different spider silks, we found that the SHG signal correlates with the existence of the protein β-sheets. Measurements of the polarization dependence of SHG from the dragline indicated that the β-sheet has a nonlinear response depending on the direction of the incident electric field. We propose a model of what orientation the β-sheet takes in spider silk.

  20. Transcript profiling of common bean (Phaseolus vulgaris L. using the GeneChip® Soybean Genome Array: optimizing analysis by masking biased probes

    Gronwald John W

    2010-05-01

    Full Text Available Abstract Background Common bean (Phaseolus vulgaris L. and soybean (Glycine max both belong to the Phaseoleae tribe and share significant coding sequence homology. This suggests that the GeneChip® Soybean Genome Array (soybean GeneChip may be used for gene expression studies using common bean. Results To evaluate the utility of the soybean GeneChip for transcript profiling of common bean, we hybridized cRNAs purified from nodule, leaf, and root of common bean and soybean in triplicate to the soybean GeneChip. Initial data analysis showed a decreased sensitivity and accuracy of measuring differential gene expression in common bean cross-species hybridization (CSH GeneChip data compared to that of soybean. We employed a method that masked putative probes targeting inter-species variable (ISV regions between common bean and soybean. A masking signal intensity threshold was selected that optimized both sensitivity and accuracy of measuring differential gene expression. After masking for ISV regions, the number of differentially-expressed genes identified in common bean was increased by 2.8-fold reflecting increased sensitivity. Quantitative RT-PCR (qRT-PCR analysis of 20 randomly selected genes and purine-ureide pathway genes demonstrated an increased accuracy of measuring differential gene expression after masking for ISV regions. We also evaluated masked probe frequency per probe set to gain insight into the sequence divergence pattern between common bean and soybean. The sequence divergence pattern analysis suggested that the genes for basic cellular functions and metabolism were highly conserved between soybean and common bean. Additionally, our results show that some classes of genes, particularly those associated with environmental adaptation, are highly divergent. Conclusions The soybean GeneChip is a suitable cross-species platform for transcript profiling in common bean when used in combination with the masking protocol described. In

  1. Recent advances in the understanding of brown spider venoms: From the biology of spiders to the molecular mechanisms of toxins.

    Gremski, Luiza Helena; Trevisan-Silva, Dilza; Ferrer, Valéria Pereira; Matsubara, Fernando Hitomi; Meissner, Gabriel Otto; Wille, Ana Carolina Martins; Vuitika, Larissa; Dias-Lopes, Camila; Ullah, Anwar; de Moraes, Fábio Rogério; Chávez-Olórtegui, Carlos; Barbaro, Katia Cristina; Murakami, Mario Tyago; Arni, Raghuvir Krishnaswamy; Senff-Ribeiro, Andrea; Chaim, Olga Meiri; Veiga, Silvio Sanches

    2014-06-01

    The Loxosceles genus spiders (the brown spiders) are encountered in all the continents, and the clinical manifestations following spider bites include skin necrosis with gravitational lesion spreading and occasional systemic manifestations, such as intravascular hemolysis, thrombocytopenia and acute renal failure. Brown spider venoms are complex mixtures of toxins especially enriched in three molecular families: the phospholipases D, astacin-like metalloproteases and Inhibitor Cystine Knot (ICK) peptides. Other toxins with low level of expression also present in the venom include the serine proteases, serine protease inhibitors, hyaluronidases, allergen factors and translationally controlled tumor protein (TCTP). The mechanisms by which the Loxosceles venoms act and exert their noxious effects are not fully understood. Except for the brown spider venom phospholipase D, which causes dermonecrosis, hemolysis, thrombocytopenia and renal failure, the pathological activities of the other venom toxins remain unclear. The objective of the present review is to provide insights into the brown spider venoms and loxoscelism based on recent results. These insights include the biology of brown spiders, the clinical features of loxoscelism and the diagnosis and therapy of brown spider bites. Regarding the brown spider venom, this review includes a description of the novel toxins revealed by molecular biology and proteomics techniques, the data regarding three-dimensional toxin structures, and the mechanism of action of these molecules. Finally, the biotechnological applications of the venom components, especially for those toxins reported as recombinant molecules, and the challenges for future study are discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Araneae Sloveniae: a national spider species checklist.

    Kostanjšek, Rok; Kuntner, Matjaž

    2015-01-01

    The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe.

  3. Logic circuits based on molecular spider systems.

    Mo, Dandan; Lakin, Matthew R; Stefanovic, Darko

    2016-08-01

    Spatial locality brings the advantages of computation speed-up and sequence reuse to molecular computing. In particular, molecular walkers that undergo localized reactions are of interest for implementing logic computations at the nanoscale. We use molecular spider walkers to implement logic circuits. We develop an extended multi-spider model with a dynamic environment wherein signal transmission is triggered via localized reactions, and use this model to implement three basic gates (AND, OR, NOT) and a cascading mechanism. We develop an algorithm to automatically generate the layout of the circuit. We use a kinetic Monte Carlo algorithm to simulate circuit computations, and we analyze circuit complexity: our design scales linearly with formula size and has a logarithmic time complexity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  4. Araneae Sloveniae: a national spider species checklist

    Rok Kostanjšek

    2015-01-01

    Full Text Available The research of the spider fauna of Slovenia dates back to the very beginning of binomial nomenclature, and has gone through more and less prolific phases with authors concentrating on taxonomy, faunistics, ecology and zoogeographic reviews. Although the body of published works is remarkable for a small nation, the faunistic data has remained too scattered for a thorough understanding of regional biotic diversity, for comparative and ecological research, and for informed conservation purposes. A national checklist is long overdue. Here, a critical review of all published records in any language is provided. The species list currently comprises 738 species, is published online at http://www.bioportal.si/katalog/araneae.php under the title Araneae Sloveniae, and will be updated in due course. This tool will fill the void in cataloguing regional spider faunas and will facilitate further araneological research in central and southern Europe.

  5. Nanofibre production in spiders without electric charge.

    Joel, Anna-Christin; Baumgartner, Werner

    2017-06-15

    Technical nanofibre production is linked to high voltage, because nanofibres are typically produced by electrospinning. In contrast, spiders have evolved a way to produce nanofibres without high voltage. These spiders are called cribellate spiders and produce nanofibres within their capture thread production. It is suggested that their nanofibres become frictionally charged when brushed over a continuous area on the calamistrum, a comb-like structure at the metatarsus of the fourth leg. Although there are indications that electrostatic charges are involved in the formation of the thread structure, final proof is missing. We proposed three requirements to validate this hypothesis: (1) the removal of any charge during or after thread production has an influence on the structure of the thread; (2) the characteristic structure of the thread can be regenerated by charging; and (3) the thread is attracted to or repelled from differently charged objects. None of these three requirements were proven true. Furthermore, mathematical calculations reveal that even at low charges, the calculated structural assembly of the thread does not match the observed reality. Electrostatic forces are therefore not involved in the production of cribellate capture threads. © 2017. Published by The Company of Biologists Ltd.

  6. Optimal clinical time for reliable measurement of transcutaneous CO2 with ear probes: counterbalancing overshoot and the vasodilatation effect.

    Domingo, Christian; Canturri, Elisa; Moreno, Amalia; Espuelas, Humildad; Vigil, Laura; Luján, Manel

    2010-01-01

    To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO(2)) and transcutaneous CO(2) (TcPCO(2)) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO(2)). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO(2) and TcPCO(2) with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1-1.9 mm Hg); (b) moderate (2-4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO(2) and TcPCO(2) and arterial values of PaCO(2) and SpO(2). The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV(1): 72.9 ± 23.9%; FEV(1)/FVC: 70 ± 15.5%. ABG: PaO(2): 82.6 ± 13.2; PaCO(2): 39.9.1 ± 4.8 mmHg; SaO(2): 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO(2) was -0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO(2), measurements were reliable at minute 2. The optimal clinical reading measurement recommended for the ear lobe TcPCO(2) measurement ranges between minute 12 and 14. The SpO(2) measurement can be performed at minute 2.

  7. Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect

    Manel Luján

    2010-01-01

    Full Text Available OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO and transcutaneous CO2 (TcPCO2 in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2. EXPERIMENTAL SECTION: Observational study of 91 (75 men individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG analysis. Overshoot severity: (a mild (0.1–1.9 mm Hg; (b moderate (2–4.9 mm Hg; (c severe: (>5 mm Hg. The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3% patients, moderate in 20 (22% and severe in nine (10%; no overshoot was observed in 29 (31% patients. The lowest mean differences between arterial blood gas and TcPCO2 was –0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8. The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2.

  8. Optimal Clinical Time for Reliable Measurement of Transcutaneous CO2 with Ear Probes: Counterbalancing Overshoot and the Vasodilatation Effect

    Domingo, Christian; Canturri, Elisa; Moreno, Amalia; Espuelas, Humildad; Vigil, Laura; Luján, Manel

    2010-01-01

    OBJECTIVES: To determine the optimal clinical reading time for the transcutaneous measurement of oxygen saturation (SpO2) and transcutaneous CO2 (TcPCO2) in awake spontaneously breathing individuals, considering the overshoot phenomenon (transient overestimation of arterial PaCO2). EXPERIMENTAL SECTION: Observational study of 91 (75 men) individuals undergoing forced spirometry, measurement of SpO2 and TcPCO2 with the SenTec monitor every two minutes until minute 20 and arterial blood gas (ABG) analysis. Overshoot severity: (a) mild (0.1–1.9 mm Hg); (b) moderate (2–4.9 mm Hg); (c) severe: (>5 mm Hg). The mean difference was calculated for SpO2 and TcPCO2 and arterial values of PaCO2 and SpO2. The intraclass correlation coefficient (ICC) between monitor readings and blood values was calculated as a measure of agreement. RESULTS: The mean age was 63.1 ± 11.8 years. Spirometric values: FVC: 75.4 ± 6.2%; FEV1: 72.9 ± 23.9%; FEV1/FVC: 70 ± 15.5%. ABG: PaO2: 82.6 ± 13.2; PaCO2: 39.9.1 ± 4.8 mmHg; SaO2: 95.3 ± 4.4%. Overshoot analysis: overshoot was mild in 33 (36.3%) patients, moderate in 20 (22%) and severe in nine (10%); no overshoot was observed in 29 (31%) patients. The lowest mean differences between arterial blood gas and TcPCO2 was −0.57 mmHg at minute 10, although the highest ICC was obtained at minutes 12 and 14 (>0.8). The overshoot lost its influence after minute 12. For SpO2, measurements were reliable at minute 2. CONCLUSIONS: The optimal clinical reading measurement recommended for the ear lobe TcPCO2 measurement ranges between minute 12 and 14. The SpO2 measurement can be performed at minute 2. PMID:22315552

  9. Transcript profiling of two alfalfa genotypes with contrasting cell wall composition in stems using a cross-species platform: optimizing analysis by masking biased probes

    Jung Hans-Joachim G

    2010-05-01

    Full Text Available Abstract Background The GeneChip® Medicago Genome Array, developed for Medicago truncatula, is a suitable platform for transcript profiling in tetraploid alfalfa [Medicago sativa (L. subsp. sativa]. However, previous research involving cross-species hybridization (CSH has shown that sequence variation between two species can bias transcript profiling by decreasing sensitivity (number of expressed genes detected and the accuracy of measuring fold-differences in gene expression. Results Transcript profiling using the Medicago GeneChip® was conducted with elongating stem (ES and post-elongation stem (PES internodes from alfalfa genotypes 252 and 1283 that differ in stem cell wall concentrations of cellulose and lignin. A protocol was developed that masked probes targeting inter-species variable (ISV regions of alfalfa transcripts. A probe signal intensity threshold was selected that optimized both sensitivity and accuracy. After masking for both ISV regions and previously identified single-feature polymorphisms (SFPs, the number of differentially expressed genes between the two genotypes in both ES and PES internodes was approximately 2-fold greater than the number detected prior to masking. Regulatory genes, including transcription factor and receptor kinase genes that may play a role in development of secondary xylem, were significantly over-represented among genes up-regulated in 252 PES internodes compared to 1283 PES internodes. Several cell wall-related genes were also up-regulated in genotype 252 PES internodes. Real-time quantitative RT-PCR of differentially expressed regulatory and cell wall-related genes demonstrated increased sensitivity and accuracy after masking for both ISV regions and SFPs. Over 1,000 genes that were differentially expressed in ES and PES internodes of genotypes 252 and 1283 were mapped onto putative orthologous loci on M. truncatula chromosomes. Clustering simulation analysis of the differentially expressed genes

  10. Structure–Activity Relationship Study of Spider Polyamine Toxins as Inhibitors of Ionotropic Glutamate Receptors

    Xiong, Xiaofeng; Poulsen, Mette H; Hussein, Rama A

    2014-01-01

    The spider polyamine toxins Joro spider toxin-3 (JSTX-3) and Nephila polyamine toxins-1 and -8 (NPTX-1 and NPTX-8) are isolated from the venom of the orb-weaver spider Nephila clavata (Joro spider). They share a high degree of structural resemblance, their aromatic head groups being the only...

  11. Who is afraid of a black Spider(-Man)?

    Ora C. McWilliams

    2013-01-01

    An Internet post asking about Spider-Man's race in a film turned into an Internet campaign about an actor that led fans to interact with each other as well as with the actor, which in turn led to the attention of media producers, which resulted in a change in Spider-Man's race in a print comic book.

  12. Who is afraid of a black Spider(-Man?

    Ora C. McWilliams

    2013-06-01

    Full Text Available An Internet post asking about Spider-Man's race in a film turned into an Internet campaign about an actor that led fans to interact with each other as well as with the actor, which in turn led to the attention of media producers, which resulted in a change in Spider-Man's race in a print comic book.

  13. Spider diversity in relation to habitat heterogeneity and an altitudinal ...

    Using pitfall traps, wandering spiders (Arachnida: Araneae) were sampled in a nested design from three different localities in the mountainous arid ecosystem of South Sinai at low, middle, and high altitudes. Habitat type and altitude were clearly different among the three localities. Spider diversity per trap varied spatially ...

  14. Time-dependent motor properties of multipedal molecular spiders.

    Samii, Laleh; Blab, Gerhard A; Bromley, Elizabeth H C; Linke, Heiner; Curmi, Paul M G; Zuckermann, Martin J; Forde, Nancy R

    2011-09-01

    Molecular spiders are synthetic biomolecular walkers that use the asymmetry resulting from cleavage of their tracks to bias the direction of their stepping motion. Using Monte Carlo simulations that implement the Gillespie algorithm, we investigate the dependence of the biased motion of molecular spiders, along with binding time and processivity, on tunable experimental parameters, such as number of legs, span between the legs, and unbinding rate of a leg from a substrate site. We find that an increase in the number of legs increases the spiders' processivity and binding time but not their mean velocity. However, we can increase the mean velocity of spiders with simultaneous tuning of the span and the unbinding rate of a spider leg from a substrate site. To study the efficiency of molecular spiders, we introduce a time-dependent expression for the thermodynamic efficiency of a molecular motor, allowing us to account for the behavior of spider populations as a function of time. Based on this definition, we find that spiders exhibit transient motor function over time scales of many hours and have a maximum efficiency on the order of 1%, weak compared to other types of molecular motors.

  15. Evidence for competition between carnivorous plants and spiders.

    Jennings, David E; Krupa, James J; Raffel, Thomas R; Rohr, Jason R

    2010-10-07

    Several studies have demonstrated that competition between disparate taxa can be important in determining community structure, yet surprisingly, to our knowledge, no quantitative studies have been conducted on competition between carnivorous plants and animals. To examine potential competition between these taxa, we studied dietary and microhabitat overlap between pink sundews (Drosera capillaris) and wolf spiders (Lycosidae) in the field, and conducted a laboratory experiment examining the effects of wolf spiders on sundew fitness. In the field, we found that sundews and spiders had a high dietary overlap with each other and with the available arthropod prey. Associations between sundews and spiders depended on spatial scale: both sundews and spiders were found more frequently in quadrats with more abundant prey, but within quadrats, spiders constructed larger webs and located them further away from sundews as the total sundew trapping area increased, presumably to reduce competition. Spiders also constructed larger webs when fewer prey were available. In the laboratory, our experiment revealed that spiders can significantly reduce sundew fitness. Our findings suggest that members of the plant and animal kingdoms can and do compete.

  16. Are temperate canopy spiders tree-species specific?

    Mupepele, Anne-Christine; Müller, Tobias; Dittrich, Marcus; Floren, Andreas

    2014-01-01

    Arboreal spiders in deciduous and coniferous trees were investigated on their distribution and diversity. Insecticidal knock-down was used to comprehensively sample spiders from 175 trees from 2001 to 2003 in the Białowieża forest and three remote forests in Poland. We identified 140 species from 9273 adult spiders. Spider communities were distinguished between deciduous and coniferous trees. The richest fauna was collected from Quercus where beta diversity was also highest. A tree-species-specific pattern was clearly observed for Alnus, Carpinus, Picea and Pinus trees and also for those tree species that were fogged in only four or three replicates, namely Betula and Populus. This hitherto unrecognised association was mainly due to the community composition of common species identified in a Dufrene-Legendre indicator species analysis. It was not caused by spatial or temporal autocorrelation. Explaining tree-species specificity for generalist predators like spiders is difficult and has to involve physical and ecological tree parameters like linkage with the abundance of prey species. However, neither did we find a consistent correlation of prey group abundances with spiders nor could differences in spider guild composition explain the observed pattern. Our results hint towards the importance of deterministic mechanisms structuring communities of generalist canopy spiders although the casual relationship is not yet understood.

  17. Camel spider (Solifugae) use of prairie dog colonies

    Solifugids (camel spiders) are widespread throughout arid regions of western North America and are thought to be important in structuring desert arthropod communities. Despite the ubiquity of camel spiders, little is known about their ecology. Black-tailed prairie dogs (Cynomys ludovicianus) are als...

  18. Brain systems underlying encounter expectancy bias in spider phobia.

    Aue, Tatjana; Hoeppli, Marie-Eve; Piguet, Camille; Hofstetter, Christoph; Rieger, Sebastian W; Vuilleumier, Patrik

    2015-06-01

    Spider-phobic individuals are characterized by exaggerated expectancies to be faced with spiders (so-called encounter expectancy bias). Whereas phobic responses have been linked to brain systems mediating fear, little is known about how the recruitment of these systems relates to exaggerated expectancies of threat. We used fMRI to examine spider-phobic and control participants while they imagined visiting different locations in a forest after having received background information about the likelihood of encountering different animals (spiders, snakes, and birds) at these locations. Critically, imagined encounter expectancies modulated brain responses differently in phobics as compared with controls. Phobics displayed stronger negative modulation of activity in the lateral prefrontal cortex, precuneus, and visual cortex by encounter expectancies for spiders, relative to snakes or birds (within-participants analysis); these effects were not seen in controls. Between-participants correlation analyses within the phobic group further corroborated the hypothesis that these phobia-specific modulations may underlie irrationality in encounter expectancies (deviations of encounter expectancies from objective background information) in spider phobia; the greater the negative modulation a phobic participant displayed in the lateral prefrontal cortex, precuneus, and visual cortex, the stronger was her bias in encounter expectancies for spiders. Interestingly, irrationality in expectancies reflected in frontal areas relied on right rather than left hemispheric deactivations. Our data accord with the idea that expectancy biases in spider phobia may reflect deficiencies in cognitive control and contextual integration that are mediated by right frontal and parietal areas.

  19. Spider mite control and resistance management: does a genome help?

    Van Leeuwen, T.; Dermauw, W.; Grbic, M.; Tirry, L.; Feyereisen, R.

    2012-01-01

    The complete genome of the two-spotted spider mite, Tetranychus urticae, has been reported. This is the first sequenced genome of a highly polyphagous and resistant agricultural pest. The question as to what the genome offers the community working on spider mite control is addressed.

  20. Three newly recorded Linyphiid spiders (Araneae: Linyphiidae from Korea

    Sue Yeon Lee

    2018-03-01

    Full Text Available Three Linyphiid spiders, Caviphantes pseudosaxetorum Wunderlich, 1979, Erigone edentata Saito and Ono, 2001, and Savignia kawachiensis Oi, 1960, are reported for the first time from Korea with taxonomic illustrations and redescription. In this study, the genus Caviphantes Oi, 1960 is also newly recorded to Korean spider fauna.

  1. Manufacturing, assembly and tests of SPIDER Vacuum Vessel to develop and test a prototype of ITER neutral beam ion source

    Zaccaria, Pierluigi, E-mail: pierluigi.zaccaria@igi.cnr.it [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete S.p.A.), Padova (Italy); Valente, Matteo; Rigato, Wladi; Dal Bello, Samuele; Marcuzzi, Diego; Agostini, Fabio Degli; Rossetto, Federico; Tollin, Marco [Consorzio RFX (CNR, ENEA, INFN, Università di Padova, Acciaierie Venete S.p.A.), Padova (Italy); Masiello, Antonio [Fusion for Energy F4E, Barcelona (Spain); Corniani, Giorgio; Badalocchi, Matteo; Bettero, Riccardo; Rizzetto, Dario [Ettore Zanon S.p.A., Schio (VI) (Italy)

    2015-10-15

    Highlights: • The SPIDER experiment aims to qualify and optimize the ion source for ITER injectors. • The large SPIDER Vacuum Vessel was built and it is under testing at the supplier. • The main working and assembly steps for production are presented in the paper. - Abstract: The SPIDER experiment (Source for the Production of Ions of Deuterium Extracted from an RF plasma) aims to qualify and optimize the full size prototype of the negative ion source foreseen for MITICA (full size ITER injector prototype) and the ITER Heating and Current Drive Injectors. Both SPIDER and MITICA experiments are presently under construction at Consorzio RFX in Padova (I), with the financial support from IO (ITER Organization), Fusion for Energy, Italian research institutions and contributions from Japan and India Domestic Agencies. The vacuum vessel hosting the SPIDER in-vessel components (Beam Source and calorimeters) has been manufactured, assembled and tested during the last two years 2013–2014. The cylindrical vessel, about 6 m long and 4 m in diameter, is composed of two cylindrical modules and two torispherical lids at the ends. All the parts are made by AISI 304 L stainless steel. The possibility of opening/closing the vessel for monitoring, maintenance or modifications of internal components is guaranteed by bolted junctions and suitable movable support structures running on rails fixed to the building floor. A large number of ports, about one hundred, are present on the vessel walls for diagnostic and service purposes. The main working steps for construction and specific technological issues encountered and solved for production are presented in the paper. Assembly sequences and tests on site are furthermore described in detail, highlighting all the criteria and requirements for correct positioning and testing of performances.

  2. Manufacturing, assembly and tests of SPIDER Vacuum Vessel to develop and test a prototype of ITER neutral beam ion source

    Zaccaria, Pierluigi; Valente, Matteo; Rigato, Wladi; Dal Bello, Samuele; Marcuzzi, Diego; Agostini, Fabio Degli; Rossetto, Federico; Tollin, Marco; Masiello, Antonio; Corniani, Giorgio; Badalocchi, Matteo; Bettero, Riccardo; Rizzetto, Dario

    2015-01-01

    Highlights: • The SPIDER experiment aims to qualify and optimize the ion source for ITER injectors. • The large SPIDER Vacuum Vessel was built and it is under testing at the supplier. • The main working and assembly steps for production are presented in the paper. - Abstract: The SPIDER experiment (Source for the Production of Ions of Deuterium Extracted from an RF plasma) aims to qualify and optimize the full size prototype of the negative ion source foreseen for MITICA (full size ITER injector prototype) and the ITER Heating and Current Drive Injectors. Both SPIDER and MITICA experiments are presently under construction at Consorzio RFX in Padova (I), with the financial support from IO (ITER Organization), Fusion for Energy, Italian research institutions and contributions from Japan and India Domestic Agencies. The vacuum vessel hosting the SPIDER in-vessel components (Beam Source and calorimeters) has been manufactured, assembled and tested during the last two years 2013–2014. The cylindrical vessel, about 6 m long and 4 m in diameter, is composed of two cylindrical modules and two torispherical lids at the ends. All the parts are made by AISI 304 L stainless steel. The possibility of opening/closing the vessel for monitoring, maintenance or modifications of internal components is guaranteed by bolted junctions and suitable movable support structures running on rails fixed to the building floor. A large number of ports, about one hundred, are present on the vessel walls for diagnostic and service purposes. The main working steps for construction and specific technological issues encountered and solved for production are presented in the paper. Assembly sequences and tests on site are furthermore described in detail, highlighting all the criteria and requirements for correct positioning and testing of performances.

  3. SPIDER: CMB Polarimetry from the Edge of Space

    Gualtieri, R.; et al.

    2017-11-28

    SPIDER is a balloon-borne instrument designed to map the polarization of the millimeter-wave sky at large angular scales. SPIDER targets the B-mode signature of primordial gravitational waves in the cosmic microwave background (CMB), with a focus on mapping a large sky area with high fidelity at multiple frequencies. SPIDER's first longduration balloon (LDB) flight in January 2015 deployed a total of 2400 antenna-coupled Transition Edge Sensors (TESs) at 90 GHz and 150 GHz. In this work we review the design and in-flight performance of the SPIDER instrument, with a particular focus on the measured performance of the detectors and instrument in a space-like loading and radiation environment. SPIDER's second flight in December 2018 will incorporate payload upgrades and new receivers to map the sky at 285 GHz, providing valuable information for cleaning polarized dust emission from CMB maps.

  4. Nutrient regulation in a predator, the wolf spider Pardosa prativaga

    Jensen, Kim; Mayntz, David; Toft, Søren

    2011-01-01

    Nutrient balancing is well known in herbivores and omnivores, but has only recently been demonstrated in predators. To test how a predator might regulate nutrients when the prey varies in nutrient composition, we restricted juvenile Pardosa prativaga wolf spiders to diets of one of six fruit fly......, Drosophila melanogaster, prey types varying in lipid:protein composition during their second instar. We collected all fly remnants to estimate food and nutrient intake over each meal. The spiders adjusted their capture rate and nutrient extraction in response to prey mass and nutrient composition...... irrespective of energy intake. Intake was initially regulated to a constant lipid plus protein mass, but later spiders fed on prey with high proportions of protein increased consumption relative to spiders fed on other prey types. This pattern indicates that the spiders were prepared to overconsume vast...

  5. Spiders of Kerala Agricultural University Campus, Thrissur, Kerala, India

    C. K. Adarsh

    2015-12-01

    Full Text Available A total of 86 species of spiders belonging to 56 genera of 20 families have been recorded from the Kerala Agricultural University (KAU campus, Thrissur, Kerala, southern India.  This represents 5.1% of the total spiders’ species and 33.33% of the total families of spiders recorded in India.  The dominant spider family at KAU campus is Araneidae with 18 species of nine genera. Salticidae is represented by 14 species of 13 genera.  Out of 252 endemic spiders of India, 16 have been reported from KAU campus.  Guild structure analysis shows spiders belonging to seven types of feeding guilds present in KAU campus.  Orb-web builders are the dominant feeding guild accounting for 34%, followed by stalkers (22%, ground runners (20%, ambushers (8%, scattered line weavers (8%, foliage runners (7% and sheet-web builders (1%. 

  6. Optimizing the Relaxivity of MRI Probes at High Magnetic Field Strengths With Binuclear GdIII Complexes

    Loredana Leone

    2018-05-01

    Full Text Available The key criteria to optimize the relaxivity of a Gd(III contrast agent at high fields (defined as the region ≥ 1.5 T can be summarized as follows: (i the occurrence of a rotational correlation time τR in the range of ca. 0.2–0.5 ns; (ii the rate of water exchange is not critical, but a τM < 100 ns is preferred; (iii a relevant contribution from water molecules in the second sphere of hydration. In addition, the use of macrocycle-based systems ensures the formation of thermodynamically and kinetically stable Gd(III complexes. Binuclear Gd(III complexes could potentially meet these requirements. Their efficiency depends primarily on the degree of flexibility of the linker connecting the two monomeric units, the absence of local motions and the presence of contribution from the second sphere water molecules. With the aim to maximize relaxivity (per Gd over a wide range of magnetic field strengths, two binuclear Gd(III chelates derived from the well-known macrocyclic systems DOTA-monopropionamide and HPDO3A (Gd2L1 and Gd2L2, respectively were synthesized through a multistep synthesis. Chemical Exchange Saturation Transfer (CEST experiments carried out on Eu2L2 at different pH showed the occurrence of a CEST effect at acidic pH that disappears at neutral pH, associated with the deprotonation of the hydroxyl groups. Then, a complete 1H and 17O NMR relaxometric study was carried out in order to evaluate the parameters that govern the relaxivity associated with these complexes. The relaxivities of Gd2L1 and Gd2L2 (20 MHz, 298 K are 8.7 and 9.5 mM−1 s−1, respectively, +77% and +106% higher than the relaxivity values of the corresponding mononuclear GdDOTAMAP-En and GdHPDO3A complexes. A significant contribution of second sphere water molecules was accounted for the strong relaxivity enhancement of Gd2L2. MR phantom images of the dinuclear complexes compared to GdHPDO3A, recorded at 7 T, confirmed the superiority of Gd2L2. Finally, ab initio

  7. Specific predictive power of automatic spider-related affective associations for controllable and uncontrollable fear responses toward spiders

    Huijdlng, J; de Jong, PJ; Huijding, J.

    This study examined the predictive power of automatically activated spider-related affective associations for automatic and controllable fear responses. The Extrinsic Affective Simon Task (EAST; De Houwer, 2003) was used to indirectly assess automatic spider fear-related associations. The EAST and

  8. And along Came a Spider: An Attentional Bias for the Detection of Spiders in Young Children and Adults

    LoBue, Vanessa

    2010-01-01

    Spiders are among the most common targets of fears and phobias in the world. In visual search tasks, adults detect their presence more rapidly than other kinds of stimuli. Reported here is an investigation of whether young children share this attentional bias for the detection of spiders. In a series of experiments, preschoolers and adults were…

  9. Solubilization of spider silk proteins and its structural analysis using Fourier transform infrared spectroscopy

    Osbin, K.; Jayan, Manuel; Bhadrakumari, S.; Predeep, P.

    2017-06-01

    This study investigates the presence of various amide bands present in different spider silk species, which provides extraordinary physical properties. Three different spider silks were collected from Western Ghats region. The collected spider silks samples belonging to the spider Heteropoda venatoria (species 1), Hersilia savignyi (species 2) and Pholcus phalangioides (species 3). Fourier transform infrared (FTIR) spectra reveals the protein peaks in the amide I, II, and III regions in all the three types of spider silk species.

  10. The Transmission Line for the SPIDER experiment

    Boldrin, Marco; De Lorenzi, Antonio; Recchia, Mauro; Toigo, Vanni; Bonicelli, Tullio; Simon, Muriel

    2011-01-01

    The 100 keV Ion Source Test facility - Source for the Production of Ions of Deuterium Extracted from RF plasma (SPIDER) - is aimed to test the full scale prototype of the Ion Source for the ITER 1 MeV Neutral Beam Injector (NBI). The SPIDER facility requires the construction of a High Voltage Deck (HVD) and of a High Voltage Transmission Line (TL) respectively to host the Ion Source Power Supplies system polarized at 100 kV and to carry the power and signal conductors to the beam accelerator. In already existing NBI systems with beam energy above 100 keV, the TL is realized with the SF 6 Gas Insulated Line technology. In the SPIDER TL case, the presence of a large inner conductor (half meter diameter), would make the pressurized TL a complex and costly component; therefore a free air insulated solution has been proposed. The paper focuses on the design of this TL, which has to host inside the complex high potential (100 kV) inner electrode a number of power and measuring conductors and has to minimize the Electro Magnetic Interferences (EMI) produced by the frequent grids breakdowns. Finite Element (FE) analyses have been performed to verify the configuration from the electrostatic point of view, to evaluate EMI screening effectiveness and to assess the impact of the relatively high thermal dissipation of power conductors located inside the high potential electrode. Moreover, an experimental test campaign has been carried out on a TL mockup to validate the TL electrostatic configuration under DC voltage. Finally, the paper reports on the status of procurement activities for the Transmission Line.

  11. Brown spider dermonecrotic toxin directly induces nephrotoxicity

    Chaim, Olga Meiri; Sade, Youssef Bacila; Bertoni da Silveira, Rafael; Toma, Leny; Kalapothakis, Evanguedes; Chavez-Olortegui, Carlos; Mangili, Oldemir Carlos; Gremski, Waldemiro; Dietrich, Carl Peter von; Nader, Helena B.; Sanches Veiga, Silvio

    2006-01-01

    Brown spider (Loxosceles genus) venom can induce dermonecrotic lesions at the bite site and systemic manifestations including fever, vomiting, convulsions, disseminated intravascular coagulation, hemolytic anemia and acute renal failure. The venom is composed of a mixture of proteins with several molecules biochemically and biologically well characterized. The mechanism by which the venom induces renal damage is unknown. By using mice exposed to Loxosceles intermedia recombinant dermonecrotic toxin (LiRecDT), we showed direct induction of renal injuries. Microscopic analysis of renal biopsies from dermonecrotic toxin-treated mice showed histological alterations including glomerular edema and tubular necrosis. Hyalinization of tubules with deposition of proteinaceous material in the tubule lumen, tubule epithelial cell vacuoles, tubular edema and epithelial cell lysis was also observed. Leukocytic infiltration was neither observed in the glomerulus nor the tubules. Renal vessels showed no sign of inflammatory response. Additionally, biochemical analyses showed such toxin-induced changes in renal function as urine alkalinization, hematuria and azotemia with elevation of blood urea nitrogen levels. Immunofluorescence with dermonecrotic toxin antibodies and confocal microscopy analysis showed deposition and direct binding of this toxin to renal intrinsic structures. By immunoblotting with a hyperimmune dermonecrotic toxin antiserum on renal lysates from toxin-treated mice, we detected a positive signal at the region of 33-35 kDa, which strengthens the idea that renal failure is directly induced by dermonecrotic toxin. Immunofluorescence reaction with dermonecrotic toxin antibodies revealed deposition and binding of this toxin directly in MDCK epithelial cells in culture. Similarly, dermonecrotic toxin treatment caused morphological alterations of MDCK cells including cytoplasmic vacuoles, blebs, evoked impaired spreading and detached cells from each other and from

  12. Numerical simulation and optimal design of Segmented Planar Imaging Detector for Electro-Optical Reconnaissance

    Chu, Qiuhui; Shen, Yijie; Yuan, Meng; Gong, Mali

    2017-12-01

    Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) is a cutting-edge electro-optical imaging technology to realize miniaturization and complanation of imaging systems. In this paper, the principle of SPIDER has been numerically demonstrated based on the partially coherent light theory, and a novel concept of adjustable baseline pairing SPIDER system has further been proposed. Based on the results of simulation, it is verified that the imaging quality could be effectively improved by adjusting the Nyquist sampling density, optimizing the baseline pairing method and increasing the spectral channel of demultiplexer. Therefore, an adjustable baseline pairing algorithm is established for further enhancing the image quality, and the optimal design procedure in SPIDER for arbitrary targets is also summarized. The SPIDER system with adjustable baseline pairing method can broaden its application and reduce cost under the same imaging quality.

  13. Assassin bug uses aggressive mimicry to lure spider prey.

    Wignall, Anne E; Taylor, Phillip W

    2011-05-07

    Assassin bugs (Stenolemus bituberus) hunt web-building spiders by invading the web and plucking the silk to generate vibrations that lure the resident spider into striking range. To test whether vibrations generated by bugs aggressively mimic the vibrations generated by insect prey, we compared the responses of spiders to bugs with how they responded to prey, courting male spiders and leaves falling into the web. We also analysed the associated vibrations. Similar spider orientation and approach behaviours were observed in response to vibrations from bugs and prey, whereas different behaviours were observed in response to vibrations from male spiders and leaves. Peak frequency and duration of vibrations generated by bugs were similar to those generated by prey and courting males. Further, vibrations from bugs had a temporal structure and amplitude that were similar to vibrations generated by leg and body movements of prey and distinctly different to vibrations from courting males or leaves, or prey beating their wings. To be an effective predator, bugs do not need to mimic the full range of prey vibrations. Instead bugs are general mimics of a subset of prey vibrations that fall within the range of vibrations classified by spiders as 'prey'.

  14. Cuticular antifungals in spiders: density- and condition dependence.

    Daniel González-Tokman

    Full Text Available Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities. For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders.

  15. Silk elasticity as a potential constraint on spider body size.

    Rodríguez-Gironés, Miguel A; Corcobado, Guadalupe; Moya-Laraño, Jordi

    2010-10-07

    Silk is known for its strength and extensibility and has played a key role in the radiation of spiders. Individual spiders use different glands to produce silk types with unique sets of proteins. Most research has studied the properties of major ampullate and capture spiral silks and their ecological implications, while little is known about minor ampullate silk, the type used by those spider species studied to date for bridging displacements. A biomechanical model parameterised with available data shows that the minimum radius of silk filaments required for efficient bridging grows with the square root of the spider's body mass, faster than the radius of minor ampullate silk filaments actually produced by spiders. Because the morphology of spiders adapted to walking along or under silk threads is ill suited for moving on a solid surface, for these species there is a negative relationship between body mass and displacement ability. As it stands, the model suggests that spiders that use silk for their displacements are prevented from attaining a large body size if they must track their resources in space. In particular, silk elasticity would favour sexual size dimorphism because males that must use bridging lines to search for females cannot grow large. 2010 Elsevier Ltd. All rights reserved.

  16. Cuticular antifungals in spiders: density- and condition dependence.

    González-Tokman, Daniel; Ruch, Jasmin; Pulpitel, Tamara; Ponton, Fleur

    2014-01-01

    Animals living in groups face a high risk of disease contagion. In many arthropod species, cuticular antimicrobials constitute the first protective barrier that prevents infections. Here we report that group-living spiders produce cuticular chemicals which inhibit fungal growth. Given that cuticular antifungals may be costly to produce, we explored whether they can be modulated according to the risk of contagion (i.e. under high densities). For this purpose, we quantified cuticular antifungal activity in the subsocial crab spider Diaea ergandros in both natural nests and experimentally manipulated nests of varying density. We quantified the body-condition of spiders to test whether antifungal activity is condition dependent, as well as the effect of spider density on body-condition. We predicted cuticular antifungal activity to increase and body-condition to decrease with high spider densities, and that antifungal activity would be inversely related to body-condition. Contrary to our predictions, antifungal activity was neither density- nor condition-dependent. However, body-condition decreased with density in natural nests, but increased in experimental nests. We suggest that pathogen pressure is so important in nature that it maintains high levels of cuticular antifungal activity in spiders, impacting negatively on individual energetic condition. Future studies should identify the chemical structure of the isolated antifungal compounds in order to understand the physiological basis of a trade-off between disease prevention and energetic condition caused by group living, and its consequences in the evolution of sociality in spiders.

  17. First report of clinical presentation of a bite by a running spider, Philodromus sp. (Araneae: Philodromidae), with recommendations for spider bite management.

    Coetzee, Maureen; Dippenaar, Ansie; Frean, John; Hunt, Richard H

    2017-06-30

    This article describes the clinical progression of symptoms over a period of 5 days of a bite inflicted by a Philodromus sp. spider. Commonly known as 'running spiders', these are not considered to be harmful to humans. This report, however, is the first description of an actual bite by a member of this group of spiders showing cytotoxic envenomation. Management of the bites should be as recommended for other cytotoxic spider bites.

  18. Structure-function-property-design interplay in biopolymers: spider silk.

    Tokareva, Olena; Jacobsen, Matthew; Buehler, Markus; Wong, Joyce; Kaplan, David L

    2014-04-01

    Spider silks have been a focus of research for almost two decades due to their outstanding mechanical and biophysical properties. Recent advances in genetic engineering have led to the synthesis of recombinant spider silks, thus helping to unravel a fundamental understanding of structure-function-property relationships. The relationships between molecular composition, secondary structures and mechanical properties found in different types of spider silks are described, along with a discussion of artificial spinning of these proteins and their bioapplications, including the role of silks in biomineralization and fabrication of biomaterials with controlled properties. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  19. Inhibition of the spider heartbeat by gravity and vibration

    Finck, A.

    1984-01-01

    The rate and vigor of the spider heartbeat is controlled by an external pacemaker. A mechanical feature of the spider cardio-vascular system is the production of high serum pressure in the prosoma and the legs. This appears to be the source for leg extension. The lyriform organ on the patella of the leg is sensitive to vibratory and kinesthetic stimuli. This sensitivity depends upon the degree of leg extension. Thus the activity of the heart and the response characteristics of the sense receptor are related. The effect of a supra-threshold vibratory or gravitational stimulus is to produce an inhibition and a tachycardia of the spider heartbeat.

  20. Spider silk reinforced by graphene or carbon nanotubes

    Lepore, Emiliano; Bosia, Federico; Bonaccorso, Francesco; Bruna, Matteo; Taioli, Simone; Garberoglio, Giovanni; Ferrari, Andrea C.; Pugno, Nicola Maria

    2017-09-01

    Spider silk has promising mechanical properties, since it conjugates high strength (~1.5 GPa) and toughness (~150 J g-1). Here, we report the production of silk incorporating graphene and carbon nanotubes by spider spinning, after feeding spiders with the corresponding aqueous dispersions. We observe an increment of the mechanical properties with respect to pristine silk, up to a fracture strength ~5.4 GPa and a toughness modulus ~1570 J g-1. This approach could be extended to other biological systems and lead to a new class of artificially modified biological, or ‘bionic’, materials.

  1. Colonization of subterranean habitats by spiders in Central Europe

    Vlastimil Růžička

    2013-05-01

    Full Text Available Using data from the Czech Republic, we studied the distribution of spiders in soils, crevice systems, scree and caves, i.e. subterranean habitats at depths spanning from 10 cm to 100 m. In total, we found 161 species. The number of species declines with increasing habitat depth, with a major drop in species richness at the depth of 10 meters. Thirteen species exhibit morphological adaptations to life in subterranean habitats. At depths greater than 10 meters, spider assemblages are almost exclusively composed of troglomorphic species. We propose a hypothesis of evolution of troglomorphisms at spiders during Quaternary climatic cycles.

  2. Venomous snake bites, scorpions, and spiders.

    Kularatne, S A M; Senanayake, Nimal

    2014-01-01

    Neurologic dysfunction due to natural neurotoxins is an important, but neglected, public health hazard in many parts of the world, particularly in the tropics. These toxins are produced by or found among a variety of live forms that include venomous snakes, arthropods such as scorpions, spiders, centipedes, stinging insects (Hymenoptera), ticks, certain poisonous fish, shellfish, crabs, cone shells, skin secretions of dart-poison frogs, and bacterial poisons such as botulinum toxin. These toxins commonly act on neuromuscular transmission at the neuromuscular junction where acetylcholine is the neurotransmitter, but in certain situations the toxins interfere with neurotransmitters such as GABA, noradrenaline, adrenaline, dopamine, and γ-aminobutyrate. Of the toxins, α-toxins and κ-toxins (e.g., Chinese krait, Bungarus multicinctus) act on the postsynaptic membrane, blocking the receptors, whilst β-toxin (e.g., common krait, B. caeruleus) acts on the presynaptic membrane, causing impairment of acetylcholine release. Conversely, dendrotoxins of the African mamba enhance acetylcholine release. The toxins of scorpions and spiders commonly interfere with voltage-gated ion channels. Clinically, the cardinal manifestation is muscle paralysis. In severe cases respiratory paralysis could be fatal. Effective antivenoms are the mainstay of treatment of envenoming, but their lack of availability is the major concern in the regions of the globe where they are desperately needed. Interestingly, some toxins have proved to be valuable pharmaceutical agents, while some others are widely exploited to study neuromuscular physiology and pathology. © 2014 Elsevier B.V. All rights reserved.

