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Sample records for field frog deformities

  1. Field evidence for linking Altosid applications with increased amphibian deformities in southern leopard frogs [abstract

    USGS Publications Warehouse

    Sparling, D.W.

    1998-01-01

    During the summer of 1997 we repeatedly sprayed Altosid, a formulation of 4% methoprene used for mosquito control, on six constructed macrocosms. Six additional macrocosms were sprayed with Abate4E, containing the organophosphate pesticide temephos, and six were sprayed with water (controls). The wetlands were created on an impermeable foundation for research purposes and averaged 215 m2 in area and 0.5 m deep. Application rates and frequency of Abate4E and Altosid followed label directions and mimicked procedures for mosquito control in National Wildlife Refuges. In early September juvenile frogs and metamorphing tadpoles were collected with dip nets from each pond and examined for deformities. In all, 91 juveniles and metamorph southern leopard frogs (Rana utricularia) were collected from Altosid sprayed wetlands with 14 (15%) demonstrating deformities. Seventyseven juveniles and metamorphs were collected from control wetlands with three (4%) showing deformities. Only six juveniles and metamorphs were collected from Abate4E wetlands and none showed deformities. Deformities included missing or deformed hind limbs (9 of 10 involving only the right hind limb), missing eyes, and abnormal color. The differences in rate of deformities was dependent on treatment (X2=6.44, p< 0.02). The number of leopard frogs caught per unit effort (tadpoles and juveniles) differed among treatments (p=0.032) with Abate4E wetlands producing fewer individuals per capture effort than either Altosid or control wetlands.

  2. Induction of mortality and malformation in Xenopus laevis embryos by water sources associated with field frog deformities.

    PubMed Central

    Burkhart, J G; Helgen, J C; Fort, D J; Gallagher, K; Bowers, D; Propst, T L; Gernes, M; Magner, J; Shelby, M D; Lucier, G

    1998-01-01

    Water samples from several ponds in Minnesota were evaluated for their capacity to induce malformations in embryos of Xenopus laevis. The FETAX assay was used to assess the occurrence of malformations following a 96-hr period of exposure to water samples. These studies were conducted following reports of high incidences of malformation in natural populations of frogs in Minnesota wetlands. The purpose of these studies was to determine if a biologically active agent(s) was present in the waters and could be detected using the FETAX assay. Water samples from ponds with high incidences of frog malformations (affected sites), along with water samples from ponds with unaffected frog populations (reference sites), were studied. Initial experiments clearly showed that water from affected sites induced mortality and malformation in Xenopus embryos, while water from reference sites had little or no effect. Induction of malformation was dose dependent and highly reproducible, both with stored samples and with samples taken at different times throughout the summer. The biological activity of the samples was reduced or eliminated when samples were passed through activated carbon. Limited evidence from these samples indicates that the causal factor(s) is not an infectious organism nor are ion concentrations or metals responsible for the effects observed. Results do indicate that the water matrix has a significant effect on the severity of toxicity. Based on the FETAX results and the occurrence of frog malformations observed in the field, these studies suggest that water in the affected sites contains one or more unknown agents that induce developmental abnormalities in Xenopus. These same factors may contribute to the increased incidence of malformation in native species. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:9831545

  3. Faint Infrared-Excess Field Galaxies: FROGs

    NASA Astrophysics Data System (ADS)

    Moustakas, L. A.; Davis, M.; Zepf, S. E.; Bunker, A. J.

    Deep near-infrared and optical imaging surveys in the field reveal a curious population of galaxies that are infrared-bright (I-K>4), yet with relatively blue optical colors (V-I<2). Their surface density, several per square arcminute at K>20, is high enough that if placed at z>1 as our models suggest, their space densities are about one-tenth of phi-*. The colors of these ``faint red outlier galaxies'' (fROGs) may derive from exceedingly old underlying stellar populations, a dust-embedded starburst or AGN, or a combination thereof. Determining the nature of these fROGs, and their relation with the I-K>6 ``extremely red objects,'' has implications for our understanding of the processes that give rise to infrared-excess galaxies in general. We report on an ongoing study of several targets with HST & Keck imaging and Keck/LRIS multislit spectroscopy.

  4. Marsh frogs, Pelophylax ridibundus, determine migratory direction by magnetic field.

    PubMed

    Shakhparonov, Vladimir V; Ogurtsov, Sergei V

    2017-01-01

    Orientation by magnetic cues appears to be adaptive during animal migrations. Whereas the magnetic orientation in birds, mammals, and urodele amphibians is being investigated intensively, the data about anurans are still scarce. This study tests whether marsh frogs could determine migratory direction between the breeding pond and the wintering site by magnetic cues in the laboratory. Adult frogs (N = 32) were individually tested in the T-maze 127 cm long inside the three-axis Helmholtz coil system (diameter 3 m). The arms of the maze were positioned parallel to the natural migratory route of this population when measured in accordance with magnetic field. The frogs were tested under two-motivational conditions mediated by temperature/light regime: the breeding migratory state and the wintering state. The frogs' choice in a T-maze was evident only when analyzed in accordance with the direction of the magnetic field: they moved along the migratory route to the breeding pond and followed the reversion of the horizontal component of the magnetic field. This preference has been detected in both sexes only in the breeding migratory state. This suggests that adult ranid frogs can obtain directional information from the Earth's magnetic field as was shown earlier in urodeles and anuran larvae.

  5. Visual field topography and binocular responses in frog's nucleus isthmi.

    PubMed

    Wang, S R; Yan, K; Wang, Y T

    1981-09-01

    Visual responses of 125 units have been extracellularly recorded with glass micropipettes from the left nucleus isthmi in the frog Rana nigromaculata, and 101 electrode tip positions marked with cobalt staining to reconstruct a visual field map in the nucleus. 80% of the units recorded show ON-OFF responses to a stationary spot of light and many are directionally selective in response to black or white targets moving through their receptive fields. All the cobalt-marked spots are within the nucleus, indicating that the nucleus isthmus proper is a restricted part of the frog visual system. There is a visual field map in the nucleus. The entire contralateral hemifield and the nasal 40 degrees of the ipsilateral hemifield project on the nucleus topographically. A cell-free band inside the nucleus is a boundary line separating the contralateral hemifield from the ipsilateral one. Dorsal to it is the contralateral field representation. The upper visual field projects on the rostral half of the nucleus and the central and medio-ventral portion of its caudal half. The lower field is represented on the dorsal and lateral part of the caudal half. Fifteen binocular units have been found from the nucleus, 13 of which are dominantly activated by the contralateral eye, the other two are almost equally excited by either eye. These binocular units are mainly situated in the medulla of the rostral half of the nucleus isthmus.

  6. The embryonic development of frogs under strong DC magnetic fields

    SciTech Connect

    Ueno, S.; Harada, K.; Shiodawa, K.

    1984-09-01

    Possible influence of d.c. magnetic fields in the early embryonic development of frogs was studied. Embryos of African clawed toads, Xenopus laevis, were exposed to 1.0 T magnetic fields with different gradients of a range from 10 T/m to 10/sup 3/ T/m either during cleavage to neurula stage, blastula to neurula stage, or neurula to tail bud stage. The developmental processes of embryos during and after magnetic field exposures were followed to examine a possibility of teratogenic effects. The results suggest that the magnetic field exerts no harmful or modifying effects on the important morphogenetic movements such as gastrulation and neurulation. However, it was observed that embryos which were exposed to the gradient magnetic fields during cleavage to neurula stage occasionally developed into tadpoles with reduced pigmentation or some axial anomalies such as the formation of curled tail. Tadpoles with edema or microcephaly were also observed. Compared with the control, the rate of malformation was higher by about 35 %. The influence of oxygen concentration in Ringer's solution on the embryonic development was also studied, and toxicity of oxygen with high concentration is discussed.

  7. Deformation quantization of fermi fields

    SciTech Connect

    Galaviz, I. Garcia-Compean, H. Przanowski, M. Turrubiates, F.J.

    2008-04-15

    Deformation quantization for any Grassmann scalar free field is described via the Weyl-Wigner-Moyal formalism. The Stratonovich-Weyl quantizer, the Moyal *-product and the Wigner functional are obtained by extending the formalism proposed recently in [I. Galaviz, H. Garcia-Compean, M. Przanowski, F.J. Turrubiates, Weyl-Wigner-Moyal Formalism for Fermi Classical Systems, arXiv:hep-th/0612245] to the fermionic systems of infinite number of degrees of freedom. In particular, this formalism is applied to quantize the Dirac free field. It is observed that the use of suitable oscillator variables facilitates considerably the procedure. The Stratonovich-Weyl quantizer, the Moyal *-product, the Wigner functional, the normal ordering operator, and finally, the Dirac propagator have been found with the use of these variables.

  8. Surveys for presence of Oregon spotted frog (Rana pretiosa): background information and field methods

    USGS Publications Warehouse

    Pearl, Christopher A.; Clayton, David; Turner, Lauri

    2010-01-01

    The Oregon spotted frog (Rana pretiosa) is the most aquatic of the native frogs in the Pacific Northwest. The common name derives from the pattern of black, ragged-edged spots set against a brown or red ground color on the dorsum of adult frogs. Oregon spotted frogs are generally associated with wetland complexes that have several aquatic habitat types and sizeable coverage of emergent vegetation. Like other ranid frogs native to the Northwest, Oregon spotted frogs breed in spring, larvae transform in summer of their breeding year, and adults tend to be relatively short lived (3-5 yrs). Each life stage (egg, tadpole, juvenile and adult) has characteristics that present challenges for detection. Breeding can be explosive and completed within 1-2 weeks. Egg masses are laid in aggregations, often in a few locations in large areas of potential habitat. Egg masses can develop, hatch, and disintegrate in <2 weeks during warm weather. Tadpoles can be difficult to identify, have low survival, and spend most of their 3-4 months hidden in vegetation or flocculant substrates. Juveniles and adults are often difficult to capture and can spend summers away from breeding areas. Moreover, a substantial portion of extant populations are of limited size (<100 breeding adults), and field densities of all life stages are often low. An understanding of the biology of the species and use of multiple visits are thus important for assessing presence of Oregon spotted frogs. This report is meant to be a resource for USDA Region 6 Forest Service (FS) and OR/WA Bureau of Land Management (BLM) personnel tasked with surveying for the presence of Oregon spotted frogs. Our objective was to summarize information to improve the efficiency of field surveys and increase chances of detection if frogs are present. We include overviews of historical and extant ranges of Oregon spotted frog. We briefly summarize what is known of Oregon spotted frog habitat associations and review aspects of behavior and

  9. Pathological Study of Blood Parasites in Rice Field Frogs, Hoplobatrachus rugulosus (Wiegmann, 1834).

    PubMed

    Sailasuta, Achariya; Satetasit, Jetjun; Chutmongkonkul, Malinee

    2011-01-01

    One hundred and forty adult rice field frogs, Hoplobatrachus rugulosus (Wiegmann, 1834), were collected in Srakaew province, Thailand. For blood parasite examination, thin blood smears were made and routinely stained with Giemsa. The results showed that 70% of the frogs (98/140) were infected with 5 species of blood parasites, including a Trypanosoma rotatorium-like organism, Trypanosoma chattoni, Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima. Pathological examination of the liver, lung, spleen, and kidney of the frogs that were apparently infected with one of these blood parasites were collected and processed by routine histology and subsequently stained with haematoxylin and eosin. Histopathological findings associated with the Trypanosoma rotatorium-like organism and Trypanosoma chattoni-infected frogs showed no pathological lesions. Hepatozoon sp. a and Hepatozoon sp. b-infected frogs developed inflammatory lesions predominantly in the liver, demonstrating granuloma-like lesions with Hepatozoon sp. meronts at the centre. Tissue sections of Lankesterella minima-infected frogs also showed lesions. Liver and spleen showed inflammatory lesions with an accumulation of melanomacrophage centres (MMCs) surrounding the meronts and merozoites. It is suggested that Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima-infections are capable of producing inflammatory lesions in the visceral organs of rice field frogs, and the severity of lesions is tentatively related to levels of parasitemia.

  10. Pathological Study of Blood Parasites in Rice Field Frogs, Hoplobatrachus rugulosus (Wiegmann, 1834)

    PubMed Central

    Sailasuta, Achariya; Satetasit, Jetjun; Chutmongkonkul, Malinee

    2011-01-01

    One hundred and forty adult rice field frogs, Hoplobatrachus rugulosus (Wiegmann, 1834), were collected in Srakaew province, Thailand. For blood parasite examination, thin blood smears were made and routinely stained with Giemsa. The results showed that 70% of the frogs (98/140) were infected with 5 species of blood parasites, including a Trypanosoma rotatorium-like organism, Trypanosoma chattoni, Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima. Pathological examination of the liver, lung, spleen, and kidney of the frogs that were apparently infected with one of these blood parasites were collected and processed by routine histology and subsequently stained with haematoxylin and eosin. Histopathological findings associated with the Trypanosoma rotatorium-like organism and Trypanosoma chattoni-infected frogs showed no pathological lesions. Hepatozoon sp. a and Hepatozoon sp. b-infected frogs developed inflammatory lesions predominantly in the liver, demonstrating granuloma-like lesions with Hepatozoon sp. meronts at the centre. Tissue sections of Lankesterella minima-infected frogs also showed lesions. Liver and spleen showed inflammatory lesions with an accumulation of melanomacrophage centres (MMCs) surrounding the meronts and merozoites. It is suggested that Hepatozoon sp. a, Hepatozoon sp. b, and Lankesterella minima-infections are capable of producing inflammatory lesions in the visceral organs of rice field frogs, and the severity of lesions is tentatively related to levels of parasitemia. PMID:21918731

  11. Field guide to malformations of frogs and toads, with radiographic interpretations

    USGS Publications Warehouse

    Meteyer, Carol U.

    2000-01-01

    In 1995, students found numerous malformed frogs on a field trip to a Minnesota pond. Since that time, reports of malformed frogs have increased dramatically. Malformed frogs have now been reported in 44 states in 38 species of frogs, and 19 species of toads. Estimates as high as 60% of the newly metamorphosed frog populations have had malformations at some ponds (NARCAM, ’99). The wide geographic distribution of malformed frogs and the variety of malformations are a concern to resource managers, research scientists and public health officials. The potential for malformations to serve as a signal of ecosystem disruption, and the affect this potential disruption might have on other organisms that share those ecosystems, has not been resolved. Malformations represent an error that occurred early in development. The event that caused the developmental error is temporally distant from the malformation we see in the fully developed animal. Knowledge of normal developmental principles is necessary to design thoughtful investigations that will define the events involved in abnormal development in wild frog populations.

  12. Noncommutative scalar fields from symplectic deformation

    SciTech Connect

    Daoud, M.; Hamama, A.

    2008-02-15

    This paper is concerned with the quantum theory of noncommutative scalar fields in two dimensional space-time. It is shown that the noncommutativity originates from the the deformation of symplectic structures. The quantization is performed and the modes expansions of the fields, in the presence of an electromagnetic background, are derived. The Hamiltonian of the theory is given and the degeneracies lifting, induced by the deformation, is also discussed.

  13. Replication in field biology: the case of the frog-eating bat.

    PubMed

    Ryan, Michael J

    2011-12-02

    Studies conducted in the field offer unique opportunities to observe nature, but achieving true replication under natural conditions is challenging. As demonstrated by the discovery of frog eating by a charismatic bat, biology conducted in the field generally follows an interesting progression that includes discovery, demonstration, experimentation, and verification.

  14. Spatio-Temporal Dynamics in Collective Frog Choruses Examined by Mathematical Modeling and Field Observations

    NASA Astrophysics Data System (ADS)

    Aihara, Ikkyu; Mizumoto, Takeshi; Otsuka, Takuma; Awano, Hiromitsu; Nagira, Kohei; Okuno, Hiroshi G.; Aihara, Kazuyuki

    2014-01-01

    This paper reports theoretical and experimental studies on spatio-temporal dynamics in the choruses of male Japanese tree frogs. First, we theoretically model their calling times and positions as a system of coupled mobile oscillators. Numerical simulation of the model as well as calculation of the order parameters show that the spatio-temporal dynamics exhibits bistability between two-cluster antisynchronization and wavy antisynchronization, by assuming that the frogs are attracted to the edge of a simple circular breeding site. Second, we change the shape of the breeding site from the circle to rectangles including a straight line, and evaluate the stability of two-cluster and wavy antisynchronization. Numerical simulation shows that two-cluster antisynchronization is more frequently observed than wavy antisynchronization. Finally, we recorded frog choruses at an actual paddy field using our sound-imaging method. Analysis of the video demonstrated a consistent result with the aforementioned simulation: namely, two-cluster antisynchronization was more frequently realized.

  15. Deformation field heterogeneity in punch indentation

    PubMed Central

    Murthy, Tejas G.; Saldana, Christopher; Hudspeth, Matthew; M'Saoubi, Rachid

    2014-01-01

    Plastic heterogeneity in indentation is fundamental for understanding mechanics of hardness testing and impression-based deformation processing methods. The heterogeneous deformation underlying plane-strain indentation was investigated in plastic loading of copper by a flat punch. Deformation parameters were measured, in situ, by tracking the motion of asperities in high-speed optical imaging. These measurements were coupled with multi-scale analyses of strength, microstructure and crystallographic texture in the vicinity of the indentation. Self-consistency is demonstrated in description of the deformation field using the in situ mechanics-based measurements and post-mortem materials characterization. Salient features of the punch indentation process elucidated include, among others, the presence of a dead-metal zone underneath the indenter, regions of intense strain rate (e.g. slip lines) and extent of the plastic flow field. Perhaps more intriguing are the transitions between shear-type and compression-type deformation modes over the indentation region that were quantified by the high-resolution crystallographic texture measurements. The evolution of the field concomitant to the progress of indentation is discussed and primary differences between the mechanics of indentation for a rigid perfectly plastic material and a strain-hardening material are described. PMID:24910521

  16. Deformation study of Kamojang geothermal field

    NASA Astrophysics Data System (ADS)

    Ramdhani, B. D.; Meilano, I.; Sarsito, D. A.

    2017-07-01

    GPS has proven to be an indispensable tool in the effort to understand crust deformation before, during, and after the big earthquake events through data analysis and numerical simulation. The development of GPS technology has been able to prove as a method for the detection of geothermal activity that related to deformation. Furthermore, the correlation of deformation and geothermal activity are related to the analysis of potential hazards in the geothermal field itself. But unfortunately, only few GPS observations established to see the relationship of tectonic and geothermal activity around geothermal energy area in Indonesia. This research will observe the interaction between deformation and geothermal sources around the geothermal field Kamojang using geodetic GPS. There are 4 campaign observed points displacement direction to north-east, and 2 others heading to south-east. The displacement of the observed points may have not able proven cause by deformation of geothermal activity due to duration of observation. Since our research considered as pioneer for such investigation in Indonesia, we expect our methodology and our findings could become a starter for other geothermal field cases in Indonesia.

  17. Effect of magnetic fields on green color formation in frog skin

    NASA Astrophysics Data System (ADS)

    Kashiwagi, H.; Kashiwagi, A.; Iwasaka, M.

    2017-05-01

    The present work is focused on a dynamic and efficient optical control system that is made possible by investigation of the body surfaces of various animals. Specifically, we expect Japanese tree frog (Hyla japonica) skin to provide a model for a flexible display device actuator mechanism. Tree frogs change body color from their original green to other colors in response to background colors. The color formation is controlled not only by chromatophores, but also by guanine microcrystals in iridophores. We collected sample microcrystals from the frog's dorsal skin and made a model display sheet using the green skin layers. The transparent chamber that contained the crystal suspension was layered to enhance light reflection. Sheet color was observed while the angle of light incidence was varied, with and without magnetic field exposure at 0.3 T. A slight increase in red and green intensity was detected. Additionally, reflected intensity increased with increasing angle of incidence. These results indicate that the guanine crystal platelets in frog skin can efficiently switch the reflected light direction under application of a magnetic field. This in turn suggests that a several-micron-sized microcrystal of this type is a candidate material for development of flexible optical chips for ambient light control.

  18. Electric field induced deformation of sessile drops

    NASA Astrophysics Data System (ADS)

    Corson, Lindsey; Tsakonas, Costas; Duffy, Brian; Mottram, Nigel; Brown, Carl; Wilson, Stephen

    2014-11-01

    The ability to control the shape of a drop with the application of an electric field has been exploited for many technological applications including measuring surface tension, producing an optical display device, and optimising the optical properties of microlenses. In this work we consider, both theoretically and experimentally, the deformation of pinned sessile drops with contact angles close to either 0° or 90° resting on the lower substrate inside a parallel plate capacitor due to an A.C. electric field. Using both asymptotic and numerical approaches we obtain predictive equations for the static and dynamic drop shape deformations as functions of the key experimental parameters (drop size, capacitor plate separation, electric field magnitude and contact angle). The asymptotic results agree well with the experimental results for a range of liquids. We gratefully acknowledge the financial support of EPSRC via research Grants EP/J009865 and EP/J009873.

  19. Gauge Field Localization on Deformed Branes

    NASA Astrophysics Data System (ADS)

    Tofighi, A.; Moazzen, M.; Farokhtabar, A.

    2016-02-01

    In this paper, we utilise the Chumbes-Holf da Silva-Hott (CHH) mechanism to investigate the issue of gauge field localization on a deformed brane constructed with one scalar field, which can be coupled to gravity minimally or non-minimally. The study of deformed defects is important because they contain internal structures which may have implications in braneworld models. With the CHH mechanism, we find that the massless zero mode of gauge field, in the case of minimal or non-minimal coupling is localized on the brane. Moreover, in the case of non-minimal coupling, it is shown that, when the non-minimal coupling constant is larger than its critical value, then the zero mode is localized on each sub brane.

  20. [Cardiac electric field at the period of depolarization and repolarization of the frog heart ventricle].

    PubMed

    Vaĭkshnoraĭte, M A; Belogolova, A S; Vitiazev, V A; Azarov, Ia E; Shmakov, D N

    2008-01-01

    Multichannel mapping of electrical field on heart ventricle epicardium and the body surface in frogs Rana esculenta and Rana temporaria was performed at periods of the ventricular myocardium depolarization and repolarization. The zone of the epicardium early depolarization is located on epicardium of the ventricle base posterior wall, while the late depolarization zone--on its apex and on the base anterior wall. The total vector of sequence of the ventricle epicardium depolarization is directed from the base to the apex. The zone of the early repolarization is located in the apical area, while that of the late one--in the area of the base. On the frog body surface the cardioelectric field with the cranial zone of negative and the caudal zone of positive potentials is formed before the appearance of the QRS complex on ECG. At the period of the heart ventricle repolarization the zone of the cardioelectric field negative potentials is located in the cranial, while that of the positive ones--in the body surface caudal parts. The cardioelectric field on the frog body surface at the periods of depolarization and repolarization of the ventricle myocardium reflects adequately the projection of sequence of involvement with excitation and of distribution of potentials on epicardium.

  1. Effective field theory for deformed atomic nuclei

    SciTech Connect

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2016-04-13

    In this paper, we present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. Finally, for rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  2. Effective field theory for deformed atomic nuclei

    SciTech Connect

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2016-04-13

    In this paper, we present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. Finally, for rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  3. Effective field theory for deformed atomic nuclei

    NASA Astrophysics Data System (ADS)

    Papenbrock, T.; Weidenmüller, H. A.

    2016-05-01

    We present an effective field theory (EFT) for a model-independent description of deformed atomic nuclei. In leading order this approach recovers the well-known results from the collective model by Bohr and Mottelson. When higher-order corrections are computed, the EFT accounts for finer details such as the variation of the moment of inertia with the band head and the small magnitudes of interband E2 transitions. For rotational bands with a finite spin of the band head, the EFT is equivalent to the theory of a charged particle on the sphere subject to a magnetic monopole field.

  4. Spatio-Temporal Dynamics in Collective Frog Choruses Examined by Mathematical Modeling and Field Observations

    PubMed Central

    Aihara, Ikkyu; Mizumoto, Takeshi; Otsuka, Takuma; Awano, Hiromitsu; Nagira, Kohei; Okuno, Hiroshi G.; Aihara, Kazuyuki

    2014-01-01

    This paper reports theoretical and experimental studies on spatio-temporal dynamics in the choruses of male Japanese tree frogs. First, we theoretically model their calling times and positions as a system of coupled mobile oscillators. Numerical simulation of the model as well as calculation of the order parameters show that the spatio-temporal dynamics exhibits bistability between two-cluster antisynchronization and wavy antisynchronization, by assuming that the frogs are attracted to the edge of a simple circular breeding site. Second, we change the shape of the breeding site from the circle to rectangles including a straight line, and evaluate the stability of two-cluster and wavy antisynchronization. Numerical simulation shows that two-cluster antisynchronization is more frequently observed than wavy antisynchronization. Finally, we recorded frog choruses at an actual paddy field using our sound-imaging method. Analysis of the video demonstrated a consistent result with the aforementioned simulation: namely, two-cluster antisynchronization was more frequently realized. PMID:24463569

  5. Inflation and deformation of conformal field theory

    SciTech Connect

    Garriga, Jaume; Urakawa, Yuko E-mail: yurakawa@ffn.ub.es

    2013-07-01

    It has recently been suggested that a strongly coupled phase of inflation may be described holographically in terms of a weakly coupled quantum field theory (QFT). Here, we explore the possibility that the wave function of an inflationary universe may be given by the partition function of a boundary QFT. We consider the case when the field theory is a small deformation of a conformal field theory (CFT), by the addition of a relevant operator O, and calculate the primordial spectrum predicted in the corresponding holographic inflation scenario. Using the Ward-Takahashi identity associated with Weyl rescalings, we derive a simple relation between correlators of the curvature perturbation ζ and correlators of the deformation operator O at the boundary. This is done without specifying the bulk theory of gravitation, so that the result would also apply to cases where the bulk dynamics is strongly coupled. We comment on the validity of the Suyama-Yamaguchi inequality, relating the bi-spectrum and tri-spectrum of the curvature perturbation.

  6. Comparison of magnetic field and electric potential produced by frog heart muscle

    NASA Astrophysics Data System (ADS)

    Burstein, Deborah; Cohen, David

    1985-04-01

    A comparison is made here between the magnetic field and electric potential produced by a thin strip of frog heart muscle. An experimental test is made of the theory which states that the wave front of a single fiber (or parallel bundle of fibers as in this strip) can be represented, for both the magnetic field and electric potential, by the same single-current dipole. First, an experimental measurement is made of the ratio of magnetic field/electric potential produced by an actual current dipole in an electrolytic tank. Then the dipole is replaced by the muscle strip and a measurement is again made of the ratio; this is done for three muscle strips at eight different source-to-detector distances ranging from 1 to 5 cm. It is found, in all cases, that the muscle ratios are equal to those of the actual dipole to within the experimental uncertainty of ±10%. Therefore, to this extent the theory is verified for this case of a thin strip of frog heart tissue.

  7. Field surveys of Midwestern and Northeastern Fish and Wildlife Service lands for the presence of abnormal frogs and toads

    USGS Publications Warehouse

    Converse, K.A.; Mattsson, J.; Eaton-Poole, L.

    2000-01-01

    The national distribution of information on the discovery of malformations in Minnesota frogs in 1995 stimulated collection and examination of newly metamorphosed frogs during 1996. By late summer and early fall of 1996, malformed frogs and toads were reported on U.S. Fish and Wildlife Service (USFWS) lands in Vermont (Northeast, Region 5) and Minnesota (Midwest, Region 3). In response to these reports, biologists in USFWS Regions 3 and 5 conducted a survey, during the summer of 1997 to determine the distribution and type of malformations in frogs and toads on selected federal lands. Region 3 personnel surveyed 38 field stations at National Wildlife Refuges (NWR's) and Wetland Management Districts. Malformed frogs and toads were collected at 23 (61%) of the Region 3 sites. External malformations were detected in 110 of 6632 individuals representing seven of 13 frog species and one of three toad species examined for an overall of 1.7% affected (percentages for affected species ranged from 0.4-5.2%). In Region 5, 17 NWR's and one National Park were surveyed. Malformed frogs were collected at 10 (56%) of the Region 5 sites. External malformations were detected in 58 of 2267 individuals representing six of 11 frog species and one of two toad species examined for an overall total of 2.6% affected (percentages for affected species ranged from 1.8-15.6%). The majority of malformations observed in frogs and toads collected in Regions 3 and 5 were partially or completely missing hind limbs and digits (50%)or malformed hind limbs and digits (14%). A few individuals had an extra limb or toe, missing or malformed front limb, missing eye, or malformation of the mandible. Despite small sample sizes at some sites, malformations were confirmed to be present in eight species of frogs and two species of toads on Federal lands in USFWS Regions 3 and 5. Further study is needed to determine the extent and distribution of amphibian malformations in these Regions. Data from this study

  8. Mechanical properties of the frog ear: vibration measurements under free- and closed-field acoustic conditions.

    PubMed

    Pinder, A C; Palmer, A R

    1983-10-22

    The acoustically induced motion of the eardrum of the frog was measured by an incoherent optical technique. When free-field sound stimulation was used, the eardrum vibration had a band-pass characteristic with maximum amplitude at 1-2.5 kHz. However, when the sound was presented in a closed-field acoustic coupler the response was low-pass (cut-off frequency about 2.5 kHz). We demonstrate that the motion is the result of the mechanical properties of the eardrum and the sound pressure acting upon it. The net pressure is due to a combination of sound incident directly on the front of the drum and of sound conducted to the rear via internal (resonant) pathways. The frog ear therefore acts as a pressure-gradient receiver at low frequency and a pressure receiver at high frequency. A model is proposed and analysed in terms of its electrical analogue. This model accounts for both our own experimental observations and those of previous studies.

  9. Deformation methods in modelling of the inner magnetospheric electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Toivanen, P. K.

    2007-12-01

    Various deformation methods have been widely used in animation image processing. In common terms, they are mathematical presentations of deformations of an image drawn on an elastic material under stretching or compression of the material. Such a method has also been used in modelling of the magnetospheric magnetic fields, and recently been generalized to include also the electric fields. In this presentations, the theory of the deformation method and an application in a form of a new global magnetospheric electromagnetic field model are previewed. The main focus of the presentation is on the inner magnetospheric current systems and associated electromagnetic fields during quiet and disturbed periods. Finally, a short look at the modern deformation methods in image processing is taken. These methods include the Free Form Deformations and Moving Least Squares Deformations, and their future applications in magnetospheric field modelling are discussed.

  10. κ-deformed oscillators, the choice of star product and free κ-deformed quantum fields

    NASA Astrophysics Data System (ADS)

    Daszkiewicz, Marcin; Lukierski, Jerzy; Woronowicz, Mariusz

    2009-09-01

    The aim of this paper is to study in D = 4 the general framework providing various κ-deformations of field oscillators and consider the commutator function of the corresponding κ-deformed free fields. In order to obtain free κ-deformed quantum fields (with c-number commutators) we proposed earlier a particular model of a κ-deformed oscillator algebra (Daszkiewicz M, Lukierski J and Woronowicz M 2008 Mod. Phys. Lett. A 23 9 (arXiv:hep-th/0703200)) and the modification of κ-star product (Daszkiewicz M, Lukierski J, Woronowicz M 2008 Phys. Rev. D 77 105007 (arXiv:0708.1561 [hep-th])), implementing in the product of two quantum fields the change of standard κ-deformed mass-shell conditions. We recall here that other different models of κ-deformed oscillators recently introduced in Arzano M and Marciano A (2007 Phys. Rev. D 76 125005 (arXiv:0707.1329 [hep-th])), Young C A S and Zegers R (2008 Nucl. Phys. B 797 537 (arXiv: 0711.2206 [hep-th])), Young C A S and Zegers R (2008 arXiv: 0803.2659 [hep-th]) are defined on a standard κ-deformed mass shell. In this paper, we consider the most general κ-deformed field oscillators, parametrized by a set of arbitrary functions in 3-momentum space. First, we study the fields with the κ-deformed oscillators defined on the standard κ-deformed mass shell, and argue that for any such choice of a κ-deformed field oscillators algebra we do not obtain the free quantum κ-deformed fields with the c-number commutators. Further, we study κ-deformed quantum fields with the modified κ-star product and derive a large class of κ-oscillators defined on a suitably modified κ-deformed mass shell. We obtain a large class of κ-deformed statistics depending on six arbitrary functions which all provide the c-number field commutator functions. This general class of κ-oscillators can be described by the composition of suitably defined κ-multiplications and the κ-deformation of the flip operator.

  11. Early embryonic development of frogs under intense magnetic fields up to 8 T

    NASA Astrophysics Data System (ADS)

    Ueno, S.; Iwasaka, M.; Shiokawa, K.

    1994-05-01

    A possible influence of intense magnetic fields on the embryonic development of frogs was studied in reference to a potential hazard in magnetic resonance imaging technology. Some of the most serious hazardous effects that could be induced by intense magnetic fields are teratogenic effects on developing embryos. In the present experiment, the possible influence of intense magnetic fields up to 8 T on the early embryonic development of Xenopus laevis was studied. Embryos were exposed to magnetic fields up to 8 T for the period from the precleavage stage to neurula in a small glass vial. Embryos were then cultured in Brown-Caston's medium until the feeding-tadpole stage. No apparent teratogenic effects were observed when embryos were cultured for 20 h from the stage of uncleaved fertilized egg to the neurula stage under magnetic fields of 8 T. We conclude that static magnetic fields up to 8 T do not appreciably affect the rapid cleavage and the following cell multiplication and differentiation in Xenopus laevis. We have also studied the early embryonic development of Xenopus laevis in a 40 nT magnetic field, or 1/1000 of the earth's magnetic field, and obtained negative results. Thus, again under this very low magnetic field, fertilized eggs developed normally and formed tadpoles with no appreciable abnormality.

  12. Does the nontrivially deformed field-antifield formalism exist?

    NASA Astrophysics Data System (ADS)

    Batalin, Igor A.; Lavrov, Peter M.

    2015-06-01

    We reformulate the Lagrange deformed field-antifield BV-formalism suggested, in terms of the general Euler vector field N generated by the antisymplectic potential. That N generalizes, in a natural anticanonically-invariant manner, the usual power-counting operator. We provide for the "usual" gauge-fixing mechanism as applied to the deformed BV-formalism.

  13. Nonclassical Properties of Q-Deformed Superposition Light Field State

    NASA Technical Reports Server (NTRS)

    Ren, Min; Shenggui, Wang; Ma, Aiqun; Jiang, Zhuohong

    1996-01-01

    In this paper, the squeezing effect, the bunching effect and the anti-bunching effect of the superposition light field state which involving q-deformation vacuum state and q-Glauber coherent state are studied, the controllable q-parameter of the squeezing effect, the bunching effect and the anti-bunching effect of q-deformed superposition light field state are obtained.

  14. Itraconazole treatment reduces Batrachochytrium dendrobatidis prevalence and increases overwinter field survival in juvenile Cascades frogs.

    PubMed

    Hardy, Bennett M; Pope, Karen L; Piovia-Scott, Jonah; Brown, Richard N; Foley, Janet E

    2015-01-15

    The global spread of the fungal pathogen Batrachochytrium dendrobatidis (Bd) has led to widespread extirpation of amphibian populations. During an intervention aimed at stabilizing at-risk populations, we treated wild-caught Cascades frogs Rana cascadae with the antifungal drug itraconazole. In fall 2012, we collected 60 recently metamorphosed R. cascadae from 1 of the 11 remnant populations in the Cascades Mountains (CA, USA). Of these, 30 randomly selected frogs were treated with itraconazole and the other 30 frogs served as experimental controls; all were released at the capture site. Bd prevalence was low at the time of treatment and did not differ between treated frogs and controls immediately following treatment. Following release, Bd prevalence gradually increased in controls but not in treated frogs, with noticeable (but still non-significant) differences 3 wk after treatment (27% [4/15] vs. 0% [0/13]) and strong differences 5 wk after treatment (67% [8/12] vs. 13% [1/8]). We did not detect any differences in Bd prevalence and load between experimental controls and untreated wild frogs during this time period. In spring 2013, we recaptured 7 treated frogs but none of the experimental control frogs, suggesting that over-winter survival was higher for treated frogs. The itraconazole treatment did appear to reduce growth rates: treated frogs weighed 22% less than control frogs 3 wk after treatment (0.7 vs. 0.9 g) and were 9% shorter than control frogs 5 wk after treatment (18.4 vs. 20.2 mm). However, for critically small populations, increased survival of the most at-risk life stage could prevent or delay extinction. Our results show that itraconazole treatment can be effective against Bd infection in wild amphibians, and therefore the beneficial effects on survivorship may outweigh the detrimental effects on growth.

  15. Inelastic deformation of conductive bodies in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Altenbach, Holm; Morachkovsky, Oleg; Naumenko, Konstantin; Lavinsky, Denis

    2016-09-01

    Inelastic deformation of conductive bodies under the action of electromagnetic fields is analyzed. Governing equations for non-stationary electromagnetic field propagation and elastic-plastic deformation are presented. The variational principle of minimum of the total energy is applied to formulate the numerical solution procedure by the finite element method. With the proposed method, distributions of vector characteristics of the electromagnetic field and tensor characteristics of the deformation process are illustrated for the inductor-workpiece system within a realistic electromagnetic forming process.

  16. 3D deformation field throughout the interior of materials.

    SciTech Connect

    Jin, Huiqing; Lu, Wei-Yang

    2013-09-01

    This report contains the one-year feasibility study for our three-year LDRD proposal that is aimed to develop an experimental technique to measure the 3D deformation fields inside a material body. In this feasibility study, we first apply Digital Volume Correlation (DVC) algorithm to pre-existing in-situ Xray Computed Tomography (XCT) image sets with pure rigid body translation. The calculated displacement field has very large random errors and low precision that are unacceptable. Then we enhance these tomography images by setting threshold of the intensity of each slice. DVC algorithm is able to obtain accurate deformation fields from these enhanced image sets and the deformation fields are consistent with the global mechanical loading that is applied to the specimen. Through this study, we prove that the internal markers inside the pre-existing tomography images of aluminum alloy can be enhanced and are suitable for DVC to calculate the deformation field throughout the material body.

  17. Dynamics of Deformable Active Particles under External Flow Field

    NASA Astrophysics Data System (ADS)

    Tarama, Mitsusuke

    2017-10-01

    In most practical situations, active particles are affected by their environment, for example, by a chemical concentration gradient, light intensity, gravity, or confinement. In particular, the effect of an external flow field is important for particles swimming in a solvent fluid. For deformable active particles such as self-propelled liquid droplets and active vesicles, as well as microorganisms such as euglenas and neutrophils, a general description has been developed by focusing on shape deformation. In this review, we present our recent studies concerning the dynamics of a single active deformable particle under an external flow field. First, a set of model equations of active deformable particles including the effect of a general external flow is introduced. Then, the dynamics under two specific flow profiles is discussed: a linear shear flow, as the simplest example, and a swirl flow. In the latter case, the scattering dynamics of the active deformable particles by the swirl flow is also considered.

  18. Dense deformation field estimation for brain intraoperative images registration

    NASA Astrophysics Data System (ADS)

    De Craene, Mathieu S.; du Bois d'Aische, Aloys; Talos, Ion-Florin; Ferrant, Matthieu; Black, Peter M.; Jolesz, Ferenc; Kikinis, Ron; Macq, Benoit; Warfield, Simon K.

    2004-05-01

    A new fast non rigid registration algorithm is presented. The algorithm estimates a dense deformation field by optimizing a criterion that measures image similarity by mutual information and regularizes with a linear elastic energy term. The optimal deformation field is found using a Simultaneous Perturbation Stochastic Approximation to the gradient. The implementation is parallelized for symmetric multi-processor architectures. This algorithm was applied to capture non-rigid brain deformations that occur during neurosurgery. Segmentation of the intra-operative data is not required but preoperative segmentation of the brain allows the algorithm to be robust to artifacts due to the craniotomy.

  19. Utility transforms of optical fields employing deformable mirror.

    PubMed

    Wang, Feiling

    2011-11-15

    Diffraction optical devices of modest degrees of freedom (DOF), such as deformable mirrors, have not been exploited as general-purpose transformers of optical fields. Described in this Letter is a method that guides deformable mirrors to optimal surfaces allowed by the DOF for various desirable outcomes. The method is based on a modal optimization procedure with the help of Walsh functions in controlling the variables of the mirrors, i.e. the actuators. It is shown that a deformable mirror of modest DOF can provide field transformations for arbitrary beam-splitting, formation of ring-shaped beams, and coherent beam combining.

  20. Density dependent growth in adult brown frogs Rana arvalis and Rana temporaria - A field experiment

    NASA Astrophysics Data System (ADS)

    Loman, Jon; Lardner, Björn

    2009-11-01

    In species with complex life cycles, density regulation can operate on any of the stages. In frogs there are almost no studies of density effects on the performance of adult frogs in the terrestrial habitat. We therefore studied the effect of summer density on the growth rate of adult frogs during four years. Four 30 by 30 m plots in a moist meadow were used. In early summer, when settled after post-breeding migration, frogs ( Rana arvalis and Rana temporaria that have a very similar ecology and potentially compete) were enclosed by erecting a fence around the plots. Frogs were captured, measured, marked and partly relocated to create two high density and two low density plots. In early autumn the frogs were again captured and their individual summer growth determined. Growth effects were evaluated in relation to two density measures: density by design (high/low manipulation), and actual (numerical) density. R. arvalis in plots with low density by design grew faster than those in high density plots. No such effect was found for R. temporaria. For none of the species was growth related to actual summer density, determined by the Lincoln index and including the density manipulation. The result suggests that R. arvalis initially settled according to an ideal free distribution and that density had a regulatory effect (mediated through growth). The fact that there were no density effects on R. temporaria (and a significant difference in its response to that of R. arvalis) suggests it is a superior competitor to R. arvalis during the terrestrial phase. There were no density effects on frog condition index, suggesting that the growth rate modifications may actually be an adaptive trait of R. arvalis. The study demonstrates that density regulation may be dependent on resources in frogs' summer habitat.

  1. Double metric, generalized metric, and α' -deformed double field theory

    NASA Astrophysics Data System (ADS)

    Hohm, Olaf; Zwiebach, Barton

    2016-03-01

    We relate the unconstrained "double metric" of the "α' -geometry" formulation of double field theory to the constrained generalized metric encoding the spacetime metric and b -field. This is achieved by integrating out auxiliary field components of the double metric in an iterative procedure that induces an infinite number of higher-derivative corrections. As an application, we prove that, to first order in α' and to all orders in fields, the deformed gauge transformations are Green-Schwarz-deformed diffeomorphisms. We also prove that to first order in α' the spacetime action encodes precisely the Green-Schwarz deformation with Chern-Simons forms based on the torsionless gravitational connection. This seems to be in tension with suggestions in the literature that T-duality requires a torsionful connection, but we explain that these assertions are ambiguous since actions that use different connections are related by field redefinitions.

  2. A Phase-field Model for Deformation Twinning

    SciTech Connect

    Heo, Tae Wook; Wang, Yi; Bhattacharya, Saswata; Sun, Xin; Hu, Shenyang Y.; Chen, Long-Qing

    2011-02-01

    We propose a phase-field model for modeling microstructure evolution during deformation twinning. Using a face-centered cubic aluminum as an example, the deformation energy as a function of shear strain is obtained using first-principle calculations. The gradient energy coefficients are fitted to the twin boundary energies and to the dislocation core energies. The elastic energy of twinned structures is included using the Khachaturyan’s elasticity theory. We simulated the twinning process under a number of fixed deformation magnitudes and predicted the microstructures.

  3. Plastic Deformation Influence on Intrinsic Magnetic Field of Austenitic Biomaterials

    NASA Astrophysics Data System (ADS)

    Smetana, Milan; Čápová, Klára; Chudáčik, Vladimír; Palček, Peter; Oravcová, Monika

    2016-12-01

    This article deals with non-destructive evaluation of austenitic stainless steels, which are used as the biomaterials in medical practice. Intrinsic magnetic field is investigated using the fluxgate sensor, after the applied plastic deformation. The three austenitic steel types are studied under the same conditions, while several values of the deformation are applied, respectively. The obtained results are presented and discussed in the paper.

  4. Deformation of Water by a Magnetic Field

    ERIC Educational Resources Information Center

    Chen, Zijun; Dahlberg, E. Dan

    2011-01-01

    After the discovery that superconducting magnets could levitate diamagnetic objects, researchers became interested in measuring the repulsion of diamagnetic fluids in strong magnetic fields, which was given the name "The Moses Effect." Both for the levitation experiments and the quantitative studies on liquids, the large magnetic fields necessary…

  5. Deformation of Water by a Magnetic Field

    ERIC Educational Resources Information Center

    Chen, Zijun; Dahlberg, E. Dan

    2011-01-01

    After the discovery that superconducting magnets could levitate diamagnetic objects, researchers became interested in measuring the repulsion of diamagnetic fluids in strong magnetic fields, which was given the name "The Moses Effect." Both for the levitation experiments and the quantitative studies on liquids, the large magnetic fields necessary…

  6. Conformal field theories from deformations of theories with Wn symmetry

    NASA Astrophysics Data System (ADS)

    Babaro, Juan Pablo; Giribet, Gaston; Ranjbar, Arash

    2016-10-01

    We construct a set of nonrational conformal field theories that consist of deformations of Toda field theory for s l (n ). In addition to preserving conformal invariance, the theories may still exhibit a remnant infinite-dimensional affine symmetry. The case n =3 is used to illustrate this phenomenon, together with further deformations that yield enhanced Kac-Moody symmetry algebras. For generic n we compute N -point correlation functions on the Riemann sphere and show that these can be expressed in terms of s l (n ) Toda field theory ((N -2 )n +2 ) -point correlation functions.

  7. Vesicle deformation and poration under strong dc electric fields

    NASA Astrophysics Data System (ADS)

    Sadik, Mohamed M.; Li, Jianbo; Shan, Jerry W.; Shreiber, David I.; Lin, Hao

    2011-06-01

    When subject to applied electric pulses, a lipid membrane exhibits complex responses including electrodeformation and electroporation. In this work, the electrodeformation of giant unilamellar vesicles under strong dc electric fields was investigated. Specifically, the degree of deformation was quantified as a function of the applied field strength and the electrical conductivity ratio of the fluids inside and outside of the vesicles. The vesicles were made from L-α-phosphatidylcholine with diameters ranging from 14 to 30 μm. Experiments were performed with field strengths ranging from 0.9 to 2.0 kV/cm, and intra-to-extra-vesicular conductivity ratios varying between 1.92 and 53.0. With these parametric configurations, the vesicles exhibited prolate elongations along the direction of the electric field. The degree of deformation was, in general, significant. In some cases, the aspect ratio of a deformed vesicle exceeded 10, representing a strong-deformation regime previously not explored. The aspect ratio scaled quadratically with the field strength, and increased asymptotically to a maximum value at high conductivity ratios. Appreciable area and volumetric changes were observed both during and after pulsation, indicating the concurrence of electroporation. A theoretical model is developed to predict these large deformations in the strongly permeabilized limit, and the results are compared with the experimental data. Both agreements and discrepancies are found, and the model limitations and possible extensions are discussed.

  8. Deformational stress fields of Casper Mountain, Wyoming

    SciTech Connect

    Burfod, A.E.; Gable, D.J.

    1985-01-01

    Casper Mountain is an east-west-trending Laramide feature located immediately west of the north termination of the Laramie Mountains in central Wyoming. Precambrian rocks are exposed as its core; off-dipping Paleozoic and Mesozoic strata characterize the flanks and ends. The north side is abruptly downthrown along a major east-west fault or faults. A complex of stress fields of Precambrian and younger ages is indicated by high-angle shears and shear zones, steep-dip foliations, and multiple joint systems. One or more of the indicated Precambrian stress fields may be equivalent to that of the Cheyenne belt of the southern Laramie Mountains. In addition, at least two well-developed Laramide stress fields were active during the formation of the mountain structure. The principal maximum compressive stress of each was oriented north-south; the mean compressive axis of one was vertical whereas in the other the minimum compressive axis was vertical. Some structural features of Precambrian age, faulting in particular, appear to have influenced structures of younger ages. Prominent east-northeast-trending, high-angle faults lie approximately parallel to the Precambrian structural grain; they offset structural features of Laramide age and may be of late Laramide and/or post-Laramide age.

  9. Effects of Altosid and Abate-4E on deformities and survival in southern leopard frogs under semi-natural conditions

    USGS Publications Warehouse

    Sparling, D.W.; Kaiser, Hinrich; Casper, Gary S.; Bernstein, Neil P.

    2000-01-01

    Experimental wetlands were sprayed with Abate-4E (a.i. temephos) and Altosid (a.i. methoprene) through the summer following label directions. In late August and early Septemeber metamorphing tadpoles were captured and examined for deformities. Tadpoles captured from ponds sprayed with Altosid had a 15% deformity rate mostly involving total or partially missing hind limbs. Tadpoles from control ponds had a 5% rate of deformities. The difference was statistically significant. The relative abundance of tadpoles from ponds sprayed with Abate-4E was significantly lower than those from Altosid-sprayed or control wetlands.

  10. Itraconazole treatment reduces Batrachochytrium dendrobatidis prevalence and increases overwinter field survival in juvenile Cascades frogs

    Treesearch

    B.M. Hardy; K.L. Pope; J. Piovia-Scott; R.N. Brown; J.E. Foley

    2015-01-01

    The global spread of the fungal pathogen Batrachochytrium dendrobatidis (Bd) has led to widespread extirpation of amphibian populations. During an intervention aimed at stabilizing at-risk populations, we treated wild-caught Cascades frogs Rana cascadae with the antifungal drug itraconazole. In fall 2012, we collected 60 recently...

  11. Deformation of an elastic capsule in a uniform electric field

    NASA Astrophysics Data System (ADS)

    Karyappa, Rahul B.; Deshmukh, Shivraj. D.; Thaokar, Rochish. M.

    2014-12-01

    The deformation of a thin elastic capsule subjected to a uniform electric field is investigated in the Stokes flow regime. The electrohydrodynamic flow is analyzed using a perfect conductor and a perfect dielectric model for the capsule and the fluid phase, respectively. A theoretical analysis is carried out using an asymptotic expansion in the electric capillary number (Ca) (a ratio of the electric stress to the elastic tension) in the small deformation limit using the finite deformation Hooke's law. The analysis is used to determine the elasticity of polysiloxane capsules suspended in oil, the deformation of which is obtained using videography. The boundary element method is implemented to seek numerical solutions to the hydrodynamic, elastic, and electrostatics equations. The finite deformation Hooke's law, the Mooney-Rivlin, and Skalak's model for elasticity are employed. The effect of electric capillary number, unstressed geometry, and the type of membrane material on the deformation of a capsule is presented in the high Ca number limit using numerical simulation. Capsules synthesized with higher monomer concentration displayed electric stress induced wrinkling process at high electric field strengths. Burst of a capsule is characterized by poration of the polymer membrane, which could be symmetric or asymmetric at the two poles, depending upon the value of the capillary number. The results should be useful in understanding the response of elastic capsules such as red blood cells and polymerized membranes, to an electric field, in applications such as electrodeformation and electroporation. It also provides a theoretical framework for a possible way of determining the elastic parameters of a capsule.

  12. Effects of raising frogs and putting pest-killing lamps in paddy fields on the prevention of rice pests and diseases

    NASA Astrophysics Data System (ADS)

    Teng, Qing; Hu, Xue-Feng; Luo, Fan; Cao, Ming-Yang

    2014-05-01

    Frogs in paddy fields become less and less due to applying large amounts of pesticides and human hunting for a long time, which causes the aggravation of rice pests and diseases. A field experiment was carried out in the suburb of Shanghai to study the effects of artificially raising frogs and putting frequency oscillation pest-killing lamps in paddy fields on the prevention of rice pests and diseases. The field experiment includes three treatments. Treatment I: 150 frogs, each 20 g in weight, per 100 m2 were put in the fields; Treatment II: a frequency oscillation pest-killing lamp was put in the fields; Treatment III: no frogs and pest-killing lamps were put in the fields. All the experimental fields were operated based on the organic faming system. The amount of organic manure, 7500 kg/hm2, was applied to the fields as base fertilizer before sowing in early June, 2013. No any chemical fertilizers and pesticides were used during the entire period of rice growth. Each treatment is in triplicate and each plot is 67 m2 in area. The results are as follows: (1) During the entire growth period, the incidences of rice pests and diseases with Treatment I and II are significantly lower than those with CK (Treatment III). The incidence of chilo suppressalis with Treatment I, II and III is 0, 0.46% and 1.69%, respectively; that of cnaphalocrocis medinalis is 7.67%, 6.62% and 10.10%, respectively; that of rice sheath blight is 0, 11.11% and 5.43%, respectively; that of rice planthopper is 4.25 per hill, 5.75 per hill and 11 per hill, respectively. (2) The grain yield of the three treatments is significantly different. That of Treatment I, II and III is 5157.73 kg/hm2, 4761.60 kg/hm2 and 3645.14kg/hm2 on average, respectively. (3) Affected by frog activities, the contents of NH4-N, available P and available K in the soil with Treatment I are significantly raised. All the above suggest that artificially raising frogs in paddy fields could effectively prevent rice pests and

  13. Optimal rotations of deformable bodies and orbits in magnetic fields.

    PubMed

    Avron, J E; Gat, O; Kenneth, O; Sivan, U

    2004-01-30

    Deformations can induce rotation with zero angular momentum where dissipation is a natural "cost function." This gives rise to an optimization problem of finding the most effective rotation with zero angular momentum. For certain plastic and viscous media in two dimensions the optimal path is the orbit of a charged particle on a surface of constant negative curvature with a magnetic field whose total flux is half a quantum unit.

  14. Superimposed maps of the monocular visual fields in the caudolateral optic tectum in the frog, Rana pipiens.

    PubMed

    Winkowski, Daniel E; Gruberg, Edward R

    2005-01-01

    The superficial layers of the frog optic tectum receive a projection from the contralateral eye that forms a point-to-point map of the visual field. The monocular part of the visual field of the contralateral eye is represented in the caudolateral region of the tectum while the binocular part of the visual field is represented in the rostromedial tectum. Within the representation of the binocular field (rostromedial tectum), the maps of visual space from each eye are aligned. The tectal representation of the binocular visual field of the ipsilateral eye is mediated through a crossed projection from the midbrain nucleus isthmi. This isthmotectal projection also terminates in the caudolateral region of the optic tectum, yet there has been no indication that it forms a functional connection. By extracellular recording in intermediate layer 7 of the caudolateral tectum, we have discovered electrical activity driven by visual stimulation in the monocular visual field of the ipsilateral eye. The units driven from the ipsilateral eye burst upon initial presentation of the stimulus. At individual layer 7 recording sites in the caudolateral tectum, the multiunit receptive field evoked from the ipsilateral eye is located at the mirror image spatial location to the multiunit receptive field driven by the contralateral eye. Thus, as revealed electrophysiologically, there are superimposed topographic maps of the monocular visual fields in the caudolateral tectum. The ipsilateral eye monocular visual field representation can be abolished by electrolytic ablation of contralateral nucleus isthmi.

  15. Advanced materials characterization based on full field deformation measurements

    NASA Astrophysics Data System (ADS)

    Carpentier, A. Paige

    Accurate stress-strain constitutive properties are essential for understanding the complex deformation and failure mechanisms for materials with highly anisotropic mechanical properties. Among such materials, glass-fiber- and carbon-fiber-reinforced polymer--matrix composites play a critical role in advanced structural designs. The large number of different methods and specimen types currently required to generate three-dimensional allowables for structural design slows down the material characterization. Also, some of the material constitutive properties are never measured due to the prohibitive cost of the specimens needed. This work shows that simple short-beam shear (SBS) specimens are well-suited for measurement of multiple constitutive properties for composite materials and that can enable a major shift toward accurate material characterization. The material characterization is based on the digital image correlation (DIC) full-field deformation measurement. The full-field-deformation measurement enables additional flexibility for assessment of stress--strain relations, compared to the conventional strain gages. Complex strain distributions, including strong gradients, can be captured. Such flexibility enables simpler test-specimen design and reduces the number of different specimen types required for assessment of stress--strain constitutive behavior. Two key elements show advantage of using DIC in the SBS tests. First, tensile, compressive, and shear stress--strain relations are measured in a single experiment. Second, a counter-intuitive feasibility of closed-form stress and modulus models, normally applicable to long beams, is demonstrated for short-beam specimens. The modulus and stress--strain data are presented for glass/epoxy and carbon/epoxy material systems. The applicability of the developed method to static, fatigue, and impact load rates is also demonstrated. In a practical method to determine stress-strain constitutive relations, the stress

  16. Detection of flashing areas attributed to the frog cardiac function in the vagosympathetic trunk placed into a high frequency electric field.

    PubMed

    Pokrovskii, V M; Abushkevich, V G; Perova, Yu Yu; Perova, M Yu; Pokhotko, A G; Ardelyan, A N

    2016-05-01

    In a high frequency electric field, two flashing areas were observed during each contraction of the heart in the vagosympathetic trunk of a paralyzed frog with an intact brain. One area with a higher diameter was moving along the nerve from the heart at a speed of 16.6 ± 0.2 m/s. It was identified as afferent. Another area with a smaller diameter was spreading along the nerve towards the venous sinus of the frog heart at a speed of 5.6 ± 0.3 m/s, and it was efferent.

  17. Study of resonant structures in a deformed mean field by the contour deformation method in momentum space

    NASA Astrophysics Data System (ADS)

    Hagen, G.; Vaagen, J. S.

    2006-03-01

    Solution of the momentum space Schrödinger equation in the case of deformed fields is being addressed. In particular it is shown that a complete set of single-particle states that includes bound, resonant, and complex continuum states may be obtained by the contour deformation method. This generalized basis in the complex energy plane is known as a Berggren basis. The momentum space Schrödinger equation is an integral equation that is easily solved by matrix diagonalization routines even for the case of deformed fields. The method is demonstrated for axial symmetry and a fictitious “deformed He5” but may be extended to more general deformation and applied to truly deformed halo nuclei.

  18. Geodesics in the field of a rotating deformed gravitational source

    NASA Astrophysics Data System (ADS)

    Boshkayev, K. A.; Quevedo, H.; Abutalip, M. S.; Kalymova, Zh. A.; Suleymanova, Sh. S.

    2016-01-01

    We investigate equatorial geodesics in the gravitational field of a rotating and deformed source described by the approximate Hartle-Thorne metric. In the case of massive particles, we derive within the same approximation analytic expressions for the orbital angular velocity, the specific angular momentum and energy, and the radii of marginally stable and marginally bound circular orbits. Moreover, we calculate the orbital angular velocity and the radius of lightlike circular geodesics. We study numerically the frame dragging effect and the influence of the quadrupolar deformation of the source on the motion of test particles. We show that the effects originating from the rotation can be balanced by the effects due to the oblateness of the source.

  19. Awareness of the light field: the case of deformation

    PubMed Central

    van Doorn, Andrea J.; Koenderink, Jan J.; Todd, James T.; Wagemans, Johan

    2012-01-01

    Human observers group local shading patterns into global super-patterns that appear to be illuminated in some unitary fashion. Many years ago, this was noticed for the case of uniform, unidirectional illumination. Recently, we found that it also applies to convergent and divergent illumination flows, but that human observers are blind to rotational light flow patterns (in the sense of being unable to group the local shading patterns). We now report that human observers are also blind to deformation patterns. This is perhaps interesting because convergent, divergent, rotational, and deformation patterns all occur in natural light fields. This is an idiosyncrasy of the human visual system, on par with the fact that visual awareness fails to present the observer with saddle shapes. PMID:23145298

  20. Analytic regularization of uniform cubic B-spline deformation fields.

    PubMed

    Shackleford, James A; Yang, Qi; Lourenço, Ana M; Shusharina, Nadya; Kandasamy, Nagarajan; Sharp, Gregory C

    2012-01-01

    Image registration is inherently ill-posed, and lacks a unique solution. In the context of medical applications, it is desirable to avoid solutions that describe physically unsound deformations within the patient anatomy. Among the accepted methods of regularizing non-rigid image registration to provide solutions applicable to medical practice is the penalty of thin-plate bending energy. In this paper, we develop an exact, analytic method for computing the bending energy of a three-dimensional B-spline deformation field as a quadratic matrix operation on the spline coefficient values. Results presented on ten thoracic case studies indicate the analytic solution is between 61-1371x faster than a numerical central differencing solution.

  1. Kerosene wick lamp flame deformation in gradient magnetic fields

    NASA Astrophysics Data System (ADS)

    Saeedi, A.; Moghiman, M.

    2014-03-01

    The behavior of a kerosene wick lamp flame in the presence of non-uniform DC magnetic fields has been investigated and the results of this experimental study are presented. It has long been recognized that magnetic fields can influence the behavior of diffusion flames as a result of the paramagnetic and diamagnetic properties of the constituent gases. Using an electromagnet consisting of two coils and cores to generate a horizontal magnetic field, a non-uniform upward increasing and decreasing magnetic field was applied to a kerosene wick lamp flame. The experimental results show that the influence of DC gradient magnetic field on diffusion flame structure deformation depends on the flame position in the increasing or decreasing magnetic field, the flame situation relative to the maximum of the absolute value of the gradient and the quantity of the gradient magnetic field. It was also observed that both flame front area and flame height decrease in the positive and negative gradient field below the maximum of the absolute value of the gradient. Also, increasing the absolute of the gradient of the square magnetic induction in the positive and negative gradient field above the maximum of the absolute value of the gradient cause to elongate the flame and increase in the flame front area and then the flame height and front area decrease.

  2. Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Rana pipiens): laboratory and field evidence.

    PubMed

    Hayes, Tyrone; Haston, Kelly; Tsui, Mable; Hoang, Anhthu; Haeffele, Cathryn; Vonk, Aaron

    2003-04-01

    Atrazine is the most commonly used herbicide in the United States and probably the world. Atrazine contamination is widespread and can be present in excess of 1.0 ppb even in precipitation and in areas where it is not used. In the current study, we showed that atrazine exposure (> or = to 0.1 ppb) resulted in retarded gonadal development (gonadal dysgenesis) and testicular oogenesis (hermaphroditism) in leopard frogs (Rana pipiens). Slower developing males even experienced oocyte growth (vitellogenesis). Furthermore, we observed gonadal dysgenesis and hermaphroditism in animals collected from atrazine-contaminated sites across the United States. These coordinated laboratory and field studies revealed the potential biological impact of atrazine contamination in the environment. Combined with reported similar effects in Xenopus laevis, the current data raise concern about the effects of atrazine on amphibians in general and the potential role of atrazine and other endocrine-disrupting pesticides in amphibian declines.

  3. Atrazine-induced hermaphroditism at 0.1 ppb in American leopard frogs (Rana pipiens): laboratory and field evidence.

    PubMed Central

    Hayes, Tyrone; Haston, Kelly; Tsui, Mable; Hoang, Anhthu; Haeffele, Cathryn; Vonk, Aaron

    2003-01-01

    Atrazine is the most commonly used herbicide in the United States and probably the world. Atrazine contamination is widespread and can be present in excess of 1.0 ppb even in precipitation and in areas where it is not used. In the current study, we showed that atrazine exposure (> or = to 0.1 ppb) resulted in retarded gonadal development (gonadal dysgenesis) and testicular oogenesis (hermaphroditism) in leopard frogs (Rana pipiens). Slower developing males even experienced oocyte growth (vitellogenesis). Furthermore, we observed gonadal dysgenesis and hermaphroditism in animals collected from atrazine-contaminated sites across the United States. These coordinated laboratory and field studies revealed the potential biological impact of atrazine contamination in the environment. Combined with reported similar effects in Xenopus laevis, the current data raise concern about the effects of atrazine on amphibians in general and the potential role of atrazine and other endocrine-disrupting pesticides in amphibian declines. PMID:12676617

  4. FULL-FIELD DEFORMATION MEASUREMENT IN POLYMERIC FOAM SPECIMENS

    SciTech Connect

    C. LIU; ET AL

    2001-03-01

    In this investigation, a simple experimental technique, dot-matrix deposition and mapping, was developed to study the full-field deformation in a polymeric foam specimen. One of the advantages of using this technique is that it can be easily applied to situations where large deformations are involved. The spatial resolution of the current technique is not as high as the digital image correlation method and some other optical techniques. Nevertheless, because the largest cell diameter of the polyurethane foam studied in this investigation is about 1 mm, the smallest length scale over which the polymeric foam material can be treated as a homogeneous solid would be at least several millimeters. For the element size used in the present study in the range of 2.5 x 2.5 mm, the dot-matrix deposition and mapping technique would provide enough detail about the behavior of polymeric foam materials under complicated deformation states and under complicated loading conditions. It will also provide useful information to compare with numerical simulations so that the constitutive models can be validated.

  5. Impacts of the herbicide butachlor on the larvae of a paddy field breeding frog (Fejervarya limnocharis) in subtropical Taiwan

    USGS Publications Warehouse

    Liu, Wan-Yi; Wang, Ching-Yuh; Wang, Tsu-Shing; Fellers, Gary M.; Lai, Bo-Chi; Kam, Yeong-Choy

    2011-01-01

    Butachlor is the most commonly used herbicide on paddy fields in Taiwan and throughout Southeast Asia. Since paddy fields provide habitat for pond breeding amphibians, we examined growth, development, time to metamorphosis, and survival of alpine cricket frog tadpoles (Fejervarya limnocharis) exposed to environmentally realistic concentrations of butachlor. We documented negative impacts of butachlor on survival, development, and time to metamorphosis, but not on tadpole growth. The 96 h LC50 for tadpoles was 0.87 mg/l, much lower than the 4.8 mg/l recommended dosage for application to paddy fields. Even given the rapid breakdown of butachlor, tadpoles would be exposed to concentrations in excess of their 96 h LC50 for an estimated 126 h. We also documented DNA damage (genotoxicity) in tadpoles exposed to butachlor at concentrations an order of magnitude less than the 4.8 mg/l recommended application rate. We did not find that butachlor depressed cholinesterase activity of tadpoles, unlike most organophosphorus insecticides. We conclude that butachlor is likely to have widespread negative impacts on amphibians occupying paddy fields with traditional herbicide application.

  6. Landscape resistance to frog movements

    USGS Publications Warehouse

    Mazerolle, M.J.; Desrochers, A.

    2005-01-01

    An animal's capacity to recolonize a patch depends on at least two components: its ability to detect the patch and its ability to reach it. However, the disruption of such processes by anthropic disturbances could explain low animal abundance patterns observed by many investigators in certain landscapes. Through field experiments, we compared the orientation and homing success of northern green frogs (Rana clamitans melanota Rafinesque, 1820) and northern leopard frogs (Rana pipiens Schreber, 1782) translocated across disturbed or undisturbed surfaces. We also monitored the path selected by individuals when presented with a choice between a short distance over a disturbed surface and a longer, undisturbed route. Finally, we measured the water loss and behaviour of frogs on substrates resulting from anthropogenic disturbances and a control. When presented with a choice, 72% of the frogs avoided disturbed surfaces. Although able to orient towards the pond of capture when translocated on disturbed surfaces, frogs had a lower probability of homing successfully to the pond than when translocated at a similar distance on an undisturbed surface. Frogs lost the most water on substrates associated with disturbance and in the absence of cover. Our data illustrate that anthropically disturbed areas devoid of cover, such as mined peatlands and agricultural fields, disrupt the ability of frogs to reach habitat patches and are likely explanations to their reduced abundance patterns in such environments. ?? 2005 NRC Canada.

  7. Deformation field validation and inversion applied to adaptive radiation therapy

    NASA Astrophysics Data System (ADS)

    Vercauteren, Tom; De Gersem, Werner; Olteanu, Luiza A. M.; Madani, Indira; Duprez, Fréderic; Berwouts, Dieter; Speleers, Bruno; De Neve, Wilfried

    2013-08-01

    Development and implementation of chronological and anti-chronological adaptive dose accumulation strategies in adaptive intensity-modulated radiation therapy (IMRT) for head-and-neck cancer. An algorithm based on Newton iterations was implemented to efficiently compute inverse deformation fields (DFs). Four verification steps were performed to ensure a valid dose propagation: intra-cell folding detection finds zero or negative Jacobian determinants in the input DF; inter-cell folding detection is implemented on the resolution of the output DF; a region growing algorithm detects undefined values in the output DF; DF domains can be composed and displayed on the CT data. In 2011, one patient with nonmetastatic head and neck cancer selected from a three phase adaptive DPBN study was used to illustrate the algorithms implemented for adaptive chronological and anti-chronological dose accumulation. The patient received three 18F-FDG-PET/CTs prior to each treatment phase and one CT after finalizing treatment. Contour propagation and DF generation between two consecutive CTs was performed in Atlas-based autosegmentation (ABAS). Deformable image registration based dose accumulations were performed on CT1 and CT4. Dose propagation was done using combinations of DFs or their inversions. We have implemented a chronological and anti-chronological dose accumulation algorithm based on DF inversion. Algorithms were designed and implemented to detect cell folding.

  8. Deformation fields near a steady fatigue crack with anisotropic plasticity

    SciTech Connect

    Gao, Yanfei

    2015-11-30

    In this work, from finite element simulations based on an irreversible, hysteretic cohesive interface model, a steady fatigue crack can be realized if the crack extension exceeds about twice the plastic zone size, and both the crack increment per loading cycle and the crack bridging zone size are smaller than the plastic zone size. The corresponding deformation fields develop a plastic wake behind the crack tip and a compressive residual stress field ahead of the crack tip. In addition, the Hill’s plasticity model is used to study the role of plastic anisotropy on the retardation of fatigue crack growth and the elastic strain fields. It is found that for Mode-I cyclic loading, an enhanced yield stress in directions that are inclined from the crack plane will lead to slower crack growth rate, but this retardation is insignificant for typical degrees of plastic anisotropy. Furthermore, these results provide key inputs for future comparisons to neutron and synchrotron diffraction measurements that provide full-field lattice strain mapping near fracture and fatigue crack tips, especially in textured materials such as wrought or rolled Mg alloys.

  9. Deformation fields near a steady fatigue crack with anisotropic plasticity

    DOE PAGES

    Gao, Yanfei

    2015-11-30

    In this work, from finite element simulations based on an irreversible, hysteretic cohesive interface model, a steady fatigue crack can be realized if the crack extension exceeds about twice the plastic zone size, and both the crack increment per loading cycle and the crack bridging zone size are smaller than the plastic zone size. The corresponding deformation fields develop a plastic wake behind the crack tip and a compressive residual stress field ahead of the crack tip. In addition, the Hill’s plasticity model is used to study the role of plastic anisotropy on the retardation of fatigue crack growth andmore » the elastic strain fields. It is found that for Mode-I cyclic loading, an enhanced yield stress in directions that are inclined from the crack plane will lead to slower crack growth rate, but this retardation is insignificant for typical degrees of plastic anisotropy. Furthermore, these results provide key inputs for future comparisons to neutron and synchrotron diffraction measurements that provide full-field lattice strain mapping near fracture and fatigue crack tips, especially in textured materials such as wrought or rolled Mg alloys.« less

  10. Variation after projection with a triaxially deformed nuclear mean field

    NASA Astrophysics Data System (ADS)

    Gao, Zao-Chun; Horoi, Mihai; Chen, Y. S.

    2015-12-01

    We implemented a variation after projection (VAP) algorithm based on a triaxially deformed Hartree-Fock-Bogoliubov vacuum state. This is the first projected mean field study that includes all the quantum numbers (except parity), i.e., spin (J ), isospin (T ), and mass number (A ). Systematic VAP calculations with JTA projection have been performed for the even-even s d -shell nuclei with the USDB Hamiltonian. All the VAP ground state energies are within 500 keV above the exact shell model values. Our VAP calculations show that the spin projection has two important effects: (1) the spin projection is crucial in achieving good approximation of the full shell model calculation; (2) the intrinsic shapes of the VAP wave functions with spin projection are always triaxial, while the Hartree-Fock-Bogoliubov methods likely provide axial intrinsic shapes. Finally, our analysis suggests that one may not be possible to associate an intrinsic shape to an exact shell model wave function.

  11. Determination of the Pressure Field in a Reservoir-Deformed Bed Exposed to Vibrowaves

    NASA Astrophysics Data System (ADS)

    Abbasov, É. M.; Agaeva, N. A.

    2017-01-01

    On the basis of theoretical investigations, the authors have determined the pressure field in a deformable bed exposed to vibrowaves. A study has been made of the propagation of various forms of elastic waves in a deformable bed. An analytical expression has been obtained for the bottom-hole pressure with account of the deformation of thebed's reservoir. It has been shown that the degree of attenuation of elastic waves in beds with deformable reservoirs increases strongly compared to undeformable ones.

  12. Fantastic Frogs!

    ERIC Educational Resources Information Center

    Scott, Kym

    2002-01-01

    Number rhymes can be used in many exciting and different ways to support the early learning goals for mathematics. The rhyme "five little speckled frogs" provides the theme for this display, which was set up in Lewisham's professional development center. It provides a range of ideas which would help develop young children's mathematical learning…

  13. Fantastic Frogs!

    ERIC Educational Resources Information Center

    Scott, Kym

    2002-01-01

    Number rhymes can be used in many exciting and different ways to support the early learning goals for mathematics. The rhyme "five little speckled frogs" provides the theme for this display, which was set up in Lewisham's professional development center. It provides a range of ideas which would help develop young children's mathematical learning…

  14. FROGS report

    NASA Astrophysics Data System (ADS)

    FROGS Reports present information on current research relevant to felsic magmatism, including commentaries on problems of current interest. Please contact Calvin Miller, Geology, 6028B, Vanderbilt University, Nashville, TN 37235; tel. 615-322-2986 about your own research, conferences, and ideas for stimulating commentaries.

  15. Observing earthquakes triggered in the near field by dynamic deformations

    USGS Publications Warehouse

    Gomberg, J.; Bodin, P.; Reasenberg, P.A.

    2003-01-01

    We examine the hypothesis that dynamic deformations associated with seismic waves trigger earthquakes in many tectonic environments. Our analysis focuses on seismicity at close range (within the aftershock zone), complementing published studies of long-range triggering. Our results suggest that dynamic triggering is not confined to remote distances or to geothermal and volcanic regions. Long unilaterally propagating ruptures may focus radiated dynamic deformations in the propagation direction. Therefore, we expect seismicity triggered dynamically by a directive rupture to occur asymmetrically, with a majority of triggered earthquakes in the direction of rupture propagation. Bilaterally propagating ruptures also may be directive, and we propose simple criteria for assessing their directivity. We compare the inferred rupture direction and observed seismicity rate change following 15 earthquakes (M 5.7 to M 8.1) that occured in California and Idaho in the United States, the Gulf of Aqaba, Syria, Guatemala, China, New Guinea, Turkey, Japan, Mexico, and Antarctica. Nine of these mainshocks had clearly directive, unilateral ruptures. Of these nine, seven apparently induced an asymmetric increase in seismicity rate that correlates with the rupture direction. The two exceptions include an earthquake preceded by a comparable-magnitude event on a conjugate fault and another for which data limitations prohibited conclusive results. Similar (but weaker) correlations were found for the bilaterally rupturing earthquakes we studied. Although the static stress change also may trigger seismicity, it and the seismicity it triggers are expected to be similarly asymmetric only if the final slip is skewed toward the rupture terminus. For several of the directive earthquakes, we suggest that the seismicity rate change correlates better with the dynamic stress field than the static stress change.

  16. Tectonic field and deformation in Chalkidiki area, Greece

    NASA Astrophysics Data System (ADS)

    Alatza, Stavroula-Drosoula; Marinou, Aggeliki; Anastasiou, Demitris; Papanikolaou, Xanthos; Paradissis, Demitris

    2015-04-01

    Greece is situated on the convergence limits, between the Eurasian and the African lithospheric plate, and as a consequence, is considered as one of the most seismogenic areas on the world. Chalkidiki is part of the region of Central Macedonia in Northen Greece. The region of Chalkidiki is traversed by three faults and it is an area of great tectonic interest. On a daily basis, earthquakes occur in the seabed between the three peninsulas of Chalkidiki. Concerning the geomorphology of the area, it is covered by three types of rocks, the Serbomacedonian mass, the Perirodopiki zone and Peonia sub zone. The contact with the Serbomacedonian mass has a direct effect on tectonics of the region, since the area has a continuous tectonic activity. The neotectonic activity is characterized by normal faults, as well as horns and tectonic trenches. Velocity field and strain parameters for a deformation model are evaluated using GPS data from a geodetic network of thirty one points established in the broader area of Chalkidiki. Apart from these points, all the available observations of permanent stations in the area, were used to determine the final tectonic velocity field. All data were processed using Bernese GNSS Software v.5. The implementation of the reference system ITRF2005, was performed, using nine IGS stations, for the local network. Time series analysis for each point was used, in order to calculate the displacements and tectonic velocities. Finally, in order to investigate the strain patterns of the area, strain tensors were computed and discussed.

  17. Electric-field-induced front deformation of Belousov-Zhabotinsky waves

    NASA Astrophysics Data System (ADS)

    Ševčíková, Hana; Müller, Stefan C.

    1999-07-01

    Experimental evidence is given of deformations in the vertical profiles of ferroin-catalyzed Belousov-Zhabotinsky waves propagating in thin horizontal cuvettes under an imposed dc electric field. While no deformations are seen in a zero field, for low negative field, or for any positive field, a pronounced S-shaped deformation does occur when a wave is exposed to a negative field above some critical magnitude. The observed phenomena are discussed on the basis of the convective flows that are assumed to increase in the negative field resulting from changes in the longitudinal profile of the wave.

  18. Thermal deformation of concentrators in an axisymmetric temperature field

    NASA Technical Reports Server (NTRS)

    Bairamov, R.; Machuev, Y. I.; Nazarov, A.; Sokolov, Y. V.; Solodovnikova, L. A.; Fokin, V. G.

    1985-01-01

    Axisymmetric thermal deformations of paraboloid mirrors, due to heating, are examined for a mirror with a optical axis oriented toward the Sun. A governing differential equation is derived using Mushtari-Donnel-Vlasov simplifications, and a solution is presented which makes it possible to determine the principal deformation characteristics.

  19. Deformed neutron stars due to strong magnetic field in terms of relativistic mean field theories

    NASA Astrophysics Data System (ADS)

    Yanase, Kota; Yoshinaga, Naotaka

    2014-09-01

    Some observations suggest that magnetic field intensity of neutron stars that have particularly strong magnetic field, magnetars, reaches values up to 1014-15G. It is expected that there exists more strong magnetic field of several orders of magnitude in the interior of such stars. Neutron star matter is so affected by magnetic fields caused by intrinsic magnetic moments and electric charges of baryons that masses of neutron stars calculated by using Tolman-Oppenheimer-Volkoff equation is therefore modified. We calculate equation of state (EOS) in density-dependent magnetic field by using sigma-omega-rho model that can reproduce properties of stable nuclear matter in laboratory Furthermore we calculate modified masses of deformed neutron stars.

  20. Strategies for assessing the implications of malformed frogs for environmental health.

    PubMed Central

    Burkhart, J G; Ankley, G; Bell, H; Carpenter, H; Fort, D; Gardiner, D; Gardner, H; Hale, R; Helgen, J C; Jepson, P; Johnson, D; Lannoo, M; Lee, D; Lary, J; Levey, R; Magner, J; Meteyer, C; Shelby, M D; Lucier, G

    2000-01-01

    The recent increase in the incidence of deformities among natural frog populations has raised concern about the state of the environment and the possible impact of unidentified causative agents on the health of wildlife and human populations. An open workshop on Strategies for Assessing the Implications of Malformed Frogs for Environmental Health was convened on 4-5 December 1997 at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina. The purpose of the workshop was to share information among a multidisciplinary group with scientific interest and responsibility for human and environmental health at the federal and state level. Discussions highlighted possible causes and recent findings directly related to frog deformities and provided insight into problems and strategies applicable to continuing investigation in several areas. Possible causes of the deformities were evaluated in terms of diagnostics performed on field amphibians, biologic mechanisms that can lead to the types of malformations observed, and parallel laboratory and field studies. Hydrogeochemistry must be more integrated into environmental toxicology because of the pivotal role of the aquatic environment and the importance of fates and transport relative to any potential exposure. There is no indication of whether there may be a human health factor associated with the deformities. However, the possibility that causal agents may be waterborne indicates a need to identify the relevant factors and establish the relationship between environmental and human health in terms of hazard assessment. PMID:10620528

  1. Deformed Heisenberg algebra, fractional spin fields, and supersymmetry without fermions

    SciTech Connect

    Plyushchay, M.S.

    1996-02-01

    Within a group-theoretical approach to the description of (2+1)-dimensional anyons, the minimal covariant set of linear differential equations is constructed for the fractional spin fields with the help of the deformed Heisenberg algebra (DHA), [{ital a}{sup {minus}},{ital a}{sup +}]=1+{nu}{ital K}, involving the Klein operator {ital K}, {l_brace}{ital K},{ital a}{sup {plus_minus}}{r_brace}=0, {ital K}{sup 2}=1. The connection of the minimal set of equations with the earlier proposed {open_quote}{open_quote}universal{close_quote}{close_quote} vector set of anyon equations is established. On the basis of this algebra, a bosonization of supersymmetric quantum mechanics is carried out. The construction comprises the cases of exact and spontaneously broken {ital N}=2 supersymmetry allowing us to realize a Bose{endash}Fermi transformation and spin-1/2 representation of SU(2) group in terms of one bosonic oscillator. The construction admits an extension to the case of OSp(2{parallel}2) supersymmetry, and, as a consequence, both applications of the DHA turn out to be related. The possibility of {open_quote}{open_quote}superimposing{close_quote}{close_quote} the two applications of the DHA for constructing a supersymmetric (2+1)-dimensional anyon system is discussed. As a consequential result we point out that the {ital osp}(2{parallel}2) superalgebra is realizable as an operator algebra for a quantum mechanical 2-body (nonsupersymmetric) Calogero model. Copyright {copyright} 1996 Academic Press, Inc.

  2. Massless conformal fields, AdS(d+1)/CFTd higher spin algebras and their deformations

    DOE PAGES

    Fernando, Sudarshan; Gunaydin, Murat

    2016-02-04

    Here, we extend our earlier work on the minimal unitary representation of SO(d, 2)and its deformations for d=4, 5and 6to arbitrary dimensions d. We show that there is a one-to-one correspondence between the minrep of SO(d, 2)and its deformations and massless conformal fields in Minkowskian spacetimes in ddimensions. The minrep describes a massless conformal scalar field, and its deformations describe massless conformal fields of higher spin. The generators of Joseph ideal vanish identically as operators for the quasiconformal realization of the minrep, and its enveloping algebra yields directly the standard bosonic AdS(d+1)/CFTd higher spin algebra. For deformed minreps the generatorsmore » of certain deformations of Joseph ideal vanish as operators and their enveloping algebras lead to deformations of the standard bosonic higher spin algebra. In odd dimensions there is a unique deformation of the higher spin algebra corresponding to the spinor singleton. In even dimensions one finds infinitely many deformations of the higher spin algebra labelled by the eigenvalues of Casimir operator of the little group SO(d–2)for massless representations.« less

  3. Large stable deformation of dielectric elastomers driven on mode of steady electric field

    NASA Astrophysics Data System (ADS)

    Zhang, Junshi; Zhao, Jianwen; Wang, Shu; Chen, Hualing; Li, Dichen

    2017-05-01

    Dielectric elastomers (DEs) are capable of large deformation under the actuation of applied voltage and sprayed charge. Actuation of DE under voltage control is prone to electromechanical instabilities, while the DE under charge control always survives from instabilities with sacrificing a large deformation. In this article, a novel actuation mode of steady electric field is proposed. By tuning applied voltage and sprayed charge during viscoelastic creep, an invariable electric field is generated. Such an actuation method can both avoid the occurrence of electromechanical instabilities and guarantee a large deformation in DE actuation.

  4. Fitting a Structured Juvenile-Adult Model for Green Tree Frogs to Population Estimates from Capture-Mark-Recapture Field Data

    USGS Publications Warehouse

    Ackleh, A.S.; Carter, J.; Deng, K.; Huang, Q.; Pal, N.; Yang, X.

    2012-01-01

    We derive point and interval estimates for an urban population of green tree frogs (Hyla cinerea) from capture-mark-recapture field data obtained during the years 2006-2009. We present an infinite-dimensional least-squares approach which compares a mathematical population model to the statistical population estimates obtained from the field data. The model is composed of nonlinear first-order hyperbolic equations describing the dynamics of the amphibian population where individuals are divided into juveniles (tadpoles) and adults (frogs). To solve the least-squares problem, an explicit finite difference approximation is developed. Convergence results for the computed parameters are presented. Parameter estimates for the vital rates of juveniles and adults are obtained, and standard deviations for these estimates are computed. Numerical results for the model sensitivity with respect to these parameters are given. Finally, the above-mentioned parameter estimates are used to illustrate the long-time behavior of the population under investigation. ?? 2011 Society for Mathematical Biology.

  5. Application of deformation theory for integrated modeling of gravity gradiometry and magnetic field data

    NASA Astrophysics Data System (ADS)

    Erkan, K.; Jekeli, C.

    2009-12-01

    Today gravity and magnetic field measurements are acquired in grids with high resolution and accuracy. Magnetic field measurements have already been proven for superior accuracy and practicality. Modern gravity gradiometry instruments have boosted the practicality of gravity field measurements for many subsurface problems. As a result of this, advanced algorithms are needed for quantitative integration of the two fields for a specific subsurface problem. These fields are correlated by Poisson relation as a first order approximation. However, subsurface sources generally show large deviations from the ideal conditions; in this case a generalized Poisson relation may be proposed as a perturbation of the ideal conditions. In this study, we take advantage of the abstraction of the deformation theory between two metric fields, and implement it between the two geophysical fields. In this generalized approach, the different geophysical fields are loosely correlated by Poisson relation; so the calculated deformation reflects the deviations from ideal density/susceptibility relationships for the subsurface structure. The resulting deformation field can then be used for detection of a known target with an expected deformation field. The present method introduces a novel algorithm for integration of the gravity gradiometry and magnetic field data. In this method, the results can be directly interpreted without making individual density and magnetic susceptibility assumptions. The method also intrinsically overcomes the scale problem between the two potential fields.

  6. Real analytic solutions for marginal deformations in open superstring field theory

    NASA Astrophysics Data System (ADS)

    Okawa, Yuji

    2007-09-01

    We construct analytic solutions for marginal deformations satisfying the reality condition in open superstring field theory formulated by Berkovits when operator products made of the marginal operator and the associated superconformal primary field are regular. Our strategy is based on the recent observation by Erler that the problem of finding solutions for marginal deformations in open superstring field theory can be reduced to a problem in the bosonic theory of finding a finite gauge parameter for a certain pure-gauge configuration labeled by the parameter of the marginal deformation. We find a gauge transformation generated by a real gauge parameter which infinitesimally changes the deformation parameter and construct a finite gauge parameter by its path-ordered exponential. The resulting solution satisfies the reality condition by construction.

  7. Deformation of doubly clamped single-walled carbon nanotubes in an electrostatic field.

    PubMed

    Wang, Zhao; Philippe, Laetitia

    2009-05-29

    In this Letter, we demonstrate a strong dependence of the electrostatic deformation of doubly clamped single-walled carbon nanotubes on both the field strength and the tube length, using molecular simulations. Metallic nanotubes are found to be more sensitive to an electric field than semiconducting ones of the same size. For a given electric field, the induced deformation increases with tube length but decreases with tube radius. Furthermore, it is found that nanotubes can be more efficiently bent in a center-oriented transverse electric field.

  8. Anatomy of a deformed symmetry: Field quantization on curved momentum space

    SciTech Connect

    Arzano, Michele

    2011-01-15

    In certain scenarios of deformed relativistic symmetries relevant for noncommutative field theories particles exhibit a momentum space described by a non-Abelian group manifold. Starting with a formulation of phase space for such particles which allows for a generalization to include group-valued momenta we discuss quantization of the corresponding field theory. Focusing on the particular case of {kappa}-deformed phase space we construct the one-particle Hilbert space and show how curvature in momentum space leads to an ambiguity in the quantization procedure reminiscent of the ambiguities one finds when quantizing fields in curved space-times. The tools gathered in the discussion on quantization allow for a clear definition of the basic deformed field mode operators and two-point function for {kappa}-quantum fields.

  9. Frog eat frog: exploring variables influencing anurophagy

    PubMed Central

    Vimercati, Giovanni; de Villiers, F. André; Mokhatla, Mohlamatsane M.; Davies, Sarah J.; Edwards, Shelley; Altwegg, Res

    2015-01-01

    Background. Frogs are generalist predators of a wide range of typically small prey items. But descriptions of dietary items regularly include other anurans, such that frogs are considered to be among the most important of anuran predators. However, the only existing hypothesis for the inclusion of anurans in the diet of post-metamorphic frogs postulates that it happens more often in bigger frogs. Moreover, this hypothesis has yet to be tested. Methods. We reviewed the literature on frog diet in order to test the size hypothesis and determine whether there are other putative explanations for anurans in the diet of post-metamorphic frogs. In addition to size, we recorded the habitat, the number of other sympatric anuran species, and whether or not the population was invasive. We controlled for taxonomic bias by including the superfamily in our analysis. Results. Around one fifth of the 355 records included anurans as dietary items of populations studied, suggesting that frogs eating anurans is not unusual. Our data showed a clear taxonomic bias with ranids and pipids having a higher proportion of anuran prey than other superfamilies. Accounting for this taxonomic bias, we found that size in addition to being invasive, local anuran diversity, and habitat produced a model that best fitted our data. Large invasive frogs that live in forests with high anuran diversity are most likely to have a higher proportion of anurans in their diet. Conclusions. We confirm the validity of the size hypothesis for anurophagy, but show that there are additional significant variables. The circumstances under which frogs eat frogs are likely to be complex, but our data may help to alert conservationists to the possible dangers of invading frogs entering areas with threatened anuran species. PMID:26336644

  10. Numerical simulation of the red blood cell aggregation and deformation behaviors in ultrasonic field.

    PubMed

    Ma, Xiaojian; Huang, Biao; Wang, Guoyu; Fu, Xiaoying; Qiu, Sicong

    2016-08-16

    The objective of this paper is to propose an immersed boundary lattice Boltzmann method (IB-LBM) considering the ultrasonic effect to simulate red blood cell (RBC) aggregation and deformation in ultrasonic field. Numerical examples involving the typical streamline, normalized out-of-plane vorticity contours and vector fields in pure plasma under three different ultrasound intensities are presented. Meanwhile, the corresponding transient aggregation behavior of RBCs, with special emphasis on the detailed process of RBC deformation, is shown. The numerical results reveal that the ultrasound wave acted on the pure plasma can lead to recirculation flow, which contributes to the RBCs aggregation and deformation in microvessel. Furthermore, increasing the intensity of the ultrasound wave can significantly enhance the aggregation and deformation of the RBCs. And the formation of the RBCs aggregation leads to the fluctuated and dropped vorticity value of plasma in return.

  11. On the Uniqueness of FROG Methods

    NASA Astrophysics Data System (ADS)

    Bendory, Tamir; Sidorenko, Pavel; Eldar, Yonina C.

    2017-05-01

    The problem of recovering a signal from its power spectrum, called phase retrieval, arises in many scientific fields. One of many examples is ultra-short laser pulse characterization in which the electromagnetic field is oscillating with ~10^15 Hz and phase information cannot be measured directly due to limitations of the electronic sensors. Phase retrieval is ill-posed in most cases as there are many different signals with the same Fourier transform magnitude. To overcome this fundamental ill-posedness, several measurement techniques are used in practice. One of the most popular methods for complete characterization of ultra-short laser pulses is the Frequency-Resolved Optical Gating (FROG). In FROG, the acquired data is the power spectrum of the product of the unknown pulse with its delayed replica. Therefore the measured signal is a quartic function of the unknown pulse. A generalized version of FROG, where the delayed replica is replaced by a second unknown pulse, is called blind FROG. In this case, the measured signal is quadratic with respect to both pulses. In this letter we introduce and formulate FROG-type techniques. We then show that almost all band-limited signals are determined uniquely, up to trivial ambiguities, by blind FROG measurements (and thus also by FROG), if in addition we have access to the signals power spectrum.

  12. Inverse FEM for Full-Field Reconstruction of Elastic Deformations in Shear Deformable Plates and Shells

    NASA Technical Reports Server (NTRS)

    Tessler, Alexander; Spangler, Jan L.

    2004-01-01

    The inverse problem of real-time reconstruction of full-field structural displacements is addressed through the application of a new variational formulation leading to versatile, robust and computationally efficient inverse shell finite element analysis. Utilizing surface strain measurements from strain sensors mounted on the load-carrying structural components, the methodology enables accurate computations of the three-dimensional displacement field. This high fidelity computational technology is essential for providing feedback to the actuation and control systems of the next generation of aerospace vehicles.

  13. Gauge-invariant observables and marginal deformations in open string field theory

    NASA Astrophysics Data System (ADS)

    Kudrna, Matěj; Masuda, Toru; Okawa, Yuji; Schnabl, Martin; Yoshida, Kenichiro

    2013-01-01

    The level-truncation analysis of open string field theory for a class of periodic marginal deformations indicates that a branch of solutions in Siegel gauge exists only for a finite range of values of the marginal field. The periodicity in the deformation parameter is thus obscure. We use the relation between gauge-invariant observables and the closed string tadpole on a disk conjectured by Ellwood to construct a map between the deformation parameter of the boundary conformal field theory and the parameter labeling classical solutions of open string field theory. We evaluate the gauge-invariant observables for the numerical solutions in Siegel gauge up to level 12 and find that our results qualitatively agree with the analysis by Sen using the energy-momentum tensor and are consistent with the picture that the finite range of the branch covers one fundamental domain of the periodic moduli space.

  14. Subsidence in the Parícutin lava field: Causes and implications for interpretation of deformation fields at volcanoes

    NASA Astrophysics Data System (ADS)

    Chaussard, Estelle

    2016-06-01

    Assessment of volcanic hazards includes interpretation of ground deformation signal, which, at polygenetic volcanoes often results from the superposition of deformation due to pressure changes in the magmatic system and due to surficial processes such as cooling of emplaced lava. The deformation signal associated with emplaced lava is sometimes considered negligible if fields are decades old, but if the lava thickness is great, deformation may still be occurring, possibly leading to misinterpretation of the observed deformation. Here I evaluate the 2007-2011 ground motion of the 1943-1952 lava field of the Parícutin monogenetic cinder cone, Mexico. Interferometric Synthetic Aperture Radar (InSAR) time series reveal patchy subsidence restricted to the lava field and following linear rates up to 5.5 cm/year. There is a clear correlation between subsidence rates and topography suggesting a causal relationship with deposits or lava thickness. I estimate these thicknesses in the subsiding areas using pre- and post-eruption topographic maps and show that they reach up to 200 m. A numerical model for lava flow cooling was developed considering radiation and convection from the surface, conductive transfer inside the flow and to the ground, and vesiculation and latent heat generation at the top and bottom of the flow. The model shows that compaction induced by cooling of the thick deposits emplaced 60 years ago explains the observed subsidence when conductive transfer to the ground is considered. These results demonstrate that thick deposits can keep deforming significantly even decades after their emplacement, emphasizing the importance of considering cooling processes when interpreting deformation fields at polygenetic volcanoes producing massive lava fields.

  15. Deformities of chironomid larvae and heavy metal pollution: from laboratory to field studies.

    PubMed

    Di Veroli, A; Santoro, F; Pallottini, M; Selvaggi, R; Scardazza, F; Cappelletti, D; Goretti, E

    2014-10-01

    Mouthpart deformities of Chironomus riparius larvae (Diptera) have been investigated to evaluate the toxic effects of contamination by heavy metals in the Genna Stream (Central Italy), situated in an area subjected to intensive swine farms (40000 heads). The livestock farming (fertirrigation) contributes to metal pollution of the Genna Stream with an increase of copper, zinc, cadmium, chromium and nickel in the sediments of the downstream stations. The incidence of mentum deformities was very high at all sampling stations, about 56%. The highest values of deformities were found in the intermediate river reach (St. 3: 65%) and in March (66%), mainly due to an increase in severe deformities. The high incidence of severe deformities (30%) is attributed to the high pollution level by heavy metals in the sediments, in particular to copper and zinc, which showed the highest average value at St. 3 and in March. This field study reflected the relationships between sediment metal concentrations and chironomid mouthpart deformities, previously observed in laboratory tests, and highlighted these deformities as toxicity endpoints. This feature paves the way for their use as an effective tool in freshwater bioassessment monitoring programs to evaluate the toxic effects of metal contamination in freshwater ecosystems.

  16. Ion adsorption and its influence on direct current electric field induced deformations of flexoelectric nematic layers

    NASA Astrophysics Data System (ADS)

    Derfel, Grzegorz; Buczkowska, Mariola

    2011-07-01

    The influence of ion adsorption on the behavior of the nematic liquid crystal layers is studied numerically. The homeotropic flexoelectric layer subjected to the dc electric field is considered. Selective adsorption of positive ions is assumed. The analysis is based on the free energy formalism for ion adsorption. The distributions of director orientation angle, electric potential, and ion concentrations are calculated by numerical resolving of suitable torques equations and Poisson equation. The threshold voltages for the deformations are also determined. It was shown that adsorption affects the distributions of both cations and anions. Sufficiently large number of adsorbed ions leads to spontaneous deformation arising without any threshold if the total number of ions creates sufficiently strong electric field with significant field gradients in the neighborhood of electrodes. The spontaneous deformations are favored by strong flexoelectricity, large thickness, large ion concentrations, weak anchoring, and large adsorption energy.

  17. Brst-Invariant Deformations of Geometric Structures in Topological Field Theories

    NASA Astrophysics Data System (ADS)

    Bytsenko, A. A.; Chaichian, M.; Tureanu, A.; Williams, F. L.

    2013-06-01

    We study a Lie algebra of formal vector fields Wn with its application to the perturbative deformed holomorphic symplectic structure in the A-model, and a Calabi-Yau manifold with boundaries in the B-model. A relevant concept in the vertex operator algebra and the BRST cohomology is that of the elliptic genera (the one-loop string partition function). We show that the elliptic genera can be written in terms of spectral functions of the hyperbolic three-geometry (which inherits the cohomology structure of BRST-like operator). We show that equivalence classes of deformations are described by a Hochschild cohomology theory of the DG-algebra {A} = (A, Q), Q = \\bar {∂ } + ∂ deform, which is defined to be the cohomology of (-1)n Q + dHoch. Here, \\bar {∂ } is the initial nondeformed BRST operator while ∂deform is the deformed part whose algebra is a Lie algebra of linear vector fields gln. We discuss the identification of the harmonic structure (HT•(X);HΩ•(X)) of affine space X and the group {Ext}Xn({{O}}\\triangle, {{O}}\\triangle ) (the HKR isomorphism), and bulk-boundary deformation pairing.

  18. Phase field crystal study of deformation and plasticity in nanocrystalline materials.

    PubMed

    Stefanovic, Peter; Haataja, Mikko; Provatas, Nikolas

    2009-10-01

    We introduce a modified phase field crystal (MPFC) technique that self-consistently incorporates rapid strain relaxation alongside the usual plastic deformation and multiple crystal orientations featured by the traditional phase field crystal (PFC) technique. Our MPFC formalism can be used to study a host of important phase transformation phenomena in material processing that require rapid strain relaxation. We apply the MPFC model to study elastic and plastic deformations in nanocrystalline materials, focusing on the "reverse" Hall-Petch effect. Finally, we introduce a multigrid algorithm for efficient numerical simulations of the MPFC model.

  19. FROGS (Friends of Granites) report

    NASA Astrophysics Data System (ADS)

    Miller, Calvin

    This VGP News, which is devoted to petrology, is a good one for noting the existence of FROGS. FROGS is, as the name suggests, an informal organization of people whose research relates in one way or another to granitic rocks. Its purpose has been to promote communication among geoscientists with different perspectives and concerns about felsic plutonism. Initially, a major focus was experimental petrology and integration of field-oriented and lab-oriented viewpoints; now that there is the opportunity to communicate with the Eos readership, an obvious additional goal will be to bring together volcanic and plutonic views of felsic magmatism.FROGS first gathered in late 1982 under the guidance of E-an Zen and Pete Toulmin (both at U.S. Geological Survey (USGS), Reston, Va.), who saw a need for greater interaction among those interested in granites and for renewed, focused experimental investigations. They produced two newsletters (which were sent out by direct mail) and organized an informal meeting at the Geological Society of America meeting at Indianapolis, Ind., and then turned over the FROG reins to Sue Kieffer (USGS, Flagstaff, Ariz.) and John Clemens (Arizona State University, Tempe). They generated another newsletter, which was directly mailed to a readership that had grown beyond 200.

  20. Nonlinear deformation of a ferrofluid droplet in a uniform magnetic field.

    PubMed

    Zhu, Gui-Ping; Nguyen, Nam-Trung; Ramanujan, R V; Huang, Xiao-Yang

    2011-12-20

    This paper reports experimental and numerical results of the deformation of a ferrofluid droplet on a superhydrophobic surface under the effect of a uniform magnetic field. A water-based ferrofluid droplet surrounded by immiscible mineral oil was stretched by a magnetic field parallel to the substrate surface. The results show that an increasing flux density increases the droplet width and decreases the droplet height. A numerical model was established to study the equilibrium shape of the ferrofluid droplet. The governing equations for physical fields, including the magnetic field, are solved by the finite volume method. The interface between the two immiscible liquids was tracked by the level-set method. Nonlinear magnetization was implemented in the model. Comparison between experimental and numerical results shows that the numerical model can predict well the nonlinear deformation of a ferrofluid droplet in a uniform magnetic field.

  1. Auditory Evoked Potentials from the Frog Eighth Nerve

    DTIC Science & Technology

    1989-09-01

    ACCESSION NO. Brooks AFB, TX 78235-5301 62202F 7757 01 85 11. TITLE (I nclude Security Classification) (U) Auditory Evoked Potentials from the Frog Eighth...identify by block number) S FIELD jGROUP SUB-GROUP F6 07 Auditory Evoked Potential Eighth Nerve Frog 06 10 19. ABSTRACT (Continue on reverse if necessary...and identify by block number) A method for recording evoked potentials from the eighth nerve of frogs using midline and lateral electrodes is described

  2. Molecular structure-dependent deformations in boron nitride nanostructures subject to an electrical field

    NASA Astrophysics Data System (ADS)

    Zhang, Jin; Wang, Chengyuan; Adhikari, Sondipon

    2013-06-01

    Based on a molecular mechanics approach pre-buckling and buckling deformations are studied for boron nitride nanotubes (BNNTs) and nanosheets (BNNSs) subject to an electrical field. Due to the reverse piezoelectric effect a compressive or shear force is generated for those of zigzag and armchair structures, respectively. As a result, axial deformation and buckling occur for zigzag BNNTs and BNNSs, while a torsional or shear deformation occurs for their armchair counterparts, followed by the corresponding buckling. The critical buckling electrical field is also studied and found to decrease as the aspect ratio of BNNTs and BNNSs increases. Such an effect of the aspect ratio turns out to be more pronounced for the buckling of armchair BNNTs and BNNSs.

  3. Investigation on Transient Oscillation of Droplet Deformation before Conical Breakup under Alternating Current Electric Field.

    PubMed

    Yan, Haipeng; He, Limin; Luo, Xiaoming; Wang, Jing; Huang, Xin; Lü, Yuling; Yang, Donghai

    2015-08-04

    In this paper, the conical breakup of a water droplet suspended in oil under the alternating current (ac) electric field was experimentally studied with the help of a high-speed video camera. We observed three stages of transient oscillation of deformation characterized by deformation degree l* before the conical breakup that were described in detail. Then a theoretical model was developed to find out the dynamic mechanisms of that behavior. Despite a very small discrepancy, good agreement between model predictions and experimental observations of the evolution of the droplet deformation was observed, and the possible reasons for the discrepancy were discussed as well. Finally, the stresses on the interface were calculated with the theoretical model and their influence on the dynamic behavior before the breakup was obtained. The differences between the droplet breakup mode of ac and direct current electric field are also discussed in our paper.

  4. High-temperature tensile deformation behavior of aluminum oxide with and without an applied electric field

    NASA Astrophysics Data System (ADS)

    Campbell, James

    1998-12-01

    Ceramics are usually considered to be brittle, but under certain conditions some ceramics exhibit a large degree of ductility. They are fine-grained and exhibit superplastic behavior when deformed at high temperatures and low stresses. Whereas superplasticity gives enhanced ductility to metals, it may be the only method for imparting large plasticity to ceramics. Electric fields have been shown to increase ductility, reduce flow stress and reduce cavitation in the superplastic forming of 7475 Al and yttria-stabilized zirconia. Thus, the concurrent application of an electric field may give improved superplastic properties and increased plasticity to a marginally ductile ceramic such as aluminum oxide (alpha-alumina). Fine-grained alumina tensile specimens, formed by dry pressing and sintering a spray-dried powder, were tested in tension at high temperature with and without an electric field of 300 V/cm. Constant strain rate, strain rate cycling and stress relaxation tests were performed. The effects of an electric field on the ductility, flow stress, cavitation and parameters of the Weertman-Dorn deformation equation were measured. Without an electric field, the following deformation parameters were found: the stress exponent n = 2.2, the grain size exponent p = 1.9, the activation energy Q = 490 kJ/mol and the threshold stress sigmao ≈ 0 MPa, indicating structural superplasticity where grain boundary sliding is the predominant deformation mode and was likely accommodated by the motion of grain boundary dislocations. An electric field of 300 V/cm gave a Joule heating temperature increase of ˜30°C and caused the alumina to swell 5--25% (increasing with time), even while under no applied stress, thereby reducing its ductility and flow stress. After correcting for Joule heating and swelling there was still a significant flow stress reduction produced by the field and the following deformation parameters were found: n = 2.2, p = 1.9, Q = 950 kJ/mol and sigmao ≈ 0

  5. Comparing Calculations of Far-Field Coseismic Deformation

    NASA Astrophysics Data System (ADS)

    Freymueller, J. T.; Dong, J.; Sun, W.

    2014-12-01

    Coseismic displacements from the largest earthquakes are easily detected in geodetic time series over a large area, up to a few thousand km from the fault. For example, detectable displacements from the 2004 Sumatra-Andaman earthquake were reported as far away as Korea, and detectable displacements from the 2011 Tohoku earthquake were reported as far away as Ulaanbaatar, Mongolia. The great reach of these events means that they can distort geodetic coordinates on a global scale, they impact the ability of users to access the reference frame. Point source (Centroid Moment Tensor) and finite fault models for large events are routinely available from purely seismological data (or potentially from local geodetic data), so it is worthwhile to know hwo well we can predict coseismic displacements at GPS sites from independent or quasi-independent data. Ultimately, a suite of geophysical models based on seismic or near-field geodetic data could provide estimates of far-field displacements and uncertainties that may be used for detection of subtle offsets in geodetic time series, and for correction of global coordinates. Slip models based only on teleseismic data do not predict displacments well near the earthquake rupture, because teleseismic data do not resolve spatial details of the slip distribution. Farther from the source, coseismic displacements are not so sensitive to the details of the earthquake source model. Different codes for computing displacements for spherical layered Earth models have not been compared carefully before. Here we compare computed displacements using the method of Pollitz (1996) and the method of Sun et al. (2009) and Sun and Dong (2013). These codes are semi-analytical, so results are sensitive to the number of terms summed for computing Greens functions. We also compare the impact of different Earth models, including PREM, modified versions of PREM, ak135f, and a homogeneous sphere. Our preliminary assessment is that the choice of Earth

  6. Extended sigma-model in nontrivially deformed field-antifield formalism

    NASA Astrophysics Data System (ADS)

    Batalin, Igor A.; Lavrov, Peter M.

    2015-08-01

    We propose an action for the extended sigma-models in the most general setting of the kinetic term allowed in the nontrivially deformed field-antifield formalism. We show that the classical motion equations do naturally take their desired canonical form.

  7. Use of digital image correlation to study the local deformation field of paper and paperboard

    Treesearch

    J.M. Considine; C.T. Scott; R. Gleisner; J.Y. Zhu

    2005-01-01

    Digital image correlation was used to measure the full-field deformation of paperboard and handsheet tensile specimens. The correlation technique was able to accurately measure strain in regions 0.6 by 0.6 mm. Results showed the variation of strain to be much larger than has been previously reported. For machine made paperboard tested in the cross-direction, the...

  8. Seismicity and coupled deformation modeling at the Coso Geothermal Field

    NASA Astrophysics Data System (ADS)

    Kaven, J. O.; Hickman, S. H.; Davatzes, N. C.

    2015-12-01

    Micro-seismicity in geothermal reservoirs, in particular in enhanced geothermal systems (EGS), is a beneficial byproduct of injection and production, as it can indicate the generation of high-permeability pathways on either pre-existing or newly generated faults and fractures. The hazard of inducing an earthquake large enough to be felt at the surface, however, is not easily avoided and has led to termination of some EGS projects. To explore the physical processes leading to permeability creation and maintenance in geothermal systems and the physics of induced earthquakes , we investigated the evolution of seismicity and the factors controlling the migration, moment release rate, and timing of seismicity in the Coso Geothermal Field (CGF). We report on seismicity in the CGF that has been relocated with high precision double-difference relocation techniques and simultaneous velocity inversions to understand hydrologic reservoir compartmentalization and the nature of subsurface boundaries to fluid flow. We find that two distinct compartments are present within the CGF, which are divided by an aseismic gap showing a relatively low Vp/Vs ratio, likely indicating lower temperatures or lower pore pressures within the gap than in the adjacent reservoir compartments. Well-located events with Mw> 3.5 tend to map onto reactivated fault structures that were revealed when imaged by the relocated micro-seismicity. We relate the temporal and spatial migration of moment release rate to the injection and production histories in the reservoir by employing a thermo-poro-elastic finite element model that takes into account the compartment boundaries defined by the seismicity. We find that pore pressure effects alone are not responsible for the migration of seismicity and that poro-elastic and thermo-elastic stress changes are needed in addition to fluid pressure effects to account for the observed moment release rates.

  9. Extended depth-of-field microscopy with a high-speed deformable mirror.

    PubMed

    Shain, William J; Vickers, Nicholas A; Goldberg, Bennett B; Bifano, Thomas; Mertz, Jerome

    2017-03-01

    We present a wide-field fluorescence microscopy add-on that provides a fast, light-efficient extended depth-of-field (EDOF) using a deformable mirror with an update rate of 20 kHz. Out-of-focus contributions in the raw EDOF images are suppressed with a deconvolution algorithm derived directly from the microscope 3D optical transfer function. Demonstrations of the benefits of EDOF microscopy are shown with GCaMP-labeled mouse brain tissue.

  10. A novel digital tomosynthesis (DTS) reconstruction method using a deformation field map.

    PubMed

    Ren, Lei; Zhang, Junan; Thongphiew, Danthai; Godfrey, Devon J; Wu, Q Jackie; Zhou, Su-Min; Yin, Fang-Fang

    2008-07-01

    We developed a novel digital tomosynthesis (DTS) reconstruction method using a deformation field map to optimally estimate volumetric information in DTS images. The deformation field map is solved by using prior information, a deformation model, and new projection data. Patients' previous cone-beam CT (CBCT) or planning CT data are used as the prior information, and the new patient volume to be reconstructed is considered as a deformation of the prior patient volume. The deformation field is solved by minimizing bending energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. The new patient DTS volume is then obtained by deforming the prior patient CBCT or CT volume according to the solution to the deformation field. This method is novel because it is the first method to combine deformable registration with limited angle image reconstruction. The method was tested in 2D cases using simulated projections of a Shepp-Logan phantom, liver, and head-and-neck patient data. The accuracy of the reconstruction was evaluated by comparing both organ volume and pixel value differences between DTS and CBCT images. In the Shepp-Logan phantom study, the reconstructed pixel signal-to-noise ratio (PSNR) for the 60 degrees DTS image reached 34.3 dB. In the liver patient study, the relative error of the liver volume reconstructed using 60 degrees projections was 3.4%. The reconstructed PSNR for the 60 degrees DTS image reached 23.5 dB. In the head-and-neck patient study, the new method using 60 degrees projections was able to reconstruct the 8.1 degrees rotation of the bony structure with 0.0 degrees error. The reconstructed PSNR for the 60 degrees DTS image reached 24.2 dB. In summary, the new reconstruction method can optimally estimate the volumetric information in DTS images using 60 degrees projections. Preliminary validation of the algorithm showed that it is both technically and clinically feasible for image guidance in radiation

  11. Tidal deformability of neutron and hyperon stars within relativistic mean field equations of state

    NASA Astrophysics Data System (ADS)

    Kumar, Bharat; Biswal, S. K.; Patra, S. K.

    2017-01-01

    We systematically study the tidal deformability for neutron and hyperon stars using relativistic mean field equations of state (EOSs). The tidal effect plays an important role during the early part of the evolution of compact binaries. Although, the deformability associated with the EOSs has a small correction, it gives a clean gravitational wave signature in binary inspiral. These are characterized by various Love numbers kl(l =2 ,3 ,4 ), that depend on the EOS of a star for a given mass and radius. The tidal effect of star could be efficiently measured through an advanced LIGO detector from the final stages of an inspiraling binary neutron star merger.

  12. Deformation and burst of a liquid droplet freely suspended in a linear shear field

    NASA Technical Reports Server (NTRS)

    Barthes-Biesel, D.; Acrivos, A.

    1973-01-01

    A theoretical method is presented for predicting the deformation and the conditions for breakup of a liquid droplet freely suspended in a general linear shear field. This is achieved by expanding the solution to the creeping-flow equations in powers of the deformation parameter epsilon and using linear stability theory to determine the onset of bursting. When compared with numerical solutions and with the available experimental data, the theoretical results are generally found to be of acceptable accuracy although, in some cases, the agreement is only qualitative.

  13. Analysis of the induced seismicity of the Lacq gas field (Southwestern France) and model of deformation

    NASA Astrophysics Data System (ADS)

    Bardainne, T.; Dubos-Sallée, N.; Sénéchal, G.; Gaillot, P.; Perroud, H.

    2008-03-01

    The goal of this paper is to propose a model of deformation pattern for the Lacq gas field (southwest of France), considering the temporal and spatial evolution of the observed induced seismicity. This model of deformation has been determined from an updating of the earthquake locations and considering theoretical and analogue models usually accepted for hydrocarbon field deformation. The Lacq seismicity is clearly not linked to the natural seismicity of the Pyrenean range recorded 30km farther to the south since the first event was felt in 1969, after the beginning of the hydrocarbon recovery. From 1974 to 1997, more than 2000 local events (ML < 4.2) have been recorded by two permanent local seismic networks. Unlike previously published results focusing on limited time lapse studies, our analysis relies on the data from 1974 to 1997. Greater accuracy of the absolute locations have been obtained using a well adapted algorithm of 3-D location, after improvement of the 3-D P-wave velocity model and determination of specific station corrections for different clusters of events. This updated catalogue of seismicity has been interpreted taking into account the structural context of the gas field. The Lacq gas field is an anticlinal reservoir where 3-D seismic and borehole data reveal a pattern of high density of fracturing, mainly oriented WNW-ESE. Seismicity map and vertical cross-sections show that majority of the seismic events (70 per cent) occurred above the gas reservoir. Correlation is also observed between the orientation of the pre-existent faults and the location of the seismic activity. Strong and organized seismicity occurred where fault orientation is consistent with the poroelastic stress perturbation due to the gas recovery. On the contrary, the seismicity is quiescient where isobaths of the reservoir roof are closed to be perpendicular to the faults. These quiescient areas as well as the central seismic part are characterized by a surface subsidence

  14. Observations of phase deformation of monomeric systems in electric fields and subsequent polymerization

    NASA Astrophysics Data System (ADS)

    Bentenitis, Nikolaos; Krause, Sonja

    2001-03-01

    When a droplet from one phase of a phase-separated solution of two immiscible homopolymers is injected in the matrix of the other phase and a homogeneous electric field is applied, the droplet can deform either parallel or perpendicular to the electric field direction. In this work one or the other phase consisted of a monomer, which could be polymerized after being distorted in an electric field. DGEBA and Epoxidized Linseed Oil (ELO) were used as monomers along with deionized water and various silicone oils. For example, using DGEBA as the matrix and ELO as the dispersed phase, polymerization of the DGEBA was achieved using a cationic UV-sensitive initiator, that was dissolved only in the DGEBA. In addition, the deformation cycle in 0.1 Hz of deionized water in ELO was observed and compared with theoretical predictions. (Supported by NSF, DMR-9521265)

  15. Coseismic Deformation Field and Fault Slip Distribution of the 2015 Chile Mw8.3 Earthquake

    NASA Astrophysics Data System (ADS)

    Qu, Chunyan; Zuo, Ronghu; Shan, Xin Jian; Zhang, Guohong; Zhang, Yingfeng; Song, Xiaogang

    2016-06-01

    On September 16, 2015, a magnitude 8.3 earthquake struck west of Illapel, Chile. We analyzed Sentinel-1A/IW InSAR data on the descending track acquired before and after the Chile Mw8.3 earthquake of 16 September 2015. We found that the coseismic deformation field of this event consists of many semi circular fringes protruding to east in an approximately 300km long and 190km wide region. The maximum coseismic displacement is about 1.33m in LOS direction corresponding to subsidence or westward shift of the ground. We inverted the coseismic fault slip based on a small-dip single plane fault model in a homogeneous elastic half space. The inverted coseismic slip mainly concentrates at shallow depth above the hypocenter with a symmetry shape. The rupture length along strike is about 340 km with maximum slip of about 8.16m near the trench. The estimated moment is 3.126×1021 N.m (Mw8.27) the maximum depth of coseismic slip near zero appears to 50km. We also analyzed the postseismic deformation fields using four interferograms with different time intervals. The results show that postseismic deformation occurred in a narrow area of approximately 65km wide with maximum slip 11cm, and its predominant motion changes from uplift to subsidence with time. that is to say, at first, the postseismic deformation direction is opposite to that of coseismic deformation, then it tends to be consistent with coseismic deformation.It maybe indicates the differences and changes in the velocity between the Nazca oceanic plate and the South American continental plate.

  16. Extracting a Purely Non-rigid Deformation Field of a Single Structure

    NASA Astrophysics Data System (ADS)

    Demirci, Stefanie; Manstad-Hulaas, Frode; Navab, Nassir

    During endovascular aortic repair (EVAR) treatment, the aortic shape is subject to severe deformation that is imposed by medical instruments such as guide wires, catheters, and the stent graft. The problem definition of deformable registration of images covering the entire abdominal region, however, is highly ill-posed. We present a new method for extracting the deformation of an aneurysmatic aorta. The outline of the procedure includes initial rigid alignment of two abdominal scans, segmentation of abdominal vessel trees, and automatic reduction of their centerline structures to one specified region of interest around the aorta. Our non-rigid registration procedure then only computes local non-rigid deformation and leaves out all remaining global rigid transformations. In order to evaluate our method, experiments for the extraction of aortic deformation fields are conducted on 15 patient datasets from endovascular aortic repair (EVAR) treatment. A visual assessment of the registration results were performed by two vascular surgeons and one interventional radiologist who are all experts in EVAR procedures.

  17. Effects of the Chytrid fungus on the Tarahumara frog (Rana tarahumarae) in Arizona and Sonora, Mexico

    Treesearch

    Stephen F. Hale; Philip C. Rosen; James L. Jarchow; Gregory A. Bradley

    2005-01-01

    We conducted histological analyses on museum specimens collected 1975-1999 from 10 sites in Arizona and Sonora to test for the pathogenic chytrid fungus (Batrachochytrium dendrobatidis) in ranid frogs, focusing on the Tarahumara frog (Rana tarahumarae). During 1981-2000, frogs displaying disease signs were found in the field, and...

  18. Vortex and characteristics of prestrained type-II deformable superconductors under magnetic fields

    NASA Astrophysics Data System (ADS)

    Ma, Zeling; Wang, Xingzhe; Zhou, Youhe

    2016-04-01

    Based on the time-dependent Ginzburg-Landau (TDGL) theory and the linear deformation theory, we present a numerical investigation of magnetic vortex characteristics of a type-II deformable superconductor with prestrain. The effect of prestrain on the wave function, vortex dynamics and energy density of a superconducting film is analyzed by solving the nonlinear TDGL equations in the presence of magnetic field. The results show that the prestrain has a remarkable influence on the magnetic vortex distribution and the vortex dynamics, as well as value of wave function of the superconductor. The different prestrains, i.e., pre-given compression and tension strains, result in dissimilar characteristics on a half-plane of deformable superconductor in an applied magnetic field, and the vortex distribution and entrance in a two dimensional superconducting film. The studies demonstrated that the compression prestrain may speed up the vortexes entering into the region of the superconducting film and increases the vortex number in comparison with those of free-prestrain case, while the tension prestrain shows the reversal features. The energy density and spectrum in the superconductor are further demonstrated numerically and discussed. The present investigation is an attempt to give insight into the superconductivity and electromagnetic characteristics taking into account the elastic deformation in superconductors.

  19. Deformation of biological cells in the acoustic field of an oscillating bubble.

    PubMed

    Zinin, Pavel V; Allen, John S

    2009-02-01

    In this work we develop a theoretical framework of the interaction of microbubbles with bacteria in the ultrasound field using a shell model of the bacteria, following an approach developed previously [P. V. Zinin, Phys. Rev. E 72, 61907 (2005)]. Within the shell model, the motion of the cell in an ultrasonic field is determined by the motion of three components: the internal viscous fluid, a thin elastic shell, and the surrounding viscous fluid. Several conclusions can be drawn from the modeling of sound interaction with a biological cell: (a) the characteristics of a cell's oscillations in an ultrasonic field are determined both by the elastic properties of the shell the viscosities of all components of the system, (b) for dipole quadrupole oscillations the cell's shell deforms due to a change in the shell area this oscillation depends on the surface area modulus K{A} , (c) the relative change in the area has a maximum at frequency f{K} approximately 1/2pi square root[K{A}(rhoa;{3})] , where a is the cell's radius and rho is its density. It was predicted that deformation of the cell wall at the frequency f{K} is high enough to rupture small bacteria such as E . coli in which the quality factor of natural vibrations is less than 1 (Q<1). For bacteria with high value quality factors (Q>1) , the area deformation has a strong peak near a resonance frequency f{K} however, the value of the deformation near the resonance frequency is not high enough to produce sufficient mechanical effect. The theoretical framework developed in this work can be extended for describing the deformation of a biological cell under any arbitrary, external periodic force including radiation forces unduced by acoustical (acoustical levitation) or optical waves (optical tweezers).

  20. Deformation of biological cells in the acoustic field of an oscillating bubble

    NASA Astrophysics Data System (ADS)

    Zinin, Pavel V.; Allen, John S., III

    2009-02-01

    In this work we develop a theoretical framework of the interaction of microbubbles with bacteria in the ultrasound field using a shell model of the bacteria, following an approach developed previously [P. V. Zinin , Phys. Rev. E 72, 61907 (2005)]. Within the shell model, the motion of the cell in an ultrasonic field is determined by the motion of three components: the internal viscous fluid, a thin elastic shell, and the surrounding viscous fluid. Several conclusions can be drawn from the modeling of sound interaction with a biological cell: (a) the characteristics of a cell’s oscillations in an ultrasonic field are determined both by the elastic properties of the shell the viscosities of all components of the system, (b) for dipole quadrupole oscillations the cell’s shell deforms due to a change in the shell area this oscillation depends on the surface area modulus KA , (c) the relative change in the area has a maximum at frequency fK˜(1)/(2π)KA/(ρa3) , where a is the cell’s radius and ρ is its density. It was predicted that deformation of the cell wall at the frequency fK is high enough to rupture small bacteria such as E . coli in which the quality factor of natural vibrations is less than 1 (Q<1) . For bacteria with high value quality factors (Q>1) , the area deformation has a strong peak near a resonance frequency fK ; however, the value of the deformation near the resonance frequency is not high enough to produce sufficient mechanical effect. The theoretical framework developed in this work can be extended for describing the deformation of a biological cell under any arbitrary, external periodic force including radiation forces unduced by acoustical (acoustical levitation) or optical waves (optical tweezers).

  1. Distortion of magnetic field and magnetic force of a brushless dc motor due to deformed rubber magnet

    NASA Astrophysics Data System (ADS)

    Lee, C. J.; Jang, G. H.

    2008-04-01

    This paper investigates the distortion of magnetic field of a brushless dc (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force is calculated by using the Maxwell stress tensor. When the rubber magnet is globally or locally deformed, the unbalanced magnetic force has the frequencies with the first harmonic and the harmonics of slot number ±1. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry.

  2. Yet More Frogs

    ERIC Educational Resources Information Center

    Shutler, Paul M. E.

    2011-01-01

    Extending a recent paper by Derek Holton, we show how to represent the algorithm for the Frog Problem diagrammatically. This diagrammatic representation suggests a simpler proof of the symmetrical case (equal numbers of frogs of each colour) by allowing the even and odd cases to be treated together. It also provides a proof in the asymmetrical…

  3. Yet More Frogs

    ERIC Educational Resources Information Center

    Shutler, Paul M. E.

    2011-01-01

    Extending a recent paper by Derek Holton, we show how to represent the algorithm for the Frog Problem diagrammatically. This diagrammatic representation suggests a simpler proof of the symmetrical case (equal numbers of frogs of each colour) by allowing the even and odd cases to be treated together. It also provides a proof in the asymmetrical…

  4. Yet more frogs

    NASA Astrophysics Data System (ADS)

    Shutler, Paul M. E.

    2011-06-01

    Extending a recent paper by Derek Holton, we show how to represent the algorithm for the Frog Problem diagrammatically. This diagrammatic representation suggests a simpler proof of the symmetrical case (equal numbers of frogs of each colour) by allowing the even and odd cases to be treated together. It also provides a proof in the asymmetrical case (unequal numbers of frogs) as an extension of the symmetrical case. The issue of whether frogs of a given colour should be allowed to move in either direction is discussed. While it is possible to restrict to the case of movement in a single direction, results for bi-directional movement can be obtained by making the correspondence between the algorithm and its diagrammatic representation more concrete. The Frog Problem then becomes a form of constrained shortest path problem around the diagram, and from this point of view optimality of the algorithm becomes much clearer.

  5. Nanoscale mapping of the three-dimensional deformation field within commercial nanodiamonds

    SciTech Connect

    Maqbool, Muhammad Salman; Hoxley, David; Phillips, Nicholas W.; Coughlan, Hannah D.; Darmanin, Connie; Johnson, Brett C.; Harder, Ross; Clark, Jesse N.; Balaur, Eugeniu; Abbey, Brian

    2017-01-01

    The unique properties of nanodiamonds make them suitable for use in a wide range of applications, including as biomarkers for cellular tracking in vivo at the molecular level. The sustained fluorescence of nanodiamonds containing nitrogen-vacancy (N-V) centres is related to their internal structure and strain state. Theoretical studies predict that the location of the N-V centre and the nanodiamonds' residual elastic strain state have a major influence on their photoluminescence properties. However, to date there have been no direct measurements made of their spatially resolved deformation fields owing to the challenges that such measurements present. Here we apply the recently developed technique of Bragg coherent diffractive imaging (BCDI) to map the three-dimensional deformation field within a single nanodiamond of approximately 0.5 µm diameter. The results indicate that there are high levels of residual elastic strain present in the nanodiamond which could have a critical influence on its optical and electronic properties.