  3. Free amino acids in spider hemolymph.

    Tillinghast, Edward K; Townley, Mark A

    2008-11-01

    We examined the free amino acid composition of hemolymph from representatives of five spider families with an interest in knowing if the amino acid profile in the hemolymph of orb-web-building spiders reflects the high demands for small organic compounds in the sticky droplets of their webs. In nearly all analyses, on both orb and non-orb builders, glutamine was the most abundant free amino acid. Glycine, taurine, proline, histidine, and alanine also tended to be well-represented in orb and non-orb builders. While indications of taxon-specific differences in amino acid composition were observed, it was not apparent that two presumptive precursors (glutamine, taurine) of orb web sticky droplet compounds were uniquely enriched in araneids (orb builders). However, total amino acid concentrations were invariably highest in the araneids and especially so in overwintering juveniles, even as several of the essential amino acids declined during this winter diapause. Comparing the data from this study with those from earlier studies revealed a number of discrepancies. The possible origins of these differences are discussed.

  4. Intracellular recording from a spider vibration receptor.

    Gingl, Ewald; Burger, Anna-M; Barth, Friedrich G

    2006-05-01

    The present study introduces a new preparation of a spider vibration receptor that allows intracellular recording of responses to natural mechanical or electrical stimulation of the associated mechanoreceptor cells. The spider vibration receptor is a lyriform slit sense organ made up of 21 cuticular slits located on the distal end of the metatarsus of each walking leg. The organ is stimulated when the tarsus receives substrate vibrations, which it transmits to the organ's cuticular structures, reducing the displacement to about one tenth due to geometrical reasons. Current clamp recording was used to record action potentials generated by electrical or mechanical stimuli. Square pulse stimulation identified two groups of sensory cells, the first being single-spike cells which generated only one or two action potentials and the second being multi-spike cells which produced bursts of action potentials. When the more natural mechanical sinusoidal stimulation was applied, differences in adaptation rate between the two cell types remained. In agreement with prior extracellular recordings, both cell types showed a decrease in the threshold tarsus deflection with increasing stimulus frequency. Off-responses to mechanical stimuli have also been seen in the metatarsal organ for the first time.

  5. Spectral sensitivity of a colour changing spider.

    Defrize, Jérémy; Lazzari, Claudio R; Warrant, Eric J; Casas, Jérôme

    2011-04-01

    Vision plays a paramount role in some spider families such as the Salticidae, Lycosidae and Thomisidae, as it is involved in prey hunting, orientation or choice of substrate. In the thomisid Misumena vatia, for which the substrate colour affects the body colour, vision seems to mediate morphological colour changes. However, nothing is known about which component of visual signals from the substrate might be perceived, nor whether M. vatia possesses the physiological basis for colour vision. The aim of this study is thus to investigate the vision of this spider species by measuring the spectral sensitivities of the different pairs of eyes using electrophysiological methods. Extra- and intracellular electrophysiological recordings combined with selective adaptation revealed the presence of two classes of photoreceptor cells, one sensitive in the UV region of the spectrum (around 340 nm) and one sensitive in the green (around 520 nm) regions in the four pairs of eyes. We conclude that M. vatia possesses the physiological potential to perceive both chromatic and achromatic components of the environment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Spiders (Araneae) Found in Bananas and Other International Cargo Submitted to North American Arachnologists for Identification.

    Vetter, Richard S; Crawford, Rodney L; Buckle, Donald J

    2014-11-01

    Spiders found in international cargo brought into North America are sometimes submitted to arachnologists for identification. Often, these spiders are presumed to be of medical importance because of size or a submitter's familiarity with a toxic spider genus from the continent of origin. Starting in 2006, requests were made for spiders found in international cargo brought into North America, in addition to the specimens from similar cargo shipments already in our museum collections. This was an ad hoc study that allowed us to focus on spiders of concern to the discoverer. We identified 135 spiders found in international cargo. A key for the most common species is provided. The most frequently submitted spiders were the pantropical huntsman spider, Heteropoda venatoria (L.) (Sparassidae), and the redfaced banana spider, Cupiennius chiapanensis Medina Soriano (Ctenidae). Spiders of medical importance were rare. The most common cargo from which spiders were submitted was bananas with most specimens coming from Central America, Ecuador, or Colombia. Lack of experience with nonnative fauna caused several experienced American arachnologists to misidentify harmless ctenid spiders (C. chiapanensis, spotlegged banana spider, Cupiennius getazi Simon) as highly toxic Phoneutria spiders. These misidentifications could have led to costly, unwarranted prophylactic eradication measures, unnecessary employee health education, heightened employee anxiety and spoilage when perishable goods are left unloaded due to safety concerns. © 2014 Entomological Society of America.

  7. Phylogenomics resolves a spider backbone phylogeny and rejects a prevailing paradigm for orb web evolution.

    Bond, Jason E; Garrison, Nicole L; Hamilton, Chris A; Godwin, Rebecca L; Hedin, Marshal; Agnarsson, Ingi

    2014-08-04

    Spiders represent an ancient predatory lineage known for their extraordinary biomaterials, including venoms and silks. These adaptations make spiders key arthropod predators in most terrestrial ecosystems. Despite ecological, biomedical, and biomaterial importance, relationships among major spider lineages remain unresolved or poorly supported. Current working hypotheses for a spider "backbone" phylogeny are largely based on morphological evidence, as most molecular markers currently employed are generally inadequate for resolving deeper-level relationships. We present here a phylogenomic analysis of spiders including taxa representing all major spider lineages. Our robust phylogenetic hypothesis recovers some fundamental and uncontroversial spider clades, but rejects the prevailing paradigm of a monophyletic Orbiculariae, the most diverse lineage, containing orb-weaving spiders. Based on our results, the orb web either evolved much earlier than previously hypothesized and is ancestral for a majority of spiders or else it has multiple independent origins, as hypothesized by precladistic authors. Cribellate deinopoid orb weavers that use mechanically adhesive silk are more closely related to a diverse clade of mostly webless spiders than to the araneoid orb-weaving spiders that use adhesive droplet silks. The fundamental shift in our understanding of spider phylogeny proposed here has broad implications for interpreting the evolution of spiders, their remarkable biomaterials, and a key extended phenotype--the spider web. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Vision in the nocturnal wandering spider Leucorchestris arenicola (Araneae: Sparassidae)

    Nørgaard, Thomas; Nilsson, Dan-Eric; Henschel, Joh R

    2008-01-01

    At night the Namib Desert spider Leucorchestris arenicola performs long-distance homing across its sand dune habitat. By disabling all or pairs of the spiders' eight eyes we found that homing ability was severely reduced when vision was fully abolished. Vision, therefore, seems to play a key role...... in the posterior and anteriomedian eyes, and at approximately 540 nm in the anteriolateral eyes. Theoretical calculations of photon catches showed that the eyes are likely to employ a combination of spatial and temporal pooling in order to function at night. Under starlit conditions, the raw spatial and temporal...... resolution of the eyes is insufficient for detecting any visual information on structures in the landscape, and bright stars would be the only objects visible to the spiders. However, by summation in space and time, the spiders can rescue enough vision to detect coarse landscape structures. We show that L...

  9. 46 SPIDER WEBS AS INDICATORS OF COBALT AND LEAD ...

    Spider webs were collected from the indoor and outdoor of 120 sampling sites of 10 zones of Kano ... diet, cobalt containing ceramic is administered into ... significant human and environmental health risk. ..... Evaluation of Health Workers.

  10. Genetic diversity analysis of various red spider mite- resistant ...

    User

    2011-05-02

    May 2, 2011 ... 3Key Laboratory of Plant Breeding and Genetics, Sichuan Agricultural University, Ya'an, 625014, P. R. ... Random amplified polymorphic DNA (RAPD) is a DNA ..... spider mite-resistant, bumper, high-quality and disease-.

  11. Optical surface profiling of orb-web spider capture silks

    Kane, D M; Joyce, A M; Staib, G R [Department of Physics, Macquarie University, Sydney, NSW 2109 (Australia); Herberstein, M E, E-mail: deb.kane@mq.edu.a [Department of Biological Sciences, Macquarie University, Sydney, NSW 2109 (Australia)

    2010-09-15

    Much spider silk research to date has focused on its mechanical properties. However, the webs of many orb-web spiders have evolved for over 136 million years to evade visual detection by insect prey. It is therefore a photonic device in addition to being a mechanical device. Herein we use optical surface profiling of capture silks from the webs of adult female St Andrews cross spiders (Argiope keyserlingi) to successfully measure the geometry of adhesive silk droplets and to show a bowing in the aqueous layer on the spider capture silk between adhesive droplets. Optical surface profiling shows geometric features of the capture silk that have not been previously measured and contributes to understanding the links between the physical form and biological function. The research also demonstrates non-standard use of an optical surface profiler to measure the maximum width of a transparent micro-sized droplet (microlens).

  12. Biotechnological Trends in Spider and Scorpion Antivenom Development

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine

    2016-01-01

    in using bioactive toxins from spiders and scorpions for drug discovery purposes and for solving crystal structures of membrane-embedded receptors. Additionally, the identification and isolation of a myriad of spider and scorpion toxins has allowed research within next generation antivenoms to progress...... at an increasingly faster pace. In this review, the current knowledge of spider and scorpion venoms is presented, followed by a discussion of all published biotechnological efforts within development of spider and scorpion antitoxins based on small molecules, antibodies and fragments thereof, and next generation...... immunization strategies. The increasing number of discovery and development efforts within this field may point towards an upcoming transition from serum-based antivenoms towards therapeutic solutions based on modern biotechnology....

  13. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Yang, Liang; Hedhammar, My; Blom, Tobias; Leifer, Klaus; Johansson, Jan; Habibovic, Pamela; van Blitterswijk, Clemens

    2010-01-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently,

  14. Peculiar torsion dynamical response of spider dragline silk

    Liu, Dabiao; Yu, Longteng; He, Yuming; Peng, Kai; Liu, Jie; Guan, Juan; Dunstan, D. J.

    2017-07-01

    The torsional properties of spider dragline silks from Nephila edulis and Nephila pilipes spiders are investigated by using a torsion pendulum technique. A permanent torsional deformation is observed after even small torsional strain. This behaviour is quite different from that of the other materials tested here, i.e., carbon fiber, thin metallic wires, Kevlar fiber, and human hair. The spider dragline thus displays a strong energy dissipation upon the initial excitation (around 75% for small strains and more for a larger strain), which correspondingly reduces the amplitude of subsequent oscillations around the new equilibrium position. The variation of torsional stiffness in relaxation dynamics of spider draglines for different excitations is also determined. The experimental result is interpreted in the light of the hierarchical structure of dragline silk.

  15. Optical surface profiling of orb-web spider capture silks

    Kane, D M; Joyce, A M; Staib, G R; Herberstein, M E

    2010-01-01

    Much spider silk research to date has focused on its mechanical properties. However, the webs of many orb-web spiders have evolved for over 136 million years to evade visual detection by insect prey. It is therefore a photonic device in addition to being a mechanical device. Herein we use optical surface profiling of capture silks from the webs of adult female St Andrews cross spiders (Argiope keyserlingi) to successfully measure the geometry of adhesive silk droplets and to show a bowing in the aqueous layer on the spider capture silk between adhesive droplets. Optical surface profiling shows geometric features of the capture silk that have not been previously measured and contributes to understanding the links between the physical form and biological function. The research also demonstrates non-standard use of an optical surface profiler to measure the maximum width of a transparent micro-sized droplet (microlens).

  16. Evolution of stenophagy in spiders (Araneae): evidence based on the comparative analysis of spider diets.

    Pekár, Stano; Coddington, Jonathan A; Blackledge, Todd A

    2012-03-01

    Stenophagy (narrow diet breadth) represents an extreme of trophic specialization in carnivores, but little is known about the forces driving its evolution. We used spiders, the most diversified group of terrestrial predators, to investigate whether stenophagy (1) promoted diversification; (2) was phylogenetically conserved and evolutionarily derived state; and (3) was determined either by geographical distribution and foraging guild. We used published data on the prey of almost 600 species. Six categories of stenophagy were found: myrmecophagy, araneophagy, lepidopterophagy, termitophagy, dipterophagy, and crustaceophagy. We found that the species diversity of euryphagous genera and families was similar to stenophagous genera and families. At the family level, stenophagy evolved repeatedly and independently. Within families, the basal condition was oligophagy or euryphagy. Most types of stenophagy were clearly derived: myrmecophagy in Zodariidae; lepidopterophagy in Araneidae; dipterophagy in Theridiidae. In contrast, araneophagy was confined to basal and intermediate lineages, suggesting its ancestral condition. The diet breadth of species from the tropics and subtropics was less diverse than species from the temperate zone. Diet breadth was lower in cursorial spiders compared to web-building species. Thus, the evolution of stenophagy in spiders appears to be complex and governed by phylogeny as well as by ecological determinants. © 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.

  17. Non-pest prey do not disrupt aphid predation by a web-building spider.

    Welch, K D; Whitney, T D; Harwood, J D

    2016-02-01

    A generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

  18. Design of laser-aided diagnostics for the negative hydrogen ion source SPIDER

    Pasqualotto, R

    2012-01-01

    ITER nuclear fusion experiment requires additional heating via neutral beams by means of two injectors, delivering 16.5 MW each, up to one hour. This power level results from the neutralization of negative deuterium ions generated by an RF source and accelerated to 1 MeV. Such specifications have never been simultaneously achieved so far and therefore a test facility is being constructed at Consorzio RFX, to demonstrate the feasibility of a prototype neutral beam injector. The facility will host two experimental devices: SPIDER, a 100 kV negative hydrogen/deuterium RF source, full size prototype of the ITER source, and MITICA, a prototype of the full ITER injector. SPIDER will be devoted to optimize the extracted negative ion current density and its spatial uniformity and to minimize the co-extracted electron current. Negative hydrogen is mainly produced by conversion of hydrogen particles at the cesium coated surface of the plasma grid. The interplay of these two species is fundamental to understand and optimize the source performance. Two laser-aided diagnostics play an important role in measuring the negative hydrogen and cesium density: cavity ring down spectroscopy and laser absorption spectroscopy. Cavity ring down spectroscopy will use the photo-detachment process to measure the absolute line-of-sight integrated negative ion density in the extraction region of the source. Laser absorption spectroscopy will be employed to measure the line integrated neutral cesium density, allowing to study the cesium distribution in the source volume, during both the plasma and the vacuum phases. In this paper, the design of the laser-aided diagnostic systems on SPIDER is presented, supported by a review of results obtained in other operating experiments.

  19. Thin Film Assembly of Spider Silk-like Block Copolymers

    2011-01-01

    Shipley, N. H.; Lewis, R. V. Int. J. Biol.Macromol. 1999, 24, 271. (c) Thiel, B. L.; Guess, K. B.; Viney, C. Biopolymers 1997, 41, 703. (13) Silk ...Film Assembly of Spider Silk -like Block Copolymers Sreevidhya T. Krishnaji,†,‡ Wenwen Huang,§ Olena Rabotyagova,†,‡ Eugenia Kharlampieva, ) Ikjun Choi...Received November 26, 2010 We report the self-assembly of monolayers of spider silk -like block copolymers. Langmuir isotherms were obtained for a series of

  20. Early events in the evolution of spider silk genes.

    James Starrett

    Full Text Available Silk spinning is essential to spider ecology and has had a key role in the expansive diversification of spiders. Silk is composed primarily of proteins called spidroins, which are encoded by a multi-gene family. Spidroins have been studied extensively in the derived clade, Orbiculariae (orb-weavers, from the suborder Araneomorphae ('true spiders'. Orbicularians produce a suite of different silks, and underlying this repertoire is a history of duplication and spidroin gene divergence. A second class of silk proteins, Egg Case Proteins (ECPs, is known only from the orbicularian species, Lactrodectus hesperus (Western black widow. In L. hesperus, ECPs bond with tubuliform spidroins to form egg case silk fibers. Because most of the phylogenetic diversity of spiders has not been sampled for their silk genes, there is limited understanding of spidroin gene family history and the prevalence of ECPs. Silk genes have not been reported from the suborder Mesothelae (segmented spiders, which diverged from all other spiders >380 million years ago, and sampling from Mygalomorphae (tarantulas, trapdoor spiders and basal araneomorph lineages is sparse. In comparison to orbicularians, mesotheles and mygalomorphs have a simpler silk biology and thus are hypothesized to have less diversity of silk genes. Here, we present cDNAs synthesized from the silk glands of six mygalomorph species, a mesothele, and a non-orbicularian araneomorph, and uncover a surprisingly rich silk gene diversity. In particular, we find ECP homologs in the mesothele, suggesting that ECPs were present in the common ancestor of extant spiders, and originally were not specialized to complex with tubuliform spidroins. Furthermore, gene-tree/species-tree reconciliation analysis reveals that numerous spidroin gene duplications occurred after the split between Mesothelae and Opisthothelae (Mygalomorphae plus Araneomorphae. We use the spidroin gene tree to reconstruct the evolution of amino acid

  1. Early Cretaceous greenhouse pumped higher taxa diversification in spiders.

    Shao, Lili; Li, Shuqiang

    2018-05-24

    The Cretaceous experienced one of the most remarkable greenhouse periods in geological history. During this time, ecosystem reorganizations significantly impacted the diversification of many groups of organisms. The rise of angiosperms marked a major biome turnover. Notwithstanding, relatively little remains known about how the Cretaceous global ecosystem impacted the evolution of spiders, which constitute one of the most abundant groups of predators. Herein, we evaluate the transcriptomes of 91 taxa representing more than half of the spider families. We add 23 newly sequenced taxa to the existing database to obtain a robust phylogenomic assessment. Phylogenetic reconstructions using different datasets and methods obtain novel placements of some groups, especially in the Synspermiata and the group having a retrolateral tibial apophysis (RTA). Molecular analyses indicate an expansion of the RTA clade at the Early Cretaceous with a hunting predatory strategy shift. Fossil analyses show a 7-fold increase of diversification rate at the same period, but this likely owes to the first occurrences spider in amber deposits. Additional analyses of fossil abundance show an accumulation of spider lineages in the Early Cretaceous. We speculate that the establishment of a warm greenhouse climate pumped the diversification of spiders, in particular among webless forms tracking the abundance of insect prey. Our study offers a new pathway for future investigations of spider phylogeny and diversification. Copyright © 2018. Published by Elsevier Inc.

  2. Impact of prescribed burning on a heathland inhabiting spider community

    Krause, Rolf Harald

    2016-04-01

    Full Text Available Heathlands can provide refuge for many stenotopic and endangered arthropods, if habitat management practices are applied. A management measure that is rarely being used today, but which has the potential to support diversity of arthropod communities, is prescribed burning. In this study we investigated the effects of prescribed burning on spider assemblages on a burned site with Calluna vulgaris in the nature reserve Lueneburg Heath, northwest Germany. We used pitfall trapping with a sampling design of 39 traps over a period of one year and 17 sampling intervals on a burned and a control site. We compared overall species richness, activity abundance patterns and community composition of the two sites, with a particular focus on stenotopic and endangered species. We collected 5116 adult spiders and 99 species altogether in a relatively small sampling area. This number of species represents nearly one third of the regional species pool of heathland spider species. Twelve species occurred exclusively on the burned site in contrast to 28 species exclusively found on the unburned site. Although we found more than twice as many spider individuals and higher mean species richness on the control site than on the burned site, the species richness of red-listed spiders was higher on the burned site. Especially the fact that we found 24 endangered species on the burned site and only 20 on the control site indicates that the applied measure of prescribed burning can foster certain endangered spider species and contribute to preserving the overall biodiversity of heathland ecosystems.

  3. Nutrient Deprivation Induces Property Variations in Spider Gluey Silk

    Blamires, Sean J.; Sahni, Vasav; Dhinojwala, Ali; Blackledge, Todd A.; Tso, I-Min

    2014-01-01

    Understanding the mechanisms facilitating property variability in biological adhesives may promote biomimetic innovations. Spider gluey silks such as the spiral threads in orb webs and the gumfoot threads in cobwebs, both of which comprise of an axial thread coated by glue, are biological adhesives that have variable physical and chemical properties. Studies show that the physical and chemical properties of orb web gluey threads change when spiders are deprived of food. It is, however, unknown whether gumfoot threads undergo similar property variations when under nutritional stress. Here we tested whether protein deprivation induces similar variations in spiral and gumfoot thread morphology and stickiness. We manipulated protein intake for the orb web spider Nephila clavipes and the cobweb spider Latrodectus hesperus and measured the diameter, glue droplet volume, number of droplets per mm, axial thread width, thread stickiness and adhesive energy of their gluey silks. We found that the gluey silks of both species were stickier when the spiders were deprived of protein than when the spiders were fed protein. In N. clavipes a concomitant increase in glue droplet volume was found. Load-extension curves showed that protein deprivation induced glue property variations independent of the axial thread extensions in both species. We predicted that changes in salt composition of the glues were primarily responsible for the changes in stickiness of the silks, although changes in axial thread properties might also contribute. We, additionally, showed that N. clavipes' glue changes color under protein deprivation, probably as a consequence of changes to its biochemical composition. PMID:24523902

  4. Phobic spider fear is associated with enhanced attentional capture by spider pictures: a rapid serial presentation event-related potential study.

    Van Strien, Jan W; Franken, Ingmar H A; Huijding, Jorg

    2009-03-04

    The early posterior negativity (EPN) reflects early selective visual processing of emotionally significant information. This study explored the association between fear of spiders and the EPN for spider pictures. Fifty women completed a Spider Phobia Questionnaire and watched the random rapid serial presentation of 600 neutral, 600 negatively valenced emotional, and 600 spider pictures (three pictures per second). The EPN was scored as the mean activity in the 225-300-ms time window at lateral occipital electrodes. Participants with higher scores on the phobia questionnaire showed larger (i.e. more negative) EPN amplitudes in response to spider pictures. The results suggest that the attentional capture of spider-related stimuli is an automatic response, which is modulated by the extent of spider fear.

  5. Atomistic model of the spider silk nanostructure

    Keten, Sinan; Buehler, Markus J.

    2010-04-01

    Spider silk is an ultrastrong and extensible self-assembling biopolymer that outperforms the mechanical characteristics of many synthetic materials including steel. Here we report atomic-level structures that represent aggregates of MaSp1 proteins from the N. Clavipes silk sequence based on a bottom-up computational approach using replica exchange molecular dynamics. We discover that poly-alanine regions predominantly form distinct and orderly beta-sheet crystal domains while disorderly structures are formed by poly-glycine repeats, resembling 31-helices. These could be the molecular source of the large semicrystalline fraction observed in silks, and also form the basis of the so-called "prestretched" molecular configuration. Our structures are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content.

  6. VDLLA: A virtual daddy-long legs optimization

    Yaakub, Abdul Razak; Ghathwan, Khalil I.

    2016-08-01

    Swarm intelligence is a strong optimization algorithm based on a biological behavior of insects or animals. The success of any optimization algorithm is depending on the balance between exploration and exploitation. In this paper, we present a new swarm intelligence algorithm, which is based on daddy long legs spider (VDLLA) as a new optimization algorithm with virtual behavior. In VDLLA, each agent (spider) has nine positions which represent the legs of spider and each position represent one solution. The proposed VDLLA is tested on four standard functions using average fitness, Medium fitness and standard deviation. The results of proposed VDLLA have been compared against Particle Swarm Optimization (PSO), Differential Evolution (DE) and Bat Inspired Algorithm (BA). Additionally, the T-Test has been conducted to show the significant deference between our proposed and other algorithms. VDLLA showed very promising results on benchmark test functions for unconstrained optimization problems and also significantly improved the original swarm algorithms.

  7. The phylogeny of fossil whip spiders.

    Garwood, Russell J; Dunlop, Jason A; Knecht, Brian J; Hegna, Thomas A

    2017-04-21

    Arachnids are a highly successful group of land-dwelling arthropods. They are major contributors to modern terrestrial ecosystems, and have a deep evolutionary history. Whip spiders (Arachnida, Amblypygi), are one of the smaller arachnid orders with ca. 190 living species. Here we restudy one of the oldest fossil representatives of the group, Graeophonus anglicus Pocock, 1911 from the Late Carboniferous (Duckmantian, ca. 315 Ma) British Middle Coal Measures of the West Midlands, UK. Using X-ray microtomography, our principal aim was to resolve details of the limbs and mouthparts which would allow us to test whether this fossil belongs in the extant, relict family Paracharontidae; represented today by a single, blind species Paracharon caecus Hansen, 1921. Tomography reveals several novel and significant character states for G. anglicus; most notably in the chelicerae, pedipalps and walking legs. These allowed it to be scored into a phylogenetic analysis together with the recently described Paracharonopsis cambayensis Engel & Grimaldi, 2014 from the Eocene (ca. 52 Ma) Cambay amber, and Kronocharon prendinii Engel & Grimaldi, 2014 from Cretaceous (ca. 99 Ma) Burmese amber. We recovered relationships of the form ((Graeophonus (Paracharonopsis + Paracharon)) + (Charinus (Stygophrynus (Kronocharon (Charon (Musicodamon + Paraphrynus)))))). This tree largely reflects Peter Weygoldt's 1996 classification with its basic split into Paleoamblypygi and Euamblypygi lineages; we were able to score several of his characters for the first time in fossils. Our analysis draws into question the monophyly of the family Charontidae. Our data suggest that Graeophonus is a crown group amblypygid, and falls within a monophyletic Paleoamblypgi clade, but outside the family Paracharontidae (= Paracharonopsis + Paracharon). Our results also suggest a new placement for the Burmese amber genus Kronocharon, a node further down from its original position. Overall, we offer a

  8. WE-AB-BRB-01: Development of a Probe-Format Graphite Calorimeter for Practical Clinical Dosimetry: Numerical Design Optimization, Prototyping, and Experimental Proof-Of-Concept

    Renaud, J; Seuntjens, J; Sarfehnia, A

    2015-01-01

    Purpose: In this work, the feasibility of performing absolute dose to water measurements using a constant temperature graphite probe calorimeter (GPC) in a clinical environment is established. Methods: A numerical design optimization study was conducted by simulating the heat transfer in the GPC resulting from irradiation using a finite element method software package. The choice of device shape, dimensions, and materials was made to minimize the heat loss in the sensitive volume of the GPC. The resulting design, which incorporates a novel aerogel-based thermal insulator, and 15 temperature sensitive resistors capable of both Joule heating and measuring temperature, was constructed in house. A software based process controller was developed to stabilize the temperatures of the GPC’s constituent graphite components to within a few 10’s of µK. This control system enables the GPC to operate in either the quasi-adiabatic or isothermal mode, two well-known, and independent calorimetry techniques. Absorbed dose to water measurements were made using these two methods under standard conditions in a 6 MV 1000 MU/min photon beam and subsequently compared against TG-51 derived values. Results: Compared to an expected dose to water of 76.9 cGy/100 MU, the average GPC-measured doses were 76.5 ± 0.5 and 76.9 ± 0.5 cGy/100 MU for the adiabatic and isothermal modes, respectively. The Monte Carlo calculated graphite to water dose conversion was 1.013, and the adiabatic heat loss correction was 1.003. With an overall uncertainty of about 1%, the most significant contributions were the specific heat capacity (type B, 0.8%) and the repeatability (type A, 0.6%). Conclusion: While the quasi-adiabatic mode of operation had been validated in previous work, this is the first time that the GPC has been successfully used isothermally. This proof-of-concept will serve as the basis for further study into the GPC’s application to small fields and MRI-linac dosimetry. This work has been

  9. Probe Storage

    Gemelli, Marcellino; Abelmann, Leon; Engelen, Johannes Bernardus Charles; Khatib, M.G.; Koelmans, W.W.; Zaboronski, Olog; Campardo, Giovanni; Tiziani, Federico; Laculo, Massimo

    2011-01-01

    This chapter gives an overview of probe-based data storage research over the last three decades, encompassing all aspects of a probe recording system. Following the division found in all mechanically addressed storage systems, the different subsystems (media, read/write heads, positioning, data

  10. Cultural probes

    Madsen, Jacob Østergaard

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  11. Riparian spiders as sentinels of PCB contamination across heterogeneous aquatic ecosystems

    Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the ...

  12. Research on Artificial Spider Web Model for Farmland Wireless Sensor Network

    Jun Wang; Song Gao; Shimin Zhao; Guang Hu; Xiaoli Zhang; Guowang Xie

    2018-01-01

    Through systematic analysis of the structural characteristics and invulnerability of spider web, this paper explores the possibility of combining the advantages of spider web such as network robustness and invulnerability with farmland wireless sensor network. A universally applicable definition and mathematical model of artificial spider web structure are established. The comparison between artificial spider web and traditional networks is discussed in detail. The simulation result shows tha...

  13. Science 101: Why Don't Spiders Stick to Their Own Webs?

    Robertson, Bill

    2011-01-01

    This article explains why spiders don't stick to their webs. Spiders don't get stuck in their own webs (and they aren't immune to their own glue) because they use a combination of sticky and nonsticky threads (different glands for producing those), and the glue is in droplets that the spider can avoid but the prey can't. The spider's nervous…

  14. Ineffective crypsis in a crab spider: a prey community perspective.

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2010-03-07

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts upon. We carried out a manipulative field experiment using a complete factorial design resulting in six different colour combinations of crab spiders and flowers differing in their degree of colour-matching. A rich and diverse set of naturally occurring insects visited the flowers while we continuously video-recorded the spider's foraging activity. This enabled us to test the crypsis, the spider avoidance and the flower visitor attraction hypotheses, all three supported by previous studies. Flower visitors of different groups either avoided crab spiders independent of colour-matching, such as solitary bees and syrphid flies, or ignored them, such as bumble-bees and honeybees. Moreover, colour-matched spiders did not have a higher encounter rate and capture success compared to the visually apparent ones. Thus, our results support the spider avoidance hypothesis, reject the two other hypotheses and uncovered a fourth behaviour: indifference to predators. Because flower visitors reacted differently, a community approach is mandatory in order to understand the function of background colour-matching in generalist predators. We discuss our results in relation to the size and sociality of the prey and in relation to the functional significance of colour change in this predator.

  15. Molecular Evolution of Spider Vision: New Opportunities, Familiar Players.

    Morehouse, Nathan I; Buschbeck, Elke K; Zurek, Daniel B; Steck, Mireille; Porter, Megan L

    2017-08-01

    Spiders are among the world's most species-rich animal lineages, and their visual systems are likewise highly diverse. These modular visual systems, composed of four pairs of image-forming "camera" eyes, have taken on a huge variety of forms, exhibiting variation in eye size, eye placement, image resolution, and field of view, as well as sensitivity to color, polarization, light levels, and motion cues. However, despite this conspicuous diversity, our understanding of the genetic underpinnings of these visual systems remains shallow. Here, we review the current literature, analyze publicly available transcriptomic data, and discuss hypotheses about the origins and development of spider eyes. Our efforts highlight that there are many new things to discover from spider eyes, and yet these opportunities are set against a backdrop of deep homology with other arthropod lineages. For example, many (but not all) of the genes that appear important for early eye development in spiders are familiar players known from the developmental networks of other model systems (e.g., Drosophila). Similarly, our analyses of opsins and related phototransduction genes suggest that spider photoreceptors employ many of the same genes and molecular mechanisms known from other arthropods, with a hypothesized ancestral spider set of four visual and four nonvisual opsins. This deep homology provides a number of useful footholds into new work on spider vision and the molecular basis of its extant variety. We therefore discuss what some of these first steps might be in the hopes of convincing others to join us in studying the vision of these fascinating creatures.

  16. First report of clinical presentation of a bite by a running spider ...

    This article describes the clinical progression of symptoms over a period of 5 days of a bite inflicted by a Philodromus sp. spider. Commonly known as 'running spiders', these are not considered to be harmful to humans. This report, however, is the first description of an actual bite by a member of this group of spiders ...

  17. Salticid predation as one potential driving force of ant mimicry in jumping spiders

    Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min

    2011-01-01

    Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods. PMID:20961898

  18. High School Students' Attitudes towards Spiders: A Cross-Cultural Comparison

    Prokop, Pavol; Tolarovicova, Andrea; Camerik, Anne M.; Peterkova, Viera

    2010-01-01

    Spiders are traditionally considered to be among the least popular of animals. Current evidence suggests that a negative attitude towards spiders could be influenced by both cultural and evolutionary pressures. Some researchers suggest that science education activities could positively influence students' perceptions of spiders. Their evidence is,…

  19. Mobile probes

    Ørngreen, Rikke; Jørgensen, Anna Neustrup; Noesgaard, Signe Schack

    2016-01-01

    A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....

  20. Optical probe

    Denis, J.; Decaudin, J.M.

    1984-01-01

    The probe includes optical means of refractive index n, refracting an incident light beam from a medium with a refractive index n1>n and reflecting an incident light beam from a medium with a refractive index n2 [fr

  1. Spider Silk as Guiding Biomaterial for Human Model Neurons

    Frank Roloff

    2014-01-01

    Full Text Available Over the last years, a number of therapeutic strategies have emerged to promote axonal regeneration. An attractive strategy is the implantation of biodegradable and nonimmunogenic artificial scaffolds into injured peripheral nerves. In previous studies, transplantation of decellularized veins filled with spider silk for bridging critical size nerve defects resulted in axonal regeneration and remyelination by invading endogenous Schwann cells. Detailed interaction of elongating neurons and the spider silk as guidance material is unknown. To visualize direct cellular interactions between spider silk and neurons in vitro, we developed an in vitro crossed silk fiber array. Here, we describe in detail for the first time that human (NT2 model neurons attach to silk scaffolds. Extending neurites can bridge gaps between single silk fibers and elongate afterwards on the neighboring fiber. Culturing human neurons on the silk arrays led to an increasing migration and adhesion of neuronal cell bodies to the spider silk fibers. Within three to four weeks, clustered somata and extending neurites formed ganglion-like cell structures. Microscopic imaging of human neurons on the crossed fiber arrays in vitro will allow for a more efficient development of methods to maximize cell adhesion and neurite growth on spider silk prior to transplantation studies.

  2. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A [Department of Tissue Regeneration, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands); Hedhammar, My; Johansson, Jan [Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, the Biomedical Centre, Box 575, 751 23 Uppsala (Sweden); Blom, Tobias; Leifer, Klaus [Department of Engineering Sciences, Uppsala University, Box 534, S-751 21 Uppsala (Sweden)

    2010-08-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  3. Biomimetic calcium phosphate coatings on recombinant spider silk fibres

    Yang Liang; Habibovic, Pamela; Van Blitterswijk, Clemens A; Hedhammar, My; Johansson, Jan; Blom, Tobias; Leifer, Klaus

    2010-01-01

    Calcium phosphate ceramic coatings, applied on surfaces of metallic and polymeric biomaterials, can improve their performance in bone repair and regeneration. Spider silk is biocompatible, strong and elastic, and hence an attractive biomaterial for applications in connective tissue repair. Recently, artificial spider silk, with mechanical and structural characteristics similar to those of native spider silk, has been produced from recombinant minispidroins. In the present study, supersaturated simulated body fluid was used to deposit calcium phosphate coatings on recombinant spider silk fibres. The mineralization process was followed in time using scanning electron microscopy equipped with an energy dispersive x-ray (EDX) detector and Raman spectroscope. Focused ion beam technology was used to produce a cross section of a coated fibre, which was further analysed by EDX. Preliminary in vitro experiments using a culture of bone marrow-derived human mesenchymal stem cells (hMSCs) on coated fibres were also performed. This study showed that recombinant spider silk fibres were successfully coated with a homogeneous and thick crystalline calcium phosphate layer. In the course of the mineralization process from modified simulated body fluid, sodium chloride crystals were first deposited on the silk surface, followed by the deposition of a calcium phosphate layer. The coated silk fibres supported the attachment and growth of hMSCs.

  4. Arachnid aloft: directed aerial descent in neotropical canopy spiders.

    Yanoviak, Stephen P; Munk, Yonatan; Dudley, Robert

    2015-09-06

    The behaviour of directed aerial descent has been described for numerous taxa of wingless hexapods as they fall from the tropical rainforest canopy, but is not known in other terrestrial arthropods. Here, we describe similar controlled aerial behaviours for large arboreal spiders in the genus Selenops (Selenopidae). We dropped 59 such spiders from either canopy platforms or tree crowns in Panama and Peru; the majority (93%) directed their aerial trajectories towards and then landed upon nearby tree trunks. Following initial dorsoventral righting when necessary, falling spiders oriented themselves and then translated head-first towards targets; directional changes were correlated with bilaterally asymmetric motions of the anterolaterally extended forelegs. Aerial performance (i.e. the glide index) decreased with increasing body mass and wing loading, but not with projected surface area of the spider. Along with the occurrence of directed aerial descent in ants, jumping bristletails, and other wingless hexapods, this discovery of targeted gliding in selenopid spiders further indicates strong selective pressures against uncontrolled falls into the understory for arboreal taxa. © 2015 The Author(s).

  5. Detection and phylogenetic analysis of bacteriophage WO in spiders (Araneae).

    Yan, Qian; Qiao, Huping; Gao, Jin; Yun, Yueli; Liu, Fengxiang; Peng, Yu

    2015-11-01

    Phage WO is a bacteriophage found in Wolbachia. Herein, we represent the first phylogenetic study of WOs that infect spiders (Araneae). Seven species of spiders (Araneus alternidens, Nephila clavata, Hylyphantes graminicola, Prosoponoides sinensis, Pholcus crypticolens, Coleosoma octomaculatum, and Nurscia albofasciata) from six families were infected by Wolbachia and WO, followed by comprehensive sequence analysis. Interestingly, WO could be only detected Wolbachia-infected spiders. The relative infection rates of those seven species of spiders were 75, 100, 88.9, 100, 62.5, 72.7, and 100 %, respectively. Our results indicated that both Wolbachia and WO were found in three different body parts of N. clavata, and WO could be passed to the next generation of H. graminicola by vertical transmission. There were three different sequences for WO infected in A. alternidens and two different WO sequences from C. octomaculatum. Only one sequence of WO was found for the other five species of spiders. The discovered sequence of WO ranged from 239 to 311 bp. Phylogenetic tree was generated using maximum likelihood (ML) based on the orf7 gene sequences. According to the phylogenetic tree, WOs in N. clavata and H. graminicola were clustered in the same group. WOs from A. alternidens (WAlt1) and C. octomaculatum (WOct2) were closely related to another clade, whereas WO in P. sinensis was classified as a sole cluster.

  6. Endemic harvestmen and spiders of Austria (Arachnida: Opiliones, Araneae

    Komposch, Christian

    2011-01-01

    Full Text Available A comprehensive overview of plant, fungus and animal species of Austria revealed a total of 748 endemic and subendemic species, including, 11 harvestman and 46 spider species. Altogether two endemic harvestmen (Nemastoma bidentatum relictum, Nemastoma schuelleri and 8 endemic spiders (Abacoproeces molestus, Collinsia (caliginosa nemenziana, Mughiphantes severus, Mughiphantes styriacus, Pelecopsis alpica, Scotophaeus nanus, Troglohyphantes novicordis, Troglohyphantes tauriscus, beside 9 subendemic harvestman and 38 subendemic spider species have been recorded from Austria. Hot-spots of endemism in the Eastern Alps are the north-eastern (Ennstaler Alps and southern Calcareous Alps (Karawanken, Karnische Alps and the Central Alps (Hohe Tauern, Gurktaler Alps, Ötztaler and Stubaier Alps. Most of the endemic arachnid species occur from the nival down to the montane zone. Important habitats are rocky areas, caves and woodlands. High absolute numbers and percentages of endemics can be found within the harvestman families Cladonychiidae, Ischyropsalididae and Nemastomatidae and in the spider genera Lepthyphantes s. l. and Troglohyphantes. The conservation status of these highly endangered taxa – 85 % of the spider species and 100 % of the harvestman taxa are endangered in Austria – is poor.

  7. Radiation Safety System for SPIDER Neutral Beam Accelerator

    Sandri, S.; Poggi, C.; Coniglio, A.; D'Arienzo, M.

    2011-01-01

    SPIDER (Source for Production of Ion of Deuterium Extracted from RF Plasma only) and MITICA (Megavolt ITER Injector Concept Advanced) are the ITER neutral beam injector (NBI) testing facilities of the PRIMA (Padova Research Injector Megavolt Accelerated) Center. Both injectors accelerate negative deuterium ions with a maximum energy of 1 MeV for MITICA and 100 keV for SPIDER with a maximum beam current of 40 A for both experiments. The SPIDER facility is classified in Italy as a particle accelerator. At present, the design of the radiation safety system for the facility has been completed and the relevant reports have been presented to the Italian regulatory authorities. Before SPIDER can operate, approval must be obtained from the Italian Regulatory Authority Board (IRAB) following a detailed licensing process. In the present work, the main project information and criteria for the SPIDER injector source are reported together with the analysis of hypothetical accidental situations and safety issues considerations. Neutron and photon nuclear analysis is presented, along with special shielding solutions designed to meet Italian regulatory dose limits. The contribution of activated corrosion products (ACP) to external exposure of workers has also been assessed. Nuclear analysis indicates that the photon contribution to worker external exposure is negligible, and the neutron dose can be considered by far the main radiation protection issue. Our results confirm that the injector has no important radiological impact on the population living around the facility.

  8. Counting probe

    Matsumoto, Haruya; Kaya, Nobuyuki; Yuasa, Kazuhiro; Hayashi, Tomoaki

    1976-01-01

    Electron counting method has been devised and experimented for the purpose of measuring electron temperature and density, the most fundamental quantities to represent plasma conditions. Electron counting is a method to count the electrons in plasma directly by equipping a probe with the secondary electron multiplier. It has three advantages of adjustable sensitivity, high sensitivity of the secondary electron multiplier, and directional property. Sensitivity adjustment is performed by changing the size of collecting hole (pin hole) on the incident front of the multiplier. The probe is usable as a direct reading thermometer of electron temperature because it requires to collect very small amount of electrons, thus it doesn't disturb the surrounding plasma, and the narrow sweep width of the probe voltage is enough. Therefore it can measure anisotropy more sensitively than a Langmuir probe, and it can be used for very low density plasma. Though many problems remain on anisotropy, computer simulation has been carried out. Also it is planned to provide a Helmholtz coil in the vacuum chamber to eliminate the effect of earth magnetic field. In practical experiments, the measurement with a Langmuir probe and an emission probe mounted to the movable structure, the comparison with the results obtained in reverse magnetic field by using a Helmholtz coil, and the measurement of ionic sound wave are scheduled. (Wakatsuki, Y.)

  9. Effects of attention manipulations on motivated attention to feared and nonfeared negative distracters in spider fear.