  6. Note: Dynamic meso-scale full field surface deformation measurement of heterogeneous materials

    NASA Astrophysics Data System (ADS)

    Ravindran, S.; Tessema, A.; Kidane, A.

    2016-03-01

    A dynamic experiment at mesoscale is developed to measure local deformation and strain in granular materials at high temporal and spatial resolutions. The experimental setup is comprised of a high-speed camera along with a high magnification extension tube. The method is demonstrated by measuring the full field strain across and in the boundary of the crystals at a high temporal resolution in polymer bonded sugar crystals and glass beads filled epoxy particulate composite specimens under dynamic loading. In both cases, the local strain heterogeneity is captured successfully. The measured strain and deformation field can be further used to obtain the relative motion of each crystal, crystal rotation, and the relative displacement between the polymer interface and the crystal, which are very critical to understand the local failure mechanisms in heterogeneous materials.

  7. Numerical solutions of open string field theory in marginally deformed backgrounds

    NASA Astrophysics Data System (ADS)

    Kishimoto, Isao; Takahashi, Tomohiko

    2013-09-01

    We investigate numerical solutions of bosonic open string field theory in some marginally deformed backgrounds, which are obtained by expanding the action around an identity-based marginal solution with one parameter. We construct numerical solutions in the Siegel gauge and the Landau gauge corresponding to the tachyon vacuum. Their vacuum energy approximately cancels the D-brane tension for larger intervals of the parameter with increasing truncation level. The result is consistent with the previous expectation that the identity-based marginal solution has vanishing energy regardless of the values of the parameter. We also study the marginal branch (M-branch) and the vacuum branch (V-branch) and evaluate not only the vacuum energy but also the gauge invariant overlaps with the graviton and the closed tachyon. We observe that there is a finite bound for the value of the massless field of numerical solutions even in the marginally deformed background.

  8. Predation by Oregon spotted frogs (Rana pretiosa) on Western toads (Bufo boreas) in Oregon, USA

    USGS Publications Warehouse

    Pearl, Christopher A.; Hayes, M.P.

    2002-01-01

    Toads of the genus Bufo co-occur with true frogs (family Ranidae) throughout their North American ranges. Yet, Bufo are rarely reported as prey for ranid frogs, perhaps due to dermal toxins that afford them protection from some predators. We report field observations from four different localities demonstrating that Oregon spotted frogs (Rana pretiosa) readily consume juvenile western toads (Bufo boreas) at breeding sites in Oregon. Unpalatability thought to deter predators of selected taxa and feeding mode may not protect juvenile stages of western toads from adult Oregon spotted frogs. Activity of juvenile western toads can elicit ambush behavior by Oregon spotted frog adults. Our review of published literature suggests that regular consumption of toadlets sets Oregon spotted frogs apart from most North American ranid frogs. Importance of the trophic context of juvenile western toads as a seasonally important resource to Oregon spotted frogs needs critical investigation.

  9. Improved Automatic Detection of New T2 Lesions in Multiple Sclerosis Using Deformation Fields.

    PubMed

    Cabezas, M; Corral, J F; Oliver, A; Díez, Y; Tintoré, M; Auger, C; Montalban, X; Lladó, M; Pareto, D; Rovira, À

    2016-06-09

    Detection of disease activity, defined as new/enlarging T2 lesions on brain MR imaging, has been proposed as a biomarker in MS. However, detection of new/enlarging T2 lesions can be hindered by several factors that can be overcome with image subtraction. The purpose of this study was to improve automated detection of new T2 lesions and reduce user interaction to eliminate inter- and intraobserver variability. Multiparametric brain MR imaging was performed at 2 time points in 36 patients with new T2 lesions. Images were registered by using an affine transformation and the Demons algorithm to obtain a deformation field. After affine registration, images were subtracted and a threshold was applied to obtain a lesion mask, which was then refined by using the deformation field, intensity, and local information. This pipeline was compared with only applying a threshold, and with a state-of-the-art approach relying only on image intensities. To assess improvements, we compared the results of the different pipelines with the expert visual detection. The multichannel pipeline based on the deformation field obtained a detection Dice similarity coefficient close to 0.70, with a false-positive detection of 17.8% and a true-positive detection of 70.9%. A statistically significant correlation (r = 0.81, P value = 2.2688e-09) was found between visual detection and automated detection by using our approach. The deformation field-based approach proposed in this study for detecting new/enlarging T2 lesions resulted in significantly fewer false-positives while maintaining most true-positives and showed a good correlation with visual detection annotations. This approach could reduce user interaction and inter- and intraobserver variability. © 2016 American Society of Neuroradiology.

  10. Geodetic Measurements and Numerical Models of Deformation at Coso Geothermal Field, California, USA

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Reinisch, E. C.; Feigl, K. L.; Davatzes, N. C.

    2016-12-01

    We measure transient deformation at the Coso geothermal field in south-central California using interferometric synthetic aperture data acquired between 2004 and 2016 by the Envisat and Sentinel-1A satellite missions. All well-correlated interferometric pairs show subsidence, with rates as high as 30 mm/year, over a large 75 km2 circular area surrounding the field below which most of the seismicity associated with geothermal production is located. The deformation signature remains in the same location throughout the 12 year interval. Time-series analysis of multiple interferometric pairs reveals continuous subsidence. A decrease in the subsidence rate after 2010 corresponds to a decrease in the net production rate. Using three-dimensional, fully numerical, multiphysics models, we explore the coupling between deformation and geothermal production. We seek to distinguish between two possible mechanisms: (i) decreasing pore-pressure following net extraction of fluids, or (ii) decrease in temperature of presumably fractured reservoir rock. Irrespective of the mechanism, a contracting ellipsoidal reservoir located at a depth of 2 km, with a volume of 80 km3 or less is required to explain the geodetic observations. Almost 90% of the seismicity beneath the field occurs within this 80 km3 ellipsoid.

  11. Effects of topography on the interpretation of the deformation field of prominent volcanoes - Application to Etna

    USGS Publications Warehouse

    Cayol, V.; Cornet, F.H.

    1998-01-01

    We have investigated the effects of topography on the surface-deformation field of volcanoes. Our study provides limits to the use of classical half-space models. Considering axisymmetrical volcanoes, we show that interpreting ground-surface displacements with half-space models can lead to erroneous estimations of the shape of the deformation source. When the average slope of the flanks of a volcano exceeds 20??, tilting in the summit area is reversed to that expected for a flat surface. Thus, neglecting topography may lead to misinterpreting an inflation of the source as a deflation. Comparisons of Mogi's model with a three-dimensional model shows that ignoring topography may lead to an overestimate of the source-volume change by as much as 50% for a slope of 30??. This comparison also shows that the depths calculated by using Mogi's solution for prominent volcanoes should be considered as depths from the summit of the edifices. Finally, we illustrate these topographic effects by analyzing the deformation field measured by radar interferometry at Mount Etna during its 1991-1993 eruption. A three-dimensional modeling calculation shows that the flattening of the deflation field near the volcano's summit is probably a topographic effect.

  12. Crustal Deformation Field Around Rift Zone In Southeastern Afar Derived From Jers-1/in-sar

    NASA Astrophysics Data System (ADS)

    Ozawa, T.; Nogi, Y.; Shibuya, K.

    Afar is one of the major active rift zones recognized on the ground and located around the triple junction of Arabia, Somalia and Nubian plates. Afar is one of the major rift zones recognized on the ground. The crustal deformation of Afar has been deduced from paleomagnetism, geology and seismology by many scientists. The current crustal deformation must be detected by geodetic measurements. Ruegg et al. (J. Geophys. Res., 1984) showed the crustal deformation across the Asal-Ghoubbet rift with rate of about 60 mm/yr extension derived from triangulation and trilateration. Walpersdorf et al. (J. Geodyn., 1999) show the opening between South Djibouti and Yemen with rate of 16 mm/yr by GPS surveys. Denser observations are required for detailed crustal deformation, however it is difficult to construct such observation network because of harsh environment. The geodetic application of remote sensing is useful in this region, and we apply JERS-1 SAR interferometry in southeastern Afar, which is one of the most active deformation area. In this study, we use six SAR scenes observed from 1996/5/20 to 1997/5/7, and generate five interferograms; these repeat cycles are 88 (2 pairs), 176, 264, 352 days. First, we generate the digital elevation model (DEM) from two 88 repeat cycle pairs applying the multiple pass SAR interferometry method by Kwok and Fahnestock (IEEE Trans. Geosci. Remote Sensing, 1996). Next, the topographic fringes of all pairs are removed using the DEM. The crustal deformation derived from SAR interferometry increases with expanding repeat cycle. Finally, the velocity field is estimated by fitting to linear trend for each pixel. The spreading rate of Asal-Ghoubbet rift derived from SAR interferometry is good agreement with that by Ruegg et al. (J. Geophys. Res., 1984). We can see the crustal deformation with the subsidence sense in the west of Asal-Ghoubbet rift. This suggests that the extension is distinguished in this area. The subsidence sense deformation

  13. Strain localization in carbonate rocks experimentally deformed in the ductile field

    NASA Astrophysics Data System (ADS)

    Rybacki, E.; Morales, L. F. G.; Dresen, G.

    2012-04-01

    The deformation of rocks in the Earth's crust is often localized, varying from brittle fault gauges in shallow environments to mylonites in ductile shear zones at greater depth. A number of theoretical, experimental, and field studies focused on the evolution and extend of brittle fault zones, but little is known so far about initiation of ductile shear zones. Strain localization in rocks deforming at high temperature and pressure may be induced by several physical, chemical, or structurally-related mechanisms. We performed simple and pure shear deformation experiments on carbonate rocks containing structural inhomogenities in the ductile deformation regime. The results may help to gain insight into the evolution of high temperature shear zones. As starting material we used cylindrical samples of coarse-grained Carrara marble containing one or two 1 mm thin artificially prepared sheets of fine-grained Solnhofen limestone, which act as soft inclusions under the applied experimental conditions. Length and diameter of the investigated solid and hollow cylinders were 10-20 mm and 10-15 mm, respectively. Samples were deformed in a Paterson-type gas deformation apparatus at 900° C temperature and confining pressures of 300 and 400 MPa. Three samples were deformed in axial compression at a bulk strain rate of 8x10-5 s-1to axial strains between 0.02 and 0.21 and 15 samples were twisted in torsion at a bulk shear strain rate of 2x10-4 s-1 to shear strains between 0.01 and 3.74. At low strain, specimens deformed axially and in torsion show minor strain hardening that is replaced by strain weakening at shear strains in excess of about 0.2. Peak shear stress at the imposed condition is about 20 MPa. Strain localized strongly within the weak inclusions as indicated by inhomogeneous bending of initially straight strain markers on sample jackets. Maximum strain concentration within inclusions with respect to the adjacent matrix was between 4 and 40, depending on total strain and

  14. A statistical analysis of the elastic distortion and dislocation density fields in deformed crystals

    NASA Astrophysics Data System (ADS)

    Mohamed, Mamdouh S.; Larson, Bennett C.; Tischler, Jonathan Z.; El-Azab, Anter

    2015-09-01

    The statistical properties of the elastic distortion fields of dislocations in deforming crystals are investigated using the method of discrete dislocation dynamics to simulate dislocation structures and dislocation density evolution under tensile loading. Probability distribution functions (PDF) and pair correlation functions (PCF) of the simulated internal elastic strains and lattice rotations are generated for tensile strain levels up to 0.85%. The PDFs of simulated lattice rotation are compared with sub-micrometer resolution three-dimensional X-ray microscopy measurements of rotation magnitudes and deformation length scales in 1.0% and 2.3% compression strained Cu single crystals to explore the linkage between experiment and the theoretical analysis. The statistical properties of the deformation simulations are analyzed through determinations of the Nye and Kröner dislocation density tensors. The significance of the magnitudes and the length scales of the elastic strain and the rotation parts of dislocation density tensors are demonstrated, and their relevance to understanding the fundamental aspects of deformation is discussed.

  15. A statistical analysis of the elastic distortion and dislocation density fields in deformed crystals

    DOE PAGES

    Mohamed, Mamdouh S.; Larson, Bennett C.; Tischler, Jonathan Z.; ...

    2015-05-18

    The statistical properties of the elastic distortion fields of dislocations in deforming crystals are investigated using the method of discrete dislocation dynamics to simulate dislocation structures and dislocation density evolution under tensile loading. Probability distribution functions (PDF) and pair correlation functions (PCF) of the simulated internal elastic strains and lattice rotations are generated for tensile strain levels up to 0.85%. The PDFs of simulated lattice rotation are compared with sub-micrometer resolution three-dimensional X-ray microscopy measurements of rotation magnitudes and deformation length scales in 1.0% and 2.3% compression strained Cu single crystals to explore the linkage between experiment and the theoreticalmore » analysis. The statistical properties of the deformation simulations are analyzed through determinations of the Nye and Kr ner dislocation density tensors. The significance of the magnitudes and the length scales of the elastic strain and the rotation parts of dislocation density tensors are demonstrated, and their relevance to understanding the fundamental aspects of deformation is discussed.« less

  16. Strain and deformations engineered germanene bilayer double gate-field effect transistor by first principles

    NASA Astrophysics Data System (ADS)

    Meher Abhinav, E.; Chandrasekaran, Gopalakrishnan; Kasmir Raja, S. V.

    2017-10-01

    Germanene, silicene, stanene, phosphorene and graphene are some of single atomic materials with novel properties. In this paper, we explored bilayer germanene-based Double Gate-Field Effect Transistor (DG-FET) with various strains and deformations using Density Functional Theory (DFT) and Green's approach by first-principle calculations. The DG-FET of 1.6 nm width, 6 nm channel length (Lch) and HfO2 as gate dielectric has been modeled. For intrinsic deformation of germanene bilayer, we have enforced minute mechanical deformation of wrap and twist (5°) and ripple (0.5 Å) on germanene bilayer channel material. By using NEGF formalism, I-V Characteristics of various strains and deformation tailored DG-FET was calculated. Our results show that rough edge and single vacancy (5-9) in bilayer germanene diminishes the current around 47% and 58% respectively as compared with pristine bilayer germanene. In case of strain tailored bilayer DG-FET, multiple NDR regions were observed which can be utilized in building stable multiple logic states in digital circuits and high frequency oscillators using negative resistive techniques.

  17. A statistical analysis of the elastic distortion and dislocation density fields in deformed crystals

    SciTech Connect

    Mohamed, Mamdouh S.; Larson, Bennett C.; Tischler, Jonathan Z.; El-Azab, Anter

    2015-05-18

    The statistical properties of the elastic distortion fields of dislocations in deforming crystals are investigated using the method of discrete dislocation dynamics to simulate dislocation structures and dislocation density evolution under tensile loading. Probability distribution functions (PDF) and pair correlation functions (PCF) of the simulated internal elastic strains and lattice rotations are generated for tensile strain levels up to 0.85%. The PDFs of simulated lattice rotation are compared with sub-micrometer resolution three-dimensional X-ray microscopy measurements of rotation magnitudes and deformation length scales in 1.0% and 2.3% compression strained Cu single crystals to explore the linkage between experiment and the theoretical analysis. The statistical properties of the deformation simulations are analyzed through determinations of the Nye and Kr ner dislocation density tensors. The significance of the magnitudes and the length scales of the elastic strain and the rotation parts of dislocation density tensors are demonstrated, and their relevance to understanding the fundamental aspects of deformation is discussed.

  18. Complex lung motion estimation via adaptive bilateral filtering of the deformation field.

    PubMed

    Papiez, Bartlomiej W; Heinrich, Mattias Paul; Risser, Laurent; Schnabel, Julia A

    2013-01-01

    Estimation of physiologically plausible deformations is critical for several medical applications. For example, lung cancer diagnosis and treatment requires accurate image registration which preserves sliding motion in the pleural cavity, and the rigidity of chest bones. This paper addresses these challenges by introducing a novel approach for regularisation of non-linear transformations derived from a bilateral filter. For this purpose, the classic Gaussian kernel is replaced by a new kernel that smoothes the estimated deformation field with respect to the spatial position, intensity and deformation dissimilarity. The proposed regularisation is a spatially adaptive filter that is able to preserve discontinuity between the lungs and the pleura and reduces any rigid structures deformations in volumes. Moreover, the presented framework is fully automatic and no prior knowledge of the underlying anatomy is required. The performance of our novel regularisation technique is demonstrated on phantom data for a proof of concept as well as 3D inhale and exhale pairs of clinical CT lung volumes. The results of the quantitative evaluation exhibit a significant improvement when compared to the corresponding state-of-the-art method using classic Gaussian smoothing.

  19. Deformation analysis of vesicles in an alternating-current electric field

    NASA Astrophysics Data System (ADS)

    Tang, Yu-Gang; Liu, Ying; Feng, Xi-Qiao

    2014-08-01

    In this paper the shape equation for axisymmetric vesicles subjected to an ac electric field is derived on the basis of the liquid-crystal model. The equilibrium morphology of a lipid vesicle is determined by the minimization of its free energy in coupled mechanical and ac electric fields. Besides elastic bending, the effects of the osmotic pressure difference, surface tension, Maxwell pressure, and flexoelectric and dielectric properties of phospholipid membrane as well are taken into account. The influences of elastic bending, osmotic pressure difference, and surface tension on the frequency-dependent behavior of a vesicle membrane in an ac electric field are examined. The singularity of the ac electric field is also investigated. Our theoretical results of vesicle deformation agree well with previous experimental and numerical results. The present study provides insights into the physical mechanisms underpinning the frequency-dependent morphological evolution of vesicles in the electric and mechanical fields.

  20. Deformation of a nearly hemispherical conducting drop due to an electric field: Theory and experiment

    NASA Astrophysics Data System (ADS)

    Corson, L. T.; Tsakonas, C.; Duffy, B. R.; Mottram, N. J.; Sage, I. C.; Brown, C. V.; Wilson, S. K.

    2014-12-01

    We consider, both theoretically and experimentally, the deformation due to an electric field of a pinned nearly hemispherical static sessile drop of an ionic fluid with a high conductivity resting on the lower substrate of a parallel-plate capacitor. Using both numerical and asymptotic approaches, we find solutions to the coupled electrostatic and augmented Young-Laplace equations which agree very well with the experimental results. Our asymptotic solution for the drop interface extends previous work in two ways, namely, to drops that have zero-field contact angles that are not exactly π/2 and to higher order in the applied electric field, and provides useful predictive equations for the changes in the height, contact angle, and pressure as functions of the zero-field contact angle, drop radius, surface tension, and applied electric field. The asymptotic solution requires some numerical computations, and so a surprisingly accurate approximate analytical asymptotic solution is also obtained.

  1. Deforming the theory λϕ4 along the parameters and fields gradient flows

    NASA Astrophysics Data System (ADS)

    Cartas-Fuentevilla, R.; Olvera-Santamaria, A.

    2015-01-01

    Considering the action for the theory λϕ4 for a massive scalar bosonic field as an entropy functional on the space of coupling constants and on the space of fields, we determine the gradient flows for the scalar field, the mass and the self-interaction parameter. When the flow parameter is identified with the energy scale, we show that there exist phase transitions between unbroken exact symmetry scenarios and spontaneous symmetry breaking scenarios at increasingly high energies. Since a nonlinear heat equation drives the scalar field through a reaction-diffusion process, in general the flows are not reversible, mimicking the renormalization group flows of the c-theorem; the deformation of the field at increasingly high energies can be described as nonlinear traveling waves, or solitons associated to self-similar solutions.

  2. Deformation analysis of vesicles in an alternating-current electric field.

    PubMed

    Tang, Yu-Gang; Liu, Ying; Feng, Xi-Qiao

    2014-08-01

    In this paper the shape equation for axisymmetric vesicles subjected to an ac electric field is derived on the basis of the liquid-crystal model. The equilibrium morphology of a lipid vesicle is determined by the minimization of its free energy in coupled mechanical and ac electric fields. Besides elastic bending, the effects of the osmotic pressure difference, surface tension, Maxwell pressure, and flexoelectric and dielectric properties of phospholipid membrane as well are taken into account. The influences of elastic bending, osmotic pressure difference, and surface tension on the frequency-dependent behavior of a vesicle membrane in an ac electric field are examined. The singularity of the ac electric field is also investigated. Our theoretical results of vesicle deformation agree well with previous experimental and numerical results. The present study provides insights into the physical mechanisms underpinning the frequency-dependent morphological evolution of vesicles in the electric and mechanical fields.

  3. Deformed SW curve and the null vector decoupling equation in Toda field theory

    NASA Astrophysics Data System (ADS)

    Poghossian, Rubik

    2016-04-01

    It is shown that the deformed Seiberg-Witten curve equation after Fourier transform is mapped into a differential equation for the AGT dual 2d CFT cnformal block containing an extra completely degenerate field. We carefully match parameters in two sides of duality thus providing not only a simple independent prove of the AGT correspondence in Nekrasov-Shatashvili limit, but also an extension of AGT to the case when a secondary field is included in the CFT conformal block. Implications of our results in the study of monodromy problems for a large class of n'th order Fuchsian differential equations are discussed.

  4. A high-order finite deformation phase-field approach to fracture

    NASA Astrophysics Data System (ADS)

    Weinberg, Kerstin; Hesch, Christian

    2017-07-01

    Phase-field approaches to fracture allow for convenient and efficient simulation of complex fracture pattern. In this paper, two variational formulations of phase-field fracture, a common second-order model and a new fourth-order model, are combined with a finite deformation ansatz for general nonlinear materials. The material model is based on a multiplicative decomposition of the principal stretches in a tensile and a compressive part. The excellent performance of the new approach is illustrated in classical numerical examples.

  5. Sine-square deformation of solvable spin chains and conformal field theories

    NASA Astrophysics Data System (ADS)

    Katsura, Hosho

    2012-03-01

    We study solvable spin chains, one-dimensional massless Dirac fermions and conformal field theories (CFTs) with sine-square deformation (SSD), in which the Hamiltonian density is modulated by the function f(x) = sin 2(πx/ℓ), where x is the position and ℓ is the length of the system. For the XY chain and the transverse field Ising chain at criticality, it is shown that the ground state of an open system with SSD is identical to that of a uniform chain with periodic boundary conditions. The same holds for the massless Dirac fermions with SSD, corresponding to the continuum limit of the gapless XY chain. For general CFTs, we find that the Hamiltonian of a system with SSD has an expression in terms of the generators of the Virasoro algebra. This allows us to show that the vacuum state is an exact eigenstate of the sine-square deformed Hamiltonian. Furthermore, for a restricted class of CFTs associated with affine Lie (Kac-Moody) algebras, including c = 1 Gaussian CFT, we prove that the vacuum is an exact ground state of the deformed Hamiltonian. This explains why the SSD has succeeded in suppressing boundary effects in one-dimensional critical systems, as observed in previous numerical studies.

  6. Getting drowned in a swirl: Deformable bead-spring model microswimmers in external flow fields

    NASA Astrophysics Data System (ADS)

    Küchler, Niklas; Löwen, Hartmut; Menzel, Andreas M.

    2016-02-01

    Deformability is a central feature of many types of microswimmers, e.g., for artificially generated self-propelled droplets. Here, we analyze deformable bead-spring microswimmers in an externally imposed solvent flow field as simple theoretical model systems. We focus on their behavior in a circular swirl flow in two spatial dimensions. Linear (straight) two-bead swimmers are found to circle around the swirl with a slight drift to the outside with increasing activity. In contrast to that, we observe for triangular three-bead or squarelike four-bead swimmers a tendency of being drawn into the swirl and finally getting drowned, although a radial inward component is absent in the flow field. During one cycle around the swirl, the self-propulsion direction of an active triangular or squarelike swimmer remains almost constant, while their orbits become deformed exhibiting an "egglike" shape. Over time, the swirl flow induces slight net rotations of these swimmer types, which leads to net rotations of the egg-shaped orbits. Interestingly, in certain cases, the orbital rotation changes sense when the swimmer approaches the flow singularity. Our predictions can be verified in real-space experiments on artificial microswimmers.

  7. Effective field theory of emergent symmetry breaking in deformed atomic nuclei

    DOE PAGES

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2015-09-03

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of whichmore » serves as band head of a rotational band.« less

  8. Effective field theory of emergent symmetry breaking in deformed atomic nuclei

    SciTech Connect

    Papenbrock, Thomas F.; Weidenmüller, H. A.

    2015-09-03

    Spontaneous symmetry breaking in non-relativistic quantum systems has previously been addressed in the framework of effective field theory. Low-lying excitations are constructed from Nambu–Goldstone modes using symmetry arguments only. In this study, we extend that approach to finite systems. The approach is very general. To be specific, however, we consider atomic nuclei with intrinsically deformed ground states. The emergent symmetry breaking in such systems requires the introduction of additional degrees of freedom on top of the Nambu–Goldstone modes. Symmetry arguments suffice to construct the low-lying states of the system. Lastly, in deformed nuclei these are vibrational modes each of which serves as band head of a rotational band.

  9. Measurements of mechanical deformation using a full field optical interferometry and a fast camera

    NASA Astrophysics Data System (ADS)

    Pérez López, Carlos; Mendoza Santoyo, Fernando; Gutiérrez Zamarripa, Rodolfo; Caloca Mendez, Cristian

    2006-02-01

    Full field optical interferometry known as ESPI (Electronic Speckle Pattern Interferometry), has been applied to dynamical deformations on solid and semisolid objects. Although microscopic (1 to 30 micrometers), these deformations offer enough information to know even an early crack detection of the material. In industrial and biomedical environments however there is a lot of noise bigger than the signal we try to recovery, therefore is necessary to compensate mechanical or digitally or both. In this paper we will discuss the basic operating principle of the interferometer and analyze its performance. The technique use a continue wave laser for illuminating the tested object. The transient event is recorded by an ultra fast digital image camera. Data processing is completed with a help of a spatio-temporal algorithm. Some results are presented.

  10. Rhyolite domes in the Krafla area, North Iceland. Densities and deformation fields

    NASA Astrophysics Data System (ADS)

    Agustsdottir, T.; Einarsson, P.; Gudmundsson, M. T.

    2009-12-01

    Krafla is a central volcano in the Northern Volcanic Zone (NVZ) of Iceland. It began forming about 200 000 years BP, has a caldera, and is transected by a N10°A trending fissure swarm. Krafla’s products are mostly basaltic but rhyolite domes have formed around the caldera rims. Krafla’s products were mostly erupted during the last glacial period, 110 000 years BP to 10 000 years BP. Silicic rocks in Iceland are generally associated with central volcanoes and are often emplaced on or around caldera rims. Rhyolite magma can rise, due to buoyancy forces and either form a cryptodome in the shallow crust or rise to the surface, where it erupts. Due to its high viscosity and resistance to flow it often accumulates and forms a lava dome over the vent. A gravity survey was carried out in the area of Krafla in 2007 and 2008 to determine the mean bulk density values of rhyolite domes. Data on density and volumes is essential for meaningful modelling of the emplacement of cryptodomes and lava domes. Such data are scarce. Profiles were measured over three formations, ranging in size from Hlidarfjall (310 m high and 2 km long), formed under ice 90 000 years BP, to Hrafntinnuhryggur (80 m high and 2,5 km long) formed 24 000 years BP under a glacier to Hraunbunga (125 m high and 1,8 km long) formed 10 000 years BP. Mean bulk density for each formation was obtained by the Nettleton method. The results are that all the domes have low densities, reflecting both low grain-density and high porosity. The domes’s density values are significantly smaller than those of the surroundings, creating a density contrast possibly sufficient to drive the ascent of rhyolite magma. Furthermore, results from gravity data demonstrate that these formations are neither buried by younger volcanic eruptives nor are any roots detected. The domes studied were therefore emplaced as vent-forming domes. Additionally, we propose a model to describe the deformation field above a rising batch of magma

  11. Investigation of flow and solute transport at the field scale through heterogeneous deformable porous media

    NASA Astrophysics Data System (ADS)

    Chang, Ching-Min; Yeh, Hund-Der

    2016-09-01

    This work describes an investigation of the spatial statistical structure of specific discharge field and solute transport process of a nonreactive solute at the field scale through a heterogeneous deformable porous medium. The flow field is driven by a vertical gradient in the excess pore water pressure induced by a step increase in load applied on the upper part of a finite-thickness aquifer. The non-stationary spectral representation is adopted to characterize the spatial covariance of the specific discharge field necessary for the development of the solute particle trajectory statistics using the Lagrangian formalism. We show that the statistics of the specific discharge and particle trajectory derived herein are non-stationary and functions of the coefficient of soil compressibility, μ. The effect of μ on the relative variation of specific discharge and the solute particle trajectory statistics are analyzed upon evaluating our expressions.

  12. Experience with wavefront sensor and deformable mirror interfaces for wide-field adaptive optics systems

    NASA Astrophysics Data System (ADS)

    Basden, A. G.; Atkinson, D.; Bharmal, N. A.; Bitenc, U.; Brangier, M.; Buey, T.; Butterley, T.; Cano, D.; Chemla, F.; Clark, P.; Cohen, M.; Conan, J.-M.; de Cos, F. J.; Dickson, C.; Dipper, N. A.; Dunlop, C. N.; Feautrier, P.; Fusco, T.; Gach, J. L.; Gendron, E.; Geng, D.; Goodsell, S. J.; Gratadour, D.; Greenaway, A. H.; Guesalaga, A.; Guzman, C. D.; Henry, D.; Holck, D.; Hubert, Z.; Huet, J. M.; Kellerer, A.; Kulcsar, C.; Laporte, P.; Le Roux, B.; Looker, N.; Longmore, A. J.; Marteaud, M.; Martin, O.; Meimon, S.; Morel, C.; Morris, T. J.; Myers, R. M.; Osborn, J.; Perret, D.; Petit, C.; Raynaud, H.; Reeves, A. P.; Rousset, G.; Sanchez Lasheras, F.; Sanchez Rodriguez, M.; Santos, J. D.; Sevin, A.; Sivo, G.; Stadler, E.; Stobie, B.; Talbot, G.; Todd, S.; Vidal, F.; Younger, E. J.

    2016-06-01

    Recent advances in adaptive optics (AO) have led to the implementation of wide field-of-view AO systems. A number of wide-field AO systems are also planned for the forthcoming Extremely Large Telescopes. Such systems have multiple wavefront sensors of different types, and usually multiple deformable mirrors (DMs). Here, we report on our experience integrating cameras and DMs with the real-time control systems of two wide-field AO systems. These are CANARY, which has been operating on-sky since 2010, and DRAGON, which is a laboratory AO real-time demonstrator instrument. We detail the issues and difficulties that arose, along with the solutions we developed. We also provide recommendations for consideration when developing future wide-field AO systems.

  13. The effects of gallamine on field and dorsal root potentials produced by antidromic stimulation of motor fibres in the frog spinal cord.

    PubMed

    Galindo, J; Rudomin, P

    1978-05-12

    The effects of gallamine on the intraspinal field potentials and the dorsal root potentials produced by antidromic stimulation of motor fibres were studied in the isolated frog spinal cord preparation. After gallamine (10-(3) M), the duration of the negative field potential produced by antidromic activation of motoneurons (N1 response) was increased often without changing its amplitude. This resulted in an increased passive spread of the antidromic action potential towards the dorsal dendritic regions, where afferent fibres terminate. In the untreated spinal cord, stimulation of motor axons produced a late negative dorsal root potential (VR-DRP) which was depressed after gallamine administration. Abolition of the VR-DRP was frequently associated with the appearance of a short latency, conducted response, in the dorsal roots (EVR-DRP). The earliest component of the EVR-DRP had a latency ranging between 0.5 and 2.5 ms measured after the peak of the N1 response recorded at the motor nucleus. Such a brief latency of the EVR-DRP suggests that this response results from electrical interaction between motoneurons and afferent fibres. After gallamine, the primary afferent depolarization produced by orthodromic stimulation of sensory nerves facilitates the EVR-DRP without necessarily increasing the amplitude or duration of the N1 response. Also, gallamine appears to increase directly the excitability of the afferent fibre terminal arborizations. The nature of the electrical interaction between motoneuron dendrites and afferent fibre terminal arborizations is discussed in terms of two hypotheses: interaction by current flows and by electrical coupling.

  14. Impact of the insecticide Alphacypermetrine and herbicide Oxadiazon, used singly or in combination, on the most abundant frog in French rice fields, Pelophylax perezi.

    PubMed

    Mesléard, François; Gauthier-Clerc, Michel; Lambret, Philippe

    2016-07-01

    The potential impact of agricultural pesticides is a major concern with regard to biodiversity conservation. Pesticides are considered as one of the main causes of the worldwide decline of Amphibians. They are rarely used singly, but their cumulative impact and interaction are often neglected, as is the importance of the age or stage of the animal on which the impact of the molecules is assessed. We therefore tested the potential cumulative impact of the only authorized insecticide (Alphacypermetrine) and the main herbicide (Oxadiazon) used in French rice fields on four replicates of 25 eggs, young larvae and prometamorphosis tadpoles of the most abundant frog in paddies (Pelophylax perezi). We found no significant effect of the insecticide and herbicide, used singly or in combination, on hatching and young tadpoles. However, we found a strong impact of insecticide and herbicide used singly and a highly deleterious impact of their combined use on prometamorphosis tadpoles. Among the four replicates, only one of the prometamorphosis tadpoles did not reach this adult stage in the control against 9, 9, 6, 4 and 13, 9, 8, 7 with the herbicide and insecticide, respectively. But when the two pesticides were used in combination, only two prometamorphosis tapdoles reached the adult stage. Our results emphasize the potential impact on amphibians of pesticides used in agriculture and highlight the necessity of testing their role as cocktails. They also stress the importance of the age and/or stage of the target organism, the choice of which can lead to contrasting conclusions. Finally, our results suggest a possible underestimation of the impact of pesticides on non-targeted fauna in the rice fields in particular, and on living organisms in general.

  15. Finite deformation analysis of crack tip fields in plastically compressible hardening-softening-hardening solids

    NASA Astrophysics Data System (ADS)

    Khan, D.; Singh, S.; Needleman, A.

    2016-11-01

    Crack tip fields are calculated under plane strain small scale yielding conditions. The material is characterized by a finite strain elastic-viscoplastic constitutive relation with various hardening-softening-hardening hardness functions. Both plastically compressible and plastically incompressible solids are considered. Displacements corresponding to the isotropic linear elastic mode I crack field are prescribed on a remote boundary. The initial crack is taken to be a semi-circular notch and symmetry about the crack plane is imposed. Plastic compressibility is found to give an increased crack opening displacement for a given value of the applied loading. The plastic zone size and shape are found to depend on the plastic compressibility, but not much on whether material softening occurs near the crack tip. On the other hand, the near crack tip stress and deformation fields depend sensitively on whether or not material softening occurs. The combination of plastic compressibility and softening (or softening-hardening) has a particularly strong effect on the near crack tip stress and deformation fields.

  16. Finite deformation analysis of crack tip fields in plastically compressible hardening-softening-hardening solids

    NASA Astrophysics Data System (ADS)

    Khan, D.; Singh, S.; Needleman, A.

    2017-02-01

    Crack tip fields are calculated under plane strain small scale yielding conditions. The material is characterized by a finite strain elastic-viscoplastic constitutive relation with various hardening-softening-hardening hardness functions. Both plastically compressible and plastically incompressible solids are considered. Displacements corresponding to the isotropic linear elastic mode I crack field are prescribed on a remote boundary. The initial crack is taken to be a semi-circular notch and symmetry about the crack plane is imposed. Plastic compressibility is found to give an increased crack opening displacement for a given value of the applied loading. The plastic zone size and shape are found to depend on the plastic compressibility, but not much on whether material softening occurs near the crack tip. On the other hand, the near crack tip stress and deformation fields depend sensitively on whether or not material softening occurs. The combination of plastic compressibility and softening (or softening-hardening) has a particularly strong effect on the near crack tip stress and deformation fields.

  17. Magnetic field deformation due to electron drift in a Hall thruster

    NASA Astrophysics Data System (ADS)

    Liang, Han; Yongjie, Ding; Xu, Zhang; Liqiu, Wei; Daren, Yu

    2017-01-01

    The strength and shape of the magnetic field are the core factors in the design of the Hall thruster. However, Hall current can affect the distribution of static magnetic field. In this paper, the Particle-In-Cell (PIC) method is used to obtain the distribution of Hall current in the discharge channel. The Hall current is separated into a direct and an alternating part to calculate the induced magnetic field using Finite Element Method Magnetics (FEMM). The results show that the direct Hall current decreases the magnetic field strength in the acceleration region and also changes the shape of the magnetic field. The maximum reduction in radial magnetic field strength in the exit plane is 10.8 G for an anode flow rate of 15 mg/s and the maximum angle change of the magnetic field line is close to 3° in the acceleration region. The alternating Hall current induces an oscillating magnetic field in the whole discharge channel. The actual magnetic deformation is shown to contain these two parts.

  18. Viscoelastic deformation response of red blood cells under conditions of oscillating centrifugal field.

    PubMed

    Farges, E; Grebe, R; Baumann, M

    2003-01-01

    The red cell deformation under the conditions of oscillating centrifugal fields was studied. Experiments were carried out with a modified Cell-Elastometer operating in oscillating mode (0.02 to 0.30 Hz). Gravitational acceleration was sinusoidally modulated between 620 g and 2250 g. At low frequencies (below 0.08 Hz), native red cells followed the applied stress without delay. At 0.09 Hz and up, the cellular deformation was still periodical and included an additional perturbation due to intracellular movements. This perturbation was analysed and quantified. The influence of alterations on the erythrocyte membrane by diamide was analysed to verify the sensitivity of this method. On increasing the membrane stiffness with low concentrations of diamide, the response to oscillatory centrifugal stress was impaired characteristically in terms of amplitude deformation. Based on tangential and centrifugal accelerations, a physical model was developed that describes the basic observable changes on varying the oscillation frequency. From the data it can be concluded that viscoelastic properties of red cells can be analysed and quantified using oscillatory centrifugal accelerations. The described method can become a valid tool to differentiate between membrane alterations or intracellular viscous modifications.

  19. Supersymmetric moose models: An extra dimension from a broken deformed conformal field theory

    SciTech Connect

    Erlich, Joshua; Anly Tan, Jong

    2006-09-15

    We find a class of four dimensional deformed conformal field theories which appear extra dimensional when their gauge symmetries are spontaneously broken. The theories are supersymmetric moose models which flow to interacting conformal fixed points at low energies, deformed by superpotentials. Using a-maximization we give strong nonperturbative evidence that the hopping terms in the resulting latticized action are relevant deformations of the fixed-point theories. These theories have an intricate structure of RG flows between conformal fixed points. Our results suggest that at the stable fixed points each of the bulk gauge couplings and superpotential hopping terms is turned on, in favor of the extra-dimensional interpretation of the theory. However, we argue that the higher-dimensional gauge coupling is generically small compared to the size of the extra dimension. In the presence of a brane the topology of the extra dimension is determined dynamically and depends on the numbers of colors and bulk and brane flavors, which suggests phenomenological applications. The RG flows between fixed points in these theories provide a class of tests of Cardy's conjectured a-theorem.

  20. Sedimentary cover deformations in the equatorial Atlantic and their comparison with geophysical fields

    NASA Astrophysics Data System (ADS)

    Sokolov, S. Yu.

    2017-01-01

    The deformations of the sedimentary cover at near-latitudinal geotraverses west and east of the Mid-Atlantic Ridge in the equatorial part of ocean are compared with potential fields and variations of the V p/ V s attribute at a depth of 470 km. The features of sedimentary cover deformations in abyssal basins are formulated, as well as their differences from the undisturbed bedding of sediments. The elements of chain of phenomena with common spatial manifestations and cause-and-effect relationships have been established, including heterogeneous horizontal movements, which make up macrojointing above "cold" mantle blocks at a depth of 470 km; serpentinization of upper-mantle rocks; the formation of superposed magnetic anomalies; the release of the fluids, which acoustically bleach out the sedimentary sequence in seismic imaging; and decompaction of rocks leading to vertical motions and forced folding. The origin of the Atlantic marginal dislocation zone is explained. The coincidence of the deformation boundary in the equatorial Atlantic with the zero contour line of the V p/ V s attribute is revealed. This coincidence is an indicator of the rheological state of the upper mantle.

  1. Automatic construction of statistical shape models using deformable simplex meshes with vector field convolution energy.

    PubMed

    Wang, Jinke; Shi, Changfa

    2017-04-24

    In the active shape model framework, principal component analysis (PCA) based statistical shape models (SSMs) are widely employed to incorporate high-level a priori shape knowledge of the structure to be segmented to achieve robustness. A crucial component of building SSMs is to establish shape correspondence between all training shapes, which is a very challenging task, especially in three dimensions. We propose a novel mesh-to-volume registration based shape correspondence establishment method to improve the accuracy and reduce the computational cost. Specifically, we present a greedy algorithm based deformable simplex mesh that uses vector field convolution as the external energy. Furthermore, we develop an automatic shape initialization method by using a Gaussian mixture model based registration algorithm, to derive an initial shape that has high overlap with the object of interest, such that the deformable models can then evolve more locally. We apply the proposed deformable surface model to the application of femur statistical shape model construction to illustrate its accuracy and efficiency. Extensive experiments on ten femur CT scans show that the quality of the constructed femur shape models via the proposed method is much better than that of the classical spherical harmonics (SPHARM) method. Moreover, the proposed method achieves much higher computational efficiency than the SPHARM method. The experimental results suggest that our method can be employed for effective statistical shape model construction.

  2. FROGS (Friends of Granites) Report, Fall 1987

    NASA Astrophysics Data System (ADS)

    Miller, Calvin F.; Lawford, J.

    This is the first official FROGS report in Eos. Our purpose is to disseminate information about the status of felsic igneous petrology, providing information and opinions about research, ideas, and problems that relate especially to granitoids but also, clearly, to felsic volcanic rocks. A major goal has been to bridge the gap between field-based and experimental approaches. For several years, FROGS reports have existed as occasional informal newsletters, but we feel that our purposes will be better served by semiannual publication as a section of the VGP News. A briefer companion report will also be published in The Lattice, the newsletter of the Mineralogical Society of America.

  3. Current regional stress field and the resultant crustal deformation in SE Korea and their tectonic implication

    NASA Astrophysics Data System (ADS)

    Kim, M. C.; Cho, H.; Son, M.

    2014-12-01

    To determine current regional stress field and to characterize the resultant crustal deformation in SE Korea, Quaternary fault, focal mechanism, and geotechnical in-situ stress data were synthetically analyzed. The Quaternary faults are extensively observed along major inherited fault zones and show compatible orientations with general trends of the inherited faults. Most of the Quaternary faults have a top-to-the-west thrust geometry and kinematics and show a tendency of upward-decreasing dip angle and upward-narrowing gouge zone. Slip-sense indicators and paleo-stress field reconstructions indicate that the faults resulted from reverse or transpressional faulting under an E-W compression. All the magnetic fabrics (AMS) of the fault gouges also indicate the prevailing reverse-slip faulting under an ENE-WNW compression. The dominant oblate magnetic fabrics parallel to fault plane and the degrees of anisotropy increasing in proportion to their oblatenesses indicate that the fabrics have formed by a progressive deformation due to continuous simple shear during the last reactivation stage as reverse faulting. The focal mechanism study in and around the Korean Peninsula show the horizontally clustered P-axes in ENE-WSW direction and the girdle-distributed T-axes in NNW trend. The geotechnical in-situ stress data in south Korea also show NE- or ENE-trending maximum horizontal stress. The current crustal deformation in Korea thus can be characterized by contractional structures produced under a regional E-W or ENE-WSW compression stress field, and most of the Quaternary faults resulted from the local re-activation of appropriately oriented inherited major faults. Considering the tectonic setting and structural features in Asia during the Neogene, the current stress regime is interpreted to have been caused by the cooperation of westward shallow subduction of Pacific Plate and collision of Indian and Eurasian continents since about 5-3.5 Ma.

  4. Anharmonic magnetic deformation of spherical vesicle: Field-induced tension and swelling effects

    NASA Astrophysics Data System (ADS)

    Iwamoto, Mitsumasa; Ou-Yang, Zhong-can

    2013-12-01

    We have derived an equation, based on Helfrich’s curvature elasticity, describing the equilibrium shape of membrane vesicles in the presence of magnetic fields. We have solved this equation with and without the constraint of constant vesicle area. For vesicles with constant area, an exact calculation using our model confirms Helfrich’s estimate (Helfrich, 1973) [20] and predicts a magnetic field induced surface tension. Without the constant area constraint, our model predicts that vesicles with positive diamagnetic susceptibility anisotropy will swell in magnetic fields. It also predicts the anharmonic magnetic deformation of self-assembled nanocapsules of bola-amphiphilic molecules and the linear birefringence observed by Manyuhina et al. (2007) [22] .

  5. A simple solution for marginal deformations in open string field theory

    NASA Astrophysics Data System (ADS)

    Maccaferri, Carlo

    2014-05-01

    We derive a new open string field theory solution for boundary marginal deformations generated by chiral currents with singular self-OPE. The solution is algebraically identical to the Kiermaier-Okawa-Soler solution and it is gauge equivalent to the TakahashiTanimoto identity-based solution. It is wedge-based and we can analytically evaluate the Ellwood invariant and the action, reproducing the expected results from BCFT. By studying the isomorphism between the states of the initial and final background a dual derivation of the Ellwood invariant is also obtained.

  6. The INSAR technique: its principle and applications to mapping the deformation field of earthquakes

    NASA Astrophysics Data System (ADS)

    Shan, Xin-Jian; Ye, Hong

    1998-11-01

    The development, state-of-art and prospects of application of the radar remote sensing technique are presented. The principle of the INSAR (Interferometric Synthetic Aperture Radar) technique is expounded in more details. Some applications of this technique in measuring seismic dislocations are given. Finally, it is pointed out that INSAR has a non-replaceable application potential in observing ground surface vertical deformations; it would provide an entirely new means and method for monitoring the dynamic field of earthquakes and give an extremely great impetus to the future earthquake prediction work.

  7. Dense deformation field estimation for atlas-based segmentation of pathological MR brain images.

    PubMed

    Bach Cuadra, M; De Craene, M; Duay, V; Macq, B; Pollo, C; Thiran, J-Ph

    2006-12-01

    Atlas registration is a recognized paradigm for the automatic segmentation of normal MR brain images. Unfortunately, atlas-based segmentation has been of limited use in presence of large space-occupying lesions. In fact, brain deformations induced by such lesions are added to normal anatomical variability and they may dramatically shift and deform anatomically or functionally important brain structures. In this work, we chose to focus on the problem of inter-subject registration of MR images with large tumors, inducing a significant shift of surrounding anatomical structures. First, a brief survey of the existing methods that have been proposed to deal with this problem is presented. This introduces the discussion about the requirements and desirable properties that we consider necessary to be fulfilled by a registration method in this context: To have a dense and smooth deformation field and a model of lesion growth, to model different deformability for some structures, to introduce more prior knowledge, and to use voxel-based features with a similarity measure robust to intensity differences. In a second part of this work, we propose a new approach that overcomes some of the main limitations of the existing techniques while complying with most of the desired requirements above. Our algorithm combines the mathematical framework for computing a variational flow proposed by Hermosillo et al. [G. Hermosillo, C. Chefd'Hotel, O. Faugeras, A variational approach to multi-modal image matching, Tech. Rep., INRIA (February 2001).] with the radial lesion growth pattern presented by Bach et al. [M. Bach Cuadra, C. Pollo, A. Bardera, O. Cuisenaire, J.-G. Villemure, J.-Ph. Thiran, Atlas-based segmentation of pathological MR brain images using a model of lesion growth, IEEE Trans. Med. Imag. 23 (10) (2004) 1301-1314.]. Results on patients with a meningioma are visually assessed and compared to those obtained with the most similar method from the state-of-the-art.

  8. Manipulating nonclassical quantum statistical properties of light field by an f-deformed Bose-Einstein condensate

    NASA Astrophysics Data System (ADS)

    Darareh, M. Davoudi; Naderi, M. H.; Soltanolkotabi, M.

    2009-12-01

    We consider the interaction between an f-deformed Bose-Einstein condensate and a single-mode quantized light field. By using the Gardiner's phonon operators, we find that there exists a natural deformation in the model which modifies the Bogoliubov approximation under the condition of large but finite number of particles in condensate. This approach introduces an intrinsically deformed Bose-Einstein condensate, where the deformation parameter, well-defined by the particle number N in condensate, controls the strength of the associated nonlinearity. By introducing the deformed Gardiner's phonon operators we modify the very dilute-gas approximation through including atomic collisions in condensate. The rate of atomic collisions κ, as a new deformation parameter in the deformed Bose-Einstein condensate, controls the nonlinearity related to the atomic collisions. We show that by controlling the nonlinearities in the f-deformed atomic condensate through the two atomic parameters N and κ, it is possible to generate and manipulate the nonclassical quantum statistical properties of radiation field, such as, the sub-Poissonian photon statistics and quadrature squeezing. Also, it is possible to control the collapses and revivals phenomena in the average number of photons by atomic parameters N and κ.

  9. DEFORMED FROGS AND ENVIRONMENTAL RETINOIDS. (R827398)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  10. DEFORMED FROGS AND ENVIRONMENTAL RETINOIDS. (R827398)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  11. Field and Lava Flow Experiment Analysis of Vesicle Deformation as a Means of Determining Ancient Flow Direction

    NASA Astrophysics Data System (ADS)

    McColl, B.; Teasdale, R.

    2006-12-01

    The goal of this work is to test whether flow direction of ancient lavas can be determined from orientations of preserved vesicles. We have attempted to correlate field observations with lab experiments as a means of understanding the development of deformed vesicles. This work focuses on vesicles deformed parallel to the lava flow direction. On a fieldtrip, we observed deformed vesicles in basaltic lava flows at cinder cones in the Coso Volcanic Field. Other basalt flows with similarly deformed vesicles are also documented in the Lovejoy Basalt (Chico, CA) and in flows at Lava Beds National Monument, Medicine Lake Volcanic Field. We believe that the vesicles were deformed during lava flow emplacement and cooling. Analog flow experiments used materials with Newtonian behavior (honey, syrup) but Bingham fluid behavior is more similar to natural lavas so gelatin was also attempted. Experiments started with the analog fluids on a horizontal surface. Air was then injected into the fluids with a hypodermic needle and then the surface was inclined to approximately 4-5 degrees. The deformation of the bubbles in the analog fluids was recorded with digital photos taken from above the flows. In some cases, bubbles rose to the surface of the flow and were not deformed parallel to the flow direction. In other cases, bubbles were deformed and we recorded a bulbous end and elongate tail parallel to the flow direction. In all cases the bulbous end of deformed vesicles are directed down stream and a tail stretches behind. Honey best preserved vesicle deformation. Bubbles in syrup rose to the surface too quickly to document (even when syrup was chilled). Air injected into gelatin caused shear, releasing the air without forming bubbles. Future work will address analog material issues by using wax or polyethylene glycol (PEG). These materials are likely to better represent rheologies of basalt lavas during flow emplacement.

  12. Frog Swarms: Earthquake Precursors or False Alarms?

    PubMed Central

    Grant, Rachel A.; Conlan, Hilary

    2013-01-01

    juvenile animals migrating away from their breeding pond, after a fruitful reproductive season. As amphibian populations undergo large fluctuations in numbers from year to year, this phenomenon will not occur on a yearly basis but will depend on successful reproduction, which is related to numerous climatic and geophysical factors. Hence, most large swarms of amphibians, particularly those involving very small frogs and occurring in late spring or summer, are not unusual and should not be considered earthquake precursors. In addition, it is likely that reports of several mass migration of small toads prior to the Great Sichuan Earthquake in 2008 were not linked to the subsequent M = 7.9 event (some occurred at a great distance from the epicentre), and were probably co-incidence. Statistical analysis of the data indicated frog swarms are unlikely to be connected with earthquakes. Reports of unusual behaviour giving rise to earthquake fears should be interpreted with caution, and consultation with experts in the field of earthquake biology is advised. PMID:26479746

  13. Nanoscale mapping of the three-dimensional deformation field within commercial nanodiamonds

    DOE PAGES

    Maqbool, Muhammad Salman; Hoxley, David; Phillips, Nicholas W.; ...

    2017-02-21

    Here, the unique properties of nanodiamonds make them suitable for use in a wide range of applications, including as biomarkers for cellular tracking in vivo at the molecular level. The sustained fluorescence of nanodiamonds containing nitrogen-vacancy (N-V) centres is related to their internal structure and strain state. Theoretical studies predict that the location of the N-V centre and the nanodiamonds' residual elastic strain state have a major influence on their photoluminescence properties. However, to date there have been no direct measurements made of their spatially resolved deformation fields owing to the challenges that such measurements present. Here we apply themore » recently developed technique of Bragg coherent diffractive imaging (BCDI) to map the three-dimensional deformation field within a single nanodiamond of approximately 0.5 µm diameter. The results indicate that there are high levels of residual elastic strain present in the nanodiamond which could have a critical influence on its optical and electronic properties.« less

  14. Effect of uniform electric field on the drop deformation in simple shear flow and emulsion shear rheology

    NASA Astrophysics Data System (ADS)

    Mandal, Shubhadeep; Chakraborty, Suman

    2017-07-01

    Electrohydrodynamic deformation and orientation of a neutrally buoyant, leaky dielectric, Newtonian drop suspended in another immiscible, leaky dielectric, Newtonian medium is analyzed under the combined influence of uniform electric field and simple shear flow. Application of uniform electric field, perpendicular to the direction of shear flow, not only deforms the drop but also modifies the rheological behavior of a dilute emulsion. In the creeping flow limit, an analytical solution for the deformed drop shape is obtained when the drop shape remains nearly spherical and the surface charge convection is weak. The effective shear rheology is obtained for a dilute emulsion of non-interacting drops by calculating the one-particle contribution to the emulsion stress. The results show that the combined influence of uniform electric field and shear flow is not a simple linear superposition of the independent contributions from electric field and shear flow. Application of uniform electric field always leads to larger drop deformation with drop inclination more towards the direction of velocity gradient for the particular case of perfectly dielectric drops. Presence of surface charge convection for a leaky dielectric drop can increase or decrease the drop deformation with the drop inclination more towards either the direction of shear flow or velocity gradient. The effective shear viscosity and normal stress differences are found to be independent of shear rate. These quantities are significantly affected by the surface charge convection and shape deformation. Shape deformation always increases the effective viscosity of a dilute emulsion composed of perfectly dielectric drops. Interestingly, for a dilute emulsion composed of leaky dielectric drops, results show that the combined influence of charge convection and shape deformation can augment or decrease the effective shear viscosity.

  15. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    DOE PAGES

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; ...

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It ismore » found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.« less

  16. Deformation-induced spatiotemporal fluctuation, evolution and localization of strain fields in a bulk metallic glass

    SciTech Connect

    Wu, Yuan; Bei, Hongbin; Wang, Yanli; Lu, Zhaoping; George, Easo P.; Gao, Yanfei

    2015-05-16

    Deformation behavior and local strain evolutions upon loading and unloading of a bulk metallic glass (BMG) were systematically investigated by in situ digital image correlation (DIC). Distinct fluctuations and irreversible local strains were observed before the onset of macroscopic yielding. Statistical analysis shows that these fluctuations might be related to intrinsic structural heterogeneities, and that the evolution history and characteristics of local strain fields play an important role in the subsequent initiation of shear bands. Effects of sample size, pre-strain, and loading conditions were systematically analyzed in terms of the probability distributions of the resulting local strain fields. It is found that a higher degree of local shear strain heterogeneity corresponds to a more ductile stressestrain curve. Implications of these findings are discussed for the design of new materials.

  17. Effect of the particular temperature field on a National Ignition Facility deformable mirror

    NASA Astrophysics Data System (ADS)

    Bian, Qi; Huang, Lei; Ma, Xingkun; Xue, Qiao; Gong, Mali

    2016-09-01

    The changes caused by temperature in the surface shape of a deformable mirror used at the National Ignition Facility has been investigated previously. In this paper the temperature induced surface shape under different temperature fields is further studied. We find that the changes of the peak and valley (PV) or root-mean-square (RMS) value rely on the temperature gradient as well as the difference between the mirror and the environment with a certain rule. This work analyzes these quantitative relationship, using the finite element method. Some experiments were carried out to verify the analysis results. The conclusion provides guidance to minimize the effect of the temperature field on the surface shape. Considerations about how to improve the temperature induced faceplate in actual work are suggested finally.

  18. Peatlands and green frogs: A relationship regulated by acidity?

    USGS Publications Warehouse

    Mazerolle, M.J.

    2005-01-01

    The effects of site acidification on amphibian populations have been thoroughly addressed in the last decades. However, amphibians in naturally acidic environments, such as peatlands facing pressure from the peat mining industry, have received little attention. Through two field studies and an experiment, I assessed the use of bog habitats by the green frog (Rana clamitans melanota), a species sensitive to various forestry and peat mining disturbances. First, I compared the occurrence and breeding patterns of frogs in bog and upland ponds. I then evaluated frog movements between forest and bog habitats to determine whether they corresponded to breeding or postbreeding movements. Finally, I investigated, through a field experiment, the value of bogs as rehydrating areas for amphibians by offering living Sphagnum moss and two media associated with uplands (i.e., water with pH ca 6.5 and water-saturated soil) to acutely dehydrated frogs. Green frog reproduction at bog ponds was a rare event, and no net movements occurred between forest and bog habitats. However, acutely dehydrated frogs did not avoid Sphagnum. Results show that although green frogs rarely breed in bogs and do not move en masse between forest and bog habitats, they do not avoid bog substrates for rehydrating, despite their acidity. Thus, bogs offer viable summering habitat to amphibians, which highlights the value of these threatened environments in terrestrial amphibian ecology.

  19. Jan Swammerdam's frogs

    PubMed Central

    Sleigh, Charlotte

    2012-01-01

    Having discussed insect metamorphosis at length, Jan Swammerdam's Bybel der Natuure (1679/1737) reached its climax with a substantial description of the generation and muscular activity of frogs. This paper explores the rhetorical role of frogs in Swammerdam's ‘great work’, showing how they were the Archimedean point from which he aimed to reorder all of creation—from insects to humans—within one glorious, God-ordained natural history and philosophy. Swammerdam linked insects to frogs through a demonstration that all underwent epigenesis; and frogs were then linked to humans through a demonstration of their identical muscular activity. The success of Swammerdam's strategy required a theological reconstruction of the frog, traditionally an ungodly creature, such that trustworthy knowledge could be obtained from its body. Perhaps surprisingly, this act of theological cleansing is shown to be somewhat prefigured in the distinctly non-experimental natural history of Edward Topsell (1608). The paper also examines Swammerdam's interactions with the mystic Antoinette Bourignon, and his challenges in reconciling a spirituality of meletetics with a material epistemology in natural philosophy. Differences are revealed between the natural analogies given by Swammerdam in his published and unpublished writings, undermining to a certain extent the triumphal insect–frog–human rhetorical structure of the Bybel.

  20. Impact of radial external magnetic field on plasma deformation during contact opening in SF6 circuit breakers

    NASA Astrophysics Data System (ADS)

    Abbasi, V.; Gholami, A.; Niayesh, K.

    2012-10-01

    A three-dimensional (3D) transient model is developed to investigate plasma current deformation driven by internal and external magnetic fields and their influences on arc stability in a circuit breaker. The 3D distribution of electric current density is obtained by solving the current continuity equation along with the generalized Ohm's law in the presence of an external magnetic field, while the magnetic field induced by the current flowing through the arc column is calculated by the magnetic vector potential equation. The applied external field imposes a rotational electromagnetic force on the arc and influences the plasma current deformation, which is discussed in this paper. In SF6 circuit breakers when gas interacts with the arc column, the fundamental equations such as Ampere's law, Ohm's law, turbulence model, transport equations of mass, momentum, and energy of plasma flow have to be coupled for analysing the phenomenon. The coupled interactions between the arc and the plasma flow are described within the framework of magnetohydrodynamic equations in conjunction with a K-ɛ turbulence model. Simulations are focused on sausage and kink instabilities in the plasma (these phenomena are related to the electromagnetic field distribution and define the plasma deformations). The 3D simulation reveals the relation between plasma current deformation and instability phenomena, which affects the arc stability during the operation. Plasma current deformation is a consequence of coupling between electromagnetic forces (resulting from internal and radial external magnetic fields) and the plasma flow that are described in the simulations.

  1. Central and eastern Anatolian crustal deformation rate and velocity fields derived from GPS and earthquake data

    NASA Astrophysics Data System (ADS)

    Simão, N. M.; Nalbant, S. S.; Sunbul, F.; Komec Mutlu, A.

    2016-01-01

    We present a new strain-rate and associated kinematic model for the eastern and central parts of Turkey. In the east, a quasi N-S compressional tectonic regime dominates the deformation field and is partitioned through the two major structural elements of the region, which are the conjugate dextral strike-slip North Anatolian Fault Zone (NAFZ) and the sinistral strike slip East Anatolian Fault Zone (EAFZ). The observed surface deformation is similar to that inferred by anisotropy studies which sampled the region of the mantle closer to the crust (i.e. the lithospheric mantle and the Moho), and is dependent on the presence or absence of a lithospheric mantle, and of the level of coupling between it and the overlaying crust. The areas of the central and eastern parts of Turkey which are deforming at elevated rates are situated above areas with strong gradients in crustal thickness. This seems to indicate that these transition zones, situated between thinner and thicker crusts, promote more deformation at the surface. The regions that reveal elevated strain-rate values are 1) the Elaziğ-Bingol segment of the EAFZ, 2) the region around the Karlıova triple-junction including the Yedisu segment and the Varto fault, 3) the section of the NAFZ that extends from the Erzincan province up to the NAFZ-Ezinepazarı fault junction, and 4) sections of the Tuz Gölü Fault Zone. Other regions like the Adana basin, a significant part of the Central Anatolian Fault Zone (CAFZ), the Aksaray and the Ankara provinces, are deforming at smaller but still considerable rates and therefore should be considered as areas well capable of producing damaging earthquakes (between M6 and 7). This study also reveals that the central part of Turkey is moving at a faster rate towards the west than the eastern part Turkey, and that the wedge region between the NAFZ and the EAFZ accounts for the majority of the counter clockwise rotation between the eastern and the central parts of Turkey. This

  2. Combined effect of the electric current magnetic field and microwave radiation during the deformation of the stainless steel

    NASA Astrophysics Data System (ADS)

    Troitskiy, O. A.; Stashenko, V. I.

    2017-07-01

    The work determines the influence of microwave radiation on the processes of active deformation and relaxation of mechanical stresses in loaded samples of stainless steel under the effect of current pulses and longitudinal and transverse orientation of the electric-field vector E of the microwave radiation to the axis of the deformated sample. With the longitudinal orientation of the vector E of the microwave radiation and under the action of the current the effect of metal softening increased from 22% to 30%. The analysis of the microstructure of the samples showed a significant influence of external energy impacts on the deformation of steel grains.