    Norberg, Joakim; Wiens, Stefan

    2013-11-09

    When people view emotional and neutral pictures, the emotional pictures capture more attention than do neutral pictures. In support, studies with event-related potentials have shown that the early posterior negativity (EPN) and the late positive potential (LPP) to emotional versus neutral pictures are enhanced when pictures are attended. However, this motivated attention decreases when voluntary attention is directed away from the pictures. Most previous studies included only generally emotional pictures of either negative or positive valence. Because people with spider fear report intense fear of spiders, we examined whether directing attention away from emotional pictures at fixation decreases motivated attention less strongly for spiders than for generally negative distracters. We recorded event-related potentials from 128 channels to study whether manipulations of attention (i.e., spatial attention and perceptual load) decrease the EPN and the LPP to emotional distracters less strongly for spiders than for fear-irrelevant negative pictures in people with spider fear. Results confirmed that the EPN and the LPP to spiders (vs. neutral pictures) were particularly enhanced in participants with spider fear compared to participants without spider fear. When attention was directed away from the pictures, the EPN and the LPP to spiders (vs. neutral pictures) decreased similarly in fearful and nonfearful participants. Further, in fearful participants, the decrease in the EPN and the LPP was similar for spiders and for fear-irrelevant negative pictures. Our findings suggest that for people with spider fear, directing attention away from emotional pictures at fixation decreases motivated attention to these distracters similarly for spiders as for fear-irrelevant negative pictures. These findings imply that attention to spiders in spider fear does not exceed the level of attention expected from the spider pictures' high arousal and negative valence (i.e., their intrinsic

  10. Subsocial behaviour and brood adoption in mixed-species colonies of two theridiid spiders

    Grinsted, Lena; Agnarsson, Ingi; Bilde, Trine

    2012-01-01

    Cooperation and group living often evolves through kin selection. However, associations between unrelated organisms, such as different species, can evolve if both parties benefit from the interaction. Group living is rare in spiders, but occurs in cooperative, permanently social spiders, as well...... as in territorial, colonial spiders. Mixed species spider colonies, involving closely related species, have rarely been documented. We examined social interactions in newly discovered mixed-species colonies of theridiid spiders on Bali, Indonesia. Our aim was to test the degree of intra- and interspecific tolerance...

  11. Influence of spider silk on refugia preferences of the recluse spiders Loxosceles reclusa and Loxosceles laeta (Araneae: Sicariidae).

    Vetter, Richard S; Rust, Michael K

    2010-06-01

    In a previous experimental study, recluse spiders Loxosceles reclusa Gertsch and Mulaik and Loxosceles laeta (Nicolet) (Araneae: Sicariidae) preferred small cardboard refugia covered with conspecific silk compared with never-occupied refugia. Herein, we investigated some factors that might be responsible for this preference using similar cardboard refugia. When the two Loxosceles species were given choices between refugia previously occupied by their own and by the congeneric species, neither showed a species-specific preference; however, each chose refugia coated with conspecific silk rather than those previously inhabited by a distantly related cribellate spider, Metaltella simoni (Keyserling). When L. laeta spiders were offered refugia that were freshly removed from silk donors compared with heated, aged refugia from the same silk donor, older refugia were preferred. Solvent extracts of L. laeta silk were chosen approximately as often as control refugia when a range of solvents (methylene chloride:methanol, water, and hexane) were used. However, when acetone was used on similar silk, there was a statistical preference for the control, indicating that there might be a mildly repellent aspect to acetone-washed silk. Considering the inability to show attraction to chemical aspects of fresh silk, it seems that physical attributes may be more important for selection and that there might be repellency to silk of a recently vacated spider. These findings are discussed in regard to pest management strategies to control recluse spiders.

  12. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders.

    Gan, Wenjin; Liu, Shengjie; Yang, Xiaodong; Li, Daiqin; Lei, Chaoliang

    2015-09-24

    A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders. © 2015. Published by The Company of Biologists Ltd.

  13. Prey interception drives web invasion and spider size determines successful web takeover in nocturnal orb-web spiders

    Wenjin Gan

    2015-10-01

    Full Text Available A striking feature of web-building spiders is the use of silk to make webs, mainly for prey capture. However, building a web is energetically expensive and increases the risk of predation. To reduce such costs and still have access to abundant prey, some web-building spiders have evolved web invasion behaviour. In general, no consistent patterns of web invasion have emerged and the factors determining web invasion remain largely unexplored. Here we report web invasion among conspecifics in seven nocturnal species of orb-web spiders, and examined the factors determining the probability of webs that could be invaded and taken over by conspecifics. About 36% of webs were invaded by conspecifics, and 25% of invaded webs were taken over by the invaders. A web that was built higher and intercepted more prey was more likely to be invaded. Once a web was invaded, the smaller the size of the resident spider, the more likely its web would be taken over by the invader. This study suggests that web invasion, as a possible way of reducing costs, may be widespread in nocturnal orb-web spiders.

  14. Improvements of the magnetic field design for SPIDER and MITICA negative ion beam sources

    Chitarin, G.; Agostinetti, P.; Aprile, D.; Marconato, N.; Veltri, P.

    2015-01-01

    The design of the magnetic field configuration in the SPIDER and MITICA negative ion beam sources has evolved considerably during the past four years. This evolution was driven by three factors: 1) the experimental results of the large RF-driven ion sources at IPP, which have provided valuable indications on the optimal magnetic configurations for reliable RF plasma source operation and for large negative ion current extraction, 2) the comprehensive beam optics and heat load simulations, which showed that the magnetic field configuration in the accelerator is crucial for keeping the heat load due to electrons on the accelerator grids within tolerable limits, without compromising the optics of the negative ion beam in the foreseen operating scenarios, 3) the progress of the detailed mechanical design of the accelerator, which stimulated the evaluation of different solutions for the correction of beamlet deflections of various origin and for beamlet aiming. On this basis, new requirements and solution concepts for the magnetic field configuration in the SPIDER and MITICA beam sources have been progressively introduced and updated until the design converged. The paper presents how these concepts have been integrated into a final design solution based on a horizontal “long-range” field (few mT) in combination with a “local” vertical field of some tens of mT on the acceleration grids

  15. Multivariable control of a rolling spider drone

    Lyu, Haifeng

    The research and application of Unmanned Aerial Vehicles (UAVs) has been a hot topic recently. A UAV is dened as an aircraft which is designed not to carry a human pilot or operated with remote electronic input by the flight controller. In this thesis, the design of a control system for a quadcopter named Rolling Spider Drone is conducted. The thesis work presents the design of two kinds of controllers that can control the Drone to keep it balanced and track different kinds of input trajectories. The nonlinear mathematical model for the Drone is derived by the Newton-Euler method. The rotational subsystem and translational system are derived to describe the attitude and position motion of Drone. Techniques from linear control theory are employed to linearize the highly coupled and nonlinear quadcopter plant around equilibrium points and apply the linear feedback controller to stabilize the system. The controller is a digital tracking system that deploys LQR for system stability design. Fixed gain and adaptive gain scheduled controllers are developed and compared with different LQR weights. Step references and reference trajectories involving signicant variation for the yaw angle in the xy-plane and three-dimensional spaces are tracked in the simulation. The physical implementation and an output feedback controller are considered for future work.

  16. Recombinant Spider Silks—Biopolymers with Potential for Future Applications

    Thomas Scheibel

    2011-03-01

    Full Text Available Nature has evolved a range of materials that compete with man-made materials in physical properties; one of these is spider silk. Silk is a fibrous material that exhibits extremely high strength and toughness with regard to its low density. In this review we discuss the molecular structure of spider silk and how this understanding has allowed the development of recombinant silk proteins that mimic the properties of natural spider silks. Additionally, we will explore the material morphologies and the applications of these proteins. Finally, we will look at attempts to combine the silk structure with chemical polymers and how the structure of silk has inspired the engineering of novel polymers.

  17. Synthetic Adhesive Attachment Discs based on Spider Pyriform Silk Architecture

    Jain, Dharamdeep; Sahni, Vasav; Dhinojwala, Ali

    2014-03-01

    Among the variety of silks produced by spiders, pyriform silk is used in conjunction with the dragline silk to attach webs to different surfaces. Cob weaver spiders employ different architectural patterns to utilize the pyriform silk and form attachment joints with each pattern having a characteristic adhesive performance. The staple pin architecture is a one of the strongest attachment designs employed by spiders to attach their webs. Here we use a synthetic approach to create the a similar patterned architecture attachment discs on aluminum substrate using thermoplastic polyurethane. Measurable pull off forces are generated when the synthetic discs are peeled off a surface. This innovative adhesive strategy can be a source of design in various biomedical applications. Financial Support from National Science Foundation.

  18. DNA probes

    Castelino, J.

    1992-01-01

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with 32 P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism's genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens

  19. DNA probes

    Castelino, J

    1993-12-31

    The creation of DNA probes for detection of specific nucleotide segments differs from ligand detection in that it is a chemical rather than an immunological reaction. Complementary DNA or RNA is used in place of the antibody and is labelled with {sup 32}P. So far, DNA probes have been successfully employed in the diagnosis of inherited disorders, infectious diseases, and for identification of human oncogenes. The latest approach to the diagnosis of communicable and parasitic infections is based on the use of deoxyribonucleic acid (DNA) probes. The genetic information of all cells is encoded by DNA and DNA probe approach to identification of pathogens is unique because the focus of the method is the nucleic acid content of the organism rather than the products that the nucleic acid encodes. Since every properly classified species has some unique nucleotide sequences that distinguish it from every other species, each organism`s genetic composition is in essence a finger print that can be used for its identification. In addition to this specificity, DNA probes offer other advantages in that pathogens may be identified directly in clinical specimens 10 figs, 2 tabs

  20. An image filtering technique for SPIDER visible tomography

    Fonnesu, N., E-mail: nicola.fonnesu@igi.cnr.it; Agostini, M.; Brombin, M.; Pasqualotto, R.; Serianni, G. [Consorzio RFX, Associazione EURATOM-ENEA sulla Fusione, Corso Stati Uniti 4, I-35127 Padova (Italy)

    2014-02-15

    The tomographic diagnostic developed for the beam generated in the SPIDER facility (100 keV, 50 A prototype negative ion source of ITER neutral beam injector) will characterize the two-dimensional particle density distribution of the beam. The simulations described in the paper show that instrumental noise has a large influence on the maximum achievable resolution of the diagnostic. To reduce its impact on beam pattern reconstruction, a filtering technique has been adapted and implemented in the tomography code. This technique is applied to the simulated tomographic reconstruction of the SPIDER beam, and the main results are reported.

  1. An image filtering technique for SPIDER visible tomography

    Fonnesu, N.; Agostini, M.; Brombin, M.; Pasqualotto, R.; Serianni, G.

    2014-01-01

    The tomographic diagnostic developed for the beam generated in the SPIDER facility (100 keV, 50 A prototype negative ion source of ITER neutral beam injector) will characterize the two-dimensional particle density distribution of the beam. The simulations described in the paper show that instrumental noise has a large influence on the maximum achievable resolution of the diagnostic. To reduce its impact on beam pattern reconstruction, a filtering technique has been adapted and implemented in the tomography code. This technique is applied to the simulated tomographic reconstruction of the SPIDER beam, and the main results are reported

  2. Synthesis and inhibition of N-alkyl-2-(4-hydroxybut-2-ynyl) pyridinium bromide for mild steel in acid solution: Box–Behnken design optimization and mechanism probe

    Gu, Tianbin; Chen, Zhengjun; Jiang, Xiaohui; Zhou, Limei; Liao, Yunwen; Duan, Ming; Wang, Hu; Pu, Qiang

    2015-01-01

    Highlights: • N-alkyl-2-(4-hydroxybut-2-ynyl) pyridinium bromide prepared is new type of inhibitor. • Box–Behnken experiment design-based optimization model is used to maximize inhibition efficiency. • O-n adsorbing on X70 steel surface enhances the resistance of the steel to acid corrosion. • O-n acts as mix-type inhibitor to suppress both the anodic and cathodic reaction of X70 steel. - Abstract: N-alkyl-2-(4-hydroxybut-2-ynyl) pyridinium bromides (designated as O-n) was synthesized and characterized by 1 H and 13 C NMR and FTIR. Box–Behnken design (BBD)-based optimization was engaged to analyze the factors and the interaction of the factors that influence the corrosion inhibition efficiency of O-n for X70 steel. The inhibition mechanism was also probed by means of X-ray photoelectron spectroscopy (XPS), Tafel polarization and electrochemical impedance spectroscopy (EIS) techniques

  3. When beauty is only skin deep; optimizing the sensitivity of specular neutron reflectivity for probing structure beneath the surface of thin filmsa)

    Majkrzak, Charles F.; Carpenter, Elisabeth; Heinrich, Frank; Berk, Norman F.

    2011-11-01

    Specular neutron reflectometry has become an established probe of the nanometer scale structure of materials in thin film and multilayered form. It has contributed especially to our understanding of soft condensed matter of interest in polymer science, organic chemistry, and biology and of magnetic hard condensed matter systems. In this paper we examine a number of key factors which have emerged that can limit the sensitivity of neutron reflection as such a probe. Among these is loss of phase information, and we discuss how knowledge about material surrounding a film of interest can be applied to help resolve the problem. In this context we also consider what role the quantum phenomenon of interaction-free measurement might play in enhancing the statistical efficiency for obtaining reflectivity or transmission data.

  4. Volatile compounds from leaves of the African spider plant (Gynandropsis gynandra) with bioactivity against spider mite (Tetranychus urticae)

    Nyalala, Samuel Odeyo; Petersen, Mikael Agerlin; Grout, Brian William Wilson

    2013-01-01

    Previous studies have demonstrated that Gynandropsis gynandra emits acetonitrile as a foliar volatile from intact plants and isolated leaves, and that this compound is an effective spider mite repellent. This study has used gas chromatography–mass spectrometry to investigate volatile compounds...... emitted from homogenised G. gynandra leaves to evaluate their tissue acetonitrile content and to look for other compounds that might be exploited for the management of spider mites. Acetonitrile was absent from the homogenised tissues of five lines of G. gynandra, studied over two seasons. Thirteen...... volatile compounds were emitted by G. gynandra at significantly higher levels than mite-susceptible pot roses, including isothiocyanates, aldehydes, esters, alcohols and terpenes. Six representative compounds were selected to assess bioactivity. Spider mite populations were completely inactive after a 2¿h...

  5. Innovation and optimization of a method of pump-probe polarimetry with pulsed laser beams in view of a precise measurement of parity violation in atomic cesium

    Chauvat, D.

    1997-10-01

    While Parity Violation (PV) experiments on highly forbidden transitions have been using detection of fluorescence signals; our experiment uses a pump-probe scheme to detect the PV signal directly on a transmitted probe beam. A pulsed laser beam of linear polarisation ε 1 excites the atoms on the 6S-7S cesium transition in a colinear electric field E || k(ex). The probe beam (k(pr) || k(ex)) of linear polarisation ε 2 tuned to the transition 7S-6P(3/2) is amplified. The small asymmetry (∼ 10 -6 ) in the gain that depends on the handedness of the tri-hedron (E, ε 1 , ε 2 ) is the manifestation of the PV effect. This is measured as an E-odd apparent rotation of the plane of polarization of the probe beam; using balanced mode polarimetry. New criteria of selection have been devised, that allow us to distinguish the true PV-signal against fake rotations due to electromagnetic interferences, geometrical effects, polarization imperfections, or stray transverse electric and magnetic fields. These selection criteria exploit the symmetry of the PV-rotation - linear dichroism - and the revolution symmetry of the experiment. Using these criteria it is not only possible to reject fake signals, but also to elucidate the underlying physical mechanisms and to measure the relevant defects of the apparatus. The present signal-to-noise ratio allows embarking in PV measurements to reach the 10% statistical accuracy. A 1% measurement still requires improvements. Two methods have been demonstrated. The first one exploits the amplification of the asymmetry at high gain - one major advantage provided by our detection method based on stimulated emission. The second method uses both a much higher incident intensity and a special dichroic component which magnifies tiny polarization rotations. (author)

  6. Conductivity Probe

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  7. Probe specificity

    Laget, J.M.

    1986-11-01

    Specificity and complementarity of hadron and electron probes must be systematically developed to answer three questions currently asked in intermediate energy nuclear physics: what is nucleus structure at short distances, what is nature of short range correlations, what is three body force nature [fr

  8. Manufacturing of the full size prototype of the ion source for the ITER neutral beam injector – The SPIDER beam source

    Pavei, Mauro, E-mail: mauro.pavei@igi.cnr.it [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy); Boilson, Deirdre [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Bonicelli, Tullio [Fusion for Energy, C/Joseph Pla 2, 08019 Barcelona (Spain); Boury, Jacques [Thales Electron Devices, Velizy Villacoublay (France); Bush, Michael [Galvano-T GmbH, T, Raiffeisenstraße 8, 51570 Windeck (Germany); Ceracchi, Andrea; Faso, Diego [CECOM S.r.l., Via Tiburtina – Guidonia Montecelio, Roma (Italy); Graceffa, Joseph [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Heinemann, Bernd [Max-Planck-Institut für Plasmaphysik, D-85740 Garching (Germany); Hemsworth, Ronald [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Lievin, Christophe [Thales Electron Devices, Velizy Villacoublay (France); Marcuzzi, Diego [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy); Masiello, Antonio [Fusion for Energy, C/Joseph Pla 2, 08019 Barcelona (Spain); Sczepaniak, Bernd [Galvano-T GmbH, T, Raiffeisenstraße 8, 51570 Windeck (Germany); Singh, Mahendrajit [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Toigo, Vanni; Zaccaria, Pierluigi [Consorzio RFX, C.so Stati Uniti 4, I-35127, Padova (Italy)

    2015-10-15

    Highlights: • Negative ion sources are key components of neutral beam injectors for nuclear fusion. • The SPIDER experiment aims to optimize the negative ion source of MITICA and HNB. • The SPIDER Beam Source manufacturing is currently on-going. • Manufacturing and assembling technological issues encountered are presented. - Abstract: In ITER, each heating neutral beam injector (HNB) will deliver about 16.5 MW heating power by accelerating a 40 A deuterium negative ion beam up to the energy of 1 MeV. The ions are generated inside a caesiated negative ion source, where the injected H{sub 2}/D{sub 2} is ionized by a radio frequency electromagnetic field. The SPIDER test bed, currently being manufactured, is going to be the ion source test facility for the full size ion source of the HNBs and of the diagnostic neutral beam injector of ITER. The SPIDER beam source comprises an ion source with 8 radio-frequency drivers and a three-grid system, providing an overall acceleration up to energies of about 100 keV [1]. SPIDER represents a substantial step forward between the half ITER size ion source, which is currently being tested at the ELISE test bed in IPP-Garching, and the negative ion sources to be used on ITER, in terms of layout, dimensions and operating parameters. The SPIDER beam source will be housed inside a vacuum vessel which will be equipped with a beam dump and a graphite diagnostic calorimeter. The manufacturing design of the main parts of the SPIDER beam source has been completed and many of the tests on the prototypes have been successfully passed. The most complex parts, from the manufacturing point of view, of the ion source and the accelerator, developed by galvanic deposition of copper are being manufactured. The manufacturing phase will be completed within 2015, when the assembly of the device will start at the PRIMA site, in Padova (I). The paper describes the status of the procurement, the adaptations operated on the design of the beam

  9. variability in condensed tannins and bitterness in spider plant ...

    ACSS

    Spider plant (Cleome gynandra L.) contributes considerably to the nutrition and medicines of communities in southern Africa. However, its utilisation is limited by its bitterness caused by condensed tannins. Unfortunately, processing options that reduce the bitterness also remove nutritionally and medicinally useful ...

  10. Crab spiders (Araeneae: Philodromidae, Thomisidae) of Ramsey County, Minnesota.

    Daniel. T. Jennings; Bruce Cutler

    1996-01-01

    Crab spiders of 2 families, 10 genera, and 35 species were collected over a 31-year period in Ramsey County, Minnesota. Rarely collected species included Philodromus keyserlingi, Xysticus pellax, X. chippewa, X. banksi and X. alboniger. Identification source(s), season and collection frequency, and biology are summarized for each species.

  11. Biological control of fruit-tree red spider mite

    Rabbinge, R.

    1976-01-01

    During the last decade, integrated pest control systems have been developed for several crops. One of the main fields of research in integrated control has been the control of orchard pests. Experience with modified spraying programmes in apple orchards, the increasing resistance of spider

  12. Inactivation of complement by Loxosceles reclusa spider venom.

    Gebel, H M; Finke, J H; Elgert, K D; Cambell, B J; Barrett, J T

    1979-07-01

    Zymosan depletion of serum complement in guinea pigs rendered them highly resistant to lesion by Loxosceles reclusa spider venom. Guinea pigs deficient in C4 of the complement system are as sensitive to the venom as normal guinea pigs. The injection of 35 micrograms of whole recluse venom intradermally into guinea pigs lowered their complement level by 35.7%. Brown recluse spider venom in concentrations as slight as 0.02 micrograms protein/ml can totally inactivate one CH50 of guinea pig complement in vitro. Bee, scorpion, and other spider venoms had no influence on the hemolytic titer of complement. Fractionation of recluse spider venom by Sephadex G-200 filtration separated the complement-inactivating property of the venom into three major regions which could be distinguished on the basis of heat stability as well as size. None was neutralized by antivenom. Polyacrylamide gel electrophoresis of venom resolved the complement inactivators into five fractions. Complement inactivated by whole venom or the Sephadex fractions could be restored to hemolytic activity by supplements of fresh serum but not by heat-inactivated serum, pure C3, pure C5, or C3 and C5 in combination.

  13. Effects of Packaging and Storage Conditions on Quality of Spider ...

    African Journal of Food, Agriculture, Nutrition and Development ... However, quality of spider plant seed is affected by one or more factors that cause negative ... The purpose of this research was to increase insight into how the seed quality of ...

  14. Biotechnological Trends in Spider and Scorpion Antivenom Development

    Laustsen, Andreas Hougaard; Solà, Mireia; Jappe, Emma Christine

    2016-01-01

    Spiders and scorpions are notorious for their fearful dispositions and their ability to inject venom into prey and predators, causing symptoms such as necrosis, paralysis, and excruciating pain. Information on venom composition and the toxins present in these species is growing due to an interest...

  15. Spiders (Araneae) as polyphagous natural enemies in orchards

    Bogya, S.

    1999-01-01

    Spiders (Araneae) occur in high abundance in all terrestrial ecosystems including agro-ecosystems. They are a very heterogeneous group of animals with different hunting tactics and therefore they play very different ecological roles. At family level these tactics are rather similar thus

  16. Competition between introduced and native spiders (Araneae: Linyphiidae)

    Houser, J.D.; Ginsberg, Howard S.; Jakob, Elizabeth M.

    2014-01-01

    The European sheet-web spider Linyphia triangularis (Araneae: Linyphiidae) has become established in Maine, where it often reaches very high densities. Two lines of evidence from previous work suggest that L. triangularis affects populations of the native linyphiid spider Frontinella communis. First, F. communis individuals are relatively scarce in both forest and coastal habitat where L. triangularis is common, but more common where L. triangularis is at low density. Second, in field experiments, F. communis species are less likely to settle in experimental plots when L. triangularis is present, and F. communis disappears from study plots when L. triangularis is introduced. Here we test two mechanisms that may underlie these patterns. First, we tested whether L. triangularis invades and usurps the webs of F. communis. When spiders were released onto webs of heterospecifics, L. triangularis was more likely to take over or share webs of F. communis than the reverse. We also observed natural takeovers of F. communis webs. Second, we explored the hypothesis that L. triangularis reduces prey availability for native species. We sampled flying prey in areas with L. triangularis and those where it had been removed, and found no effect of spider presence on measured prey density. We also found no effect of prey supplementation on web tenacity in F. communis, suggesting that F. communis movements are not highly dependent on prey availability. We conclude that web takeover is likely more important than prey reduction in driving negative effects of L. triangularis on F. communis.

  17. Determination of PCDDs in spider webs: preliminary studies

    Rybak, Justyna; Rutkowski, Radosław

    2018-01-01

    The application of spider webs for determination of polichlorinated dibenzo-para-dioxins (PCDDs) has been studied for the first time. The aim of the studies was to find out if spider webs are suitable for such examinations as it was proved in the previous research they are excellent indicators of air pollutants. Spiders are ubiquitous, thus collection of samples is easy and non-invasive. Studies were conducted within the city of Wrocław and surroundings, one of the biggest and at the same time heaviest polluted city in Poland. Five research sites have been chosen, where spider webs were collected after 60 days of continuous exposure time. Webs belonging to two genera Tegenaria sylvestris and Tegenaria ferruginea (family Agelenidae) have been chosen as they are large and very dense, thus they are very suitable for such examinations. Webs were found to retain dioxins probably mainly by external exposure. These promising results should be continued and expanded in the future research.

  18. The ITER Neutral Beam Test Facility towards SPIDER operation

    Toigo, V.; Dal Bello, S.; Gaio, E.; Luchetta, A.; Pasqualotto, R.; Zaccaria, P.; Bigi, M.; Chitarin, G.; Marcuzzi, D.; Pomaro, N.; Serianni, G.; Agostinetti, P.; Agostini, M.; Antoni, V.; Aprile, D.; Baltador, C.; Barbisan, M.; Battistella, M.; Boldrin, M.; Brombin, M.; Dalla Palma, M.; De Lorenzi, A.; Delogu, R.; De Muri, M.; Fellin, F.; Ferro, A.; Gambetta, G.; Grando, L.; Jain, P.; Maistrello, A.; Manduchi, G.; Marconato, N.; Pavei, M.; Peruzzo, S.; Pilan, N.; Pimazzoni, A.; Piovan, R.; Recchia, M.; Rizzolo, A.; Sartori, E.; Siragusa, M.; Spada, E.; Spagnolo, S.; Spolaore, M.; Taliercio, C.; Valente, M.; Veltri, P.; Zamengo, A.; Zaniol, B.; Zanotto, L.; Zaupa, M.; Boilson, D.; Graceffa, J.; Svensson, L.; Schunke, B.; Decamps, H.; Urbani, M.; Kushwah, M.; Chareyre, J.; Singh, M.; Bonicelli, T.; Agarici, G.; Garbuglia, A.; Masiello, A.; Paolucci, F.; Simon, M.; Bailly-Maitre, L.; Bragulat, E.; Gomez, G.; Gutierrez, D.; Mico, G.; Moreno, J.-F.; Pilard, V.; Chakraborty, A.; Baruah, U.; Rotti, C.; Patel, H.; Nagaraju, M. V.; Singh, N. P.; Patel, A.; Dhola, H.; Raval, B.; Fantz, U.; Fröschle, M.; Heinemann, B.; Kraus, W.; Nocentini, R.; Riedl, R.; Schiesko, L.; Wimmer, C.; Wünderlich, D.; Cavenago, M.; Croci, G.; Gorini, G.; Rebai, M.; Muraro, A.; Tardocchi, M.; Hemsworth, R.

    2017-08-01

    SPIDER is one of two projects of the ITER Neutral Beam Test Facility under construction in Padova, Italy, at the Consorzio RFX premises. It will have a 100 keV beam source with a full-size prototype of the radiofrequency ion source for the ITER neutral beam injector (NBI) and also, similar to the ITER diagnostic neutral beam, it is designed to operate with a pulse length of up to 3600 s, featuring an ITER-like magnetic filter field configuration (for high extraction of negative ions) and caesium oven (for high production of negative ions) layout as well as a wide set of diagnostics. These features will allow a reproduction of the ion source operation in ITER, which cannot be done in any other existing test facility. SPIDER realization is well advanced and the first operation is expected at the beginning of 2018, with the mission of achieving the ITER heating and diagnostic NBI ion source requirements and of improving its performance in terms of reliability and availability. This paper mainly focuses on the preparation of the first SPIDER operations—integration and testing of SPIDER components, completion and implementation of diagnostics and control and formulation of operation and research plan, based on a staged strategy.

  19. Remote monitoring of vibrational information in spider webs

    Mortimer, B.; Soler, A.; Siviour, C. R.; Vollrath, F.

    2018-06-01

    Spiders are fascinating model species to study information-acquisition strategies, with the web acting as an extension of the animal's body. Here, we compare the strategies of two orb-weaving spiders that acquire information through vibrations transmitted and filtered in the web. Whereas Araneus diadematus monitors web vibration directly on the web, Zygiella x-notata uses a signal thread to remotely monitor web vibration from a retreat, which gives added protection. We assess the implications of these two information-acquisition strategies on the quality of vibration information transfer, using laser Doppler vibrometry to measure vibrations of real webs and finite element analysis in computer models of webs. We observed that the signal thread imposed no biologically relevant time penalty for vibration propagation. However, loss of energy (attenuation) was a cost associated with remote monitoring via a signal thread. The findings have implications for the biological use of vibrations by spiders, including the mechanisms to locate and discriminate between vibration sources. We show that orb-weaver spiders are fascinating examples of organisms that modify their physical environment to shape their information-acquisition strategy.

  20. Multiple origins of subsociality in crab spiders (Thomisidae).

    Ruch, Jasmin; Riehl, Torben; May-Collado, Laura J; Agnarsson, Ingi

    2015-01-01

    Determining factors that facilitate the transition from a solitary to a social lifestyle is a major challenge in evolutionary biology, especially in taxa that are usually aggressive towards conspecifics. Most spiders live solitarily and few species are known to be social. Nevertheless, sociality has evolved multiple times across several families and nearly all studied social lineages have originated from a periodically social (subsocial) ancestor. Group-living crab spiders (Thomisidae) are exclusively found in Australia and differ from most other social spiders because they lack a communal capture web. Three of the group-living species were placed in the genus Diaea and another in the genus Xysticus. Most Australian thomisids are, however, difficult to identify as most descriptions are old and of poor quality, and the genera Diaea and Xysticus may not correspond to monophyletic groups. Here, we clarify the phylogenetic relationships of the four group-living Australian thomisids and conclude that amongst these subsociality has evolved two to three times independently. The subsocial Xysticus bimaculatus is not closely related to any of the social Diaea and an independent origin of subsociality is likely in this case. The presented data indicates that within Diaea two origins of subsociality are possible. Our results help to understand the evolution of sociality in thomisids and support the hypothesis that permanent sociality in spiders has evolved multiple times relatively recently from subsocial ancestors. Copyright © 2014 Elsevier Inc. All rights reserved.

  1. Preservice Teachers' Conceptions about Animals and Particularly about Spiders

    Jambrina, Carmen Urones; Vacas, Jose Manuel; Sanchez-Barbudo, Miguel

    2010-01-01

    Introduction: This article explores the scientific ideas and alternative conceptions that pre-service teachers have regarding animal classification and spiders in particular. Method: The study involved 40 pre-service teachers of elementary education in Spain and the data was collected by means of questionnaires, descriptions and drawings. The…

  2. Untangling the web...spiders in Arizona fields

    Many kinds of arthropod natural enemies (predators and parasitoids) inhabit crop fields in Arizona and can have a large negative impact on several pest insect species that also infest these crops. Many different species of spiders are common in cotton, alfalfa and other crops in Arizona. Among the ...

  3. The sejugal furrow in camel spiders and acariform mites

    Dunlop, Jason A.

    2012-07-01

    Full Text Available Camel spiders (Arachnida: Solifugae are one of the arachnid groups characterised by a prosomal dorsal shield composed of three distinct elements: the pro-, meso- and metapeltidium. These are associated respectively with prosomal appendages one to four, five, and six. What is less well known, although noted in the historical literature, is that the coxae of the 4th and 5th prosomal segments (i.e. walking legs 2 and 3 of camel spiders are also separated ventrally by a distinct membranous region, which is absent between the coxae of the other legs. We suggest that this essentially ventral division of the prosoma specifically between coxae 2 and 3 is homologous with the so-called sejugal furrow (the sejugal interval sensu van der Hammen. This division constitutes a fundamental part of the body plan in acariform mites (Arachnida: Acariformes. If homologous, this sejugal furrow could represent a further potential synapomorphy for (Solifugae + Acariformes; a relationship with increasing morphological and molecular support. Alternatively, outgroup comparison with sea spiders (Pycnogonida and certain early Palaeozoic fossils could imply that the sejugal furrow defines an older tagma, derived from a more basal grade of organisation. In this scenario the (still divided prosoma of acariform mites and camel spiders would be plesiomorphic. This interpretation challenges the textbook arachnid character of a peltidium (or ‘carapace’ covering an undivided prosoma.

  4. Taxonomic revision of the spider family Penestomidae (Araneae, Entelegynae)

    Miller, J.A.; Griswold, C.E.; Haddad, C.R.

    2010-01-01

    Conflicting character evidence and a scarcity of male specimens has historically made placement of the spider subfamily Penestominae Simon problematic. The Penestominae was recently removed from the family Eresidae and promoted to family rank based on the results of a molecular phylogenetic study; a

  5. Czech Republic – the type material of spiders (Araneae)

    Růžička, Vlastimil; Kůrka, A.; Buchar, J.; Řezáč, M.

    2005-01-01

    Roč. 174, 1-4 (2005), s. 13-64 ISSN 0139-9543 R&D Projects: GA AV ČR(CZ) IAA6007401 Institutional research plan: CEZ:AV0Z50070508 Keywords : spider s * type material * Czech Republic Subject RIV: EG - Zoology

  6. On the Colours of Spider Orb-Webs

    Suhr, Wilfried; Schlichting, H. Joachim

    2011-01-01

    A sticky capture thread from the spiral element of spider orb-webs is formed of almost regularly spaced droplets that surround a supporting axial fibre. From the perspective of physical optics it represents a periodic linear array of scattering elements that acts as a diffraction grating. This is a novel aspect, which is of vital importance for…

  7. Central European habitats inhabited by spiders with disjunctive distributions

    Růžička, Vlastimil

    2011-01-01

    Roč. 59, č. 2 (2011), s. 367-380 ISSN 1505-2249 Institutional research plan: CEZ:AV0Z50070508 Keywords : spider s * glacial relicts * boreomontane species Subject RIV: EH - Ecology, Behaviour Impact factor: 0.506, year: 2011

  8. Ballooning behavior in the golden orbweb spider Nephilapilipes (Araneae: Nephilidae

    Vanessa M.J. Lee

    2015-01-01

    Full Text Available Ballooning, a mode of aerial dispersal in spiders, is an innate behavior that requires appropriate physiological and meteorological conditions. Although only rarely reported in the golden orbweb spiders, family Nephilidae, the large geographic distributions of most nephilids—in particular of Nephila species—would imply that these spiders likely routinely disperse by ballooning in spite of giant female sizes. Here we study ballooning behavior in the golden orbweb spider Nephila pilipes (Fabricius, 1793. Specifically, we test for the propensity of spiderlings to deploy ballooning as a dispersal mechanism. We subjected a total of 59 first-instar spiderlings to a wind experiment at two wind speeds (2.17 ± 0.02 m s-1 and 3.17 ± 0.02 m s-1 under laboratory conditions. Under an average wind speed of 3.17 m s-1, none of the spiderlings exhibited pre-ballooning or ballooning behavior. However, at an average wind speed of 2.17 m s-1, 53 (89.8% spiderlings showed pre-ballooning behavior, and 17 (32.1% of the pre-ballooners ultimately ballooned. Our results concur with prior reports on spiderlings of other families that pre-ballooning behavior is a requirement for ballooning to occur. Furthermore, although we cannot rule out other dispersal mechanisms such as synanthropic spread, our findings suggest that the widespread N. pilipes uses ballooning to colonize remote oceanic islands.

  9. Mating duration and sperm precedence in the spider Linyphia triangularis

    Weldingh, Ditte L.; Toft, Søren; Larsen, Ole Næsbye

    2011-01-01

    , especially the males, are able to influence the outcome of mating for their own benefit. We studied the linyphiid spider Linyphia triangularis in which mating follows a strict sequence during which the male inducts two droplets of sperm and transfers them to the female. We performed sperm competition...

  10. Spider diversity in coffee agroecosystems: the influence of agricultural intensification and aggressive ants.

    Marín, Linda; Perfecto, Ivette

    2013-04-01

    Spiders are a very diverse group of invertebrate predators found in agroecosystems and natural systems. However, spider distribution, abundance, and eventually their ecological function in ecosystems can be influenced by abiotic and biotic factors such as agricultural intensification and dominant ants. Here we explore the influence of both agricultural intensification and the dominant arboreal ant Azteca instabilis on the spider community in coffee agroecosystems in southern Mexico. To measure the influence of the arboreal ant Azteca instabilis (F. Smith) on the spider community inhabiting the coffee layer of coffee agroecosystems, spiders were collected from coffee plants that were and were not patrolled by the ant in sites differing in agricultural intensification. For 2008, generalized linear mixed models showed that spider diversity was affected positively by agricultural intensification but not by the ant. However, results suggested that some spider species were associated with A. instabilis. Therefore, in 2009 we concentrated our research on the effect of A. instabilis on spider diversity and composition. For 2009, generalized linear mixed models show that spider richness and abundance per plant were significantly higher in the presence of A. instabilis. In addition, analyses of visual counts of insects and sticky traps data show that more resources were present in plants patrolled by the ant. The positive effect of A. instabilis on spiders seems to be caused by at least two mechanisms: high abundance of insects and protection against predators.

  11. Characteristics of the first recorded spider (Arthropoda: Arachnida fauna from Sheringal, Khyber Pakhtunkhwa, Pakistan

    Farzana Khan Perveen

    2015-12-01

    Full Text Available The spiders (order: Aranae are an important environmental indicator and play a significant role as predators in biological control of the most of the key insect pests. The present study was conducted to establish the characteristics of the first recorded spider fauna from Sheringal, Dir Upper (DU, Khyber Pakhtunkhwa (KP, Pakistan during June 2013-July 2014. Their 10 species belong to 7 families, and 10 genera (nt=123: total; ni=77: identified; nui=46: unidentified were recorded in the 6 quadrates, i.e., Daramdala, Doki, Guryaal, Samang, Shahoor and Sia-Sheringal of Sheringal. The largest family was Lycosidae (wolf spiders with respect to size and numbers of specimens collected (n=20, which contained Arctosa littorali Simon, 1897; Hippasa partita Takidar, 1970; Pardosa distincta Backwall, 1867, while the smallest family was Gnphosidae (ground spiders (n=3 with Gnaphosa eucalyptus Ghafoor and Beg, 2002; while other families Sparassidae (huntsman spiders (n=19 Halconia insignis Thorell, 1836, and Isopeda tuhogniga Barrion and Litsinger, 1995, Opilionidae (harvestmen spiders (n=12 Hadrobunus grandis Sundevall, 1833; Pholcidae (cellar spider (n=10 have Crossopriza lyoni Blackwall, 1867; Hersiliidae (two-tailed spiders (n=6 is having Harsilia savignyi Lucas, 1836; (n=5 with Araneus diadematus Clerck, 1757 were recorded. It was concluded that 50% of the spiders collected from the study area were venomous. A detail study is required for further exploration of spider fauna of Sheringal, KP, Pakistan with special reference to their taxonomical, physiological and ecological characteristics.

  12. Power law-based local search in spider monkey optimisation for lower order system modelling

    Sharma, Ajay; Sharma, Harish; Bhargava, Annapurna; Sharma, Nirmala

    2017-01-01

    The nature-inspired algorithms (NIAs) have shown efficiency to solve many complex real-world optimisation problems. The efficiency of NIAs is measured by their ability to find adequate results within a reasonable amount of time, rather than an ability to guarantee the optimal solution. This paper presents a solution for lower order system modelling using spider monkey optimisation (SMO) algorithm to obtain a better approximation for lower order systems and reflects almost original higher order system's characteristics. Further, a local search strategy, namely, power law-based local search is incorporated with SMO. The proposed strategy is named as power law-based local search in SMO (PLSMO). The efficiency, accuracy and reliability of the proposed algorithm is tested over 20 well-known benchmark functions. Then, the PLSMO algorithm is applied to solve the lower order system modelling problem.

  13. Synthetic Spider Silk Production on a Laboratory Scale

    Hsia, Yang; Gnesa, Eric; Pacheco, Ryan; Kohler, Kristin; Jeffery, Felicia; Vierra, Craig

    2012-01-01

    As society progresses and resources become scarcer, it is becoming increasingly important to cultivate new technologies that engineer next generation biomaterials with high performance properties. The development of these new structural materials must be rapid, cost-efficient and involve processing methodologies and products that are environmentally friendly and sustainable. Spiders spin a multitude of different fiber types with diverse mechanical properties, offering a rich source of next generation engineering materials for biomimicry that rival the best manmade and natural materials. Since the collection of large quantities of natural spider silk is impractical, synthetic silk production has the ability to provide scientists with access to an unlimited supply of threads. Therefore, if the spinning process can be streamlined and perfected, artificial spider fibers have the potential use for a broad range of applications ranging from body armor, surgical sutures, ropes and cables, tires, strings for musical instruments, and composites for aviation and aerospace technology. In order to advance the synthetic silk production process and to yield fibers that display low variance in their material properties from spin to spin, we developed a wet-spinning protocol that integrates expression of recombinant spider silk proteins in bacteria, purification and concentration of the proteins, followed by fiber extrusion and a mechanical post-spin treatment. This is the first visual representation that reveals a step-by-step process to spin and analyze artificial silk fibers on a laboratory scale. It also provides details to minimize the introduction of variability among fibers spun from the same spinning dope. Collectively, these methods will propel the process of artificial silk production, leading to higher quality fibers that surpass natural spider silks. PMID:22847722

  14. Brown Spider (Loxosceles genus Venom Toxins: Tools for Biological Purposes

    Andrea Senff-Ribeiro

    2011-03-01

    Full Text Available Venomous animals use their venoms as tools for defense or predation. These venoms are complex mixtures, mainly enriched of proteic toxins or peptides with several, and different, biological activities. In general, spider venom is rich in biologically active molecules that are useful in experimental protocols for pharmacology, biochemistry, cell biology and immunology, as well as putative tools for biotechnology and industries. Spider venoms have recently garnered much attention from several research groups worldwide. Brown spider (Loxosceles genus venom is enriched in low molecular mass proteins (5–40 kDa. Although their venom is produced in minute volumes (a few microliters, and contain only tens of micrograms of protein, the use of techniques based on molecular biology and proteomic analysis has afforded rational projects in the area and permitted the discovery and identification of a great number of novel toxins. The brown spider phospholipase-D family is undoubtedly the most investigated and characterized, although other important toxins, such as low molecular mass insecticidal peptides, metalloproteases and hyaluronidases have also been identified and featured in literature. The molecular pathways of the action of these toxins have been reported and brought new insights in the field of biotechnology. Herein, we shall see how recent reports describing discoveries in the area of brown spider venom have expanded biotechnological uses of molecules identified in these venoms, with special emphasis on the construction of a cDNA library for venom glands, transcriptome analysis, proteomic projects, recombinant expression of different proteic toxins, and finally structural descriptions based on crystallography of toxins.

  15. Global patterns of guild composition and functional diversity of spiders.

    Pedro Cardoso

    Full Text Available The objectives of this work are: (1 to define spider guilds for all extant families worldwide; (2 test if guilds defined at family level are good surrogates of species guilds; (3 compare the taxonomic and guild composition of spider assemblages from different parts of the world; (4 compare the taxonomic and functional diversity of spider assemblages and; (5 relate functional diversity with habitat structure. Data on foraging strategy, prey range, vertical stratification and circadian activity was collected for 108 families. Spider guilds were defined by hierarchical clustering. We searched for inconsistencies between family guild placement and the known guild of each species. Richness and abundance per guild before and after correcting guild placement were compared, as were the proportions of each guild and family between all possible pairs of sites. Functional diversity per site was calculated based on hierarchical clustering. Eight guilds were discriminated: (1 sensing, (2 sheet, (3 space, and (4 orb web weavers; (5 specialists; (6 ambush, (7 ground, and (8 other hunters. Sixteen percent of the species richness corresponding to 11% of all captured individuals was incorrectly attributed to a guild by family surrogacy; however, the correlation of uncorrected vs. corrected guilds was invariably high. The correlation of guild richness or abundances was generally higher than the correlation of family richness or abundances. Functional diversity was not always higher in the tropics than in temperate regions. Families may potentially serve as ecological surrogates for species. Different families may present similar roles in the ecosystems, with replacement of some taxa by other within the same guild. Spiders in tropical regions seem to have higher redundancy of functional roles and/or finer resource partitioning than in temperate regions. Although species and family diversity were higher in the tropics, functional diversity seems to be also

  16. SPIDERS (ARANEI OF THE REPUBLIC OF SOUTH OSSETIA

    Alexander V. Ponomarev

    2015-01-01

    Full Text Available Aim. Until recently, spider fauna of the Republic of South Ossetia has been the least studied among the regional araneofaunas of the Caucasus. According to the literature data, as little as 30 spider species have been known from the republic’s territory (Mkheidze, 1997, Mikhailov, 1990; Ponomarev, Dvadnenko, 2013; Trilicauscas, Komarov, 2014. Therefore, the aim of the present article is to summarize available data on the spider fauna of South Ossetia.Location. Republic of South Ossetia.Methods. The material was collected in various districts of South Ossetia in 2011-2014 by Yu.E. Komarov. Mainly, the collecting was performed in the city of Tskhinvali and its environs, and in the South Ossetian State Reserve. Spiders were sampled with pitfall traps and sweep netting. The time of traps’ exposure is April–December.Results and main conclusions. To date, the spider fauna of the Republic of South Ossetia includes 230 species from 29 families. 222 species were registered by the authors, eight species (Clubiona pseudosimilis, Gnaphosa lugubris, Linyphia hortensis, Neriene peltata, Geolycosa vultuosa, Pardosa azerifalcata, Ero aphana, and Philodromus rufus are known from the literature only. Seven species are new to the Caucasus (Clubiona pseudosimilis, Gnaphosa lugubris, Linyphia hortensis, Neriene peltata, Geolycosa vultuosa, Pardosa azerifalcata, Ero aphana, and Philodromus rufus. Of these, two species were known earlier only from Turkey (Pardosa consimilis, Ozyptila spirembolus, and one species (Tegenaria pseudolyncea only from Azerbaijan. Against the background of the widespread species predominance, the Caucasian element is small and presented by twelve species (Tegenaria pseudolyncea, Dysdera tkibuliensis, Haplodrassus caucasius, Zelotes khostensis, Mansuphantes ovalis, Sintula oseticus, Tenuiphantes teberdaensis, Pardosa azerifalcata, P. caucasica, Piratula hurkai, Trochosa cachetiensis, and Xysticus ukrainicus.

  17. Spider silk MASP1 and MASP2 proteins as carbon fiber precursors

    Lewis, Randolph V [Utah State Univ., Logan, UT (United States)

    2017-06-14

    The objective of this project is to develop an unconventional non-petroleum based carbon fiber precursor which has the potential to be produced in high yield and quantities. Methods will be developed to produce pilot-scale quantities of fibers from spider silk proteins with mechanical properties at least 75% that of the natural dragline silk fibers in tensile strength and elongations of less than 5%. The precursor fibers will be converted to carbon fibers, with a goal of >250Ksi strength and 1-2% elongation. Cost analysis will be performed and the process optimized. Task 1: Subtask 1. Protein production: We exceeded the go/ no go milestone of 1.0g/L of one of the spider silk protein (MSp2) purified last FY and have now increased from 5L to 500L fermentations. We have made a series of changes to the purification protocol from the initial report last FY. These led to a reduction in the time needed for the purification and reduced the purification costs by nearly 90%. Subtask 2. Fiber spinning: The major focus has been to produce more material to send 24 fiber thread to ONRL. We are still developing the methodology to successfully spin 24 fiber yarns. This involves both the spinning dope solutions as well as the methods to keep the fibers from fusing during the post spin stretch. The second area of focus has been to standardize the spin dopes for making the fibers. We now know that the conductivity (indicative of salt remaining with the protein after purification) is an important factor in successful spinning as is the pH. We now know that we need to be below 600 uS conductivity and that the most effective pH is protein dependent. Subtask 3. Silkworm silk: We have found the transgenic silkworms made using gene replacement at the fibroin light chain instead of heavy chain as we did previously have a higher tensile strength. See figures below showing the curve for the top end of the cocoon fibers. This tensile strength is the same as the average for spider dragline silk

  18. Complementary microanalysis of Zn, Mn and Fe in the chelicera of spiders and scorpions using scanning MeV-ion and electron microprobes

    Schofield, R.; Lefevre, H.; Shaffer, M.

    1989-01-01

    Energy-loss scanning transmission ion microscopy (ELSTIM or just STIM), PIXE and electron microprobe techniques are used to investigate certain minor element accumulations in a few spiders and scorpions. STIM and PIXE are used to survey the unsectioned specimens, while electron microprobe techniques are used for higher resolution investigations of several sections of the specimens. Concentration values measured using STIM and PIXE are found to be in satisfactory agreement with those measured using electron probe microanalysis. A garden spider Araneous diadematus is found to contain high concentrations of zinc in a thin layer near the surface of its fangs (reaching 23% of dry weight), and manganese in its marginal teeth (about 5% of dry weight). A wolf spider Alopecosa kochi is found to have similar concentrations of zinc in a layer near the surface of it's fang, and concentrations of manganese reaching 1.5% in a layer beneath the zinc containing layer. A scorpion Centruroides sp. is found to contain high concentrations of iron (reaching 8%) and zinc (reaching 24%) in the tips of teeth on the cheliceral fingers, and manganese (about 5%) in the stinger. The hypothesis that these elements simply harden the cuticle does not appear to explain their segregation patterns. (orig.)

  19. Competitive interactions between a native spider (Frontinella communis, Araneae: Linyphiidae) and an invasive spider (Linyphia triangularis, Araneae: Linyphiidae)

    Bednarski, Julie V.; Ginsberg, Howard S.; Jakob, Elizabeth M.

    2010-01-01

    There are numerous reports of spiders that have become established outside of their native ranges, but few studies examine their impact on native spiders. We examined the effect of the European hammock spider Linyphia triangularis (Araneae, Linyphiidae) on the native bowl-and-doily spider Frontinella communis (Araneae, Linyphiidae) in Acadia National Park, Maine, USA. First, we added L. triangularis to established plots of F. communis. Significantly more F. communis abandoned their webs when L. triangularis were added compared to control plots. Second, we tested whether F. communis were deterred from building webs in areas where L. triangularis was established. Significantly fewer F. communis built webs on plots with L. triangularis than on control plots. In both experiments, L. triangularis sometimes took over webs of F. communis or incorporated F. communis webs into their own webs, but F. communisnever took over or incorporated L. triangularis webs. Competition between L. triangularis and F. communis for both webs and web sites may contribute to the decline of F. communis.

  20. Invited review current progress and limitations of spider silk for biomedical applications.

    Widhe, Mona; Johansson, Jan; Hedhammar, My; Rising, Anna

    2012-06-01

    Spider silk is a fascinating material combining remarkable mechanical properties with low density and biodegradability. Because of these properties and historical descriptions of medical applications, spider silk has been proposed to be the ideal biomaterial. However, overcoming the obstacles to produce spider silk in sufficient quantities and in a manner that meets regulatory demands has proven to be a difficult task. Also, there are relatively few studies of spider silk in biomedical applications available, and the methods and materials used vary a lot. Herein we summarize cell culture- and in vivo implantation studies of natural and synthetic spider silk, and also review the current status and future challenges in the quest for a large scale production of spider silk for medical applications. Copyright © 2011 Wiley Periodicals, Inc.

  1. Research on Artificial Spider Web Model for Farmland Wireless Sensor Network

    Jun Wang

    2018-01-01

    Full Text Available Through systematic analysis of the structural characteristics and invulnerability of spider web, this paper explores the possibility of combining the advantages of spider web such as network robustness and invulnerability with farmland wireless sensor network. A universally applicable definition and mathematical model of artificial spider web structure are established. The comparison between artificial spider web and traditional networks is discussed in detail. The simulation result shows that the networking structure of artificial spider web is better than that of traditional networks in terms of improving the overall reliability and invulnerability of communication system. A comprehensive study on the advantage characteristics of spider web has important theoretical and practical significance for promoting the invulnerability research of farmland wireless sensor network.

  2. How informative are case studies of spider bites in the medical literature?

    Stuber, Marielle; Nentwig, Wolfgang

    2016-05-01

    We analyzed the reliability and information content of 134 medical case studies on spider bites, published in 91 journal articles. Overall, we found that only 22% of these studies fulfilled the criteria for a verified spider bite. This means that the majority of such case studies cannot be attributed to a given spider species and usually not even to a spider. Their scientific value is negligible, moreover, such publications are even dangerous because they suggest incorrect conclusions. Secondly, we found that such case studies usually do not follow an obvious structure and many details on the development of symptoms, therapy and healing process are widely lacking. So even for verified spider bites, the comparability of case studies is limited. We discuss the obvious failure of a reviewing process for case studies and give recommendations how to increase the currently low information content of medical case studies on spider bites. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Plastic material investment in load-bearing silk attachments in spiders.

    Wolff, Jonas O; Jones, Braxton; Herberstein, Marie E

    2018-05-17

    The nature and size of attachments is a fundamental element of animal constructions. Presumably, these adhesive structures are plastically deployed to balance material investment and attachment strength. Here we studied plasticity in dragline anchorages of the golden orb web spider, Nephila plumipes. Specifically, we predict that spiders adjust the size and structure of dragline anchorages with load, i.e. spider mass. Mass was manipulated by attaching lead pieces to the spider's abdomen resulting in a 50 percent increase in mass. Loaded spiders spun larger but structurally similar thread anchorages than unloaded spiders. Thus, the spinning program that determines the overall anchor structure is highly stereotypic, and flexibility is introduced through varying the anchor size by increasing material investment. Our study showcases substrate attachments as suitable models to investigate the interplay between innate and changeable elements in the economy of building behaviours. Copyright © 2018 Elsevier GmbH. All rights reserved.

  4. Rapid visuomotor processing of phobic images in spider- and snake-fearful participants.

    Haberkamp, Anke; Schmidt, Filipp; Schmidt, Thomas

    2013-10-01

    This study investigates enhanced visuomotor processing of phobic compared to fear-relevant and neutral stimuli. We used a response priming design to measure rapid, automatic motor activation by natural images (spiders, snakes, mushrooms, and flowers) in spider-fearful, snake-fearful, and control participants. We found strong priming effects in all tasks and conditions; however, results showed marked differences between groups. Most importantly, in the group of spider-fearful individuals, spider pictures had a strong and specific influence on even the fastest motor responses: Phobic primes entailed the largest priming effects, and phobic targets accelerated responses, both effects indicating speeded response activation by phobic images. In snake-fearful participants, this processing enhancement for phobic material was less pronounced and extended to both snake and spider images. We conclude that spider phobia leads to enhanced processing capacity for phobic images. We argue that this is enabled by long-term perceptual learning processes. © 2013.

  5. Evolutionary morphology of the hemolymph vascular system of basal araneomorph spiders (Araneae: Araneomorphae).

    Huckstorf, Katarina; Michalik, Peter; Ramírez, Martín; Wirkner, Christian S

    2015-11-01

    The superfamily Austrochiloidea (Austrochilidae and Gradungulidae) take a pivotal position in araneomorph spider phylogeny. In this discussion crevice weaver spiders (Filistatidae) are of equal interest. Especially data from these phylogenetically uncertain yet basal off branching groups can enlighten our understanding on the evolution of organ systems. In the course of a survey on the evolutionary morphology of the circulatory system in spiders we therefore investigated the hemolymph vascular system in two austrochiloid and one filistatid species. Additionally some data on a hypochilid and a gradungulid species are included. Using up-to-date morphological methods, the vascular systems in these spiders are visualized three dimensionally. Ground pattern features of the circulatory systems in austrochiloid spiders are presented and the data discussed along recent lines of phylogenetic hypotheses. Special topics highlighted are the intraspecific variability of the origins of some prosomal arteries and the evolutionary correlation of respiratory and circulatory systems in spiders. Copyright © 2015 Elsevier Ltd. All rights reserved.

  6. A Concept for Optimizing Behavioural Effectiveness & Efficiency

    Barca, Jan Carlo; Rumantir, Grace; Li, Raymond

    Both humans and machines exhibit strengths and weaknesses that can be enhanced by merging the two entities. This research aims to provide a broader understanding of how closer interactions between these two entities can facilitate more optimal goal-directed performance through the use of artificial extensions of the human body. Such extensions may assist us in adapting to and manipulating our environments in a more effective way than any system known today. To demonstrate this concept, we have developed a simulation where a semi interactive virtual spider can be navigated through an environment consisting of several obstacles and a virtual predator capable of killing the spider. The virtual spider can be navigated through the use of three different control systems that can be used to assist in optimising overall goal directed performance. The first two control systems use, an onscreen button interface and a touch sensor, respectively to facilitate human navigation of the spider. The third control system is an autonomous navigation system through the use of machine intelligence embedded in the spider. This system enables the spider to navigate and react to changes in its local environment. The results of this study indicate that machines should be allowed to override human control in order to maximise the benefits of collaboration between man and machine. This research further indicates that the development of strong machine intelligence, sensor systems that engage all human senses, extra sensory input systems, physical remote manipulators, multiple intelligent extensions of the human body, as well as a tighter symbiosis between man and machine, can support an upgrade of the human form.

  7. Induction of direct and indirect plant responses by jasmonic acid, low spider mite densities, or a combination of jasmonic acid treatment and spider mite infestation.

    Gols, Rieta; Roosjen, Mara; Dijkman, Herman; Dicke, Marcel

    2003-12-01

    Jasmonic acid (JA) and the octadecanoid pathway are involved in both induced direct and induced indirect plant responses. In this study, the herbivorous mite, Tetranychus urticae, and its predator, Phytoseiulus persimilis, were given a choice between Lima bean plants induced by JA or spider mites and uninduced control plants. Infestation densities resulting in the induction of predator attractants were much lower than thus far assumed, i.e., predatory mites were significantly attracted to plants that were infested for 2 days with only one or four spider mites per plant. Phytoseiulus persimilis showed a density-dependent response to volatiles from plants that were infested with different numbers of spider mites. Similarly, treating plants with increasing concentrations of JA also led to increased attraction of P. persimilis. Moreover, the duration of spider mite infestation was positively correlated with the proportion of predators that were attracted to mite-infested plants. A pretreatment of the plants with JA followed by a spider mite infestation enhanced the attraction of P. persimilis to plant volatiles compared to attraction to volatiles from plants that were only infested with spider mites and did not receive a pretreatment with JA. The herbivore, T. urticae preferred leaf tissue that previously had been infested with conspecifics to uninfested leaf tissue. In the case of choice tests with JA-induced and control leaf tissue, spider mites slightly preferred control leaf tissue. When spider mites were given a choice between leaf discs induced by JA and leaf discs damaged by spider mite feeding, they preferred the latter. The presence of herbivore induced chemicals and/or spider mite products enhanced settlement of the mites, whereas treatment with JA seemed to impede settlement.

  8. Ontogenesis, gender, and molting influence the venom yield in the spider Coremiocnemis tropix (Araneae, Theraphosidae)

    Herzig, Volker

    2010-01-01

    The demand for spider venom increases along with the growing popularity of venoms-based research. A deeper understanding of factors that influence the venom yield in spiders would therefore be of interest to both commercial venom suppliers and research facilities. The present study addresses the influence of several factors on the venom yield by systematically analyzing the data obtained from 1773 electrical milkings of the Australian theraphosid spider Coremiocnemis tropix. Gender and ontoge...

  9. On the predation of fly, Chrysomya rufifacies (Macquart) by a spider, Oxyopes sp. Latreille (Oxyopidae).

    Heo, C C; Mohamad, A M; John, J; Baharudin, O

    2008-04-01

    During a forensic entomological study conducted in a palm oil plantation in Tg.Sepat, Selangor in September 2007, a spider (Arachnida), Oxyopes sp. (Oxyopidae) was found to predate on a calliphorid fly (Chrysomya rufifacies). The female spider laid a silk thread, or "drag line", behind it as it moved. This spider bites its prey by using a pairs of chelicerae, and injecting venom into the fly. The fly was moving its wing trying to escape, however, it succumbed to the deadly bite.

  10. Exploring of the first recorded spider (Arachenida: Aranae) species of Sheringal, Khyber Pakhtunkhwa, Pakistan

    Farzana Perveen; Numan Khan

    2015-01-01

    The spiders (Arthropoada: Arachenida) are one of the groups of grasping animals. Their carapaces are found on the dorsal side of the cephalothorax, which is an important characteristic of spiders. The present study was conducted to explore the first recorded spider species (nti=75) of Sheringal, Dir Upper (DU), Khyber Pakhtunkhwa (KP), Dir Upper, Khyber Pakhtunkhwa, Pakistan. The 10 genera with 10 species under 7 families were recorded from June 2013-July 2014. According to length of legs, th...

  11. Cuticular bacteria appear detrimental to social spiders in mixed but not monoculture exposure

    Keiser, Carl N.; Shearer, Taylor A.; DeMarco, Alexander E.; Brittingham, Hayley A.; Knutson, Karen A.; Kuo, Candice; Zhao, Katherine; Pruitt, Jonathan N.

    2016-01-01

    Abstract Much of an animal’s health status, life history, and behavior are dictated by interactions with its endogenous and exogenous bacterial communities. Unfortunately, interactions between hosts and members of their resident bacterial community are often ignored in animal behavior and behavioral ecology. Here, we aim to identify the nature of host–microbe interactions in a nonmodel organism, the African social spider Stegodyphus dumicola. We collected and identified bacteria from the cuticles of spiders in situ and then exposed spiders to bacterial monocultures cultures via topical application or injection. We also topically inoculated spiders with a concomitant “cocktail” of bacteria and measured the behavior of spiders daily for 24 days after inoculation. Lastly, we collected and identified bacteria from the cuticles of prey items in the capture webs of spiders, and then fed spiders domestic crickets which had been injected with these bacteria. We also injected 1 species of prey-borne bacteria into the hemolymph of spiders. Only Bacillus thuringiensis caused increased mortality when injected into the hemolymph of spiders, whereas no bacterial monocultures caused increased mortality when applied topically, relative to control solutions. However, a bacterial cocktail of cuticular bacteria caused weight loss and mortality when applied topically, yet did not detectibly alter spider behavior. Consuming prey injected with prey-borne bacteria was associated with an elongated lifespan in spiders. Thus, indirect evidence from multiple experiments suggests that the effects of these bacteria on spider survivorship appear contingent on their mode of colonization and whether they are applied in monoculture or within a mixed cocktail. We urge that follow-up studies should test these host–microbe interactions across different social contexts to determine the role that microbes play in colony performance. PMID:29491926

  12. Exploring of the first recorded spider (Arachenida: Aranae species of Sheringal, Khyber Pakhtunkhwa, Pakistan

    Farzana Perveen

    2015-09-01

    Full Text Available The spiders (Arthropoada: Arachenida are one of the groups of grasping animals. Their carapaces are found on the dorsal side of the cephalothorax, which is an important characteristic of spiders. The present study was conducted to explore the first recorded spider species (nti=75 of Sheringal, Dir Upper (DU, Khyber Pakhtunkhwa (KP, Dir Upper, Khyber Pakhtunkhwa, Pakistan. The 10 genera with 10 species under 7 families were recorded from June 2013-July 2014. According to length of legs, the largest spider was the huntsman spider, Halconia insignis Thorell having length of the first leg was 1.9±0.20, however, the same of the last leg was 1.44±0.25 (n=9. In the same contest, the smallest spider was the ground spider, Gnaphosa eucalyptus Ghafoor and Beg having length of the first leg was 0.4±0.08, while the same of the last leg was 0.4±0.08 (n=3. According to length of cephalothorax and abdomen, the largest spider was the wolf spider, Hippasa partita Takidar having length of the cephalothorax was 1.1±0.01, however, the same of the abdomen was 0.7±0.1 (n=6. In the same contest, the smallest spider was the harvestmen, Hadrobunus grandis Sundevall having length of the cephalothorax was 0.1±0.04, while the same of the abdomen was 0.3±0.04 (n=12. During present research, 10 spider species of Sheringal with different sizes were explored. The present research will be useful to educate and create awareness about spiders in the people of Sheringal.

  13. Ecosystem services in the face of invasion: the persistence of native and nonnative spiders in an agricultural landscape.

    Hogg, Brian N; Daane, Kent M

    2011-03-01

    The presence of intact natural ecosystems in agricultural landscapes can mitigate losses in the diversity of natural enemies and enhance ecosystem services. However, native natural enemies may fail to persist in agroecosystems if invaders dominate species interactions. In this study, native and nonnative spiders were sampled along transects that extended from oak woodland and riparian zones into surrounding California vineyards, to assess the role of natural habitat as a source for spider biodiversity in the vineyard landscape, and to compare the dominance of exotic Cheiracanthium spiders between habitats. Many spider species were more abundant in natural habitat than in vineyards, and numbers of spiders and spider species within vineyards were higher at the vineyard edge adjacent to oak woodland. These results suggest that natural habitat is a key source for spiders in vineyards. The positive effect of oak woodland on the vineyard spider community extended only to the vineyard edge, however. Proportions of Cheiracanthium spiders increased dramatically in the vineyard, while numbers of native wandering spiders (the native ecological homologues of Cheiracanthium spiders) decreased. Dispersal limitation and strong habitat preferences may have prevented native wandering spiders from establishing far from the vineyard edge. Exotic Cheiracanthium spiders, in contrast, may possess specific adaptations to vineyards or to a wide range of habitats. Results suggest that the ecosystem services provided by intact natural habitat may be limited in agricultural landscapes that are dominated by invasive species.

  14. Gas fluxing of aluminum: a bubble probe for optimization of bubbles/bubble distribution and minimization of splashing/droplet formation

    James W. Evans; Auitumn Fjeld

    2006-01-01

    totaling 1.549 million lbs. for only thirteen of the twenty three primary smelters then in operation in the US. The research work described in the body of this report (the doctoral dissertation of Dr. Autumn M. Fjeld) had as its objective the improvement of gas fluxing technology to reduce emissions while still maintaining fluxing unit metal throughput. A second objective was a better understanding of the splashing and droplet emission that occurs during fluxing at high gas throughput rates. In the extreme such droplets can form undesired accretions on the walls and gas exit lines of the fluxing unit. Consequently, the productivity of a fluxing unit is sometimes limited by the need to avoid such spraying of droplets produced as gas bubbles break at the metal surface. The approach used was a combination of experimental work in laboratories at UC Berkeley and at the Alcoa Technical Center. The experimental work was mostly on a bubble probe that could be used to determine the extent of dispersion of gas bubbles in the fluxing unit (a parameter affecting the utilization of the injected chlorine). Additionally a high speed digital movie camera was used to study droplet formation due to gas bubbles bursting at the surface of a low melting point alloy. The experimental work was supported by mathematical modeling. In particular, two FLUENT? base mathematical models were developed to compute the metal flow and distribution of the gas within a fluxing unit. Results from these models were then used in a third model to compute emissions and the progress of impurity removal as a function of parameters such as rotor speed. The project was successful in demonstrating that the bubble probe could detect bubbles in a gas fluxing unit at the Alcoa technical Center outside Pittsburgh, PA. This unit is a commercial sized one and the probe, with its associated electronics, was subjected to the hostile molten aluminum, electrical noise etc. Despite this the probes were, on several occasions

  15. Information processing biases in spider phobia: application of the Stroop and "White Noise" Paradigm.

    Olatunji, Bunmi O; Sawchuk, Craig N; Lee, Thomas C; Lohr, Jeffrey M; Tolin, David F

    2008-06-01

    The present study examines attentional and implicit memory biases in spider phobic and nonphobic participants. The results showed that spider phobics demonstrated increased interference for neutral, negative, and spider-relevant words on a computerized Stroop task. However, no group differences emerged when adjusting for differences in color-naming speed. Prior exposure to a dead spider did result in higher overall Stroop interference in spider phobics and this appeared to be mostly pronounced for spider-relevant words. Implicit memory bias for threat was examined with a noise judgment task. Participants first heard neutral and spider-relevant sentences and implicit memory for these sentences was evaluated by having participants rate the volume of noise accompanying the presentation of old sentences intermixed with new sentences. An implicit memory bias is indicated if participants rate noise accompanying old sentences as less loud than noise accompanying new sentences. No evidence was found for an implicit memory bias in spider phobics. These findings are discussed in relation to the role of information processing biases in spider phobia.

  16. Biased interpretation and memory in children with varying levels of spider fear.

    Klein, Anke M; Titulaer, Geraldine; Simons, Carlijn; Allart, Esther; de Gier, Erwin; Bögels, Susan M; Becker, Eni S; Rinck, Mike

    2014-01-01

    This study investigated multiple cognitive biases in children simultaneously, to investigate whether spider-fearful children display an interpretation bias, a recall bias, and source monitoring errors, and whether these biases are specific for spider-related materials. Furthermore, the independent ability of these biases to predict spider fear was investigated. A total of 121 children filled out the Spider Anxiety and Disgust Screening for Children (SADS-C), and they performed an interpretation task, a memory task, and a Behavioural Assessment Test (BAT). As expected, a specific interpretation bias was found: Spider-fearful children showed more negative interpretations of ambiguous spider-related scenarios, but not of other scenarios. We also found specific source monitoring errors: Spider-fearful children made more fear-related source monitoring errors for the spider-related scenarios, but not for the other scenarios. Only limited support was found for a recall bias. Finally, interpretation bias, recall bias, and source monitoring errors predicted unique variance components of spider fear.

  17. Body burdens of metals in spiders from the Lidice coal dump near Ostrava (Czech Republic)

    Wilczek, G.; Babczynska, A.; Majkus, Z. [Silesian University, Katowice (Poland)

    2005-09-01

    Spiders' feeding behaviour and external digestion expose them to man-made pollutants, especially those easily transferred along the food chain. The problem for this study was whether the levels of heavy metals in selected species of spiders from the Lidice coal dump reflect adaptation to environmental pollutants. We used flameless and flame AAS to measure the whole-body concentrations of Cd, Pb, Cu, Zn, Fe, Ni and Mg in male and female spiders differing in their hunting strategies, type of web construction, prey, and taxonomic position (Araneidae, Agelenidae, Linyphiidae, Theridiidae, Tetragnathidae, Lycosidae, Salticidae, Pisauridae, Clubionidae, Philodromidae). The levels of metals found in the spiders were species-dependent, indicating differences related to the hunting strategy and type of prey. Accumulation of Pb, Cu and Zn was always higher in ground spiders than in web-constructing species. Sheet-web spiders Linyphia triangularis and wandering spiders Clubiona lutescens had the lowest Cd, Mg and Cu content of all the studied species. Web-building spiders of the Tetragnathidae family showed the highest Cd, Cu and Pb content, even in species with feeding behaviour similar to spiders of other families. There were no interspecific differences in accumulation only for Fe and Mg. The concentrations of Cd, Ni and Pb were lower in females than in males, irrespective of their taxonomic position and the intensity of their hunting activity. This may suggest that females have better metal-excretion ability than males.

  18. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    Edwards, G.T.; Schluderberg, D.C.

    1981-01-01

    A technique is provided for engaging and disengaging burnable poison rods from a spider in a nuclear reactor fuel assembly. A cap on the end of each of the burnable poison rods is provided with a shank or stem that is received in a respective bore formed in the spider. A frangible flange secures the shank and rod to the spider. Pressing the shank in the direction of the bore axis by means, e.g., of a plate ruptures the frangible flange to release the rod from the spider. (author)

  19. Spiders do not evoke greater early posterior negativity in the event-related potential as snakes.

    He, Hongshen; Kubo, Kenta; Kawai, Nobuyuki

    2014-09-10

    It has been long believed that both snakes and spiders are archetypal fear stimuli for humans. Furthermore, snakes have been assumed as stronger threat cues for nonhuman primates. However, it is still unclear whether spiders hold a special status in human perception. The current study explored to what extent spider pictures draw early visual attention [as assessed with early posterior negativity (EPN)] when compared with insects similar to spiders. To measure the EPN, participants watched a random rapid serial presentation of pictures, which consisted of two conditions: spider condition (spider, wasp, bumblebee, beetle) and snake condition (snake, bird). EPN amplitudes revealed no significant difference between spider, wasp, bumblebee, and beetle pictures, whereas EPN amplitudes were significantly larger for snake pictures relative to bird pictures. In addition, EPN amplitudes were significantly larger for snake pictures relative to spider pictures. These results suggest that the early visual attentional capture of animate objects is stronger for snakes, whereas spiders do not appear to hold special early attentional value.

  20. Risk of spider predation alters food web structure and reduces local herbivory in the field.

    Bucher, Roman; Menzel, Florian; Entling, Martin H

    2015-06-01

    Predators can indirectly enhance plant performance via herbivore suppression, with both prey consumption and changes in prey traits (e.g. changes in foraging behaviour) contributing to the reduction in herbivory. We performed a field experiment to determine the extent of such non-consumptive effects which consisted of repeatedly placing spiders (Pisaura mirabilis) on enclosed plants (Urtica dioica) for cue deposition. Control plants were enclosed in the same way but without spiders. After cue deposition, the enclosures were removed to allow arthropods to colonize the plants and feed on them. Arthropods were removed from the plants before the subsequent spider deposition or control enclosure. During six cycles of enclosure, we quantified leaf damage on the plants. After a seventh cycle, the colonizing arthropods were sampled to determine community composition in relation to the presence/absence of spider cues. We found that the presence of chemotactile spider cues reduced leaf damage by 50 %. In addition, spider cues led to changes in the arthropod community: smaller spiders avoided plants with spider cues. In contrast, the aphid-tending ant Myrmica rubra showed higher recruitment of workers on cue-bearing plants, possibly to protect aphids. Our results show that the risk of spider predation can reduce herbivory on wild plants and also demonstrate that non-consumptive effects can be particularly strong within the predator guild.

  1. Spider Transcriptomes Identify Ancient Large-Scale Gene Duplication Event Potentially Important in Silk Gland Evolution.

    Clarke, Thomas H; Garb, Jessica E; Hayashi, Cheryl Y; Arensburger, Peter; Ayoub, Nadia A

    2015-06-08

    The evolution of specialized tissues with novel functions, such as the silk synthesizing glands in spiders, is likely an influential driver of adaptive success. Large-scale gene duplication events and subsequent paralog divergence are thought to be required for generating evolutionary novelty. Such an event has been proposed for spiders, but not tested. We de novo assembled transcriptomes from three cobweb weaving spider species. Based on phylogenetic analyses of gene families with representatives from each of the three species, we found numerous duplication events indicative of a whole genome or segmental duplication. We estimated the age of the gene duplications relative to several speciation events within spiders and arachnids and found that the duplications likely occurred after the divergence of scorpions (order Scorpionida) and spiders (order Araneae), but before the divergence of the spider suborders Mygalomorphae and Araneomorphae, near the evolutionary origin of spider silk glands. Transcripts that are expressed exclusively or primarily within black widow silk glands are more likely to have a paralog descended from the ancient duplication event and have elevated amino acid replacement rates compared with other transcripts. Thus, an ancient large-scale gene duplication event within the spider lineage was likely an important source of molecular novelty during the evolution of silk gland-specific expression. This duplication event may have provided genetic material for subsequent silk gland diversification in the true spiders (Araneomorphae). © The Author(s) 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  2. Spider (Araneae) predations on white-backed planthopper Sogatella furcifera in subtropical rice ecosystems, China.

    Wang, Xue-Qin; Wang, Guang-Hua; Zhu, Zeng-Rong; Tang, Qi-Yi; Hu, Yang; Qiao, Fei; Heong, Kong Luen; Cheng, Jia-An

    2017-06-01

    Spiders are effective biological control agents in rice ecosystems, but the comparative study of predations among main spider species under field conditions has not been fully explored owing to a lack of practical methodology. In this study, more than 6000 spiders of dominant species were collected from subtropical rice ecosystems to compare their predations on Sogatella furcifera (Horváth) (white-backed planthopper, WBPH) using DNA-based gut content analysis. The positive rates for all spider taxa were closely related to prey densities, as well as their behaviors and niches. The relationships of positive rates to prey planthopper densities for Pardosa pseudoannulata (Böes. et Str.), Coleosoma octomaculata (Böes. et Str.), Tetragnatha maxillosa Thorell and Ummeliata insecticeps (Böes. et Str.) under field conditions could be described using saturated response curves. Quantitative comparisons of predations among the four spider species confirmed that P. pseudoannulata and C. octomaculata were more rapacious than U. insecticeps and T. maxillosa under field conditions. A comparison of ratio of spiders to WBPH and positive rates between fields revealed that biological control by spiders could be effectively integrated with variety resistance. Generalist spiders could follow up WBPH population timely, and assemblages of spiders coupled with variety resistance could effectively suppress WBPH population. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  3. A comparison of spider communities in Bt and non-Bt rice fields.

    Lee, Sue Yeon; Kim, Seung Tae; Jung, Jong Kook; Lee, Joon-Ho

    2014-06-01

    To assess the potential adverse effects of a Bt rice line (Japonica rice cultivar, Nakdong) expressing a synthetic cry1Ac1 gene, C7-1-9-1-B, which was highly active against all larval stages of Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Crambidae), we investigated the community structure of spiders in Bt and non-Bt rice fields during the rice-growing season in 2007 and 2008 in Chungcheongnam-do, Korea. Spiders were surveyed with a sweep net and suction device. Suction sampling captured more spiders, measured in terms of species level and abundance, than sweeping. Araneidae and Thomisidae were captured more by sweeping, and certain species were captured only by sweeping. These findings show that both suction and sweep sampling methods should be used because these methods are most likely complementary. In total, 29 species in 23 genera and nine families were identified from the 4,937 spiders collected, and both Bt and non-Bt rice fields showed a typical Korean spider assemblage. The temporal patterns of spider species richness and spider abundance were very similar between Bt and non-Bt rice, although significant differences in species richness were observed on a few occasions. Overall, spider community structure, including diversity, the dominant species, and abundance did not differ between Bt and non-Bt rice. The results of the study indicated that the transgenic Cry1Ac rice lines tested in this study had no adverse effects on the spider community structure of the rice fields.

  4. Functional Group of Spiders in Cultivated Landscape Dominated by Paddy Fields in West Java, Indonesia

    I WAYAN SUANA

    2009-03-01

    Full Text Available Distribution of spiders in all colonized environments is limited by biotic and abiotic factors requiring adaptations with respect to, for example microhabitat choice and hunting behavior. These two factors were frequently used to group spiders into functional groups. In this study our objectives were to (i group of genera of spiders into functional group based on their microhabitat specificity, hunting behavior, and daily activity; and (ii compare the number and composition of functional group of spider at each habitat type and period of paddy growth. The study was conducted at a landscape dominated by paddy fields in Cianjur Watershed for a period of 9 months. Four different habitat types (paddy, vegetable, non-crop, and mixed garden, were sampled using five trapping techniques (pitfall traps, farmcop suction, sweep netting, yellow-pan traps, and sticky traps. The Unweighted Pair-Group Average and the Euclidean Distances were used to generate dendrogram of functional group of spider. We found 14 functional groups of spider at genus level. The number of functional group of spider at four habitat types was differing, but the composition was similar, because all habitats were closed to each other. Habitat structure diversity and disturbance level influenced the number of functional group of spider. Different architecture of vegetation and availability of differ prey during paddy growth, causing the composition of functional group of spider in each period of paddy growth was changed, although its number was unchanged.

  5. A novel probe density controllable electrochemiluminescence biosensor for ultra-sensitive detection of Hg2+ based on DNA hybridization optimization with gold nanoparticles array patterned self-assembly platform.

    Gao, Wenhua; Zhang, An; Chen, Yunsheng; Chen, Zixuan; Chen, Yaowen; Lu, Fushen; Chen, Zhanguang

    2013-11-15

    Biosensor based on DNA hybridization holds great potential to get higher sensitivity as the optimal DNA hybridization efficiency can be achieved by controlling the distribution and orientation of probe strands on the transducer surface. In this work, an innovative strategy is reported to tap the sensitivity potential of current electrochemiluminescence (ECL) biosensing system by dispersedly anchoring the DNA beacons on the gold nanoparticles (GNPs) array which was electrodeposited on the glassy carbon electrode surface, rather than simply sprawling the coil-like strands onto planar gold surface. The strategy was developed by designing a "signal-on" ECL biosensing switch fabricated on the GNPs nanopatterned electrode surface for enhanced ultra-sensitivity detection of Hg(2+). A 57-mer hairpin-DNA labeled with ferrocene as ECL quencher and a 13-mer DNA labeled with Ru(bpy)3(2+) as reporter were hybridized to construct the signal generator in off-state. A 31-mer thymine (T)-rich capture-DNA was introduced to form T-T mismatches with the loop sequence of the hairpin-DNA in the presence of Hg(2+) and induce the stem-loop open, meanwhile the ECL "signal-on" was triggered. The peak sensitivity with the lowest detection limit of 0.1 nM was achieved with the optimal GNPs number density while exorbitant GNPs deposition resulted in sensitivity deterioration for the biosensor. We expect the present strategy could lead the renovation of the existing probe-immobilized ECL genosensor design to get an even higher sensitivity in ultralow level of target detection such as the identification of genetic diseases and disorders in basic research and clinical application. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Identification and Biochemical Properties of Two New Acetylcholinesterases in the Pond Wolf Spider (Pardosa pseudoannulata.

    Xiangkun Meng

    Full Text Available Acetylcholinesterase (AChE, an important neurotransmitter hydrolase in both invertebrates and vertebrates, is targeted by organophosphorus and carbamate insecticides. In this study, two new AChEs were identified in the pond wolf spider Pardosa pseudoannulata, an important predatory natural enemy of several insect pests. In total, four AChEs were found in P. pseudoannulata (including two AChEs previously identified in our laboratory. The new putative AChEs PpAChE3 and PpAChE4 contain most of the common features of the AChE family, including cysteine residues, choline binding sites, the conserved sequence 'FGESAG' and conserved aromatic residues but with a catalytic triad of 'SDH' rather than 'SEH'. Recombinant enzymes expressed in Sf9 cells showed significant differences in biochemical properties compared to other AChEs, such as the optimal pH, substrate specificity, and catalytic efficiency. Among three test substrates, PpAChE1, PpAChE3 and PpAChE4 showed the highest catalytic efficiency (Vmax/KM for ATC (acetylthiocholine iodide, with PpAChE3 exhibiting a clear preference for ATC based on the VmaxATC/VmaxBTC ratio. In addition, the four PpAChEs were more sensitive to the AChE-specific inhibitor BW284C51, which acts against ATC hydrolysis, than to the BChE-specific inhibitor ISO-OMPA, which acts against BTC hydrolysis, with at least a 8.5-fold difference in IC50 values for each PpAChE. PpAChE3, PpAChE4, and PpAChE1 were more sensitive than PpAChE2 to the tested Carb insecticides, and PpAChE3 was more sensitive than the other three AChEs to the tested OP insecticides. Based on all the results, two new functional AChEs were identified from P. pseudoannulata. The differences in AChE sequence between this spider and insects enrich our knowledge of invertebrate AChE diversity, and our findings will be helpful for understanding the selectivity of insecticides between insects and natural enemy spiders.

  7. Spider-mediated flux of PCBs from contaminated sediments to terrestrial ecosystems and potential risks to arachnivorous birds

    We investigated aquatic insect utilization and PCB exposure in riparian spiders at the Lake Hartwell superfund site (Clemson, SC , USA). We sampled sediments, adult chironomids, terrestrial insects, riparian spiders (Tetragnathidae, Araneidae, and Mecynogea lemniscata), and upla...

  8. Battre sa (super) coulpe : Spider-Man (1962)

    Tomasovic, Dick

    2016-01-01

    L’édification est l'une des grandes fonctions traditionnelles de la littérature de jeunesse. Spider-Man, héros populaire s'il en est, s'est révélé bien sûr l'ambassadeur de nombreuses valeurs sociétales américaines (le do it yourself, l'esprit d'entreprise et d'indépendance, la tolérance, la fidélité , la célébration du système éducationnel, la transmission et la solidarité intergénérationnelle, le sens des responsabilités, évidemment, etc.). Spider-Man se bat moins qu'il ne se débat. Il est ...

  9. A Spider That Lays Its Eggs in Rows

    Robert L. Edwards

    2000-01-01

    Full Text Available The small (2.5-3.0 mm, colorful metine spider, Homalometa nigritarsis Simon 1897, Family Tetragnathidae, has previously been reported from northern Mexico, Panama and the southern islands of the Lesser Antilles (Levi 1986. In the rain forest of northeastern Puerto Rico it is most frequently found with webbing on the larger outer concave surfaces of pendulous leaves. H. nigritarsis typically makes a circular, relatively flat retreat within which the female deposits two parallel rows of naked eggs. The rows are produced at intervals; as one row hatches another replaces it shortly thereafter. Evidence of up to four generations of rows has been observed. Above the retreat, and closely aligned with it, the spider builds a nearly invisible, delicate orb web, typically from edge to edge of the leaf (Fig. 1a and b. While retaining the traditional orb-web, H. nigritarsis has adopted a unique habitat and set of life history features.

  10.  “Spiders and Webs in American Literature”

    Vincent Dussol

    2012-05-01

    Full Text Available From Jonathan Edwards to Jorie Graham, spiders are strikingly present in American literature. The purpose of this article is first to show how that theme may have become something of a national tradition as very different writers, all of them careful observers of aranae, answered one another through the years. It is very likely that the attention paid to spiders by American authors was increased by those Native American myths in which spiders are a central figure. More than occasionally, on the female side of the American counter-culture, especially among its feminist and lesbian exponents, simple activists and creative writers have harnessed the symbolic power invested in the spider by Native Americans.There may be deeper reasons accounting for American authors’ fascination with spiders. The country’s phobia of disunion is one; a nation of settlers’ acute consciousness of the precariousness of its occupation of the territory is another. In demonstrating outstanding skills for adjustment to unknown places, spiders epitomize a form of identity permanence. The predominantly positive character of spider symbols in American literature will occasionally be inverted. Following the national logic of checks and balances, any web covering the whole of the United States will tend to come under suspicion.This study ends with an inventory of cultural productions linked with spiders and webs and whose Americanness is yet to be clearly determined.De Jonathan Edwards à Jorie Graham, l’araignée apparaît dans un nombre frappant de textes littéraires américains. On a d’abord voulu tenter de montrer comment a pu se construire cette tradition thématique et faire la preuve que différents écrivains, réunis par un souci de l’observation, se sont répondus à travers elle. L’attention prêtée à l’araignée s’est certainement trouvée renforcée par les récits mythologiques des peuples premiers américains qui font de l’araignée une

  11. Gravity Reception and Cardiac Function in the Spider

    Finck, A.

    1985-01-01

    The following features of the arachnid gravity system were studied. (1) the absolute threshold to hyper-gz is quite low indicating fine proprioreceptive properties of the lyriform organ, the Gz/vibration detector; (2) the neurogenic heart of the spider is a good dependent variable for assessing its behavior to Gz and other stimuli which produce mechanical effects on the exoskeleton; (3) Not only is the cardiac response useful but it is now understood to be an integral part of the system which compensates for the consequences of gravity in the spider (an hydraulic leg extension); and (4) a theoretical model was proposed in which a mechanical amplifier, the leg lever, converts a weak force (at the tarsus) to a strong force (at the patella), capable of compressing the exoskeleton and consequently the lyriform receptor.

  12. Environmental Engineering Approaches toward Sustainable Management of Spider Mites.

    Suzuki, Takeshi

    2012-10-26

    Integrated pest management (IPM), which combines physical, biological, and chemical control measures to complementary effect, is one of the most important approaches to environmentally friendly sustainable agriculture. To expand IPM, we need to develop new pest control measures, reinforce existing measures, and investigate interactions between measures. Continued progress in the development of environmental control technologies and consequent price drops have facilitated their integration into plant production and pest control. Here I describe environmental control technologies for the IPM of spider mites through: (1) the disturbance of photoperiod-dependent diapause by artificial light, which may lead to death in seasonal environments; (2) the use of ultraviolet radiation to kill or repel mites; and (3) the use of water vapor control for the long-term cold storage of commercially available natural enemies. Such environmental control technologies have great potential for the efficient control of spider mites through direct physical effects and indirect effects via natural enemies.