  3. Natural levels of abnormalities in the trilling frog (neobactrachus centralis) at the Olympic dam mine

    SciTech Connect

    Read, J.L. ); Tyler, M.J. )

    1994-07-01

    Frogs are more susceptible than most vertebrates to environmental contaminants. Unlike amniotes, the frog egg is not protected by a semi-impervious shell, and hence is readily exposed to pollutants. In addition, tadpoles develop in wetlands to which many noxious substances drain from the surrounding landscape. Coupled with this high exposure rate, frogs are also very sensitive to trace elements, some pesticides, heavy metals especially when coupled with exposure to low pH and ionizing radiation. Frogs commonly exhibit discernible deformities following exposure to teratogenic contaminants, and therefore are valuable indicators of the existence of noxious substances in the environment. The abundance and ease of sampling of frogs, along with their sensitivity to environmental contaminants, makes them ideal organisms for environmental monitoring in the Australian arid zone. The study of abnormalities in frogs has become an integral part of the Environmental Management Programme of the Olympic Dam Operations (ODO) copper-uranium-gold-silver mine in northern South Australia. The Trilling Frog (Neobatrachus centralis) is the only frog species which has been recorded at Olympic Dam. It is likely that these frogs, are relatively sedentary, thus enhancing their value as indicator organisms. A pilot survey in 1989 documented frog deformity levels comparable to those found at undisturbed sites in Australia and in other countries. This paper reports on larger study conducted in February and March 1992 when heavy rains provided another opportunity to survey the frog population. The low levels of abnormalities support the conclusion that N. centralis at Olympic Dam does not appear to be accumulating or being influenced by the very low levels of radionuclides present here.

  4. Deformation of the free surface of a conducting fluid in the magnetic field of current-carrying linear conductors

    NASA Astrophysics Data System (ADS)

    Zubarev, N. M.; Zubareva, O. V.

    2017-06-01

    The magnetic shaping problem is studied for the situation where a cylindrical column of a perfectly conducting fluid is deformed by the magnetic field of a system of linear current-carrying conductors. Equilibrium is achieved due to the balance of capillary and magnetic pressures. Two two-parametric families of exact solutions of the problem are obtained with the help of conformal mapping technique. In accordance with them, the column essentially deforms in the cross section up to its disintegration.

  5. Geodetic measurements and numerical models of deformation at the Svartsengi Geothermal Field, Iceland, 1992 - 2010

    NASA Astrophysics Data System (ADS)

    Feigl, K.; Ali, T.; Wang, H. F.; Fridleifsson, G. O.; Sigurdsson, O.; Sigmundsson, F.

    2012-12-01

    To study rheology — the constitutive relations between stress and strain— we apply a known impulse to a mechanical system and then measure the subsequent response. For example, by ringing a bell and listening to the resulting sound, we can infer that the material in the bell behaves as an elastic solid with little attenuation. By modeling the impulse (stress) and measuring the response (strain), and defining the constitutive relations between the two, we can make inferences about the underlying physical processes. In the case of the earth, the response is crustal deformation that can be measured using interferometric synthetic aperture radar (InSAR). Such experiments are feasible where industrial extraction of oil, gas, water, or heat causes subsidence, provided that data are available to describe both the impulse and the response. The Svartsengi geothermal field meets the requirements for a rheological experiment. Located on the Reykjanes Peninsula in Iceland, it is associated with a segment of mid-ocean ridge of the same name. The operators of the Svartsengi field have monitored the water level, borehole pressure and surface deformation since beginning production in 1976. In this study, we analyze radar images acquired on 78 distinct dates between 1992 and 2010 by six satellite missions: ERS-1, ERS-2, Envisat, ALOS, TerraSAR-X, and TanDEM-X. As in previous studies (Vadon and Sigmundsson, 1997, Keiding et al., 2010), the InSAR results indicate subsidence at the order of several centimeters per year over an area roughly five kilometers in radius. To describe this deformation, one can consider a simple model that assumes a half space with uniform elastic properties. For a reservoir shaped like a prolate spheroid, the model parameters include depth, length of the semi-major axis, width of the semi-minor axis, strike of the spheroid axis, plunge of the spheroid axis, and a pressure change (Yang et al., 1988). This model has been applied to the Coso geothermal

  6. Hyperbolic deformation of a gauge field theory and the hierarchy problem

    NASA Astrophysics Data System (ADS)

    Cartas-Fuentevilla, R.; Escalante-Hernandez, A.; Herrera-Aguilar, A.

    2016-11-01

    The problem of the gauge hierarchy is brought up in a hypercomplex scheme for a U(1) field theory; in such a scheme, a compact gauge group is deformed through a γ-parameter that varies along a noncompact internal direction, transverse to the U(1) compact one, and thus an additional SO(1, 1) gauge symmetry is incorporated. This transverse direction can be understood as an extra internal dimension, which will control the spontaneous symmetry breakdown, and will allow us to establish a mass hierarchy. In this mechanism, there is no brane separation to be estabilized as in the braneworld paradigm, however, a different kind of fine-tuning is needed in order to generate the wished electroweak/Planck hierarchy. By analyzing the effective self-interactions and mass terms of the theory, an interesting duality is revealed between the real and hybrid parts of the effective potential. This duality relates the weak and strong self-interaction regimes of the theory, due to the fact that both mass terms and self-coupling constants appear as one-parameter flows in γ. Additionally, the γ-deformation will establish a flow for the electromagnetic coupling that mimics the renormalization group flow for the charge in QED.

  7. Nonrigid 2D registration of fluoroscopic coronary artery image sequence with propagated deformation field

    NASA Astrophysics Data System (ADS)

    Park, Taewoo; Shin, Seung Yeon; Hong, Youngtaek; Lee, Soochahn; Chang, Hyuk-Jae; Yun, Il Dong

    2017-03-01

    We propose a novel method for nonrigid registration of coronary arteries within frames of a fluoroscopic X-ray angiogram sequence with propagated deformation field. The aim is to remove the motion of coronary arteries in order to simplify further registration of the 3D vessel structure obtained from computed tomography angiography, with the x-ray sequence. The Proposed methodology comprises two stages: propagated adjacent pairwise nonrigid registration, and, sequence-wise fixed frame nonrigid registration. In the first stage, a propagated nonrigid transformation reduces the disparity search range for each frame sequentially. In the second stage, nonrigid registration is applied for all frames with a fixed target frame, thus generating a motion-aligned sequence. Experimental evaluation conducted on a set of 7 fluoroscopic angiograms resulted in reduced target registration error, compared to previous methods, showing the effectiveness of the proposed methodology.

  8. Contrasts between deformation accommodated by induced seismic and aseismic processes revealed by combined monitoring of seismicity and surface deformations: Brady Geothermal Field, Nevada, USA

    NASA Astrophysics Data System (ADS)

    Davatzes, N. C.; Ali, S. T.; Mellors, R. J.; Foxall, W.; Wang, H. F.; Feigl, K. L.; Drakos, P. S.; Zemach, E.

    2013-12-01

    Fluid pressure change accompanying pumping in the Brady Geothermal Field is associated with two easily measureable deformation responses: (1) surface deformations and 2) seismic slip. Surface deformation can be imaged by InSAR and appears to correspond to volume change at depth. Seismic slip on fractures is likely induced by either changes in effective normal stress or solid stress with minimal impact to volume. Both responses have potential impact on permeability structure due to dilation or compaction along natural fractures. We present an integrated data set that compares pumping records with these deformation responses to investigate their coupling and to constrain the geometry and rheology of the reservoir and surrounding crust. We also seek to clarify the relationship between induced seismicity and pumping. Currently, the dominant pumping signal is pressure reduction resulting from on-going production since 1992. Surface subsidence extends over a region of approximately 5 km by 2 km with the long axis along the strike of the major normal faults associated with the reservoir. Smaller approximately 1 km length-scale regions of intense subsidence are associated bends or intersections among individual normal fault segments. Modeling of the deformation source indicates that the broader subsidence pattern is consistent with the majority of fluid extraction from a reservoir at a depth of approximately 1 km and extending along the entire length of the mapped Brady normal fault. The more intense subsidence is consistent with fluid extraction along steep conduits from shallower depths that extend to the main reservoir. These results indicate a reservoir much larger than would be expected from the footprint of the production wells. In contrast, seismicity is primarily concentrated along a narrow path between injecting and producing wells, but outside the regions of most intense subsidence. Overall, seismicity represents only a small fraction of the strain energy

  9. Coulomb form factors of odd-A nuclei within an axially deformed relativistic mean-field model

    NASA Astrophysics Data System (ADS)

    Liu, Jian; Xu, Chang; Wang, Shuo; Ren, Zhongzhou

    2017-09-01

    Background: The nuclear Coulomb form factor | FC(q) | 2 is a useful tool to study nuclear structure. For spherical nuclei, | FC(q) | 2 can be calculated by combining the spherical relativistic mean-field (RMF) model and the distorted wave Born approximation (DWBA) method. Purpose: In a previous paper, the axially deformed RMF model + DWBA method was successfully applied to study the Coulomb form factors of deformed even-even nuclei. In this paper, we further extend this method to study the Coulomb form factors of deformed odd-A nuclei. Method: First, the charge distributions of odd-A nuclei are calculated with the deformed RMF model and expanded into multipole components. Next, with the multipole moment charge distributions, the Coulomb multipoles C 0 , C 2 , and C 4 are calculated. Finally, by summing over Coulomb multipoles required, the Coulomb form factors of odd-A nuclei can be obtained. Results: For deformed odd-A nuclei, the theoretical Coulomb form factors calculated from the deformed RMF charge densities are in better agreement with the experimental data. For nuclei with J ≥1 , the diffraction minima of Coulomb form factors are much flatter, which is due to the contributions of quadrupole charge distributions. Conclusions: Results indicate that the axially deformed RMF model can give reasonable descriptions for multipole moment charge distributions of odd-A nuclei. The method in this paper can provide a useful guide for future experiments of electron scattering off exotic odd-A nuclei.

  10. From frog integument to human skin: dermatological perspectives from frog skin biology.

    PubMed

    Haslam, Iain S; Roubos, Eric W; Mangoni, Maria Luisa; Yoshizato, Katsutoshi; Vaudry, Hubert; Kloepper, Jennifer E; Pattwell, David M; Maderson, Paul F A; Paus, Ralf

    2014-08-01

    For over a century, frogs have been studied across various scientific fields, including physiology, embryology, neuroscience, (neuro)endocrinology, ecology, genetics, behavioural science, evolution, drug development, and conservation biology. In some cases, frog skin has proven very successful as a research model, for example aiding in the study of ion transport through tight epithelia, where it has served as a model for the vertebrate distal renal tubule and mammalian epithelia. However, it has rarely been considered in comparative studies involving human skin. Yet, despite certain notable adaptations that have enabled frogs to survive in both aquatic and terrestrial environments, frog skin has many features in common with human skin. Here we present a comprehensive overview of frog (and toad) skin ontogeny, anatomy, cytology, neuroendocrinology and immunology, with special attention to its unique adaptations as well as to its similarities with the mammalian integument, including human skin. We hope to provide a valuable reference point and a source of inspiration for both amphibian investigators and mammalian researchers studying the structural and functional properties of the largest organ of the vertebrate body.

  11. Deformation in lead zirconate titanate ceramics under large signal electric field loading measured by digital image correlation

    NASA Astrophysics Data System (ADS)

    Chen, Di; Kamlah, Marc

    2015-11-01

    Digital image correlation, a noncontact and nondestructive method, was employed to monitor the deformation of lead zirconate titanate piezoelectric ceramics. This method is based on imaging a speckle pattern on the specimen surface during the test and subsequently correlating each image of the deformed pattern to that in the reference state. In our work, both longitudinal and transverse strains were calculated from imaging a bulk sample under a ±2 kV/mm electric field. Compared with linear variable displacement transducer data, the results from this correlation method were validated. At the same time, based on this optical technique, different strain-electric field butterfly loops can be drawn from correspondingly selected regions of interest. Combined with contour plots of strain on the surface of the sample, the deformation of bulk ceramic sample under uniaxial electric field loading without any mechanical constraints is proven to be highly homogenous under macro-observing scale.

  12. Deformation in lead zirconate titanate ceramics under large signal electric field loading measured by digital image correlation.

    PubMed

    Chen, Di; Kamlah, Marc

    2015-11-01

    Digital image correlation, a noncontact and nondestructive method, was employed to monitor the deformation of lead zirconate titanate piezoelectric ceramics. This method is based on imaging a speckle pattern on the specimen surface during the test and subsequently correlating each image of the deformed pattern to that in the reference state. In our work, both longitudinal and transverse strains were calculated from imaging a bulk sample under a ±2 kV/mm electric field. Compared with linear variable displacement transducer data, the results from this correlation method were validated. At the same time, based on this optical technique, different strain-electric field butterfly loops can be drawn from correspondingly selected regions of interest. Combined with contour plots of strain on the surface of the sample, the deformation of bulk ceramic sample under uniaxial electric field loading without any mechanical constraints is proven to be highly homogenous under macro-observing scale.

  13. Information quantifiers, entropy squeezing and entanglement properties of superconducting qubit-deformed bosonic field system under dephasing effect

    NASA Astrophysics Data System (ADS)

    Berrada, K.; Al-Rajhi, M. A.

    2017-10-01

    In this paper, we present a detailed study on the evolution of some measures of nonclassicality and entanglement in the framework of the interaction between a superconducting qubit and deformed bosonic fields under decoherence effect. We compare the dynamical behavior of the different quantum quantifiers by exploiting a large set of nonlinear bosonic fields that are characterized by the deformation parameter. Additionally, we demonstrate how the connection between the appearance of the nonlinearity in the deformed field and the quantum information quantifiers. The time correlation between entropy squeezing, purity, and entanglement is examined in terms of the physical parameters involved in the whole system. Lastly, we explore the exact ranges of the physical parameters in order to combat the decoherence effect and maintain high amount of entanglement during the time evolution.

  14. Three-dimensional mapping of a deformation field inside a nanocrystal

    NASA Astrophysics Data System (ADS)

    Pfeifer, Mark A.; Williams, Garth J.; Vartanyants, Ivan A.; Harder, Ross; Robinson, Ian K.

    2006-07-01

    Coherent X-ray diffraction imaging is a rapidly advancing form of microscopy: diffraction patterns, measured using the latest third-generation synchrotron radiation sources, can be inverted to obtain full three-dimensional images of the interior density within nanocrystals. Diffraction from an ideal crystal lattice results in an identical copy of this continuous diffraction pattern at every Bragg peak. This symmetry is broken by the presence of strain fields, which arise from the epitaxial contact forces that are inevitable whenever nanocrystals are prepared on a substrate. When strain is present, the diffraction copies at different Bragg peaks are no longer identical and contain additional information, appearing as broken local inversion symmetry about each Bragg point. Here we show that one such pattern can nevertheless be inverted to obtain a `complex' crystal density, whose phase encodes a projection of the lattice deformation. A lead nanocrystal was crystallized in ultrahigh vacuum from a droplet on a silica substrate and equilibrated close to its melting point. A three-dimensional image of the density, obtained by inversion of the coherent X-ray diffraction, shows the expected facetted morphology, but in addition reveals a real-space phase that is consistent with the three-dimensional evolution of a deformation field arising from interfacial contact forces. Quantitative three-dimensional imaging of lattice strain on the nanometre scale will have profound consequences for our fundamental understanding of grain interactions and defects in crystalline materials. Our method of measuring and inverting diffraction patterns from nanocrystals represents a vital step towards the ultimate goal of atomic resolution single-molecule imaging that is a prominent justification for development of X-ray free-electron lasers.

  15. Mechanical heterogeneities along carbonate-bearing faults constrained from field and rock deformation experiments

    NASA Astrophysics Data System (ADS)

    Collettini, Cristiano; Carpenter, Brett; Tesei, Telemaco; Viti, Cecilia; Di Stefano, Giuseppe; Mollo, Silvio; Scarlato, Piergiorgio; Chiaraluce, Lauro

    2014-05-01

    Recent high-resolution GPS and seismological data have revealed that tectonic faults exhibit complex, multi-mode slip behavior. One way to improve our understanding of processes controlling the mode of slip is to study fault rock microstructures, collected from ancient faults exposed at Earth's surface or in deep boreholes and to characterize friction of the collected fault rocks. In several seismically active regions, like Italy, Greece, Iran, and China, a significant number of earthquakes nucleate and/or propagate through carbonates. For these reasons, we have been working to improve the characterization of carbonate bearing faults by integrating field and microstructural studies with mechanical data. Along some portions of carbonate fault zones: 1) the localization of deformation along sharp principal slipping zones (0.1-1 mm) made of fine-grained (0.1-10 μm) ultracataclasite and 2) the velocity weakening behavior of this material suggest a fast and seismic mechanism. Microstructural evidence indicates that seismic mechanisms are associated with thermally activated processes (i.e. dehydration and decarbonation). In other portions of these fault zones: 1) the distribution of deformation over thick (< 200 m) shear zones affected by pressure solution of carbonates and frictional sliding along foliated and clay-rich (illite-smectite) horizons, and 2) the velocity strengthening behavior of these foliated rocks indicate a slow and aseismic slip behavior. Sharp principal slipping zones that show high friction and significant re-strengthening during hold periods, indicate a fault patch capable of unstable slip with the ability to regain elastic strain energy. Conversely, phyllosilicate-rich shear zones showing low friction with no frictional healing suggest fault patches that can slip slowly and continuously with time. We are currently using a new biaxial apparatus with a pressure vessel to work on a large, 20x20 cm, experimental fault. In this fault we are reproducing

  16. Biosensor, ELISA, and frog embryo teratogenesis assay: Xenopus (FETAX) analysis of water associated with frog malformations in Minnesota

    NASA Astrophysics Data System (ADS)

    Garber, Eric A. E.; Erb, Judith L.; Downward, James G.; Priuska, Eric M.; Wittliff, James L.; Feng, Wenke; Magner, Joseph; Larsen, Gerald L.

    2001-03-01

    Between 1995 and 1997 over 62% of the counties in Minnesota reported the presence of malformed frogs. While most sites have recently shown a decline in malformed frog populations, one site in northeastern Minnesota with no prior history of containing malformed frogs was recently discovered to contain > 67% malformed Rana pipiens (northern leopard frogs). As part of an effort to study the presence of hormonally active agents in fresh water sources, water samples were collected from lakes in Minnesota containing malformed frogs and analyzed for the presence of hormonally active compounds using a novel evanescent field fluorometric biosensor and the frog embryo teratogenesis assay: Xenopus (FETAX) bioassay. The waveguide based biosensor developed by ThreeFold Sensors (TFS biosensor, Ann Arbor, MI) detects the presence of estrogenic compounds capable of interacting with free human ER-a and by inhibiting binding to an immobilized estrogen. The FETAX bioassay is a developmental assay, which measures teratogenicity, mortality, and inhibition of growth during the first 96 hours of organogenesis and thereby provides a universal screen for endocrine disruptors. TFS biosensor and FETAX screening of the water samples suggest a relationship between estrogenic activity, mineral supplementation, and the occurrence of malformed frogs.

  17. Wide Field Of View Varifocal Near-Eye Display Using See-Through Deformable Membrane Mirrors.

    PubMed

    Dunn, David; Tippets, Cary; Torell, Kent; Kellnhofer, Petr; Aksit, Kaan; Didyk, Piotr; Myszkowski, Karol; Luebke, David; Fuchs, Henry

    2017-04-01

    Accommodative depth cues, a wide field of view, and ever-higher resolutions all present major hardware design challenges for near-eye displays. Optimizing a design to overcome one of these challenges typically leads to a trade-off in the others. We tackle this problem by introducing an all-in-one solution - a new wide field of view, gaze-tracked near-eye display for augmented reality applications. The key component of our solution is the use of a single see-through, varifocal deformable membrane mirror for each eye reflecting a display. They are controlled by airtight cavities and change the effective focal power to present a virtual image at a target depth plane which is determined by the gaze tracker. The benefits of using the membranes include wide field of view (100° diagonal) and fast depth switching (from 20 cm to infinity within 300 ms). Our subjective experiment verifies the prototype and demonstrates its potential benefits for near-eye see-through displays.

  18. Numerical simulation of drop deformations and breakup modes caused by direct current electric fields

    NASA Astrophysics Data System (ADS)

    Paknemat, H.; Pishevar, A. R.; Pournaderi, P.

    2012-10-01

    A drop suspended in another fluid shows different dynamic behaviors in an electric field that depends on its physical properties. The phenomenon of drop deformation under the application of an electric field, in the absence of a net volume charge, is simply caused by the surface stresses. Therefore, an accurate method is required for numerical modeling of the electric driving force at the interface to handle all of the discontinuities involved in the model. For this purpose, in this study the level set method is used along with the ghost fluid method to investigate the responses of three types of drop in the presence of an electric field. Moreover, to demonstrate the accuracy of the method, the breakup modes of each electric model are carefully simulated. Finally, the results of the simulations are compared with similar numerical and experimental results from the literature. The simulation results indicate the accuracy of the method for modeling of the phenomenon over a wide range of electric capillary numbers, and particularly for the capture of the drop profile at the instant of disintegration.

  19. It's a Frog's Life

    ERIC Educational Resources Information Center

    Coffey, Audrey L.; Sterling, Donna R.

    2003-01-01

    When a preschool teacher unexpectedly found tadpoles in the school's outdoor baby pool, she recognized an unusual opportunity for her students to study pond life up close. By following the tadpoles' development, students learned about frogs, life cycles, habitats. (Contains 1 resource.)

  20. It's a Frog's Life

    ERIC Educational Resources Information Center

    Coffey, Audrey L.; Sterling, Donna R.

    2003-01-01

    When a preschool teacher unexpectedly found tadpoles in the school's outdoor baby pool, she recognized an unusual opportunity for her students to study pond life up close. By following the tadpoles' development, students learned about frogs, life cycles, habitats. (Contains 1 resource.)

  1. Cascades frog conservation assessment

    Treesearch

    Karen Pope; Catherine Brown; Marc Hayes; Gregory Green; Diane Macfarlane

    2014-01-01

    The Cascades frog (Rana cascadae) is a montane, lentic-breeding amphibian that has become rare in the southern Cascade Range and remains relatively widespread in the Klamath Mountains of northern California. In the southern Cascades, remaining populations occur primarily in meadow habitats where the fungal disease, chytridiomycosis, and habitat...

  2. The Study of Internal Deformation Fields in Borosilicate Glass Using X--Ray Flash Photography

    NASA Astrophysics Data System (ADS)

    Grantham, Stephen; Proud, William; Field, John

    2001-06-01

    Studying the ballistic performance of brittle materials such as borosilicate glass is of particular interest in fields such as transparent armour plating, security glazing and blast-proof windows. Here we extend studies already carried out on the response of borosilicate glass to rod impacts^1 by using flash X-rays to look at the damage occurring behind the damage front. Measurements such as this are impossible using conventional high speed cameras due to optical opacity caused by damage. The new technique of 3--dimensional digital flash X-ray speckle photography, which has been successfully applied to polyester^2 and sand^3 specimens is also utilised. The technique involves seeding the specimen with a layer of lead filings and then taking flash X-ray images before and during an impact event. Digital cross-correlation can then be used to make measurements of the internal displacements occurring throughout the specimen. Using a stereoscopic geometry the out-of-plane displacements can also be determined and a full 3--dimensional displacement map constructed. In this paper these two powerful and complementary techniques are used to study the ballistic response of a borosilicate glass sample. ^1Bourne, N.K., Forde, L.C., Millet, J.C.F., Field, J.F., Impact and Penetration of a Borosilicate Glass, J.Phys.IV FRANCE Colloq. C3, 7 (1997), pp 157-162. ^2Synnergren, P., Goldrein, H.T., Dynamic Measurements of Internal Three-Dimensional Displacement Fields with Digital Speckle Photography and Flash X--Rays, Applied Optics 38 (1999) pp 5956-5961. ^3Grantham, S.G., Proud, W.G., Goldrein, H.T., Field, J.F., The Study of Internal Deformation Fields in Granular Materials Using 3--D Digital X--Ray Flash Photography, Laser Interferometry X, Proc. SPIE 4101 (2000) pp 321-328.

  3. Deriving 3D coseismic deformation field by combining GPS and InSAR data based on the elastic dislocation model

    NASA Astrophysics Data System (ADS)

    Song, Xiaogang; Jiang, Yu; Shan, Xinjian; Qu, Chunyan

    2017-05-01

    The density of GPS measurements is usually one of the key issues in resolving 3-D coseismic deformation field from integrating GPS and Interferometric Synthetic Aperture Radar (InSAR) measurements with pure mathematic interpolation methods An approach that combines the elastic dislocation model with the Best Quadratic Unbiased Estimator (BQUE) or a robust estimation method named IGG (Institute of Geodesy and Geophysics) is proposed to reconstruct 3-D coseismic deformation field, in which only a small amount of GPS data is needed to produce a reasonable initial 3-D coseismic deformation. Then the BQUE and IGG are used to weight the InSAR and GPS measurements to avoid computational issues caused by the negative variance problem and to decrease the impact from gross errors. The Wenchuan earthquake is used to test the proposed method. We find that the developed method makes it possible to use only a few GPSs and InSAR data to recover the 3-D coseismic deformation field, which offers extensive future usage for measuring earthquake deformation, particularly in some tectonically active regions with sparse GPS measurements.

  4. Controllable deformation of salt water-filled carbon nanotubes using an electric field with application to molecular sieving.

    PubMed

    Ye, Hongfei; Zheng, Yonggang; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen

    2016-08-05

    Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units.

  5. Controllable deformation of salt water-filled carbon nanotubes using an electric field with application to molecular sieving

    NASA Astrophysics Data System (ADS)

    Ye, Hongfei; Zheng, Yonggang; Zhang, Zhongqiang; Zhang, Hongwu; Chen, Zhen

    2016-08-01

    Precisely controlling the deformation of carbon nanotubes (CNTs) has practical application in the development of nanoscale functional devices, although it is a challenging task. Here, we propose a novel method to guide the deformation of CNTs through filling them with salt water and applying an electric field. With the electric field along the axial direction, the height of CNTs is enlarged by the axial electric force due to the internal ions and polar water molecules. Under an electric field with two mutually orthogonal components, the transverse electric force could further induce the bending deformation of CNTs. Based on the classical rod and beam theories, two mechanical models are constructed to verify and quantitatively describe the relationships between the tension and bending deformations of CNTs and the electric field intensity. Moreover, by means of the electric field-driven tension behavior of CNTs, we design a stretchable molecular sieve to control the flow rate of mixed gas and collect a single high-purity gas. The present work opens up new avenues in the design and fabrication of nanoscale controlling units.

  6. Fundamental Experiment to Determine Escape Countermeasures for Frogs Falling into Agricultural Canals

    NASA Astrophysics Data System (ADS)

    Watabe, Keiji; Mori, Atsushi; Koizumi, Noriyuki; Takemura, Takeshi

    Frogs often drown in agricultural canals with deep concrete walls, which are installed commonly in paddy fields after land improvement projects in Japan, because they cannot escape after falling into the canal. Therefore, countermeasures that enable frogs to escape from canals are required in some rural areas. An experimental canal with partially sloped walls was used as an escape countermeasure to investigate the preferable angle of slope for the walls, water depth and flow velocity that enables Tokyo Daruma Pond Frogs (Rana porosa porosa), which have no adhesive discs, to easily escape. Walls with slopes of 30-45 degrees allowed 50-60% of frogs to escape from the experimental canals, frogs especially easily climbed the 30 degree sloped walls. When the water depth was 5 cm or flow velocity was greater than 20 cm/s, approximately 80% of the frogs moved downstream and reached the sloped walls because the frogs' toes did not reach the bottom of the canal. However, if the depth was 2 cm and the flow velocity was 5 cm/s, only 4% of the frogs climbed the sloped walls because they could move freely. The frogs appeared to not be good at long-distance swimming and could not remain a long-time under running water. Therefore, walls sloped less than 30 degrees and control of both water depth and flow velocity appears important for enabling frogs to easily escape from canals.

  7. High temperature and deformation field measurements at the vicinity of dynamically growing shear bands

    SciTech Connect

    Rosakis, A.J.; Ravichandran, G.; Zhou, M.

    1995-12-31

    The phenomenon of dynamic initiation and propagation of adiabatic shear bands is experimentally and numerically investigated. Pre-notched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch tip and propagate rapidly in a direction nearly parallel to the direction of the impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high-speed infrared detector system. The materials studied are C-300 (a maraging steel) and Ti - 6 Al - 4 V alloy. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 600{degrees}C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by the Ti - 6Al - 4V alloy. Deformation fields around the propagating shear bands are recorded using high-speed photography. Shear band speeds are found to strongly depend on impact velocities, and are as high as 1200 m/s for C-300 steels. Finite Element simulations of the experiments are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high-speed infrared detectors and high-speed photography.

  8. Near-Field Deformation Associated with the M6.0 South Napa Earthquake Surface Rupture

    NASA Astrophysics Data System (ADS)

    Brooks, B. A.; Hudnut, K. W.; Glennie, C. L.; Ericksen, T.

    2014-12-01

    We characterize near-field deformation associated with the surface rupture of the M6.0 South Napa earthquake from repeat mobile laser scanning (MLS) surveys. Starting the day after the main shock, we operated, sometime simultaneously, short (~75 m range) and medium (~400m range) range laser scanners on a truck or backpack. We scanned most of the length of the principal and secondary surface ruptures at speeds less than 10 km/hr. Scanning occurred primarily in either suburban subdivisions or cultivated vineyards of varying varietals with differing leaf patterns and stages of maturity. Spot-spacing is dense enough (100s of points/m^2) to permit creation of 10-25cm digital elevation models of much of the surface rupture. Scanned features of the right-lateral rupture include classic mole tracks through a variety of soil types, en echelon cracks, offset vine rows, and myriad types of pavement-related deformation. We estimate coseismic surface displacements ranging from 5 to 45 cm by examining offset cultural features and vine rows and by comparing the MLS data with preexisting airborne laser scans from 2003 using point-cloud and solid-modeling methodologies. Additionally, we conducted repeat MLS scans to measure the magnitude and spatial variation of fault afterslip, exceeding 20 cm in some places, particularly in the southern portion of the rupture zone. We anticipate these data sets, in conjunction with independently collected ground-based alinement arrays and space-based geodetic data will contribute significant insight into topics of current debate including assessing the most appropriate material models for shallow fault zones and how shallow and deeper fault slip relate to one another.

  9. Nuclear deformation in the A ≈100 region: Comparison between new masses and mean-field predictions

    NASA Astrophysics Data System (ADS)

    de Roubin, A.; Atanasov, D.; Blaum, K.; George, S.; Herfurth, F.; Kisler, D.; Kowalska, M.; Kreim, S.; Lunney, D.; Manea, V.; Minaya Ramirez, E.; Mougeot, M.; Neidherr, D.; Rosenbusch, M.; Schweikhard, L.; Welker, A.; Wienholtz, F.; Wolf, R. N.; Zuber, K.

    2017-07-01

    An extension of the atomic mass surface in the region A ≈100 was performed via measurements of the Sr-102100 and Rb-102100 masses with the ion-trap spectrometer ISOLTRAP at CERN-ISOLDE, including the first direct mass determination of 102Sr and Rb,102101. These measurements confirm the continuation of the region of deformation with the increase of neutron number, at least as far as N =65 . To interpret the deformation in the strontium isotopic chain and to determine whether an onset of deformation is present in heavier krypton isotopes, a comparison is made between the experimental values and mean-field and beyond mean-field results available in the literature. To complete this comparison Hartree-Fock-Bogoliubov calculations for even and odd isotopes were performed, illustrating the competition of nuclear shapes in the region.

  10. Unsupervised 4D myocardium segmentation with a Markov Random Field based deformable model.

    PubMed

    Cordero-Grande, L; Vegas-Sánchez-Ferrero, G; Casaseca-de-la-Higuera, P; San-Román-Calvar, J Alberto; Revilla-Orodea, Ana; Martín-Fernández, M; Alberola-López, C

    2011-06-01

    A stochastic deformable model is proposed for the segmentation of the myocardium in Magnetic Resonance Imaging. The segmentation is posed as a probabilistic optimization problem in which the optimal time-dependent surface is obtained for the myocardium of the heart in a discrete space of locations built upon simple geometric assumptions. For this purpose, first, the left ventricle is detected by a set of image analysis tools gathered from the literature. Then, the segmentation solution is obtained by the Maximization of the Posterior Marginals for the myocardium location in a Markov Random Field framework which optimally integrates temporal-spatial smoothness with intensity and gradient related features in an unsupervised way by the Maximum Likelihood estimation of the parameters of the field. This scheme provides a flexible and robust segmentation method which has been able to generate results comparable to manually segmented images for some derived cardiac function parameters in a set of 43 patients affected in different degrees by an Acute Myocardial Infarction. Copyright © 2011 Elsevier B.V. All rights reserved.

  11. Direct measurement of strain field evolution during dynamic deformation of an energetic material

    SciTech Connect

    Asay, B.W.; Henson, B.F.; Dickson, P.M.; Fugard, C.S.; Funk, D.J.

    1997-09-01

    The authors previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. They have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  12. Numerical validation of velocity gradient tensor particle tracking velocimetry for highly deformed flow fields

    NASA Astrophysics Data System (ADS)

    Ishikawa, Masa-aki; Murai, Yuichi; Yamamoto, Fujio

    2000-06-01

    Particle tracking velocimetry (PTV) has recently been recognized as quite an effective engineering research tool for understanding multi-dimensional fluid flow structures. There are, however, still a number of unsettled problems in the practical use of PTV, i.e. the lack of generality of the PTV algorithm for various types of flows and the measurement uncertainty with respect to spatial resolution. The authors have developed a generalized PTV algorithm named the velocity gradient tensor (VGT) method in order to accurately track the tracer particles in a flow field with strong local deformation rates. The performance of the VGT method has already been examined for several simple flow fields, such as linear shearing and Taylor-Green vortex flows. In this paper, the applicability of the VGT method for complicated flows, which include a wide dynamic range in wavenumber, is quantitatively examined by simulation of Rankine vortex flows, Karman vortex-shedding flows around a rectangular cylinder and homogeneous turbulent flows, which are numerically solved by using the unsteady Navier-Stokes equations. The results show that the VGT technique, using only two frames to estimate velocity, performs better than does the four-frame PTV technique and has a remarkably higher tracking performance than those of typical conventional PTV algorithms.

  13. Direct measurement of strain field evolution during dynamic deformation of an energetic material

    NASA Astrophysics Data System (ADS)

    Asay, B. W.; Henson, B. F.; Dickson, P. M.; Fugard, C. S.; Funk, D. J.

    1998-07-01

    We previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. We have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  14. Direct Measurement of Strain Field Evolution During Dynamic Deformation of an Energetic Material

    NASA Astrophysics Data System (ADS)

    Asay, B. W.; Henson, B. F.; Funk, D. J.

    1997-07-01

    We previously reported results showing displacement fields (at a single instant in time) on the unconfined surface of an explosive during deformation using white light speckle photography. We have now successfully obtained similar data in confined samples showing the evolution in time of the strain field using laser-induced fluorescence speckle photography. A modified data analysis technique using methods borrowed from particle image velocimetry was used in conjunction with an eight frame electronic CCD camera. For these tests, projectiles of varying shape were fired into an explosive sample. Localization of strain was observed in all cases and was found to be a strong function of the projectile shape, with ignition occurring in those cases where shear appears to play a dominant role. Results from this and continuing studies provide experimental evidence for strain localization, and for the first time allow the direct comparison to computer model predictions. The data are also being used in the design of more realistic and reliable constitutive models.

  15. Cricket frogs maintain body hydration and temperature near levels allowing maximum jump performance.

    PubMed

    Walvoord, Mark E

    2003-01-01

    One goal of this study was to determine the combination of hydration and temperature in the northern cricket frog Acris crepitans that allowed maximum jump distance in the laboratory. Second, environmental variables in the field were measured to determine the best predictor(s) of mean body temperature and hydration and to determine whether frogs maintain levels of temperature and hydration yielding maximum jump distance. Laboratory data revealed that hydration and the hydration-temperature interaction significantly affected jump performance. Frogs at 95% and 85% hydration jumped significantly better than frogs at 75% hydration, but frogs at 95% hydration at 15 degrees C jumped significantly poorer than those at 95% hydration at 30 degrees C. Animals at 85% hydration at 30 degrees C and 85% hydration at 15 degrees C jumped just as well as those at 95% hydration at 30 degrees C. Mean body temperature of 55 frogs in the field was 28.0 degrees C, and hydration was 97.4%. Sky condition (sunny, cloudy, or partly cloudy) was the best predictor of frog hydration, and air temperature was the best predictor of frog body temperature. Cricket frogs in the field maintain a hydration and temperature near those found to yield maximum jump distances in laboratory trials. This may be a behavioral adaptation to allow maximum jump distance during predator avoidance.

  16. Importance of the temperature field and its uncertainties in modeling ductile deformation of the southern California lithosphere

    NASA Astrophysics Data System (ADS)

    Thatcher, W. R.; Chapman, D. S.; Williams, C. F.; Hearn, E. H.

    2015-12-01

    Temperature is arguably the most important parameter controlling ductile deformation in tectonically active regions. Laboratory measurements at lower crust and upper mantle conditions define the mechanisms controlling ductile deformation and constrain quantitative rules relating stress and strain rate. Exhumed ductily deformed rocks reveal the micromechanics of deformation, supplying ground truth that can be compared with lab results. However, even if the mechanism and ductile deformation rules are accepted at face value, strain rates are exquisitely dependent on temperature. Here we critically assess observational data relevant to constraining the southern California lithospheric temperature field. Our goal is to improve estimates of the 3D temperature field and its real uncertainties and apply them to regional deformation modeling. We use a phased approach to estimating geotherms, beginning with simple 1D steady state conductive models. We identify the most important parameters and disaggregate them, separately examining the effects of varying radiogenic heat source concentration, rock type, crust and lithosphere thickness and asthenosphere solidus. We assess geotherm uncertainties by assigning realistic error bounds on all input quantities, propagate these uncertainties by Monte Carlo sampling and determine probability density functions for the geotherm. We find that although other parameter uncertainties contribute, variability in heat sources produces the largest variation in model-predicted geotherms. Because heat production depends strongly on rock type, better characterization of crustal lithology using refined seismic imaging results now becoming available beneath southern California is likely to produce the largest improvements in thermal models. Nonetheless, substantial uncertainty will remain, arguing for adoption of one or a few standard thermal models as common starting points for regional deformation modeling in southern California and elsewhere.

  17. Pesticide residues in two frog species in a paddy agroecosystem in Palakkad district, Kerala, India.

    PubMed

    Kittusamy, Ganesan; Kandaswamy, Chandrasekar; Kandan, Nambirajan; Subramanian, Muralidharan

    2014-12-01

    Pesticides residues were quantified in 109 frogs comprising two species (Fejervarya limnocharis and Hoplobatrachus crassus) from organic and conventional paddy farms in Kerala, India. Seven frogs from conventional but none from the organic farms revealed deformities. Levels of total Organochlorines (OCs) (33.22 ng/g) and Synthetic Pyrethroid, Fenvalerate-II (26.91/42.15 ng/g) in deformed F. limnocharis and H. crassus were significantly greater than in healthy frogs. Among OCs in healthy frogs, traces of γ (gamma)-HCH (hexachlorocyclohexane) (2.12 ng/g) were found only in F. limnocharis from organic farm. Among Organophosphates, Phorate (1.02 ng/g) and Quinalphos (2.62 ng/g) were present in traces in deformed F. limnocharis, while Parathion ethyl (1.02 ng/g) was detected in deformed H. crassus. The data indicate that the high level of pesticides may have contributed to the deformity of frogs. Therefore, an elaborative study will be essential to conserve amphibians in India.

  18. The Field Relevance of NHTSA's Oblique Research Moving Deformable Barrier Tests.

    PubMed

    Prasad, Priya; Dalmotas, Dainius; German, Alan

    2014-11-01

    A small overlap frontal crash test has been recently introduced by the Insurance Institute for Highway Safety in its frontal rating scheme. Another small overlap frontal crash test is under development by the National Highway Traffic Safety Administration (NHTSA). Whereas the IIHS test is conducted against a fixed rigid barrier, the NHTSA test is conducted with a moving deformable barrier that overlaps 35% of the vehicle being tested and the angle between the longitudinal axis of the barrier and the longitudinal axis of the test vehicle is 15 degrees. The field relevance of the IIHS test has been the subject of a paper by Prasad et al. (2014). The current study is aimed at examining the field relevance of the NHTSA test. The field relevance is indicated by the frequency of occurrence of real world crashes that are simulated by the test conditions, the proportion of serious-to-fatal real world injuries explained by the test condition, and rates of serious injury to the head, chest and other body regions in the real world crashes resembling the test condition. The database examined for real world crashes is NASS. Results of the study indicate that 1.4% of all frontal 11-to-1 o'clock crashes are simulated by the test conditions that account for 2.4% to 4.5% of all frontal serious-to-fatal (MAIS3+F) injuries. Injury rates of the head and the chest are substantially lower in far-side than in near-side frontal impacts. Crash test ATD rotational responses of the head in the tests overpredict the real world risk of serious-to-fatal brain injuries.

  19. Microhydrodynamics of deformable particles: surprising responses of drops and vesicles to uniform electric field or shear flow

    NASA Astrophysics Data System (ADS)

    Vlahovska, Petia

    2015-11-01

    Particle motion in a viscous fluid is a classic problem that continues to surprise researchers. In this talk, I will discuss some intriguing, experimentally-observed behaviors of droplets and giant vesicles (cell-size lipid membrane sacs) in electric or flow fields. In a uniform electric field, a droplet deforms into an ellipsoid that can either be steadily tilted relative to the applied field direction or undergo unsteady motions (periodic shape oscillations or irregular flipping); a spherical vesicle can adopt a transient square shape or reversibly porate. In a steady shear flow, a vesicle can tank-tread, tumble or swing. Theoretical models show that the nonlinear drop dynamics originates from the interplay of Quincke rotation and interface deformation, while the vesicle dynamics stems from the membrane inextensibility. The practical motivation for this research lies in an improved understanding of technologies that rely on the manipulation of drops and cells by flow or electric fields.

  20. Implementation and Evaluation of the Virtual Fields Method: Determining Constitutive Model Parameters From Full-Field Deformation Data.

    SciTech Connect

    Kramer, Sharlotte Lorraine Bolyard; Scherzinger, William M.

    2014-09-01

    The Virtual Fields Method (VFM) is an inverse method for constitutive model parameter identication that relies on full-eld experimental measurements of displacements. VFM is an alternative to standard approaches that require several experiments of simple geometries to calibrate a constitutive model. VFM is one of several techniques that use full-eld exper- imental data, including Finite Element Method Updating (FEMU) techniques, but VFM is computationally fast, not requiring iterative FEM analyses. This report describes the im- plementation and evaluation of VFM primarily for nite-deformation plasticity constitutive models. VFM was successfully implemented in MATLAB and evaluated using simulated FEM data that included representative experimental noise found in the Digital Image Cor- relation (DIC) optical technique that provides full-eld displacement measurements. VFM was able to identify constitutive model parameters for the BCJ plasticity model even in the presence of simulated DIC noise, demonstrating VFM as a viable alternative inverse method. Further research is required before VFM can be adopted as a standard method for constitu- tive model parameter identication, but this study is a foundation for ongoing research at Sandia for improving constitutive model calibration.

  1. GPS measurements of near-field deformation along the southern Dead Sea Fault System

    NASA Astrophysics Data System (ADS)

    Al Tarazi, Eid; Abu Rajab, Jafar; Gomez, Francisco; Cochran, William; Jaafar, Rani; Ferry, Matthieu

    2011-12-01

    Analysis of short-term deformation along the southern part of Dead Sea Fault (DSF) provides a systematic view of kinematics this part of the continental transform. The southern DSF consists of two principal segments: the Wadi Araba and Jordan Valley faults. In addition to other regional continuous GPS data, this study uses new data from 25 survey sites and 4 continuous GPS stations in Jordan for improved near-field observations. Resulting velocities are reported with 1-σ uncertainties ranging from 0.4-1.0 mm/yr. Application of elastic dislocation models yields estimates of slip rates for Wadi Araba and Jordan Valley faults are 4.9 ± 0.4 mm/yr and 4.7 ± 0.4 mm/yr, respectively. Modeling also suggests different depths of effective fault locking with 15 ± 5 km and 8 ± 5 km for the Wadi Araba and Jordan Valley faults, respectively. These slip rates are generally consistent with the upper end of the range of slip rates estimated from late Quaternary geology. Spatial variations in effective fault locking generally correspond with a heterogeneous mantle lithosphere. A similar observation can be observed along the southern San Andreas Fault, and this may reflect the influence of heterogeneity in the uppermost mantle on crustal faulting processes.

  2. Characterization of a MEMS deformable mirror by far field intensity evaluation

    NASA Astrophysics Data System (ADS)

    Greiner, Cherry; Finn, Susanna; Choi, Stacey; Doble, Nathan

    2013-03-01

    The performance of an adaptive optics (AO) system is typically measured using the wavefront sensor (WFS). However, another method is to use the point spread function (PSF), which is sensitive to scatter, does not act as a low pass filter and is not dependent on the WFS calibration. We decided to examine the performance of an AO system built for vision science that employed a micromechanical systems (MEMS) based deformable mirror (DM). Specifically, the MEMS DM consists of 489 actuators, resulting in 163 segments each with individual piston/tip/tilt control. Initial evaluation of the DM with a model eye included determining the ability of the DM to generate individual Zernike polynomials and evaluating the far field PSF to measure wavefront correction performance. For individual Zernike polynomial terms, the DM was found to be capable of correcting the aberration magnitudes expected from previously published human population studies.1, 2 Finally, the DM was used in an AO fundus camera to successfully acquire images of cone photoreceptors in a living human eye. This is part of ongoing work which will incorporate the MEMS DM into both an AO scanning laser ophthalmoscope (SLO) and an AO optical coherence tomography (OCT) system where the form of the PSF at the confocal pinhole/optical fiber is important for optimal imaging.

  3. A persistent scatterer interpolation for retrieving accurate ground deformation over InSAR-decorrelated agricultural fields

    NASA Astrophysics Data System (ADS)

    Chen, Jingyi; Zebker, Howard A.; Knight, Rosemary

    2015-11-01

    Interferometric synthetic aperture radar (InSAR) is a radar remote sensing technique for measuring surface deformation to millimeter-level accuracy at meter-scale resolution. Obtaining accurate deformation measurements in agricultural regions is difficult because the signal is often decorrelated due to vegetation growth. We present here a new algorithm for retrieving InSAR deformation measurements over areas with severe vegetation decorrelation using adaptive phase interpolation between persistent scatterer (PS) pixels, those points at which surface scattering properties do not change much over time and thus decorrelation artifacts are minimal. We apply this algorithm to L-band ALOS interferograms acquired over the San Luis Valley, Colorado, and the Tulare Basin, California. In both areas, the pumping of groundwater for irrigation results in deformation of the land that can be detected using InSAR. We show that the PS-based algorithm can significantly reduce the artifacts due to vegetation decorrelation while preserving the deformation signature.

  4. Pure Ultrasonic Communication in an Endemic Bornean Frog

    PubMed Central

    Arch, Victoria S.; Grafe, T. Ulmar; Gridi-Papp, Marcos; Narins, Peter M.

    2009-01-01

    Huia cavitympanum, an endemic Bornean frog, is the first amphibian species known to emit exclusively ultrasonic (i.e., >20 kHz) vocal signals. To test the hypothesis that these frogs use purely ultrasonic vocalizations for intraspecific communication, we performed playback experiments with male frogs in their natural calling sites. We found that the frogs respond with increased calling to broadcasts of conspecific calls containing only ultrasound. The field study was complemented by electrophysiological recordings from the auditory midbrain and by laser Doppler vibrometer measurements of the tympanic membrane's response to acoustic stimulation. These measurements revealed that the frog's auditory system is broadly tuned over high frequencies, with peak sensitivity occurring within the ultrasonic frequency range. Our results demonstrate that H. cavitympanum is the first non-mammalian vertebrate described to communicate with purely ultrasonic acoustic signals. These data suggest that further examination of the similarities and differences in the high-frequency/ultrasonic communication systems of H. cavitympanum and Odorrana tormota, an unrelated frog species that produces and detects ultrasound but does not emit exclusively ultrasonic calls, will afford new insights into the mechanisms underlying vertebrate high-frequency communication. PMID:19401782

  5. Seismicity and deformation in the Coso Geothermal field from 2000 to 2012

    NASA Astrophysics Data System (ADS)

    Kaven, J. Ole; Hickman, Stephen H.; Davatzes, Nicholas C.

    2015-04-01

    Induced micro-seismicity in geothermal reservoirs, in particular in enhanced geothermal systems (EGS), is an intended byproduct of injection and production, as it often indicates the generation of permeability pathways on either pre-existing or newly generated faults and fractures. The hazard of inducing an earthquake large enough to cause damage to surface structures, however, is not easily avoided and has led to termination of geothermal projects. To explore the physical processes leading to damaging earthquakes, we investigate the evolution of seismicity and the factors controlling the migration, moment release rate, and structure within the seismicity in the Coso Geothermal Field (CGF). The CGF has been in production since the 1980s and includes both naturally occurring geothermal resources and portions of the reservoir that are EGS projects. We report on seismicity in the CGF that has been relocated with high precision double-difference relocation and simultaneous velocity inversion to understand the reservoir compartmentalization, in particular, where boundaries to flow exist both vertically and horizontally. We also calculate moment magnitudes (Mw) from the initial displacement pulse of the seismograms to relate moment directly to the deformation. We find that two distinct compartments form the CGF, which are divided by an aseismic gap that also shows a relatively low Vp/Vs ratio. Further, we find that events with Mw> 3.5 tend to map onto larger fault structures that are imaged by the relocated seismicity. We relate the temporal and spatial migration of moment release rate to the injection and production records in the reservoir by employing a thermo-poro-elastic finite element model in which the compartment boundaries are defined by the seismicity. We find that pore pressure effects alone are not responsible for the migration of seismicity and that poro-elastic and thermo-elastic strain changes can account for more of the observed moment release rate than

  6. Signature of magmatic processes in ground deformation signals from Phlegraean Fields (Italy)

    NASA Astrophysics Data System (ADS)

    Bagagli, Matteo; Montagna, Chiara Paola; Longo, Antonella; Papale, Paolo

    2016-04-01

    Ground deformation signals such as dilatometric and tiltmetric ones, are nowadays well studied from the vulcanological community all over the world. These signals can be used to retrieve information on volcanoes state and to study the magma dynamics in their plumbing system. We compared synthetic signals in the Very Long Period (VLP, 10-2 - 10-1 Hz) and Ultra Long Period (ULP, 10-4 - 10-2 Hz) bands obtained from the simulation of magma mixing in shallow reservoirs ([3],[4]) with real data obtained from the dilatometers and tiltmeters network situated in the Phlegraean Fields near Naples (Italy), in order to define and constrain the relationships between them. Analyses of data from the October 2006 seismic swarm in the area show that the frequency spectrum of the synthetics is remarkably similar to the transient present in the real signals. In depth studies with accurated techniques for spectral analysis (i.e wavelet transform) and application of this method to other time windows have identified in the bandwidth around 10-4Hz (between 1h30m and 2h45m) peaks that are fairly stable and independent from the processing carried out on the full-band signal. These peaks could be the signature of ongoing convection at depth. It is well known that re-injection of juvenile magmas can reactivate the eruption dynamics ([1],[2]), thus being able to define mixing markers and detect them in the ground deformation signals is a relevant topic in order to understand the dynamics of active and quiescent vulcanoes and to eventually improve early-warning methods for impending eruptions. [1] Arienzo, I. et al. (2010). "The feeding system of Agnano-Monte Spina eruption (Campi Flegrei, Italy): dragging the past into present activity and future scenarios". In: Chemical Geology 270.1, pp. 135-147. [2] Bachmann, Olivier and George Bergantz (2008). "The magma reservoirs that feed supereruptions". In: Elements 4.1, pp. 17-21. [3] Longo, Antonella et al. (2012). "Magma convection and mixing

  7. Geodetic Measurements and Numerical Modeling of Deformation at Raft River Geothermal Field, Idaho, U.S.A.

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Feigl, K. L.; Moore, J.; Plummer, M. A.; Warren, I.

    2015-12-01

    To measure time-dependent deformation at the Raft River geothermal field in Cassia County in Southwestern Idaho, we analyze interferometric synthetic aperture radar (InSAR) data acquired between 2006 and 2015 by several satellite missions, including: Envisat, ALOS, TerraSAR-X, and TanDEM-X. The resulting time-series analysis indicates that the deformation began in late 2007, shortly after a 13-megawatt geothermal power plant began commercial production. The rate of deformation appears to be decreasing over time since 2008. The resulting maps of deformation show primarily uplift with some subsidence. The uplift signal is located in an ~8-km-by-5-km area centered near three injection wells that recycle produced brine into the Salt Lake formation, which consists of Miocene-Pliocene lacustrine deposits, volcanic tuffs, and lava flows. Subsidence occurs in an adjacent ~4-km-by-4-km area to the northwest. These two signatures remain in the same location in all of the well-correlated interferometric pairs since 2008. Although all production wells are also located inside the area experiencing uplift, most of them are close to the boundary that separates the two areas, and likely associated with the steeply dipping Bridge Fault zone. We explore the relative roles of thermal (T), and hydrological (H) processes on mechanical deformation (M). To do so, we use finite element based numerical models to calculate the time-dependent deformation field due to thermal contraction/expansion of rock (T-M coupling), and changes in pore pressure (H-M coupling).

  8. Time-series analysis of surface deformation at Brady Hot Springs geothermal field (Nevada) using interferometric synthetic aperture radar

    SciTech Connect

    Ali, S. T.; Akerley, J.; Baluyut, E. C.; Cardiff, M.; Davatzes, N. C.; Feigl, K. L.; Foxall, W.; Fratta, D.; Mellors, R. J.; Spielman, P.; Wang, H. F.; Zemach, E.

    2016-05-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014, by the ERS-2, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada due to extraction of fluids. The long axis of the ~4 km by ~1.5 km elliptical subsiding area coincides with the strike of the dominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, likely associated with damaged regions where fault segments mechanically interact. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing a high permeability conduit to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We also explore mechanisms that could potentially cause the observed deformation, including thermal contraction of rock, decline in pore pressure and dissolution of minerals over time.

  9. Correlations of Surface Deformation and 3D Flow Field in a Compliant Wall Turbulent Channel Flow.

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Zhang, Cao; Katz, Joseph

    2015-11-01

    This study focuses on the correlations between surface deformation and flow features, including velocity, vorticity and pressure, in a turbulent channel flow over a flat, compliant Polydimethylsiloxane (PDMS) wall. The channel centerline velocity is 2.5 m/s, and the friction Reynolds number is 2.3x103. Analysis is based on simultaneous measurements of the time resolved 3D velocity and surface deformation using tomographic PIV and Mach-Zehnder Interferometry. The volumetric pressure distribution is calculated plane by plane by spatially integrating the material acceleration using virtual boundary, omni-directional method. Conditional sampling based on local high/low pressure and deformation events reveals the primary flow structures causing the deformation. High pressure peaks appear at the interface between sweep and ejection, whereas the negative deformations peaks (dent) appear upstream, under the sweeps. The persistent phase lag between flow and deformations are presumably caused by internal damping within the PDMS. Some of the low pressure peaks and strong ejections are located under the head of hairpin vortices, and accordingly, are associated with positive deformation (bump). Others bumps and dents are correlated with some spanwise offset large inclined quasi-streamwise vortices that are not necessarily associated with hairpins. Sponsored by ONR.

  10. Teams Explore the Whole Frog

    ERIC Educational Resources Information Center

    Cessna, Clair E.

    1973-01-01

    Describes the content and organization of a laboratory session in which student teams work on the organs, tissues, and parasites of a pithed frog. The procedure maximizes participation by every student, makes possible the fullest use of each frog, and permits a rather broad study in a limited time. (JR)

  11. Teams Explore the Whole Frog

    ERIC Educational Resources Information Center

    Cessna, Clair E.

    1973-01-01

    Describes the content and organization of a laboratory session in which student teams work on the organs, tissues, and parasites of a pithed frog. The procedure maximizes participation by every student, makes possible the fullest use of each frog, and permits a rather broad study in a limited time. (JR)

  12. Panamanian frog species host unique skin bacterial communities

    PubMed Central

    Belden, Lisa K.; Hughey, Myra C.; Rebollar, Eria A.; Umile, Thomas P.; Loftus, Stephen C.; Burzynski, Elizabeth A.; Minbiole, Kevin P. C.; House, Leanna L.; Jensen, Roderick V.; Becker, Matthew H.; Walke, Jenifer B.; Medina, Daniel; Ibáñez, Roberto; Harris, Reid N.

    2015-01-01

    Vertebrates, including amphibians, host diverse symbiotic microbes that contribute to host disease resistance. Globally, and especially in montane tropical systems, many amphibian species are threatened by a chytrid fungus, Batrachochytrium dendrobatidis (Bd), that causes a lethal skin disease. Bd therefore may be a strong selective agent on the diversity and function of the microbial communities inhabiting amphibian skin. In Panamá, amphibian population declines and the spread of Bd have been tracked. In 2012, we completed a field survey in Panamá to examine frog skin microbiota in the context of Bd infection. We focused on three frog species and collected two skin swabs per frog from a total of 136 frogs across four sites that varied from west to east in the time since Bd arrival. One swab was used to assess bacterial community structure using 16S rRNA amplicon sequencing and to determine Bd infection status, and one was used to assess metabolite diversity, as the bacterial production of anti-fungal metabolites is an important disease resistance function. The skin microbiota of the three Panamanian frog species differed in OTU (operational taxonomic unit, ~bacterial species) community composition and metabolite profiles, although the pattern was less strong for the metabolites. Comparisons between frog skin bacterial communities from Panamá and the US suggest broad similarities at the phylum level, but key differences at lower taxonomic levels. In our field survey in Panamá, across all four sites, only 35 individuals (~26%) were Bd infected. There was no clustering of OTUs or metabolite profiles based on Bd infection status and no clear pattern of west-east changes in OTUs or metabolite profiles across the four sites. Overall, our field survey data suggest that different bacterial communities might be producing broadly similar sets of metabolites across frog hosts and sites. Community structure and function may not be as tightly coupled in these skin symbiont

  13. Full-physics 3D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

    SciTech Connect

    Samluk, Jesse P.; Geiger, Cathleen A.; Weiss, Chester J.; Kolodzey, James

    2015-10-01

    In this article we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell's equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water as a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as 'null lines'. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.

  14. Full-physics 3D heterogeneous simulations of electromagnetic induction fields on level and deformed sea ice

    DOE PAGES

    Samluk, Jesse P.; Geiger, Cathleen A.; Weiss, Chester J.; ...

    2015-10-01

    In this article we explore simulated responses of electromagnetic (EM) signals relative to in situ field surveys and quantify the effects that different values of conductivity in sea ice have on the EM fields. We compute EM responses of ice types with a three-dimensional (3-D) finite-volume discretization of Maxwell's equations and present 2-D sliced visualizations of their associated EM fields at discrete frequencies. Several interesting observations result: First, since the simulator computes the fields everywhere, each gridcell acts as a receiver within the model volume, and captures the complete, coupled interactions between air, snow, sea ice and sea water asmore » a function of their conductivity; second, visualizations demonstrate how 1-D approximations near deformed ice features are violated. But the most important new finding is that changes in conductivity affect EM field response by modifying the magnitude and spatial patterns (i.e. footprint size and shape) of current density and magnetic fields. These effects are demonstrated through a visual feature we define as 'null lines'. Null line shape is affected by changes in conductivity near material boundaries as well as transmitter location. Our results encourage the use of null lines as a planning tool for better ground-truth field measurements near deformed ice types.« less

  15. Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field.

    PubMed

    Tarrío-Saavedra, Javier; González, Cécilia Galindo; Naya, Salvador; López-Beceiro, Jorge; Ponton, Alain

    2017-01-01

    This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling. Image enhancement and then image segmentation (Gaussian mixture modeling) processes were applied to extract features with reliable information of droplets dimensions from optical micrographs. The droplets deformation and relaxation trends were accurately adjusted by the Kohlrausch-Williams-Watts (KWW) function and a mean relaxation time was obtained by fitting the time evolution of geometry parameters. It was found to be proportional to the initial radius of the spherical droplets and was associated to interfacial tension.

  16. Single-domain magnetic nanoparticles in an alternating magnetic field as mediators of local deformation of the surrounding macromolecules

    NASA Astrophysics Data System (ADS)

    Golovin, Yu. I.; Gribanovskii, S. L.; Golovin, D. Yu.; Klyachko, N. L.; Kabanov, A. V.

    2014-07-01

    The forces, deformations, and stresses generated in macromolecules attached to single-domain magnetic nanoparticles under the influence of a low-frequency (nonheating) magnetic field have been analyzed analytically and numerically. It has been shown that, in bioactive macromolecules, an alternating magnetic field with an induction of 0.1-1.0 T and a circular frequency of ≲104 s-1 can induce forces up to several hundred piconewtons, absolute deformations up to a few tens of nanometers, as well as compressive and shear stresses exceeding 107 Pa. These mechanical stimuli are sufficient for a significant change of interatomic distances in active centers, conformation of macromolecules, and even a breaking of some bonds, which makes it possible to develop a new technological platform for targeted delivery of drugs, remote control of their activity, and cancer-cell destruction.

  17. Statistical Modeling Applied to Deformation-Relaxation Processes in a Composite Biopolymer Network Induced by Magnetic Field

    PubMed Central

    Tarrío-Saavedra, Javier; González, Cécilia Galindo; Naya, Salvador; López-Beceiro, Jorge

    2017-01-01

    This study investigated a methodology based on image processing and statistics to characterize and model the deformation upon controlled and uniform magnetic field and the relaxation under zero field of droplets observed in aqueous solutions of sodium alginate incorporating magnetic maghemite nanoparticles stabilized by adsorption of citrate ions. The changes of droplet geometry were statistically analyzed using a new approach based on the data obtained from optical microscopy, image processing, nonlinear regression, evolutionary optimization, analysis of variance and resampling. Image enhancement and then image segmentation (Gaussian mixture modeling) processes were applied to extract features with reliable information of droplets dimensions from optical micrographs. The droplets deformation and relaxation trends were accurately adjusted by the Kohlrausch-Williams-Watts (KWW) function and a mean relaxation time was obtained by fitting the time evolution of geometry parameters. It was found to be proportional to the initial radius of the spherical droplets and was associated to interfacial tension. PMID:28081239

  18. Lithobates sylvaticus (wood frog)

    USGS Publications Warehouse

    Fuller, Pam

    2016-01-01

    A single specimen found southwest of Hattiesburg in Timberton (31.270391oN, 89.327675oW; WGS 84). 23 July 2015. Gary, Kat, and Ron Lukens. Verifi ed by Kenneth Krysko, Florida Museum of Natural History (UF-Herpetology 176455). This species has never been recorded from the state of Mississippi before (Dodd 2013. Frogs of the United States and Canada – Volume 2. John Hopkins University Press, Baltimore, Maryland. 982 pp.). According to Dodd (2013), the closest population is located in east central Alabama, approximately 400 km to the northeast, as documented by Davis and Folkerts (1986. Brimleyana 12:29-50).

  19. Effect of interfacial slip on the deformation of a viscoelastic drop in uniaxial extensional flow field

    NASA Astrophysics Data System (ADS)

    Das, Sayan; Mandal, Shubhadeep; Som, S. K.; Chakraborty, Suman

    2017-03-01

    The effect of interfacial slip on the deformation of a viscoelastic droplet, suspended in another viscoelastic medium, in the presence of a uniaxial extensional flow, is studied analytically. Using the Oldroyd-B constitutive relation, the Stokes flow problem is solved in the limit of a small capillary number and small Deborah number. Experimentally observed interfacial velocity slip is incorporated using a Navier slip boundary condition. The interfacial slip significantly reduces the magnitude of droplet deformation when the droplet has larger viscosity as compared with the suspending phase. The droplet shape becomes less ellipsoidal in the presence of slip. The effect of slip diminishes for low viscosity droplets. Slip effectively weakens the dependence of the droplet deformation on the droplet to medium viscosity ratio. The viscoelasticity of the suspending phase plays a dominant role on the droplet deformation as compared with the viscoelasticity of the droplet phase when there is velocity slip at the droplet surface. The interfacial slip aids the viscoelasticity of the suspending phase in deforming the droplet, while the effect of viscoelasticity of the droplet phase is suppressed by the interfacial slip.