  13. Prey capture by the crab spider Misumena calycina (Araneae: Thomisidae).

    Morse, Douglass H

    1979-01-01

    Crab spiders Misumena calycina (L.) in pasture rose Rosa carolina flowers regularly attacked bumble bees, smaller bees, and syrphid flies that visited these flowers. Attacks reached a maximum rate of over 20/h during mid morning, but only 1.6% of the most important prey item, bumble bees, were captured. The next most important food source, the most frequently taken item, syrphid flies Toxomerus marginatus (Say), were captured in 39% of the attempts. Since these flies have a biomass only 1/60th that of bumble bees, they comprised a much less important food source than did bumble bees. Spiders would obtain over 7% more food by specializing on bumble bees than by attacking all insect visitors, and as much as 20% more food at certain times of the day. However, they did not show a tendency to specialize at any time.

  14. Spatial distribution of Madeira Island Laurisilva endemic spiders (Arachnida: Araneae)

    2014-01-01

    Abstract Madeira island presents a unique spider diversity with a high number of endemic species, many of which are still poorly known. A recent biodiversity survey on the terrestrial arthropods of the native forest, Laurisilva, provided a large set of standardized samples from various patches throughout the island. Out of the fifty two species recorded, approximately 33.3% are Madeiran endemics, many of which had not been collected since their original description. Two new species to science are reported – Ceratinopsis n. sp. and Theridion n. sp. – and the first records of Poeciloneta variegata (Blackwall, 1841) and Tetragnatha intermedia Kulczynski, 1891 are reported for the first time for Madeira island. Considerations on species richness and abundance from different Laurisilva locations are presented, together with distribution maps for endemic species. These results contribute to a better understanding of spider diversity patterns and endemic species distribution in the native forest of Madeira island. PMID:24855443

  15. Structure to function: Spider silk and human collagen

    Rabotyagova, Olena S.

    Nature has the ability to assemble a variety of simple molecules into complex functional structures with diverse properties. Collagens, silks and muscles fibers are some examples of fibrous proteins with self-assembling properties. One of the great challenges facing Science is to mimic these designs in Nature to find a way to construct molecules that are capable of organizing into functional supra-structures by self-assembly. In order to do so, a construction kit consisting of molecular building blocks along with a complete understanding on how to form functional materials is required. In this current research, the focus is on spider silk and collagen as fibrous protein-based biopolymers that can shed light on how to generate nanostructures through the complex process of self-assembly. Spider silk in fiber form offers a unique combination of high elasticity, toughness, and mechanical strength, along with biological compatibility and biodegrability. Spider silk is an example of a natural block copolymer, in which hydrophobic and hydrophilic blocks are linked together generating polymers that organize into functional materials with extraordinary properties. Since silks resemble synthetic block copolymer systems, we adopted the principles of block copolymer design from the synthetic polymer literature to build block copolymers based on spider silk sequences. Moreover, we consider spider silk to be an important model with which to study the relationships between structure and properties in our system. Thus, the first part of this work was dedicated to a novel family of spider silk block copolymers, where we generated a new family of functional spider silk-like block copolymers through recombinant DNA technology. To provide fundamental insight into relationships between peptide primary sequence, block composition, and block length and observed morphological and structural features, we used these bioengineered spider silk block copolymers to study secondary structure

  16. Hamiltonian Dynamics of Spider-Type Multirotor Rigid Bodies Systems

    Doroshin, Anton V.

    2010-01-01

    This paper sets out to develop a spider-type multiple-rotor system which can be used for attitude control of spacecraft. The multirotor system contains a large number of rotor-equipped rays, so it was called a 'Spider-type System', also it can be called 'Rotary Hedgehog'. These systems allow using spinups and captures of conjugate rotors to perform compound attitude motion of spacecraft. The paper describes a new method of spacecraft attitude reorientation and new mathematical model of motion in Hamilton form. Hamiltonian dynamics of the system is investigated with the help of Andoyer-Deprit canonical variables. These variables allow obtaining exact solution for hetero- and homoclinic orbits in phase space of the system motion, which are very important for qualitative analysis.

  17. VIPR III VADR SPIDER Structural Design and Analysis

    Li, Wesley; Chen, Tony

    2016-01-01

    In support of the National Aeronautics and Space Administration (NASA) Vehicle Integrated Propulsion Research (VIPR) Phase III team to evaluate the volcanic ash environment effects on the Pratt & Whitney F117-PW-100 turbofan engine, NASA Armstrong Flight Research Center has successfully performed structural design and analysis on the Volcanic Ash Distribution Rig (VADR) and the Structural Particulate Integration Device for Engine Research (SPIDER) for the ash ingestion test. Static and dynamic load analyses were performed to ensure no structural failure would occur during the test. Modal analysis was conducted, and the results were used to develop engine power setting avoidance zones. These engine power setting avoidance zones were defined to minimize the dwell time when the natural frequencies of the VADR/SPIDER system coincided with the excitation frequencies of the engine which was operating at various revolutions per minute. Vortex-induced vibration due to engine suction air flow during the ingestion test was also evaluated, but was not a concern.

  18. [Transcatheter embolization for huge pulmonary arteriovenous fistula using metallic "spider" and spring embolus--application of hand-made metallic "spider" using partial monorail technique].

    Hirota, S; Sako, M; Fujita, Y; Hasegawa, Y; Sugimoto, K; Suzuki, Y; Kono, M

    1992-07-25

    We performed transcatheter embolization in two cases with huge pulmonary arteriovenous fistula (AVF) using a metallic "spider" and spring embolus. Conventional spring embolus or detachable balloon could not be used in these cases. Metallic spider was indicated for pulmonary AVF with a feeding artery diameter of more than 16 mm to prevent embolus passing through the AVF. In the first case, we used large handmade metallic spiders of 25 mm in diameter followed by embolization by numerous spring coils. At that time, a partial monorail technique was newly devised to carry the large metallic spider into the feeding artery, otherwise the spider could not pass into a 9F catheter. After embolization, symptoms and PaO2 in arterial blood improved remarkably in both cases. In the second case, a spring coil migrated into the normal pulmonary artery, but no infarction resulted. In conclusion, the metallic spider was very useful for embolization of hugee pulmonary AVF to avoid the embolus passing through and to tangle spring coils together with it. If commercially available "spiders" are too small, ones can be made easily.

  19. Plant integration of MITICA and SPIDER experiments with auxiliary plants and buildings on PRIMA site

    Fellin, Francesco, E-mail: francesco.fellin@igi.cnr.it; Boldrin, Marco; Zaccaria, Pierluigi; Agostinetti, Piero; Battistella, Manuela; Bigi, Marco; Palma, Samuele Dal Bello Mauro Dalla; Fiorentin, Aldo; Luchetta, Adriano; Maistrello, Alberto; Marcuzzi, Diego; Ocello, Edoardo; Pasqualotto, Roberto; Pavei, Mauro; Pomaro, Nicola; Rizzolo, Andrea; Toigo, Vanni; Valente, Matteo; Zanotto, Loris; Calore, Luca; and others

    2015-10-15

    Highlights: • Focus on plant integration work supporting the realization of SPIDER and MITICA fusion experiments hosted in PRIMA buildings complex in Padova, Italy. • Huge effort of coordination and integration among many stakeholders, taking into account several constrains coming from experiments requirements (on-going) and precise time schedule and budget on buildings construction. • The paper also deals of interfaces management, coordination and integration of many competences, problems solving to find best solution also considering other aspects like safety and maintenance. - Abstract: This paper presents a description of the PRIMA (Padova Research on ITER Megavolt Accelerator) Plant Integration work, aimed at the construction of PRIMA Buildings, which will host two nuclear fusion test facilities named SPIDER and MITICA, finalized to test and optimize the neutral beam injectors for ITER experiment. These activities are very complex: inputs coming from the experiments design are changing time to time, while the buildings construction shall fulfill precise time schedule and budget. Moreover the decision process is often very long due to the high number of stakeholders (RFX, IO, third parties, suppliers, domestic agencies from different countries). The huge effort includes: forecasting what will be necessary for the integration of many experimental plants; collecting requirements and translating into inputs; interfaces management; coordination meetings with hundreds of people with various and different competences in construction and operation of fusion facilities, thermomechanics, electrical and control, buildings design and construction (civil plants plus architectural and structural aspects), safety, maintenance and management. The paper describes these activities and also the tools created to check and to validate the building design, to manage the interfaces and the organization put in place to achieve the required targets.

  20. Spider silk constructs enhance axonal regeneration and remyelination in long nerve defects in sheep.

    Christine Radtke

    Full Text Available BACKGROUND: Surgical reapposition of peripheral nerve results in some axonal regeneration and functional recovery, but the clinical outcome in long distance nerve defects is disappointing and research continues to utilize further interventional approaches to optimize functional recovery. We describe the use of nerve constructs consisting of decellularized vein grafts filled with spider silk fibers as a guiding material to bridge a 6.0 cm tibial nerve defect in adult sheep. METHODOLOGY/PRINCIPAL FINDINGS: The nerve constructs were compared to autologous nerve grafts. Regeneration was evaluated for clinical, electrophysiological and histological outcome. Electrophysiological recordings were obtained at 6 months and 10 months post surgery in each group. Ten months later, the nerves were removed and prepared for immunostaining, electrophysiological and electron microscopy. Immunostaining for sodium channel (NaV 1.6 was used to define nodes of Ranvier on regenerated axons in combination with anti-S100 and neurofilament. Anti-S100 was used to identify Schwann cells. Axons regenerated through the constructs and were myelinated indicating migration of Schwann cells into the constructs. Nodes of Ranvier between myelin segments were observed and identified by intense sodium channel (NaV 1.6 staining on the regenerated axons. There was no significant difference in electrophysiological results between control autologous experimental and construct implantation indicating that our construct are an effective alternative to autologous nerve transplantation. CONCLUSIONS/SIGNIFICANCE: This study demonstrates that spider silk enhances Schwann cell migration, axonal regrowth and remyelination including electrophysiological recovery in a long-distance peripheral nerve gap model resulting in functional recovery. This improvement in nerve regeneration could have significant clinical implications for reconstructive nerve surgery.

  1. Plant integration of MITICA and SPIDER experiments with auxiliary plants and buildings on PRIMA site

    Fellin, Francesco; Boldrin, Marco; Zaccaria, Pierluigi; Agostinetti, Piero; Battistella, Manuela; Bigi, Marco; Palma, Samuele Dal Bello Mauro Dalla; Fiorentin, Aldo; Luchetta, Adriano; Maistrello, Alberto; Marcuzzi, Diego; Ocello, Edoardo; Pasqualotto, Roberto; Pavei, Mauro; Pomaro, Nicola; Rizzolo, Andrea; Toigo, Vanni; Valente, Matteo; Zanotto, Loris; Calore, Luca

    2015-01-01

    Highlights: • Focus on plant integration work supporting the realization of SPIDER and MITICA fusion experiments hosted in PRIMA buildings complex in Padova, Italy. • Huge effort of coordination and integration among many stakeholders, taking into account several constrains coming from experiments requirements (on-going) and precise time schedule and budget on buildings construction. • The paper also deals of interfaces management, coordination and integration of many competences, problems solving to find best solution also considering other aspects like safety and maintenance. - Abstract: This paper presents a description of the PRIMA (Padova Research on ITER Megavolt Accelerator) Plant Integration work, aimed at the construction of PRIMA Buildings, which will host two nuclear fusion test facilities named SPIDER and MITICA, finalized to test and optimize the neutral beam injectors for ITER experiment. These activities are very complex: inputs coming from the experiments design are changing time to time, while the buildings construction shall fulfill precise time schedule and budget. Moreover the decision process is often very long due to the high number of stakeholders (RFX, IO, third parties, suppliers, domestic agencies from different countries). The huge effort includes: forecasting what will be necessary for the integration of many experimental plants; collecting requirements and translating into inputs; interfaces management; coordination meetings with hundreds of people with various and different competences in construction and operation of fusion facilities, thermomechanics, electrical and control, buildings design and construction (civil plants plus architectural and structural aspects), safety, maintenance and management. The paper describes these activities and also the tools created to check and to validate the building design, to manage the interfaces and the organization put in place to achieve the required targets.

  2. A troglomorphic spider from Java (Araneae, Ctenidae, Amauropelma)

    Miller, Jeremy; Rahmadi, Cahyo

    2012-01-01

    Abstract A new troglomorphic spider from caves in Central Java, Indonesia, is described and placed in the ctenid genus Amauropelma Raven, Stumkat & Gray, until now containing only species from Queensland, Australia. Only juveniles and mature females of the new species are known. We give our reasons for placing the new species in Amauropelma, discuss conflicting characters, and make predictions about the morphology of the as yet undiscovered male that will test our taxonomic hypothesis. The description includes DNA barcode sequence data. PMID:22303127

  3. Signal conflict in spider webs driven by predators and prey

    Blackledge, T. A.

    1998-01-01

    Variation in the sensory physiologies of organisms can bias the receptions of signals, driving the direction of signal evolution. Sensory drive in the evolution of signals may be particularly important for organisms that confront trade-offs in signal design between the need for conspicuousness to allow effective transfer of information and the need for crypsis of the signal to unintended receivers. Several genera of orb-weaving spiders include conspicuous silk designs, stabilimenta, in the ce...

  4. On the colours of spider orb-webs

    Suhr, Wilfried; Schlichting, H Joachim, E-mail: wilfried.suhr@uni-muenster.de, E-mail: schlichting@uni-muenster.de [Institut fuer Didaktik der Physik, University of Muenster, 48149 Muenster (Germany)

    2011-03-15

    A sticky capture thread from the spiral element of spider orb-webs is formed of almost regularly spaced droplets that surround a supporting axial fibre. From the perspective of physical optics it represents a periodic linear array of scattering elements that acts as a diffraction grating. This is a novel aspect, which is of vital importance for the understanding of the overall scattering pattern. To demonstrate its significance, we present our experimental findings and compare them with results of a simplified model.

  5. The effect of age on encounters between male crab spiders

    Helen H. Hu; Douglass H. Morse

    2004-01-01

    In males that compete aggressively for females, size and age may determine which males obtain access to these females. In the present study, we use the crab spider, Misumena vatia, a species with males that do not grow after becoming sexually mature adults, to test the hypothesis that age affects the success of males competing for access to females. M. vatia is an excellent species to test this hypothesis because it is possible to disentangle age from size, characters that typically vary toge...

  6. Antenna-coupled TES bolometers for the SPIDER experiment

    Kuo, C.L. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)]|[California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 (United States)]. E-mail: clkuo@astro.caltech.edu; Ade, P. [University of Wales, Cardiff, 5 The Parade, Cardiff, CF24 3YB, Wales (United Kingdom); Bock, J.J. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)]|[California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 (United States); Day, P. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)]|[California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 (United States); Goldin, A.; Golwala, S.; Hristov, V.; Jones, W.C.; Lange, A.E.; Rossinot, P.; Vayonakis, A.; Wang, G. [California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 (United States); Halpern, M. [University of British Columbia, 2329 West Mall, Vancouver, BC, V6T 1Z4 (Canada); Hilton, G.; Irwin, K. [National Institute of Standards and Technology, 325 Broadway, Boulder, CO (United States); Holmes, W.; Kenyon, M.; LeDuc, H.G. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); MacTavish, C. [University of Toronto, 60 St. George Street, Toronto, ON, M5S 1A7 (Canada); Montroy, T.; Ruhl, J. [Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106 (United States); Netterfield, C.B. [University of Toronto, 60 St. George Street, Toronto, ON, M5S 1A7 (Canada); Yun, M. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)]|[University of Pittsburgh, 348 Benedum Engineering Hall, Pittsburgh, PA 15261 (United States); Zmuidzinas, J. [Jet Propulsion Laboratory, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)]|[California Institute of Technology, 1200 E California Boulevard, Pasadena, CA 91125 (United States)

    2006-04-15

    SPIDER is a proposed balloon-borne experiment designed to search for the imprints of gravity waves on the polarization of the cosmic microwave background radiation. The required wide frequency coverage, large number of sensitive detectors, and the stringent power constraints on a balloon are made possible by antenna-coupled TES bolometers. Several prototype devices have been fabricated and optically characterized. Their spectral and angular responses agree well with the theoretical expectations.

  7. Innate pattern recognition and categorization in a jumping spider.

    Yinnon Dolev

    Full Text Available The East African jumping spider Evarcha culicivora feeds indirectly on vertebrate blood by preferentially preying upon blood-fed Anopheles mosquitoes, the vectors of human malaria1, using the distinct resting posture and engorged abdomen characteristic of these specific prey as key elements for their recognition. To understand perceptual categorization of objects by these spiders, we investigated their predatory behavior toward different digital stimuli--abstract 'stick figure' representations of Anopheles constructed solely by known key identification elements, disarranged versions of these, as well as non-prey items and detailed images of alternative prey. We hypothesized that the abstract images representing Anopheles would be perceived as potential prey, and would be preferred to those of non-preferred prey. Spiders perceived the abstract stick figures of Anopheles specifically as their preferred prey, attacking them significantly more often than non-preferred prey, even when the comprising elements of the Anopheles stick figures were disarranged and disconnected from each other. However, if the relative angles between the elements of the disconnected stick figures of Anopheles were altered, the otherwise identical set of elements was no longer perceived as prey. These data show that E. culicivora is capable of making discriminations based on abstract concepts, such as the hypothetical angle formed by discontinuous elements. It is this inter-element angle rather than resting posture that is important for correct identification of Anopheles. Our results provide a glimpse of the underlying processes of object recognition in animals with minute brains, and suggest that these spiders use a local processing approach for object recognition, rather than a holistic or global approach. This study provides an excellent basis for a comparative analysis on feature extraction and detection by animals as diverse as bees and mammals.

  8. Reproductive Seasonality in Nesticus (Araneae: Nesticidae) Cave Spiders.

    Carver, Linnea M; Perlaky, Patricia; Cressler, Alan; Zigler, Kirk S

    2016-01-01

    Spiders of the family Nesticidae are members of cave communities around the world with cave-obligate (troglobiotic) species known from North America, Europe, Asia and the Indo-Pacific. A radiation of Nesticus (Araneae: Nesticidae) in the southern Appalachians includes ten troglobiotic species. Many of these species are of conservation interest due to their small ranges, with four species being single-cave endemics. Despite conservation concerns and their important role as predators in cave communities, we know little about reproduction and feeding in this group. We addressed this knowledge gap by examining populations of two species on a monthly basis for one year. We made further observations on several other species and populations, totaling 671 individual spider observations. This more than doubled the reported observations of reproduction and feeding in troglobiotic Nesticus. Female Nesticus carry egg sacs, facilitating the determination of the timing and frequency of reproduction. We found that Nesticus exhibit reproductive seasonality. Females carried egg sacs from May through October, with a peak in frequency in June. These spiders were rarely observed with prey; only 3.3% (22/671) of individuals were observed with prey items. The frequency at which prey items were observed did not vary by season. Common prey items were flies, beetles and millipedes. Troglobiotic species constituted approximately half of all prey items observed. This result represents a greater proportion of troglobiotic prey than has been reported for various troglophilic spiders. Although our findings shed light on the life history of troglobiotic Nesticus and on their role in cave ecosystems, further work is necessary to support effective conservation planning for many of these rare species.

  9. Spiders in mountain habitats of the Giant Mountains

    Růžička, Vlastimil; Vaněk, J.; Šmilauer, P.

    2012-01-01

    Roč. 43, č. 4 (2012), s. 341-347 ISSN 1067-4136 Institutional research plan: CEZ:AV0Z50070508 Keywords : Giant Mountains (Krkonoše, Karkonosze) * spider s * anemo-orographic systems Subject RIV: EH - Ecology, Behaviour Impact factor: 0.236, year: 2012 http://www.springerlink.com/content/0k5g721q1155r146/fulltext.pdf

  10. Innate Pattern Recognition and Categorization in a Jumping Spider

    Dolev, Yinnon; Nelson, Ximena J.

    2014-01-01

    The East African jumping spider Evarcha culicivora feeds indirectly on vertebrate blood by preferentially preying upon blood-fed Anopheles mosquitoes, the vectors of human malaria1, using the distinct resting posture and engorged abdomen characteristic of these specific prey as key elements for their recognition. To understand perceptual categorization of objects by these spiders, we investigated their predatory behavior toward different digital stimuli - abstract ‘stick figure’ representations of Anopheles constructed solely by known key identification elements, disarranged versions of these, as well as non-prey items and detailed images of alternative prey. We hypothesized that the abstract images representing Anopheles would be perceived as potential prey, and would be preferred to those of non-preferred prey. Spiders perceived the abstract stick figures of Anopheles specifically as their preferred prey, attacking them significantly more often than non-preferred prey, even when the comprising elements of the Anopheles stick figures were disarranged and disconnected from each other. However, if the relative angles between the elements of the disconnected stick figures of Anopheles were altered, the otherwise identical set of elements was no longer perceived as prey. These data show that E. culicivora is capable of making discriminations based on abstract concepts, such as the hypothetical angle formed by discontinuous elements. It is this inter-element angle rather than resting posture that is important for correct identification of Anopheles. Our results provide a glimpse of the underlying processes of object recognition in animals with minute brains, and suggest that these spiders use a local processing approach for object recognition, rather than a holistic or global approach. This study provides an excellent basis for a comparative analysis on feature extraction and detection by animals as diverse as bees and mammals. PMID:24893306

  11. On the colours of spider orb-webs

    Suhr, Wilfried; Schlichting, H Joachim

    2011-01-01

    A sticky capture thread from the spiral element of spider orb-webs is formed of almost regularly spaced droplets that surround a supporting axial fibre. From the perspective of physical optics it represents a periodic linear array of scattering elements that acts as a diffraction grating. This is a novel aspect, which is of vital importance for the understanding of the overall scattering pattern. To demonstrate its significance, we present our experimental findings and compare them with results of a simplified model.

  12. Colonization of subterranean habitats by spiders in Central Europe

    Růžička, Vlastimil; Šmilauer, P.; Mlejnek, R.

    2013-01-01

    Roč. 42, č. 2 (2013), s. 133-140 ISSN 0392-6672 Grant - others:GA JU(CZ) GAJU 04-142/2010/P Institutional support: RVO:60077344 Keywords : superficial and deep subterranean habitats * caves * spider s Subject RIV: EH - Ecology, Behaviour Impact factor: 1.275, year: 2013 http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=1288&context=ijs

  13. Early environmental conditions shape personality types in a jumping spider

    Jannis eLiedtke

    2015-12-01

    Full Text Available Individuals of many species across the animal kingdom are found to be less plastic than expected, even in behavioral traits. The existence of consistent behavioral differences between individuals, termed personality differences, is puzzling, since plastic behavior is considered ideal to enable animals to adaptively respond to changes in environmental conditions. In order to elucidate which mechanisms are important for the evolution of personality differences, it is crucial to understand which aspects of the environment are important for the development of personality differences. Here, we tested whether physical or social aspects of the environment during development influence individual differentiation (mean level of behavior using the jumping spider Marpissa muscosa. Furthermore, we assessed whether those behaviors were repeatable, i.e. whether personalities existed. We applied a split-brood design and raised spider siblings in three different environments: a deprived environment with no enrichment, a socially and a physically enriched environment. We focused on exploratory behavior and repeatedly assessed individual behavior in a novel environment and a novel object test. Results show that the environment during development influenced spiders’ exploratory tendencies: spiders raised in enriched environments tended to be more exploratory. Most investigated behaviors were repeatable (i.e. personalities existed across all individuals tested, whereas only few behaviors were also repeatable across individuals that had experienced the same environmental condition. Taken together, our results indicate that external stimuli can influence the development of one aspect of personality, the inter-individual variation (mean level of behavior, in a jumping spider. We also found family by environment interactions on behavioral traits potentially suggesting genetic variation in developmental plasticity.

  14. Einstein Inflationary Probe (EIP)

    Hinshaw, Gary

    2004-01-01

    I will discuss plans to develop a concept for the Einstein Inflation Probe: a mission to detect gravity waves from inflation via the unique signature they impart to the cosmic microwave background (CMB) polarization. A sensitive CMB polarization satellite may be the only way to probe physics at the grand-unified theory (GUT) scale, exceeding by 12 orders of magnitude the energies studied at the Large Hadron Collider. A detection of gravity waves would represent a remarkable confirmation of the inflationary paradigm and set the energy scale at which inflation occurred when the universe was a fraction of a second old. Even a strong upper limit to the gravity wave amplitude would be significant, ruling out many common models of inflation, and pointing to inflation occurring at much lower energy, if at all. Measuring gravity waves via the CMB polarization will be challenging. We will undertake a comprehensive study to identify the critical scientific requirements for the mission and their derived instrumental performance requirements. At the core of the study will be an assessment of what is scientifically and experimentally optimal within the scope and purpose of the Einstein Inflation Probe.

  15. A New Limit on CMB Circular Polarization from SPIDER

    Nagy, J. M.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, H. C.; Contaldi, C. R.; Doré, O.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fissel, L. M.; Fraisse, A. A.; Freese, K.; Galloway, M.; Gambrel, A. E.; Gandilo, N. N.; Ganga, K.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; Kermish, Z. D.; Li, S.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Netterfield, C. B.; Nolta, M.; Padilla, I. L.; Racine, B.; Rahlin, A. S.; Reintsema, C.; Ruhl, J. E.; Runyan, M. C.; Ruud, T. M.; Shariff, J. A.; Soler, J. D.; Song, X.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; Van Der List, J. F.; Weber, A. C.; Wehus, I. K.; Wiebe, D. V.; Young, E. Y.

    2017-08-01

    We present a new upper limit on cosmic microwave background (CMB) circular polarization from the 2015 flight of Spider, a balloon-borne telescope designed to search for B-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the nonzero circular-to-linear polarization coupling of the half-wave plate polarization modulators, data from Spider's 2015 Antarctic flight provide a constraint on Stokes V at 95 and 150 GHz in the range 33< {\\ell }< 307. No other limits exist over this full range of angular scales, and Spider improves on the previous limit by several orders of magnitude, providing 95% C.L. constraints on {\\ell }({\\ell }+1){C}{\\ell }{VV}/(2π ) ranging from 141 to 255 μK2 at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain even stronger constraints on circular polarization.

  16. A New Limit on CMB Circular Polarization from SPIDER

    Nagy, J. M.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, H. C.; Contaldi, C. R.; Doré, O.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fissel, L. M.; Fraisse, A. A.; Freese, K.; Galloway, M.; Gambrel, A. E.; Gandilo, N. N.; Ganga, K.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; Kermish, Z. D.; Li, S.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Netterfield, C. B.; Nolta, M.; Padilla, I. L.; Racine, B.; Rahlin, A. S.; Reintsema, C.; Ruhl, J. E.; Runyan, M. C.; Ruud, T. M.; Shariff, J. A.; Soler, J. D.; Song, X.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; List, J. F. Van Der; Weber, A. C.; Wehus, I. K.; Wiebe, D. V.; Young, E. Y.

    2017-08-01

    We present a new upper limit on CMB circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for $B$-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the non-zero circular-to-linear polarization coupling of the HWP polarization modulators, data from SPIDER's 2015 Antarctic flight provides a constraint on Stokes $V$ at 95 and 150 GHz from $33<\\ell<307$. No other limits exist over this full range of angular scales, and SPIDER improves upon the previous limit by several orders of magnitude, providing 95% C.L. constraints on $\\ell (\\ell+1)C_{\\ell}^{VV}/(2\\pi)$ ranging from 141 $\\mu K ^2$ to 203 $\\mu K ^2$ at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain stronger constraints on circular polarization.

  17. Detail design of the beam source for the SPIDER experiment

    Marcuzzi, D.; Agostinetti, P.; Dalla Palma, M.; Degli Agostini, F.; Pavei, M.; Rizzolo, A.; Tollin, M.; Trevisan, L.

    2010-01-01

    The ITER Neutral Beam Test Facility (PRIMA-Padova Research on Injector Megavolt Accelerated) is planned to be built at Consorzio RFX (Padova, Italy). PRIMA includes two experimental devices: a full size plasma source with low voltage extraction called SPIDER (Source for Production of Ion of Deuterium Extracted from RF plasma) and a full size neutral beam injector at full beam power called MITICA (Megavolt ITER Injector Concept Advancement). SPIDER is the first experimental device to be built and operated, aiming at testing the extraction of a negative ion beam (made of H - and in a later stage D - ions) from an ITER size ion source. The main requirements of this experiment are a H - /D - current of approximately 70 A/50 A and an energy of 100 keV. This paper presents an overview of the SPIDER beam source design, with a particular focus on the main design choices, aiming at reaching the best compromise between physics, optics, thermo-mechanical, cooling, assembly and electrical requirements.

  18. Jewelled spiders manipulate colour-lure geometry to deceive prey.

    White, Thomas E

    2017-03-01

    Selection is expected to favour the evolution of efficacy in visual communication. This extends to deceptive systems, and predicts functional links between the structure of visual signals and their behavioural presentation. Work to date has primarily focused on colour, however, thereby understating the multicomponent nature of visual signals. Here I examined the relationship between signal structure, presentation behaviour, and efficacy in the context of colour-based prey luring. I used the polymorphic orb-web spider Gasteracantha fornicata , whose yellow- or white-and-black striped dorsal colours have been broadly implicated in prey attraction. In a manipulative assay, I found that spiders actively control the orientation of their conspicuous banded signals in the web, with a distinct preference for near-diagonal bearings. Further field-based study identified a predictive relationship between pattern orientation and prey interception rates, with a local maximum at the spiders' preferred orientation. There were no morph-specific effects on capture success, either singularly or via an interaction with pattern orientation. These results reveal a dynamic element in a traditionally 'static' signalling context, and imply differential functions for chromatic and geometric signal components across visual contexts. More broadly, they underscore how multicomponent signal designs and display behaviours may coevolve to enhance efficacy in visual deception. © 2017 The Author(s).

  19. Epigeic spiders of the pastures of northern Wielkopolska

    Woźny, Marek

    2000-10-01

    Full Text Available The fauna of epigeic spiders (Araneae occurring on three different types of pastures in northern Wielkopolska was analysed. Studies were conducted from May 1992 to October 1993. The 18,995 specimens collected were classified as belonging to 137 species and 17 families. The family Linyphiidae proved the richest in species while Lycosidae was the most abundantly in terms of number of specimens. Zoocenological analysis of spider communities showed their differentiation testifying to differences in the sites studied. The dominants were: 1 Osowo Stare (Site 1: Pardosa palustris, 2 Sycyn Dolny (Site 2: Xerolycosa miniata, P. palustris, Xysticus kochi, 3 Braczewo (Site 3: Erigone dentipalpis, P. palustris. Seasonal changes of dominance of the species at each site were established. A comparison of changes of the species’ dominances in the years 1992 and 1993 disclosed similar values of the individual dominance coefficient at the sites in Osowo Stare and Braczewo. This result indicates the occurrence of the process of stabilization of these biocenoses and a tendency to equilibrium in the environment. The least stable proved to be the site at Sycyn Dolny. Analysis of the seasonal dynamics of epigeic spider communities was also made by determining the mean number of species at each site in the two years of study. The highest number of species was noted in spring. It is interesting to note the appearance of species which are rare or very rare in Poland such as: Lepthyphantes insignis, Ostearius melanopygius, Enoplognatha mordax and Enoplognatha oelandica.

  20. Architecture of SPIDER control and data acquisition system

    Luchetta, A.; Manduchi, G.; Taliercio, C.; Soppelsa, A.; Barbalace, A.; Paolucci, F.; Sartori, F.; Barbato, P.; Breda, M.; Capobianco, R.; Molon, F.; Moressa, M.; Polato, S.; Simionato, P.; Zampiva, E.

    2012-01-01

    The ITER Heating Neutral Beam injectors will be implemented in three steps: development of the ion source prototype, development of the full injector prototype, and, finally, construction of up to three ITER injectors. The first two steps will be carried out in the ITER neutral beam test facility under construction in Italy. The ion source prototype, referred to as SPIDER, which is currently in the development phase, is a complex experiment involving more than 20 plant units and operating with beam-on pulses lasting up to 1 h. As for control and data acquisition it requires fast and slow control (cycle time around 0.1 ms and 10 ms, respectively), synchronization (10 ns resolution), and data acquisition for about 1000 channels (analogue and images) with sampling frequencies up to tens of MS/s, data throughput up to 200 MB/s, and data storage volume of up to tens of TB/year. The paper describes the architecture of the SPIDER control and data acquisition system, discussing the SPIDER requirements and the ITER CODAC interfaces and specifications for plant system instrumentation and control.

  1. Seasonal variation of ground spiders in a Brazilian Savanna

    Marina Farcic Mineo

    2010-06-01

    Full Text Available The Brazilian Savanna Ecoregion (Cerrado is one of the richest biomes in the world, with a characteristic highly seasonal climate a dry season between May and September and a rainy season from October through April. Ground-dwelling spiders from three Cerrado phytophysiognomies, "campo cerrado", "cerrado" and "cerrad��o", were sampled using pitfall traps during two years, totaling 111 species and 3,529 individuals. The abundance of individuals and species richness was higher during the wet season. Fifty-eight species were captured exclusively during that period, whereas only nineteen were restricted to the dry season. Only two species were found in all samples. The number of juveniles was higher than the number of adults in all phytophysiognomies and in all species during both seasons. The highest abundance was registered in October and the lowest in April. Overall sex ratio was male-biased in all vegetation types sampled. Distinct climate variables affected the abundance of spiders depending on sex, age and vegetal physiognomy where they were sampled. This study involved the longest sampling of spider abundance and diversity on the ground of a Brazilian Savanna.

  2. Silkworms transformed with chimeric silkworm/spider silk genes spin composite silk fibers with improved mechanical properties

    The development of a spider silk manufacturing process is of great interest. piggyBac vectors were used to create transgenic silkworms encoding chimeric silkworm/spider silk proteins. The silk fibers produced by these animals were composite materials that included chimeric silkworm/spider silk prote...

  3. Optimization problem in quantum cryptography

    Brandt, Howard E

    2003-01-01

    A complete optimization was recently performed, yielding the maximum information gain by a general unitary entangling probe in the four-state protocol of quantum cryptography. A larger set of optimum probe parameters was found than was known previously from an incomplete optimization. In the present work, a detailed comparison is made between the complete and incomplete optimizations. Also, a new set of optimum probe parameters is identified for the four-state protocol

  4. Untangling spider silk evolution with spidroin terminal domains

    Garb Jessica E

    2010-08-01

    Full Text Available Abstract Background Spidroins are a unique family of large, structural proteins that make up the bulk of spider silk fibers. Due to the highly variable nature of their repetitive sequences, spidroin evolutionary relationships have principally been determined from their non-repetitive carboxy (C-terminal domains, though they offer limited character data. The few known spidroin amino (N-terminal domains have been difficult to obtain, but potentially contain critical phylogenetic information for reconstructing the diversification of spider silks. Here we used silk gland expression data (ESTs from highly divergent species to evaluate the functional significance and phylogenetic utility of spidroin N-terminal domains. Results We report 11 additional spidroin N-termini found by sequencing ~1,900 silk gland cDNAs from nine spider species that shared a common ancestor > 240 million years ago. In contrast to their hyper-variable repetitive regions, spidroin N-terminal domains have retained striking similarities in sequence identity, predicted secondary structure, and hydrophobicity. Through separate and combined phylogenetic analyses of N-terminal domains and their corresponding C-termini, we find that combined analysis produces the most resolved trees and that N-termini contribute more support and less conflict than the C-termini. These analyses show that paralogs largely group by silk gland type, except for the major ampullate spidroins. Moreover, spidroin structural motifs associated with superior tensile strength arose early in the history of this gene family, whereas a motif conferring greater extensibility convergently evolved in two distantly related paralogs. Conclusions A non-repetitive N-terminal domain appears to be a universal attribute of spidroin proteins, likely retained from the origin of spider silk production. Since this time, spidroin N-termini have maintained several features, consistent with this domain playing a key role in silk

  5. Vibration transmission through sheet webs of hobo spiders (Eratigena agrestis) and tangle webs of western black widow spiders (Latrodectus hesperus).

    Vibert, Samantha; Scott, Catherine; Gries, Gerhard

    2016-11-01

    Web-building spiders construct their own vibratory signaling environments. Web architecture should affect signal design, and vice versa, such that vibratory signals are transmitted with a minimum of attenuation and degradation. However, the web is the medium through which a spider senses both vibratory signals from courting males and cues produced by captured prey. Moreover, webs function not only in vibration transmission, but also in defense from predators and the elements. These multiple functions may impose conflicting selection pressures on web design. We investigated vibration transmission efficiency and accuracy through two web types with contrasting architectures: sheet webs of Eratigena agrestis (Agelenidae) and tangle webs of Latrodectus hesperus (Theridiidae). We measured vibration transmission efficiencies by playing frequency sweeps through webs with a piezoelectric vibrator and a loudspeaker, recording the resulting web vibrations at several locations on each web using a laser Doppler vibrometer. Transmission efficiencies through both web types were highly variable, with within-web variation greater than among-web variation. There was little difference in transmission efficiencies of longitudinal and transverse vibrations. The inconsistent transmission of specific frequencies through webs suggests that parameters other than frequency are most important in allowing these spiders to distinguish between vibrations of prey and courting males.

  6. The spider Harpactea sadistica: co-evolution of traumatic insemination and complex female genital morphology in spiders.

    Rezác, Milan

    2009-08-07

    The males of invertebrates from a few phyla, including arthropods, have been reported to practise traumatic insemination (TI; i.e. injecting sperm by using the copulatory organ to penetrate the female's body wall). As all previously reported arthropod examples have been insects, there is considerable interest in whether TI might have evolved independently in other arthropods. The research reported here demonstrates the first case of TI in the arthropod subphylum Chelicerata, in particular how the genital morphology and mating behaviour of Harpactea sadistica (Rezác 2008), a spider from Israel, has become adapted specifically for reproduction based on TI. Males have needle-like intromittent organs and females have atrophied spermathecae. In other spiders, eggs are fertilized simultaneously with oviposition, but the eggs of H. sadistica are fertilized in the ovaries (internal fertilization) and develop as embryos before being laid. Sperm-storage organs of phylogenetically basal groups to H. sadistica provide males with last male sperm priority and allow removal of sperm by males that mate later, suggesting that TI might have evolved as an adaptive strategy to circumvent an unfavourable structure of the sperm-storage organs, allowing the first male to mate with paternity advantage. Understanding the functional significance of TI gives us insight into factors underlying the evolution of the genital and sperm-storage morphology in spiders.

  7. Sperm dynamics in spiders (Araneae): ultrastructural analysis of the sperm activation process in the garden spider Argiope bruennichi (Scopoli, 1772).

    Vöcking, Oliver; Uhl, Gabriele; Michalik, Peter

    2013-01-01

    Storage of sperm inside the female genital tract is an integral phase of reproduction in many animal species. The sperm storage site constitutes the arena for sperm activation, sperm competition and female sperm choice. Consequently, to understand animal mating systems information on the processes that occur from sperm transfer to fertilization is required. Here, we focus on sperm activation in spiders. Male spiders produce sperm whose cell components are coiled within the sperm cell and that are surrounded by a proteinaceous sheath. These inactive and encapsulated sperm are transferred to the female spermathecae where they are stored for later fertilization. We analyzed the ultrastructural changes of sperm cells during residency time in the female genital system of the orb-web spider Argiope bruennichi. We found three clearly distinguishable sperm conditions: encapsulated sperm (secretion sheath present), decapsulated (secretion sheath absent) and uncoiled sperm (cell components uncoiled, presumably activated). After insemination, sperm remain in the encapsulated condition for several days and become decapsulated after variable periods of time. A variable portion of the decapsulated sperm transforms rapidly to the uncoiled condition resulting in a simultaneous occurrence of decapsulated and uncoiled sperm. After oviposition, only decapsulated and uncoiled sperm are left in the spermathecae, strongly suggesting that the activation process is not reversible. Furthermore, we found four different types of secretion in the spermathecae which might play a role in the decapsulation and activation process.

  8. The age and evolution of sociality in Stegodyphus spiders: a molecular phylogenetic perspective

    Johannesen, Jes; Lubin, Yael; Smith, Deborah R.

    2007-01-01

    suggested to be unstable in evolutionary time, and hence sociality a rare phenomenon in spiders. Based on a partial molecular phylogeny of the genus Stegodyphus, we address the hypothesis that social spiders in this genus are evolutionary transient. We estimate the age of the three social species, test...

  9. Contamination vs. harm-relevant outcome expectancies and covariation bias in spider phobia

    de Jong, Peter J.; Peters, Madelon L.

    There is increasing evidence that spiders are not feared because of harmful outcome expectancies but because of disgust and contamination-relevant outcome expectancies. This study investigated the relative strength of contamination- and harm-relevant UCS expectancies and covariation bias in spider

  10. Phylogenomics, Diversification Dynamics, and Comparative Transcriptomics across the Spider Tree of Life.

    Fernández, Rosa; Kallal, Robert J; Dimitrov, Dimitar; Ballesteros, Jesús A; Arnedo, Miquel A; Giribet, Gonzalo; Hormiga, Gustavo

    2018-05-07

    Dating back to almost 400 mya, spiders are among the most diverse terrestrial predators [1]. However, despite considerable effort [1-9], their phylogenetic relationships and diversification dynamics remain poorly understood. Here, we use a synergistic approach to study spider evolution through phylogenomics, comparative transcriptomics, and lineage diversification analyses. Our analyses, based on ca. 2,500 genes from 159 spider species, reject a single origin of the orb web (the "ancient orb-web hypothesis") and suggest that orb webs evolved multiple times since the late Triassic-Jurassic. We find no significant association between the loss of foraging webs and increases in diversification rates, suggesting that other factors (e.g., habitat heterogeneity or biotic interactions) potentially played a key role in spider diversification. Finally, we report notable genomic differences in the main spider lineages: while araneoids (ecribellate orb-weavers and their allies) reveal an enrichment in genes related to behavior and sensory reception, the retrolateral tibial apophysis (RTA) clade-the most diverse araneomorph spider lineage-shows enrichment in genes related to immune responses and polyphenic determination. This study, one of the largest invertebrate phylogenomic analyses to date, highlights the usefulness of transcriptomic data not only to build a robust backbone for the Spider Tree of Life, but also to address the genetic basis of diversification in the spider evolutionary chronicle. Copyright © 2018 Elsevier Ltd. All rights reserved.

  11. Neural correlation of successful cognitive behaviour therapy for spider phobia: a magnetoencephalography study.

    Wright, Barry; Alderson-Day, Ben; Prendergast, Garreth; Kennedy, Juliette; Bennett, Sophie; Docherty, Mary; Whitton, Clare; Manea, Laura; Gouws, Andre; Tomlinson, Heather; Green, Gary

    2013-12-30

    Cognitive behavioural therapy (CBT) can be an effective treatment for spider phobia, but the underlying neural correlates of therapeutic change are yet to be specified. The present study used magnetoencephalography (MEG) to study responses within the first half second, to phobogenic stimuli in a group of individuals with spider phobia prior to treatment (n=12) and then in nine of them following successful CBT (where they could touch and manage live large common house spiders) at least 9 months later. We also compared responses to a group of age-matched healthy control participants (n=11). Participants viewed static photographs of real spiders, other fear-inducing images (e.g. snakes, sharks) and neutral stimuli (e.g. kittens). Beamforming methods were used to localise sources of significant power changes in response to stimuli. Prior to treatment, participants with spider phobia showed a significant maximum response in the right frontal pole when viewing images of real spiders specifically. No significant frontal response was observed for either control participants or participants with spider phobia post-treatment. In addition, participants' subjective ratings of spider stimuli significantly predicted peak responses in right frontal regions. The implications for understanding brain-based effects of cognitive therapies are discussed. © 2013 Published by Elsevier Ireland Ltd.

  12. Biased interpretation and memory in children with varying levels of spider fear

    Klein, A.M.; Titulaer, G.; Simons, C.; Allart, E.; de Gier, E.; Bögels, S.M.; Becker, E.S.; Rinck, M.

    2014-01-01

    This study investigated multiple cognitive biases in children simultaneously, to investigate whether spider-fearful children display an interpretation bias, a recall bias, and source monitoring errors, and whether these biases are specific for spider-related materials. Furthermore, the independent

  13. Photoluminescent properties of spider silk coated with Eu-doped nanoceria

    Dmitrović, Svetlana, E-mail: svetlana8@vin.bg.ac.rs [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Nikolić, Marko G.; Jelenković, Branislav [University of Belgrade, Institute of Physics (Serbia); Prekajski, Marija [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia); Rabasović, Mihailo [University of Belgrade, Institute of Physics (Serbia); Zarubica, Aleksandra [University of Niš, Department of Chemistry, Faculty of Science and Mathematics (Serbia); Branković, Goran [University of Belgrade, Institute for Multidisciplinary Research, Department of Material Science (Serbia); Matović, Branko [University of Belgrade, Vinča Institute of Nuclear Sciences (Serbia)

    2017-02-15

    Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO{sub 3}){sub 3}) and ammonium hydroxide (NH{sub 4}OH). Depending on the relationship between Ce{sup 3+} ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

  14. In Vitro Evaluation of Spider Silk Meshes as a Potential Biomaterial for Bladder Reconstruction

    Steins, A.; Dik, P.; Müller, W.H.; Vervoort, S.J.; Reimers, K.; Kubhier, J.W.; Vogt, P.M.; van Apeldoorn, Aart A.; Coffer, P.J.; Schepers, K.

    2015-01-01

    Reconstruction of the bladder by means of both natural and synthetic materials remains a challenge due to severe adverse effects such as mechanical failure. Here we investigate the application of spider major ampullate gland-derived dragline silk from the Nephila edulis spider, a natural biomaterial

  15. Active optical sensor assessment of spider mite damage on greenhouse beans and cotton

    The two-spotted spider mite, Tetranychus urticae Koch is an important pest of cotton in mid-southern United States and causes yield reduction, and deprivation in fiber fitness. A greenhouse colony of the spider mite was used to infest cotton and pinto beans at the three-leaf and trifoliate stages, r...

  16. Utility Assessment Report for SPIDERS Phase 2: Ft. Carson (Rev 1.0)

    Barr, Jonathan L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Tuffner, Francis K. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hadley, Mark D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Schneider, Kevin P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2014-01-01

    This document contains the Utility Assessment Report (UAR) for the Phase 2 operational Demonstration (OD) of the Smart Power Infrastructure Demonstration for Energy Reliability and Security (SPIDERS) Joint Capability Technology Demonstration (JCTD). The UAR for Phase 2 shows that the SPIDERS system was able to meet the requirements of the Implementation Directive at Ft. Carson.

  17. High School Students' Attitudes Towards Spiders: A cross-cultural comparison

    Prokop, Pavol; Tolarovičová, Andrea; Camerik, Anne M.; Peterková, Viera

    2010-08-01

    Spiders are traditionally considered to be among the least popular of animals. Current evidence suggests that a negative attitude towards spiders could be influenced by both cultural and evolutionary pressures. Some researchers suggest that science education activities could positively influence students' perceptions of spiders. Their evidence is, however, ambivalent. Using a five-point score Likert-type questionnaire in which the items were developed in a similar way to four of Kellert's categories of attitude (scientistic, negativistic, naturalistic, and ecologistic) towards invertebrates, we compared the level of knowledge of and attitudes towards spiders of high school students from two countries, Slovakia (n = 354) and South Africa (n = 382). The students represented different cultures and followed dissimilar science education curricula. Only among the Slovakian students there was a statistically significant but low correlation between knowledge and attitude (r = 0.30). The South African students scored higher in the categories of scientistic, naturalistic, and ecologistic attitudes. Comparison of attitude towards spiders of indigenous Africans from coeducational Catholic schools revealed that South African students have greater fear of spiders than Slovakian students, supporting the biological preparedness hypothesis. This hypothesis predicts a greater fear of spiders in South Africa than in Europe since several South African spiders possess venoms that are dangerous to humans. The results of this study are discussed from science education, cultural, and evolutionary perspectives.

  18. Pupils' Views about Spiders. Learning in Science Project (Primary). Working Paper No. 123.

    Hawe, Eleanor

    The Learning in Science Project (Primary)--LISP(P)--investigated the ideas and interests about spiders held by 8- to 10-year-old children. Data included 303 questions--and answers to some of the questions--about spiders obtained from children in four classes and from responses obtained during individual interviews with 10 children from each age…

  19. Extended survival of spiders (Aranaeae) feeding on whitefly (Homoptera: Aleyrodidae) honeydew

    Honeydew produced by homopteran insects such as aphids, whiteflies and mealybugs, can be abundant in some crops and may represent an important food resource for spiders and other honeydew feeding natural enemies. Woolly whiteflies are common in south Texas citrus, and spiders consistently make up a...

  20. Methods of assembling and disassembling spider and burnable poison rod structures for nuclear reactors

    Walton, L.A.

    1981-01-01

    A method is described of joining burnable poison rods to the spider arms of a pressurised water power reactor fuel assembly which is proof against the reactor core environment but permits these rods to be removed from the spider simply, swiftly and delicately. (U.K.)

  1. A Web of Learning: Beyond "Itsy Bitsy Spider," Preschool Students Learn Science Content Naturally

    Evitt, Marie Faust

    2011-01-01

    One of the author's biggest challenges as a preschool teacher is helping children in a group see and touch and do. Hands-on explorations are important for everyone, but essential for young children. How can young children do hands-on explorations of spiders and their webs? Teachers do not want children handling all sorts of spiders. They worry…

  2. Species status and conservation issues of New Zealand's endemic Latrodectus spider species (Araneae: Theridiidae)

    Vink, Cor J; Sirvid, Phillip J; Malumbres-Olarte, Jagoba

    2008-01-01

    New Zealand has two endemic widow spiders, Latrodectus katipo Powell, 1871 and L. atritus Urquhart, 1890. Both species face many conservation threats and are actively managed. The species status of the Latrodectus spiders of New Zealand was assessed using molecular (COI, ITS1, ITS2...

  3. Postharvest fumigation of California table grapes with ozone to control Western black widow spider (Araneae: Theridiidae)

    Ozone fumigations were evaluated for postharvest control of Western black widow spider (BWS), Latrodectus hesperus (Chamberlin and Ivie), in fresh table grapes destined for export from California USA. Mature adult female black widow spiders were contained in separate gas-permeable cages within a flo...

  4. Spider foraging strategy affects trophic cascades under natural and drought conditions.

    Liu, Shengjie; Chen, Jin; Gan, Wenjin; Schaefer, Douglas; Gan, Jianmin; Yang, Xiaodong

    2015-07-23

    Spiders can cause trophic cascades affecting litter decomposition rates. However, it remains unclear how spiders with different foraging strategies influence faunal communities, or present cascading effects on decomposition. Furthermore, increased dry periods predicted in future climates will likely have important consequences for trophic interactions in detritus-based food webs. We investigated independent and interactive effects of spider predation and drought on litter decomposition in a tropical forest floor. We manipulated densities of dominant spiders with actively hunting or sit-and-wait foraging strategies in microcosms which mimicked the tropical-forest floor. We found a positive trophic cascade on litter decomposition was triggered by actively hunting spiders under ambient rainfall, but sit-and-wait spiders did not cause this. The drought treatment reversed the effect of actively hunting spiders on litter decomposition. Under drought conditions, we observed negative trophic cascade effects on litter decomposition in all three spider treatments. Thus, reduced rainfall can alter predator-induced indirect effects on lower trophic levels and ecosystem processes, and is an example of how such changes may alter trophic cascades in detritus-based webs of tropical forests.

  5. Photoluminescent properties of spider silk coated with Eu-doped nanoceria

    Dmitrović, Svetlana; Nikolić, Marko G.; Jelenković, Branislav; Prekajski, Marija; Rabasović, Mihailo; Zarubica, Aleksandra; Branković, Goran; Matović, Branko

    2017-01-01

    Spider dragline silk was coated with pure as well as Eu-doped ceria nanopowders at the room temperature. The treatment was done by immersion of the spider silk mesh into aqueous solutions of cerium nitrate (Ce(NO_3)_3) and ammonium hydroxide (NH_4OH). Depending on the relationship between Ce"3"+ ion and ammonium hydroxide concentration, coated fibers exhibited a different thickness. Obtained materials were studied by means of FESEM. It was found that ceria nanoparticles of average size of 3 nm were coated along spider thread. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) confirmed crystal nature of nanoparticle coating of spider silk. By using Williamson-Hall plots, crystallite size and strain were estimated. EDS measurement confirmed the presence of Eu in spider-Eu-doped ceria composite, and according to FTIR analysis, the interaction between CeO2 and spider silk was proposed. The morphology of obtained composite was observed by TEM. The photoluminescence emission spectra of spider silk coated with Eu-doped ceria were measured with two different excitations of 385 and 466 nm. The two-photon excited auto-fluorescence of spider silk coated with Eu-doped ceria was detected using a nonlinear laser scanning microscope. Obtained composite has a potential as a fluorescent labeling material in diverse applications.

  6. Spectral response of spider mite infested cotton: Mite density and miticide rate study

    Two-spotted spider mites are important pests in many agricultural systems. Spider mites (Acari: Tetranychidae) have been found to cause economic damage in corn, cotton, and sorghum. Adult glass vial bioassays indicate that Temprano™ (abamectin) is the most toxic technical miticide for adult two-spot...

  7. Differences among plant species in acceptance by the spider mite Tetranychus urticae Koch

    Boom, van den C.E.M.; Beek, van T.A.; Dicke, M.

    2003-01-01

    The spider mite Tetranychus urticae Koch has a broad range of host plants. However, the spider mite does not accept all plants to the same degree because of differences in nutritive and toxic constituents. Other factors, such as the induction of secondary metabolites, the morphology of a leaf

  8. Parasitization of a huntsman spider (Arachnida: Araneae: Sparassidae: Heteropoda venatoria by a mermithid nematode (Nematoda: Mermithidae

    Sachin P. Ranade

    2016-11-01

    Full Text Available The emergence of a mermithid worm from a huntsman spider Heteropoda venatoria was witnessed at Buxa Tiger Reserve, West Bengal.  It appears to be a first record of the spider family Sparassidae serving as a host for a member of the family Mermithidae. 

  9. The path to the nest of spiders The path to the nest of spiders

    Eliane Luz Bayer

    2008-04-01

    Full Text Available Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell. He tells us that this is a story in which iobody is a hero and nobody has the class consciousness necessary to unify them in the struggle. Calvino acknowledges that it was difficult to conciliate his experiences with the postwar literary movement which he calls Neo-expresSionism, a term which, he thinks, describes better Italian Neo-realism. This is a book with a full realistic depictior of the incongruousness of the whole situation, showing rumen beings driven by loneliness, aggressiveness, unfulfilment and failure to meet, their nerves frayed by the War. It reveals human beings in their weaknesses, subjected to deterministic fates changing roles according to circumstance. Partisans shift to the Nazi side and inform on their f rmer allies and vice-versa, being later chased in revenge. The novel has as its setting Italy under Fascism and unde German occupation, the Italian people being divided betw en the fascists of the "Black Brigade" and the "Partisa4s" who belonged to the Resistance. Although this is a pOlitical book, it has universal appeal. At the same time that it livens up historical facts about the period, it moves our feelings. Calvino's book is about World War II as it is viewed and felt by a small outcast, Pin, who makes considerable efforts to be accepted and understood by adults. In his daily life Pinsuffers the consequences Of the war. His aggressive disposition reflects the environment which he has been brought up in: since he was born, his country has been at war. Besides that, his only sister is a whore, whom he hates and despises. Italo Calvino writes in his preface to The Path to the Nest of Spiders that the novel answers to the "ripeness of the time" since ht wrote it after wartime, a period when everyone had a tale to tell

  10. Selective spider toxins reveal a role for Nav1.1 channel in mechanical pain

    Osteen, Jeremiah D.; Herzig, Volker; Gilchrist, John; Emrick, Joshua J.; Zhang, Chuchu; Wang, Xidao; Castro, Joel; Garcia-Caraballo, Sonia; Grundy, Luke; Rychkov, Grigori Y.; Weyer, Andy D.; Dekan, Zoltan; Undheim, Eivind A. B.; Alewood, Paul; Stucky, Cheryl L.; Brierley, Stuart M.; Basbaum, Allan I.; Bosmans, Frank; King, Glenn F.; Julius, David

    2016-01-01

    Voltage-gated sodium (Nav) channels initiate action potentials in most neurons, including primary afferent nerve fibers of the pain pathway. Local anesthetics block pain through non-specific actions at all Nav channels, but the discovery of selective modulators would facilitate the analysis of individual subtypes and their contributions to chemical, mechanical, or thermal pain. Here, we identify and characterize spider toxins that selectively activate the Nav1.1 subtype, whose role in nociception and pain has not been explored. We exploit these probes to demonstrate that Nav1.1-expressing fibers are modality-specific nociceptors: their activation elicits robust pain behaviors without neurogenic inflammation and produces profound hypersensitivity to mechanical, but not thermal, stimuli. In the gut, high-threshold mechanosensitive fibers also express Nav1.1 and show enhanced toxin sensitivity in a model of irritable bowel syndrome. Altogether, these findings establish an unexpected role for Nav1.1 in regulating the excitability of sensory nerve fibers that underlie mechanical pain. PMID:27281198

  11. Factors that influence the beta-diversity of spider communities in northwestern Argentinean Grasslands

    Sandra M. Rodriguez-Artigas

    2016-04-01

    Full Text Available Beta-diversity, defined as spatial replacement in species composition, is crucial to the understanding of how local communities assemble. These changes can be driven by environmental or geographic factors (such as geographic distance, or a combination of the two. Spiders have been shown to be good indicators of environmental quality. Accordingly, spiders are used in this work as model taxa to establish whether there is a decrease in community similarity that corresponds to geographic distance in the grasslands of the Campos & Malezales ecoregion (Corrientes. Furthermore, the influence of climactic factors and local vegetation heterogeneity (environmental factors on assemblage composition was evaluated. Finally, this study evaluated whether the differential dispersal capacity of spider families is a factor that influences their community structure at a regional scale. Spiders were collected with a G-Vac from vegetation in six grassland sites in the Campos & Malezales ecoregion that were separated by a minimum of 13 km. With this data, the impact of alpha-diversity and different environmental variables on the beta-diversity of spider communities was analysed. Likewise, the importance of species replacement and nesting on beta-diversity and their contribution to the regional diversity of spider families with different dispersion capacities was evaluated. The regional and site-specific inventories obtained were complete. The similarity between spider communities declined as the geographic distance between sites increased. Environmental variables also influenced community composition; stochastic events and abiotic forces were the principal intervening factors in assembly structure. The differential dispersal capacity of spider groups also influenced community structure at a regional scale. The regional beta-diversity, as well as species replacement, was greater in high and intermediate vagility spiders; while nesting was greater in spiders with low

  12. Association of spiders and lichen on Robben Island, South Africa: a case report

    A. Mukherjee

    2010-04-01

    Full Text Available The present study is a firstrecord of spider occurrence on Robben Island, South Africa. Some habitats were rich in lichens. As we know, lichens enhance wildlife habitat in less direct ways. The objective of the study was to examine the potential importance of lichens in enriching spider diversity and abundance. A total of 260 spiders (170 from lichens and 90 from bush were collected following the visual search method over one year. Seasonal trends in overall species richness and abundance indicated that the relative density of spiders was greater in lichens than in bushes. The result suggests that habitat structure, such as branch size and epiphytic lichen abundance, can be an explanation for the greater number of spiders in lichen-rich patches of the island.

  13. Intercropping With Fruit Trees Increases Population Abundance and Alters Species Composition of Spider Mites on Cotton.

    Li, Haiqiang; Pan, Hongsheng; Wang, Dongmei; Liu, Bing; Liu, Jian; Zhang, Jianping; Lu, Yanhui

    2018-05-05

    With the recent increase in planting of fruit trees in southern Xinjiang, the intercropping of fruit trees and cotton has been widely adopted. From 2014 to 2016, a large-scale study was conducted in Aksu, an important agricultural area in southern Xinjiang, to compare the abundance and species composition of spider mites in cotton fields under jujube-cotton, apple-cotton, and cotton monocrop systems. The abundance of spider mites in cotton fields under both intercropping systems was generally higher than in the cotton monocrop. The species composition of spider mites also differed greatly between cotton intercropped with apple or jujube compared to the cotton monocrop. The relative proportion of Tetranychus truncates Ehara (Acari: Tetranychidae) in the species complex generally increased while that of another spider mite, Tetranychus dunhuangensis Wang (Acari: Tetranychidae), decreased under fruit tree-cotton systems. More attention should be paid to the monitoring and management of spider mites, especially T. truncates in this important region of China.

  14. Distribution and importance of spiders inhabiting a Brazilian sugar cane plantation

    Isabela Maria Piovesan Rinaldi

    2002-07-01

    Full Text Available The spider fauna (Araneae of a sugar eane plantation was surveyed monthly by hand colteetion and beating vegetation in sugar cane fields across Botucatu, State of São Paulo, Brazil. Composition and rchness (family and species where identifieation to species was possible microhabitat preferenees were reeorded, and diversity and evenness indices were calculated. A total of 1291 spiders belonging to 73 species and 20 families were collected. The most diverse families were Theridiidae, Salticidae, and Araneidae, and the most abundant ones were Theridiidae, Saltieidae, Anyphaenidae, and Araneidae, Seven species represented 58.6% of the total fauna, with Crysso pulcherrima (Mello-Leitão,1917 (Theridiidae composing 28.2%. About 65% of the spiders occupied the upper part of the plants (above 20 cm. Five spider species were present in the sugar cane throughout crop development. Evidence of spiders feeding on sugar cane pest species was observed.

  15. The time course of location-avoidance learning in fear of spiders.

    Rinck, Mike; Koene, Marieke; Telli, Sibel; Moerman-van den Brink, Wiltine; Verhoeven, Barbara; Becker, Eni S

    2016-01-01

    Two experiments were designed to study the time course of avoidance learning in spider fearfuls (SFs) under controlled experimental conditions. To achieve this, we employed an immersive virtual environment (IVE): While walking freely through a virtual art museum to search for specific paintings, the participants were exposed to virtual spiders. Unbeknown to the participants, only two of four museum rooms contained spiders, allowing for avoidance learning. Indeed, the more SF the participants were, the faster they learned to avoid the rooms that contained spiders (Experiment. 1), and within the first six trials, high fearfuls already developed a preference for starting their search task in rooms without spiders (Experiment 2). These results illustrate the time course of avoidance learning in SFs, and they speak to the usefulness of IVEs in fundamental anxiety research.

  16. Spider genomes provide insight into composition and evolution of venom and silk

    Sanggaard, Kristian W.; Bechsgaard, Jesper S.; Fang, Xiaodong; Duan, Jinjie; Dyrlund, Thomas F.; Gupta, Vikas; Jiang, Xuanting; Cheng, Ling; Fan, Dingding; Feng, Yue; Han, Lijuan; Huang, Zhiyong; Wu, Zongze; Liao, Li; Settepani, Virginia; Thøgersen, Ida B.; Vanthournout, Bram; Wang, Tobias; Zhu, Yabing; Funch, Peter; Enghild, Jan J.; Schauser, Leif; Andersen, Stig U.; Villesen, Palle; Schierup, Mikkel H; Bilde, Trine; Wang, Jun

    2014-01-01

    Spiders are ecologically important predators with complex venom and extraordinarily tough silk that enables capture of large prey. Here we present the assembled genome of the social velvet spider and a draft assembly of the tarantula genome that represent two major taxonomic groups of spiders. The spider genomes are large with short exons and long introns, reminiscent of mammalian genomes. Phylogenetic analyses place spiders and ticks as sister groups supporting polyphyly of the Acari. Complex sets of venom and silk genes/proteins are identified. We find that venom genes evolved by sequential duplication, and that the toxic effect of venom is most likely activated by proteases present in the venom. The set of silk genes reveals a highly dynamic gene evolution, new types of silk genes and proteins, and a novel use of aciniform silk. These insights create new opportunities for pharmacological applications of venom and biomaterial applications of silk. PMID:24801114

  17. Community structure of spiders in coastal habitats of a Mediterranean delta region (Nestos Delta, NE Greece

    S. Buchholz

    2009-01-01

    Full Text Available (pp 101-115Habitat zonation and ecology of spider assemblages have been poorly studied in Mediterranean ecosystems. A first analysis of spider assemblages in coastal habitats in the east Mediterranean area is presented. The study area is the 250 km² Nestos Delta, located in East Macedonia in the North-East of Greece. Spiders were caught in pitfall traps at 17 sites from the beginning of April to the end of June 2004. Nonparametric estimators were used to determine species richness and alpha diversity. Ordination analysis (redundancy analysis indicated four clearly separable spider species groups (salt meadows, dunes, mea-dows and floodplain forests, along a soil salinity and moisture gradient. Based on these results we discuss the habitat preferences of these spiders and include the first ecological data on several species.

  18. Cognitive reappraisal of snake and spider pictures: An event-related potentials study.

    Langeslag, Sandra J E; van Strien, Jan W

    2018-05-30

    Fear of snakes and spiders are common animal phobias. Emotion regulation can change the response to emotional stimuli, including snakes and spiders. It is well known that emotion regulation modulates the late positive potential (LPP), which reflects sustained motivated attention. However, research concerning the effect of emotion regulation on the early posterior negativity (EPN), which reflects early selective attention, is scarce. The present research question was whether the EPN and LPP amplitudes are modulated by regulation of emotional responses to snake and spider stimuli. Emotion up- and down-regulation were expected to enhance and reduce the LPP amplitude, respectively, but emotion regulation was not expected to modulate the EPN amplitude. Female participants passively viewed snake, spider, and bird pictures, and up- and down-regulated their emotional responses to the snake and spider pictures using self-focused reappraisal, while their electroencephalogram was recorded. There were EPNs for snakes and spiders vs. birds, as well as for snakes vs. spiders. The LPP amplitude tended to be enhanced for snakes and spiders compared to birds. Most importantly, the LPP amplitude was larger in the up-regulate than in the down-regulate condition for both snakes and spiders, but there was no evidence that the EPN amplitude was modulated by emotion regulation. This suggests that emotion regulation modulated sustained motivated attention, but not early selective attention, to snakes and spiders. The findings are in line with the notion that the emotional modulation of the EPN is more automatic than the emotional modulation of the LPP. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. Beneficial Effects of Ants and Spiders on the Reproductive Value of Eriotheca gracilipes (Malvaceae) in a Tropical Savanna.

    Stefani, Vanessa; Pires, Tayna Lopes; Torezan-Silingardi, Helena Maura; Del-Claro, Kleber

    2015-01-01

    Predators affect plant fitness when they forage on them and reduce the action of herbivores. Our study evaluates the complementary effects of spiders and ants that visit the extrafloral nectaries of Eriotheca gracilipes (Malvaceae) on the production of fruits and viable seeds of these savanna trees. Four experimental groups were established: control group - with free access of spiders and ants; exclusion group - spiders and ants excluded; ant group - absence of spiders; and spider group - absence of ants. The presence of ants reduced the spider richness; however, the presence of spiders did not affect the ant richness. A significantly higher number of fruits per buds were found in the presence of spiders alone or spiders and ants together (control group) compared with the absence of both predators (exclusion group). The number of seeds per fruits and seed viability were higher in the control group. This is the first study showing that spiders and ants may exert a positive and complementary effect on the reproductive value of an extrafloral nectaried plant. Mostly the impact of ants and/or spiders on herbivores is considered, whereas our study reinforces the importance of evaluating the effect of multiple predators simultaneously, exploring how the interactions among predators with distinct skills may affect the herbivores and the plants on which they forage.

  20. From Midges to Spiders: Mercury Biotransport in Riparian Zones Near the Buffalo River Area of Concern (AOC), USA.

    Pennuto, C M; Smith, M

    2015-12-01

    Riparian communities can receive environmental contaminants from adjacent aquatic 'donor' habitats. We investigated mercury biotransport from aquatic to terrestrial habitats via aquatic insect emergence and uptake by riparian spiders at sites within and upstream of the Buffalo River Area of Concern (AOC), a site with known sediment Hg contamination. Mercury concentration in emerging midges was roughly 10× less than contaminated sediment levels with the AOC, but biomagnification factors from midges to spiders ranged from 2.0 to 2.65 between sites. There was a significantly negative body mass:total mercury relationship in spiders (p Spiders contained significantly more mercury than their midge prey and spiders upstream of the AOC had higher mercury concentrations than spiders from within the AOC. Collectively, these data indicate that riparian spiders can be good mercury sentinels in urban environments, and that riparian communities upstream from the AOC may be at greater risk to mercury than has been previously considered.

  1. Proximal Probes Facility

    Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

  2. Probe Techniques. Introductory Remarks

    Emeleus, K. G. [School of Physics and Applied Mathematics, Queen' s University, Belfast (United Kingdom)

    1968-04-15

    In this brief introduction to the session on probes, the history of theii development is first touched on briefly. Reference is then made to the significance of the work to be described by Medicus, for conductivity and recombination calculations, and by Lam and Su, for a wide range of medium and higher pressure plasmas. Finally, a number of other probe topics are mentioned, including multiple probes; probes in electronegative plasmas; resonance probes; probes in noisy discharges; probes as oscillation detectors; use of probes where space-charge is not negligible. (author)

  3. Spider monkey, Muriqui and Woolly monkey relationships revisited.

    de Lima, Margarida Maria Celeira; Sampaio, Iracilda; Vieira, Ricardo dos Santos; Schneider, Horacio

    2007-01-01

    The taxonomic relationships among the four genera of the Atelidae family, Alouatta (Howler), Ateles (Spider), Lagothrix (Woolly) and Brachyteles (Muriqui), have been the subject of great debate. In general, almost all authors agree with the assignment of Howler monkeys as the basal genus, either in its own tribe Alouattini or in the subfamily Alouattinae, but they disagree on the associations among the other members of the family. Muriquis have been grouped with Spider monkeys based on the fact that they share various behavioral and morphological characteristics. Cladistic analyses using morphological, biochemical, karyotype and behavioral characteristics depicted a phylogenetic tree that places Howler as the basal genus and the remaining genera in an unresolved politomy. More recent studies using molecular data have suggested that Muriqui and Woolly monkeys are sister groups. However, a recent study based on nuclear and mtDNA argued that politomy is what best represents the relationships among Spider, Woolly and Muriqui. To contribute to this debate we have added new data from two nuclear genes, Transferrin and von Willebrand Factor, and using an alignment of 17,997 bp we demonstrate that a total analysis strongly supports the Muriqui-Woolly clade. A gene-to-gene approach showed that four of the eight nuclear genes provide support for the Muriqui-Woolly clade, two strongly and two moderately, while none of the eight genes provide support for any alternative arrangement. The mitochondrial genes were not able to resolve the politomy. A possible reason for the difficulty in resolving atelid relationships may be the short period of time separating each cladogenetic event in the evolutionary process that shaped this family.

  4. SPIDERS (ARANEI IN HEPRETOBIONT MESOFAUNA OF THE NORTHWEST CAUCASUS

    A. V. Ponomarev

    2014-01-01

    Full Text Available Abstract. Aim. We discussed in previous work a herpetobiont fauna of arachnids (Arachnida from the isolated yewboxwood wood, located in the Caucasian State Biosphere Reserve, 20 km near Sochi (Ponomarev, Chumachenko, 2007. The aim of the paper is to summarize available data about herpetobiont araneofauna of the Northwest Caucasus. Location. Republic of Adygea, Russia.Methods. Material was collected in 2009 on north macroslope of Main Caucasian Ridge within the territory of the Caucasian State Biosphere Reserve between 1000–1820 m. The following plant communities are studied: beech-silver fir (assotiation Abieti-Fagetion orientalis Korotkov et Belonovskaya 1987, maple forest (assotiation Petasito albae-Abietetum nordmannianae subassotiation Aceretosum trautvetteri Francuzov 2006, subalpine meadow (assotiation Poa longifolii – Calamagrostietum arundinaceae Semagina, 1992. Soil traps were used for collection of spiders.Results and main conclusions. During the period of study 100 species of spiders from 19 families are registered. Most diverse araneofauna of subalpine meadows includs 54 species belonging to 14 families. The least diverse araneofauna is in maple forest (24 species of 7 families. In beech-silver fir includes 45 species of 16 families of spiders. Only 3 species (Pireneitega ovtchinnikovi, Cybaeus abchasicus, Tenuiphantes mengei were found in all surveyed habitats. These 3 species clearly tend to forest habitats. Herpetobiont araneofauna of the Northwest Caucasus characterized by high taxonomic diversity with clear predominance of representatives of the family Linyphiidae. Specificity of araneofauna in different types of plant communities is high.

  5. Variation in Protein Intake Induces Variation in Spider Silk Expression

    Blamires, Sean J.; Wu, Chun-Lin; Tso, I-Min

    2012-01-01

    Background It is energetically expensive to synthesize certain amino acids. The proteins (spidroins) of spider major ampullate (MA) silk, MaSp1 and MaSp2, differ in amino acid composition. Glutamine and proline are prevalent in MaSp2 and are expensive to synthesize. Since most orb web spiders express high proline silk they might preferentially attain the amino acids needed for silk from food and shift toward expressing more MaSp1 in their MA silk when starved. Methodology/Principal Findings We fed three spiders; Argiope aetherea, Cyrtophora moluccensis and Leucauge blanda, high protein, low protein or no protein solutions. A. aetherea and L. blanda MA silks are high in proline, while C. moluccesnsis MA silks are low in proline. After 10 days of feeding we determined the amino acid compositions and mechanical properties of each species' MA silk and compared them between species and treatments with pre-treatment samples, accounting for ancestry. We found that the proline and glutamine of A. aetherea and L. blanda silks were affected by protein intake; significantly decreasing under the low and no protein intake treatments. Glutmaine composition in C. moluccensis silk was likewise affected by protein intake. However, the composition of proline in their MA silk was not significantly affected by protein intake. Conclusions Our results suggest that protein limitation induces a shift toward different silk proteins with lower glutamine and/or proline content. Contradictions to the MaSp model lie in the findings that C. moluccensis MA silks did not experience a significant reduction in proline and A. aetherea did not experience a significant reduction in serine on low/no protein. The mechanical properties of the silks could not be explained by a MaSp1 expressional shift. Factors other than MaSp expression, such as the expression of spidroin-like orthologues, may impact on silk amino acid composition and spinning and glandular processes may impact mechanics. PMID:22363691

  6. Gamma-ray imaging probes

    Wild, W.J.

    1988-01-01

    External nuclear medicine diagnostic imaging of early primary and metastatic lung cancer tumors is difficult due to the poor sensitivity and resolution of existing gamma cameras. Nonimaging counting detectors used for internal tumor detection give ambiguous results because distant background variations are difficult to discriminate from neighboring tumor sites. This suggests that an internal imaging nuclear medicine probe, particularly an esophageal probe, may be advantageously used to detect small tumors because of the ability to discriminate against background variations and the capability to get close to sites neighboring the esophagus. The design, theory of operation, preliminary bench tests, characterization of noise behavior and optimization of such an imaging probe is the central theme of this work

  7. The Linking Probability of Deep Spider-Web Networks

    Pippenger, Nicholas

    2005-01-01

    We consider crossbar switching networks with base $b$ (that is, constructed from $b\\times b$ crossbar switches), scale $k$ (that is, with $b^k$ inputs, $b^k$ outputs and $b^k$ links between each consecutive pair of stages) and depth $l$ (that is, with $l$ stages). We assume that the crossbars are interconnected according to the spider-web pattern, whereby two diverging paths reconverge only after at least $k$ stages. We assume that each vertex is independently idle with probability $q$, the v...

  8. Aggression and conflict management at fusion in spider monkeys.

    Aureli, Filippo; Schaffner, Colleen M

    2007-04-22

    In social systems characterized by a high degree of fission-fusion dynamics, members of a large community are rarely all together, spending most of their time in smaller subgroups with flexible membership. Although fissioning into smaller subgroups is believed to reduce conflict among community members, fusions may create conflict among individuals from joining subgroups. Here, we present evidence for aggressive escalation at fusion and its mitigation by the use of embraces in wild spider monkeys (Ateles geoffroyi). Our findings provide the first systematic evidence for conflict management at fusion and may have implications for the function of human greetings.

  9. Structure determination of spider silk from X-ray images

    Ulrich, Stephan; Zippelius, Annette [Universitaet Goettingen, Institut fuer Theoretische Physik (Germany); Meling, Martin [Max-Planck-Institut fuer biophysikalische Chemie, Goettingen (Germany); Glisovic, Anja; Salditt, Tim [Universitaet Goettingen, Institut fuer Roentgenphysik (Germany)

    2008-07-01

    Spider silk consists of interconnected crystallites, which are typically aligned along the fiber axis. We present a method to systematically determine the structure of these crystallites. Hereby we introduce a model that calculates the scattering function G(q) which is fitted to the measured X-ray image (silk from nephila clavipes). With it, the crystallites' size, the constitution and dimensions of their unit cell, as well as their tilt with respect to the fiber axis is identified, and furthermore the effect of coherent scattering from different crystallites is investigated. The shown methods and the presented model can easily be generalized to a wide class of composite materials.

  10. Ineffective crypsis in a crab spider: a prey community perspective

    Brechbühl, Rolf; Casas, Jérôme; Bacher, Sven

    2009-01-01

    Cryptic coloration is assumed to be beneficial to predators because of an increased encounter rate with unwary prey. This hypothesis is, however, very rarely, if ever, studied in the field. The aim of this study was to quantify the encounter rate and capture success of an ambush predator, in the field, as a function of its level of colour-matching with the background. We used the crab spider Misumena vatia, which varies its body colour and can thereby match the colour of the flower it hunts u...

  11. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest.

    Yann Hénaut

    Full Text Available Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between 'Aechmea-areas' and 'control-areas' of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests.

  12. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest.

    Hénaut, Yann; Corbara, Bruno; Pélozuelo, Laurent; Azémar, Frédéric; Céréghino, Régis; Herault, Bruno; Dejean, Alain

    2014-01-01

    Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between 'Aechmea-areas' and 'control-areas' of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests.

  13. Environmental and hormonal factors controlling reversible colour change in crab spiders.

    Llandres, Ana L; Figon, Florent; Christidès, Jean-Philippe; Mandon, Nicole; Casas, Jérôme

    2013-10-15

    Habitat heterogeneity that occurs within an individual's lifetime may favour the evolution of reversible plasticity. Colour reversibility has many different functions in animals, such as thermoregulation, crypsis through background matching and social interactions. However, the mechanisms underlying reversible colour changes are yet to be thoroughly investigated. This study aims to determine the environmental and hormonal factors underlying morphological colour changes in Thomisus onustus crab spiders and the biochemical metabolites produced during these changes. We quantified the dynamics of colour changes over time: spiders were kept in yellow and white containers under natural light conditions and their colour was measured over 15 days using a spectrophotometer. We also characterised the chemical metabolites of spiders changing to a yellow colour using HPLC. Hormonal control of colour change was investigated by injecting 20-hydroxyecdysone (20E) into spiders. We found that background colouration was a major environmental factor responsible for colour change in crab spiders: individuals presented with white and yellow backgrounds changed to white and yellow colours, respectively. An ommochrome precursor, 3-OH-kynurenine, was the main pigment responsible for yellow colour. Spiders injected with 20E displayed a similar rate of change towards yellow colouration as spiders kept in yellow containers and exposed to natural sunlight. This study demonstrates novel hormonal manipulations that are capable of inducing reversible colour change.

  14. Comparative growth and development of spiders reared on live and dead prey.

    Peng, Yu; Zhang, Fan; Gui, Shaolan; Qiao, Huping; Hose, Grant C

    2013-01-01

    Scavenging (feeding on dead prey) has been demonstrated across a number of spider families, yet the implications of feeding on dead prey for the growth and development of individuals and population is unknown. In this study we compare the growth, development, and predatory activity of two species of spiders that were fed on live and dead prey. Pardosa astrigera (Lycosidae) and Hylyphantes graminicola (Lyniphiidae) were fed live or dead fruit flies, Drosophila melanogaster. The survival of P. astrigera and H. graminicola was not affected by prey type. The duration of late instars of P. astrigera fed dead prey were longer and mature spiders had less protein content than those fed live prey, whereas there were no differences in the rate of H. graminicola development, but the mass of mature spiders fed dead prey was greater than those fed live prey. Predation rates by P. astrigera did not differ between the two prey types, but H. graminicola had a higher rate of predation on dead than alive prey, presumably because the dead flies were easier to catch and handle. Overall, the growth, development and reproduction of H. graminicola reared with dead flies was better than those reared on live flies, yet for the larger P. astrigera, dead prey may suit smaller instars but mature spiders may be best maintained with live prey. We have clearly demonstrated that dead prey may be suitable for rearing spiders, although the success of the spiders fed such prey appears size- and species specific.

  15. A Tank Bromeliad Favors Spider Presence in a Neotropical Inundated Forest

    Hénaut, Yann; Corbara, Bruno; Pélozuelo, Laurent; Azémar, Frédéric; Céréghino, Régis; Herault, Bruno; Dejean, Alain

    2014-01-01

    Tank bromeliads are good models for understanding how climate change may affect biotic associations. We studied the relationships between spiders, the epiphytic tank bromeliad, Aechmea bracteata, and its associated ants in an inundated forest in Quintana Roo, Mexico, during a drought period while, exceptionally, this forest was dry and then during the flooding that followed. We compared spider abundance and diversity between ‘Aechmea-areas’ and ‘control-areas’ of the same surface area. We recorded six spider families: the Dipluridae, Ctenidae, Salticidae, Araneidae, Tetragnathidae and Linyphiidae among which the funnel-web tarantula, Ischnothele caudata, the only Dipluridae noted, was the most abundant. During the drought period, the spiders were more numerous in the Aechmea-areas than in the control-areas, but they were not obligatorily associated with the Aechmea. During the subsequent flooding, the spiders were concentrated in the A. bracteata patches, particularly those sheltering an ant colony. Also, a kind of specificity existed between certain spider taxa and ant species, but varied between the drought period and subsequent flooding. We conclude that climatic events modulate the relationship between A. bracteata patches and their associated fauna. Tank bromeliads, previously considered only for their ecological importance in supplying food and water during drought, may also be considered refuges for spiders during flooding. More generally, tank bromeliads have an important role in preserving non-specialized fauna in inundated forests. PMID:25494055

  16. Effects of kaolin particle films on the life span of an orb-weaver spider.

    Benhadi-Marín, Jacinto; Pereira, José Alberto; Santos, Sónia A P

    2016-02-01

    Araniella cucurbitina (Araneae: Araneidae) is a widespread orb-weaver spider commonly found in agroecosystems. Mineral particle films such as kaolin, due to their protective or anti-feeding action, can represent an alternative to pesticides, especially in organic farming systems, but little is known about its effects on A. cucurbitina. Therefore, we tested the effect of kaolin sprays on the life span of A. cucurbitina under laboratory conditions. Four treatments were tested encompassing different exposure routes. Thus, kaolin sprays were applied on (i) the surface, (ii) the prey (fly), (iii) the spider and (iv) both spider & prey. A control group was tested with water in each treatment. Results showed that sprays of kaolin significantly affected the survival of A. curcubitina when applications were done on the surface and on both spider & prey registering a reduction of 48% and 56%, respectively. Spiders in control obtained higher probability of reaching alive at the end of the assay than those treated with kaolin. Differences observed can be explained by the feeding behavior of the species and may depend on the consumption of the web by the spider and the ratio spider/fly for body size. Copyright © 2015 Elsevier Ltd. All rights reserved.

  17. Interpretative bias in spider phobia: Perception and information processing of ambiguous schematic stimuli.

    Haberkamp, Anke; Schmidt, Filipp

    2015-09-01

    This study investigates the interpretative bias in spider phobia with respect to rapid visuomotor processing. We compared perception, evaluation, and visuomotor processing of ambiguous schematic stimuli between spider-fearful and control participants. Stimuli were produced by gradually morphing schematic flowers into spiders. Participants rated these stimuli related to their perceptual appearance and to their feelings of valence, disgust, and arousal. Also, they responded to the same stimuli within a response priming paradigm that measures rapid motor activation. Spider-fearful individuals showed an interpretative bias (i.e., ambiguous stimuli were perceived as more similar to spiders) and rated spider-like stimuli as more unpleasant, disgusting, and arousing. However, we observed no differences between spider-fearful and control participants in priming effects for ambiguous stimuli. For non-ambiguous stimuli, we observed a similar enhancement for phobic pictures as has been reported previously for natural images. We discuss our findings with respect to the visual representation of morphed stimuli and to perceptual learning processes. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Deer herbivory reduces web-building spider abundance by simplifying forest vegetation structure

    Elizabeth J. Roberson

    2016-09-01

    Full Text Available Indirect ecological effects are a common feature of ecological systems, arising when one species affects interactions among two or more other species. We examined how browsing by white-tailed deer (Odocoileus virginianus indirectly affected the abundance and composition of a web-building spider guild through their effects on the structure of the ground and shrub layers of northern hardwood forests. We examined paired plots consisting of deer-free and control plots in the Allegheny Plateau region Pennsylvania and Northern Highlands region of Wisconsin. We recorded the abundance of seven types of webs, each corresponding to a family of web-building spiders. We quantified vegetation structure and habitat suitability for the spiders by computing a web scaffold availability index (WSAI at 0.5 m and 1.0 m above the ground. At Northern Highlands sites, we recorded prey availability. Spider webs were twice as abundant in deer-free plots compared to control plots, while WSAI was 7–12 times greater in deerfree plots. Prey availability was lower in deer-free plots. With the exception of funnel web-builders, all spider web types were significantly more abundant in deer-free plots. Both deer exclusion and the geographic region of plots were significant predictors of spider community structure. In closed canopy forests with high browsing pressure, the low density of tree saplings and shrubs provides few locations for web-building spiders to anchor webs. Recruitment of these spiders may become coupled with forest disturbance events that increase tree and shrub recruitment. By modifying habitat structure, deer appear to indirectly modify arthropod food web interactions. As deer populations have increased in eastern North America over the past several decades, the effects of deer on web-building spiders may be widespread.

  19. Influence of Imidacloprid and Horticultural Oil on Spider Abundance on Eastern Hemlock in the Southern Appalachians.

    Hakeem, A; Grant, J F; Lambdin, P L; Hale, F A; Rhea, J R; Wiggins, G J; Coots, C

    2018-05-08

    Hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae), is an exotic pest of eastern hemlock, Tsuga canadensis (L.) Carrière (Pinales: Pinaceae), in the eastern United States. Two commonly used insecticides to manage adelgid are imidacloprid, a systemic neonicotinoid insecticide, and horticultural oil, a refined petroleum oil foliar spray. We have investigated the influence of imidacloprid and horticultural oil on spider abundance at different canopy strata in eastern hemlock. In total, 2,084 spiders representing 11 families were collected from the canopies of eastern hemlock. In beat-sheet and direct observation samples, the families Theridiidae, Araneidae, Salticidae, and Anyphaenidae were the most abundant. Significantly higher numbers of spiders were recorded on untreated control trees compared with trees treated with imidacloprid using soil drench and soil injection applications. Spider abundance in trees injected with imidacloprid and horticultural oil applications did not significantly differ from control trees. Spider abundance was significantly greater in the top and middle strata of the canopy than in the bottom stratum, where imidacloprid concentrations were the highest. Regression analysis showed that spider abundance was inversely associated with imidacloprid concentration. This research demonstrates that imidacloprid, when applied with selected methods, has the potential to result in reductions of spider densities at different strata. However, slight reductions in spider abundance may be an acceptable short-term ecological impact compared with the loss of an untreated hemlock and all the associated ecological benefits that it provides. Future studies should include investigations of long-term impact of imidacloprid on spiders associated with eastern hemlock.