  20. Deformation at Brady Hot Springs (Nevada) geothermal field measured by time series analysis of InSAR data

    NASA Astrophysics Data System (ADS)

    Ali, S. T.; Davatzes, N. C.; Feigl, K. L.; Wang, H. F.; Foxall, W.; Mellors, R. J.; Akerley, J.; Spielman, P.; Zemach, E.

    2014-12-01

    We analyze interferometric synthetic aperture radar (InSAR) data acquired between 1997 and 2014 (by the ERS, Envisat, ALOS and TerraSAR-X/TanDEM-X satellite missions) to measure and characterize time-dependent deformation at the Brady Hot Springs geothermal field in Western Nevada due to net extraction of fluids. The long axis of the ~4 km by ~1.5 km oval shaped subsiding region coincides with the strike of the predominant normal fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. These smaller features are spatially associated with the intersections and overlaps of some of the mapped fault segments. This type of signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. To model the deformation, we explore several different observable quantities, including the spatial derivative of the range change (dimensionless), and the (unwrapped) range change (in mm). The results from inverse modeling suggest that the deformation is a result of compaction associated with a decline in pore-fluid pressure. This phenomenon occurs in shallow lithologic units and/or highly damaged regions where fault segments mechanically interact. Such damaged zones are expected to be vertically extensive along the faults, providing a high permeability conduit to the deep reservoir tapped by production wells. Using time series analysis, we test the hypothesis that changes in the net rate of geothermal production drive the observed deformation.

  1. Drainage ditches facilitate frog movements in a hostile landscape

    USGS Publications Warehouse

    Mazerolle, M.J.

    2005-01-01

    Ditches are common in landscapes influenced by agricultural, forestry, and peat mining activities, and their value as corridors remains unassessed. Pond-breeding amphibians can encounter hostile environments when moving between breeding, summering, or hibernation sites, and are likely to benefit from the presence of ditches in the landscape. Within a system consisting of ditch networks in bogs mined for peat in eastern New Brunswick, Canada, I quantified the breeding, survival, and movements of green frogs (Rana clamitans melanota) in drainage ditches and also surveyed peat fields. Frogs rarely ventured on peat fields and most individuals frequented drainage ditches containing water, particularly in late summer. Though frogs did not breed in ditches, their survival rate in ditches was high (88%). Ditches did not hinder frog movements, as frogs moved independently of the current. Results indicate that drainage ditches containing water enable some movements between habitats isolated by peat mining, in contrast to peat surfaces, and suggest they function as amphibian movement corridors. Thus, such drainage ditches may mitigate the effects of peat extraction on amphibian populations. At the very least, these structures provide an alternative to hostile peat surfaces. This study highlights that small-scale corridors are potentially valuable in population dynamics. ?? Springer 2005.

  2. Synergism between trematode infection and pesticide exposure: a link to amphibian limb deformities in nature?

    PubMed

    Kiesecker, Joseph M

    2002-07-23

    The apparently rapid increase in the prevalence of amphibian limb deformities has led to substantial interest from ecologists and public health professionals. Hypotheses proposed to explain the deformities fall into two broad categories: chemical contaminants and trematode infection. Although there are convincing experimental demonstrations that certain factors can lead to some deformities, the causes for recent increases in amphibian malformation remain controversial. Moreover, no experimental studies on amphibian deformities have been conducted in the field, and no studies have attempted to examine the synergistic effects of trematode infection and exposure to chemical contaminants. Here, I present the results of field and laboratory experiments that link increased trematode infection, and increased limb deformities, to pesticide exposure. Field experiments conclusively demonstrated that exposure to trematode infection was required for the development of limb deformities in wood frogs, Rana sylvatica. However, deformities were more common at sites adjacent to agricultural runoff. Laboratory experiments corroborated the association between pesticide exposure and increased infection with pesticide-mediated immunocompetency as the apparent mechanism. Given the conservative contaminant exposure levels used [Environmental Protection Agency (EPA) drinking water standards] and the widespread use of many pesticides, these negative impacts may help to explain pathogen-mediated amphibian declines in many regions.

  3. The effect of radiation modification and of a uniform magnetic field on the deformation properties of polymer composite blends

    NASA Astrophysics Data System (ADS)

    Reinholds, I.; Kalkis, V.; Maksimov, R. D.; Zicans, J.; Meri, R. Merijs

    2011-11-01

    An experimental study of radiation-modified blends of high-density polyethylene with a chlorinated polyethylene exposed to a constant magnetic field with induction equal to 0.7, 1.0, 1.4, and 1.8 T is presented. A preliminary gamma irradiation has been performed with absorbed doses equal to 50, 100, and 200 kGy. The main attention is devoted to the investigation of deformation (elastic and viscoelastic) properties of the material. Data showing the effect of the absorbed dose of gamma irradiation and the induction of magnetic field on the elastic modulus and creep of the material under a constant stress are obtained.

  4. Does intraplate brittle deformation indicate far-field stress signals? A case study of Central Europe

    NASA Astrophysics Data System (ADS)

    Navabpour, Payman; Kley, Jonas; Le Breton, Eline; van Hinsbergen, Douwe J. J.; Ustaszewski, Kamil

    2017-04-01

    Even though Central Europe has been located within a plate interior since the end of the Variscan orogeny, its intracontinental basins and highs recorded a succession of different tectonic regimes throughout the Mesozoic and Cenozoic, which were coeval with events at distant plate margins. A long Triassic-Cretaceous period of weak subsidence with intermittent extension was followed by NNE-SSW contraction in the Late Cretaceous-Paleocene. Renewed extension led to the formation of the Cenozoic Rift System and eventually evolved to the present-day variable stress regimes with a consistent NW-SE-oriented maximum horizontal shortening, SHmax. The detailed knowledge of this evolution relies on exhaustive lithostratigraphy and geochronological datasets, as well as on reconstruction of successive states of paleostress that controlled the formation and/or inversion of intracontinental basins. In combination, these data provide an excellent opportunity of linking the intracontinental deformation to the lithospheric plate boundary kinematics. Regional-scale analysis of fault kinematics in Central Europe unveiled a succession of consistent stress states for the crystalline basement and sedimentary cover of the brittle crust. These states of stress include a post-Triassic normal faulting regime with NE-SW-trending σ3 axis, strike-slip and thrust faulting regimes with NNE-SSW-trending σ1 axis, supposedly of Late Cretaceous age, and two younger events of normal and strike-slip faulting regimes with NW-SE-trending σ3 and σ1 axes, respectively. In this study, we report on the first attempts of linking the central European intraplate kinematics to changes in relative motion between the plates. The integration of stress fields with plate boundary kinematics suggests that the Late Cretaceous contraction may be explained by a change in African plate motion with respect to Eurasia from SE-directed sinistral transform to NNE-directed convergence. The reorientation of contraction to

  5. Leopard frog and wood frog reproduction in Colorado and Wyoming

    USGS Publications Warehouse

    Corn, Paul Stephen; Livo, Lauren J.

    1989-01-01

    Between 1978 and 1988, we recorded reproductive information from populations of ranid frogs in Colorado and Wyoming. Egg masses from five plains and montane populations of northern leopard frogs (Rana pipiens) contained 645-6272 eggs (x̄ = 3045, N = 68 egg masses). In two montane populations of wood frogs (Rana sylvatica) numbers of eggs per egg mass varied from 711-1248 (x̄ = 876, N = 15) and probably were equal to total clutch size. Mean hatching success was 90% in egg masses from one R. sylvatica population and ranged from 70% to 99% in R. pipiens egg masses. Rana pipiens egg masses from one location were assigned to three overlapping size distributions, which we believe reflects the underlying age structure of female frogs.

  6. Investigation of the longitudinal magnetic field effect on dynamic response of viscoelastic graphene sheet based on sinusoidal shear deformation theory

    NASA Astrophysics Data System (ADS)

    Arani, A. Ghorbanpour; Jalaei, M. H.

    2017-02-01

    This research aims to investigate the influence of a longitudinal magnetic field on the dynamic response of single-layered graphene sheet (SLGS) resting on viscoelastic foundation based on the nonlocal sinusoidal shear deformation theory. The present model is capable of capturing both small scale effect and transverse shear deformation effects of nanoplate, and does not require shear correction factors. The material properties of graphene sheet are assumed orthotropic viscoelastic using Kelvin-Voigt model. Utilizing Hamilton's principle governing equations of motion are derived and solved analytically. The parametric study is conducted, focusing on the remarkable effects of the magnetic field, structural damping, stiffness and damping coefficient of the foundation, nonlocal parameter, aspect ratio and length to thickness ratio on the dynamic response of the SLGS. Results indicate that the longitudinal magnetic field exerted on the SLGS decreases the amplitude of dynamic response. In addition, it is observed that the magnetic field effect on the dynamic response is more distinguished as the nonlocal parameter increases while by increasing the foundation and structural damping coefficients, this effect diminishes. The results of this study can be used in design and manufacturing of nanomechanical devices in the presence of magnetic field as a parametric controller.

  7. Implementing ground surface deformation tools to characterize field-scale properties of a fractured aquifer during a short hydraulic test

    NASA Astrophysics Data System (ADS)

    Schuite, Jonathan; Longuevergne, Laurent; Bour, Olivier; Boudin, Frédérick; Durand, Stéphane

    2016-04-01

    In naturally fractured reservoirs, fluid flow is governed by the structural and hydromechanical properties of fracture networks or conductive fault zones. In order to ensure a sustained exploitation of resources or to assess the safety of underground storage, it is necessary to evaluate these properties. As they generally form highly heterogeneous and anisotropic reservoirs, fractured media may be well characterized by means of several complementary experimental methods or sounding techniques. In this framework, the observation of ground deformation has been proved useful to gain insight of a fractured reservoir's geometry and hydraulic properties. Commonly, large conductive structures like faults can be studied from surface deformation from satellite methods at monthly time scales, whereas meter scale fractures have to be examined under short-term in situ experiments using high accuracy intruments like tiltmeters or extensometers installed in boreholes or at the ground's surface. To the best of our knowledge, the feasability of a field scale (~ 100 m) characterization of a fractured reservoir with geodetic tools in a short term experiment has not yet been addressed. In the present study, we implement two complementary ground surface geodetic tools, namely tiltmetry and optical leveling, to monitor the deformation induced by a hydraulic recovery test at the Ploemeur hydrological observatory (France). Employing a simple purely elastic modeling approach, we show that the joint use of time constraining data (tilt) and spatially constraining data (vertical displacement) makes it possible to evaluate the geometry (dip, root depth and lateral extent) and the storativity of a hydraulically active fault zone, in good agreement with previous studies. Hence we demonstrate that the adequate use of two complementary ground surface deformation methods offer a rich insight of large conductive structure's properties using a single short term hydraulic load. Ground surface

  8. Sediment budget on African passive margins: a record of margin bulges and far field very long wavelength deformations

    NASA Astrophysics Data System (ADS)

    Guillocheau, Francois; Robin, Cécile; Baby, Guillaume; Simon, Brendan; Rouby, Delphine; Loparev, Artiom

    2017-04-01

    The post-rift siliciclastic sediment budget of passive margins is a function of (1) the deformation (uplift) of the upstream catchment, of (2) the climate (precipitation) regime and of (3) the oceanic circulation (mainly since Miocene times). The main questions in source to sink studies are (1) to quantify the relative importance of the erosion due to uplifts or to precipitation changes and (2) to characterize the source of the sediments. A source to sink study was carried out in Western, Central and Austral Africa, characterized by anorogenic relief (plains and plateaus) that record long (several 100 km) to very long (several 1000 km) wavelength deformations respectively of lithospheric and mantle origin. The sink measurement was based on seismic lines and wells (industrial - IODP) using the VolumeEstimator software including the calculation of the uncertainties (Guillocheau et al., 2013, Basin Research). The source study was performed using dated stepped planation surfaces (etchplains and pediplains), mappable at catchments-scale (Guillocheau et al., in press, Gondwana Research). Results: (1) Deformation (uplift) is the dominant control of the sediment budget. Climate (precipitation) changes only enhance or inhibit a deformation-controlled flux. (2) The sources of siliciclastic sediments are either closed marginal bulges or far field domes due to mantle dynamics with river by-passing over long-lasting polygenic surfaces located between the bulges and domes. Two main periods of African-scale deformations (contemporaneous with an increase of the sedimentary flux) are confirmed, one during Late Cretaceous (Turonian-Coniacian) and the second around the Eocene-Oligocene boundary with a gap and intense chemical erosion from 75 Ma and mainly from 65 to 40 Ma.

  9. Snow cover and late fall movement influence wood frog survival during an unusually cold winter.

    PubMed

    O'Connor, Jason H; Rittenhouse, Tracy A G

    2016-07-01

    Understanding how organisms will respond to altered winter conditions is hampered by a paucity of information on the winter ecology for many species. Amphibians are sensitive to environmental temperature and moisture conditions and may be vulnerable to changes in winter climate. We used a combination of radio telemetry and field enclosures to monitor survival of the freeze-tolerant wood frog (Lithobates sylvaticus) during the unusually cold winter of 2013-2014. We experimentally manipulated snow cover to determine the effect of snow removal on winter survival. In addition, we placed a group of untracked frogs at locations used by tracked frogs prior to long-distance late fall movement to investigate whether late fall movement entailed survival consequences. Winter survival was highest (75.3 %) among frogs at post-movement locations that received natural snow cover. The odds of surviving the winter for frogs in the snow removal treatment was only 21.6 % that of frogs in the natural snow treatment. Likewise, paired frogs placed at pre-fall movement locations had only 35.1 % the odds of surviving as tracked frogs at post-fall movement locations. A comparison of a priori models that included microhabitat conditions measured at wood frog overwintering locations revealed that the minimum temperature experienced and the depth of the frog in the substrate explained additional variation in winter survival. Our results suggest that acute exposure to lethal temperature conditions is the most likely cause of mortality during this study, rather than energy exhaustion or desiccation. They also demonstrate the importance of snow cover to the winter survival of wood frogs.

  10. 4-aminopyridine-induced contracture in frog ventricle is due to calcium released from intracellular stores.

    PubMed

    Bhaskar, A; Subbanna, P K; Arasan, S; Rajapathy, J; Rao, J P; Subramani, S

    2008-01-01

    The aim of the study is to demonstrate the presence of intracellular calcium store in frog ventricle based on contractures induced by 4-aminopyridine in calcium-free media. Frog-ventricular strips were subjected to field stimulation at 0.2 Hz and the force of contraction was recorded after stabilization. The preparation was then kept quiescent for some time in solutions with different sodium concentrations, containing 0 or 1 mmol/L calcium. Caffeine, 4-aminopyridine (4-AP), or tetraethylammonium chloride was then added. Frog skeletal muscle preparations were used as positive controls for the caffeine experiments. Frog ventricular preparations did not develop contractures (sustained contractions) in the presence of caffeine (25 mmol/L), while frog skeletal muscle preparations developed caffeine-induced contractures. However, 4-AP (16 mmol/L) was able to induce contractures in quiescent frog ventricular preparations, even when they were superfused with calcium-free solution. 4-AP contractures in frog ventricle were seen in the presence of nifedipine also. Amplitude of 4-AP evoked contractures in frog ventricle were much larger in low sodium (30 mmol/L) and sodium-free (sodium substituted by lithium) solutions than in normal sodium solution, suggesting that the route of extrusion of the cytosolic calcium (released from intracellular stores by 4-AP) is the sodium calcium exchanger, which gets reversed in low sodium solutions. Tetraethylammonium chloride (TEA) was not able to induce contractures in frog ventricle suggesting that the contracture evoked by 4-AP is not due to its potassium channel blocking effect. In quiescent frog skeletal muscle preparations, caffeine as well as 4-AP induced contractures in calcium-free solutions. We therefore conclude that there is a caffeine-insensitive, 4-AP sensitive intracellular calcium store in the frog ventricle.

  11. Mw7.7 2013 Balochistan Earthquake. Slip-Distribution and Deformation Field in Oblique Tectonic Context

    NASA Astrophysics Data System (ADS)

    Klinger, Y.; Vallage, A.; Grandin, R.; Delorme, A.; Rosu, A. M.; Pierro-Deseilligny, M.

    2014-12-01

    The Mw7.7 2013 Balochistan earthquake ruptured 200 km of the Hoshab fault, the southern end of the Chaman fault. Azimuth of the fault changes by more than 30° along rupture, from a well-oriented strike-slip fault to a more thrust prone direction. We use the MicMac optical image software to correlate pairs of Landsat images taken before and after the earthquake to access to the horizontal displacement field associated with the earthquake. We combine the horizontal displacement with radar image correlation in range and radar interferometry to derive the co-seismic slip on the fault. The combination of these different datasets actually provides the 3D displacement field. We note that although the earthquake was mainly strike-slip all along the rupture length, some vertical motion patches exist, which locations seem to be controlled by kilometric-scale variations of the fault geometry. 5 pairs of SPOT images were also correlated to derive a 2.5m pixel-size horizontal displacement field, providing unique opportunity to look at deformation in the near field and to obtain high-resolution strike-slip and normal slip-distributions. We note a significant difference, especially in the normal component, between the slip localized at depth on the fault plane and the slip localized closer to the surface, with more apparent slip at the surface. A high-resolution map of ground rupture allows us to locate the distribution of the deformation over the whole rupture length. The rupture map also highlights multiple fault geometric complexities where we could quantify details of the slip distribution. At the rupture length-scale, the local azimuth variations between segments have a large impact on the expression of the localized slip at the surface. The combination of those datasets gives an overview of the large distribution of the deformation in the near field, corresponding to the co-seismic damage zone.

  12. Noninvasive, three-dimensional full-field body sensor for surface deformation monitoring of human body in vivo.

    PubMed

    Chen, Zhenning; Shao, Xinxing; He, Xiaoyuan; Wu, Jialin; Xu, Xiangyang; Zhang, Jinlin

    2017-09-01

    Noninvasive, three-dimensional (3-D), full-field surface deformation measurements of the human body are important for biomedical investigations. We proposed a 3-D noninvasive, full-field body sensor based on stereo digital image correlation (stereo-DIC) for surface deformation monitoring of the human body in vivo. First, by applying an improved water-transfer printing (WTP) technique to transfer optimized speckle patterns onto the skin, the body sensor was conveniently and harmlessly fabricated directly onto the human body. Then, stereo-DIC was used to achieve 3-D noncontact and noninvasive surface deformation measurements. The accuracy and efficiency of the proposed body sensor were verified and discussed by considering different complexions. Moreover, the fabrication of speckle patterns on human skin, which has always been considered a challenging problem, was shown to be feasible, effective, and harmless as a result of the improved WTP technique. An application of the proposed stereo-DIC-based body sensor was demonstrated by measuring the pulse wave velocity of human carotid artery. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  13. A cubic interpolation pipeline for fast computation of 3D deformation fields modeled using B-splines

    NASA Astrophysics Data System (ADS)

    Castro-Pareja, Carlos R.; Shekhar, Raj

    2006-02-01

    Fast computation of 3D deformation fields is critical to bringing the application of automated elastic image registration algorithms to routine clinical practice. However, it lies beyond the computational power of current microprocessors; therefore requiring implementations using either massively parallel computers or application-specific hardware accelerators. The use of massively parallel computers in a clinical setting is not practical or cost-effective, therefore making the use of hardware accelerators necessary. We present a hardware pipeline that allows accelerating the computation of 3D deformation fields to speeds up to two orders of magnitude faster than software implementations on current workstations and about 64 times faster than other previously reported architectures. The pipeline implements a version of the free-form deformation calculation algorithm, which is optimized to minimize the number of arithmetic operations required to calculate the transformation of a given set of neighboring voxels, thereby achieving an efficient and compact implementation in hardware which allows its use as part of a larger system.

  14. Source processes of near-field deformation accompanying recent lava lake level decrease at Nyiragongo, DR. Congo

    NASA Astrophysics Data System (ADS)

    Geirsson, Halldor; Smets, Benoît; d'Oreye, Nicolas; Cayol, Valerie; Samsonov, Sergey; De Rauw, Dominique; Kervyn, Francois

    2016-04-01

    Nyiragongo volcano in the Democratic Republic of Congo, Central Africa, is one of the rare volcanoes that host a long-living lava lake. The evolution of this lava lake is very dynamic, with height changes spanning hundreds of meters over the past decades and including drastic height changes in relation to flank eruptions of the volcano in 1977 and 2002 (Smets et al., this meeting). Since September 30, 2011, the level of the lava lake has been progressively falling, reaching ~70 m below the lowest platform (termed "platform P3" hereafter) in July 2014. Platform P3 is constructed from successive overflows of the lava lake from 2002 to 2011, amounting to ~400 m thickness since the emptying of the lava lake following the 2002 flank eruption. Coinciding with the recent fall of the lava lake, differences of photogrammetry-derived DEM models, and InSAR time series, show a very near-field (out to ~200-300 m distance from the ~200 m-wide lava lake, i.e. on platform P3) deformation signal with up to meter-scale deformation near the crater. Ring-fractures have also formed in platform P3. Here we compare and contrast plausible models of processes contributing to this near-field deformation, including thermal contraction, elastic response, block rotation, structural weaknesses, and subsurface shape of the lava lake.

  15. Full-field Deformation Measurement Techniques for a Rotating Composite Shaft

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.; Ruggeri, Charles R.; Martin, Richard E.; Roberts, Gary D.; Handschuh, Robert F.; Roth, Don J.

    2012-01-01

    Test methods were developed to view global and local deformation in a composite tube during a test in which the tube is rotating at speeds and torques relevant to rotorcraft shafts. Digital image correlation (DIC) was used to provide quantitative displacement measurements during the tests. High speed cameras were used for the DIC measurements in order to capture images at sufficient frame rates and with sufficient resolution while the tube was rotating at speeds up to 5,000 rpm. Surface displacement data was resolved into cylindrical coordinates in order to measure rigid body rotation and global deformation of the tube. Tests were performed on both undamaged and impact damaged tubes in order to evaluate the capability to detect local deformation near an impact damaged site. Measurement of radial displacement clearly indicated a local buckling deformation near the impacted site in both dynamic and static tests. X-ray computed tomography (CT) was used to investigate variations in fiber architecture within the composite tube and to detect impact damage. No growth in the impact damage area was observed by DIC during dynamic testing or by x-ray CT in post test inspection of the composite tube.

  16. Full-field Deformation Measurement Techniques for a Rotating Composite Shaft

    NASA Technical Reports Server (NTRS)

    Kohlman, Lee W.; Ruggeri, Charles R.; Martin, Richard E.; Roberts, Gary D.; Handschuh, Robert F.; Roth, Don J.

    2012-01-01

    Test methods were developed to view global and local deformation in a composite tube during a test in which the tube is rotating at speeds and torques relevant to rotorcraft shafts. Digital image correlation (DIC) was used to provide quantitative displacement measurements during the tests. High speed cameras were used for the DIC measurements in order to capture images at sufficient frame rates and with sufficient resolution while the tube was rotating at speeds up to 5,000 rpm. Surface displacement data was resolved into cylindrical coordinates in order to measure rigid body rotation and global deformation of the tube. Tests were performed on both undamaged and impact damaged tubes in order to evaluate the capability to detect local deformation near an impact damaged site. Measurement of radial displacement clearly indicated a local buckling deformation near the impacted site in both dynamic and static tests. X-ray computed tomography (CT) was used to investigate variations in fiber architecture within the composite tube and to detect impact damage. No growth in the impact damage area was observed by DIC during dynamic testing or by x-ray CT in post test inspection of the composite tube.

  17. Effects of polychlorinated biphenyl 126 on green frog (Rana clamitans) and leopard frog (Rana pipiens) hatching success, development, and metamorphosis

    SciTech Connect

    Rosenshield, M.L.; Jofre, M.B.; Karasov, W.H.

    1999-11-01

    Although increasing evidence links plana chlorinated hydrocarbons, such as polychlorinated biphenyls (PCBs), to decreases in survival and reproduction of fish, mammals, and birds near Green Bay, Wisconsin, and the Great Lakes, USA, relatively little is known of their bioaccumulation or of their possible effects in amphibians. The authors exposed embryos and larvae of two ranid species commonly occurring in the Green Bay ecosystem, the green frog (Rana clamitans) and the leopard frog (Rana pipiens), to PCB 126, a model coplanar PCB compound. Nominal concentrations ranged from 0.005 to 50 {micro}g/L, and exposure lasted through metamorphosis. Tissue concentrations of PCB 126 in tadpoles that did not metamorphose by the end of the experiment ranged from 1.2 to 9,600 ng/g wet mass. No significant mortality of embryos occurred before hatching; however, survival of larvae was significantly reduced at the highest concentration for both species. Few deformities were observed, but the incidence of edema was significantly higher in tadpoles exposed to 50 {micro}g/L. Swimming speed and growth of tadpoles was also significantly reduced in this treatment. The percent of tadpoles that reached metamorphosis was significantly lower in green frogs at the highest concentration, and no leopard frogs survived past day 47 of the experiment in this treatment. At high concentrations, PCB 126 affected both ranid species; however, sublethal effects were not apparent for the parameters the authors measured at concentrations that occur in water in the Green Bay ecosystem.

  18. Far-field correlation of bidirectional tracking beams due to wave-front deformation in inter-satellites optical communication links.

    PubMed

    Yu, Siyuan; Ma, Zhongtian; Ma, Jing; Wu, Feng; Tan, Liying

    2015-03-23

    In some applications of optical communication systems, such as inter-satellites optical communication, the correlation of the bidirectional tracking beams changes in far-field as a result of wave-front deformation. Far-field correlation model with wave-front deformation on tracking stability is established. Far-field correlation function and factor have been obtained. Combining with parameters of typical laser communication systems, the model is corrected. It shows that deformation pointing-tracking errors θ(A) and θ(B), far-field correlation factor δ depend on RMS of deformation error rms, which decline with a increasing rms including Tilt and Coma. The principle of adjusting far-field correlation factor with wave-front deformation to compensate deformation pointing-tracking errors has been given, through which the deformation pointing-tracking error is reduced to 18.12″ (Azimuth) and 17.65″ (Elevation). Work above possesses significant reference value on optimization design in inter-satellites optical communication.

  19. An experimental study on the motion, deformation and electrical charging of water drops falling in oil in the presence of high voltage D.C. electric field

    SciTech Connect

    Jalaal, M.; Khorshidi, B.; Esmaeilzadeh, E.

    2010-11-15

    The motion, deformation and electrical charging of conducting water drops falling in an insulating liquid subjected to various electric fields strength were studied experimentally. The drop motion was recorded contentiously by high speed camera and their responses to deformation under the influence of electric field were digitally extracted by image processing of the sequential frames. Two parameters were defined for describing the deviation and deformation of the drops under the electric forces. Outcomes depicted that the deviation of the drops from the vertical line would be increased by adding to the applied electrical potential as well as reduction of drop size. Moreover, regarding to deformation diagram, the results revealed a dissimilar deformation manner between large and small drops, which can be helpful in describing the drop-drop electro coalescence phenomena and in design of electrically driven droplet-based systems. (author)

  20. Yielding and Irreversible Deformation below the Microscale: Surface Effects and Non-Mean-Field Plastic Avalanches

    PubMed Central

    Moretti, Paolo; Cerruti, Benedetta; Miguel, M.-Carmen

    2011-01-01

    Nanoindentation techniques recently developed to measure the mechanical response of crystals under external loading conditions reveal new phenomena upon decreasing sample size below the microscale. At small length scales, material resistance to irreversible deformation depends on sample morphology. Here we study the mechanisms of yield and plastic flow in inherently small crystals under uniaxial compression. Discrete structural rearrangements emerge as a series of abrupt discontinuities in stress-strain curves. We obtain the theoretical dependence of the yield stress on system size and geometry and elucidate the statistical properties of plastic deformation at such scales. Our results show that the absence of dislocation storage leads to crucial effects on the statistics of plastic events, ultimately affecting the universal scaling behavior observed at larger scales. PMID:21666747

  1. Kh. A. Rakhmatulin's scientific legacy in the field of mechanics of deformable rigid bodies

    NASA Astrophysics Data System (ADS)

    Goldstein, R. V.; Dem'yanov, Yu. A.; Nikitin, L. V.; Smirnov, N. N.; Shemyakin, E. I.

    2010-02-01

    Kh. A. Rakhmatulin's scientific activity was aimed at solving the most important scientific and technical problems encountered by the country. Khalil Akhmetovich was a unique combination of a theorist and an experimenter, an engineer and an inventor, a talented teacher and a scientific research manager. He fruitfully worked in mechanics of deformable solids (the corresponding results are surveyed in the present paper) as well as in fluid mechanics (as described in detail in the journal [1] dedicated to his memory).

  2. The Homing Frog: High Homing Performance in a Territorial Dendrobatid Frog Allobates femoralis (Dendrobatidae)

    PubMed Central

    Pašukonis, Andrius; Ringler, Max; Brandl, Hanja B; Mangione, Rosanna; Ringler, Eva; Hödl, Walter; Tregenza, T

    2013-01-01

    Dendrobatidae (dart-poison frogs) exhibit some of the most complex spatial behaviors among amphibians, such as territoriality and tadpole transport from terrestrial clutches to widely distributed deposition sites. In species that exhibit long-term territoriality, high homing performance after tadpole transport can be assumed, but experimental evidence is lacking, and the underlying orientation mechanisms are unknown. We conducted a field translocation experiment to test whether male Allobates femoralis, a dendrobatid frog with paternal extra-territorial tadpole transport, are capable of homing after experimental removal, as well as to quantify homing success and speed. Translocated individuals showed a very high homing success for distances up to 200 m and successfully returned from up to 400 m. We discuss the potential orientation mechanisms involved and selective forces that could have shaped this strong homing ability. PMID:25104869

  3. The Homing Frog: High Homing Performance in a Territorial Dendrobatid Frog Allobates femoralis (Dendrobatidae).

    PubMed

    Pašukonis, Andrius; Ringler, Max; Brandl, Hanja B; Mangione, Rosanna; Ringler, Eva; Hödl, Walter

    2013-09-01

    Dendrobatidae (dart-poison frogs) exhibit some of the most complex spatial behaviors among amphibians, such as territoriality and tadpole transport from terrestrial clutches to widely distributed deposition sites. In species that exhibit long-term territoriality, high homing performance after tadpole transport can be assumed, but experimental evidence is lacking, and the underlying orientation mechanisms are unknown. We conducted a field translocation experiment to test whether male Allobates femoralis, a dendrobatid frog with paternal extra-territorial tadpole transport, are capable of homing after experimental removal, as well as to quantify homing success and speed. Translocated individuals showed a very high homing success for distances up to 200 m and successfully returned from up to 400 m. We discuss the potential orientation mechanisms involved and selective forces that could have shaped this strong homing ability.

  4. A set of alternative explanations to account for the deformation field at Montserrat, West Indies

    NASA Astrophysics Data System (ADS)

    Collinson, Amy; Neuberg, Jurgen; Pascal, Karen

    2015-04-01

    For almost 20 years, Soufrière Hills Volcano, Monsterrat, has been in a state of volcanic unrest. Intermittent periods of dome building have been punctuated by explosive eruptions and dome collapse events, endangering the lives of the inhabitants of the island. To date, there have been numerous phases to the activity, with the current activity designated Pause 5. There has not been any active magma extrusion since February 2010, and the last significant explosive (ash-venting) event occurred in March 2012. However, the volcano continues to emit an average of 374t/d SO2 and shows signs of deformation. Current observations indicate a line lengthening between several pairs of GPS stations across the island, suggesting an overall inflation of Montserrat. Through the use of three-dimensional numerical modelling using a finite element method, we explore the potential sources of this deformation, ranging from an inflating magma chamber or dyke - suggesting ongoing volcanic activity, to the existence of an active left-lateral strike-slip fault - which may indicate cessation of volcanic activity. We show the effect of different dyke sources (shapes, characters and depths) on the surface displacement. Furthermore, through the inclusion of topographic data, we investigate how the topography may affect the displacement pattern at the surface. Alternatively, we determine how much fault slip would be required in order to derive the deformation observed.

  5. Simulation study of the in-situ formation deformation behavior of a shallow formation in the Southern Kanto Natural gas field, Chiba Prefecture, Japan

    NASA Astrophysics Data System (ADS)

    Adachi, M.; Matsuyama, R.; Nakagawa, T.; Kuroshima, S.; Ogatsu, T.; Adachi, R.

    2015-11-01

    In 2010, eight companies which are exploiting natural gas and brine water in the Southern Kanto natural gas field, Chiba prefecture, Japan constructed an in-situ formation deformation monitoring well with a depth of approximately 80 m, and in-situ formation deformation was measured on a trial basis. After this field test, by conducting the simulation study, we verified whether the deformation behavior at the monitoring well was perfectly elastic or not. In addition, we compared in-situ rock properties like Young's modulus and Poisson's ratio which were estimated by the simulation study with those determined from a triaxial compression test.

  6. A Comparison of V-Frog[C] to Physical Frog Dissection

    ERIC Educational Resources Information Center

    Lalley, James P.; Piotrowski, Phillip S.; Battaglia, Barbara; Brophy, Keith; Chugh, Kevin

    2010-01-01

    The purpose of the present study was to examine and compare the effectiveness of virtual frog dissection using V-Frog[C] and physical frog dissection on learning, retention, and affect. Subjects were secondary students enrolled in year-long life science classes in a suburban high school (N=102). Virtual dissections were done with V-Frog[C], a…

  7. To Be or Not to Be...a Frog: The Frog Prince and Shifting Paradigms.

    ERIC Educational Resources Information Center

    Crane, Lisa Marie

    1997-01-01

    Discusses three modern variations of the classic "Frog Prince" folk tale: "Pondlarker" (Fred Gwynne); "The Frog Prince Continued" (Jon Scieszka); and "The Prince of the Pond" (Donna Jo Napoli). Notes that these variants create a world in which frogs can have values, wisdom, and emotion, and in which frogs can influence the ways of humanity. (RS)

  8. To Be or Not to Be...a Frog: The Frog Prince and Shifting Paradigms.

    ERIC Educational Resources Information Center

    Crane, Lisa Marie

    1997-01-01

    Discusses three modern variations of the classic "Frog Prince" folk tale: "Pondlarker" (Fred Gwynne); "The Frog Prince Continued" (Jon Scieszka); and "The Prince of the Pond" (Donna Jo Napoli). Notes that these variants create a world in which frogs can have values, wisdom, and emotion, and in which frogs can influence the ways of humanity. (RS)

  9. Surface Deformation and Direct Field Observation to Constrain Conceptual Models of Hydraulic Fracture Growth and Form

    NASA Astrophysics Data System (ADS)

    Slack, W.; Murdoch, L.

    2016-12-01

    Hydraulic fractures can be created in shallow soil or bedrock to promote processes that destroy or remove chemical contaminants. The form of the fracture plays an important role in how it is used in such applications. We created more than 4500 environmental hydraulic fractures at approximately 300 sites since 1990, and we measured surface deformation at many. Several of these sites subsequently were excavated to evaluate fracture form in detail. In one recent example, six hydraulic fractures were created at 1.5m depth while we measured upward displacement and tilt at 15 overlying locations. We excavated in the vicinities of two of the fractures and mapped the exposed fractures. Tilt vectors were initially symmetric about the borehole but radiated from a point that moved southwest with time. Upward displacement of as much as 2.5 cm covered a region 5m to 6m across. The maximum displacement was roughly at the center of the deformed region but was 2m southwest of the borehole, consistent with the tilt data. Excavation revealed an oblong, proppant-filled fracture over 4.2 m in length with a maximum thickness of 1 cm, so the proppant covers a region that is smaller than the uplifted area and the proppant thickness is roughly half of the uplift. The fracture was shaped like a shallow saucer with maximum dips of approximately 15o at the southwestern end. The pattern of tilt and uplift generally reflect the aperture of the underlying pressurized fracture, but the deformation extends beyond the extent of the sand proppant so a quantitative interpretation requires inversion. Inversion of the tilt data using a simple double dislocation model under-estimates the extent but correctly predicts the depth, orientation, and off-centered location. Inversion of uplift using a model that assumes the overburden deforms like a plate over-estimates the extent. Neither can characterize the curved shape. A forward model using FEM analysis capable of representing 3D shapes is capable of

  10. New Integrable 4D Quantum Field Theories from Strongly Deformed Planar N=4 Supersymmetric Yang-Mills Theory.

    PubMed

    Gürdoğan, Ömer; Kazakov, Vladimir

    2016-11-11

    We introduce a family of new integrable quantum field theories in four dimensions by considering the γ-deformed N=4 supersymmetric Yang-Mills (SYM) theory in the double scaling limit of large imaginary twists and small coupling. This limit discards the gauge fields and retains only certain Yukawa and scalar interactions with three arbitrary effective couplings. In the 't Hooft limit, these 4D theories are integrable, and contain a wealth of conformal correlators such that the whole arsenal of AdS/CFT integrability remains applicable. As a special case of these models, we obtain a quantum field theory of two complex scalars with a chiral, quartic interaction. The Berenstein-Maldacena-Nastase vacuum anomalous dimension is dominated in each loop order by a single "wheel" graph, whose bulk represents an integrable "fishnet" graph. This explicitly demonstrates the all-loop integrability of gamma-deformed planar N=4 SYM theory, at least in our limit. Using this feature and integrability results we provide an explicit conjecture for the periods of double-wheel graphs with an arbitrary number of spokes in terms of multiple zeta values of limited depth.

  11. New Integrable 4D Quantum Field Theories from Strongly Deformed Planar N =4 Supersymmetric Yang-Mills Theory

    NASA Astrophysics Data System (ADS)

    Gürdoǧan, Ömer; Kazakov, Vladimir

    2016-11-01

    We introduce a family of new integrable quantum field theories in four dimensions by considering the γ -deformed N =4 supersymmetric Yang-Mills (SYM) theory in the double scaling limit of large imaginary twists and small coupling. This limit discards the gauge fields and retains only certain Yukawa and scalar interactions with three arbitrary effective couplings. In the `t Hooft limit, these 4D theories are integrable, and contain a wealth of conformal correlators such that the whole arsenal of AdS /CFT integrability remains applicable. As a special case of these models, we obtain a quantum field theory of two complex scalars with a chiral, quartic interaction. The Berenstein-Maldacena-Nastase vacuum anomalous dimension is dominated in each loop order by a single "wheel" graph, whose bulk represents an integrable "fishnet" graph. This explicitly demonstrates the all-loop integrability of gamma-deformed planar N =4 SYM theory, at least in our limit. Using this feature and integrability results we provide an explicit conjecture for the periods of double-wheel graphs with an arbitrary number of spokes in terms of multiple zeta values of limited depth.

  12. Uniform electric-field-induced non-Newtonian rheology of a dilute suspension of deformable Newtonian drops

    NASA Astrophysics Data System (ADS)

    Mandal, Shubhadeep; Chakraborty, Suman

    2017-09-01

    The rheological behavior of a dilute emulsion comprised of neutrally buoyant drops suspended in an immiscible medium under the combined influence of a uniform electric field and simple shear flow is analyzed. Considering the drops and suspending medium as Newtonian and leaky dielectrics, the effective emulsion stress tensor is obtained when the fluid motion is governed by the Stokes equations. The present study takes into account an arbitrarily oriented uniform electric field in the plane of shear flow. A small-deformation analysis is performed to study this coupled electrohydrodynamic problem considering weak imposed shear flow and weak surface charge convection. Analytical expressions are obtained for the effective shear viscosity and normal stress differences of the dilute emulsion. The tilt angle (orientation angle of the applied electric field relative to the direction of shear flow) is found to affect the emulsion rheology. Key results show that the dilute emulsion exhibits non-Newtonian behavior such as shear-rate-dependent effective viscosity and nonzero first and second normal stress differences. In the absence of shape deformation and charge convection, a dilute emulsion displays shear thinning or shear thickening behavior depending on the drop polarization and tilt angle. The effective viscosity of the dilute emulsion can be lower or higher than the viscosity of the suspending medium depending on the electrical property ratios, tilt angle, and relative strength of the electric stress as compared with viscous stress. Surface charge convection significantly affects the electrohydrodynamic flow and thereby modifies the effective viscosity and normal stress differences. The applied electric field significantly affects the drop shape and orientation angle and thereby modifies the effective viscosity and normal stress differences. Both the surface charge convection and shape deformation can increase or decrease the effective viscosity and normal stress

  13. The Classroom Animal: The Leopard Frog.

    ERIC Educational Resources Information Center

    Science and Children, 1985

    1985-01-01

    Describes the natural history of the leopard frog and factors which make it appropriate for short-term study in the classroom. Information on the frog's habits, life cycle, housing, care, and health is included. (DH)

  14. Effective of the q-deformed pseudoscalar magnetic field on the charge carriers in graphene

    SciTech Connect

    Eshghi, M. E-mail: m.eshghi@semnan.ac.ir; Mehraban, H.

    2016-08-15

    In this paper, we have obtained exact analytical solutions of the time-independent Dirac-Weyl equation for the charge carriers with q-deformed pseudoscalar magnetic barrier (PMB) in graphene by using the ansatz method. We have also found a solution that describes the left propagating wave function to calculation of the reflection and transmission coefficients using the Riemann’s equation. This allows us to conclude about the Dirac-Weyl equation with PMB and to understand quantum behavior of the Dirac fermions. Finally, some of the numerical results are shown, too.

  15. Continuum modeling of the electric-field-induced tension in deforming lipid vesicles

    NASA Astrophysics Data System (ADS)

    McConnell, Lane C.; Miksis, Michael J.; Vlahovska, Petia M.

    2015-12-01

    We computationally investigate the deformation of a closed bilayer membrane (vesicle) in a DC electric pulse with a goal of understanding cell electroporation. The electric stresses exerted on the area-incompressible interface generate non-uniform tension that can exceed the membrane lysis tension and drive pore opening. Using the two-dimensional boundary integral method, we track the spatial and temporal evolution of the highest membrane tension. Our simulations highlight the dynamic nature of electrotension and, in contrast to the common assumption, a possibility of electroporation away from the poles.

  16. Continuum modeling of the electric-field-induced tension in deforming lipid vesicles.

    PubMed

    McConnell, Lane C; Miksis, Michael J; Vlahovska, Petia M

    2015-12-28

    We computationally investigate the deformation of a closed bilayer membrane (vesicle) in a DC electric pulse with a goal of understanding cell electroporation. The electric stresses exerted on the area-incompressible interface generate non-uniform tension that can exceed the membrane lysis tension and drive pore opening. Using the two-dimensional boundary integral method, we track the spatial and temporal evolution of the highest membrane tension. Our simulations highlight the dynamic nature of electrotension and, in contrast to the common assumption, a possibility of electroporation away from the poles.

  17. Acoustic Monitoring System for Frog Population Estimation Using In-Situ Progressive Learning

    NASA Astrophysics Data System (ADS)

    Aboudan, Adam

    Frog populations are considered excellent bio-indicators and hence the ability to monitor changes in their populations can be very useful for ecological research and environmental monitoring. This thesis presents a new population estimation approach based on the recognition of individual frogs of the same species, namely the Pseudacris Regilla (Pacific Chorus Frog), which does not rely on the availability of prior training data. An in-situ progressive learning algorithm is developed to determine whether an incoming call belongs to a previously detected individual frog or a newly encountered individual frog. A temporal call overlap detector is also presented as a pre-processing tool to eliminate overlapping calls. This is done to prevent the degrading of the learning process. The approach uses Mel-frequency cepstral coefficients (MFCCs) and multivariate Gaussian models to achieve individual frog recognition. In the first part of this thesis, the MFCC as well as the related linear predictive cepstral coefficients (LPCC) acoustic feature extraction processes are reviewed. The Gaussian mixture models (GMM) are also reviewed as an extension to the classical Gaussian modeling used in the proposed approach. In the second part of this thesis, the proposed frog population estimation system is presented and discussed in detail. The proposed system involves several different components including call segmentation, feature extraction, overlap detection, and the in-situ progressive learning process. In the third part of the thesis, data description and system performance results are provided. The process of synthetically generating test sequences of real frog calls, which are applied to the proposed system for performance analysis, is described. Also, the results of the system performance are presented which show that the system is successful in distinguishing individual frogs, hence capable of providing reasonable estimates of the frog population. The system can readily be

  18. What's the Difference between Frogs and Toads?

    ERIC Educational Resources Information Center

    Brown, Herrick

    2004-01-01

    The difference between frogs and toads can be determined scientifically but is based in the historic use of the terms frog and toad. These are Old English words for the common frog, "Rana temporaria," and the common toad, "Bufo bufo," both inhabitants of the British Isles. In the process of describing a new anuran species,…

  19. 49 CFR 213.137 - Frogs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Frogs. 213.137 Section 213.137 Transportation... TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.137 Frogs. (a) The flangeway depth measured from a plane across the wheel-bearing area of a frog on Class 1 track shall not be less than 13/8 inches, or...

  20. 49 CFR 213.137 - Frogs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Frogs. 213.137 Section 213.137 Transportation... TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.137 Frogs. (a) The flangeway depth measured from a plane across the wheel-bearing area of a frog on Class 1 track shall not be less than 13/8 inches, or...

  1. 49 CFR 213.137 - Frogs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Frogs. 213.137 Section 213.137 Transportation... TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.137 Frogs. (a) The flangeway depth measured from a plane across the wheel-bearing area of a frog on Class 1 track shall not be less than 13/8 inches, or...

  2. 49 CFR 213.137 - Frogs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Frogs. 213.137 Section 213.137 Transportation... TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.137 Frogs. (a) The flangeway depth measured from a plane across the wheel-bearing area of a frog on Class 1 track shall not be less than 13/8 inches, or...

  3. What's the Difference between Frogs and Toads?

    ERIC Educational Resources Information Center

    Brown, Herrick

    2004-01-01

    The difference between frogs and toads can be determined scientifically but is based in the historic use of the terms frog and toad. These are Old English words for the common frog, "Rana temporaria," and the common toad, "Bufo bufo," both inhabitants of the British Isles. In the process of describing a new anuran species,…

  4. 49 CFR 213.137 - Frogs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Frogs. 213.137 Section 213.137 Transportation... TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.137 Frogs. (a) The flangeway depth measured from a plane across the wheel-bearing area of a frog on Class 1 track shall not be less than 13/8 inches, or...

  5. 3D Finite Element Modeling of the 2009 L'Aquila Earthquake Deformation Field

    NASA Astrophysics Data System (ADS)

    Volpe, M.; Casarotti, E.; Piersanti, A.

    2009-12-01

    The L'Aquila earthquake (Mw 6.3) occurred on April 6th at 01:32 UTC in the Central Appennines at a depth of about 9 km and was felt all over Central Italy. The main shock was preceded by a long seismic sequence started several months before and was followed by thousands of aftershocks, some of them with Mw>4. We built up a high resolution three-dimensional model, incorporating surface topography, which was discretized using 20-nodes brick elements. The element horizontal size is biased from 500 m to 2 km using the paving meshing algorithm in combination with an appropriate adaptive sizing function. A realistic rheology was introduced from a vp/vpvs travel time tomographic model. We computed the co-seismic deformation induced by the earthquake by means of a recently developed finite elements simulation tool, FEMSA (Finite Element Modeling for Seismic Applications). We used different seismic source models obtained from fault inversion of GPS measurements, joint inversion of strong motion and GPS data and from inversion of DInSAR displacements. The synthetic deformation patterns were compared with the experimental results in order to evaluate which source model better reconciles the data and quantify the trade off introduced by 1D simulations.

  6. Polymorphism of iron at high pressure: A 3D phase-field model for displacive transitions with finite elastoplastic deformations

    NASA Astrophysics Data System (ADS)

    Vattré, A.; Denoual, C.

    2016-07-01

    A thermodynamically consistent framework for combining nonlinear elastoplasticity and multivariant phase-field theory is formulated at large strains. In accordance with the Clausius-Duhem inequality, the Helmholtz free energy and time-dependent constitutive relations give rise to displacive driving forces for pressure-induced martensitic phase transitions in materials. Inelastic forces are obtained by using a representation of the energy landscape that involves the concept of reaction pathways with respect to the point group symmetry operations of crystal lattices. On the other hand, additional elastic forces are derived for the most general case of large strains and rotations, as well as nonlinear, anisotropic, and different elastic pressure-dependent properties of phases. The phase-field formalism coupled with finite elastoplastic deformations is implemented into a three-dimensional Lagrangian finite element approach and is applied to analyze the iron body-centered cubic (α-Fe) into hexagonal close-packed (ɛ-Fe) phase transitions under high hydrostatic compression. The simulations exhibit the major role played by the plastic deformation in the morphological and microstructure evolution processes. Due to the strong long-range elastic interactions between variants without plasticity, a forward α → ɛ transition is energetically unfavorable and remains incomplete. However, plastic dissipation releases considerably the stored strain energy, leading to the α ↔ ɛ ↔α‧ (forward and reverse) polymorphic phase transformations with an unexpected selection of variants.

  7. An asymptotic finite plane deformation analysis of the elastostatic fields at a notch vertex of an incompressible hyperelastic material

    NASA Astrophysics Data System (ADS)

    Arfaoui, Makrem; Mansouri, Khalil; Rezgui, Ali

    2008-09-01

    This Note is devoted to the theoretical study of the elastostatic fields at a vertex notch under general far-field loading conditions. The analysis is based on the finite plane deformation hyperelasticity theory for an incompressible Mooney-Rivlin material. We approach the solution, near the singularity, by a mixed asymptotic development. We show that the shape of the solution depends on the opening angle of the notch and that there is singularity if the notch is concave. Furthermore, we show that a pure loading mode II gives rise to the opening of the notch vertex in contrast to the linear elasticity. To cite this article: M. Arfaoui et al., C. R. Mecanique 336 (2008).

  8. Pair-Wise, Deformable Mirror, Image Plane-Based Diversity Electric Field Estimation for High Contrast Coronagraphy

    NASA Technical Reports Server (NTRS)

    Give'on, Amir; Kern, Brian D.; Shaklan, Stuart

    2011-01-01

    In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.

  9. Pair-Wise, Deformable Mirror, Image Plane-Based Diversity Electric Field Estimation for High Contrast Coronagraphy

    NASA Technical Reports Server (NTRS)

    Give'on, Amir; Kern, Brian D.; Shaklan, Stuart

    2011-01-01

    In this paper we describe the complex electric field reconstruction from image plane intensity measurements for high contrast coronagraphic imaging. A deformable mirror (DM) surface is modied with pairs of complementary shapes to create diversity in the image plane of the science camera where the intensity of the light is measured. Along with the Electric Field Conjugation correction algorithm, this estimation method has been used in various high contrast imaging testbeds to achieve the best contrasts to date both in narrow and in broad band light. We present the basic methodology of estimation in easy to follow list of steps, present results from HCIT and raise several open quations we are confronted with using this method.

  10. The Sex Chromosomes of Frogs: Variability and Tolerance Offer Clues to Genome Evolution and Function

    PubMed Central

    Malcom, Jacob W.; Kudra, Randal S.; Malone, John H.

    2014-01-01

    Frog sex chromosomes offer an ideal system for advancing our understanding of genome evolution and function because of the variety of sex determination systems in the group, the diversity of sex chromosome maturation states, the ease of experimental manipulation during early development. After briefly reviewing sex chromosome biology generally, we focus on what is known about frog sex determination, sex chromosome evolution, and recent, genomics-facilitated advances in the field. In closing we highlight gaps in our current knowledge of frog sex chromosomes, and suggest priorities for future research that can advance broad knowledge of gene dose and sex chromosome evolution. PMID:25031658

  11. Seeing the unseen: Complete volcano deformation fields by recursive filtering of satellite radar interferograms

    NASA Astrophysics Data System (ADS)

    Gonzalez, Pablo J.

    2017-04-01

    Automatic interferometric processing of satellite radar data has emerged as a solution to the increasing amount of acquired SAR data. Automatic SAR and InSAR processing ranges from focusing raw echoes to the computation of displacement time series using large stacks of co-registered radar images. However, this type of interferometric processing approach demands the pre-described or adaptive selection of multiple processing parameters. One of the interferometric processing steps that much strongly influences the final results (displacement maps) is the interferometric phase filtering. There are a large number of phase filtering methods, however the "so-called" Goldstein filtering method is the most popular [Goldstein and Werner, 1998; Baran et al., 2003]. The Goldstein filter needs basically two parameters, the size of the window filter and a parameter to indicate the filter smoothing intensity. The modified Goldstein method removes the need to select the smoothing parameter based on the local interferometric coherence level, but still requires to specify the dimension of the filtering window. An optimal filtered phase quality usually requires careful selection of those parameters. Therefore, there is an strong need to develop automatic filtering methods to adapt for automatic processing, while maximizing filtered phase quality. Here, in this paper, I present a recursive adaptive phase filtering algorithm for accurate estimation of differential interferometric ground deformation and local coherence measurements. The proposed filter is based upon the modified Goldstein filter [Baran et al., 2003]. This filtering method improves the quality of the interferograms by performing a recursive iteration using variable (cascade) kernel sizes, and improving the coherence estimation by locally defringing the interferometric phase. The method has been tested using simulations and real cases relevant to the characteristics of the Sentinel-1 mission. Here, I present real examples

  12. Near-field deformation from the El Mayor-Cucapah earthquake revealed by differential LIDAR.

    PubMed

    Oskin, Michael E; Arrowsmith, J Ramon; Hinojosa Corona, Alejandro; Elliott, Austin J; Fletcher, John M; Fielding, Eric J; Gold, Peter O; Gonzalez Garcia, J Javier; Hudnut, Ken W; Liu-Zeng, Jing; Teran, Orlando J

    2012-02-10

    Large [moment magnitude (M(w)) ≥ 7] continental earthquakes often generate complex, multifault ruptures linked by enigmatic zones of distributed deformation. Here, we report the collection and results of a high-resolution (≥nine returns per square meter) airborne light detection and ranging (LIDAR) topographic survey of the 2010 M(w) 7.2 El Mayor-Cucapah earthquake that produced a 120-kilometer-long multifault rupture through northernmost Baja California, Mexico. This differential LIDAR survey completely captures an earthquake surface rupture in a sparsely vegetated region with pre-earthquake lower-resolution (5-meter-pixel) LIDAR data. The postevent survey reveals numerous surface ruptures, including previously undocumented blind faults within thick sediments of the Colorado River delta. Differential elevation changes show distributed, kilometer-scale bending strains as large as ~10(3) microstrains in response to slip along discontinuous faults cutting crystalline bedrock of the Sierra Cucapah.

  13. Hydraulic-fracture growth in dipping anisotropic strata as viewed through the surface deformation field

    SciTech Connect

    Holzhausen, G.R.; Haase, C.S.; Stow, S.H.; Gazonas, G.

    1985-01-01

    In 1983 and 1984 Oak Rdige National Laboratory conducted a series of precision ground deformation measurements before, during, and after the generation of several large hydraulic fractures in a dipping member of the Cambrian Conasauga Shale. Each fracture was produced by the injection of approximately 500,000 L of slurry on a single day. Injection depth was 300 m. Leveling surveys were run several days before and several days after the injections. An array of eight high-precision borehole tiltmeters monitored ground deformations continuously for a period of several weeks. Analysis of the leveling and the tilt measurements revealed surface uplifts as great as 25 mm and tilts of tens of microradians during each injection. Furthermore, partial recovery (subsidence) of the ground took place during the days following an injection, accompanied by shifts in the position of maximum resultant uplift. Interpretation of the tilt measurements is consistent with stable widening and extension of hydraulic fractures with subhorizontal orientations. Comparison of the measured tilt patterns with fracture orientations established from logging of observation wells suggests that shearing parallel to the fracture planes accompanied fracture dilation. This interpretation is supported by measured tilts and ground uplifts that were as much as 100 percent greater than those expected from fracture dilation alone. Models of elastically anisotropic overburden rock do not explain the measured tilt patterns in the absence of shear stresses in the fracture planes. This work represents the first large-scale hydraulic-fracturing experiment in which the possible effects of material anisotropy and fracture-parallel shears have been measured and interpreted.

  14. Surface Deformation Associated with Geothermal Fluids Extraction at the Cerro Prieto Geothermal Field, Baja California, Mexico Revealed by DInSAR Technique

    NASA Astrophysics Data System (ADS)

    Sarychikhina, O.; Glowacka, E.; Mojarro, J.

    2016-08-01

    The Differential Synthetic Aperture Radar Interferometry (DInSAR) is widely used for surface deformation detection and monitoring.In this paper, ERS-1/2, ENVISAT and RADARSAT-2 synthetic aperture radar (SAR) images acquired between 1993 and 2014 were processed to investigate the evolution of surface deformation at the Cerro Prieto geothermal field, Baja California, Mexico. The conventional DInSAR together with the interferogram stacking method was applied. Average LOS (line of sight) displacement velocity maps were generated for different periods: 1993 - 1997, 1998 - 2000, 2004, 2005, 2007, 2009, and 2012 - 2014, revealing that the area corresponding to Cerro Prieto basin presented the important surface deformation (mainly subsidence) during the entire time of investigation. The changes in the surface deformation pattern and rate were identified. These changes have a good correlation in time with the changes of production in the Cerro Prieto geothermal field.

  15. Coseismic Faults and Crust Deformation Accompanied the 2008 Wenchuan Earthquake, China by Field Investigation and InSAR Interferogram

    NASA Astrophysics Data System (ADS)

    Hao, K.; Si, H.; Fujiwara, H.; Ozawa, T.

    2008-12-01

    The devastated Mw 7.9 Wenchuan earthquake occurred along the steep eastern margin of the Tibetan plateau in Sichuan, China, on 12 May 2008. Over 86,592 people were dead or missing, 374159 injured, and more than 4.8 million homeless. The ruptures possibly occurred over a length of 285 km along the northeast striking Longmen Shan (LMS) thrust belt. In order to study the oversized fault ruptures, existing active faults related and relationships with the damages caused, we conducted field investigations during 4-15 June and 3-9 October 2008, covered about 140km length of LMS faults, including Beichuan(BC), Anxian(AC), Mianzhu, Shifang, Pengzhou, Dujiangyan, Yingxiu (YX) and Wenchuan. On the field investigation we found coseismic surface faults along several profiles perpendicular to the LMS faults. The coseismic surface faults we discovered were at Leigu(L), Hanwang(H), Yinghua(Y), Bailu(BL), Xiaoyudong(X), and Baiyunding (BYD). Of them the maximum vertical displacement reached 4.6m at L, Beichuan County. The uplifting displacements dominated in the southwestern section of the rupture. Moreover, the northwest-striking left-lateral fault was found with horizontal displacement of 2.8m, and vertical of 1.5m as well, at X, Pengzhou City. The left-lateral fault, inversely under-controlled movement of right- lateral fault in the area, showed the complexity of the fault movements. The field results showed the coseismic surface ruptures locally while the overall faults movements and Crust deformation could be understood by the Interferometric SAR(InSAR) technique (NIED, 2008) using data from the Phased Array L-band SAR sensor (PALSAR) equipped on Advanced Land Observing Satellite (ALOS). The larger deformation zones detected by InSAR interferogram occurred with a width of ~30 km in southwestern section, and of ~10km in northeastern section of LMS faults. In the southwestern section, the deformation zone occurred mostly within the existing active faults zones: Guanxian

  16. FROG: Time-series analysis

    NASA Astrophysics Data System (ADS)

    Allan, Alasdair

    2014-06-01

    FROG performs time series analysis and display. It provides a simple user interface for astronomers wanting to do time-domain astrophysics but still offers the powerful features found in packages such as PERIOD (ascl:1406.005). FROG includes a number of tools for manipulation of time series. Among other things, the user can combine individual time series, detrend series (multiple methods) and perform basic arithmetic functions. The data can also be exported directly into the TOPCAT (ascl:1101.010) application for further manipulation if needed.

  17. Energy dissipation of Alfven wave packets deformed by irregular magnetic fields in solar-coronal arches

    NASA Technical Reports Server (NTRS)

    Similon, Philippe L.; Sudan, R. N.

    1989-01-01

    The importance of field line geometry for shear Alfven wave dissipation in coronal arches is demonstrated. An eikonal formulation makes it possible to account for the complicated magnetic geometry typical in coronal loops. An interpretation of Alfven wave resonance is given in terms of gradient steepening, and dissipation efficiencies are studied for two configurations: the well-known slab model with a straight magnetic field, and a new model with stochastic field lines. It is shown that a large fraction of the Alfven wave energy flux can be effectively dissipated in the corona.

  18. Energy dissipation of Alfven wave packets deformed by irregular magnetic fields in solar-coronal arches

    NASA Technical Reports Server (NTRS)

    Similon, Philippe L.; Sudan, R. N.

    1989-01-01

    The importance of field line geometry for shear Alfven wave dissipation in coronal arches is demonstrated. An eikonal formulation makes it possible to account for the complicated magnetic geometry typical in coronal loops. An interpretation of Alfven wave resonance is given in terms of gradient steepening, and dissipation efficiencies are studied for two configurations: the well-known slab model with a straight magnetic field, and a new model with stochastic field lines. It is shown that a large fraction of the Alfven wave energy flux can be effectively dissipated in the corona.

  19. Characterisation of acid-soluble and pepsin-solubilised collagen from frog (Rana nigromaculata) skin.

    PubMed

    Zhang, Junjie; Duan, Rui

    2017-08-01

    As the first vertebrates connecting water and land, frogs must have evolved certain specialisations. To find the difference among the collagens from amphibian, fish and mammal animals, acid-soluble collagen (ASC) and pepsin-solubilised collagen (PSC) from frog skin were isolated and characterised. The yield of PSC (19.59%, dry weight) was higher than that of ASC (1.83%, dry weight). The hydroxyproline-to-protein ratio of frog skin was 8.37%, which was higher than that of carp skin ASC (7.83%) but significantly lower than that of calf skin collagen (10.16%), which was in accordance with the living environment of frog. The denaturation temperature of frog skin collagens was approximately 31.5°C. The SDS-PAGE electrophoresis revealed that ASC and PSC were type I collagens. Fourier transform infrared spectroscopy proved that the ASC and PSC retained their helical structures. The results indicated the properties of frog skin collagen were close to those of skin collagen from freshwater fish. The frog skin collagens can potentially be used in biomaterial and other fields. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Isolation of Laribacter hongkongensis, a novel bacterium associated with gastroenteritis, from Chinese tiger frog.

    PubMed

    Lau, Susanna K P; Lee, Leo C K; Fan, Rachel Y Y; Teng, Jade L L; Tse, Cindy W S; Woo, Patrick C Y; Yuen, Kwok-Yung

    2009-01-31

    Laribacter hongkongensis is a recently discovered novel bacterium associated with community-acquired gastroenteritis. Although the bacterium has been isolated from freshwater fish and natural freshwater environments, it is not known if other freshwater animals could also be a source of L. hongkongensis. In a surveillance study on freshwater food animals (other than fish) in Hong Kong, L. hongkongensis was isolated from eight of 10 Chinese tiger frogs (Hoplobatrachus chinensis), a widespread frog species commonly consumed in China and southeast Asia. The large intestine was the site with the highest recovery rate, followed by the small intestine and stomach. None of the 30 Malaysian prawns, 20 pieces of sand shrimp, 20 Chinese mystery snails or 10 Chinese soft-shelled turtles was found to harbor the bacterium. Among the eight positive frogs, a total of 26 isolates of L. hongkongensis, confirmed by phenotypic tests and PCR, were obtained. As with human, freshwater fish and natural water isolates, a heterogeneous population of L. hongkongensis in frogs was identified by pulsed-field gel electrophoresis, with 6 different patterns among the 26 isolates and a single frog often carrying different strains. The present report represents the first to describe the isolation of L. hongkongensis from amphibians. The high isolation rate and genetic heterogeneity of L. hongkongensis among the Chinese tiger frogs suggested that these animals are also natural reservoir for the bacterium. Caution should be exercised in handling and cooking these frogs.