  20. Eddy-current probe design

    Kincaid, T.G.; McCary, R.O.

    1983-01-01

    This paper describes theoretical and experimental work directed toward finding the optimum probe dimensions and operating frequency for eddy current detection of half-penny surface cracks in nonmagnetic conducting materials. The study applies to probes which excite an approximately uniform spatial field over the length of the crack at the surface of the material. In practical terms, this means that the probe is not smaller than the crack length in any of its critical dimensions. The optimization of a simple coil probe is first analyzed in detail. It is shown that signal-to-noise ratio and lift-off discrimination are maximized by a pancake coil with mean radius not greater than the crack length, operated at a frequency which gives a skin depth equal to the crack depth. The results obtained for the simple coil are then used as a basis for discussion of the design of coils with ferrite cores and shields, and for the design of recording head type probes

  1. Subsocial behaviour and brood adoption in mixed-species colonies of two theridiid spiders

    Grinsted, Lena; Agnarsson, Ingi; Bilde, Trine

    2012-01-01

    , aggression and cooperation through behavioural experiments and examine the potential for adoption of foreign brood. Morphological and genetic analyses confirmed that colonies consisted of two related species Chikunia nigra (O.P. Cambridge, 1880) new combination (previously Chrysso nigra) and a yet...... as in territorial, colonial spiders. Mixed species spider colonies, involving closely related species, have rarely been documented. We examined social interactions in newly discovered mixed-species colonies of theridiid spiders on Bali, Indonesia. Our aim was to test the degree of intra- and interspecific tolerance...

  2. Compositional changes in spider (Araneae) assemblages along an urbanisation gradient near a Danish town

    Horváth, R.; Elek, Zoltán; Lövei, Gabor L

    2014-01-01

    Spider (Araneae) assemblages were studied over two years by pitfall trapping along an urbanisation gradient of forested habitats (rural forest - suburban forest fragment - urban forest fragment) in a Danish town, using the Globenet protocol. During the two years, we collected 4340 individuals of 90...... species, with money spiders (Linyphiidae) and wolf spiders (Lycosidae) being most numerous. One species, Ero aphana, was new to the Danish fauna. In 2004, 45-47 species were captured in the habitats in various stages of urbanisation, while in 2005 (with a smaller collection effort), 28 (urban) - 37 (rural...

  3. Study of probe-sample distance for biomedical spectra measurement

    Li Lei

    2011-11-01

    Full Text Available Abstract Background Fiber-based optical spectroscopy has been widely used for biomedical applications. However, the effect of probe-sample distance on the collection efficiency has not been well investigated. Method In this paper, we presented a theoretical model to maximize the illumination and collection efficiency in designing fiber optic probes for biomedical spectra measurement. This model was in general applicable to probes with single or multiple fibers at an arbitrary incident angle. In order to demonstrate the theory, a fluorescence spectrometer was used to measure the fluorescence of human finger skin at various probe-sample distances. The fluorescence spectrum and the total fluorescence intensity were recorded. Results The theoretical results show that for single fiber probes, contact measurement always provides the best results. While for multi-fiber probes, there is an optimal probe distance. When a 400- μm excitation fiber is used to deliver the light to the skin and another six 400- μm fibers surrounding the excitation fiber are used to collect the fluorescence signal, the experimental results show that human finger skin has very strong fluorescence between 475 nm and 700 nm under 450 nm excitation. The fluorescence intensity is heavily dependent on the probe-sample distance and there is an optimal probe distance. Conclusions We investigated a number of probe-sample configurations and found that contact measurement could be the primary choice for single-fiber probes, but was very inefficient for multi-fiber probes. There was an optimal probe-sample distance for multi-fiber probes. By carefully choosing the probe-sample distance, the collection efficiency could be enhanced by 5-10 times. Our experiments demonstrated that the experimental results of the probe-sample distance dependence of collection efficiency in multi-fiber probes were in general agreement with our theory.

  4. Compliant threads maximize spider silk connection strength and toughness

    Meyer, Avery; Pugno, Nicola M.; Cranford, Steven W.

    2014-01-01

    Millions of years of evolution have adapted spider webs to achieve a range of functionalities, including the well-known capture of prey, with efficient use of material. One feature that has escaped extensive investigation is the silk-on-silk connection joints within spider webs, particularly from a structural mechanics perspective. We report a joint theoretical and computational analysis of an idealized silk-on-silk fibre junction. By modifying the theory of multiple peeling, we quantitatively compare the performance of the system while systematically increasing the rigidity of the anchor thread, by both scaling the stress–strain response and the introduction of an applied pre-strain. The results of our study indicate that compliance is a virtue—the more extensible the anchorage, the tougher and stronger the connection becomes. In consideration of the theoretical model, in comparison with rigid substrates, a compliant anchorage enormously increases the effective adhesion strength (work required to detach), independent of the adhered thread itself, attributed to a nonlinear alignment between thread and anchor (contact peeling angle). The results can direct novel engineering design principles to achieve possible load transfer from compliant fibre-to-fibre anchorages, be they silk-on-silk or another, as-yet undeveloped, system. PMID:25008083

  5. Nectar Meals of a Mosquito-Specialist Spider

    Josiah O. Kuja

    2012-01-01

    Full Text Available Evarcha culicivora, an East African jumping spider, is known for feeding indirectly on vertebrate blood by actively choosing blood-carrying mosquitoes as prey. Using cold-anthrone tests to detect fructose, we demonstrate that E. culicivora also feeds on nectar. Field-collected individuals, found on the plant Lantana camara, tested positive for plant sugar (fructose. In the laboratory, E. culicivora tested positive for fructose after being kept with L. camara or one of another ten plant species (Aloe vera, Clerodendron magnifica, Hamelia patens, Lantana montevideo, Leonotis nepetaefolia, Parthenium hysterophorus, Ricinus communis, Senna didymobotrya, Striga asiatica, and Verbena trivernia. Our findings demonstrate that E. culicivora acquires fructose from its natural diet and can ingest fructose directly from plant nectaries. However, experiments in the laboratory also show that E. culicivora can obtain fructose indirectly by feeding on prey that have fed on fructose, implying a need to consider this possibility when field-collected spiders test positive for fructose. In laboratory tests, 53.5% of 1,215 small juveniles, but only 3.4% of 622 adult E. culicivora, left with plants for 24 hours, were positive for fructose. These findings, along with the field data, suggest that fructose is especially important for early-instar juveniles of E. culicivora.

  6. Tetracycline Reduces Kidney Damage Induced by Loxosceles Spider Venom

    Cinthya Kimori Okamoto

    2017-03-01

    Full Text Available Envenomation by Loxosceles spider can result in two clinical manifestations: cutaneous and systemic loxoscelism, the latter of which includes renal failure. Although incidence of renal failure is low, it is the main cause of death, occurring mainly in children. The sphingomyelinase D (SMase D is the main component in Loxosceles spider venom responsible for local and systemic manifestations. This study aimed to investigate the toxicity of L. intermedia venom and SMase D on kidney cells, using both In vitro and in vivo models, and the possible involvement of endogenous metalloproteinases (MMP. Results demonstrated that venom and SMase D are able to cause death of human kidney cells by apoptosis, concomitant with activation and secretion of extracellular matrix metalloproteases, MMP-2 and MMP-9. Furthermore, cell death and MMP synthesis and secretion can be prevented by tetracycline. In a mouse model of systemic loxoscelism, Loxosceles venom-induced kidney failure was observed, which was abrogated by administration of tetracycline. These results indicate that MMPs may play an important role in Loxosceles venom-induced kidney injury and that tetracycline administration may be useful in the treatment of human systemic loxoscelism.

  7. An insecticidal toxin from Nephila clavata spider venom.

    Jin, Lin; Fang, Mingqian; Chen, Mengrou; Zhou, Chunling; Ombati, Rose; Hakim, Md Abdul; Mo, Guoxiang; Lai, Ren; Yan, Xiuwen; Wang, Yumin; Yang, Shilong

    2017-07-01

    Spiders are the most successful insect predators given that they use their venom containing insecticidal peptides as biochemical weapons for preying. Due to the high specificity and potency of peptidic toxins, discoveries of insecticidal toxins from spider venom have provided an opportunity to obtain natural compounds for agricultural applications without affecting human health. In this study, a novel insecticidal toxin (μ-NPTX-Nc1a) was identified and characterized from the venom of Nephila clavata. Its primary sequence is GCNPDCTGIQCGWPRCPGGQNPVMDKCVSCCPFCPPKSAQG which was determined by automated Edman degradation, cDNA cloning, and MS/MS analysis. BLAST search indicated that Nc1a shows no similarity with known peptides or proteins, indicating that Nc1a belongs to a novel family of insecticidal peptide. Nc1a displayed inhibitory effects on Na V and K V channels in cockroach dorsal unpaired median neurons. The median lethal dose (LD50) of Nc1a on cockroach was 573 ng/g. Herein, a study that identifies a novel insecticidal toxin, which can be a potential candidate and/or template for the development of bioinsecticides, is presented.

  8. Tests for attraction to prey and predator avoidance by chemical cues in spiders of the beech forest floor

    Wetter, Melissa B.

    2012-07-01

    Full Text Available Spiders leave draglines, faeces and other secretions behind when traveling through their microhabitat. The presence of these secretions may unintentionally inform other animals, prey as well as predators, about a recent and possible current predation risk or food availability. For a wolf spider, other spiders including smaller conspecifics, form a substantial part of their prey, and larger wolf spiders, again including conspecifics, are potential predators. We tested two hypotheses: that large wolf spiders may locate patches of potential spider prey through the presence of silk threads and/or other secretions; and that prey spiders may use secretions from large wolf spiders to avoid patches with high predation risk. We used large (subadult or adult Pardosa saltans to provide predator cues and mixed dwarf spiders or small (juvenile P. saltans to provide prey cues. Subadult wolf spiders were significantly attracted to litter contaminated by dwarf spiders or small conspecifics after 6 hours but no longer after 24 hours. In contrast, neither dwarf spiders nor small P. saltans showed significant avoidance of substrate contaminated by adult P. saltans. However, small P. saltans showed different activity patterns on the two substrates. The results indicate that wolf spiders are able to increase the efficiency of foraging by searching preferentially in patches with the presence of intraguild prey. The lack of a clear patch selection response of the prey in spite of a modified activity pattern may possibly be associated with the vertical stratification of the beech litter habitat: the reduced volume of spaces in the deeper layers could make downward rather than horizontal movement a fast and safe tactic against a large predator that cannot enter these spaces.

  9. Active optical sensor assessment of spider mite damage on greenhouse beans and cotton.

    Martin, Daniel E; Latheef, Mohamed A

    2018-02-01

    The two-spotted spider mite, Tetranychus urticae Koch, is an important pest of cotton in mid-southern USA and causes yield reduction and deprivation in fiber fitness. Cotton and pinto beans grown in the greenhouse were infested with spider mites at the three-leaf and trifoliate stages, respectively. Spider mite damage on cotton and bean canopies expressed as normalized difference vegetation index indicative of changes in plant health was measured for 27 consecutive days. Plant health decreased incrementally for cotton until day 21 when complete destruction occurred. Thereafter, regrowth reversed decline in plant health. On spider mite treated beans, plant vigor plateaued until day 11 when plant health declined incrementally. Results indicate that pinto beans were better suited as a host plant than cotton for rearing T. urticae in the laboratory.

  10. Mediterranean Recluse Spider, Loxosceles rufescens (Araneae: Sicariidae from Charkhab Cave, Southern Iran

    Saber Sadeghi

    2017-04-01

    Full Text Available Background: The best-known dangerous spiders belong to the six genera. The genus Loxosceles or violin spiders are well known for their ability to cause skin necrosis or loxoscelism. All Loxosceles species have medical im­portance due to their necrotizing venom. The present article reports the occurrence of L. rufescens in Charkhab Cave, south of Iran (Larestan.Methods: The specimens were collected from the Charkhab Cave using handling forceps, paintbrush and aspirator and preserved in 96% ethanol.Results: Loxosceles rufescens, a medically important spider, is recorded from Charkhab Cave in Fars Province (southwest of Iran. Identification of L. rufescens was performed based on external morphology and the features of male genitalia.Conclusion: Presence of L. rufescens in south of Iran especially in a cave confirmed that this species is a widely distributed species in Iran. Therefore, cavers or cave visitors should be aware of this poisonous spider in caves.

  11. Contamination and Harm Relevant UCS-Expectancy Bias in Spider Phobic Individuals : Influence of Treatment

    van Overveld, Mark; de Jong, Peter J.; Huijding, Jorg; Peters, Madelon L.

    2010-01-01

    Phobic individuals expect aversive UCS's following encounters with phobic stimuli. Previous research using a thought-experiment procedure showed that contamination rather than harm-related outcome expectancies differentiated best between high and low spider fearful undergraduates. This study

  12. The distribution of spiders and Harvestmen (Chelicerata) in the Dutch National Park "De Hoge Veluwe"

    Hammen, van der L.

    1983-01-01

    A preliminary study is made of the distribution of Araneida and Opilionida (Chelicerata) in a National Park in The Netherlands. Special attention is paid to the influence of vegetation structure on the distribution of the spiders.

  13. Envia garciai, a new genus and species of mygalomorph spiders (Araneae, Microstigmatidae from Brazilian Amazonia

    Ott Ricardo

    2003-01-01

    Full Text Available The genus Envia, comprising only the new species Envia garciai, is proposed. These small mygalomorph spiders were abundantly collected in soil cores and litter samples in primary rain forests near Manaus, Amazonas, Brazil.

  14. Studies on the occurrence of true spiders as natural enemies in many Egyptian fields

    Amira A. Ibrahim

    2012-01-01

    Full Text Available True spiders represent one of the most important natural predatory species in Egyptian fields. In this work, common true spiders were surveyed in wheat, cotton and maize fields, and were counted weekly by using the direct method. For evaluating the feeding consumption of true spiders, five feeding cases were tested (as preys. These cases were: eggs of Ephestia kuehniella, eggs of Phthorimaea operculella, one day eggs and larvae of E. kuehniella, larvae of E. kuehniella and P. operculella and larvae of E. kuehniella only. Results obtained revealed that, the highest average daily consumption for each spider was recorded in case of feeding on eggs of P. operculella. While, the longest survival period was recorded in case of feeding on larvae of E. kuehniella.

  15. Biomimetic Spider Leg Joints: A Review from Biomechanical Research to Compliant Robotic Actuators

    Stefan Landkammer

    2016-07-01

    Full Text Available Due to their inherent compliance, soft actuated joints are becoming increasingly important for robotic applications, especially when human-robot-interactions are expected. Several of these flexible actuators are inspired by biological models. One perfect showpiece for biomimetic robots is the spider leg, because it combines lightweight design and graceful movements with powerful and dynamic actuation. Building on this motivation, the review article focuses on compliant robotic joints inspired by the function principle of the spider leg. The mechanism is introduced by an overview of existing biological and biomechanical research. Thereupon a classification of robots that are bio-inspired by spider joints is presented. Based on this, the biomimetic robot applications referring to the spider principle are identified and discussed.

  16. The use of tetragnathid spiders as bioindicators of metal exposure at a coal ash spill site.

    Otter, Ryan R; Hayden, Mary; Mathews, Teresa; Fortner, Allison; Bailey, Frank C

    2013-09-01

    On 22 December 2008, a dike containing coal fly ash from the Tennessee Valley Authority Kingston Fossil Fuel Plant (TN, USA) failed, resulting in the largest coal ash spill in US history. The present study was designed to determine sediment metal concentrations at multiple site locations and to determine whether site-specific bioaccumulation of metals existed in tetragnathid spiders. Selenium and nickel were the only 2 metals to exceed the US Environmental Protection Agency sediment screening levels. Selenium concentrations in spiders were significantly higher at ash-affected sites than in those from reference sites. The ratio of methylmercury to total mercury in spiders was found to be similar to that in other organisms (65-75%), which highlights the potential use of tetragnathid spiders as an indicator species for tracing contaminant transfer between the aquatic and terrestrial ecosystems. Copyright © 2013 SETAC.

  17. Efficacy of DNA barcoding for the species identification of spiders from Western Ghats of India.

    Gaikwad, Swapnil; Warudkar, Ashwin; Shouche, Yogesh

    2017-09-01

    DNA barcoding has emerged as an additional tool for taxonomy and as an aid to taxonomic impediments. Due to their extensive morphological variation, spiders are taxonomically challenging. Therefore, all over the world, attempts are being made to DNA barcode species of spiders. Till now no attempts were made to DNA barcode Indian spiders despite their rich diversity. We have generated DNA barcodes for 60 species (n = 112) of spiders for the first time from India. Although only 17 species were correctly identified at the species level, DNA barcoding correctly discriminated 99% of the species studied here. We have also found high intraspecies nucleotide divergence in Plexippus paykulli suggesting cryptic diversity that needs to be studied in detail. Our study also showed non-specific amplification of the Cytochrome Oxidase I (COI) gene of endosymbiont bacteria Wolbachia. However, these cases are very rare and could be resolved by the use of modified or group specific primers.

  18. Captive spider monkeys (Ateles geoffroyi) arm-raise to solicit allo-grooming.

    Scheel, Matthew H; Edwards, Dori

    2012-03-01

    Old World monkeys solicit allo-grooming from conspecifics. However, there are relatively few studies of allo-grooming among spider monkeys, and descriptions of allo-grooming solicitation among spider monkeys are anecdotal. In this study, eighty-one hours of video, shot over eight weeks, captured 271 allo-grooming bouts among small groups of captive spider monkeys. Six of eight monkeys made heretofore unreported arm-raises that solicited higher than normal rates of allo-grooming. Allo-grooming bout durations following arm-raises also tended to be longer than bouts not preceded by arm-raises. The efficacy of the arm-raise at soliciting allo-grooming suggests spider monkeys are capable of intentional communication. Copyright © 2012 Elsevier B.V. All rights reserved.

  19. Investigating the influence of farm-scape geospatial characteristics on spider diversity

    Biodiversity is an important aspect of sustainable crop management and agricultural production. Maintaining biodiversity within agricultural ecosystems, especially in regards to predator species, promotes natural pest control and many other ecosystem services. Spiders (Araneae) often prey upon commo...

  20. Prediction of abundance of forest spiders according to climate warming in South Korea

    Tae-Sung Kwon

    2014-06-01

    Full Text Available Distribution of spiders will be changed as climate warms. Abundance of spider species was predicted nationwide in South Korea. Abundance of spiders was projected using temperature species distribution model based on a nationwide data (366 forest sites according to climate change scenario RCP 4.5 and 8.5. The model predicts that 9 out of 17 species will increase in abundance while 8 species will decrease. Based on this finding, a qualitative prediction (increase or decrease was conducted on the species with more than 1% occurrence: 68 species are expected to decrease, 9 to increase, and 8 to change a little. In pooled estimation, 76 species (75% are expected to decrease, 18 species (18% to increase, and by 8 species (8% to have little change. The projection indicates that majority of spider species will decrease, but minority of species will increase as climate warms, suggesting great increase of remained species in lowlands.

  1. Intersexual Trophic Niche Partitioning in an Ant-Eating spider (Araneae: Zodariidae)

    Pekár, Stanislav; Martisová, Martina; Bilde, T.

    2011-01-01

    lead to higher energy demands in females driven by fecundity selection, while males invest in mate searching. We tested predictions of the two hypotheses underlying intersexual trophic niche partitioning in a natural population of spiders. Zodarion jozefienae spiders specialize on Messor barbarus ants...... that are polymorphic in body size and hence comprise potential trophic niches for the spider, making this system well-suited to study intersexual trophic niche partitioning. Methodology/Principal Findings Comparative analysis of trophic morphology (the chelicerae) and body size of males, females and juveniles...... demonstrated highly female biased SSD (Sexual Size Dimorphism) in body size, body weight, and in the size of chelicerae, the latter arising from sex-specific growth patterns in trophic morphology. In the field, female spiders actively selected ant sub-castes that were larger than the average prey size...

  2. Mobile Game Probes

    Borup Lynggaard, Aviaja

    2006-01-01

    This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....

  3. Spider fauna of semi-dry grasslands on a military training base in Northwest Germany (Münster

    Buchholz, Sascha

    2008-07-01

    Full Text Available The spider fauna of semi-dry grasslands on the military training area of Dorbaum near Münster (North Rhine-Westphalia was investigated. From 2002 to 2003 a total of 11,194 mature spiders from 141 species and 20 families was caught by pitfall trapping and hand sampling. Among them are 18 species listed in the Red Data Book of North Rhine-Westphalia, four species are rare or previously rarely recorded. Most of the spiders are habitat generalists that extend their occurrence into all types of habitats, while the number of species which are stenotopic to sand habitats is noticeably low (n = 13. The spider data were analysed with Principal Component Analysis (PCA. It is possible to distinguish spider communities of neighbouring forested habitats from species groups of open habitats, but there is no uniform spider community which is characteristic for semi-dry grassland.

  4. Coagulopathy after spider bites in a six-year-old boy

    Ansari SH.

    2008-06-01

    Full Text Available Background: Spider bites are common in most parts of the world. In some areas, where snake or scorpion bites are common, spider bites may not be considered a significant problem by the general public and those who have been bitten by spiders may not go to a hospital. However, significant problems are observed in the victims of certain species of spiders including: widow spider (of the genus Latrodectus, including the black widow and brown spiders (of the genus Loxosceles, such as the brown recluse. Case: We report a six-year-old boy, admitted to the hospital two weeks after suffering a spider bite. The patient presented with a severe nose bleed, ecchymosis and purpura, as well as anemia, indicating a clotting disorder. Laboratory results revealed abnormal values for prothrombin time (PT >50 sec, partial thromboplastin time (PTT >120 min and fibrinogen = 0 mg/dl, whereas factor VIII was normal according to a mixing study, with a normal platelet count of 350,000/µl. The patient was managed with fresh frozen plasma every 12 h, and was discharged one week after hospital admission. At present, the patient is well with more normal laboratory results one month after treatment: PT=13.4 sec, PTT= 34 sec, fibrinogen=105 mg/dl.         Conclusions: Although spider bites are uncommon in Iran, severe systemic reactions may occur in the pediatric population requiring admission to the pediatric intensive care unit. These systemic reactions may include hemolytic anemia coagulopathy and renal failure.

  5. Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems

    Kraus, Johanna M.; Gibson, Polly P.; Walters, David M.; Mills, Marc A.

    2017-01-01

    Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems.However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI,USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r2> 0.78) and had similar mean ΣPCB concentrations when averaged acrossall years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa lesseffective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2016;9999:1–9. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

  6. The functional morphology of color changing in a spider: development of ommochrome pigment granules.

    Insausti, Teresita C; Casas, Jérôme

    2008-03-01

    Studies on the formation of ommochrome pigment granules are very few, despite their generalized occurrence as screening pigments in insect eyes. This is particularly true for ommochrome granules responsible for epidermal coloration. The aims of this study were to characterize the localization of major body pigments in a color changing mimetic spider, Misumena vatia (Thomisidae), and to describe the formation and location of ommochrome pigment granules responsible for the spider's color change from white to yellow. The unpigmented cuticula of this spider is transparent. Both the guanine localized in guanine cells in the opisthosoma and the uric acid localized in epidermis cells in the prosoma are responsible for the white coloration. The bright yellow color is due to the combination of ommochrome pigment granules and the white reflectance from coincident guanine and/or uric acid. The formation of ommochrome pigment granules in epidermis cells proceeds via three distinctive steps. Translucent, UV fluorescent, progranules (type I) are produced by a dense network of endoplasmic reticulum associated with numerous mitochondria and glycogen rosettes. These progranules are present in white spiders only, and regularly distributed in the cytoplasm. The merging of several progranules of type I into a transient state (progranule type II) leads to the formation of granules (type III) characterized by their lack of fluorescence, their spherical sections and their osmophilic-electron-dense contents. They are found in yellow spiders and in the red stripes on the body sides. Their color varies from yellow to red. Thus, white spiders contain only type I granules, yellow tinted spiders contain type II and III granules and bright yellow spiders contain only type III granules. We present a synthetic view of the ontogeny of ommochrome granules. We discuss the physiology of color changing and the nature of the chemical compounds in the different types of granules. Extended studies on the

  7. Riparian spiders as sentinels of polychlorinated biphenyl contamination across heterogeneous aquatic ecosystems.

    Kraus, Johanna M; Gibson, Polly P; Walters, David M; Mills, Marc A

    2017-05-01

    Riparian spiders are being used increasingly to track spatial patterns of contaminants in and fluxing from aquatic ecosystems. However, our understanding of the circumstances under which spiders are effective sentinels of aquatic pollution is limited. The present study tests the hypothesis that riparian spiders may be effectively used to track spatial patterns of sediment pollution by polychlorinated biphenyls (PCBs) in aquatic ecosystems with high habitat heterogeneity. The spatial pattern of ΣPCB concentrations in 2 common families of riparian spiders sampled in 2011 to 2013 generally tracked spatial variation in sediment ΣPCBs across all sites within the Manistique River Great Lakes Area of Concern (AOC), a rivermouth ecosystem located on the south shore of the Upper Peninsula, Manistique (MI, USA) that includes harbor, river, backwater, and lake habitats. Sediment ΣPCB concentrations normalized for total organic carbon explained 41% of the variation in lipid-normalized spider ΣPCB concentrations across 11 sites. Furthermore, 2 common riparian spider taxa (Araneidae and Tetragnathidae) were highly correlated (r 2  > 0.78) and had similar mean ΣPCB concentrations when averaged across all years. The results indicate that riparian spiders may be useful sentinels of relative PCB availability to aquatic and riparian food webs in heterogeneous aquatic ecosystems like rivermouths where habitat and contaminant variability may make the use of aquatic taxa less effective. Furthermore, the present approach appears robust to heterogeneity in shoreline development and riparian vegetation that support different families of large web-building spiders. Environ Toxicol Chem 2017;36:1278-1286. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in the public domain in the United States of America. Published 2016 Wiley Periodicals, Inc. on behalf of SETAC. This article is a US government work and, as such, is in

  8. Record breaking achievements by spiders and the scientists who study them.

    Mammola, Stefano; Michalik, Peter; Hebets, Eileen A; Isaia, Marco

    2017-01-01

    Organismal biology has been steadily losing fashion in both formal education and scientific research. Simultaneous with this is an observable decrease in the connection between humans, their environment, and the organisms with which they share the planet. Nonetheless, we propose that organismal biology can facilitate scientific observation, discovery, research, and engagement, especially when the organisms of focus are ubiquitous and charismatic animals such as spiders. Despite being often feared, spiders are mysterious and intriguing, offering a useful foundation for the effective teaching and learning of scientific concepts and processes. In order to provide an entryway for teachers and students-as well as scientists themselves-into the biology of spiders, we compiled a list of 99 record breaking achievements by spiders (the "Spider World Records"). We chose a world-record style format, as this is known to be an effective way to intrigue readers of all ages. We highlighted, for example, the largest and smallest spiders, the largest prey eaten, the fastest runners, the highest fliers, the species with the longest sperm, the most venomous species, and many more. We hope that our compilation will inspire science educators to embrace the biology of spiders as a resource that engages students in science learning. By making these achievements accessible to non-arachnologists and arachnologists alike, we suggest that they could be used: (i) by educators to draw in students for science education, (ii) to highlight gaps in current organismal knowledge, and (iii) to suggest novel avenues for future research efforts. Our contribution is not meant to be comprehensive, but aims to raise public awareness on spiders, while also providing an initial database of their record breaking achievements.

  9. Web building and silk properties functionally covary among species of wolf spider.

    Lacava, Mariángeles; Camargo, Arley; Garcia, Luis F; Benamú, Marco A; Santana, Martin; Fang, Jian; Wang, Xungai; Blamires, Sean J

    2018-04-15

    Although phylogenetic studies have shown covariation between the properties of spider major ampullate (MA) silk and web building, both spider webs and silks are highly plastic so we cannot be sure whether these traits functionally covary or just vary across environments that the spiders occupy. As MaSp2-like proteins provide MA silk with greater extensibility, their presence is considered necessary for spider webs to effectively capture prey. Wolf spiders (Lycosidae) are predominantly non-web building, but a select few species build webs. We accordingly collected MA silk from two web-building and six non-web-building species found in semirural ecosystems in Uruguay to test whether the presence of MaSp2-like proteins (indicated by amino acid composition, silk mechanical properties and silk nanostructures) was associated with web building across the group. The web-building and non-web-building species were from disparate subfamilies so we estimated a genetic phylogeny to perform appropriate comparisons. For all of the properties measured, we found differences between web-building and non-web-building species. A phylogenetic regression model confirmed that web building and not phylogenetic inertia influences silk properties. Our study definitively showed an ecological influence over spider silk properties. We expect that the presence of the MaSp2-like proteins and the subsequent nanostructures improves the mechanical performance of silks within the webs. Our study furthers our understanding of spider web and silk co-evolution and the ecological implications of spider silk properties. © 2018 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2018 European Society For Evolutionary Biology.

  10. Linking Native and Invader Traits Explains Native Spider Population Responses to Plant Invasion.

    Jennifer N Smith

    Full Text Available Theoretically, the functional traits of native species should determine how natives respond to invader-driven changes. To explore this idea, we simulated a large-scale plant invasion using dead spotted knapweed (Centaurea stoebe stems to determine if native spiders' web-building behaviors could explain differences in spider population responses to structural changes arising from C. stoebe invasion. After two years, irregular web-spiders were >30 times more abundant and orb weavers were >23 times more abundant on simulated invasion plots compared to controls. Additionally, irregular web-spiders on simulated invasion plots built webs that were 4.4 times larger and 5.0 times more likely to capture prey, leading to >2-fold increases in recruitment. Orb-weavers showed no differences in web size or prey captures between treatments. Web-spider responses to simulated invasion mimicked patterns following natural invasions, confirming that C. stoebe's architecture is likely the primary attribute driving native spider responses to these invasions. Differences in spider responses were attributable to differences in web construction behaviors relative to historic web substrate constraints. Orb-weavers in this system constructed webs between multiple plants, so they were limited by the overall quantity of native substrates but not by the architecture of individual native plant species. Irregular web-spiders built their webs within individual plants and were greatly constrained by the diminutive architecture of native plant substrates, so they were limited both by quantity and quality of native substrates. Evaluating native species traits in the context of invader-driven change can explain invasion outcomes and help to identify factors limiting native populations.

  11. On Graceful Spider Graphs with at Most Four Legs of Lengths Greater than One

    A. Panpa

    2016-01-01

    Full Text Available A graceful labeling of a tree T with n edges is a bijection f:V(T→{0,1,2,…,n} such that {|f(u-f(v|:uv∈E(T} equal to {1,2,…,n}. A spider graph is a tree with at most one vertex of degree greater than 2. We show that all spider graphs with at most four legs of lengths greater than one admit graceful labeling.

  12. Characterisation of protein families in spider digestive fluids and their role in extra-oral digestion.

    Walter, André; Bechsgaard, Jesper; Scavenius, Carsten; Dyrlund, Thomas S; Sanggaard, Kristian W; Enghild, Jan J; Bilde, Trine

    2017-08-10

    Spiders are predaceous arthropods that are capable of subduing and consuming relatively large prey items compared to their own body size. For this purpose, spiders have evolved potent venoms to immobilise prey and digestive fluids that break down nutrients inside the prey's body by means of extra-oral digestion (EOD). Both secretions contain an array of active proteins, and an overlap of some components has been anecdotally reported, but not quantified. We systematically investigated the extent of such protein overlap. As venom injection and EOD succeed each other, we further infer functional explanations, and, by comparing two spider species belonging to different clades, assess its adaptive significance for spider EOD in general. We describe the protein composition of the digestive fluids of the mygalomorph Acanthoscurria geniculata and the araneomorph Stegodyphus mimosarum, in comparison with previously published data on a third spider species. We found a number of similar hydrolases being highly abundant in all three species. Among them, members of the family of astacin-like metalloproteases were particularly abundant. While the importance of these proteases in spider venom and digestive fluid was previously noted, we now highlight their widespread use across different spider taxa. Finally, we found species specific differences in the protein overlap between venom and digestive fluid, with the difference being significantly greater in S. mimosarum compared to A. geniculata. The injection of venom precedes the injection with digestive fluid, and the overlap of proteins between venom and digestive fluid suggests an early involvement in EOD. Species specific differences in the overlap may reflect differences in ecology between our two study species. The protein composition of the digestive fluid of all the three species we compared is highly similar, suggesting that the cocktail of enzymes is highly conserved and adapted to spider EOD.

  13. Peptidomic and transcriptomic profiling of four distinct spider venoms.

    Vera Oldrati

    Full Text Available Venom based research is exploited to find novel candidates for the development of innovative pharmacological tools, drug candidates and new ingredients for cosmetic and agrochemical industries. Moreover, venomics, as a well-established approach in systems biology, helps to elucidate the genetic mechanisms of the production of such a great molecular biodiversity. Today the advances made in the proteomics, transcriptomics and bioinformatics fields, favor venomics, allowing the in depth study of complex matrices and the elucidation even of minor compounds present in minute biological samples. The present study illustrates a rapid and efficient method developed for the elucidation of venom composition based on NextGen mRNA sequencing of venom glands and LC-MS/MS venom proteome profiling. The analysis of the comprehensive data obtained was focused on cysteine rich peptide toxins from four spider species originating from phylogenetically distant families for comparison purposes. The studied species were Heteropoda davidbowie (Sparassidae, Poecilotheria formosa (Theraphosidae, Viridasius fasciatus (Viridasiidae and Latrodectus mactans (Theridiidae. This led to a high resolution profiling of 284 characterized cysteine rich peptides, 111 of which belong to the Inhibitor Cysteine Knot (ICK structural motif. The analysis of H. davidbowie venom revealed a high richness in term of venom diversity: 95 peptide sequences were identified; out of these, 32 peptides presented the ICK structural motif and could be classified in six distinct families. The profiling of P. formosa venom highlighted the presence of 126 peptide sequences, with 52 ICK toxins belonging to three structural distinct families. V. fasciatus venom was shown to contain 49 peptide sequences, out of which 22 presented the ICK structural motif and were attributed to five families. The venom of L. mactans, until now studied for its large neurotoxins (Latrotoxins, revealed the presence of 14

  14. Evaluation of the efficacy of vacuum cleaners for the integrated control of brown spider Loxosceles intermedia

    E. N. Ramires

    2007-01-01

    Full Text Available Some venomous spiders of the genus Loxosceles can reach high population densities inside and around houses. In Brazil, most spider accidents are related to Loxosceles intermedia. Control of loxoscelism should utilize integrated pest management tools, such as vacuum cleaners, to eliminate egg sacs, webs and spiders. The present study tested the efficacy of one type of vacuum cleaner (for professional and domestic use in the control of L. intermedia populations. Cockroaches (Pycnoscelus surinamensis were used in some tests for comparison. Vacuuming using standard accessories or a paper tube resulted in the death of all female (n=60, male (n=60, young (n=60 and just-hatched (n=60 L. intermedia, and all egg sacs (n=5 were destroyed. The removal of the plastic plate present at the bottom of the vacuuming tube inside the machine allowed some spiders to survive the vacuuming process. When kept inside a vacuum bag full of dust and debris, adult females (n=10 survived for 10 days; however, significant mortality was observed among male (n=10 and young individuals (n=10. Addition of cornstarch to the vacuum bag did not affect the spiders (n=20. Vacuum cleaners, such as the one used in the present investigation, are promising tools for integrated management of L. intermedia and other spiders in domestic environments.

  15. Local and Landscape Correlates of Spider Activity Density and Species Richness in Urban Gardens.

    Otoshi, Michelle D; Bichier, Peter; Philpott, Stacy M

    2015-08-01

    Urbanization is a major threat to arthropod biodiversity and abundance due to reduction and loss of suitable natural habitat. Green spaces and small-scale agricultural areas may provide habitat and resources for arthropods within densely developed cities. We studied spider activity density (a measure of both abundance and degree of movement) and diversity in urban gardens in Santa Cruz, Santa Clara, and Monterey counties in central California, USA. We sampled for spiders with pitfall traps and sampled 38 local site characteristics for 5 mo in 19 garden sites to determine the relative importance of individual local factors. We also analyzed 16 landscape variables at 500-m and 1-km buffers surrounding each garden to determine the significance of landscape factors. We identified individuals from the most common families to species and identified individuals from other families to morphospecies. Species from the families Lycosidae and Gnaphosidae composed 81% of total adult spider individuals. Most of the significant factors that correlated with spider activity density and richness were local rather than landscape factors. Spider activity density and richness increased with mulch cover and flowering plant species, and decreased with bare soil. Thus, changes in local garden management have the potential to promote diversity of functionally important spiders in urban environments. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  16. Geophagy in brown spider monkeys (Ateles hybridus) in a lowland tropical rainforest in Colombia.

    Link, Andres; de Luna, Ana Gabriela; Arango, Ricardo; Diaz, Maria Clara

    2011-01-01

    Spider monkeys and howler monkeys are the only Neotropical primates that eat soil from mineral licks. Not all species within these genera visit mineral licks, and geophagy has been restricted to populations of Ateles belzebuth belzebuth,Ateles belzebuth chamek and Alouatta seniculus in western Amazonian rainforests. With the aid of a camera trap we studied the visitation patterns of a group of brown spider monkeys (Ateles hybridus) to a mineral lick at Serrania de Las Quinchas, in Colombia. Spider monkeys visited the lick frequently throughout the year, with a monthly average of 21.7 ± 7.2 visits per 100 days of camera trapping (n = 14 months). Spider monkeys visited the mineral lick almost always on days with no rain, or very little (<3 mm) rain, suggesting that proximate environmental variables might determine spider monkeys' decisions to come to the ground at the licks. This study expands the geographical occurrence of mineral lick use by spider monkeys providing additional data for future assessments on the biogeographical correlates of mineral lick use by platyrrhines. Copyright © 2011 S. Karger AG, Basel.

  17. Whiteflies interfere with indirect plant defense against spider mites in Lima bean

    Zhang, Peng-Jun; Zheng, Si-Jun; van Loon, Joop J. A.; Boland, Wilhelm; David, Anja; Mumm, Roland; Dicke, Marcel

    2009-01-01

    Plants under herbivore attack are able to initiate indirect defense by synthesizing and releasing complex blends of volatiles that attract natural enemies of the herbivore. However, little is known about how plants respond to infestation by multiple herbivores, particularly if these belong to different feeding guilds. Here, we report the interference by a phloem-feeding insect, the whitefly Bemisia tabaci, with indirect plant defenses induced by spider mites (Tetranychus urticae) in Lima bean (Phaseolus lunatus) plants. Additional whitefly infestation of spider-mite infested plants resulted in a reduced attraction of predatory mites (Phytoseiulus persimilis) compared to attraction to plants infested by spider mites only. This interference is shown to result from the reduction in (E)-β-ocimene emission from plants infested by both spider mites and whiteflies. When using exogenous salicylic acid (SA) application to mimic B. tabaci infestation, we observed similar results in behavioral and chemical analyses. Phytohormone and gene-expression analyses revealed that B. tabaci infestation, as well as SA application, inhibited spider mite-induced jasmonic acid (JA) production and reduced the expression of two JA-regulated genes, one of which encodes for the P. lunatus enzyme β-ocimene synthase that catalyzes the synthesis of (E)-β-ocimene. Remarkably, B. tabaci infestation concurrently inhibited SA production induced by spider mites. We therefore conclude that in dual-infested Lima bean plants the suppression of the JA signaling pathway by whitefly feeding is not due to enhanced SA levels. PMID:19965373

  18. Social makes smart: rearing conditions affect learning and social behaviour in jumping spiders.

    Liedtke, J; Schneider, J M

    2017-11-01

    There is a long-standing debate as to whether social or physical environmental aspects drive the evolution and development of cognitive abilities. Surprisingly few studies make use of developmental plasticity to compare the effects of these two domains during development on behaviour later in life. Here, we present rearing effects on the development of learning abilities and social behaviour in the jumping spider Marpissa muscosa. These spiders are ideally suited for this purpose because they possess the ability to learn and can be reared in groups but also in isolation without added stress. This is a critical but rarely met requirement for experimentally varying the social environment to test its impact on cognition. We split broods of spiders and reared them either in a physically or in a socially enriched environment. A third group kept under completely deprived conditions served as a 'no-enrichment' control. We tested the spiders' learning abilities by using a modified T-maze. Social behaviour was investigated by confronting spiders with their own mirror image. Results show that spiders reared in groups outperform their conspecifics from the control, i.e. 'no-enrichment', group in both tasks. Physical enrichment did not lead to such an increased performance. We therefore tentatively suggest that growing up in contact with conspecifics induces the development of cognitive abilities in this species.

  19. Herbivory in spiders: the importance of pollen for orb-weavers.

    Eggs, Benjamin; Sanders, Dirk

    2013-01-01

    Orb-weaving spiders (Araneidae) are commonly regarded as generalist insect predators but resources provided by plants such as pollen may be an important dietary supplementation. Their webs snare insect prey, but can also trap aerial plankton like pollen and fungal spores. When recycling their orb webs, the spiders may therefore also feed on adhering pollen grains or fungal spores via extraoral digestion. In this study we measured stable isotope ratios in the bodies of two araneid species (Aculepeira ceropegia and Araneus diadematus), their potential prey and pollen to determine the relative contribution of pollen to their diet. We found that about 25% of juvenile orb-weaving spiders' diet consisted of pollen, the other 75% of flying insects, mainly small dipterans and hymenopterans. The pollen grains in our study were too large to be taken up accidentally by the spiders and had first to be digested extraorally by enzymes in an active act of consumption. Therefore, pollen can be seen as a substantial component of the spiders' diet. This finding suggests that these spiders need to be classified as omnivores rather than pure carnivores.

  20. Stable isotopes of Hawaiian spiders reflect substrate properties along a chronosequence

    Dawson, Todd E.; Gillespie, Rosemary G.