  1. Quantifying Near-Field Deformation of Large Magnitude Strike-Slip Earthquakes using Optical Image Correlation: Implications for Empirical Earthquake Scaling Laws and Safeguarding the Built Environment

    NASA Astrophysics Data System (ADS)

    Milliner, C. W. D.; Dolan, J. F.; Hollingsworth, J.; Leprince, S.; Ayoub, F.

    2016-12-01

    Measurements of co-seismic deformation from surface rupturing events are an important source of information for faulting mechanics and seismic hazard analysis. However, direct measurements of the near-field surface deformation pattern have proven difficult. Traditional field surveys typically cannot observe the diffuse and subtle inelastic strain accommodated over wide fault-zones, while InSAR data typically decorrelates close to the surface rupture due to high phase gradients leaving 1-2 km wide gaps of data. Using sub-pixel, optical image correlation of pre- and post-event air photos, we quantify the near-field, surface deformation pattern of the 1992 Mw= 7.3 Landers and 1999 Mw = 7.1 Hector Mine earthquakes. This technique allows spatially complete measurement of the surface co-seismic slip along the entire surface rupture, as well as the magnitude and width of distributed deformation. For both events we find our displacement measurements are systematically larger than those from field surveys, indicating the presence of significant distributed, `off-fault' deformation. Here we show that the Landers and Hector Mine earthquakes accommodated 46% and 38% of displacement away from the main primary rupture as off-fault deformation, over a mean shear width of 154 m and 121 m, respectively, with significant spatial variability. We also find positive, yet weak correlations of the magnitude of distributed deformation with the type of near-surface lithology and degree of macroscopic fault zone complexity. We envision additional measurements of future ruptures will better constrain what physical properties of the surface rupture are important controls on the distribution of strain, necessary in order to reliably estimate the amount of expected distributed shear along a given fault segment. Our results have basic implications for the accuracy of empirical scaling relations of earthquake surface ruptures derived from field measurements, understanding apparent discrepancies

  2. Real-time visualisation of deformation fields using speckle interferometry and temporal phase unwrapping

    NASA Astrophysics Data System (ADS)

    Coggrave, C. R.; Huntley, J. M.

    2004-04-01

    A real-time system for analysing data from speckle interferometers, and speckle shearing interferometers, has been developed. Interferograms are continuously recorded by a digital camera at a rate of 60 frames s -1 with temporal phase shifting carried out at the same rate. The images are analysed using a pipeline image processor. With a standard 4-frame phase-shifting algorithm (phase steps of π/2), wrapped phase maps are calculated and displayed at 15 frames s -1. These are unwrapped using a temporal phase unwrapping algorithm to provide a real-time colour-coded display of the relevant displacement component. Each camera pixel (or cluster of pixels) behaves in effect as an independent displacement sensor. The reference speckle interferogram is updated automatically at regular user-defined intervals, allowing arbitrarily large deformations to be measured and errors due to speckle decorrelation to be minimised. The system has been applied to the problem of detecting sub-surface delamination cracks in carbon fibre composite panels.

  3. Near-field deformation of a liquid interface by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Mortagne, C.; Chireux, V.; Ledesma-Alonso, R.; Ogier, M.; Risso, F.; Ondarçuhu, T.; Legendre, D.; Tordjeman, Ph.

    2017-07-01

    We experiment the interaction between a liquid puddle and a spherical probe by Atomic Force Microscopy (AFM) for a probe radius R ranging from 10 nm to 30 μ m . We have developed a new experimental setup by coupling an AFM with a high-speed camera and an inverted optical microscope. Interaction force-distance curves (in contact mode) and frequency shift-distance curves (in frequency modulation mode) are measured for different bulk model liquids for which the probe-liquid Hamaker constant Hp l is known. The experimental results, analyzed in the frame of the theoretical model developed in Phys. Rev. Lett. 108, 106104 (2012), 10.1103/PhysRevLett.108.106104 and Phys. Rev. E 85, 061602 (2012), 10.1103/PhysRevE.85.061602, allow to determine the "jump-to-contact" critical distance dmin below which the liquid jumps and wets the probe. Comparison between theory and experiments shows that the probe-liquid interaction at nanoscale is controlled by the liquid interface deformation. This work shows a very good agreement between the theoretical model and the experiments and paves the way to experimental studies of liquids at the nanoscale.

  4. Effects of particle morphology and spacing on the strain fields in a plastically deforming matrix

    SciTech Connect

    Watt, D.F.; Xu, X.Q.; Lloyd, D.J.

    1996-02-01

    More than 25 models have been created using the ABAQUS three-dimensional non-linear finite element software to reveal the stress and strain distributions around and within particles in a plastically deforming matrix. The effects of particle shape, volume fraction and distribution have been examined. The major effect is that a fiber-like stress distribution is developed in the matrix, linking the particles in the direction of loading, regardless of the variations in geometry or properties. However the stress and strain distributions are altered in detail in a systematic fashion by all these variables. Stress in cubic particles are much higher than those in spherical particles. Hard particles which are closely spaced in the direction of loading develop very large stresses in the region between them on the line of loading, whereas the stresses are not nearly as significantly increased for particles closely spaced in the transverse direction. The variations in the distributions of stress and strain can be explained in a general way by reference to compatibility and equilibrium arguments.

  5. Active control of ultrasonic hearing in frogs.

    PubMed

    Gridi-Papp, Marcos; Feng, Albert S; Shen, Jun-Xian; Yu, Zu-Lin; Rosowski, John J; Narins, Peter M

    2008-08-05

    Vertebrates can modulate the sound levels entering their inner ears in the face of intense external sound or during their own vocalizations. Middle ear muscle contractions restrain the motion of the middle ear ossicles, attenuating the transmission of low-frequency sound and thereby protecting the hair cells in the inner ear. Here we show that the Chinese concave-eared torrent frog, Odorrana tormota, can tune its ears dynamically by closing its normally open Eustachian tubes. Contrary to the belief that the middle ear in frogs permanently communicates with the mouth, O. tormota can close this connection by contraction of the submaxillary and petrohyoid muscles, drastically reducing the air volume behind the eardrums. Mathematical modeling and laser Doppler vibrometry revealed that the reduction of this air volume increases the middle ear impedance, resulting in an up to 20 dB gain in eardrum vibration at high frequencies (10-32 kHz) and 26 dB attenuation at low frequencies (3-10 kHz). Eustachian tube closure was observed in the field during calling and swallowing. Besides a potential role in protecting the inner ear from intense low-frequency sound and high buccal air pressure during calling, this previously unrecognized vertebrate mechanism may unmask the high-frequency calls of this species from the low-frequency stream noise which dominates the environment. This mechanism also protects the thin tympanic membranes from injury during swallowing of live arthropod prey.

  6. Active control of ultrasonic hearing in frogs

    PubMed Central

    Gridi-Papp, Marcos; Feng, Albert S.; Shen, Jun-Xian; Yu, Zu-Lin; Rosowski, John J.; Narins, Peter M.

    2008-01-01

    Vertebrates can modulate the sound levels entering their inner ears in the face of intense external sound or during their own vocalizations. Middle ear muscle contractions restrain the motion of the middle ear ossicles, attenuating the transmission of low-frequency sound and thereby protecting the hair cells in the inner ear. Here we show that the Chinese concave-eared torrent frog, Odorrana tormota, can tune its ears dynamically by closing its normally open Eustachian tubes. Contrary to the belief that the middle ear in frogs permanently communicates with the mouth, O. tormota can close this connection by contraction of the submaxillary and petrohyoid muscles, drastically reducing the air volume behind the eardrums. Mathematical modeling and laser Doppler vibrometry revealed that the reduction of this air volume increases the middle ear impedance, resulting in an up to 20 dB gain in eardrum vibration at high frequencies (10–32 kHz) and 26 dB attenuation at low frequencies (3–10 kHz). Eustachian tube closure was observed in the field during calling and swallowing. Besides a potential role in protecting the inner ear from intense low-frequency sound and high buccal air pressure during calling, this previously unrecognized vertebrate mechanism may unmask the high-frequency calls of this species from the low-frequency stream noise which dominates the environment. This mechanism also protects the thin tympanic membranes from injury during swallowing of live arthropod prey. PMID:18658240

  7. Phase-field-crystal modeling of glass-forming liquids: spanning time scales during vitrification, aging, and deformation.

    PubMed

    Berry, Joel; Grant, Martin

    2014-06-01

    Two essential elements required to generate a glass transition within phase-field-crystal (PFC) models are outlined based on observed freezing behaviors in various models of this class. The central dynamic features of glass formation in simple binary liquids are qualitatively reproduced across 12 orders of magnitude in time by applying a physically motivated time scaling to previous PFC simulation results. New aspects of the equilibrium phase behavior of the same binary model system are also outlined, aging behavior is explored in the moderate and deeply supercooled regimes, and aging exponents are extracted. General features of the elastic and plastic responses of amorphous and crystalline PFC solids under deformation are also compared and contrasted.

  8. FROG - Fingerprinting Genomic Variation Ontology.

    PubMed

    Abinaya, E; Narang, Pankaj; Bhardwaj, Anshu

    2015-01-01

    Genetic variations play a crucial role in differential phenotypic outcomes. Given the complexity in establishing this correlation and the enormous data available today, it is imperative to design machine-readable, efficient methods to store, label, search and analyze this data. A semantic approach, FROG: "FingeRprinting Ontology of Genomic variations" is implemented to label variation data, based on its location, function and interactions. FROG has six levels to describe the variation annotation, namely, chromosome, DNA, RNA, protein, variations and interactions. Each level is a conceptual aggregation of logically connected attributes each of which comprises of various properties for the variant. For example, in chromosome level, one of the attributes is location of variation and which has two properties, allosomes or autosomes. Another attribute is variation kind which has four properties, namely, indel, deletion, insertion, substitution. Likewise, there are 48 attributes and 278 properties to capture the variation annotation across six levels. Each property is then assigned a bit score which in turn leads to generation of a binary fingerprint based on the combination of these properties (mostly taken from existing variation ontologies). FROG is a novel and unique method designed for the purpose of labeling the entire variation data generated till date for efficient storage, search and analysis. A web-based platform is designed as a test case for users to navigate sample datasets and generate fingerprints. The platform is available at http://ab-openlab.csir.res.in/frog.

  9. FROG - Fingerprinting Genomic Variation Ontology

    PubMed Central

    Bhardwaj, Anshu

    2015-01-01

    Genetic variations play a crucial role in differential phenotypic outcomes. Given the complexity in establishing this correlation and the enormous data available today, it is imperative to design machine-readable, efficient methods to store, label, search and analyze this data. A semantic approach, FROG: “FingeRprinting Ontology of Genomic variations” is implemented to label variation data, based on its location, function and interactions. FROG has six levels to describe the variation annotation, namely, chromosome, DNA, RNA, protein, variations and interactions. Each level is a conceptual aggregation of logically connected attributes each of which comprises of various properties for the variant. For example, in chromosome level, one of the attributes is location of variation and which has two properties, allosomes or autosomes. Another attribute is variation kind which has four properties, namely, indel, deletion, insertion, substitution. Likewise, there are 48 attributes and 278 properties to capture the variation annotation across six levels. Each property is then assigned a bit score which in turn leads to generation of a binary fingerprint based on the combination of these properties (mostly taken from existing variation ontologies). FROG is a novel and unique method designed for the purpose of labeling the entire variation data generated till date for efficient storage, search and analysis. A web-based platform is designed as a test case for users to navigate sample datasets and generate fingerprints. The platform is available at http://ab-openlab.csir.res.in/frog. PMID:26244889

  10. Exact and Adaptive Signed Distance Fields Computation for Rigid and Deformable Models on GPUs.

    PubMed

    Liu, Fuchang; Kim, Young J

    2014-05-01

    Most techniques for real-time construction of a signed distance field, whether on a CPU or GPU, involve approximate distances. We use a GPU to build an exact adaptive distance field, constructed from an octree by using the Morton code. We use rectangle-swept spheres to construct a bounding volume hierarchy (BVH) around a triangulated model. To speed up BVH construction, we can use a multi-BVH structure to improve the workload balance between GPU processors. An upper bound on distance to the model provided by the octree itself allows us to reduce the number of BVHs involved in determining the distances from the centers of octree nodes at successively lower levels, prior to an exact distance query involving the remaining BVHs. Distance fields can be constructed 35-64 times as fast as a serial CPU implementation of a similar algorithm, allowing us to simulate a piece of fabric interacting with the Stanford Bunny at 20 frames per second.

  11. Distributed deformation structures in shallow water carbonates subsiding through a simple stress field (Jandaira Formation, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Bertotti, Giovanni; Bisdom, Kevin; Bezerra, Hilario; Reijmer, John; Cazarin, Carol

    2016-04-01

    Despite the scarcity of major deformation structures such as folds and faults, the flat-lying, post-rift shallow water carbonates of the Jandaira Formation (Potiguar Basin, NE Brazil) display well-organized fracture systems distributed of tens of km2. Structures observed in the outcropping carbonates are sub-vertical, generally N-S trending mode I and hybrid veins and barren fractures, sub-vertical roughly E-W trending stylolites and sub-horizontal stylolites. These features developed during subsidence in a simple and constant stress field characterized by, beside gravity, a significant horizontal stress probably of tectonic origin. The corresponding depth curves have different origin and slopes and, therefore, cross each other resulting in position of the principal stresses which change with depth. As a result, the type and amount of fractures affecting subsiding rocks change despite the fact that the far-field stresses remain constant. Following early diagenesis and porosity elimination in the first 100-200m depth, Jandaira carbonates experienced wholesale fracturing at depths of 400-800m resulting in a network of NNW-NE trending fractures partly organized in conjugate sets with a low interfault angle and a sub-vertical intersection, and sub-vertical stylolites roughly perpendicular to the fractures. Intense fluid circulation was activated as a consequence through the carbonates. With increasing subsidence, sub-horizontal stylolites formed providing calcite which precipitated in the open fractures transforming them in veins. The Jandaira formation lost thereby the permeability it had reached during the previous stage. Because of the lack of major deformation, the outcrops of the Jandaira Formation is an excellent analog for carbonate reservoirs in the Middle East, South Atlantic and elsewhere.

  12. Near-field postseismic deformation associated with the 1992 Landers and 1999 Hector Mine, California, earthquakes

    USGS Publications Warehouse

    Savage, J.C.; Svarc, J.L.; Prescott, W.H.

    2003-01-01

    After the Landers earthquake (Mw = 7.3, 1992.489) a linear array of 10 monuments extending about 30 km N50??E on either side of the earthquake rupture plus a nearby offtrend reference monument were surveyed frequently by GPS until 2003.2. The array also spans the rupture of the subsequent Hector Mine earthquake (Mw = 7.1, 1999.792 . The pre-Landers velocities of monuments in the array relative to interior North America were estimated from earlier trilateration and very long baseline interferometry measurements. Except at the reference monument, the post-Landers velocities of the individual monuments in the array relaxed to their preseismic values within 4 years. Following the Hector Mine earthquake the velocities of the monuments relaxed to steady rates within 1 year. Those steady rates for the east components are about equal to the pre-Landers rates as is the steady rate for the north component of the one monument east of the Hector Mine rupture. However, the steady rates for the north components of the 10 monuments west of the rupture are systematically ???10 mm yr1 larger than the pre-Landers rates. The relaxation to a steady rate is approximately exponential with decay times of 0.50 ?? 0.10 year following the Landers earthquake and 0.32 ?? 0.18 year following the Hector Mine earthquake. The postearthquake motions of the Landers array following the Landers earthquake are not well approximated by the viscoelastic-coupling model of Pollitz et al. [2000]. A similar viscoelastic-coupling model [Pollitz et al., 2001] is more successful in representing the deformation after the Hector Mine earthquake.

  13. Research on moving object detection based on frog's eyes

    NASA Astrophysics Data System (ADS)

    Fu, Hongwei; Li, Dongguang; Zhang, Xinyuan

    2008-12-01

    On the basis of object's information processing mechanism with frog's eyes, this paper discussed a bionic detection technology which suitable for object's information processing based on frog's vision. First, the bionics detection theory by imitating frog vision is established, it is an parallel processing mechanism which including pick-up and pretreatment of object's information, parallel separating of digital image, parallel processing, and information synthesis. The computer vision detection system is described to detect moving objects which has special color, special shape, the experiment indicates that it can scheme out the detecting result in the certain interfered background can be detected. A moving objects detection electro-model by imitating biologic vision based on frog's eyes is established, the video simulative signal is digital firstly in this system, then the digital signal is parallel separated by FPGA. IN the parallel processing, the video information can be caught, processed and displayed in the same time, the information fusion is taken by DSP HPI ports, in order to transmit the data which processed by DSP. This system can watch the bigger visual field and get higher image resolution than ordinary monitor systems. In summary, simulative experiments for edge detection of moving object with canny algorithm based on this system indicate that this system can detect the edge of moving objects in real time, the feasibility of bionic model was fully demonstrated in the engineering system, and it laid a solid foundation for the future study of detection technology by imitating biologic vision.

  14. Detection, visualization and animation of abnormal anatomic structure with a deformable probabilistic brain atlas based on random vector field transformations.

    PubMed

    Thompson, P M; Toga, A W

    1997-09-01

    This paper describes the design, implementation and preliminary results of a technique for creating a comprehensive probabilistic atlas of the human brain based on high-dimensional vector field transformations. The goal of the atlas is to detect and quantify distributed patterns of deviation from normal anatomy, in a 3-D brain image from any given subject. The algorithm analyzes a reference population of normal scans and automatically generates color-coded probability maps of the anatomy of new subjects. Given a 3-D brain image of a new subject, the algorithm calculates a set of high-dimensional volumetric maps (with typically 384(2) x 256 x 3 approximately 10(8) degrees of freedom) elastically deforming this scan into structural correspondence with other scans, selected one by one from an anatomic image database. The family of volumetric warps thus constructed encodes statistical properties and directional biases of local anatomical variation throughout the architecture of the brain. A probability space of random transformations, based on the theory of anisotropic Gaussian random fields, is then developed to reflect the observed variability in stereotaxic space of the points whose correspondences are found by the warping algorithm. A complete system of 384(2) x 256 probability density functions is computed, yielding confidence limits in stereotaxic space for the location of every point represented in the 3-D image lattice of the new subject's brain. Color-coded probability maps are generated, densely defined throughout the anatomy of the new subject. These indicate locally the probability of each anatomic point being unusually situated, given the distributions of corresponding points in the scans of normal subjects. 3-D MRI and high-resolution cryosection volumes are analyzed from subjects with metastatic tumors and Alzheimer's disease. Gradual variations and continuous deformations of the underlying anatomy are simulated and their dynamic effects on regional

  15. Crustal deformation and magmatic processes at Laguna del Maule volcanic field (Chile): Geodetic measurements and numerical models

    NASA Astrophysics Data System (ADS)

    Le Mével, Hélène

    The Laguna del Maule (LdM) volcanic field in Chile is an exceptional example of postglacial rhyolitic volcanism in the Southern Volcanic Zone of the Andes. Since 2007, LdM has experienced an unrest episode characterized by high rates of deformation measured by interferometric analysis of synthetic aperture radar (SAR) images acquired between 2007 and 2016, and data from the Global Positioning System (GPS) recorded since 2012 at five stations. The inflating region includes most of the 16--km-by--14--km ring of rhyolitic domes and coulees. The fastest-moving GPS station (MAU2) has a velocity vector of [[special character omited]72 +/- 4, 19 +/- 1, 194 +/- 3] mm/yr between 2012 and 2016 for the eastward, northward, and upward components, respectively. First, we model the InSAR observations assuming a rectangular dislocation in a half space with uniform elastic properties. The best time function for modeling the InSAR data set is a double exponential model with rates increasing from 2007 through 2010 and decreasing slowly since 2011. Modeling of historical uplift at Yellowstone, Long Valley, and Three Sisters volcanic fields suggests a common temporal evolution of vertical displacement rates. We hypothesize that magma intruding into an existing silicic magma reservoir is driving the surface deformation and present a new dynamic model to describe this process. A Newtonian fluid characterized by its viscosity, density, and pressure flows through a vertical conduit, intruding into a reservoir embedded in an elastic domain and leading to time-dependent surface deformation. Using a grid-search optimization, we minimize the misfit to the InSAR displacement data by varying the three parameters governing the analytical solution: the characteristic timescale tauP for magma propagation, the injection pressure, and the inflection time when the acceleration switches from positive to negative. For a spheroid with semi-major axis a = 6200 m, semi-minor axis c = 100 m, located at a

  16. Three-dimensional mechanical modeling of large-scale crustal deformation in China constrained by the GPS velocity field

    NASA Astrophysics Data System (ADS)

    Wang, Jian; Ye, Zheng-Ren; He, Jian-Kun

    2008-01-01

    We present a quantitative model for the crustal movement in China with respect to the Eurasia plate by using the three-dimensional finite element code ADELI. The model consists of an elastoplastic upper lithosphere and a viscoelastic lower lithosphere. The lithosphere is supported by the hydrostatic pressure at its base. The India-Eurasia collision is modeled as a velocity boundary condition. Ten large-scale faults are introduced as Coulomb-type frictional zones in the modeling. The values for the root mean square (RMS) of the east and north velocity components differences (RMS(Ue) and RMS(Un)), which are between the observation and the prediction, are regarded as the measurements to evaluate our simulations. We model the long-term crustal deformation in China by adjusting the faults frictions ranged from 0.01 to 0.5 and considering the effects resulted from lithospheric viscosity variation and topographic loading. Our results suggest most of the large-scale faults frictions are not larger than 0.1, which is consistent with other large-scale faults such as the North Anatolian fault (Provost, A.S., Chery, J., Hassani, R., 2003. Three-dimensional mechanical modeling of the GPS velocity field along the North Anatolian fault. Earth Planet. Sci. Lett. 209, 361-377) and the San Andreas fault (Mount, V.S., Suppe, J., 1987. State of stress near the San Andreas fault: implications for wrench tectonics. Geology, 15, 1143-1146). Further, we examine the effects on the long-term crustal deformation in China of three causes: the large-scale faults, lithospheric viscosity structure and topographic loading. Results indicate that the lithospheric viscosity structure and the topographic loading have important influences on the crustal deformation in China, while the influences caused by the large-scale faults are small. Although our simulations satisfactorily reproduce the general picture of crustal movement in China, there is a poor agreement between the model and the observed GPS

  17. Uniform stress fields inside multiple inclusions in an elastic infinite plane under plane deformation

    PubMed Central

    Dai, Ming; Gao, Cun-Fa; Ru, C. Q.

    2015-01-01

    Multiple elastic inclusions with uniform internal stress fields in an infinite elastic matrix are constructed under given uniform remote in-plane loadings. The method is based on the sufficient and necessary condition imposed on the boundary value of a holomorphic function that guarantees the existence of the holomorphic function in a multiply connected region. The unknown shape of each of the multiple inclusions is characterized by a conformal mapping. This work focuses on a major large class of multiple inclusions characterized by a simple condition that covers and is much beyond the known related results reported in previous works. Extensive examples of multiple inclusions with or without geometrical symmetry are shown. Our results showed that the inclusion shapes obtained for the uniformity of internal stress fields are independent of the remote loading only when all of the multiple inclusions have the same shear modulus as that of the matrix. Moreover, specific conditions are derived on remote loading, elastic constants of the inclusions and uniform internal stress fields, which guarantee the existence of multiple symmetric inclusions or multiple rotationally symmetrical inclusions with uniform internal stress fields. PMID:27547096

  18. Sinusoïdal flow of blood in a cylindrical deformable vessel exposed to an external magnetic field

    NASA Astrophysics Data System (ADS)

    Drochon, Agnès

    2016-03-01

    The present work provides an analytical solution for the Sinusoïdal flow of blood in a cylindrical elastic vessel exposed to an external magnetic field. The vessel is supposed to have non-conducting walls and the induced electric and magnetic fields are neglected. In other words, the well-known calculation of Womersley is revisited through the inclusion of the Lorentz force in the Navier-Stokes equations. A dispersion equation is obtained. This equation admits two types of solutions: the Young waves (mainly associated with radial deformation of the vessel) and the Lamb waves (mainly associated with longitudinal displacements in the vessel wall). It is demonstrated that the external magnetic field has an influence on the wave celerities, on the fluid velocity profiles, and on the wall displacements. It tends to reduce the blood flow and flatten the velocity profile, in the case of Young waves. The pulsatile character of the flow is also dampened. However, these effects become detectable for high values of the Hartmann number (M > 4, corresponding to B0 > 36 T with numerical data pertaining to large human arteries) and remain negligible in the context of magnetic resonance imaging (B0 ≤ 3 T, or even 7 T).

  19. Care and Feeding of Frogs

    NASA Astrophysics Data System (ADS)

    Pan, Margaret; Chiang, Eugene

    2012-01-01

    "Propellers" are features in Saturn's A ring associated with moonlets that open partial gaps. They exhibit non-Keplerian motion (Tiscareno et al.) the longitude residuals of the best-observed propeller, "Blériot," appear consistent with a sinusoid of period ~4 years. Pan & Chiang proposed that propeller moonlets librate in "frog resonances" with co-orbiting ring material. By analogy with the restricted three-body problem, they treated the co-orbital material as stationary in the rotating frame and neglected non-co-orbital material. Here we use simple numerical experiments to extend the frog model, including feedback due to the gap's motion, and drag associated with the Lindblad disk torques that cause Type I migration. Because the moonlet creates the gap, we expect the gap centroid to track the moonlet, but only after a time delay t delay, the time for a ring particle to travel from conjunction with the moonlet to the end of the gap. We find that frog librations can persist only if t delay exceeds the frog libration period P lib, and if damping from Lindblad torques balances driving from co-orbital torques. If t delay Lt P lib, then the libration amplitude damps to zero. In the case of Blériot, the frog resonance model can reproduce the observed libration period P lib ~= 4 yr. However, our simple feedback prescription suggests that Blériot's t delay ~ 0.01P lib, which is inconsistent with the observed libration amplitude of 260 km. We urge more accurate treatments of feedback to test the assumptions of our toy models.

  20. CARE AND FEEDING OF FROGS

    SciTech Connect

    Pan, Margaret; Chiang, Eugene

    2012-01-15

    'Propellers' are features in Saturn's A ring associated with moonlets that open partial gaps. They exhibit non-Keplerian motion (Tiscareno et al.); the longitude residuals of the best-observed propeller, 'Bleriot', appear consistent with a sinusoid of period {approx}4 years. Pan and Chiang proposed that propeller moonlets librate in 'frog resonances' with co-orbiting ring material. By analogy with the restricted three-body problem, they treated the co-orbital material as stationary in the rotating frame and neglected non-co-orbital material. Here we use simple numerical experiments to extend the frog model, including feedback due to the gap's motion, and drag associated with the Lindblad disk torques that cause Type I migration. Because the moonlet creates the gap, we expect the gap centroid to track the moonlet, but only after a time delay t{sub delay}, the time for a ring particle to travel from conjunction with the moonlet to the end of the gap. We find that frog librations can persist only if t{sub delay} exceeds the frog libration period P{sub lib}, and if damping from Lindblad torques balances driving from co-orbital torques. If t{sub delay} << Pl{sub ib}, then the libration amplitude damps to zero. In the case of Bleriot, the frog resonance model can reproduce the observed libration period P{sub lib} {approx_equal} 4 yr. However, our simple feedback prescription suggests that Bleriot's t{sub delay} {approx} 0.01P{sub lib}, which is inconsistent with the observed libration amplitude of 260 km. We urge more accurate treatments of feedback to test the assumptions of our toy models.

  1. Controlling nanowire growth through electric field-induced deformation of the catalyst droplet

    NASA Astrophysics Data System (ADS)

    Panciera, Federico; Norton, Michael M.; Alam, Sardar B.; Hofmann, Stephan; Mølhave, Kristian; Ross, Frances M.

    2016-07-01

    Semiconductor nanowires with precisely controlled structure, and hence well-defined electronic and optical properties, can be grown by self-assembly using the vapour-liquid-solid process. The structure and chemical composition of the growing nanowire is typically determined by global parameters such as source gas pressure, gas composition and growth temperature. Here we describe a more local approach to the control of nanowire structure. We apply an electric field during growth to control nanowire diameter and growth direction. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet. This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and also to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth.

  2. Controlling nanowire growth through electric field-induced deformation of the catalyst droplet

    PubMed Central

    Panciera, Federico; Norton, Michael M.; Alam, Sardar B.; Hofmann, Stephan; Mølhave, Kristian; Ross, Frances M.

    2016-01-01

    Semiconductor nanowires with precisely controlled structure, and hence well-defined electronic and optical properties, can be grown by self-assembly using the vapour–liquid–solid process. The structure and chemical composition of the growing nanowire is typically determined by global parameters such as source gas pressure, gas composition and growth temperature. Here we describe a more local approach to the control of nanowire structure. We apply an electric field during growth to control nanowire diameter and growth direction. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet. This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and also to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth. PMID:27470536

  3. Controlling nanowire growth through electric field-induced deformation of the catalyst droplet.

    PubMed

    Panciera, Federico; Norton, Michael M; Alam, Sardar B; Hofmann, Stephan; Mølhave, Kristian; Ross, Frances M

    2016-07-29

    Semiconductor nanowires with precisely controlled structure, and hence well-defined electronic and optical properties, can be grown by self-assembly using the vapour-liquid-solid process. The structure and chemical composition of the growing nanowire is typically determined by global parameters such as source gas pressure, gas composition and growth temperature. Here we describe a more local approach to the control of nanowire structure. We apply an electric field during growth to control nanowire diameter and growth direction. Growth experiments carried out while imaging within an in situ transmission electron microscope show that the electric field modifies growth by changing the shape, position and contact angle of the catalytic droplet. This droplet engineering can be used to modify nanowires into three dimensional structures, relevant to a range of applications, and also to measure the droplet surface tension, important for quantitative development of strategies to control nanowire growth.

  4. A Phase Field Model of Deformation Twinning: Nonlinear Theory and Numerical Simulations

    DTIC Science & Technology

    2011-03-01

    numerical solutions require advanced computational methods such as level sets [18] for resolution of surfaces of discontinuity. Continuum phase field...conditions (28). Strong forms derived in Sections 2.4 and 3.3 are not needed by the numerical algorithms . Addressed in what follows are the following kinds of...inclusions in Fig. 3) because the algorithm seeks energy minima rather than saddle points. Recall that the total free energy is a non-convex functional

  5. Phase Reconstruction from FROG Using Genetic Algorithms[Frequency-Resolved Optical Gating

    SciTech Connect

    Omenetto, F.G.; Nicholson, J.W.; Funk, D.J.; Taylor, A.J.

    1999-04-12

    The authors describe a new technique for obtaining the phase and electric field from FROG measurements using genetic algorithms. Frequency-Resolved Optical Gating (FROG) has gained prominence as a technique for characterizing ultrashort pulses. FROG consists of a spectrally resolved autocorrelation of the pulse to be measured. Typically a combination of iterative algorithms is used, applying constraints from experimental data, and alternating between the time and frequency domain, in order to retrieve an optical pulse. The authors have developed a new approach to retrieving the intensity and phase from FROG data using a genetic algorithm (GA). A GA is a general parallel search technique that operates on a population of potential solutions simultaneously. Operators in a genetic algorithm, such as crossover, selection, and mutation are based on ideas taken from evolution.

  6. Horizontal and vertical deformation field in New Caledonia, South West Pacific, derived from more than 20 years of GNSS measurements

    NASA Astrophysics Data System (ADS)

    Ballu, V.; Calmant, S.; Valty, P.; Gravelle, M.; Sakic, P.; Aucan, J.; Pelletier, B.

    2015-12-01

    New Caledonia is located in the South West Pacific Ocean, on the Australian Plate just before its subduction under the North Fiji Basin. Because it is on the subducting side of the plate interface, New Caledonia is considered to be stable to first order and not to undergo rapid deformation. However, moderate seismicity is recorded close to the plate interface, in the southern part of the main land and along the Loyalty ridge. In addition, the main island and Loyalty ridge are subjected to long-term vertical deformation due to the flexure of the plate entering subduction. A geodetic network was installed since the early days of GPS (~1990) and has been further developed and occasionally measured since. Due to the low number of global GNSS recording stations in the early 1990s, the positioning accuracy that can be achieved with these data is poor compared to present-day standards, and expected movements are slow (possibly less than 1 mm/yr). However, the >20 year length of the time series may allow us to determine the current deformation field in New Caledonia and Loyalty Ridge. We pay special care in using older GNSS data for characterizing ground motions, reprocessing all available data using a range of different processing strategies and products. We calculated daily positions from double-differenced ionosphere-free carrier phase data in a global network using the GAMIT software and combined and aligned the results on the ITRF2008 using the CATREF software, according to the processing strategy developed as part of the current ULR6 (www.sonel.org) reprocessing campaign for IGS. We compare the double difference results with those obtained in PPP mode using JPL GIPSY software as well as CNES GINS software and different products (MIT, JPL and GRG orbits and clocks provided in the framework of the IGS2 reprocessing campaign). We present both the results for New Caledonia and an analysis of the applicability of these different processing strategies to older GNSS

  7. Development of the pseudothumb in frogs.

    PubMed

    Tokita, Masayoshi; Iwai, Noriko

    2010-08-23

    Frogs have highly conserved hand and foot morphology, possessing four fingers and five toes. As an exception, two Japanese ranid frog species, the Otton frog Babina subaspera and the dagger frog Babina holsti, possess a unique thumb-like structure (the pseudothumb) in the forelimb, giving an appearance of a total of five fingers on the hand. To obtain insights into the developmental mechanisms that generate this novel character, we investigated the hand morphogenesis of the Otton frog. The unique morphological pattern of the pseudothumb was already established in juveniles. Surprisingly, the bud-like structure, which is similar to the area of inductive activity (e.g. feather buds in birds and the carapacial ridge in turtles), was detected over the site where the future prepollex develops in larvae. By contrast, this bud-like structure was not found in larvae of other ranid species. We discuss possible scenarios that would favour the evolution of this very unusual trait in frogs.

  8. Coseismic deformation, field observations and seismic fault of the 17 November 2015 M = 6.5, Lefkada Island, Greece earthquake

    NASA Astrophysics Data System (ADS)

    Ganas, Athanassios; Elias, Panagiotis; Bozionelos, George; Papathanassiou, George; Avallone, Antonio; Papastergios, Asterios; Valkaniotis, Sotirios; Parcharidis, Issaak; Briole, Pierre

    2016-09-01

    On November 17, 2015 07:10:07 UTC a strong, shallow Mw6.5 earthquake, occurred on the island of Lefkada along a strike-slip fault with right-lateral sense of slip. The event triggered widespread environmental effects at the south and western part of the island while, the intensity and severity of these earthquake-induced deformations is substantially decreased towards the eastern part of the island. Relocation of seismicity and inversion of geophysical (GPS, InSAR) data indicate that the seismic fault runs parallel to the west coast of Lefkada, along the Aegean - Apulia plate boundary. The fault plane strikes N20 ± 5°E and dips to east with an angle of about 70 ± 5°. Coseismic deformation was measured in the order of tens of centimeters of horizontal motion by continuous GPS stations of NOANET (the NOA GPS network) and by InSAR (Sentinel 1 A image pairs). A coseismic uniform-slip model was produced from inversion of InSAR data and permanent GPS stations. The earthquake measured Mw = 6.5 using both the geodetic moment produced by the slip model, as well as the PGD relation of Melgar et al. (2015, GRL). In the field we observed no significant vertical motion of the shoreline or surface expression of faulting, this is consistent with the predictions of the model. The interferograms show a large decorrelation area that extends almost along all the western coast of Lefkada. This area correlates well with the mapped landslides. The 2003-2015 pattern of seismicity in the Ionian Sea region indicates the existence of a 15-km seismic gap offshore NW Cephalonia.

  9. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation

    NASA Astrophysics Data System (ADS)

    Reinoso, J.; Paggi, M.; Linder, C.

    2017-02-01

    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  10. Phase field modeling of brittle fracture for enhanced assumed strain shells at large deformations: formulation and finite element implementation

    NASA Astrophysics Data System (ADS)

    Reinoso, J.; Paggi, M.; Linder, C.

    2017-06-01

    Fracture of technological thin-walled components can notably limit the performance of their corresponding engineering systems. With the aim of achieving reliable fracture predictions of thin structures, this work presents a new phase field model of brittle fracture for large deformation analysis of shells relying on a mixed enhanced assumed strain (EAS) formulation. The kinematic description of the shell body is constructed according to the solid shell concept. This enables the use of fully three-dimensional constitutive models for the material. The proposed phase field formulation integrates the use of the (EAS) method to alleviate locking pathologies, especially Poisson thickness and volumetric locking. This technique is further combined with the assumed natural strain method to efficiently derive a locking-free solid shell element. On the computational side, a fully coupled monolithic framework is consistently formulated. Specific details regarding the corresponding finite element formulation and the main aspects associated with its implementation in the general purpose packages FEAP and ABAQUS are addressed. Finally, the applicability of the current strategy is demonstrated through several numerical examples involving different loading conditions, and including linear and nonlinear hyperelastic constitutive models.

  11. A coupled phase-field and volume-of-fluid method for accurate representation of limiting water wave deformation

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Yu, Xiping

    2016-09-01

    A coupled phase-field and volume-of-fluid method is developed to study the sensitive behavior of water waves during breaking. The THINC model is employed to solve the volume-of-fluid function over the entire domain covered by a relatively coarse grid while the phase-field model based on Allen-Cahn equation is applied over the fine grid. A special algorithm that takes into account the sharpness of the diffuse-interface is introduced to correlate the order parameter obtained on the fine grid and the volume-of-fluid function obtained on the coarse grid. The coupled model is then applied to the study of water waves generated by moving pressures on the free surface. The deformation process of the wave crest during the initial stage of breaking is discussed in details. It is shown that there is a significant variation of the free nappe developed at the front side of the wave crest as the wave steepness differs. It is of a plunging type at large wave steepness while of a spilling type at small wave steepness. The numerical results also indicate that breaking occurs later and the duration of breaking is shorter for waves of smaller steepness and vice versa. Neglecting the capillary effect leads to wave breaking with a sharper nappe and a more dynamic plunging process. The surface tension also has an effect to prevent the formation of a free nappe at the front side of the wave crest in some cases.

  12. A Depolarizing Electrogenic Pump in Frog Muscle

    DTIC Science & Technology

    1975-08-01

    mw copy AFRRI SR75-20 AUGUST 1975 AFRRI SCIENTIFIC REPORT O ■ to A DEPOLARIZING ELECTROGENIC PUMP IN FROG MUSCLE D. Geduldig D. R...Academy of Sciences - National Research Council. AFRRI SR75-20 August 1975 A DEPOLARIZING ELECTROGENIC PUMP IN FROG MUSCLE D. GEDULDIG* D. R...INTRODUCTION When Na-enriched frog muscles are bathed in Na- and K-free saline, the small amount of potassium which could accumulate outside of the membrane

  13. HARDENING FROG POINTS BY EXPLOSIVE ENERGY,

    DTIC Science & Technology

    Experiments were made to determine the most efficient method of strain hardening railroad frog points in order to increase their fatigue resistance...Mechanical strain hardening with rolls 40 mm in diameter under a load of 8 tons produced in standard frogs cast from G13L high-manganese steel (AISI...Hadfield steel) a work-hardened surface layer 3-5 mm thick with a hardness of 340 HB. In other experiments, the frogs were hardened by exploding a

  14. Mechanical deformation model of the western United States instantaneous strain-rate field

    USGS Publications Warehouse

    Pollitz, F.F.; Vergnolle, M.

    2006-01-01

    We present a relationship between the long-term fault slip rates and instantaneous velocities as measured by Global Positioning System (GPS) or other geodetic measurements over a short time span. The main elements are the secularly increasing forces imposed by the bounding Pacific and Juan de Fuca (JdF) plates on the North American plate, viscoelastic relaxation following selected large earthquakes occurring on faults that are locked during their respective interseismic periods, and steady slip along creeping portions of faults in the context of a thin-plate system. In detail, the physical model allows separate treatments of faults with known geometry and slip history, faults with incomplete characterization (i.e. fault geometry but not necessarily slip history is available), creeping faults, and dislocation sources distributed between the faults. We model the western United States strain-rate field, derived from 746 GPS velocity vectors, in order to test the importance of the relaxation from historic events and characterize the tectonic forces imposed by the bounding Pacific and JdF plates. Relaxation following major earthquakes (M ??? 8.0) strongly shapes the present strain-rate field over most of the plate boundary zone. Equally important are lateral shear transmitted across the Pacific-North America plate boundary along ???1000 km of the continental shelf, downdip forces distributed along the Cascadia subduction interface, and distributed slip in the lower lithosphere. Post-earthquake relaxation and tectonic forcing, combined with distributed deep slip, constructively interfere near the western margin of the plate boundary zone, producing locally large strain accumulation along the San Andreas fault (SAF) system. However, they destructively interfere further into the plate interior, resulting in smaller and more variable strain accumulation patterns in the eastern part of the plate boundary zone. Much of the right-lateral strain accumulation along the SAF

  15. Deformation near the Casa Diablo geothermal well field and related processes Long Valley caldera, Eastern California, 1993-2000

    USGS Publications Warehouse

    Howle, J.F.; Langbein, J.O.; Farrar, C.D.; Wilkinson, S.K.

    2003-01-01

    Regional first-order leveling lines, which extend from Lee Vining, CA, to Tom's Place, CA, have been surveyed periodically since 1957 by the U.S. Geological Survey (USGS), the National Geodetic Survey (NGS), and Caltrans. Two of the regional survey lines, or leveling networks, intersect at the Casa Diablo geothermal well field. These leveling networks, referenced to a distant bench mark (C916) near Lee Vining, provide time-series vertical control data of land-surface deformation that began around 1980. These data are also useful for delineating localized subsidence at Casa Diablo related to reservoir pressure and temperature changes owing to geothermal development that began in 1985. A comparison of differences in bench-mark elevations for five time periods between 1983 and 1997 shows the development and expansion of a subsidence bowl at Casa Diablo. The subsidence coincides spatially with the geothermal well field and temporally with the increased production rates and the deepening of injection wells in 1991, which resulted in an increase in the rate of pressure decline. The subsidence, superimposed on a broad area of uplift, totaled about 310 mm by 1997. The USGS established orthogonal tilt arrays in 1983 to better monitor deformation across the caldera. One tilt array (DBR) was established near what would later become the Casa Diablo geothermal well field. This array responded to magmatic intrusions prior to geothermal development, tilting away from the well field. With the start of geothermal fluid extraction in 1985, tilt at the DBR array reversed direction and began tilting into the well field. In 1991, geothermal power production was increased by a factor of four, and reservoir pressures began a period of steep decline. These changes caused a temporary three-fold increase in the tilt rate. The tilt rate became stable in 1993 and was about 40% lower than that measured in 1991-1992, but still greater than the rates measured during 1985-1990. Data from the

  16. Stress heterogeneities in anisotropic materials - their effect on dislocation fields and post-deformational recrystallization: Insights from combined experiments and numerical simulations of polycrystalline ice

    NASA Astrophysics Data System (ADS)

    Piazolo, S.; Montagnat, M.; Borthwick, V.; Evans, L.; Griera, A.; Grennerat, F.; Moulinec, H.; Wheeler, J.

    2014-12-01

    We present a coupled experimental and modeling approach to better understand the role of stress field heterogeneities on deformation and post-deformational behavior in material with a high viscoplastic anisotropy e.g. polycrystalline ice. We investigate: (1) Effect of stress heterogeneities on deformation behavior and microstructural development and, (2) effect of such microstructures on post-deformational recrystallization. (1) Full-field elasto-viscoplastic modelling (CraFT) is used to predict the local stress and strain field during transient creep in a polycrystalline ice sample. Modeling input includes the experimental starting microstructure and a validated slip system dependent flow law. EBSD measurements on selected areas are used to estimate the local dislocation field utilizing the Weighted Burgers Vector (WBV) analysis. Areas of local stress concentration correlate with triple junctions and grain boundaries, originating from strain incompatibilities between differently oriented grains. In these areas, the WBV analysis shows a non-negligible c-axis component that must be related to resolved shear stress in a prismatic plane, coherent with the predicted elevated stress levels. The resultant defect structure is necessary for the formation of the observed kink bands which have a well-defined crystallographic character, lattice distortions and subgrain development. (2) The microstructures arising from (1) significantly affect post-deformational behavior. Combined post-deformational annealing experiments and numerical simulations using the microdynamic modeling platform ELLE, allow prediction of the local microstructural evolution taking recovery within grains, grain boundary migration and nucleation into account. Results from this study, can explain several of the observed features in natural ice, and help to refine large scale models.

  17. The husbandry and care of dendrobatid frogs.

    PubMed

    St Claire, Mark B; Kennett, Mary J; Thomas, Marvin L; Daly, John W

    2005-11-01

    Dendrobatid frogs are studied primarily for the bioactive alkaloids found in their skin. Also known as poison-dart frogs, these animals accumulate toxic alkaloids from dietary sources. The function and uses of the many alkaloids, the alkaloid accumulation system, and the basic biology and physiology of the frogs themselves are of research interest. Here we overview the taxonomy of these frogs and some of the unique aspects of their natural biology and reproduction. We also describe the components of a successful laboratory housing system, including temperature, lighting, humidity, ventilation, nutrition, health considerations, and handling. A brief summary of dendrobatid research highlights is provided.

  18. Modification of the malus law for the torsional deformation of lyotropic nematics in magnetic field on the basis of statistical approach

    NASA Astrophysics Data System (ADS)

    Golovanov, A. V.; Shapovalov, V. I.

    2010-07-01

    A method based on the statistical approach is proposed to calculate the light intensity for the torsional deformation of lyotropic nematic liquid crystals at violated Mauguin adiabatic approximation. Theoretical dependences of the light intensity on the magnetic field strength are obtained for two limiting cases of lyotropic nematic anchoring with bearing surfaces: infinite and low anchoring energies.

  19. Observations of deformation and mixing of the total ozone field in the Antaractic Polar Vortex

    SciTech Connect

    Bowman, K.P. ); Mangus, N.J. )

    1993-09-01

    Total Ozone Mapping Spectrometer (TOMS) images of the springtime Southern Hemisphere commonly show concentric layers in the total ozone field outside the Antarctic polar vortex. The layering appears to result from horizontal folding and stretching of regions on the equatorward flank of the polar vortex near the midlatitude ozone maximum. This folding and stretching interleaves low and high ozone air from the subtropics and midlatitudes, respectively. Occasional large amplitude wave events can extract very low ozone air from the interior of the polar vortex (the Antarctic ozone hole), but the folding and stretching results in relatively rapid horizontal mixing of the atmosphere on the equatorward flank of the jet. This type of lagrangian behavior may be common in the atmosphere, but is only visible when local tracer gradients are large and observations with high spatial resolution are available. Also, experimentation has shown that gray-scale images of TOMS data show the details of the spatial distribution of ozone much more clearly than contour maps of false-color images. 22 refs., 3 figs., 2 tabs.

  20. Deformation of the total ozone content field in the tropical zone

    NASA Technical Reports Server (NTRS)

    Vasilyev, Victor I.

    1994-01-01

    Presented are the ozone investigation results obtained in the tropical zone. Measurements of the total ozone content (TOC) were carried out by the ozonometer M-124. The ozonometer was automated to investigate the ozone intradiurnal variations and to increase precision of the TOC measurements. Obtained results allowed us to follow the effect of tropical cyclones (TC) on the TOC field. Several days before the TC formation the TOC increase is observed in daily mean course compared with the background one. Three types of trend can be singled out in the TOC intradiurnal course: zero, parabolic, quasi-linear. Maximum velocities of a trend are observed some days before the TC formation. Analogous harmonic constituents are mainly presented as spectrum of daily means of ozone, mean and absolute velocities of trend and dispersion as well as spectra of meteorological, hydrometeorological and actinometric values. Revealed is a number of day-to-day ozone variations concerned with large-scale circulations; moisture content in the atmosphere. Obtained are the data about short-period ozone waves (period less than a day). Thin-film silver sensors were used to measure the vertical ozone distribution (VOD). Atmospheric aerosol and VOD measurements were carried out simultaneously, they gave data of the VOD layered structure, where the VOD local minima coincided with the position of aerosol layers' maxima.

  1. Naturally occurring fluorescence in frogs

    PubMed Central

    Taboada, Carlos; Brunetti, Andrés E.; Pedron, Federico N.; Carnevale Neto, Fausto; Estrin, Darío A.; Bari, Sara E.; Chemes, Lucía B.; Peporine Lopes, Norberto; Lagorio, María G.

    2017-01-01

    Fluorescence, the absorption of short-wavelength electromagnetic radiation reemitted at longer wavelengths, has been suggested to play several biological roles in metazoans. This phenomenon is uncommon in tetrapods, being restricted mostly to parrots and marine turtles. We report fluorescence in amphibians, in the tree frog Hypsiboas punctatus, showing that fluorescence in living frogs is produced by a combination of lymph and glandular emission, with pigmentary cell filtering in the skin. The chemical origin of fluorescence was traced to a class of fluorescent compounds derived from dihydroisoquinolinone, here named hyloins. We show that fluorescence contributes 18−29% of the total emerging light under twilight and nocturnal scenarios, largely enhancing brightness of the individuals and matching the sensitivity of night vision in amphibians. These results introduce an unprecedented source of pigmentation in amphibians and highlight the potential relevance of fluorescence in visual perception in terrestrial environments. PMID:28289227

  2. Naturally occurring fluorescence in frogs.

    PubMed

    Taboada, Carlos; Brunetti, Andrés E; Pedron, Federico N; Carnevale Neto, Fausto; Estrin, Darío A; Bari, Sara E; Chemes, Lucía B; Peporine Lopes, Norberto; Lagorio, María G; Faivovich, Julián

    2017-04-04

    Fluorescence, the absorption of short-wavelength electromagnetic radiation reemitted at longer wavelengths, has been suggested to play several biological roles in metazoans. This phenomenon is uncommon in tetrapods, being restricted mostly to parrots and marine turtles. We report fluorescence in amphibians, in the tree frog Hypsiboas punctatus, showing that fluorescence in living frogs is produced by a combination of lymph and glandular emission, with pigmentary cell filtering in the skin. The chemical origin of fluorescence was traced to a class of fluorescent compounds derived from dihydroisoquinolinone, here named hyloins. We show that fluorescence contributes 18-29% of the total emerging light under twilight and nocturnal scenarios, largely enhancing brightness of the individuals and matching the sensitivity of night vision in amphibians. These results introduce an unprecedented source of pigmentation in amphibians and highlight the potential relevance of fluorescence in visual perception in terrestrial environments.

  3. Ionic conductivity, structural deformation, and programmable anisotropy of DNA origami in electric field.

    PubMed

    Li, Chen-Yu; Hemmig, Elisa A; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia; Keyser, Ulrich F; Aksimentiev, Aleksei

    2015-02-24

    The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules, a DNA origami plate, placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg(2+) ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA.

  4. Ionic Conductivity, Structural Deformation and Programmable Anisotropy of DNA Origami in Electric Field

    PubMed Central

    Li, Chen-Yu; Hemmig, Elisa A.; Kong, Jinglin; Yoo, Jejoong; Hernández-Ainsa, Silvia

    2015-01-01

    The DNA origami technique can enable functionalization of inorganic structures for single-molecule electric current recordings. Experiments have shown that several layers of DNA molecules—a DNA origami plate— placed on top of a solid-state nanopore is permeable to ions. Here, we report a comprehensive characterization of the ionic conductivity of DNA origami plates by means of all-atom molecular dynamics (MD) simulations and nanocapillary electric current recordings. Using the MD method, we characterize the ionic conductivity of several origami constructs, revealing the local distribution of ions, the distribution of the electrostatic potential and contribution of different molecular species to the current. The simulations determine the dependence of the ionic conductivity on the applied voltage, the number of DNA layers, the nucleotide content and the lattice type of the plates. We demonstrate that increasing the concentration of Mg2+ ions makes the origami plates more compact, reducing their conductivity. The conductance of a DNA origami plate on top of a solid-state nanopore is determined by the two competing effects: bending of the DNA origami plate that reduces the current and separation of the DNA origami layers that increases the current. The latter is produced by the electro-osmotic flow and is reversible at the time scale of a hundred nanoseconds. The conductance of a DNA origami object is found to depend on its orientation, reaching maximum when the electric field aligns with the direction of the DNA helices. Our work demonstrates feasibility of programming the electrical properties of a self-assembled nanoscale object using DNA. PMID:25623807

  5. Two-dimensional shear bands growing dynamically in plates: An investigation of transient deformation fields, temperature fields and shear band toughness

    SciTech Connect

    Rosakis, A.J.

    1995-12-31

    The phenomenon of dynamic initiation and propagation of two-dimensional adiabatic shear bands is experimentally and numerically investigated. Prenotched metal plates are subjected to asymmetric impact load histories (dynamic mode-II loading). Dynamic shear bands emanate from the notch-tip and propagate rapidly in a direction nearly parallel to the direction of impact. Real time temperature histories along a line intersecting and perpendicular to the shear band paths are recorded by means of a high speed infrared detector system. The materials studied are C-300 (a maraging steel), HY-100 steel and Ti-6Al-4V. Experiments show that the peak temperatures inside the propagating shear bands are approaching 90% of the melting point for C-300 and are significantly lower for the titanium alloy (up to 6000C). Additionally, measured distances of shear band propagation indicate stronger resistance to shear banding by HY-100 steel and Ti-6Al-4V. Deformation fields around the propagating shear band are recorded using high speed photography. Shear band speeds are found to strongly depend on impact velocity are as high as 1200 m/s for C-300 steel. Finite element simulations of the experiment are carried out under the context of plane strain, considering finite deformations, inertia, heat conduction, thermal softening, strain hardening and strain-rate hardening. In the simulations, the shear band propagation is assumed to be governed by a critical plastic strain criterion. The results are compared with experimental measurements obtained using the high speed infrared detectors and high speed photography. Finally, the numerical calculations are used to investigate motions of shear band toughness. The shear band driving force is calculated as a function of shear band velocity and compared to the crack driving force versus velocity relations for mode-I, opening cracks in the same material.

  6. Full-field wing deformation measurement scheme for in-flight cantilever monoplane based on 3D digital image correlation

    NASA Astrophysics Data System (ADS)

    Li, Lei-Gang; Liang, Jin; Guo, Xiang; Guo, Cheng; Hu, Hao; Tang, Zheng-Zong

    2014-06-01

    In this paper, a new non-contact scheme, based on 3D digital image correlation technology, is presented to measure the full-field wing deformation of in-flight cantilever monoplanes. Because of the special structure of the cantilever wing, two conjugated camera groups, which are rigidly connected and calibrated to an ensemble respectively, are installed onto the vertical fin of the aircraft and record the whole measurement. First, a type of pre-stretched target and speckle pattern are designed to adapt the oblique camera view for accurate detection and correlation. Then, because the measurement cameras are swinging with the aircraft vertical trail all the time, a camera position self-correction method (using control targets sprayed on the back of the aircraft), is designed to orientate all the cameras’ exterior parameters to a unified coordinate system in real time. Besides, for the excessively inclined camera axis and the vertical camera arrangement, a weak correlation between the high position image and low position image occurs. In this paper, a new dual-temporal efficient matching method, combining the principle of seed point spreading, is proposed to achieve the matching of weak correlated images. A novel system is developed and a simulation test in the laboratory was carried out to verify the proposed scheme.

  7. Ultrafast structural deformation of NO2 in intense laser fields studied by mass-resolved momentum imaging

    NASA Astrophysics Data System (ADS)

    Hishikawa, Akiyoshi; Iwamae, Atsushi; Yamanouchi, Kaoru

    1999-11-01

    The ultrafast structural deformation of NO2 in an intense laser field (1.0 PW/cm2) is studied by mass-resolved momentum imaging (MRMI) of the Op+ and Nq+ (p,q=1-3) fragment ions produced from NO2z+ through the Coulomb explosion processes, NO2z+→Op++Nq++Or+ (z=p+q+r). The N-O distance just before the Coulomb explosion is elongated significantly from that in the electronic ground state, and it monotonically increases from 1.7 to 2.1 Å as z increases from 4 to 9. The ∠O-N-O bond angle increases toward a linear configuration as a function of z, which is interpreted in terms of the formation of the light-dressed potential energy surfaces. The two-body fragmentation pathways to produce NO+ and NO2+ are also investigated by the MRMI measurements to derive the extent of the asymmetrical bond elongation of one of the two N-O bonds.

  8. Constraints on current crustal deformation of the Taiwan plate boundary from CGPS strain rate field and focal mechanism stress inversions

    NASA Astrophysics Data System (ADS)

    Chen, K.; Wu, Y.; Hsu, Y.; Chan, Y.

    2013-12-01

    There are many studies using the continuous GPS (CGPS) observations and forward modeling to represent the current crustal deformation around the global plate boundaries. However, the relation between surface geodetic data and crustal deformation is still a major debate since there are only few available data at depth for constraints. In this study, 3D spatial variations of interseismic surface strain rate and crustal stress state in Taiwan are evaluated by using both CGPS data and earthquake focal mechanisms from 1994 to 2010 and 1991 to 2010, respectively. We estimated strain rate with a simple approach that solves for surface velocity on a 0.1 x 0.1° grid while weighting the distance between observations and each grid node. The surface velocities used in this study are after the process of removing the coseismic and postseismic effects caused by local main shocks. We applied the genetic algorithm in a nonlinear global search for the focal mechanism solution determination with magnitude ranging from ML 1.6 to 7.3 by first motion polarities of P waves. Earthquakes were excluded the redundant aftershock sequences which perturbed the estimation of interseismic stress state. There are 7083 events determined around Taiwan for performing a stress tensor inversion. In the comparison of orientations between strain rate and stress axes, we found the regional variation of stress orientations from surface to the base of crust is significant and not homogenous in Taiwan. In general, the orientations of strain rate and stress axes are consistent from surface to 20 km depth in most of Taiwan regimes. We suggest that the common decoupling phenomenon between both axes starts from 20 km implying a rheological change. The consistency of orientations from strain rate and stress field extends from surface down to more than 30 km in Central Taiwan and southern Coastal Range (COR) could be associated with stress accumulation in the crust for the 1999 Mw 7.6 Chi-Chi and 2003 Mw 6

  9. A comparative analysis of frog early development

    PubMed Central

    del Pino, Eugenia M.; Venegas-Ferrín, Michael; Romero-Carvajal, Andrés; Montenegro-Larrea, Paola; Sáenz-Ponce, Natalia; Moya, Iván M.; Alarcón, Ingrid; Sudou, Norihiro; Yamamoto, Shinji; Taira, Masanori

    2007-01-01

    The current understanding of Xenopus laevis development provides a comparative background for the analysis of frog developmental modes. Our analysis of development in various frogs reveals that the mode of gastrulation is associated with developmental rate and is unrelated to egg size. In the gastrula of the rapidly developing embryos of the foam-nesting frogs Engystomops coloradorum and Engystomops randi, archenteron and notochord elongation overlapped with involution at the blastopore lip, as in X. laevis embryos. In embryos of dendrobatid frogs and in the frog without tadpoles Eleutherodactylus coqui, which develop somewhat more slowly than X. laevis, involution and archenteron elongation concomitantly occurred during gastrulation; whereas elongation of the notochord and, therefore, dorsal convergence and extension, occurred in the postgastrula. In contrast, in the slow developing embryos of the marsupial frog Gastrotheca riobambae, only involution occurred during gastrulation. The processes of archenteron and notochord elongation and convergence and extension were postgastrulation events. We produced an Ab against the homeodomain protein Lim1 from X. laevis as a tool for the comparative analysis of development. By the expression of Lim1, we were able to identify the dorsal side of the G. riobambae early gastrula, which otherwise was difficult to detect. Moreover, the Lim1 expression in the dorsal lip of the blastopore and notochord differed among the studied frogs, indicating variation in the timing of developmental events. The variation encountered gives evidence of the modular character of frog gastrulation. PMID:17606898

  10. The Ups and Downs of Frogs.

    ERIC Educational Resources Information Center

    Greene, Janice Schnake; Tamme, Tina

    2001-01-01

    Presents a science activity in which students simulate increases and decreases in frog populations to get a better understanding of different environmental issues affecting animal populations. Includes simulations for both natural frog populations as well as populations affected by human activities. (YDS)

  11. Semi-automated identification of leopard frogs

    USGS Publications Warehouse

    Petrovska-Delacrétaz, Dijana; Edwards, Aaron; Chiasson, John; Chollet, Gérard; Pilliod, David S.

    2014-01-01

    Principal component analysis is used to implement a semi-automatic recognition system to identify recaptured northern leopard frogs (Lithobates pipiens). Results of both open set and closed set experiments are given. The presented algorithm is shown to provide accurate identification of 209 individual leopard frogs from a total set of 1386 images.

  12. The Ups and Downs of Frogs.

    ERIC Educational Resources Information Center

    Greene, Janice Schnake; Tamme, Tina

    2001-01-01

    Presents a science activity in which students simulate increases and decreases in frog populations to get a better understanding of different environmental issues affecting animal populations. Includes simulations for both natural frog populations as well as populations affected by human activities. (YDS)

  13. Speciation: frog mimics prefer their own.

    PubMed

    Mallet, James

    2014-11-17

    Ranitomeya poison frogs in the Peruvian Amazon are a rare example of Müllerian mimicry in vertebrates. These frogs also prefer to court same-coloured mimics. This suggests that divergence in mimicry plays a role in reproductive isolation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Crustal deformation

    NASA Astrophysics Data System (ADS)

    Larson, Kristine M.

    1995-07-01

    Geodetic measurements of crustal deformation provide direct tests of geophysical models which are used to describe the dynamics of the Earth. Although geodetic observations have been made throughout history, only in the last several hundred years have they been sufficiently precise for geophysical studies. In the 19th century, these techniques included leveling and triangulation. Approximately 25 years ago, trilateration measurements were initiated by the USGS (United States Geological Survey) to monitor active faults in the United States. Several years later, NASA (National Aeronautics and Space Administration) begin an effort to measure plate tectonic motions on a global scale, using space geodetic techniques, VLBI (Very Long Baseline Interferometry) and SLR (Satellite Laser Ranging). The period covered by this report to the IUGG, 1991-1994, was a transition period in the field of crustal deformation. Trilateration measurements (previously the backbone of measurements across plate boundaries in the western United States and Alaska) have been abandoned. This system was labor-intensive, involved highly trained crews to carry out the observations, and only measured the length between sites. In addition, NASA drastically cut the budgets for VLBI and SLR during this period. Fixed site VLBI systems are still operational, but mobile VLBI measurements in North America have ceased. SLR measurements continue on a global scale, but the remaining crustal deformation measurements are now being made with the Global Positioning System (GPS). Nonetheless, because of the time scales involved, older geodetic data (including leveling, triangulation, and trilateration) continue to be important for many geophysical studies.

  15. Time-Dependent Deformation at Brady Hot Springs Geothermal Field (Nevada) Measured With Interferometric Synthetic Aperture Radar and Modeled with Multiple Working Hypotheses of Coupled Behavior

    NASA Astrophysics Data System (ADS)

    Feigl, K. L.; Ali, S. T.; Akerley, J.; Baluyut, E.; Cardiff, M. A.; Davatzes, N. C.; Foxall, W.; Fratta, D.; Kreemer, C.; Mellors, R. J.; Lopeman, J.; Spielman, P.; Wang, H. F.

    2015-12-01

    To measure time-dependent deformation at the Brady Hot Springs geothermal field in western Nevada, we analyze interferometric synthetic aperture radar (InSAR) data acquired between 2004 and 2014 by five satellite missions, including: ERS-2, Envisat, ALOS, TerraSAR-X, and TanDEM-X. The resulting maps of deformation show an elliptical subsiding area that is ~4 km by ~1.5 km. Its long axis coincides with the strike of the dominant normal-fault system at Brady. Within this bowl of subsidence, the interference pattern shows several smaller features with length scales of the order of ~1 km. This signature occurs consistently in all of the well-correlated interferometric pairs spanning several months. Results from inverse modeling suggest that the deformation is a result of volumetric contraction in shallow units, no deeper than 600 m, that are probably associated with damaged regions where faults interact via thermal (T), hydrological (H), mechanical (M), and chemical (C) processes. Such damaged zones are expected to extend downward along steeply dipping fault planes, providing high-permeability conduits to the production wells. Using time series analysis, we test the hypothesis that geothermal production drives the observed deformation. We find a good correlation between the observed deformation rate and the rate of production in the shallow wells. We explore first-order models to calculate the time-dependent deformation fields produced by coupled processes, including: thermal contraction of rock (T-M coupling), decline in pore pressure (H-M coupling), and dissolution of minerals over time (H-C-M coupling). These processes are related to the heterogeneity of hydro-geological and material properties at the site. This work is part of a project entitled "Poroelastic Tomography by Adjoint Inverse Modeling of Data from Seismology, Geodesy, and Hydrology" (PoroTomo) http://geoscience.wisc.edu/feigl/porotomo.

  16. Dependence of near field co-seismic ionospheric perturbations on surface deformations: A case study based on the April, 25 2015 Gorkha Nepal earthquake

    NASA Astrophysics Data System (ADS)

    Sunil, A. S.; Bagiya, Mala S.; Catherine, Joshi; Rolland, Lucie; Sharma, Nitin; Sunil, P. S.; Ramesh, D. S.

    2017-03-01

    Ionospheric response to the recent 25 April 2015 Gorkha, Nepal earthquake is studied in terms of Global Positioning System-Total Electron Content (GPS-TEC) from the viewpoints of source directivity, rupture propagation and associated surface deformations, over and near the fault plane. The azimuthal directivity of co-seismic ionospheric perturbations (CIP) amplitudes from near field exhibit excellent correlation with east-southeast propagation of earthquake rupture and associated surface deformations. In addition, the amplitude of CIP is observed to be very small in the opposite direction of the rupture movement. Conceptual explanations on the poleward directivity of CIP exist in literature, we show the observational evidences of additional equator ward directivity, interpreted in terms of rupture propagation direction. We also discuss the coupling between earthquake induced acoustic waves and local geomagnetic field and its effects on near field CIP amplitudes. We suggest that variability of near field CIP over and near the fault plane are the manifestations of the geomagnetic field-wave coupling in addition to crustal deformations that observed through GPS measurements and corroborated by Interferometric Synthetic Aperture Radar (InSAR) data sets.

  17. The Cenozoic stress/deformation field of the Donets coal basin and Northern Azov region and its probable sources

    NASA Astrophysics Data System (ADS)

    Kopp, M.; Korchemagin, V.; Kolesnichenko, A.

    2009-04-01

    Studies of structure, development and dynamics of formation of the little-investigated Cenozoic (Alpine) deformations of the Donets Herzinic intraplate orogen (Donets Coal Basin, or Donbass) and Northern Azov region, which were accompanied by mass mesotectonic measurement, revealed traces of two independent Cenozoic orogenies: the Laramic one of the Early Alpine (Latest Cretaceous — Paleocene), and the Recent one of the Late Alpine (Neogene — Quaternary). The orogenies differ in area of manifestation and peculiarities of stress/deformation field. The first orogeny in its pure state developed only in the western Donbass and adjacent relic part of the Dnieper-Donets aulacogene where gentle folds of the Mesozoic strata of the WNW - ESE strike were formed. The folds (so-called Izyum-Kramatorsk structural unit) are sharply overprinted by the Eocene beds and confined to salt diapirs gradually uplifting from the Devonian. According the mesotectonic data, in the post-Cretaceous time they however developed under slight transversal compression with some horizontal shear. The Laramic movements occurred also to the east where they together with the Recent ones participated in formation of the Severodonetskij and Persianovskij border reverse faults of the Donbass. However, as a whole the Recent orogeny developed independently and far to the east of the Laramic one. The Donets-North Azov neotectonic swell which appeared at that time occupies not only the eastern Donets intraplate orogen arised from the Dnieper-Donets aulacogene but strongly crosses the southern aulacogene border extending far into the Ukrainian shield. The different areas of the Laramic and Recent orogenic movements in the Donbass suggest that they raised from different sources. The eastern distribution of the Late Alpine deformation and its more intense manifestation (the well noticeable neotectonic uplift as well as the extension outside the aulacogene and the activization of the Ukrainian shield basement

  18. The effect of magnetic field annealing on the texture of 2nd recrystallization for a deformed Fe-3.2% Si steel sheet

    NASA Astrophysics Data System (ADS)

    Kim, Byung Geol; Part, Su Dong; Kim, Shang Shu

    2004-12-01

    The effects of deformation on 2nd recrystallization behavior with or without magnetic field for a 1st recrystallized electrical steel sheet have been investigated. Annealing temperatures (800, 1000 °C) and cold-rolling rates (50, 70 %) were experimental parameters. A magnetic field of 5 T using a superconducting magnet at a heating rate of 15 °C/min was applied in a direction parallel to the rolling direction. The intensity of α-fiber was increased due to the deformation and, in particular, the formation of {100}<110> component was tremendous. Considerable formation of {001}<100> component was also found. At 800 °C, α-fiber was developed rapidly due to deformation, and η-fiber was also formed in the components {100}<100> and {110}<100> The effect of magnetic field annealing was more significant at 800 °C, while the effect at 1000 °C was negligible. These results are discussed in a phenomenological context considering the atomic fluctuation and magnetic induction depending on annealing temperature and magnetic field.

  19. Population density of tropical forest frogs: relation to retreat sites.

    PubMed

    Stewart, M M; Pough, F H

    1983-08-05

    The forest frog Eleutherodactylus coqui defends specific sites for retreats and nests in the Luquillo Forest, Puerto Rico. The hypothesis that shortages of nest and retreat sites limit population size was tested by placing 100 bamboo frog houses in plots measuring 100 square meters in areas of high frog density. These new sites were readily adopted by adult frogs. After one year, experimental plots had significantly more nests and frogs of all sizes than did control plots.

  20. Numerical modeling of deformation and stress fields around a magma chamber: Constraints on failure conditions and rheology

    NASA Astrophysics Data System (ADS)

    Currenti, Gilda; Williams, Charles A.

    2014-01-01

    We present a stress-strain analysis using the Finite Element Method to investigate failure conditions of pressured magma chambers embedded in an inelastic domain. The pressure build-up induces variations in the stress field until failure conditions are reached. Therefore, the definition of the failure conditions could have a significant impact on the volcano hazard assessment. Using a numerical approach, we analyze the stresses in a gravitationally loaded model assuming a brittle failure criterion, to determine the favorable conditions for magma chamber failure in different source geometries, reference stress states, pore fluid pressures, rock rheologies and topographic profiles. The numerical results allow us to pinpoint the conditions promoting seismicity near the magma chamber. The methodology places a limit on the pressure that a magma chamber can sustain before failing and provides a quantitative estimate of the uplift expected at the ground surface. Thermally-activated ductile regimes, which may develop in the region surrounding a heated magma chamber, are also investigated. The stress relaxation in a ductile shell may prevent the wall rupture, favoring the growth of large overpressured chambers, which could lead to considerable deformation at the ground surface without significant seismicity. The numerical results suggest that a spherical source, compressive regime, gentle edifice topography, and growth of a ductile shell are important factors for the initial formation and the mechanical stability of magma storage systems. On the other hand, an elongated ellipsoidal source, extensional regime, steep volcano topography and high pore fluid pressure lower the overpressure necessary for inducing failure. These findings could help in gaining insights on the internal state of the volcano and, hence, in advancing the assessment of the likelihood of volcano unrest.

  1. Paleomagnetic Study of a Miocene Deformation in a Region Close to the Camargo Volcanic Field, Chihuahua, Mexico

    NASA Astrophysics Data System (ADS)

    Wogau-Chong, K.; Bohnel, H.; Aranda Gomez, J.

    2009-05-01

    The Sierra the Aguachile is a Miocene volcanic sequence located in the SE of Chihuahua State NW of the Camargo volcanic field and belongs to the Agua Mayo Group, which unconformably overlays Mesozoic calcareous units. The Sierra de Aguachile sequence defines a structure that may be interpreted as a plunging fold, which could be the result of a reactivation of the San Marcos Fault. This major fault is well known more to the east but may extend into the study area where it would be covered by the younger volcanic sequences; its main activity has been reported to be during the the Neocomian with reactivation phases in the Paleogene and Miocene. To test if the observed structure is the result of a tectonic deformation that happened after the emplacement of the volcanic sequence, a paleomagnetic study was carried out. A total of 14 sites were sampled from different parts of the structure, all in the capping ignimbrite layers. Site mean directions were determined using AF demagnetization. The fold test was applied to analyze if the remanence was acquired in situ or before the proposed folding. Precision parameters k before and after application of the tectonic corrections are 25.38 and 31.43, respectively. This indicates that the Sierra de Aguachile indeed was folded after emplacement of the ignimbrites, which restricts the age of the corresponding tectonic event to be younger than 31.3 +/- 0.7 Ma. Due to the gentle folding though, the difference in precision parameters is not significant at the 95% probability level.

  2. SU-E-J-246: A Deformation-Field Map Based Liver 4D CBCT Reconstruction Method Using Gold Nanoparticles as Constraints

    SciTech Connect

    Harris, W; Zhang, Y; Ren, L; Yin, F

    2014-06-01

    Purpose: To investigate the feasibility of using nanoparticle markers to validate liver tumor motion together with a deformation field map-based four dimensional (4D) cone-beam computed tomography (CBCT) reconstruction method. Methods: A technique for lung 4D-CBCT reconstruction has been previously developed using a deformation field map (DFM)-based strategy. In this method, each phase of the 4D-CBCT is considered as a deformation of a prior CT volume. The DFM is solved by a motion modeling and free-form deformation (MM-FD) technique, using a data fidelity constraint and the deformation energy minimization. For liver imaging, there is low contrast of a liver tumor in on-board projections. A validation of liver tumor motion using implanted gold nanoparticles, along with the MM-FD deformation technique is implemented to reconstruct onboard 4D CBCT liver radiotherapy images. These nanoparticles were placed around the liver tumor to reflect the tumor positions in both CT simulation and on-board image acquisition. When reconstructing each phase of the 4D-CBCT, the migrations of the gold nanoparticles act as a constraint to regularize the deformation field, along with the data fidelity and the energy minimization constraints. In this study, multiple tumor diameters and positions were simulated within the liver for on-board 4D-CBCT imaging. The on-board 4D-CBCT reconstructed by the proposed method was compared with the “ground truth” image. Results: The preliminary data, which uses reconstruction for lung radiotherapy suggests that the advanced reconstruction algorithm including the gold nanoparticle constraint will Resultin volume percentage differences (VPD) between lesions in reconstructed images by MM-FD and “ground truth” on-board images of 11.5% (± 9.4%) and a center of mass shift of 1.3 mm (± 1.3 mm) for liver radiotherapy. Conclusion: The advanced MM-FD technique enforcing the additional constraints from gold nanoparticles, results in improved accuracy

  3. DDTs in rice frogs (Rana limnocharis) from an agricultural site, South China: tissue distribution, biomagnification, and potential toxic effects assessment.

    PubMed

    Wu, Jiang-Ping; Zhang, Ying; Luo, Xiao-Jun; Chen, She-Jun; Mai, Bi-Xian

    2012-04-01

    Contamination with agricultural pesticides such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, dichlorodiphenyldichloroethylene (DDE) and dichlorodiphenyldichloroethane (DDD), is among several proposed stressors contributing to the global declines in amphibian populations and species biodiversity. These chemicals were examined in insects and in the muscle, liver, and eggs of rice frogs (Rana limnocharis) from the paddy fields of an agricultural site in South China. The ΣDDT (sum of DDT, DDE, and DDD) concentrations ranged from 154 to 915, 195 to 1,400, and 165 to 1,930 ng/g lipid weight in the muscle, liver, and eggs, respectively. All the DDTs (DDT, DDE, and DDD) showed higher affinity for the liver relative to muscle tissue and can be maternally transferred to eggs in female frogs. The average biomagnification factors for DDTs ranged from 1.6 to 1.9 and 1.5 to 2.9 in female and male frogs, respectively, providing clear evidence of their biomagnification from insects to frogs. Compared with the reported DDT levels demonstrated to have toxic effects on frogs, DDTs in the present frogs are unlikely to constitute an immediate health risk. However, the adverse impacts of high DDT residues in eggs on the hatching success and their potential toxicity to the newly metamorphosed larval frogs should be assessed further.

  4. Investigating the Origin of Natural and Anthropogenic Deformation across the Nile Delta Using Radar Interferometry, GRACE, Modeling, and Field data

    NASA Astrophysics Data System (ADS)

    Gebremichael, E.; Sultan, M.; Becker, R.; El Bastawesy, M.; Cherif, O.; Emil, M.; Ahmed, M.; Fathy, K.; Karki, S.; Chouinard, K.

    2016-12-01

    We applied an integrated approach (radar interferometry, flood simulation, GRACE, GIS) to investigate the nature and distribution of land deformation in the Nile Delta and to identify the natural and anthropogenic controlling factors. Our methodology involved: (1) applying persistent scatterer interferometry (PSI) across the entire Delta (scenes: 108 level 0 scenes; Tracks: 4 tracks; time period: 2003-2010); (2) correcting the interferometry output for various phase contributing errors (e.g., atmosphere, orbit, etc.) and calibrating/validating the output against 3 GNSS GPS stations (2 in Alexandria, 1 in Helwan); (3) conducting spatial correlation (in a GIS environment) of the radar outputs with relevant remote sensing, subsurface, and geologic datasets; (4) simulating flood depth and inundation to investigate the spatial extent and depth of the Holocene sediments using the HEC-RAS software (inputs: DEM and monthly discharge data; period: 1871-1902), (5) identifying subsurface structures by processing 712 gridded field gravity data points in Geosoft Oasis Montaj software (Bouguer anomaly analysis), and (6) analyzing monthly (2002-2015) GRACE-derived TWS solutions (0.5° x 0.5° CSR mascons). Our findings include: (1) three main structural trends (E-W, NW-SE and NE-SW trending) were mapped across the Delta, (2) areas of high subsidence coincide with the distribution of relatively thick recent sediments (<3000 years), probably due to sediment compaction, in three settings: (a) areas susceptible to flooding from the Damietta and Rosetta branches (e.g., east Damietta branch; latitude 30.8° to 31.2°; longitude 31.2° to 31.6°), (b) areas susceptible to sediment deposition at bifurcation locations of primary channels (e.g., near Cairo) and, (c) areas where mapped faults intersect Damietta and Rosetta channels, change their course, and cause ponding of surface water and sediment deposition, (3) extraction of gas from the Abu Madi gas field in north central delta

  5. Association of Myopic Deformation of Optic Disc with Visual Field Progression in Paired Eyes with Open-Angle Glaucoma

    PubMed Central

    Hangai, Masanori; Ishikawa, Makoto; Yoshitomi, Takeshi

    2017-01-01

    Purpose The influence of myopia on glaucoma progression remains unknown, possibly because of the multifactorial nature of glaucoma and difficulty in assessing a solo contribution of myopia. The purpose of this study is to investigate the association of myopia with visual field (VF) progression in glaucoma using a paired-eye design to minimize the influence of confounding systemic factors that are diverse among individuals. Methods This retrospective study evaluated 144 eyes of 72 subjects with open-angle glaucoma, with similar intra-ocular pressure between paired eyes, spherical equivalent (SE) ≤ -2 diopter (D), and axial length ≥ 24 mm. Paired eyes with faster and slower VF progression were grouped separately, according to the global VF progression rate assessed by automated pointwise linear regression analysis. The SE, axial length, tilt ratio and torsion angle of optic discs, Bruch’s membrane (BM) opening area, and gamma zone parapapillary atrophy (PPA) width were compared between the two groups. Factors associated with faster VF progression were determined by logistic regression analysis. Results The mean follow-up duration was 8.9 ± 4.4 years. The mean value of SE and axial length were -6.31 ± 1.88 D and 26.05 ± 1.12 mm, respectively. The mean global visual field progression rate was -0.32 ± 0.38 dB/y. Tilt ratio, BM opening area, and gamma zone PPA width were significantly greater in the eyes with faster VF progression than those with slower progression. In multivariate analysis, these factors were significantly associated with faster VF progression (all P < 0.05), while SE and axial length were not associated with it. Conclusion In myopic glaucoma subjects, tilt of the optic disc and temporal shifting and enlargement of the BM opening were associated with faster rate of VF progression between paired eyes. This suggests that myopia influences VF progression in glaucomatous eyes via optic disc deformations rather than via refractive error itself

  6. Development and Clinical Evaluation of a Three-Dimensional Cone-Beam Computed Tomography Estimation Method Using a Deformation Field Map

    SciTech Connect

    Ren, Lei; Chetty, Indrin J.; Zhang Junan; Jin Jianyue; Wu, Q. Jackie; Yan Hui; Brizel, David M.; Lee, W. Robert; Movsas, Benjamin; Yin Fangfang

    2012-04-01

    Purpose: To develop a three-dimensional (3D) cone-beam computed tomography (CBCT) estimation method using a deformation field map, and to evaluate and optimize the efficiency and accuracy of the method for use in the clinical setting. Methods and Materials: We propose a method to estimate patient CBCT images using prior information and a deformation model. Patients' previous CBCT data are used as the prior information, and the new CBCT volume to be estimated is considered as a deformation of the prior image volume. The deformation field map is solved by minimizing deformation energy and maintaining new projection data fidelity using a nonlinear conjugate gradient method. This method was implemented in 3D form using hardware acceleration and multi-resolution scheme, and it was evaluated for different scan angles, projection numbers, and scan directions using liver, lung, and prostate cancer patient data. The accuracy of the estimation was evaluated by comparing the organ volume difference and the similarity between estimated CBCT and the CBCT reconstructed from fully sampled projections. Results: Results showed that scan direction and number of projections do not have significant effects on the CBCT estimation accuracy. The total scan angle is the dominant factor affecting the accuracy of the CBCT estimation algorithm. Larger scan angles yield better estimation accuracy than smaller scan angles. Lung cancer patient data showed that the estimation error of the 3D lung tumor volume was reduced from 13.3% to 4.3% when the scan angle was increased from 60 Degree-Sign to 360 Degree-Sign using 57 projections. Conclusions: The proposed estimation method is applicable for 3D DTS, 3D CBCT, four-dimensional CBCT, and four-dimensional DTS image estimation. This method has the potential for significantly reducing the imaging dose and improving the image quality by removing the organ distortion artifacts and streak artifacts shown in images reconstructed by the conventional

  7. Legacy of road salt: Apparent positive larval effects counteracted by negative postmetamorphic effects in wood frogs.

    PubMed

    Dananay, Kacey L; Krynak, Katherine L; Krynak, Timothy J; Benard, Michael F

    2015-10-01

    Road salt runoff has potentially large effects on wetland communities, but is typically investigated in short-term laboratory trials. The authors investigated effects of road salt contamination on wood frogs (Rana sylvatica) by combining a field survey with 2 separate experiments. The field survey tested whether wood frog larval traits were associated with road salt contamination in natural wetlands. As conductivity increased, wood frog larvae were less abundant, but those found were larger. In the first experiment of the present study, the authors raised larvae in outdoor artificial ponds under 4 salt concentrations and measured larval vital rates, algal biomass, and zooplankton abundance. Salt significantly increased larval growth, algal biomass, and decreased zooplankton abundance. In the second experiment, the authors raised larvae to metamorphosis in the presence and absence of salt contamination and followed resulting juvenile frogs in terrestrial pens at high and low densities. Exposure to road salt as larvae caused juvenile frogs to have greater mortality in low-density terrestrial environments, possibly because of altered energy allocation, changes in behavior, or reduced immune defenses. The present study suggests that low concentrations of road salt can have positive effects on larval growth yet negative effects on juvenile survival. These results emphasize the importance of testing for effects of contaminants acting through food webs and across multiple life stages as well as the potential for population-level consequences in natural environments.

  8. Eleutherodactylus frog introductions to Hawaii

    USGS Publications Warehouse

    Kraus, Fred; Campbell, Earl W.; Allison, Allen; Pratt, Thane K.

    1999-01-01

    As an oceanic archipelago isolated from continental source areas, Hawaii lacks native terrestrial reptiles and amphibians, Polynesians apparently introduced seven gecko and skink species after discovering the islands approximately 1500 years ago, and another 15 reptiles and five frogs have been introduced in the last century and a half (McKeown 1996). The Polynesian introductions are probably inadvertent because the species involved are known stowaway dispersers (Gibbons 1985; Dye and Steadman 1990), In contrast, most of the herpetological introductions since European contact with Hawaii have been intentional. Several frog species were released for biocontrol of insects (e.g., Dendrobates auratus, Bufo marinus, Rana rugosa, Bryan 1932; Oliver and Shaw 1953), and most of the remaining species are released or escaped pets (e.g., Phelsuma spp., Chamaeleo jacksonii, Iguana iguana, McKeown 1996), Government-approved releases have not occurred for many years, but the rate of establishment of new species has increased in the past few decades because of the importation and subsequent release of pets.

  9. Mechanics of the frog ear

    PubMed Central

    van Dijk, Pim; Mason, Matthew J.; Schoffelen, Richard L. M.; Narins, Peter M.; Meenderink, Sebastiaan W. F.

    2010-01-01

    The frog inner ear contains three regions that are sensitive to airborne sound and which are functionally distinct. (1) The responses of nerve fibres innervating the low-frequency, rostral part of the amphibian papilla (AP) are complex. Electrical tuning of hair cells presumably contributes to the frequency selectivity of these responses. (2) The caudal part of the AP covers the mid-frequency portion of the frog's auditory range. It shares the ability to generate both evoked and spontaneous otoacoustic emissions with the mammalian cochlea and other vertebrate ears. (3) The basilar papilla functions mainly as a single auditory filter. Its simple anatomy and function provide a model system for testing hypotheses concerning emission generation. Group delays of stimulus frequency otoacoustic emissions (SFOAEs) from the basilar papilla are accounted for by assuming that they result from forward and reverse transmission through the middle ear, a mechanical delay due to tectorial membrane filtering and a rapid forward and reverse propagation through the inner ear fluids, with negligible delay. PMID:20149854

  10. FROGS (Friends of Granite) Report Winter 1989

    NASA Astrophysics Data System (ADS)

    The purpose of FROGS reports is to disseminate information and stimulate thinking about felsic magmatism granitoids in particular. We publish semiannually, as part of VGP News, brief updates from investigators whose current research concerns felsic magmatism, information about events and publications that are relevant to granitoids, and commentaries on new and controversial themes. FROGS Reports is critically dependent on response from people interested in these topics. Please keep me (Calvin Miller, 6028B, Vanderbilt University, Nashville, TN 37235) informed about upcoming or recent conferences, major publications, and your own research. Also, please send me your suggestions for topics for pertinent commentaries for FROGS reports (or volunteer to write one yourself!).

  11. κ-deformed oscillators: Deformed multiplication versus deformed flip operator and multiparticle clusters

    NASA Astrophysics Data System (ADS)

    Lukierski, J.

    2009-08-01

    We transform the oscillator algebra with κ-deformed multiplication rule, proposed in [1, 2], into the oscillator algebra with κ-deformed flip operator and standard multiplication. We recall that the κ-multiplication of the κ-oscillators puts them off-shell. We study the explicit forms of modified mass-shell conditions in both formulations: with κ-multiplication and with κ-flip operation. On the example of κ-deformed 2-particle states we study the clustered nonfactorizable form of the κ-deformed multiparticle states. We argue that the κ-deformed star product of two free fields leads in similar way to a nonfactorizable κ-deformed bilocal field. We conclude with general remarks concerning the κ-deformed n-particle clusters and κ-deformed star product of n fields.

  12. Coseismic and post-seismic deformation fields mapped using satellite radar interferometry and fault slip inversion of the 2015 Mw8.3 Illapel earthquake, Chile

    NASA Astrophysics Data System (ADS)

    Chunyan, Qu; Ronghu, Zuo; XinJian, Shan; Guohong, Zhang; Yingfeng, Zhang; Xiaogang, Song; Yunhua, Liu; Guifang, Zhang

    2017-02-01

    We analyzed Sentinel-1A (S1A)/IW satellite descending data from multiple acquisitions to map coseismic and post-seismic deformation fields and invert the fault slip and afterslip models associated with the seismic moment magnitude (Mw)8.3 earthquake that occurred at Illapel, Chile, on September 16th, 2015. We generated one coseismic and four post-seismic interferograms to analyze temporal and spatial variations in the deformation field after the mainshock; we found that the coseismic deformation field has a semicircular shape and covers a 300-km long and 190-km wide area. The maximum displacement reaches ca. 1.33 m in the LOS subsidence direction, while post-seismic deformation derived from four interferograms with different time intervals is mainly distributed within a long narrow area approximately 65 km wide. Maximum displacement is ca. 8 cm, including two regions of line of sight (LOS) uplift and sinking. Major regions of deformation exhibit opposite directions to the mainshock just after the event, before reverting to consistency. We inverted the coseismic fault slip and afterslip models based on a shallow-dip single fault plane in a homogeneous elastic half space. Our inversion suggests that coseismic slip is mainly concentrated in a shallow region to the northwest of the source, and that rupture length along strike is close to 340 km, with a maximum slip of about 8.16 m to the trench. The estimated moment is 3.126 × 1021 N m (Mw8.27), and the maximum rupture depth is 50 km. Inverted residual slip also shows just one region of slip in the shallow subsurface, which is shifted slightly to the south. In the early stage of deformation, the residual is along the down-dip direction, with a maximum value of ca. 32 cm, before turning into the up-dip direction, with a maximum value of ca. 23 cm. Finally, we present a preliminary analysis of these complex changes in space and time.

  13. California Red-legged Frog - Stipulated Injunction

    EPA Pesticide Factsheets

    EPA will make effects determinations and initiate consultation with the U.S. Fish and Wildlife Service, regarding the potential effects of 66 pesticide active ingredient registrations on the California red-legged frog.

  14. Meeting the "Standards" with Vanishing Frogs.

    ERIC Educational Resources Information Center

    Davidson, Cindy B.; Matthews, Catherine E.; Patrick, Patricia

    2001-01-01

    Explains methods for introducing high school students to the issue of the declining amphibian population. Plays the game Frogs' Futures following a seminar as an instructional strategy. Describes the game, procedures, and rules. (YDS)

  15. Meeting the "Standards" with Vanishing Frogs.

    ERIC Educational Resources Information Center

    Davidson, Cindy B.; Matthews, Catherine E.; Patrick, Patricia

    2001-01-01

    Explains methods for introducing high school students to the issue of the declining amphibian population. Plays the game Frogs' Futures following a seminar as an instructional strategy. Describes the game, procedures, and rules. (YDS)

  16. FROGS Report Friends of Granite Summer 1989

    NASA Astrophysics Data System (ADS)

    FROGS Reports present information on current research relevant to felsic magmatism, including commentaries on problems of current interest. Please contact Calvin Miller (6028B, Vanderbilt University, Nashville, TN 37235) concerning your own research, conferences, and ideas for stimulating commentaries.

  17. Internal fertilization in an oviparous frog.

    PubMed

    Townsend, D S; Stewart, M M; Pough, F H; Brussard, P F

    1981-04-24

    Eleutherodactylus coqui, an oviparous frog, undergoes internal fertilization. If this mode of fertilization occurs in other species of anurans, interpretations of anuran reproductive strategies based on the assumption of external fertilization must be reviewed.

  18. Longitudinal Analysis of Image Time Series with Diffeomorphic Deformations: A Computational Framework Based on Stationary Velocity Fields

    PubMed Central

    Hadj-Hamou, Mehdi; Lorenzi, Marco; Ayache, Nicholas; Pennec, Xavier

    2016-01-01

    We propose and detail a deformation-based morphometry computational framework, called Longitudinal Log-Demons Framework (LLDF), to estimate the longitudinal brain deformations from image data series, transport them in a common space and perform statistical group-wise analyses. It is based on freely available software and tools, and consists of three main steps: (i) Pre-processing, (ii) Position correction, and (iii) Non-linear deformation analysis. It is based on the LCC log-Demons non-linear symmetric diffeomorphic registration algorithm with an additional modulation of the similarity term using a confidence mask to increase the robustness with respect to brain boundary intensity artifacts. The pipeline is exemplified on the longitudinal Open Access Series of Imaging Studies (OASIS) database and all the parameters values are given so that the study can be reproduced. We investigate the group-wise differences between the patients with Alzheimer's disease and the healthy control group, and show that the proposed pipeline increases the sensitivity with no decrease in the specificity of the statistical study done on the longitudinal deformations. PMID:27375408

  19. Longitudinal Analysis of Image Time Series with Diffeomorphic Deformations: A Computational Framework Based on Stationary Velocity Fields.

    PubMed

    Hadj-Hamou, Mehdi; Lorenzi, Marco; Ayache, Nicholas; Pennec, Xavier

    2016-01-01

    We propose and detail a deformation-based morphometry computational framework, called Longitudinal Log-Demons Framework (LLDF), to estimate the longitudinal brain deformations from image data series, transport them in a common space and perform statistical group-wise analyses. It is based on freely available software and tools, and consists of three main steps: (i) Pre-processing, (ii) Position correction, and (iii) Non-linear deformation analysis. It is based on the LCC log-Demons non-linear symmetric diffeomorphic registration algorithm with an additional modulation of the similarity term using a confidence mask to increase the robustness with respect to brain boundary intensity artifacts. The pipeline is exemplified on the longitudinal Open Access Series of Imaging Studies (OASIS) database and all the parameters values are given so that the study can be reproduced. We investigate the group-wise differences between the patients with Alzheimer's disease and the healthy control group, and show that the proposed pipeline increases the sensitivity with no decrease in the specificity of the statistical study done on the longitudinal deformations.

  20. Modeling the (Sub)surface Deformation Field Evolution Due to Production from a Hydrocarbon Reservoir Overlain by Rocksalt

    NASA Astrophysics Data System (ADS)

    Marketos, G.; Govers, R. M. A.; Spiers, C. J.

    2014-12-01

    Rocksalt is an important caprock for sealing or trapping hydrocarbons. Given its relatively low viscosity, it may flow during and after production and result in time-dependent surface deformation. To predict the consequences of alternative production strategies, we seek to understand the primary controls on stress-driven flow and surface deformation of hydrocarbon extraction from a reservoir topped by rocksalt. The mechanical properties of rock salt are a key influence, but complicated. Depending on grain size, temperature, and stress, salt can deform mainly elastically, by power law viscous creep, and/or by linear viscous diffusion creep. In this study, we evaluate the evolution of production induced deformation using generic geo-mechanical models. Our strategy is to start with simplified geometries, rheologies, and forcing, and to increase model complexity slowly. Our results show that there are two distinctly different time scales that dominate the evolution of the models: short term subsidence and longer term partial rebound. The shortest time scale corresponds to stress-driven flow in the vicinity of the reservoir. The longest time scale is controlled by resistance to viscous flow and stress relaxation within a wider region of the rocksalt layer. We discuss the sensitivity to the thickness of the rocksalt seal, the geometry of the reservoir, and the distance between the source and the seal.

  1. New structural field data on the timing and kinematics of deformation and exhumation of the Mont Blanc massif

    NASA Astrophysics Data System (ADS)

    Egli, Daniel; Mancktelow, Neil

    2010-05-01

    thrust around 2.5 Ma, based on exhumation rates established from fission track ages. However, no sign of young movements along the boundary/back-thrust between the Mont Blanc basement and the overlying sediments has been found during our structural study. The actual contact between the basement and cover cannot be a very late stage structure because it is slightly folded with a new steep fabric developed in both the sediments and the granite. This result is in good accordance with the data of Glotzbach et al. (2008), which show no offset in FT-ages across the Mont Blanc back-thrust along their tunnel transect. Strike-slip movements can be observed in the whole field area. The main direction is oriented SW-NE with right-lateral deformation both in the ductile and in the brittle field. This suggests a continuous dextral movement and would support the flower-structure theory. However, the most recent uplift of the Mont Blanc relative to its cover seems to be widely distributed and not restricted to discrete structures, since no major exhumation-related structures have been found. Currently, the question still remains open whether tectonics or surface processes play the dominant role in controlling this differential uplift. References: Glotzbach, C., Reinecker J., Danisik, M., Rahn, M., Frisch, W. & Spiegel, C., 2008: Neogene exhumation history of the Mont Blanc massif, western Alps, Tectonics, 27. Leloup, P. H., Arnaud, N., Sobel, E. R. & Lacassin, R., 2005: Alpine thermal and structural evolution of the highest external crystalline massif: The Mont Blanc, Tectonics, 24. Von Raumer, J.F., Ménot, R.P., Abrecht, J. & Biino, G., 1993: The Pre-Alpine evolution of the External Massifs. In: J.F. von Raumer and F. Neubauer (Eds.), Pre-Mesozoic geology in the Alps. Springer Verlag, Berlin Heidelberg, 221-240. Rolland, Y., Corsini M., Rossi, M., Cox, S. F., Pennacchioni, G., Mancktelow, N. & Boullier, A. M., 2007: Comment on "Alpine thermal and structural evolution of the highest

  2. Analyzing axial stress and deformation of tubular for steam injection process in deviated wells based on the varied (T, P) fields.

    PubMed

    Liu, Yunqiang; Xu, Jiuping; Wang, Shize; Qi, Bin

    2013-01-01

    The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells.

  3. Analyzing Axial Stress and Deformation of Tubular for Steam Injection Process in Deviated Wells Based on the Varied (T, P) Fields

    PubMed Central

    Liu, Yunqiang; Xu, Jiuping; Wang, Shize; Qi, Bin

    2013-01-01

    The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells. PMID:24163623

  4. Factors influencing survival and mark retention in postmetamorphic boreal chorus frogs

    USGS Publications Warehouse

    Swanson, Jennifer E; Bailey, Larissa L.; Muths, Erin L.; Funk, W. Chris

    2013-01-01

    The ability to track individual animals is crucial in many field studies and often requires applying marks to captured individuals. Toe clipping has historically been a standard marking method for wild amphibian populations, but more recent marking methods include visual implant elastomer and photo identification. Unfortunately, few studies have investigated the influence and effectiveness of marking methods for recently metamorphosed individuals and as a result little is known about this life-history phase for most amphibians. Our focus was to explore survival probabilities, mark retention, and mark migration in postmetamorphic Boreal Chorus Frogs (Psuedacris maculata) in a laboratory setting. One hundred forty-seven individuals were assigned randomly to two treatment groups or a control group. Frogs in the first treatment group were marked with visual implant elastomer, while frogs in the second treatment group were toe clipped. Growth and mortality were recorded for one year and resulting data were analyzed using known-fate models in Program MARK. Model selection results suggested that survival probabilities of frogs varied with time and showed some variation among marking treatments. We found that frogs with multiple toes clipped on the same foot had lower survival probabilities than individuals in other treatments, but individuals can be marked by clipping a single toe on two different feet without any mark loss or negative survival effects. Individuals treated with visual implant elastomer had a mark migration rate of 4% and mark loss rate of 6%, and also showed very little negative survival impacts relative to control individuals.

  5. DNA repair and resistance to UV-B radiation in western spotted frogs

    USGS Publications Warehouse

    Blaustein, A.R.; Hays, J.B.; Hoffman, P.D.; Chivers, D.P.; Kiesecker, J.M.; Leonard, W.P.; Marco, A.; Olson, D.H.; Reaser, J.K.; Anthony, R.G.

    1999-01-01

    We assessed DNA repair and resistance to solar radiation in eggs of members of the western spotted frog complex (Rana pretiosa and R. luteiventris), species whose populations are suffering severe range reductions and declines. Specifically, we measured the activity of photoreactivating enzyme (photolyase) in oocytes of spotted frogs. In some species, photoreactivation is the most important mechanism for repair of UV-damaged DNA. Using field experiments, we also compared the hatching success of spotted frog embryos at natural oviposition sites at three elevations, where some embryos were subjected to ambient levels of UV-B radiation and others were shielded from UV-B radiation. Compared with other amphibians, photolyase activities in spotted frogs were relatively high. At all sites, hatching success was unaffected by UV-B. Our data support the interpretation that amphibian embryos with relatively high levels of photolyase are more resistant to UV-B radiation than those with lower levels of photolyase. At the embryonic stage, UV-B radiation does not presently seem to be contributing to the population declines of spotted frogs.

  6. The Effects of Alkali Metal Cations and Common Anions on the Frog Skin Potential

    PubMed Central

    Lindley, Barry D.; Hoshiko, T.

    1964-01-01

    The effects on the potential difference across isolated frog skin (R. catesbeiana, R. pipiens) of changing the ionic composition of the bathing solutions have been examined. Estimates of mean values and precision are presented for the potential changes produced by substituting other alkali metal cations for Na at the outside border and for K at the inside border. In terms of ability to mimic Na at the outside border of bullfrog skin, the selectivity order is Li > Rb, K, Cs; at the outside border of leopard frog skin, Li > Cs, K, Rb. In terms of ability to mimic K at the inside border of bullfrog and leopard frog skin: Rb > Cs > Li > Na. Orders of anion selectivity in terms of sensitivity of the potential for the outside border of bullfrog skin are Br > Cl > NO3 > I > SO4, isethionate and of leopard frog skin are Br, Cl > I, NO3, SO4. An effect of the solution composition (ionic strength?) on the apparent Na-K selectivity of the outside border is described. The results of the investigation have been interpreted and discussed in terms of the application of the constant field equation to the Koefoed-Johnsen-Ussing frog skin model. These observations may be useful in constructing and testing models of biological ionic selectivity. PMID:14127610

  7. LITTLE FROG ROADLESS AREA, TENNESSEE.

    USGS Publications Warehouse

    Force, Eric R.; Gazdik, Gertrude C.

    1984-01-01

    No mineral-resource potential was identified during studies of the Little Frog Roadless Area, Tennessee. Possibilities exist, however, for the occurrence of massive sulfide-bearing rocks of the type mined in the adjacent Ducktown Basin at depth beneath the roadless area. A possibility also exists for the presence of natural gas in sedimentary rocks at great depth. Insufficient data to support these concepts precludes assessing any of the roadless area as having resource potential. A limited amount of geologic mapping coupled with seismic work would be useful to test whether rocks of the Ducktown Basin are present at depth under the roadless areas. Seismic work and drilling would be necessary also to test for the presence of gas at great depths.

  8. Development of the pseudothumb in frogs

    PubMed Central

    Tokita, Masayoshi; Iwai, Noriko

    2010-01-01

    Frogs have highly conserved hand and foot morphology, possessing four fingers and five toes. As an exception, two Japanese ranid frog species, the Otton frog Babina subaspera and the dagger frog Babina holsti, possess a unique thumb-like structure (the pseudothumb) in the forelimb, giving an appearance of a total of five fingers on the hand. To obtain insights into the developmental mechanisms that generate this novel character, we investigated the hand morphogenesis of the Otton frog. The unique morphological pattern of the pseudothumb was already established in juveniles. Surprisingly, the bud-like structure, which is similar to the area of inductive activity (e.g. feather buds in birds and the carapacial ridge in turtles), was detected over the site where the future prepollex develops in larvae. By contrast, this bud-like structure was not found in larvae of other ranid species. We discuss possible scenarios that would favour the evolution of this very unusual trait in frogs. PMID:20147308

  9. Sound Generating Mechanism of Frog Shaped Guiros

    NASA Astrophysics Data System (ADS)

    Iwatsuki, Nobuyuki; Morikawa, Koichi

    A frog shaped guiro is a wooden percussion instrument with an open-ended cave. By rubbing dorsal fins like saw blades on a back of the guiro with a wooden stick, the guiro generates the sound like a frog's voice. The exciting force, response acceleration and radiating sound pressure were measured with accelerometers on the stick and guiro and a condenser microphone and then the relation between the impulsively exciting force and sound pressure was revealed. A three-dimensional solid model of the guiro was built by use of an X-ray CT scanner device and a finite element model composed of tetrahedral elements was then obtained. The FEM modal analysis revealed that the frog shaped guiro had four dominant modes of vibration which was characterized by motion of mouth of the guiro such as the yawn mode and grinding teeth mode. The frequency spectrum of the sound pressure radiating from the frog shaped guiro excited by sequential impulsive forces moving along the dorsal fins was theoretically estimated. Since the estimated sound pressure agreed well with the measured one, the sound radiating from the guiro like a frog's voice could be reproduced. It was also revealed that the variation of driving point mobility of the dorsal fins and amplitude of the exciting force affected to generate the sound like a frog's voice.

  10. Tolerance of fungal infection in European water frogs exposed to Batrachochytrium dendrobatidis after experimental reduction of innate immune defenses.

    PubMed

    Woodhams, Douglas C; Bigler, Laurent; Marschang, Rachel

    2012-10-23

    While emerging diseases are affecting many populations of amphibians, some populations are resistant. Determining the relative contributions of factors influencing disease resistance is critical for effective conservation management. Innate immune defenses in amphibian skin are vital host factors against a number of emerging pathogens such as ranaviruses and the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Adult water frogs from Switzerland (Pelophylax esculentus and P. lessonae) collected in the field with their natural microbiota intact were exposed to Bd after experimental reduction of microbiota, skin peptides, both, or neither to determine the relative contributions of these defenses. Naturally-acquired Bd infections were detected in 10/51 P. lessonae and 4/19 P. esculentus, but no disease outbreaks or population declines have been detected at this site. Thus, this population was immunologically primed, and disease resistant. No mortality occurred during the 64 day experiment. Forty percent of initially uninfected frogs became sub-clinically infected upon experimental exposure to Bd. Reduction of both skin peptide and microbiota immune defenses caused frogs to gain less mass when exposed to Bd than frogs in other treatments. Microbiota-reduced frogs increased peptide production upon Bd infection. Ranavirus was undetectable in all but two frogs that appeared healthy in the field, but died within a week under laboratory conditions. Virus was detectable in both toe-clips and internal organs. Intact skin microbiota reduced immune activation and can minimize subclinical costs of infection. Tolerance of Bd or ranavirus infection may differ with ecological conditions.

  11. Madelung Deformity.

    PubMed

    Kozin, Scott H; Zlotolow, Dan A

    2015-10-01

    Madelung deformity of the wrist is more common in females and is often associated with Leri Weill dyschondrosteosis, a mesomelic form of dwarfism. Patients with Madelung deformity often report wrist deformity resulting from the prominence of the relatively long ulna. The typical Madelung deformity is associated with a Vickers ligament that creates a tether across the volar-ulnar radial physis that restricts growth across this segment. The distal radius deforms in the coronal (increasing radial inclination) and the sagittal (increasing volar tilt) planes. There is lunate subsidence and the proximal carpal row adapts to the deformity by forming an upside-down pyramid shape or triangle. Treatment depends on the age at presentation, degree of deformity, and magnitude of symptoms. Mild asymptomatic deformity warrants a period of nonsurgical management with serial x-ray examinations because the natural history is unpredictable. Many patients never require surgical intervention. Progressive deformity in the young child with considerable growth potential remaining requires release of Vickers ligament and radial physiolysis to prevent ongoing deterioration Concomitant ulnar epiphysiodesis may be necessary. Advanced asymptomatic deformity in older children with an unacceptable-appearing wrist or symptomatic deformity are indications for surgery. A dome osteotomy of the radius allows 3-dimensional correction of the deformity. Positive radiographic and clinical results after dome osteotomy have been reported. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  12. From Virtual Frog to Frog Island: Design Studies in a Development Project.

    ERIC Educational Resources Information Center

    Dev, Parvati; Walker, Decker F.

    1999-01-01

    Explores the efforts of a curriculum development team who set out to create a virtual frog for use in biology education, but instead, after several design studies, developed a virtual world called Frog Island. Argues for incorporating educational design studies into other educational development projects. (CMK)

  13. Tactical reproductive parasitism via larval cannibalism in Peruvian poison frogs

    PubMed Central

    Brown, Jason L.; Morales, Victor; Summers, Kyle

    2008-01-01

    We report an unusual example of reproductive parasitism in amphibians. Dendrobates variabilis, an Amazonian poison frog, oviposits at the surface of the water in small pools in plants and deposits tadpoles within the pools. Tadpoles are highly cannibalistic and consume young tadpoles if they are accessible. Deposition of embryos and tadpoles in the same pool is common. Genetic analyses indicate that tadpoles are frequently unrelated to embryos in the same pool. A pool choice experiment in the field demonstrated that males carrying tadpoles prefer to place them in pools with embryos, facilitating reproductive parasitism via cannibalism. PMID:19042178

  14. Expression analysis and identification of antimicrobial peptide transcripts from six North American frog species

    USGS Publications Warehouse

    Robertson, Laura S.; Fellers, Gary M.; Marranca, Jamie Marie; Kleeman, Patrick M.

    2013-01-01

    Frogs secrete antimicrobial peptides onto their skin. We describe an assay to preserve and analyze antimicrobial peptide transcripts from field-collected skin secretions that will complement existing methods for peptide analysis. We collected skin secretions from 4 North American species in the field in California and 2 species in the laboratory. Most frogs appeared healthy after release; however, Rana boylii in the Sierra Nevada foothills, but not the Coast Range, showed signs of morbidity and 2 died after handling. The amount of total RNA extracted from skin secretions was higher in R. boylii and R. sierrae compared to R. draytonii, and much higher compared to Pseudacris regilla. Interspecies variation in amount of RNA extracted was not explained by size, but for P. regilla it depended upon collection site and date. RNA extracted from skin secretions from frogs handled with bare hands had poor quality compared to frogs handled with gloves or plastic bags. Thirty-four putative antimicrobial peptide precursor transcripts were identified. This study demonstrates that RNA extracted from skin secretions collected in the field is of high quality suitable for use in sequencing or quantitative PCR (qPCR). However, some species do not secrete profusely, resulting in very little extracted RNA. The ability to measure transcript abundance of antimicrobial peptides in field-collected skin secretions complements proteomic analyses and may provide insight into transcriptional mechanisms that could affect peptide abundance.

  15. Colonization and biology of the frog-feeding mosquito Uranotaeinia macfarlanei in the Ryukyu Archipelago.

    PubMed

    Miyagi, Ichiro; Toma, Takako; Tamashiro, Mikako; Higa, Yukiko; Kinjyo, Takako; Takara, Tomio

    2010-03-01

    A colony of Uranotaenia macfarlanei, a frog-feeding mosquito, was established in the laboratory. We report the bionomics of the species, as studied in the laboratory colony and in the field on Ryukyu Island, Japan. These include mating activity, feeding and resting habits, manner of oviposition, and egg, larval, and pupal periods.

  16. A simulation study of planar swaging deformation

    NASA Astrophysics Data System (ADS)

    Zhang, Cheng-Gen; Jen, Gwang-Shen; Su, Gwang-Huei

    1992-08-01

    Planar swaging deformation was studied with a photoplastic method. The domestic polycarbonate was used as a simulation material. The full-field strain distribution for planar swaging deformation was obtained. The average error of the calculated strain was less than 7 percent. The deformation area and the effect of friction on deformation area were studied with the characteristics of photoplasticity. This paper points out the special features of planar swaging deformation and the effect of lubrication on deformation flow.

  17. The 1999 (Mw 7.1) Hector Mine, California, Earthquake: Near-Field Postseismic Deformation from ERS Interferometry

    NASA Technical Reports Server (NTRS)

    Jacobs, Allison; Sandwell, David; Fialko, Yuri; Sichoix, Lydie

    2002-01-01

    Interferometric synthetic aperture radar (InSAR) data over the area of the Hector Mine earthquake (Mw 7.1, 16 October 1999) reveal postseismic deformation of several centimeters over a spatial scale of 0.5 to 50 km. We analyzed seven SAR acquisitions to form interferograms over four time periods after the event. The main deformations seen in the line-of-sight (LOS) displacement maps are a region of subsidence (60 mm LOS increase) on the northern end of the fault, a region of uplift (45 mm LOS decrease) located to the northeast of the primary fault bend, and a linear trough running along the main rupture having a depth of up to 15 mm and a width of about 2 km. We correlate these features with a double left-bending, rightlateral, strike-slip fault that exhibits contraction on the restraining side and extension along the releasing side of the fault bends. The temporal variations in the near-fault postseismic deformation are consistent with a characteristic time scale of 135 + 42 or - 25 days, which is similar to the relaxation times following the 1992 Landers earthquake. High gradients in the LOS displacements occur on the fault trace, consistent with afterslip on the earthquake rupture. We derive an afterslip model by inverting the LOS data from both the ascending and descending orbits. Our model indicates that much of the afterslip occurs at depths of less than 3 to 4 km.

  18. Field Investigation of Surface Deformation Induced by the 2016 Meinong Earthquake and its Implications to Regional Geological Structures

    NASA Astrophysics Data System (ADS)

    Yi, De-Cheng; Chuang, Ray Y.; Lin, Ching-Weei

    2017-04-01

    We demonstrate mapping results of a newly-identified active folding-associated fault in southwestern Taiwan, which was triggered by the distant ML 6.6 Meinong earthquake in 2016. The 14.6-km-deep main shock occurred in Meinong at 3:57 (GMT +08) on February 6th while a series of 21-27 km deep aftershocks were induced after 160 seconds in Guanmiao, where is 25km NW away from the epicenter of the main shock. The focal mechanism of the Meinong main shock shows a westward oblique thrust with the fault plane of 275°/42°/17° (strike/dip/rake) but Guanmiao aftershocks show the N-S striking eastward normal movement. The study area locates at an on-going fold-and-thrust belt close to the deformation front of Taiwan orogeny with high rates of convergence, uplift and erosion. The geology of SW Taiwan is characterized by the 3-km-thick mudstones with high fluid pressure underlying the loose sedimentary rocks forming mud diapirs or mud-core anticlines. The significance of the Meinong earthquake is (1) aftershocks are far away from the main shock, and (2) the surface cracks partially distributed systematically along lineaments observed from InSAR, which has never been recognized as geological structures before. This study aims to establish possible kinematic processes of shallow deformation induced by the Meinong earthquake. We mapped surface cracks around the lineaments by using hand-held GPS and measured surface cracks by the compass and vernier. Among 249 kinematic data measured from 244 observed surface cracks and ruptures, the type of deformation was mostly identified as dilation or lateral translation and only 4 data were compressional deformation. The overall surface displacement moved to the northwest and west, consistent with the regional coseismic movement. The opening of the surface cracks range from 0.5 to 105 mm and 85% of them are less than 10 mm. Preseismic deformed features such as failure of the retaining wall were also observed along the western and eastern

  19. Inducing magnetic anisotropy and optimized microstructure in rapidly solidified Nd-Fe-B based magnets by thermal gradient, magnetic field and hot deformation

    NASA Astrophysics Data System (ADS)

    Zhao, L. Z.; Li, W.; Wu, X. H.; Hussain, M.; Liu, Z. W.; Zhang, G. Q.; Greneche, J. M.

    2016-10-01

    Direct preparation of Nd-Fe-B alloys by rapid solidification of copper mold casting is a very simple and low cost process for mini-magnets, but these magnets are generally magnetically isotropic. In this work, high coercivity Nd24Co20Fe41B11Al4 rods were produced by injection casting. To induce magnetic anisotropy, temperature gradient, assisted magnetic field, and hot deformation (HD) procedures were employed. As-cast samples showed non-uniform microstructure due to the melt convection. The thermal gradient during solidification led to the formation of radially distributed acicular hard magnetic grains, which gives the magnetic anisotropy. The growth of the oriented grains was confirmed by phase field simulation. A magnetic field up to 1 T applied along the casting direction could not induce significant magnetic anisotropy, but it improved the magnetic properties by reducing the non-uniformity and forming a uniform microstructure. The annealed alloys exhibited high intrinsic coercivity but disappeared anisotropy. HD was demonstrated to be a good approach for inducing magnetic anisotropy and enhanced coercivity by deforming and refining the grains. This work provides an alternative approach for preparing fully dense Nd-rich anisotropic bulk Nd-Fe-B magnets.

  20. A new GPS velocity field for the Pacific Plate - Part 1: constraints on plate motion, intraplate deformation, and the viscosity of Pacific basin asthenosphere

    NASA Astrophysics Data System (ADS)

    DeMets, C.; Márquez-Azúa, Bertha; Cabral-Cano, Enrique

    2014-12-01

    We combine new, well-determined GPS velocities from Clarion, Guadalupe and Socorro islands on young seafloor in the eastern Pacific basin with newly estimated velocities for 26 GPS sites from older seafloor in the central, western and southern parts of the Pacific Plate to test for deformation within the interior of the Pacific Plate and estimate the viscosity of the asthenosphere below the plate. Relative to a Pacific Plate reference frame defined from the velocities of the 26 GPS sites in other areas of the Pacific Plate, GPS sites on Clarion and Guadalupe islands in the eastern Pacific move 1.2 ± 0.6 mm yr-1 (1σ) towards S09°W ± 38° and 1.9 ± 0.3 mm yr-1 towards S19°E ± 10°, respectively. The two velocities, which are consistent within their 95 per cent uncertainties, both differ significantly from Pacific Plate motion. Transient volcanic deformation related to a 1993-1996 eruption of the Socorro Island shield volcano renders our GPS velocity from that island unreliable for the tectonic analysis although its motion is also southward like those of Clarion and Guadalupe islands. We test but reject the possibilities that drift of Earth's origin in ITRF2008 or unmodelled elastic offsets due to large-magnitude earthquakes around the Pacific rim since 1993 can be invoked to explain the apparent slow southward motions of Clarion and Guadalupe islands. Similarly, corrections to the Pacific Plate GPS velocity field for possible viscoelastic deformation triggered by large-magnitude earthquakes since 1950 also fail to explain the southward motions of the two islands. Viscoelastic models with prescribed asthenospheric viscosities lower than 1 × 1019 Pa s instead introduce statistically significant inconsistencies into the Pacific Plate velocity field, suggesting that the viscosity of the asthenosphere below the plate is higher than 1 × 1019 Pa s. Elastic deformation from locked Pacific-North America Plate boundary faults is also too small to explain the southward

  1. Hands-on Science. How Do Polliwogs Become Frogs?

    ERIC Educational Resources Information Center

    Kepler, Lynne

    1993-01-01

    Describes a miniscience unit on frogs for elementary grades that teaches students about how frogs develop from tadpoles and how frogs need water during their entire life cycle. Students learn such skills as observation, collecting, and recording data. Provides addresses for ordering resources for teachers and students. (SM)

  2. 49 CFR 213.141 - Self-guarded frogs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Self-guarded frogs. 213.141 Section 213.141..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.141 Self-guarded frogs. (a) The raised guard on a self-guarded frog shall not be worn more than three-eighths of an inch. (b) If repairs...

  3. 49 CFR 213.139 - Spring rail frogs.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The... wing rail shall be solidly tamped and fully and tightly bolted. (c) Each frog with a bolt hole defect...

  4. 49 CFR 213.141 - Self-guarded frogs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Self-guarded frogs. 213.141 Section 213.141..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.141 Self-guarded frogs. (a) The raised guard on a self-guarded frog shall not be worn more than three-eighths of an inch. (b) If repairs...

  5. 49 CFR 213.141 - Self-guarded frogs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Self-guarded frogs. 213.141 Section 213.141..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.141 Self-guarded frogs. (a) The raised guard on a self-guarded frog shall not be worn more than three-eighths of an inch. (b) If repairs...

  6. 49 CFR 213.139 - Spring rail frogs.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The... wing rail shall be solidly tamped and fully and tightly bolted. (c) Each frog with a bolt hole defect...

  7. 49 CFR 213.139 - Spring rail frogs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The... wing rail shall be solidly tamped and fully and tightly bolted. (c) Each frog with a bolt hole defect...

  8. 49 CFR 213.139 - Spring rail frogs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The... wing rail shall be solidly tamped and fully and tightly bolted. (c) Each frog with a bolt hole defect...

  9. 49 CFR 213.141 - Self-guarded frogs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Self-guarded frogs. 213.141 Section 213.141..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.141 Self-guarded frogs. (a) The raised guard on a self-guarded frog shall not be worn more than three-eighths of an inch. (b) If repairs...

  10. 49 CFR 213.139 - Spring rail frogs.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Spring rail frogs. 213.139 Section 213.139..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.139 Spring rail frogs. (a) The... wing rail shall be solidly tamped and fully and tightly bolted. (c) Each frog with a bolt hole defect...

  11. 49 CFR 213.141 - Self-guarded frogs.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Self-guarded frogs. 213.141 Section 213.141..., DEPARTMENT OF TRANSPORTATION TRACK SAFETY STANDARDS Track Structure § 213.141 Self-guarded frogs. (a) The raised guard on a self-guarded frog shall not be worn more than three-eighths of an inch. (b) If repairs...

  12. Hands-on Science. How Do Polliwogs Become Frogs?

    ERIC Educational Resources Information Center

    Kepler, Lynne

    1993-01-01

    Describes a miniscience unit on frogs for elementary grades that teaches students about how frogs develop from tadpoles and how frogs need water during their entire life cycle. Students learn such skills as observation, collecting, and recording data. Provides addresses for ordering resources for teachers and students. (SM)

  13. Casing deformation in Ekofisk

    SciTech Connect

    Yudovich, A. ); Chin, L.Y. ); Morgan, D.R. )

    1989-07-01

    Casing deformation resulting from reservoir compaction occurred in the Ekofisk field operated by Phillips Petroleum Co. Norway and is a serious problem in three of the fields. This study established a relationship between reservoir compaction and casing failure by statistical analyses, finite-element modeling (FEM), and the analyses of deformed casing and logs run through collapsed casings. Ekofisk casing deformation is related primarily to the near well incremental strain, well inclination, and casing diameter. Useful correlations to estimate future probabilities of casing deformation as a function of reservoir variables and well parameters were also obtained. The authors concluded that casing failure induced by reservoir compaction can be minimized through a pressure-maintenance program to reduce strain by drilling with the highest practical angle and by using the largest possible casing in the well.

  14. Magnetic Field and Slip Effects on the Flow and Heat Transfer of Stagnation Point Jeffrey Fluid over Deformable Surfaces

    NASA Astrophysics Data System (ADS)

    Turkyilmazoglu, Mustafa

    2016-06-01

    The Mhd slip flow and heat transfer of stagnation point Jeffrey fluid over deformable surfaces are the state of the art of this article. Following an analytical approach, the existence, uniqueness, and possible multiplicity of the physical solutions affected by several physical parameters are investigated. Particularly, magnetic interaction and slip factor are shown to much influence the structure of the solutions regarding both momentum and thermal boundary layers. The presented exact solutions not only provide a clear understanding of fruitful physical mechanisms present in this nonlinear flow problem but they have also merits in calculations by means of numerous numerical schemes aiming to explore further complex phenomena.

  15. Seismogenic deformation field in the Mojave block and implications for tectonics of the eastern California shear zone

    NASA Astrophysics Data System (ADS)

    Unruh, Jeffrey R.; Twiss, Robert J.; Hauksson, Egill

    1996-04-01

    From the aftershocks of the 1992 Landers earthquake, we infer the orientation of the principal strain rate axes (d1 > d2 > d3; d1 lengthening), their relative magnitude, and the relative spin of fault blocks by using a micropolar continuum model to invert the seismic P and T axes. The seismogenic deformation is consistent with the geodetic measurements of the coseismic displacement and with the secular deformation of the central Mojave block. Regionally, the aftershock data define two major domains within the central Mojave block: (1) the western Mojave block, including the San Bernardino Mountains and the epicentral area of the Big Bear earthquake, which is characterized by E-W d1 (lengthening) and N-S d3 (shortening); and (2) the central Mojave block, including the Landers surface rupture zone, which is characterized by NW-SE d1 and NE-SW d3. Inversion for the principal strain axes of geodetically measured coseismic displacements across the Big Bear and Landers seismogenic zones gives results similar to the aftershock inversions for those areas, indicating that the aftershocks accommodate a deformation similar to the main rupture and do not reflect elastic rebound or residual stresses. The background seismicity for 1981 to 1991 shows the same characteristic d1 and d3 orientations for the two domains, indicating that the secular seismogenic strain has the same regional geometry as the 1992 coseismic deformation. The micropolar inversion also provides values of the relative vorticity parameter W, which reflects a difference between the vorticity of a shearing continuum and the vorticity of fault-bounded blocks rotating within tabular seismogenic shear zones. The observed fault geometry along the Kickapoo fault suggests a pinned-block model for the local block rotation that is consistent with the values of W obtained from our inversions. We interpret the regional NW-SE orientation of d1 in the central Mojave block to be characteristic of the dextral eastern

  16. Pain perception and anaesthesia in research frogs.

    PubMed

    Guénette, Sarah Annie; Giroux, Marie-Chantal; Vachon, Pascal

    2013-01-01

    Frogs possess pain receptors and pathways that support processing and perception of noxious stimuli however the level of organization is less well structured compared to mammals. It was long believed that the experience of pain was limited to 'higher' phylums of the animal kingdom. However, it is now commonly accepted that amphibians possess neuro-anatomical pathways conductive of a complete nociceptive experience. Xenopus laevis frogs have been one of the most popular aquatic research models for developmental studies and genetic research. These frogs have been extensively use in research for their eggs, that can be collected following hormonal stimulation either naturally or by surgical intervention. Many anaesthetics have been used in amphibians such as bath solutions of MS-222, benzocaine and eugenol as well as systemic injections of ketamine or tiletamine, barbiturates, propofol and gas administrations of methoxyflurane, halothane and isoflurane. Most of these anaesthetic drugs produce variability in depth and duration of anaesthesia. MS-222 appears to be one of the most reliable anaesthetics. This review will focus on the evidence of pain perception in frogs and will compare the effectiveness and limitations of different anaesthetics used in Xenopus leavis frogs.

  17. Habitat use and home range of the endangered gold-spotted pond frog (Rana chosenica).

    PubMed

    Ra, Nam-Yong; Sung, Ha-Cheol; Cheong, Seokwan; Lee, Jung-Hyun; Eom, Junho; Park, Daesik

    2008-09-01

    Because of their complex life styles, amphibians and reptiles living in wetlands require both aquatic and terrestrial buffer zones in their protected conservation areas. Due to steep declines in wild populations, the gold-spotted pond frog (Rana chosenica) is listed as vulnerable by the IUCN. However, lack of data about its movements and use of habitat prevents effective conservation planning. To determine the habitat use and home range of this species, we radio-tracked 44 adult frogs for 37 days between 10 July and 4 Nov. 2007 to observe three different populations in the breeding season, non-breeding season, and late fall. The gold-spotted pond frog was very sedentary; its daily average movement was 9.8 m. Frogs stayed close to breeding ponds (within 6.6 m), and did not leave damp areas surrounding these ponds, except for dormancy migration to terrestrial sites such as dried crop fields. The average distance of dormancy migration of seven frogs from the edge of their breeding ponds was 32.0 m. The average size of an individual's home range was 713.8 m(2) (0.07 ha). The year-round population home range, which accounts for the home ranges of a population of frogs, was determined for two populations to be 8,765.0 m(2) (0.88 ha) and 3,700.9 m(2) (0.37 ha). Our results showed that to conserve this endangered species, appropriately sized wetlands and extended terrestrial buffer areas surrounding the wetlands (at least 1.33 ha, diameter 130 m) should be protected.