    2018-01-01

    The Hawaiian Islands offer a unique opportunity to test how changes in the properties of an isolated ecosystem are propagated through the organisms that occur within that ecosystem. The age-structured arrangement of volcanic-derived substrates follows a regular progression over space and, by inference, time. We test how well documented successional changes in soil chemistry and associated vegetation are reflected in organisms at higher trophic levels—specifically, predatory arthropods (spiders)—across a range of functional groups. We focus on three separate spider lineages: one that builds capture webs, one that hunts actively, and one that specializes on eating other spiders. We analyze spiders from three sites across the Hawaiian chronosequence with substrate ages ranging from 200 to 20,000 years. To measure the extent to which chemical signatures of terrestrial substrates are propagated through higher trophic levels, we use standard stable isotope analyses of nitrogen and carbon, with plant leaves included as a baseline. The target taxa show the expected shift in isotope ratios of δ15N with trophic level, from plants to cursorial spiders to web-builders to spider eaters. Remarkably, organisms at all trophic levels also precisely reflect the successional changes in the soil stoichiometry of the island chronosequence, demonstrating how the biogeochemistry of the entire food web is determined by ecosystem succession of the substrates on which the organisms have evolved. PMID:29576984

  1. Dangerous mating systems: signal complexity, signal content and neural capacity in spiders.

    Herberstein, M E; Wignall, A E; Hebets, E A; Schneider, J M

    2014-10-01

    Spiders are highly efficient predators in possession of exquisite sensory capacities for ambushing prey, combined with machinery for launching rapid and determined attacks. As a consequence, any sexually motivated approach carries a risk of ending up as prey rather than as a mate. Sexual selection has shaped courtship to effectively communicate the presence, identity, motivation and/or quality of potential mates, which help ameliorate these risks. Spiders communicate this information via several sensory channels, including mechanical (e.g. vibrational), visual and/or chemical, with examples of multimodal signalling beginning to emerge in the literature. The diverse environments that spiders inhabit have further shaped courtship content and form. While our understanding of spider neurobiology remains in its infancy, recent studies are highlighting the unique and considerable capacities of spiders to process and respond to complex sexual signals. As a result, the dangerous mating systems of spiders are providing important insights into how ecology shapes the evolution of communication systems, with future work offering the potential to link this complex communication with its neural processes. Copyright © 2014 Elsevier Ltd. All rights reserved.

  2. Parasitism of Trombidium brevimanum larvae on agrobiont linyphiid spiders from Germany.

    Tomić, Vladimir; Mąkol, Joanna; Stamenković, Srdjan; Büchs, Wolfgang; Prescher, Sabine; Sivčev, Ivan; Graora, Draga; Sivčev, Lazar; Gotlin-Čuljak, Tatjana; Dudić, Boris

    2015-08-01

    An experiment on three differently-managed agricultural fields in Ahlum, Germany, which aimed at establishing the impact of different management systems on the biodiversity of predators and decomposers, yielded a significant number of spiders parasitized by larvae of Trombidium brevimanum (Actinotrichida, Parasitengona, Trombidiidae). Spider data from the whole sampling period (September 2010-July 2012), indicated that ectoparasitic larvae were recorded only on spiders in pitfall traps in the period of June-July 2011. In this period, only eight species of Linyphiidae--out of 42 species assigned to nine spider families recorded from the study area--were parasitized by mites; considerable levels of parasitism were recorded on Erigone atra, E. dentipalpis, and Oedothorax apicatus. The highest prevalence of parasitism was recorded on the organic field for E. atra (29%), while on the integrated and conventional fields significantly fewer parasitized spiders were observed. The preferred attachment sites on the spider host were regions with softer cuticle, especially regions on the carapace and on the abdomen, adjacent to the pedicel.

  3. Plasticity in Major Ampullate Silk Production in Relation to Spider Phylogeny and Ecology

    Boutry, Cecilia; Řezáč, Milan; Blackledge, Todd Alan

    2011-01-01

    Spider major ampullate silk is a high-performance biomaterial that has received much attention. However, most studies ignore plasticity in silk properties. A better understanding of silk plasticity could clarify the relative importance of chemical composition versus processing of silk dope for silk properties. It could also provide insight into how control of silk properties relates to spider ecology and silk uses. We compared silk plasticity (defined as variation in the properties of silk spun by a spider under different conditions) between three spider clades in relation to their anatomy and silk biochemistry. We found that silk plasticity exists in RTA clade and orbicularian spiders, two clades that differ in their silk biochemistry. Orbiculariae seem less dependent on external spinning conditions. They probably use a valve in their spinning duct to control friction forces and speed during spinning. Our results suggest that plasticity results from different processing of the silk dope in the spinning duct. Orbicularian spiders seem to display better control of silk properties, perhaps in relation to their more complex spinning duct valve. PMID:21818328

  4. The embryonic origin of the ampullate silk glands of the spider Cupiennius salei.

    Hilbrant, Maarten; Damen, Wim G M

    2015-05-01

    Silk production in spiders is considered a key innovation, and to have been vital for the diversification of the clade. The evolutionary origin of the organs involved in spider silk production, however, and in particular of the silk glands, is poorly understood. Homologies have been proposed between these and other glands found in arachnids, but lacking knowledge of the embryonic development of spider silk glands hampers an evaluation of hypotheses. This study focuses on the embryonic origin of the largest silk glands of the spider Cupiennius salei, the major and minor ampullate glands. We show how the ampullate glands originate from ectodermal invaginations on the embryonic spinneret limb buds, in relation to morphogenesis of these buds. Moreover, we visualize the subsequent growth of the ampullate glands in sections of the early postembryonic stages. The invaginations are shown to correlate with expression of the proneural gene CsASH2, which is remarkable since it has been proposed that spider silk glands and their nozzles originate from sensory bristles. Hence, by confirming the ectodermal origin of spider silk glands, and by describing the (post-)embryonic morphogenesis of the ampullate glands, this work provides a starting point for further investigating into the genetic program that underlies their development. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Plasticity in major ampullate silk production in relation to spider phylogeny and ecology.

    Cecilia Boutry

    Full Text Available Spider major ampullate silk is a high-performance biomaterial that has received much attention. However, most studies ignore plasticity in silk properties. A better understanding of silk plasticity could clarify the relative importance of chemical composition versus processing of silk dope for silk properties. It could also provide insight into how control of silk properties relates to spider ecology and silk uses. We compared silk plasticity (defined as variation in the properties of silk spun by a spider under different conditions between three spider clades in relation to their anatomy and silk biochemistry. We found that silk plasticity exists in RTA clade and orbicularian spiders, two clades that differ in their silk biochemistry. Orbiculariae seem less dependent on external spinning conditions. They probably use a valve in their spinning duct to control friction forces and speed during spinning. Our results suggest that plasticity results from different processing of the silk dope in the spinning duct. Orbicularian spiders seem to display better control of silk properties, perhaps in relation to their more complex spinning duct valve.

  6. A verified spider bite and a review of the literature confirm Indian ornamental tree spiders (Poecilotheria species) as underestimated theraphosids of medical importance.

    Fuchs, Joan; von Dechend, Margot; Mordasini, Raffaella; Ceschi, Alessandro; Nentwig, Wolfgang

    2014-01-01

    Literature on bird spider or tarantula bites (Theraphosidae) is rare. This is astonishing as they are coveted pets and interaction with their keepers (feeding, cleaning the terrarium or taking them out to hold) might increase the possibility for bites. Yet, this seems to be a rare event and might be why most theraphosids are considered to be harmless, even though the urticating hairs of many American species can cause disagreeable allergic reactions. We are describing a case of a verified bite by an Indian ornamental tree spider (Poecilotheria regalis), where the patient developed severe, long lasting muscle cramps several hours after the bite. We present a comprehensive review of the literature on bites of these beautiful spiders and conclude that a delayed onset of severe muscle cramps, lasting for days, is characteristic for Poecilotheria bites. We discuss Poecilotheria species as an exception from the general assumption that theraphosid bites are harmless to humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Ultra-high Thermal Conductivity of Spider Silk: Protein Function Study with Controlled Structure Change and Comparison

    2016-01-23

    induced increase in energy transport capacity of silkworm silks , Biopolymers , (10 2014): 0. doi: 10.1002/bip.22496 Shen Xu, Zaoli Xu, James Starrett...SECURITY CLASSIFICATION OF: In the past three years, we have conducted extensive research to study the structure of spider silks and investigate how the...manually spun spider silks demonstrates that the alignment of the antiparallel beta-sheet crystals in spider silks plays one of the most important

  8. Contributions of detrital subsidies to aboveground spiders during secondary succession, revealed by radiocarbon and stable isotope signatures.

    Haraguchi, Takashi F; Uchida, Masao; Shibata, Yasuyuki; Tayasu, Ichiro

    2013-04-01

    Prey subsidies originating from detritus add nutrients and energy to arboreal communities. Measurement of this subsidy is required in the understanding of how food web dynamics respond to changes in surrounding environments. Shrub spiders are one of the key predators involved in food web coupling. We evaluate the effects of potential changes in prey availabilities during secondary succession on the contribution of subsidy from detrital food webs to shrub spiders and how different spider feeding guilds used the subsidy of prey from detrital food webs. We measured the relative importance of the subsidy for the spider feeding guilds, using the ratios of stable isotopes of C (δ(13)C), and N (δ(15)N) and C isotope discrimination (Δ(14)C). Diet age was calculated from Δ(14)C values, because old diet ages of spiders indicate that the spiders consume prey from detrital food sources. Dominant aerial prey (Diptera) had a distinctively old diet age compared with arboreal prey, which indicates that aerial prey were subsidized from detrital food webs. Sit-and-wait spiders tended to have an older diet age than active hunting spiders, which indicates that sit-and-wait spiders depended more on subsidies. Diet age varied only slightly for spiders in stands of different ages, indicating that rates at which spiders use grazing and detrital prey are probably determined more by foraging strategies and not by stand age. A dominance of sit-and-wait predators will lead to higher detrital subsidy inputs in shrub habitats. This study highlights the effect of shrub spider community structure (feeding guild composition) on the volume of the subsidy received from the detrital food web.

  9. Glutamatergic postsynaptic block by Pamphobeteus spider venoms in crayfish.

    Araque, A; Ferreira, W; Lucas, S; Buño, W

    1992-01-31

    The effects of toxins from venom glands of two south american spiders (Pamphobeteus platyomma and P. soracabae) on glutamatergic excitatory synaptic transmission were studied in the neuromuscular junction of the opener muscle of crayfish. The toxins selectively and reversibly blocked both excitatory postsynaptic currents and potentials in a dose-dependent manner. They also reversibly abolished glutamate-induced postsynaptic membrane depolarization. They had no effect on resting postsynaptic membrane conductance nor on postsynaptic voltage-gated currents. The synaptic facilitation and the frequency of miniature postsynaptic potentials were unaffected by the toxins, indicating that presynaptic events were not modified. Picrotoxin, a selective antagonist of the gamma-aminobutyric acid (GABA)A receptor, did not modify toxin effects. We conclude that both toxins specifically block the postsynaptic glutamate receptor-channel complex.

  10. No discrimination against previous mates in a sexually cannibalistic spider

    Fromhage, Lutz; Schneider, Jutta M.

    2005-09-01

    In several animal species, females discriminate against previous mates in subsequent mating decisions, increasing the potential for multiple paternity. In spiders, female choice may take the form of selective sexual cannibalism, which has been shown to bias paternity in favor of particular males. If cannibalistic attacks function to restrict a male's paternity, females may have little interest to remate with males having survived such an attack. We therefore studied the possibility of female discrimination against previous mates in sexually cannibalistic Argiope bruennichi, where females almost always attack their mate at the onset of copulation. We compared mating latency and copulation duration of males having experienced a previous copulation either with the same or with a different female, but found no evidence for discrimination against previous mates. However, males copulated significantly shorter when inserting into a used, compared to a previously unused, genital pore of the female.

  11. Mapping Learning Outcomes and Assignment Tasks for SPIDER Activities

    Lyn Brodie

    2011-05-01

    Full Text Available Modern engineering programs have to address rapidly changing technical content and have to enable students to develop transferable skills such as critical evaluation, communication skills and lifelong learning. This paper introduces a combined learning and assessment activity that provides students with opportunities to develop and practice their soft skills, but also extends their theoretical knowledge base. Key tasks included self directed inquiry, oral and written communication as well as peer assessment. To facilitate the SPIDER activities (Select, Prepare and Investigate, Discuss, Evaluate, Reflect, a software tool has been implemented in the learning management system Moodle. Evidence shows increased student engagement and better learning outcomes for both transferable as well as technical skills. The study focuses on generalising the relationship between learning outcomes and assignment tasks as well as activities that drive these tasks. Trail results inform the approach. Staff evaluations and their views of assignments and intended learning outcomes also supported this analysis.

  12. Evolutionary Aspects of Acaricide-Resistance Development in Spider Mites

    Masahiro (Mh. Osakabe

    2009-01-01

    Full Text Available Although the development of acaricide resistance in spider mites is a long-standing issue in agricultural fields, recent problems with acaricide resistance may be characterized by the development of complex- and/or multiresistance to acaricides in distinct classes. Such complexity of resistance is not likely to be a single mechanism. Pesticide resistance involves the microevolution of arthropod pests, and population genetics underlies the evolution. In this review, we address the genetic mechanisms of acaricide resistance evolution. We discuss genetic diversity and linkage of resistance genes, relationships between mite habitat and dispersal, and the effect of dispersal on population genetic structure and the dynamics of resistance genes. Finally, we attempt to present a comprehensive view of acaricide resistance evolution and suggest risks under globalization as well as possible approaches to managing acaricide resistance evolution or emergence.

  13. Spiders (Araneae of stony debris in North Bohemia

    Růžička, Vlastimil

    1996-12-01

    Full Text Available The arachnofauna was studied at five stony debris sites in northern Bohemia. In Central Europe, the northern and montane species inhabiting cold places live not only on mountain tops and peat bogs but also on the lower edges of boulder debris, where air streaming through the system of inner compartments gives rise to an exceedingly cold microclimate. At such cold sites, spiders can live either on bare stones (Bathyphantes simillimus, Wubanoides uralensis, or in the rich layers of moss and lichen (Diplocentria bidentata. Kratochviliella bicapitata exhibits a diplostenoecious occurence in stony debris and on the tree bark. Latithorax faustus and Theonoe minutissima display diplostenoecious occurence in stony debris and on peat bogs. The occurence of the species Scotina celans in the Czech Republic was documented for the first time.

  14. David and Goliath: potent venom of an ant-eating spider (Araneae) enables capture of a giant prey

    Pekár, Stano; Šedo, Onřej; Líznarová, Eva; Korenko, Stanislav; Zdráhal, Zdeněk

    2014-07-01

    It is rare to find a true predator that repeatedly and routinely kills prey larger than itself. A solitary specialised ant-eating spider of the genus Zodarion can capture a relatively giant prey. We studied the trophic niche of this spider species and investigated its adaptations (behavioural and venomic) that are used to capture ants. We found that the spider captures mainly polymorphic Messor arenarius ants. Adult female spiders captured large morphs while tiny juveniles captured smaller morphs, yet in both cases ants were giant in comparison with spider size. All specimens used an effective prey capture strategy that protected them from ant retaliation. Juvenile and adult spiders were able to paralyse their prey using a single bite. The venom glands of adults were more than 50 times larger than those of juvenile spiders, but the paralysis latency of juveniles was 1.5 times longer. This suggests that this spider species possesses very potent venom already at the juvenile stage. Comparison of the venom composition between juvenile and adult spiders did not reveal significant differences. We discovered here that specialised capture combined with very effective venom enables the capture of giant prey.

  15. Habitat quality of the woolly spider monkey (Brachyteles hypoxanthus).

    da Silva Júnior, Wilson Marcelo; Alves Meira-Neto, João Augusto; da Silva Carmo, Flávia Maria; Rodrigues de Melo, Fabiano; Santana Moreira, Leandro; Ferreira Barbosa, Elaine; Dias, Luiz Gustavo; da Silva Peres, Carlos Augusto

    2009-01-01

    This study examines how habitat structure affects the home range use of a group of Brachyteles hypoxanthus in the Brigadeiro State Park, Brazil. It has been reported that most of the annual feeding time of woolly spider monkeys is spent eating leaves, but they prefer fruits when available. We hypothesise that the protein-to-fibre ratio (PF; best descriptor of habitat quality for folivorous primates) is a better descriptor of habitat quality and abundance for these primates than the structural attributes of forests (basal area is the best descriptor of habitat quality for frugivorous primates of Africa and Asia). We evaluated plant community structure, successional status, and PF of leaf samples from the dominant tree populations, both within the core and from a non-core area of the home range of our study group. Forest structure was a combination of stem density and basal area of dominant tree populations. The core area had larger trees, a higher forest basal area, and higher stem density than the non-core area. Mean PF did not differ significantly between these sites, although PF was influenced by differences in tree regeneration guilds. Large-bodied monkeys could be favoured by later successional stages of forests because larger trees and denser stems prevent the need for a higher expenditure of energy for locomotion as a consequence of vertical travel when the crowns of trees are disconnected in early successional forests. Forest structure variables (such as basal area of trees) driven by succession influence woolly spider monkey abundance in a fashion similar to frugivorous monkeys of Asia and Africa, and could explain marked differences in ranging behaviour and home range use by B. hypoxanthus. Copyright 2009 S. Karger AG, Basel.

  16. Nanostructure and molecular mechanics of spider dragline silk protein assemblies

    Keten, Sinan; Buehler, Markus J.

    2010-01-01

    Spider silk is a self-assembling biopolymer that outperforms most known materials in terms of its mechanical performance, despite its underlying weak chemical bonding based on H-bonds. While experimental studies have shown that the molecular structure of silk proteins has a direct influence on the stiffness, toughness and failure strength of silk, no molecular-level analysis of the nanostructure and associated mechanical properties of silk assemblies have been reported. Here, we report atomic-level structures of MaSp1 and MaSp2 proteins from the Nephila clavipes spider dragline silk sequence, obtained using replica exchange molecular dynamics, and subject these structures to mechanical loading for a detailed nanomechanical analysis. The structural analysis reveals that poly-alanine regions in silk predominantly form distinct and orderly beta-sheet crystal domains, while disorderly regions are formed by glycine-rich repeats that consist of 31-helix type structures and beta-turns. Our structural predictions are validated against experimental data based on dihedral angle pair calculations presented in Ramachandran plots, alpha-carbon atomic distances, as well as secondary structure content. Mechanical shearing simulations on selected structures illustrate that the nanoscale behaviour of silk protein assemblies is controlled by the distinctly different secondary structure content and hydrogen bonding in the crystalline and semi-amorphous regions. Both structural and mechanical characterization results show excellent agreement with available experimental evidence. Our findings set the stage for extensive atomistic investigations of silk, which may contribute towards an improved understanding of the source of the strength and toughness of this biological superfibre. PMID:20519206

  17. Spider fauna in Caspian Costal region of Iran.

    Ghavami, Sahra

    2007-03-01

    The current study investigated spider fauna of Caspian Costal region of Iran (Guilan, Mazandaran and Golestan provinces) during 2005-2006. Spiders were collected from on the ground and under the stones and grasses by bottle, aspirator, Pitfall trap and pans and from branches, leaves and trunks of different trees and bushes by Steiner and Baggiolini method and insect net. They transferred to the laboratory and classified in 52 species and 51 genera belonged to 20 families. Thirty species, 13 genera and 2 families are reported for the first time from Iran, as follows: Family Agelenidae: Agelena labyrinthica (Clerck, 1757), Cicurina sp., Family Araneidae: Agalenatea redii (Scopoli, 1763), Araniella inconspicua (Simon, 1874), Araniella alpica (C.L. Koch, 1869), Araneus diadematus Clerck, 1757, Cercidia sp., Cyclosa conica (Pallas, 1772), Hypsosinga sanguinea (C.L. Koch,1845), Family Clubionidae: Clubiona neglecta O.P. Camridge, 1862, Family Amaurobiidae, Family Eresidae: Eresus sp., Dresserus sp., Family Gnaphosidae: Aphantaulax sp., Micaria sp., Family Metidae: Zygiella x-notata (Clerck,1757), Family Miturgidae: Cheiracanthium erraticum (Walckenaer, 1802), Cheiracanthium pennyi O.P. Cambridge, 1873, Family Linyphiidae: Microlinyphia sp., Family Lycosidae: Alopecosa pulverulenta (Clerck, 1757), Pardosa amentata (Clerck, 1757), Pardosa agrestis (Westring, 1861), Pardosa monticola (Clerck, 1757), Family Oxyopidae: Oxyopes salticus (Hentx, 1802), Family Philodromidae: Philodromus cespitum (Walckenaer, 1802),Family Pholcidae: Psilochorus simoni (Berland, 1911), Pholcus phalangioides (Fuesslin, 1775), Family Salticidae: Salticus scenicus (Clerck, 1757), Family Tetragnathidae: Tetragnatha montana, Simon, 1874, Tetragnatha javana (Thorell, 1890), Family Theridiidae: Dipoena prona (Menge, 1868), Steatoda albomaculata (Degeer, 1778), Theridion impressum C. L. Koch, Theridion simile C.L. Koch,1836, Family Thomisidae: Misumena vatia (Clerck, 1757), Thanatus formicinus (Clerck

  18. Securing Paternity by Mutilating Female Genitalia in Spiders.

    Mouginot, Pierick; Prügel, Josepha; Thom, Ulrike; Steinhoff, Philip O M; Kupryjanowicz, Janusz; Uhl, Gabriele

    2015-11-16

    Competition between males and their sperm over access to females and their eggs has resulted in manifold ways by which males try to secure paternity, ranging from physically guarding the female after mating to reducing her receptivity or her attractiveness to subsequent males by transferring manipulative substances or by mechanically sealing the female reproductive tract with a copulatory plug. Copulations may also result in internal damage of the female genitalia; however, this is not considered as a direct adaptation against sperm competition but as a collateral effect. Here, we present a drastic and direct mechanism for securing paternity: the removal of coupling structures on female genitalia by males. In the orb-weaving spider Larinia jeskovi males remove the scapus, a crucial coupling device on the female external genital region. Reconstruction of the coupling mechanism using micro-CT-scanned mating pairs revealed that several sclerites of the male genitalia interact to break off the scapus. Once it is removed, remating cannot occur due to mechanical coupling difficulties. In the field, male-inflicted genital damage is very prevalent since all female L. jeskovi were found to be mutilated at the end of the mating season. External genital mutilation is an overlooked but widely spread phenomenon since 80 additional spider species were found for which male genital manipulation can be suspected. Interlocking genitalia provide an evolutionary platform for the rapid evolution of this highly effective mechanism to secure paternity, and we suspect that other animal groups with interlocking genital structures might reveal similarly drastic male adaptations. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Untangling taxonomy: a DNA barcode reference library for Canadian spiders.

    Blagoev, Gergin A; deWaard, Jeremy R; Ratnasingham, Sujeevan; deWaard, Stephanie L; Lu, Liuqiong; Robertson, James; Telfer, Angela C; Hebert, Paul D N

    2016-01-01

    Approximately 1460 species of spiders have been reported from Canada, 3% of the global fauna. This study provides a DNA barcode reference library for 1018 of these species based upon the analysis of more than 30,000 specimens. The sequence results show a clear barcode gap in most cases with a mean intraspecific divergence of 0.78% vs. a minimum nearest-neighbour (NN) distance averaging 7.85%. The sequences were assigned to 1359 Barcode index numbers (BINs) with 1344 of these BINs composed of specimens belonging to a single currently recognized species. There was a perfect correspondence between BIN membership and a known species in 795 cases, while another 197 species were assigned to two or more BINs (556 in total). A few other species (26) were involved in BIN merges or in a combination of merges and splits. There was only a weak relationship between the number of specimens analysed for a species and its BIN count. However, three species were clear outliers with their specimens being placed in 11-22 BINs. Although all BIN splits need further study to clarify the taxonomic status of the entities involved, DNA barcodes discriminated 98% of the 1018 species. The present survey conservatively revealed 16 species new to science, 52 species new to Canada and major range extensions for 426 species. However, if most BIN splits detected in this study reflect cryptic taxa, the true species count for Canadian spiders could be 30-50% higher than currently recognized. © 2015 The Authors. Molecular Ecology Resources Published by John Wiley & Sons Ltd.

  20. Multiscale mechanisms of nutritionally induced property variation in spider silks

    Nobbs, Madeleine; Martens, Penny J.; Tso, I-Min; Chuang, Wei-Tsung; Chang, Chung-Kai; Sheu, Hwo-Shuenn

    2018-01-01

    Variability in spider major ampullate (MA) silk properties at different scales has proven difficult to determine and remains an obstacle to the development of synthetic fibers mimicking MA silk performance. A multitude of techniques may be used to measure multiscale aspects of silk properties. Here we fed five species of Araneoid spider solutions that either contained protein or were protein deprived and performed silk tensile tests, small and wide-angle X-ray scattering (SAXS/WAXS), amino acid composition analyses, and silk gene expression analyses, to resolve persistent questions about how nutrient deprivation induces variations in MA silk mechanical properties across scales. Our analyses found that the properties of each spider’s silk varied differently in response to variations in their protein intake. We found changes in the crystalline and non-crystalline nanostructures to play specific roles in inducing the property variations we found. Across treatment MaSp expression patterns differed in each of the five species. We found that in most species MaSp expression and amino acid composition variations did not conform with our predictions based on a traditional MaSp expression model. In general, changes to the silk’s alanine and proline compositions influenced the alignment of the proteins within the silk’s amorphous region, which influenced silk extensibility and toughness. Variations in structural alignment in the crystalline and non-crystalline regions influenced ultimate strength independent of genetic expression. Our study provides the deepest insights thus far into the mechanisms of how MA silk properties vary from gene expression to nanostructure formations to fiber mechanics. Such knowledge is imperative for promoting the production of synthetic silk fibers. PMID:29390013

  1. Traditions in spider monkeys are biased towards the social domain.

    Claire J Santorelli

    Full Text Available Cross-site comparison studies of behavioral variation can provide evidence for traditions in wild species once ecological and genetic factors are excluded as causes for cross-site differences. These studies ensure behavior variants are considered within the context of a species' ecology and evolutionary adaptations. We examined wide-scale geographic variation in the behavior of spider monkeys (Ateles geoffroyi across five long-term field sites in Central America using a well established ethnographic cross-site survey method. Spider monkeys possess a relatively rare social system with a high degree of fission-fusion dynamics, also typical of chimpanzees (Pan troglodytes and humans (Homo sapiens. From the initial 62 behaviors surveyed 65% failed to meet the necessary criteria for traditions. The remaining 22 behaviors showed cross-site variation in occurrence ranging from absent through to customary, representing to our knowledge, the first documented cases of traditions in this taxon and only the second case of multiple traditions in a New World monkey species. Of the 22 behavioral variants recorded across all sites, on average 57% occurred in the social domain, 19% in food-related domains and 24% in other domains. This social bias contrasts with the food-related bias reported in great ape cross-site comparison studies and has implications for the evolution of human culture. No pattern of geographical radiation was found in relation to distance across sites. Our findings promote A. geoffroyi as a model species to investigate traditions with field and captive based experiments and emphasize the importance of the social domain for the study of animal traditions.

  2. Probe-diverse ptychography

    Peterson, I., E-mail: isaac.russellpeterson@rmit.edu.au [ARC Centre of Excellence for Coherent X-ray Science, the University of Melbourne, School of Physics, Victoria 3010 (Australia); Harder, R. [Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439 (United States); Robinson, I.K. [Research Complex at Harwell, Didcot, Oxfordshire OX11 0DE (United Kingdom); London Centre for Nanotechnology, University College London, London WC1H 0AH (United Kingdom)

    2016-12-15

    We propose an extension of ptychography where the target sample is scanned separately through several probes with distinct amplitude and phase profiles and a diffraction image is recorded for each probe and each sample translation. The resulting probe-diverse dataset is used to iteratively retrieve high-resolution images of the sample and all probes simultaneously. The method is shown to yield significant improvement in the reconstructed sample image compared to the image obtained using the standard single-probe ptychographic phase-retrieval scheme.

  3. Gamma irradiation as a quarantine treatment for spider mites (Acarina: tetranychidae) in horticultural products

    Ignatowicz, S.; Banasik-Solgala, K.

    1999-01-01

    The carmine spider mite, Tetranychus cinnabarinus (Boisd.), and the two-spotted spider mite, Tetranychus urticae Koch, are closely related species of tetranychid mites (Acarina, Tetranychidae) that respond to gamma irradiation in a similar way. Eggs of both species exposed to gamma radiation early in embryonic development were considerably more susceptible to irradiation than older eggs. The tolerance of eggs to gamma radiation increased in 3-4-day-old eggs, when eye-spots were formed. Nymphs were more resistant to gamma radiation than eggs and larvae. Deteriorative effects of irradiation treatment were reflected in the immatures by their mortality in subsequent developmental stages. A positive relationship between dosage and the percent egg mortality or the mortality of subsequent stages was usually found when the immature stages were irradiated. The sex ratio of adults developed from irradiated eggs, larvae, and nymphs was affected by the irradiation treatment; the ratio was usually skewed towards males. Irradiation of females resulted in increased mortality, lowered fecundity, reduced egg viability, and sex ratio distortion in their progeny. Two-day-old females of the carmine spider mite and the two-spotted spider mite irradiated with 200 or 300 Gy lived as long as the controls. Mortality occurred after 3 weeks. The number of eggs laid by irradiated females of spider mites was considerably lower than in the control, and it decreased as the absorbed dose increased. The higher the dose of gamma radiation applied to adults of the spider mites (the parental generation, P), the higher the mortality of the F1 mites during their embryonic development. Viability of eggs laid by irradiated females of spider mites mated with irradiated males was significantly reduced. Young females treated with a dose of 0.2 kGy produced 40-50% nonviable eggs, while control mites produced only 6.0-6.6% nonviable eggs. A dose of 0.3 kGy caused high mortality of eggs; 88% and 97% nonviable

  4. Traversing probe system

    Mashburn, D.N.; Stevens, R.H.; Woodall, H.C.

    1977-01-01

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride. 10 claims, 6 figures

  5. Traversing probe system

    Mashburn, Douglas N.; Stevens, Richard H.; Woodall, Harold C.

    1977-01-01

    This invention comprises a rotatable annular probe-positioner which carries at least one radially disposed sensing probe, such as a Pitot tube having a right-angled tip. The positioner can be coaxially and rotatably mounted within a compressor casing or the like and then actuated to orient the sensing probe as required to make measurements at selected stations in the annulus between the positioner and compressor casing. The positioner can be actuated to (a) selectively move the probe along its own axis, (b) adjust the yaw angle of the right-angled probe tip, and (c) revolve the probe about the axis common to the positioner and casing. A cam plate engages a cam-follower portion of the probe and normally rotates with the positioner. The positioner includes a first-motor-driven ring gear which effects slidable movement of the probe by rotating the positioner at a time when an external pneumatic cylinder is actuated to engage the cam plate and hold it stationary. When the pneumatic cylinder is not actuated, this ring gear can be driven to revolve the positioner and thus the probe to a desired circumferential location about the above-mentioned common axis. A second motor-driven ring gear included in the positioner can be driven to rotate the probe about its axis, thus adjusting the yaw angle of the probe tip. The positioner can be used in highly corrosive atmosphere, such as gaseous uranium hexafluoride.

  6. Electrical resistivity probes

    Lee, Ki Ha; Becker, Alex; Faybishenko, Boris A.; Solbau, Ray D.

    2003-10-21

    A miniaturized electrical resistivity (ER) probe based on a known current-voltage (I-V) electrode structure, the Wenner array, is designed for local (point) measurement. A pair of voltage measuring electrodes are positioned between a pair of current carrying electrodes. The electrodes are typically about 1 cm long, separated by 1 cm, so the probe is only about 1 inch long. The electrodes are mounted to a rigid tube with electrical wires in the tube and a sand bag may be placed around the electrodes to protect the electrodes. The probes can be positioned in a borehole or on the surface. The electrodes make contact with the surrounding medium. In a dual mode system, individual probes of a plurality of spaced probes can be used to measure local resistance, i.e. point measurements, but the system can select different probes to make interval measurements between probes and between boreholes.

  7. A comparative analysis of the morphology and evolution of permanent sperm depletion in spiders.

    Peter Michalik

    2011-01-01

    Full Text Available Once thought to be energetically cheap and easy to produce, empirical work has shown that sperm is a costly and limited resource for males. In some spider species, there is behavioral evidence that sperm are permanently depleted after a single mating. This extreme degree of mating investment appears to co-occur with other reproductive strategies common to spiders, e.g. genital mutilation and sexual cannibalism. Here we corroborate that sperm depletion in the golden orb-web spider Nephila clavipes is permanent by uncovering its mechanistic basis using light and electron microscopy. In addition, we use a phylogeny-based statistical analysis to test the evolutionary relationships between permanent sperm depletion (PSD and other reproductive strategies in spiders. Male testes do not produce sperm during adulthood, which is unusual in spiders. Instead, spermatogenesis is nearly synchronous and ends before the maturation molt. Testis size decreases as males approach their maturation molt and reaches its lowest point after sperm is transferred into the male copulatory organs (pedipalps. As a consequence, the amount of sperm available to males for mating is limited to the sperm contained in the pedipalps, and once it is used, males lose their ability to fertilize eggs. Our data suggest that PSD has evolved independently at least three times within web-building spiders and is significantly correlated with the evolution of other mating strategies that limit males to monogamy, including genital mutilation and sexual cannibalism. We conclude that PSD may be an energy-saving adaptation in species where males are limited to monogamy. This could be particularly important in web-building spiders where extreme sexual size dimorphism results in large, sedentary females and small, searching males who rarely feed as adults and are vulnerable to starvation. Future work will explore possible energetic benefits and the evolutionary lability of PSD relative to other

  8. Management intensity and vegetation complexity affect web-building spiders and their prey.

    Diehl, Eva; Mader, Viktoria L; Wolters, Volkmar; Birkhofer, Klaus

    2013-10-01

    Agricultural management and vegetation complexity affect arthropod diversity and may alter trophic interactions between predators and their prey. Web-building spiders are abundant generalist predators and important natural enemies of pests. We analyzed how management intensity (tillage, cutting of the vegetation, grazing by cattle, and synthetic and organic inputs) and vegetation complexity (plant species richness, vegetation height, coverage, and density) affect rarefied richness and composition of web-building spiders and their prey with respect to prey availability and aphid predation in 12 habitats, ranging from an uncut fallow to a conventionally managed maize field. Spiders and prey from webs were collected manually and the potential prey were quantified using sticky traps. The species richness of web-building spiders and the order richness of prey increased with plant diversity and vegetation coverage. Prey order richness was lower at tilled compared to no-till sites. Hemipterans (primarily aphids) were overrepresented, while dipterans, hymenopterans, and thysanopterans were underrepresented in webs compared to sticky traps. The per spider capture efficiency for aphids was higher at tilled than at no-till sites and decreased with vegetation complexity. After accounting for local densities, 1.8 times more aphids were captured at uncut compared to cut sites. Our results emphasize the functional role of web-building spiders in aphid predation, but suggest negative effects of cutting or harvesting. We conclude that reduced management intensity and increased vegetation complexity help to conserve local invertebrate diversity, and that web-building spiders at sites under low management intensity (e.g., semi-natural habitats) contribute to aphid suppression at the landscape scale.

  9. Three-dimensional printing spiders: back-and-forth glue application yields silk anchorages with high pull-off resistance under varying loading situations.

    Wolff, Jonas O; Herberstein, Marie E

    2017-02-01

    The anchorage of structures is a crucial element of construction, both for humans and animals. Spiders use adhesive plaques to attach silk threads to substrates. Both biological and artificial adhesive structures usually have an optimal loading angle, and are prone to varying loading situations. Silk anchorages, however, must cope with loading in highly variable directions. Here we show that the detachment forces of thread anchorages of orb-web spiders are highly robust against pulling in different directions. This is gained by a two-step back-and-forth spinning pattern during the rapid production of the adhesive plaque, which shifts the thread insertion point towards the plaque centre and forms a flexible tree root-like network of branching fibres around the loading point. Using a morphometric approach and a tape-and-thread model we show that neither area, nor width of the plaque, but the shift of the loading point towards the plaque centre has the highest effect on pull-off resistance. This is explained by a circular propagation of the delamination crack with a low peeling angle. We further show that silken attachment discs are highly directional and adjusted to provide maximal performance in the upstream dragline. These results show that the way the glue is applied, crucially enhances the toughness of the anchorage without the need of additional material intake. This work is a starting point to study the evolution of tough and universal thread anchorages among spiders, and to develop bioinspired 'instant' anchorages of thread- and cable-like structures to a broad bandwidth of substrates. © 2017 The Author(s).

  10. Cognitive bias in spider fear and control children: Assessment of emotional interference by a card format and a single-trial format of the Stroop task

    Kindt, M.; Bierman, D.; Brosschot, J.F.

    1997-01-01

    Aimed to clarify whether nonclinical fear of spiders in children is related to a distorted cognitive processing of fear-related information. It was hypothesized that if a processing bias for threatening information is inherent to spider fear, a bias for spider-related information would be found in

  11. Formation of primary sperm conjugates in a haplogyne spider (Caponiidae, Araneae) with remarks on the evolution of sperm conjugation in spiders.

    Lipke, Elisabeth; Michalik, Peter

    2012-11-01

    Sperm conjugation, where two or more sperm are physically united, is a rare but widespread pheno-menon across the animal kingdom. One group well known for its different types of sperm conjugation are spiders. Particularly, haplogyne spiders show a high diversity of sperm traits. Besides individual cleistospermia, primary (synspermia) and secondary (coenospermia, "spermatophore") sperm conjugation occurs. However, the evolution of sperm conjugates and sperm is not understood in this group. Here, we look at how sperm are transferred in Caponiidae (Haplogynae) in pursuit of additional information about the evolution of sperm transfer forms in spiders. Additionally, we investigated the male reproductive system and spermatozoa using light- and transmission electron-microscopy and provide a 3D reconstruction of individual as of well as conjugated spermatozoa. Mature spermatozoa are characterized by an extremely elongated, helical nucleus resulting in the longest spider sperm known to date. At the end of spermiogenesis, synspermia are formed by complete fusion of four spermatids. Thus, synspermia might have evolved early within ecribellate Haplogynae. The fused sperm cells are surrounded by a prominent vesicular area. The function of the vesicular area remains still unknown but might be correlated with the capacitation process inside the female. Further phylogenetic and functional implications of the spermatozoa and sperm conjugation are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

  12. Identifying members of the domain Archaea with rRNA-targeted oligonucleotide probes.

    Burggraf, S; Mayer, T; Amann, R; Schadhauser, S; Woese, C R; Stetter, K O

    1994-01-01

    Two 16S rRNA-targeted oligonucleotide probes were designed for the archaeal kingdoms Euryachaeota and Crenarchaeota. Probe specificities were evaluated by nonradioactive dot blot hybridization against selected reference organisms. The successful application of fluorescent-probe derivatives for whole-cell hybridization required organism-specific optimizations of fixation and hybridization conditions to assure probe penetration and morphological integrity of the cells. The probes allowed prelim...

  13. Tomato whole genome transcriptional response to Tetranychus urticae identifies divergence of spider mite-induced responses between tomato and Arabidopsis

    Martel, C.; Zhurov, V.; Navarro, M.; Martinez, M.; Cazaux, M.; Auger, P.; Migeon, A.; Santamaria, M.E.; Wybouw, N.; Diaz, I.; Van Leeuwen, T.; Navajas, M.; Grbic, M.; Grbic, V.

    2015-01-01

    The two-spotted spider mite Tetranychus urticae is one of the most significant mite pests in agriculture, feeding on more than 1,100 plant hosts, including model plants Arabidopsis thaliana and tomato, Solanum lycopersicum. Here, we describe timecourse tomato transcriptional responses to spider mite

  14. Habitat preferences, diet, feeding strategy and social organization of the black spider monkey (Ateles paniscus paniscus Linnaeus 1758) in Surinam

    Roosmalen, van M.G.M.

    1980-01-01

    This study describes habitat choice of the Surinam black spider monkey ( Atelespaniscuspaniscus ) and clarifies complex temporal and spatial effects of food sources on the behaviour of a group of spider monkeys in a 350 ha study area in

  15. Implicit and Explicit Attitudes Toward Spiders : Sensitivity to Treatment and Predictive Value for Generalization of Treatment Effects

    Huijding, Jorg; de Jong, Peter J.

    This study tested whether high spider fearful individuals' implicit and explicit attitudes toward spiders are sensitive to exposure treatment, and whether post-treatment implicit and/or explicit attitudes are related to the generalization of treatment effects. Self-reported explicit and implicit

  16. Voracious male spiders that kill adult females of their own species (genera Walckenaeria, Diplostyla, Neriene, Meta, Araneae)

    Heuts, B.; Brunt, T.

    2008-01-01

    In contrast to the popular belief that adult female spiders often kill and eat their adult male partners in the context of copulation, we present a few instances of adult male spiders killing and eating adult females of their own species in the laboratory. However, in line with the popular belief,

  17. Cryptic color change in a crab spider (Misumena vatia): identification and quantification of precursors and ommochrome pigments by HPLC.

    Riou, Mickaël; Christidès, Jean-Philippe

    2010-04-01

    Mimicry is used widely by arthropods to survive in a hostile environment. Often mimicry is associated with the production of chemical compounds such as pigments. In crab spiders, the change of color is based on a complex physiological process that still is not understood. The aim of this study was to identify and quantify the ommochrome pigments and precursors responsible for the color change in the mimetic crab spider Misumena vatia (Thomisidae). A modified high performance reverse phase ion-pair chromatography technique enabled us to separate and quantify the ommochrome pigments, their precursors, and related metabolites in individual spiders. Compounds such as tryptophan, kynurenine, and kynurenic acid occurred only or mainly in white crab spiders. In contrast, compounds such as 3-hydroxy-kynurenine, xanthommatin, and ommatin D occurred only or mainly in yellow crab spiders. Factor analysis ranked the different color forms in accordance with their metabolites. The biochemical results enabled us to associate the different phases of formation of pigment granules with specific metabolites. Yellow crab spiders contain many unknown ommochrome-like compounds not present in white crab spiders. We also found large quantities of decarboxylated xanthommatin, whose role as precursor of new pathways in ommochrome synthesis needs to be assessed. The catabolism of ommochromes, a process occurring when spiders revert from yellow to white, warrants further study.

  18. Effects of hunger level and nutrient balance on survival and acetylcholinesterase activity of dimethoate exposed wolf spiders

    Pedersen, Lars-Flemming; Dall, Lars G.; Sorensen, Bo C.

    2002-01-01

    The influence of two nutritional factors (food quantity and quality) on the responses of a wolf spider, Pardosa prativaga (L.K.), to a high dose of the insecticide dimethoate, was investigated in a fully factorial experimental design. Spider groups with different (good and bad) nutrient balance w...

  19. Hg-contaminated terrestrial spiders pose a potential risk to songbirds at Caddo Lake (Texas/Louisiana, USA).

    Gann, Gretchen L; Powell, Cleveland H; Chumchal, Matthew M; Drenner, Ray W

    2015-02-01

    Methylmercury (MeHg) is an environmental contaminant that can have adverse effects on wildlife. Because MeHg is produced by bacteria in aquatic ecosystems, studies of MeHg contamination of food webs historically have focused on aquatic organisms. However, recent studies have shown that terrestrial organisms such as songbirds can be contaminated with MeHg by feeding on MeHg-contaminated spiders. In the present study, the authors examined the risk that MeHg-contaminated terrestrial long-jawed orb weaver spiders (Tetragnatha sp.) pose to songbirds at Caddo Lake (Texas/Louisiana, USA). Methylmercury concentrations in spiders were significantly different in river, wetland, and open-water habitats. The authors calculated spider-based wildlife values (the minimum spider MeHg concentrations causing physiologically significant doses in consumers) to assess exposure risks for arachnivorous birds. Methylmercury concentrations in spiders exceeded wildlife values for Carolina chickadee (Poecile carolinensis) nestlings, with the highest risk in the river habitat. The present study indicates that MeHg concentrations in terrestrial spiders vary with habitat and can pose a threat to small-bodied nestling birds that consume large amounts of spiders at Caddo Lake. This MeHg threat to songbirds may not be unique to Caddo Lake and may extend throughout the southeastern United States. © 2014 SETAC.

  20. Temporal patterns in the abundance and species composition of spiders on host plants of the invasive moth Epiphyas postvittana

    Generalist predators such as spiders may help mitigate the spread and impact of exotic herbivores. The lack of prey specificity and long generation times of spiders may allow them to persist when pests are scarce, and to limit the growth of pest populations before they reach damaging levels. We exam...