  18. Deformation Time-Series of the Lost-Hills Oil Field using a Multi-Baseline Interferometric SAR Inversion Algorithm with Finite Difference Smoothing Constraints

    NASA Astrophysics Data System (ADS)

    Werner, C. L.; Wegmüller, U.; Strozzi, T.

    2012-12-01

    The Lost-Hills oil field located in Kern County,California ranks sixth in total remaining reserves in California. Hundreds of densely packed wells characterize the field with one well every 5000 to 20000 square meters. Subsidence due to oil extraction can be grater than 10 cm/year and is highly variable both in space and time. The RADARSAT-1 SAR satellite collected data over this area with a 24-day repeat during a 2 year period spanning 2002-2004. Relatively high interferometric correlation makes this an excellent region for development and test of deformation time-series inversion algorithms. Errors in deformation time series derived from a stack of differential interferograms are primarily due to errors in the digital terrain model, interferometric baselines, variability in tropospheric delay, thermal noise and phase unwrapping errors. Particularly challenging is separation of non-linear deformation from variations in troposphere delay and phase unwrapping errors. In our algorithm a subset of interferometric pairs is selected from a set of N radar acquisitions based on criteria of connectivity, time interval, and perpendicular baseline. When possible, the subset consists of temporally connected interferograms, otherwise the different groups of interferograms are selected to overlap in time. The maximum time interval is constrained to be less than a threshold value to minimize phase gradients due to deformation as well as minimize temporal decorrelation. Large baselines are also avoided to minimize the consequence of DEM errors on the interferometric phase. Based on an extension of the SVD based inversion described by Lee et al. ( USGS Professional Paper 1769), Schmidt and Burgmann (JGR, 2003), and the earlier work of Berardino (TGRS, 2002), our algorithm combines estimation of the DEM height error with a set of finite difference smoothing constraints. A set of linear equations are formulated for each spatial point that are functions of the deformation velocities

  19. THE PROPELLER AND THE FROG

    SciTech Connect

    Pan, Margaret; Chiang, Eugene

    2010-10-20

    'Propellers' in planetary rings are disturbances in ring material excited by moonlets that open only partial gaps. We describe a new type of co-orbital resonance that can explain the observed non-Keplerian motions of propellers. The resonance is between the moonlet underlying the propeller and co-orbiting ring particles downstream of the moonlet where the gap closes. The moonlet librates within the gap about an equilibrium point established by co-orbiting material and stabilized by the Coriolis force. In the limit of small libration amplitude, the libration period scales linearly with the gap azimuthal width and inversely as the square root of the co-orbital mass. The new resonance recalls but is distinct from conventional horseshoe and tadpole orbits; we call it the 'frog' resonance, after the relevant term in equine hoof anatomy. For a ring surface density and gap geometry appropriate for the propeller Bleriot in Saturn's A ring, our theory predicts a libration period of {approx}4 years, similar to the {approx}3.7 year period over which Bleriot's orbital longitude is observed to vary. These librations should be subtracted from the longitude data before any inferences about moonlet migration are made.

  20. The Propeller and the Frog

    NASA Astrophysics Data System (ADS)

    Pan, Margaret; Chiang, Eugene

    2010-10-01

    "Propellers" in planetary rings are disturbances in ring material excited by moonlets that open only partial gaps. We describe a new type of co-orbital resonance that can explain the observed non-Keplerian motions of propellers. The resonance is between the moonlet underlying the propeller and co-orbiting ring particles downstream of the moonlet where the gap closes. The moonlet librates within the gap about an equilibrium point established by co-orbiting material and stabilized by the Coriolis force. In the limit of small libration amplitude, the libration period scales linearly with the gap azimuthal width and inversely as the square root of the co-orbital mass. The new resonance recalls but is distinct from conventional horseshoe and tadpole orbits; we call it the "frog" resonance, after the relevant term in equine hoof anatomy. For a ring surface density and gap geometry appropriate for the propeller Blériot in Saturn's A ring, our theory predicts a libration period of ~4 years, similar to the ~3.7 year period over which Blériot's orbital longitude is observed to vary. These librations should be subtracted from the longitude data before any inferences about moonlet migration are made.

  1. Primary combination of phase-field and discrete dislocation dynamics methods for investigating athermal plastic deformation in various realistic Ni-base single crystal superalloy microstructures

    NASA Astrophysics Data System (ADS)

    Gao, Siwen; Rajendran, Mohan Kumar; Fivel, Marc; Ma, Anxin; Shchyglo, Oleg; Hartmaier, Alexander; Steinbach, Ingo

    2015-10-01

    Three-dimensional discrete dislocation dynamics (DDD) simulations in combination with the phase-field method are performed to investigate the influence of different realistic Ni-base single crystal superalloy microstructures with the same volume fraction of {γ\\prime} precipitates on plastic deformation at room temperature. The phase-field method is used to generate realistic microstructures as the boundary conditions for DDD simulations in which a constant high uniaxial tensile load is applied along different crystallographic directions. In addition, the lattice mismatch between the γ and {γ\\prime} phases is taken into account as a source of internal stresses. Due to the high antiphase boundary energy and the rare formation of superdislocations, precipitate cutting is not observed in the present simulations. Therefore, the plastic deformation is mainly caused by dislocation motion in γ matrix channels. From a comparison of the macroscopic mechanical response and the dislocation evolution for different microstructures in each loading direction, we found that, for a given {γ\\prime} phase volume fraction, the optimal microstructure should possess narrow and homogeneous γ matrix channels.

  2. Frictional contact behaviour of the tyre: the effect of tread slip on the in-plane structural deformation and stress field development

    NASA Astrophysics Data System (ADS)

    Tsotras, Achillefs; Mavros, George

    2010-08-01

    The analysis of the in-plane deformation of the tyre in relation to the frictional contact between the road and the tread is a crucial first step in the understanding of its contribution to the longitudinal dynamics of a vehicle. In this work, the physical mechanism of the generation of the two-dimensional contact pressure distribution for a non-rolling tyre is studied. Towards this aim, a physical tyre model is constructed, consisting of an analytical ring under pretension, a non-linear sidewall foundation, and a discretised foundation of viscoelastic elements representing the tread. Tread behaviour is examined first, with focus on the development of shear micro-slip. The tread simulation is enhanced with the combination of radial and tangential tread elements and the benefits of such an approach are identified. Subsequently, the contact of the complete model is examined by implementing an algorithm for transient simulations in the time domain. The effects of the imposed vertical load and sidewall non-linearity on the contact stress and strain fields are identified. The modelling approach is validated by comparison with published experimental results. The physical mechanism that couples the torsional and horizontal/vertical deformations of the carcass with the frictional forces at the tread is identified and discussed in detail. The proposed modelling approach is found appropriate for the description of the development of the two-dimensional contact pressure field as a function of the frictional potential of the contact.

  3. Mapping of surface ruptures and crustal deformations by field investigations and PALSAR/InSAR for the 2008 Wenchuan Earthquake, China

    NASA Astrophysics Data System (ADS)

    Hao, K.; Si, H.; Fujiwara, H.; Ozawa, T.

    2009-12-01

    The 2008 Wenchuan earthquake (Mw 7.9) ruptured partial faults along the 500 km-length Longmen Shan (LMS) thrust faults, resulted in major damage to the areas more than 100,000 km2, the death toll over 87,400, and the homeless of five million. Three weeks later we investigated the fields of heavily damage-belts along the LMS faults. The challenges of fieldworks included road blocked by landslides, inaccessible high-mountain areas, and unexpectedly political restrictions. On the three-sets of field investigations we found over 10 sites of coseismic surface ruptures along Guanxian-Anxian(GX-AX), and Yingxiu-Beichuan fault (YX-BC). Of them the maximum reached ~5m horizontal and ~6m vertical displacements at Housheng along YX-BC fault, and ~2m vertical at Bailu along GX-AX fault. Moreover, the left-slip fault at Xiaoyudong between of the two LMS faults, ruptured ~2.8m horizontal, and 1.5m vertical displacements as well. However, the irregularly distributed surface fault-ruptures and the huge areas inaccessible still left unknown even if many distinguished faults reported. Using interferometric synthetic aperture radar (InSAR) technology and Phased Array L-band SAR sensor (PALSAR) equipped on Advanced Land Observing Satellite (ALOS), we captured the whole pictures of faults movements and crustal deformations from the two-sets of data before and after the event. The larger deformation zones where the data was out of correlation range, occurred over 300km length of LMS faults, with a width of ~30 km in southwestern section, ~10km in northeastern section. Therefore, we created a novel bi-fault-slip model based on the field and satellite information along the LMS faults. The Inversion analysis of the elastic half-space dislocation theory using InSAR interferogram resulted in the fault-slips distributions on the bi-fault-slip model. The surface fault-slips analyzed are similarly with the field results. Furthermore, simulation of the fault-slips reconstructed the

  4. Localization and characterization of adrenergic receptors on frog skin melanophores.

    PubMed

    Longshore, M A; Horowitz, J M

    1981-07-01

    The functional location of adrenergic binding sites was studied in frog skin melanophores by injecting norepinephrine (NE) outside and inside a melanophore. In 49 groups of cells (75% of the fields tested) iontophoretic injection of NE outside the cell caused melanosome aggregation in the target cell and/or in the field. In six cells in which a resting membrane potential was measured before and after intracellular injection (10-90 nA), NE elicited no change in melanosome configuration. Once the receptors were localized, the effect of temperature on these receptors was determined by measuring the reflectance of skins (an indication of melanosome aggregation or dispersion) in two populations of frogs treated with NE, Rana pipiens pipiens (with dominant alpha-receptors) and Rana berlandieri forreri (with dominant beta-receptors). NE (0.1 mM) caused melanosome aggregation in the former and dispersion in the latter tested at 12, 22, and 40 degrees C. The iontophoretic and reflectance results suggest that the binding site of the adrenergic receptor is located on the outer surface of the plasma membrane of melanophores and that alpha- and beta-receptors evoke aggregation and dispersion, respectively, within the temperature range of these experiments.

  5. Visual mate choice in poison frogs.

    PubMed

    Summers, K; Symula, R; Clough, M; Cronin, T

    1999-11-07

    We investigated female mate choice on the basis of visual cues in two populations of Dendrobates pumilio, the strawberry poison frog, from the Bocas del Toro Archipelago in Panama, Central America. Mate choice experiments were carried out by presenting subject females of each of two morphs of this species (orange and green) from two different island populations (Nancy Key and Pope Island) with object frogs (one of each morph) under glass at one end of a terrarium. Recorded calls were played simultaneously from behind both object frogs. The experiments were carried out under two light regimes: (i) white light, and (ii) relatively monochromatic filtered blue light. Subject females from each population displayed a significant preference for their own morph under white light, but not under blue light. These results indicate that female D. pumilio use visual cues in mate choice, and suggest that colour may be the visual cue they use.

  6. FROGS (Friends of Granites) Report, summer 1988

    NASA Astrophysics Data System (ADS)

    DeYoreo, J. J.; Wickham, Stephen M.; Miller, Calvin

    This is the second Eos-published FROGS Report. Our purpose is to disseminate information and stimulate thinking concerning felsic magmatism in general and granitoids in particular. We intend to publish semiannually information about events and publications that are relevant to the study of felsic rocks, brief updates on research being done by granitoid researchers, and commentaries on important new and/or controversial themes. FROGS Reports is critically dependent upon response by those with an interest in research on felsic rocks. Please keep me (Calvin Miller, 6028B, Vanderbilt Univ., Nashville TN 37235) informed about upcoming or recent conferences, major publications, etc. Also, send me your suggestions for topics for (and/or volunteer to write) pertinent commentaries for FROGS Reports.

  7. Frog skin epithelium: electrolyte transport and chytridiomycosis

    PubMed Central

    Campbell, Craig R.; Voyles, Jamie; Cook, David I.; Dinudom, Anuwat

    2012-01-01

    One unique physiological characteristic of frogs is that their main route for intake of water is across the skin. In these animals, the skin acts in concert with the kidney and urinary bladder to maintain electrolyte homeostasis. Water absorption across the skin is driven by the osmotic gradient that develops as a consequence of solute transport. Our recent study demonstrated that chytridiomycosis, an infection of amphibian skin by the fungal pathogen, Batrachochytrium dendrobatidis, inhibits epithelial Na+ channels, attenuating Na+ absorption through the skin. In frogs that become severely affected by this fungus, systemic depletion of Na+, K+ and Cl− is thought to cause deterioration of cardiac electrical function, leading to cardiac arrest. Here we review the ion transport mechanisms of frog skin, and discuss the effect of chytridiomycosis on these mechanisms. PMID:22182598

  8. Regeneration of lumbar dorsal root axons into the spinal cord of adult frogs (Rana pipiens), an HRP study.

    PubMed

    Liuzzi, F J; Lasek, R J

    1985-02-22

    Lumbar dorsal roots of adult frogs were crushed or cut and reanastomosed. Following survival times of up to 75 days, the regenerating dorsal roots were recut and anterogradely injury-filled with horseradish peroxidase. This revealed that in the adult frog, regenerating axons re-enter the spinal cord. Comparison of the distribution of these axons with that of normal dorsal root axons showed that there is a partial restoration of the segmental distribution in the gray matter. However, the long ascending sensory tract of the dorsal funiculus was not restored. The dorsal funiculus was markedly gliotic and had relatively few labelled, regenerated axons. The labelled axons that were seen in the dorsal funiculus either extended longitudinally for a distance just beneath the pia, apparently in association with the glia limitans, or traversed the region to enter the dorsal gray matter. Most of the large and small diameter axons that entered the gray matter did so by passing through the region of the dorsolateral fasciculus. Within the gray matter, small diameter, regenerated axons arborized in the region of the dorsal terminal field, a region that has been shown in the normal frog to receive cutaneous afferents only. Many large diameter axons, presumably muscle afferents, arborized in the ventral terminal field, a region shown in the normal frog to receive muscle afferents exclusively. However, many of these large diameter axons had arborizations that extended to both terminal fields, thus suggesting that some abberant connections are made during dorsal root regeneration in the adult frog.

  9. Trans-Hudsonian far-field deformation effects in the Rae foreland: An integrated geological-3D magnetic model

    NASA Astrophysics Data System (ADS)

    Percival, J. A.; Tschirhart, V.

    2017-03-01

    The intracratonic Rae cover sequence, deposited ca. 2.2-1.9 Ga, forms a useful marker for unravelling tectonic events that affected the Archean Rae Province at ca.2.0, 1.9 and 1.85 Ga. Polyphase deformation is recognized within the Rae cover rocks, including the 70 × 10 km Montresor belt, and attributed to distal effects of the ca. 1.85 Ga Trans-Hudson orogeny. In this contribution we explore the 3D geometry and structural history of the Montresor belt, previously considered to be a simple syncline lying unconformably on Archean basement. New geological, geophysical and geochronological results define a more complex history in which lower Montresor units were thrust-imbricated with basement gneisses and metamorphosed to the amphibolite facies. Mid-to upper greenschist facies upper Montresor units, exposed in an open synform, are superficially less deformed. However, using high-resolution aeromagnetic data and distinct magnetic marker units considered proxies for bedding, we constructed a set of forward models to explore the three-dimensional geometry of the belt. The re-analysis outlines a set of pre-synform structures defined by low-angle truncations of the magnetic markers. Geometric relationships indicate the presence of at least three faults at low angles to bedding, interpreted as D1 piggy-back thrusts, and bracketed by available geochronology between 1.924 and 1.87 Ga. D1 strain in the upper Montresor strata is significantly less intense than that further south in Rae cover rocks, consistent with a more distal foreland setting during the Trans-Hudson orogeny. The Montresor belt preserves a record of the Trans-Hudson tectonic style at relatively shallow crustal levels as a result of its foreland setting and structural history including a syn-orogenic extensional detachment event.

  10. A Multi-scale Thermomechanical-Solidification Model to Simulate the Transient Force Field Deforming an Aluminum 6061 Semisolid Weld

    NASA Astrophysics Data System (ADS)

    Zareie Rajani, H. R.; Phillion, A. B.

    2015-08-01

    Formation of hot cracks is strongly affected by the transient force field acting on the semisolid weld-base metal interface. This paper presents a model that numerically simulates such a transient force field as a function of welding parameters. The model consists of two modules: (1) By means of a granular model of solidification, the microstructure of the semisolid area within the weld is reconstructed in three dimensions; (2) Since the transient force field is developed through the mechanical interaction between the semisolid weld and its base metal, the mechanical response of the base metal to the solidification of the weld is then simulated through finite element analysis. The results show that changing welding parameters and welding constraints varies the transient force field. Based on the obtained force fields, a qualitative study is also conducted to predict the susceptibility of various welds to hot cracking.

  11. Pseudacris triseriata (western chorus frog) and Rana sylvatica (wood frog) chytridiomycosis

    USGS Publications Warehouse

    Rittman, S.E.; Muths, E.; Green, D.E.

    2003-01-01

    The chytrid fungus Batrachochytrium dendrobatidis is a known pathogen of anuran amphibians, and has been correlated with amphibian die-offs worldwide (Daszak et. al. 1999. Emerging Infectious Diseases 5:735-748). In Colorado, B. dendrobatidis has infected Boreal toads (Bufo boreas) (Muths et. al., in review) and has been identified on museum specimens of northern leopard frogs (Rana pipiens) (Carey et. al. 1999. Develop. Comp. Immunol. 23:459-472). We report the first verified case of chytrid fungus in chorus frogs (Pseudacris triseriata) and wood frogs (Rana sylvatica) in the United States. We collected seven P. triseriata, and two adult and two juvenile R. sylvatica in the Kawuneeche Valley in Rocky Mountain National Park (RMNP) during June 2001. These animals were submitted to the National Wildlife Health Center (NWHC) as part of an amphibian health evaluation in RMNP. Chorus frogs were shipped in one container. Wood frog adults and juveniles were shipped in two separate containers. Histological examinations of all chorus frogs and 3 of 4 wood frogs were positive for chytrid fungus infection. The fourth (adult) wood frog was too decomposed for meaningful histology. Histological findings consisted of multifocally mild to diffusely severe infections of the epidermis of the ventrum and hindlimb digital skin. Chytrid thalli were confined to the thickened epidermis (hyperkeratosis), were spherical to oval, and occasional thalli contained characteristic discharge pores or zoospores (Green and Kagarise Sherman 1999. J. Herpetol 35:92-103; Fellers et al. 2001. Copeia 2001:945-953). We cannot confirm that all specimens carried the fungus at collection, because infection may have spread from one individual to all other individuals in each container during transport. Further sampling of amphibians in Kawuneeche Valley is warranted to determine the rate of infection and mortality in these populations.

  12. Do all frogs swim alike? The effect of ecological specialization on swimming kinematics in frogs.

    PubMed

    Robovska-Havelkova, Pavla; Aerts, Peter; Rocek, Zbynek; Prikryl, Tomas; Fabre, Anne-Claire; Herrel, Anthony

    2014-10-15

    Frog locomotion has attracted wide scientific interest because of the unusual and derived morphology of the frog pelvic girdle and hind limb. Previous authors have suggested that the design of the frog locomotor system evolved towards a specialized jumping morphology early in the radiation of the group. However, data on locomotion in frogs are biased towards a few groups and most of the ecological and functional diversity remains unexplored. Here, we examine the kinematics of swimming in eight species of frog with different ecologies. We use cineradiography to quantify movements of skeletal elements from the entire appendicular skeleton. Our results show that species with different ecologies do differ in the kinematics of swimming, with the speed of limb extension and especially the kinematics of the midfoot being different. Our results moreover suggest that this is not a phylogenetic effect because species from different clades with similar ecologies converge on the same swimming kinematics. We conclude that it is important to analyze frog locomotion in a broader ecological and evolutionary context if one is to understand the evolutionary origins of this behavior.

  13. Time-Variable Geophysical Background Models for High-Frequency Non-Tidal Variability in the Earth's Gravity Field, its Surface Deformation, and its Rotation provided by GFZ

    NASA Astrophysics Data System (ADS)

    Dobslaw, Henryk; Dill, Robert; Bergmann-Wolf, Inga; Poropat, Lea; Thomas, Maik

    2016-04-01

    Mass variability in atmosphere, oceans, and the terrestrially stored water is reflected in time variations of the Earth's gravity field, its surface deformations, and its rotation that are reliably picked up by geodetic networks and satellite missions since many years. For studies attempting to unveil signatures of solid Earth processes from such observations, its is highly important to remove signals caused by geophysical fluids on or above the surface as accurately as possible. At this poster, we are going to give a summary about the current status of the time-variable geophysical background models suitable for geodetic purposes that are currently processed at GFZ Potsdam. This will include the latest versions of the GRACE AOD1B background model; effective angular momentum functions for atmosphere, oceans, and the continental hydrosphere; as well as surface deformations due to tidal and non-tidal mass loads on the continents and the ocean floor. Latest news and all access details to the datasets are available at http://www.gfz-potsdam.de/en/section/earthsystemmodelling/services.

  14. Anomalous Neutron Capture and Plastic Deformation of cu and pd Cathodes during Electrolysis in a Weak Thermalized Neutron Field:. Evidence of Nuclei-Lattice Exchange

    NASA Astrophysics Data System (ADS)

    Lipson, A. G.; Miley, G. H.; Lipson, A. G.

    2006-02-01

    Anomalous neutron capture and plastic deformation in the hardened Cu and Pd cathodes has been established under combined action of electrolysis and a weak thermalized neutron field (WTNF) with a flux in the range of 180-400 n/s cm2. Experiments with these cathodes showed ~7.0% decrease in the 2224 keV n-D gamma peak accompanying thermalized neutron capture inside the PE cavity during electrolysis vs. experiments with annealed Cu and Pd as well as with the background runs (i.e., no electrolysis). The anomalous neutron capture and plastic deformation of Cu and Pd cathodes under combined action of electrolysis and WTNF may be explained energetically by assuming a selective radiationless thermalized neutron capture at high-internal strain concentration sites in the hardened cathodes. The results of these experiments provide straightforward (avoids the Coulomb barrier penetration issue) evidence that nuclei-lattice energy exchange can result in an increase in neutron capture probability and radiationless de-excitation of the resulting compound nuclei.

  15. Carbaryl-induced histopathologic alterations on testes of levantine frog, Pelophylax bedriagae (Anura: Ranidae).

    PubMed

    Çakıcı, Özlem

    2013-07-01

    The aim of the study was to investigate for the first time histopathologic effects of carbaryl on the testes of adult frog, Pelophylax bedriagae. Frogs were exposed to carbaryl once by oral gavage in concentrations of 0.05, 0.1 and 0.2 mg/g. After 96 h, frogs were euthanized and dissected. Histopathological changes were more prominent in medium- (0.1 mg/g) and high-dose (0.2 mg/g) groups than in the low-dose (0.05 mg/g) group. In the low-dose group, shrinkage of some seminiferous tubules was observed. In the medium-dose group, an enlargement of interstitial spaces and germ cell necrosis were detected. In the high-dose group, prominent tubule deformation was determined. Germ cell necrosis in seminiferous tubules was frequently seen. In addition, congestion, hemorrhage, cellular infiltration and fibrosis were detected. According to these findings, it is clear that carbaryl affects male fertility in P. bedriagae.

  16. Does testosterone affect foraging behavior in male frogs?

    PubMed

    Desprat, Julia L; Mondy, Nathalie; Lengagne, Thierry

    2017-02-19

    During the breeding season, males often produce costly and extravagant displays or physical ornaments to attract females. Numerous studies have established that testosterone could directly influence the expression of certain sexual signals. However, few of these studies have focused on the indirect role that testosterone could play in modulating prey detection and visual performance to improve the foraging ability of males and hence their acquisition of nutritional resource. In the present study, we experimentally modified the testosterone levels of European tree frog males (Hyla arborea), staying in the natural range previously measured in the field, and we investigated the effect of testosterone on the foraging ability of individuals. Foraging capacities were measured on males placed in an arena with a virtual cricket moving on a computer screen. Our results demonstrated a significant effect of testosterone on the hunting behavior of H. arborea. We observed that testosterone reduced the orientation latency to virtual prey for supplemented males compared to controls. In addition, testosterone significantly increased the attack promptness of male frogs. Finally, our experiment did not demonstrate any impact of testosterone on male attack success.

  17. SU-D-BRA-05: Prostatectomy Patient's Bladder and Rectum Inter-Fraction Organ Motion and Deformation Can Be Described by a Gaussian Signed Distance Field.

    PubMed

    Hu, E; Zhou, S

    2012-06-01

    The inter-fraction organ motion/deformation can be conveniently modeled using Bayesian theory with Normal-gamma conjugate prior if signed distance from any fixed point in space to surface of the organ of interest obeys normal distribution. In this study, we investigated whether the inter-fraction motion/deformation of bladder and rectum observed from clinical prostatectomy patients satisfy this normality condition. 285 treatment planning CT and daily CT-on-rails scans from 7 prostatectomy patients were used in this study. Both bladder and rectum were contoured on all scans. Each patient's daily CT-on-rails scans were registered to his treatment planning CT and the bladder/rectum contours were mapped into treatment planning CT space for analysis. A cubic box with orientations along treatment planning CT image axes is defined to contain all bladders/rectums with 2cm margin. For each voxel inside this box (size: 2mm×2mm×1.5mm), its distance to the bladder/rectum surfaces was measured. Sign is added to the distance to indicate whether a point is inside or outside of an organ of interest. Now the inter-fraction motion/deformation of bladder/rectum can be characterized by the distance variation from the voxels to the bladder/rectum surface. Jarque-Bera normality statistical test was employed to examine whether the signed distances obey normal distribution. For each patient, the signed distance to bladder or rectum from at least 99.99% of the voxels passed the Jarque-Bera test with p-value 0.05. For prostatectomy patients, their bladder or rectum inter-fraction organ motion/deformation can be statistically described by a Gaussian signed distance field. This makes it possible to use Bayesian statistics model with Normal-gamma conjugate prior to predict bladder or rectum daily location and shape during a prostatectomy patient fractionated radiotherapy. © 2012 American Association of Physicists in Medicine.

  18. Shear deformation and division of cylindrical walls in free-standing nematic films under high electric fields.

    PubMed

    Tadapatri, Pramod; Krishnamurthy, K S

    2008-10-30

    We report on the behavior of cylindrical walls formed in a substrate-free nematic film of PCH5 under the action of an in-plane ac field. In the film, with vertical molecular alignment at all the limiting surfaces, annular Brochard-Leger walls are induced well above the bend-Freedericksz threshold. They exhibit, at high field strengths, a new type of instability not encountered in sandwich, or any other, cell configuration. It manifests as a shearing of the loop-wall between the opposite free-surfaces. The shear strain is measured as a function of time, field strength, frequency, and temperature. Significantly, the strain is linear in field strength. The origin of shear and its dependence on field variables are explained through an adaptation of the Carr-Helfrich mechanism of charge separation. The sheared wall is stable against pincement up to several times the threshold field, and divides itself into two fragments under a large enough strain. With the shear distortion, linear defects appear in the opposite splay-bend regions, just as Neel lines in Bloch walls of magnetic systems. At very low frequencies, flexoelectric influence on distortion is revealed.

  19. Return of the Tarahumara frog to Arizona

    Treesearch

    James C. Rorabaugh; Stephen F. Hale; Michael J. Sredl; Craig Ivanyi

    2005-01-01

    The last wild Tarahumara frog (Rana tarahumarae) in Arizona was found dead in Big Casa Blanca Canyon, Santa Rita Mountains, in May 1983. However, the species is still well represented in the majority of its range in the northern Sierra Madre Occidental and adjacent Sky Islands of Sonora and Chihuahua. Plans to re-establish R. tarahumarae...

  20. Frog egg growth, experiment S003

    NASA Technical Reports Server (NTRS)

    Young, R. S.; Tremor, J. W.

    1971-01-01

    The objective of experiment was to determine the effect of weightlessness on the ability of a fertilized frog egg to divide normally and to differentiate and form a normal embryo. This experiment was first attempted on the Gemini 8 mission and was completed only partially because of the early termination of that mission.

  1. Frogs report: Friends of Granite, Winter 1990

    NASA Astrophysics Data System (ADS)

    FROGS reports present information on current research relevant to felsic magmatism, including commentaries on problems of current interest. Please contact Calvin Miller (Geology, 6028B, Vanderbilt University, Nashville, TN 37235, tel. 615-322-2986) about your own research, conferences, and ideas for stimulating commentaries.

  2. Fatal attraction: adaptations to prey on native frogs imperil snakes after invasion of toxic toads.

    PubMed

    Hagman, Mattias; Phillips, Benjamin L; Shine, Richard

    2009-08-07

    Adaptations that enhance fitness in one situation can become liabilities if circumstances change. In tropical Australia, native snake species are vulnerable to the invasion of toxic cane toads. Death adders (Acanthophis praelongus) are ambush foragers that (i) attract vertebrate prey by caudal luring and (ii) handle anuran prey by killing the frog then waiting until the frog's chemical defences degrade before ingesting it. These tactics render death adders vulnerable to toxic cane toads (Bufo marinus), because toads elicit caudal luring more effectively than do native frogs, and are more readily attracted to the lure. Moreover, the strategy of delaying ingestion of a toad after the strike does not prevent fatal poisoning, because toad toxins (unlike those of native frogs) do not degrade shortly after the prey dies. In our laboratory and field trials, half of the death adders died after ingesting a toad, showing that the specialized predatory behaviours death adders use to capture and process prey render them vulnerable to this novel prey type. The toads' strong response to caudal luring also renders them less fit than native anurans (which largely ignored the lure): all toads bitten by adders died. Together, these results illustrate the dissonance in behavioural adaptations that can arise following the arrival of invasive species, and reveal the strong selection that occurs when mutually naive species first interact.

  3. Bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers in wild frogs.

    PubMed

    Liu, Peng-Yan; Du, Guo-Dong; Zhao, Ya-Xian; Mu, Yun-Song; Zhang, Ai-Qian; Qin, Zhan-Fen; Zhang, Xiao-You; Yan, Shi-Shuai; Li, Yan; Wei, Rong-Guo; Qin, Xiao-Fei; Yang, Yong-Jian

    2011-08-01

    To investigate bioaccumulation, maternal transfer and elimination of polybrominated diphenyl ethers (PBDEs) in amphibians, we collected adult frogs (Rana limnocharis) from a rice field in an e-waste recycling site in China. We found that ∑PBDEs in the whole frogs and various tissues (brain, liver, testis and egg) ranged from 17.10 to 141.11 ng g(-1) wet weight. Various tissues exhibited a similar PBDE congener profile, which was characterized by intermediate brominated congeners (BDE-99 and BDE-153) as the largest contributors, with less lower brominated congeners (BDE-28 and BDE-47) and higher brominated congeners (BDE-209). The maternal transfer capacity of PBDEs declined with the increase in bromine numbers of PBDE congeners. We suggest that the bromine atom number (the molecular size, to some degree) might be a determining factor for the maternal transport of a PBDE congener rather than K(ow) (Octanol-Water partition coefficient), which expresses a compound's lipophilicity. ∑PBDEs concentrations in frogs decreased over time during a depuration period of 54 days when these wild frogs were brought to the lab from the e-waste recycling site. The half-life of ∑PBDEs was 35 days, with about 14 days for BDE-47, and 36 and 81 days for BDE-99 and BDE-153, respectively. The data shows that the elimination of PBDEs has no essential difference from aquatic and terrestrial species.

  4. Endemic infection of the amphibian chytrid fungus in a frog community post-decline.

    PubMed

    Retallick, Richard W R; McCallum, Hamish; Speare, Rick

    2004-11-01

    The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

  5. Asymmetrical effects of introduced Rana catesbeiana on native ranid frogs in Oregon, USA

    USGS Publications Warehouse

    Pearl, Christopher A.; Adams, Michael J.; Bury, R. Bruce; McCreary, B.

    2004-01-01

    Introduced American Bullfrogs (Rana catesbeiana) have become widely established in the Pacific Northwest over the last century and are thought to be an important predator of native amphibians throughout the western United States. The Northern Red-Legged Frog (Rana aurora aurora) and Oregon Spotted Frog (Rana pretiosa) historically coexisted in portions of the Pacific Northwest now invaded by R. catesbeiana, but R. pretiosa has declined more severely than R. a. aurora. We investigated whether microhabitat and behavioral differences that facilitate sympatric coexistence of the natives predict which species is more susceptible to predation by introduced R. catesbeiana. Our laboratory experiments demonstrate that R. catesbeiana adults prefer aquatic microhabitats, that R. pretiosa juveniles are more aquatic than R. a. aurora, and that adult R. catesbeiana consume more R. pretiosa than R. a. aurora juveniles. Mean and maximum jump distances of R. pretiosa were shorter than equally sized R. a. aurora, and the difference between these two species increased with larger frog sizes. Our examination of field survey data indicates that R. pretiosa coexist with R. catesbeiana less frequently than R. a. aurora. We conclude that R. catesbeiana is a greater threat to survival of R. pretiosa than to R. a. aurora and suggest that microhabitat use and escape abilities of native ranid frogs may be linked to this asymmetrical effect. Analysis of behavioral and microhabitat differences among related native species may be a useful tool in predicting the effects of introduced predators on amphibians and can assist in developing conservation priorities for these species.

  6. Asymmetrical Effects of Introduced Bullfrogs (Rana catesbeiana) on Native Ranid Frogs in Oregon

    USGS Publications Warehouse

    Pearl, C.A.; Adams, M.J.; Bury, R.B.; McCreary, B.

    2004-01-01

    Introduced American Bullfrogs (Rana catesbeiana) have become widely established in the Pacific Northwest over the last century and are thought to be an important predator of native amphibians throughout the western United States. The Northern Red-Legged Frog (Rana aurora aurora) and Oregon Spotted Frog (Rana pretiosa) historically coexisted in portions of the Pacific Northwest now invaded by R. catesbeiana, but R. pretiosa has declined more severely than R. a. aurora. We investigated whether microhabitat and behavioral differences that facilitate sympatric coexistence of the natives predict which species is more susceptible to predation by introduced R. catesbeiana. Our laboratory experiments demonstrate that R. catesbeiana adults prefer aquatic microhabitats, that R. pretiosa juveniles are more aquatic than R. a. aurora, and that adult R. catesbeiana consume more R. pretiosa than R. a. aurora juveniles. Mean and maximum jump distances of R. pretiosa were shorter than equally sized R. a. aurora, and the difference between these two species increased with larger frog sizes. Our examination of field survey data indicates that R. pretiosa coexist with R. catesbeiana less frequently than R. a. aurora. We conclude that R. catesbeiana is a greater threat to survival of R. pretiosa than to R. a. aurora and suggest that microhabitat use and escape abilities of native ranid frogs may be linked to this asymmetrical effect. Analysis of behavioral and microhabitat differences among related native species may be a useful tool in predicting the effects of introduced predators on amphibians and can assist in developing conservation priorities for these species.

  7. Diamagnetic levitation: Flying frogs and floating magnets (invited)

    NASA Astrophysics Data System (ADS)

    Simon, M. D.; Geim, A. K.

    2000-05-01

    Contrary to our intuition, apparently nonmagnetic substances can be levitated in a magnetic field and can stabilize free levitation of a permanent magnet. Most substances are weakly diamagnetic and the tiny forces associated with this property make the two types of levitation possible. Living things mostly consist of diamagnetic molecules (such as water and proteins) and components (such as bones) and therefore can be levitated and can experience low gravity. In this way, frogs have been able to fly in the throat of a high field magnet. Stable levitation of one magnet by another with no energy input is usually prohibited by Earnshaw's Theorem. However, the introduction of diamagnetic material at special locations can stabilize such levitation. A magnet can even be stably suspended between (diamagnetic) fingertips.

  8. Haglund's Deformity

    MedlinePlus

    ... deformity is often called “pump bump” because the rigid backs of pump-style shoes can create pressure ... when walking. In fact, any shoes with a rigid back, such as ice skates, men’s dress shoes ...

  9. Contracture deformity

    MedlinePlus

    Deformity - contracture ... Contracture can be caused by any of the following: Brain and nervous system disorders, such as cerebral ... Follow your health care provider's instructions for treating contracture at home. Treatments may include: Doing exercises and ...

  10. Fundamental study on a gene transfection methodology for mammalian cells using water-in-oil droplet deformation in a DC electric field.

    PubMed

    Kurita, Hirofumi; Takao, Yasuhiro; Kishikawa, Kenta; Takashima, Kazunori; Numano, Rika; Mizuno, Akira

    2016-12-01

    We have developed a gene transfection method called water-in-oil droplet electroporation (EP) that uses a dielectric oil and a liquid droplet containing live cells and exogenous DNA. When a cell suspension droplet is placed between a pair of electrodes, an intense DC electric field can induce droplet deformation, resulting in an instantaneous short circuit caused by the droplet elongating and contacting the two electrodes simultaneously. Small transient pores are generated in the cell membrane during the short, allowing the introduction of exogenous DNA into the cells. The droplet EP was characterized by varying the following experimental parameters: applied voltage, number of short circuits, type of medium (electric conductivity), concentration of exogenous DNA, and size of the droplet. In addition, the formation of transient pores in the cell membrane during droplet EP and the transfection efficiency were evaluated.

  11. Spinal deformity.

    PubMed

    Bunnell, W P

    1986-12-01

    Spinal deformity is a relatively common disorder, particularly in teenage girls. Early detection is possible by a simple, quick visual inspection that should be a standard part of the routine examination of all preteen and teenage patients. Follow-up observation will reveal those curvatures that are progressive and permit orthotic treatment to prevent further increase in the deformity. Spinal fusion offers correction and stabilization of more severe degrees of scoliosis.

  12. Hyperspectral analysis of columbia spotted frog habitat

    USGS Publications Warehouse

    Shive, J.P.; Pilliod, D.S.; Peterson, C.R.

    2010-01-01

    Wildlife managers increasingly are using remotely sensed imagery to improve habitat delineations and sampling strategies. Advances in remote sensing technology, such as hyperspectral imagery, provide more information than previously was available with multispectral sensors. We evaluated accuracy of high-resolution hyperspectral image classifications to identify wetlands and wetland habitat features important for Columbia spotted frogs (Rana luteiventris) and compared the results to multispectral image classification and United States Geological Survey topographic maps. The study area spanned 3 lake basins in the Salmon River Mountains, Idaho, USA. Hyperspectral data were collected with an airborne sensor on 30 June 2002 and on 8 July 2006. A 12-year comprehensive ground survey of the study area for Columbia spotted frog reproduction served as validation for image classifications. Hyperspectral image classification accuracy of wetlands was high, with a producer's accuracy of 96 (44 wetlands) correctly classified with the 2002 data and 89 (41 wetlands) correctly classified with the 2006 data. We applied habitat-based rules to delineate breeding habitat from other wetlands, and successfully predicted 74 (14 wetlands) of known breeding wetlands for the Columbia spotted frog. Emergent sedge microhabitat classification showed promise for directly predicting Columbia spotted frog egg mass locations within a wetland by correctly identifying 72 (23 of 32) of known locations. Our study indicates hyperspectral imagery can be an effective tool for mapping spotted frog breeding habitat in the selected mountain basins. We conclude that this technique has potential for improving site selection for inventory and monitoring programs conducted across similar wetland habitat and can be a useful tool for delineating wildlife habitats. ?? 2010 The Wildlife Society.

  13. 3-D Deformation Field Of The 2010 El Mayor-Cucapah (Mexico) Earthquake From Matching Before To After Aerial Lidar Point Clouds

    NASA Astrophysics Data System (ADS)

    Hinojosa-Corona, A.; Nissen, E.; Arrowsmith, R.; Krishnan, A. K.; Saripalli, S.; Oskin, M. E.; Arregui, S. M.; Limon, J. F.

    2012-12-01

    The Mw 7.2 El Mayor-Cucapah earthquake (EMCE) of 4 April 2010 generated a ~110 km long, NW-SE trending rupture, with normal and right-lateral slip in the order of 2-3m in the Sierra Cucapah, the northern half, where the surface rupture has the most outstanding expression. Vertical and horizontal surface displacements produced by the EMCE have been addressed separately by other authors with a variety of aerial and satellite remote sensing techniques. Slip variation along fault and post-seismic scarp erosion and diffusion have been estimated in other studies using terrestrial LiDAR (TLS) on segments of the rupture. To complement these other studies, we computed the 3D deformation field by comparing pre- to post-event point clouds from aerial LiDAR surveys. The pre-event LiDAR with lower point density (0.013-0.033 pts m-2) required filtering and post-processing before comparing with the denser (9-18 pts m-2) more accurate post event dataset. The 3-dimensional surface displacement field was determined using an adaptation of the Iterative Closest Point (ICP) algorithm, implemented in the open source Point Cloud Library (PCL). The LiDAR datasets are first split into a grid of windows, and for each one, ICP iteratively converges on the rigid body transformation (comprising a translation and a rotation) that best aligns the pre- to post-event points. Testing on synthetic datasets perturbed with displacements of known magnitude showed that windows with dimensions of 100-200m gave the best results for datasets with these densities. Here we present the deformation field with detailed displacements in segments of the surface rupture where its expression was recognized by ICP from the point cloud matching, mainly the scarcely vegetated Sierra Cucapah with the Borrego and Paso Superior fault segments the most outstanding, where we are able to compare our results with values measured in the field and results from TLS reported in other works. EMC simulated displacement field for a

  14. Free vibration of conducting nanoplates exposed to unidirectional in-plane magnetic fields using nonlocal shear deformable plate theories

    NASA Astrophysics Data System (ADS)

    Kiani, Keivan

    2014-03-01

    The alteration of the frequencies of nanostructures via an external field is of great importance in the design of nanomechanical devices whose vibrations should be appropriately controlled. Herein, free in-plane and out-of-plane vibration behaviors of conducting rectangular nanoplates subjected to unidirectional in-plane steady magnetic fields are of concern. To this end, the body forces exerted on the nanoplate based on the hypotheses of Kirchhoff, Mindlin, and higher-order plate theories are obtained. Subsequently, the nonlocal versions of the equations of motion of the conducting nanoplate for the suggested plate models are extracted. The presented formulations show that the small-scale parameter is incorporated into the exerted forces on the nanoplate due to the applied magnetic field. For the proposed models, the frequencies pertinent to the in-plane and out-of-plane vibrations of the nanoplates are evaluated. In the continuing, the roles of the length-to-thickness ratio, length-to-width ratio, small-scale parameter, and magnetic field strength on both in-plane and out-of-plane frequencies are addressed. The capabilities of the proposed models in predicting such frequencies are also explained and discussed.

  15. Digital sampling Moiré as a substitute for microscope scanning Moiré for high-sensitivity and full-field deformation measurement at micron/nano scales.

    PubMed

    Wang, Qinghua; Ri, Shien; Tsuda, Hiroshi

    2016-09-01

    This study proposed to generate digital sampling Moiré fringes by two-pixel down-sampling as a substitute for microscope scanning Moiré fringes, and further reconstruct multiplication Moiré fringes for micron/nano-scale deformation measurement. The displacement and strain sensitivities of the proposed reconstructed multiplication Moiré method are 2 times higher in a wide field of view. Besides, two-dimensional deformation is easily measurable without rotating the sample stage or the scanning lines, no matter whether the scanning resolution is adjustable or not. As an example, the deformations of a carbon fiber reinforced plastic specimen were measured and analyzed. The proposed method effectively expands the application range of the Moiré technique to deformation measurement.

  16. Assessment of the metrological performance of an in situ storage image sensor ultra-high speed camera for full-field deformation measurements

    NASA Astrophysics Data System (ADS)

    Rossi, Marco; Pierron, Fabrice; Forquin, Pascal

    2014-02-01

    Ultra-high speed (UHS) cameras allow us to acquire images typically up to about 1 million frames s-1 for a full spatial resolution of the order of 1 Mpixel. Different technologies are available nowadays to achieve these performances, an interesting one is the so-called in situ storage image sensor architecture where the image storage is incorporated into the sensor chip. Such an architecture is all solid state and does not contain movable devices as occurs, for instance, in the rotating mirror UHS cameras. One of the disadvantages of this system is the low fill factor (around 76% in the vertical direction and 14% in the horizontal direction) since most of the space in the sensor is occupied by memory. This peculiarity introduces a series of systematic errors when the camera is used to perform full-field strain measurements. The aim of this paper is to develop an experimental procedure to thoroughly characterize the performance of such kinds of cameras in full-field deformation measurement and identify the best operative conditions which minimize the measurement errors. A series of tests was performed on a Shimadzu HPV-1 UHS camera first using uniform scenes and then grids under rigid movements. The grid method was used as full-field measurement optical technique here. From these tests, it has been possible to appropriately identify the camera behaviour and utilize this information to improve actual measurements.

  17. Near-Field Deformation Associated with the South Napa Earthquake (M 6.0) Using Differential Airborne LiDAR

    NASA Astrophysics Data System (ADS)

    Hudnut, K. W.; Glennie, C. L.; Brooks, B. A.; Hauser, D. L.; Ericksen, T.; Boatwright, J.; Rosinski, A.; Dawson, T. E.; Mccrink, T. P.; Mardock, D. K.; Hoirup, D. F., Jr.; Bray, J.

    2014-12-01

    Pre-earthquake airborne LiDAR coverage exists for the area impacted by the M 6.0 South Napa earthquake. The Napa watershed data set was acquired in 2003, and data sets were acquired in other portions of the impacted area in 2007, 2010 and 2014. The pre-earthquake data are being assessed and are of variable quality and point density. Following the earthquake, a coalition was formed to enable rapid acquisition of post-earthquake LiDAR. Coordination of this coalition took place through the California Earthquake Clearinghouse; consequently, a commercial contract was organized by Department of Water Resources that allowed for the main fault rupture and damaged Browns Valley area to be covered 16 days after the earthquake at a density of 20 points per square meter over a 20 square kilometer area. Along with the airborne LiDAR, aerial imagery was acquired and will be processed to form an orthomosaic using the LiDAR-derived DEM. The 'Phase I' airborne data were acquired using an Optech Orion M300 scanner, an Applanix 200 GPS-IMU, and a DiMac ultralight medium format camera by Towill. These new data, once delivered, will be differenced against the pre-earthquake data sets using a newly developed algorithm for point cloud matching, which is improved over prior methods by accounting for scan geometry error sources. Proposed additional 'Phase II' coverage would allow repeat-pass, post-earthquake coverage of the same area of interest as in Phase I, as well as an addition of up to 4,150 square kilometers that would potentially allow for differential LiDAR assessment of levee and bridge impacts at a greater distance from the earthquake source. Levee damage was reported up to 30 km away from the epicenter, and proposed LiDAR coverage would extend up to 50 km away and cover important critical lifeline infrastructure in the western Sacramento River delta, as well as providing full post-earthquake repeat-pass coverage of the Napa watershed to study transient deformation.

  18. Focal mechanisms in the southern Aegean from temporary seismic networks - implications for the regional stress field and ongoing deformation processes

    NASA Astrophysics Data System (ADS)

    Friederich, W.; Brüstle, A.; Küperkoch, L.; Meier, T.; Lamara, S.; Egelados Working Group

    2014-05-01

    The lateral variation of the stress field in the southern Aegean plate and the subducting Hellenic slab is determined from recordings of seismicity obtained with the CYCNET and EGELADOS networks in the years from 2002 to 2007. First motions from 7000 well-located microearthquakes were analysed to produce 540 well-constrained focal mechanisms. They were complemented by another 140 derived by waveform matching of records from larger events. Most of these earthquakes fall into 16 distinct spatial clusters distributed over the southern Aegean region. For each cluster, a stress inversion could be carried out yielding consistent estimates of the stress field and its spatial variation. At crustal levels, the stress field is generally dominated by a steeply dipping compressional principal stress direction except in places where coupling of the subducting slab and overlying plate come into play. Tensional principal stresses are generally subhorizontal. Just behind the forearc, the crust is under arc-parallel tension whereas in the volcanic areas around Kos, Columbo and Astypalea tensional and intermediate stresses are nearly degenerate. Further west and north, in the Santorini-Amorgos graben and in the area of the islands of Mykonos, Andros and Tinos, tensional stresses are significant and point around the NW-SE direction. Very similar stress fields are observed in western Turkey with the tensional axis rotated to NNE-SSW. Intermediate-depth earthquakes below 100 km in the Nisyros region indicate that the Hellenic slab experiences slab-parallel tension at these depths. The direction of tension is close to east-west and thus deviates from the local NW-oriented slab dip presumably owing to the segmentation of the slab. Beneath the Cretan sea, at shallower levels, the slab is under NW-SE compression. Tensional principal stresses in the crust exhibit very good alignment with extensional strain rate principal axes derived from GPS velocities except in volcanic areas, where both

  19. On the measurement of shear elastic moduli and viscosities of erythrocyte plasma membranes by transient deformation in high frequency electric fields.

    PubMed Central

    Engelhardt, H; Sackmann, E

    1988-01-01

    We present a new method to measure the shear elastic moduli and viscosities of erythrocyte membranes which is based on the fixation and transient deformation of cells in a high-frequency electric field. A frequency domain of constant force (arising by Maxwell Wagner polarization) is selected to minimize dissipative effects. The electric force is thus calculated by electrostatic principles by considering the cell as a conducting body in a dielectric fluid and neglecting membrane polarization effects. The elongation A of the cells perpendicular to their rotational axis exhibits a linear regime (A proportional to Maxwell tension or to square of the electric field E2) at small, and a nonlinear regime (A proportional to square root of Maxwell tension or to the electric field E) at large extensions with a cross-over at A approximately 0.5 micron. The nonlinearity leads to amplitude-dependent response times and to differences of the viscoelastic response and relaxation functions. The cells exhibit pronounced yet completely reversible tip formations at large extensions. Absolute values of the shear elastic modulus, mu, and membrane viscosity, eta, are determined by assuming that field-induced stretching of the biconcave cell may be approximately described in terms of a sphere to ellipsoid deformation. The (nonlinear) elongation-vs.-force relationship calculated by the elastic theory of shells agress well with the experimentally observed curves and the values of mu = 6.1 x 10(-6) N/m and eta = 3.4 x 10(-7) Ns/m are in good agreement with the micropipette results of Evans and co-workers. The effect of physical, biochemical, and disease-induced structural changes on the viscoelastic parameters is studied. The variability of mu and eta of a cell population of a healthy donor is +/- 45%, which is mainly due to differences in the cell age. The average mu value of cells of different healthy donors scatters by +/- 18%. Osmotic deflation of the cells leads to a fivefold increase of

  20. Lensing Signals in the Hubble Ultra-deep Field using all 2nd-order Shape Deformations

    SciTech Connect

    Irwin, John; Shmakova, Marina; Anderson, Jay; /Rice U.

    2006-07-17

    The long exposure times of the HST Ultra-Deep Field plus the use of an empirically derived position-dependent PSF, have enabled us to measure a cardioid/displacement distortion map coefficient as well as improving upon the sextupole map coefficient. We confirmed that curved background galaxies are clumped on the same angular scale as found in the HST Deep Field North. The new cardioid/displacement map coefficient is strongly correlated to a product of the sextupole and quadrupole coefficients. One would expect to see such a correlation from fits to background galaxies with quadrupole and sextupole moments. Events that depart from this correlation are expected to arise from map coefficient changes due to lensing, and several galaxy subsets selected using this criteria are indeed clumped.

  1. Experimental investigations of electric current under transverse and longitudinal electric field in uniaxially deformed p-Ge

    NASA Astrophysics Data System (ADS)

    Abramov, A. A.; Akimov, V. I.; Dalakyan, A. T.; Tulupenko, Victor N.; Zaitsev, A. M.; Danilov, S. N.; Firsov, D. A.; Shalygin, V. A.

    1999-11-01

    Comparison between cases of longitudinal and transverse directions of uniaxial pressure and strong electric field, affected the bulk hole germanium, to use it for lasting in far IR region has been carried out. Conclusion about preference of crossed directions is made. Threshold pressure, at which stimulated radiation arises, independence of crystallographic direction, along which external influences are applied, is also discussed. The results of experimental investigations of the crossed directions of uniaxial pressure and electric current are given.

  2. Magnetic-Field Hazards Bibliography.

    DTIC Science & Technology

    1985-09-01

    Puchalska, I. B., Influence of magnetic fields on frog sciatic nerve , Biochem. Biophys. Res. Comm. 91:118 (1979). 35. Fardon, 3. C., "Effect of magnetic...fields, Bioelectromagnetic 2:357 (1981). 41. Gaffey, C. T. and Tenforde, T. S., Bioelectric properties of frog sciatic nerves during exposure to...available from: U.S. Dept. of Energy, Bonneville Power Administration, Portland, Oregon 97208 (1982). 29. Levy , R. H., and Jones, G. S., "Plasma

  3. Focal mechanisms in the Southern Aegean from temporary seismic networks - implications for the regional stress field and ongoing deformation processes

    NASA Astrophysics Data System (ADS)

    Friederich, W.; Brüstle, A.; Küperkoch, L.; Meier, T.

    2013-10-01

    The lateral variation of the stress field in the southern Aegean plate and the subducting Hellenic slab is determined from recordings of seismicity obtained with the CYCNET and EGELADOS networks in the years from 2002 to 2007. First motions from 7000 well-located earthquakes were analysed to produce 540 well-constrained focal mechanisms. They were complemented by another 140 derived by waveform matching of records from larger events. Most of these earthquakes fall into 16 distinct spatial clusters distributed over the southern Aegean region. For each cluster, a stress inversion could be carried out yielding consistent estimates of the stress field and its spatial variation. At crustal levels, the stress field is generally dominated by a steeply dipping compressional principal stress direction except in places where coupling of the subducting slab and overlying plate come into play. Tensional principal stresses are generally subhorizontal. Just behind the forearc, the crust is under arc-parallel tension whereas in the volcanic areas around Kos, Columbo and Astypalea tensional and intermediate stresses are nearly degenerate. Further west and north, in the Santorini-Amorgos graben and in the area of the islands of Mykonos, Andros and Tinos, tensional stresses are significant and point around the NW-SE direction. Very similar stress fields are observed in western Turkey with the tensional axis rotated to NNE-SSW. Intermediate depth earthquakes below 100 km in the Nisyros region indicate that the Hellenic slab experiences slab-parallel tension at these depths. The direction of tension is close to east-west and thus deviates from the local NW-oriented slab dip presumably owing to the segmentation of the slab. Beneath the Cretan sea, at shallower levels, the slab is under NW-SE compression. The lateral and depth variations of the stress field reflect the various agents that influence tectonics in the Aegean: subduction of the Hellenic slab, incipient collision with

  4. Application and assessment of ultrasonic inspection methods for flaw detection and characterization of manganese steel frogs

    NASA Astrophysics Data System (ADS)

    Cinson, A.; Diaz, A.; Prowant, M.

    2011-04-01

    Ultrasonic nondestructive examination (NDE) has a long and successful history of application across a wide array of industries, including nuclear, aerospace, and transportation sectors. In coarse-grained, cast Manganese (Mn) steel frog components, NDE/inspection challenges are encountered both in-field (after the frogs have been installed on a rail line) and at the manufacturing facilities during post-fabrication QA/QC activities. Periodically inherently flawed frogs are received from a manufacturer, and put into service, as most railroad operators do not have a means to conduct pre-service examinations on received components. Accordingly, there is a need for a pre-service inspection system that can provide a rapid, cost-effective and non-intrusive inspection capability for detection of defects, flaws, and other anomalies in frog components, in order to avoid premature initiation of cracks or failures of these components during service. This study focused on evaluating use of a volumetric phased-array ultrasonic testing (PA-UT) method to monitor fabrication quality assurance. In this preliminary assessment of using PA-UT, data were acquired at a frequency of 2.0 MHz on a known, flawed Mn steel frog component directly from a manufacturing facility. The component contained flaws commonly found as a result of the manufacturing process of these cast rail components. The data were analyzed and the anomalies were detected, localized and characterized. Results were compared against baseline radiographic data. A detection metric was reported in the form of signal-to-noise values.

  5. STS-54 MS3 Helms uses DSO 802 & Physics of Toys frog toy on OV-105's middeck

    NASA Image and Video Library

    1993-01-15

    STS054-S-021 (15 Jan 1993) --- Helms with a frog swimmer toy on the middeck demonstrates some of the physics of toys to students watching on television. Four schools were chosen to ask questions of the astronauts during the lengthy program. Helms fielded questions from students at Shaver Elementary School in Portland, Oregon. The swimmer frog was used to demonstrate Newton's third law of motion and the conservation of angular momentum. The entire collection of toys will be videotaped for an educational program to be distributed to schools in the fall of this year. The scene was recorded at 17:51:38:12 GMT, Jan. 15, 1993.

  6. Effects of 4-tert-Octylphenol on the incubation of eggs in Japanese brown frogs (Rana japonica).

    PubMed

    Kawaguchi, Hiroaki; Umekita, Yoshihisa; Souda, Masakazu; Yoshida, Hiroki

    2008-01-01

    4-tert-Octylphenol (OP), is an endocrine disruptor or surfactant widely used in herbicides. Its effects (0, 1 and 10 mg/l) on the incubation of eggs were examined using wild Japanese brown frogs (Rana japonica). In 10 mg/l OP, all the eggs were corrupted and no eggs developed. In 1 mg/l OP, 9.8% eggs developed and systemic edema, malformations such as crooked vertebrae and atrophy of the systemic muscles were observed in all the surviving tadpoles. These results suggested that OP use in paddy fields may affect the survival rate of wild frogs and induce malformation.

  7. Finite Plane and Anti-Plane Elastostatic Fields with Discontinuous Deformation Gradients Near the Tip of a Crack.

    DTIC Science & Technology

    1982-07-01

    which makes no use of the hodograph transformation. The advantage of the procedure used here lies in its applicability to the plane strain Mode I problem...solutions of the displacement equation of equilibrium valid on overlapping domains . The final solution is then generated by a consistent matching...y(x)=x+u(x) for all xE%, (1.1)1 is a mappi;: of 9 onto a domain 6* in which u(x) is the displace- ment field. We assume the transformation (1.1) to be

  8. Role of the Low-Frequency Deformation Field on the Explosive Growth of Extratropical Cyclones at the Jet Exit. Part I: Barotropic Critical Region.

    NASA Astrophysics Data System (ADS)

    Rivière, G.; Joly, A.

    2006-08-01

    By using new theoretical results on perturbation growth in spatially and temporally complex quasigeostrophic flows, this paper investigates the role of the large-scale deformation field on extratropical cyclones and especially on their explosive growth in the jet-exit region. Theoretical ideas are tested by decomposing the atmospheric flow into a high- and a low-frequency part and by analyzing four-dimensional variational data assimilation (4DVAR) reanalysis data of the Fronts and Atlantic Storm-Track Experiment (FASTEX) during February 1997 as well as reanalysis data for the end of December 1999.Regions where the low-frequency deformation magnitude is greater than the absolute value of the low-frequency vorticity are shown to correspond to regions where synoptic disturbances at the same level tend to be located. These regions in the upper troposphere are intrinsically related to the horizontal inhomogeneities of the low-frequency large-scale upper-tropospheric jet but cannot be detected by looking separately at the deformation or vorticity. Transitions from one such large-scale region to the next furthermore can be accompanied by a sudden change of the dilatation axes orientation: this combination defines a barotropic critical region (BtCR). Reasons why a BtCR is a specific place where barotropic development is likely to occur are exposed. Two very differently located BtCR regions in two apparently similar zonal-like weather regimes are shown to be the preferred regions where synoptic eddies tend to cross the jet from the south to the north.BtCRs are also special regions where constructive association between barotropic and baroclinic processes is favored, indeed constrained to cooperate. This is illustrated through the detailed analysis of the last growth stage of Intensive Observation Period 17 (IOP17) of FASTEX. It happens precisely around a BtCR area located in the jet-exit region. Two processes explain this IOP17 development; one involves the barotropic

  9. Association of Myopic Optic Disc Deformation with Visual Field Defects in Paired Eyes with Open-Angle Glaucoma: A Cross-Sectional Study

    PubMed Central

    Sawada, Yu; Hangai, Masanori; Ishikawa, Makoto; Yoshitomi, Takeshi

    2016-01-01

    Purpose To examine the association of myopia with the visual field (VF) defects in open-angle glaucoma (OAG) using paired eyes to eliminate the effect of unknown confounding factors that are diverse among individuals. Methods One hundred eighteen eyes of 59 subjects with myopia (spherical equivalent [SE] ≥ -2 diopter [D] and axial length ≥ 24.0 mm) whose intra-ocular pressure between paired eyes was similar and the mean deviation (MD) of the Humphrey VF test differed by more than 6 dB were included. Refractive errors (SE, axial length) and parameters associated with the papillary and parapapillary myopic deformation (tilt ratio, torsion angle, and β-zone parapapillary atrophy [PPA] area without Bruch’s membrane) were measured in each eye. The paired eyes were divided into worse and better eyes according to the MD of the VF, and parameters were compared between them. Further, multiple linear regression analysis was performed to examine the correlation of the difference in various parameters with the MD difference between paired eyes. Results The SE of all eyes was -6.39 ± 2.15 D (mean ± standard deviation) and axial length was 26.42 ± 1.07 mm. MD of the worse and better VF eyes were -13.56 ± 6.65 dB and -4.87 ± 5.32 dB, respectively. Eyes with worse VFs had significantly greater SE, axial length, tilt ratio, and PPA area without Bruch’s membrane than those with better VFs (all P < 0.05). In multiple linear regression analysis, the difference of the MD between paired eyes was significantly correlated with the difference in the tilt ratio and PPA area without Bruch’s membrane. Conclusion The myopic papillary and parapapillary deformations, but not refractive error itself, were related to the worse VF in paired eyes with OAG. This suggests that myopia influences the severity of the glaucomatous VF defects via structural deformation. PMID:27571303

  10. Coseismic Deformation Field and Source Modelling for the August 24, 2016 Amatrice Event from the Inversion of InSAR and GPS Data

    NASA Astrophysics Data System (ADS)

    Salvi, S.; Cheloni, D.; Pezzo, G.; Tolomei, C.; Bignami, C.; Atzori, S.; Antonioli, A.; Trasatti, E.; Stramondo, S.; Devoti, R.; Riguzzi, F.; Serpelloni, E.; Pietrantonio, G.; Anzidei, M.; D'Agostino, N.; Avallone, A.; Cecere, G.; Esposito, A.; Sepe, V.; Galvani, A.; Selvaggi, G.; Giuliani, R.; Mattone, M.; Calcaterra, S.; Gambino, P.

    2016-12-01

    On August 24, 2016 a Mw 6.0 earthquake struck the Central Apennines, between the towns of Norcia and Amatrice. The epicentre was located near the village of Accumoli. Twenty hours later the first SAR interferogram was obtained from ALOS-2 data and clearly showed the co-seismic deformation field. In the following days, the InSAR analysis benefited from further data, also from Sentinel-1A and B, and COSMO-SkyMed. All displacement maps showed very similar patterns, with maximum displacement values of 20 cm away from the satellites. We will present the co-seismic deformation measurements and the source model obtained by inverting InSAR and GPS data ( 100 continuous and survey-mode GPS measurements). According to the two-lobe pattern, we modeled the data with two independent fault segments, coming up with very similar geometries and mechanisms. This suggests that the rupture occurred on a single structure, oriented NNW-SSE, dipping W at 45°-55°, extending about 18 km between the towns of Norcia and Amatrice. The slip distribution shows a 1.4 maximum in the north, at 5 km depth, and another large slip concentration ( 1m) in the south at 3 km depth, with an overall "geodetic" magnitude 6.2. We also computed the Coulomb Failure Function (CFF) on six nearby faults, obtained from the DISS Working Group, 2010, database. An increase of the CFF is only visible on two fault planes aligned with the Amatrice fault. These results were repeatedly updated during the emergency, as the new data became available. The information was then summarized in synthetic reports and disseminated to the Italian Civil Protection to support the decision making process. This result was obtained thanks to the free and fast data access procedures made available by initiatives as the CEOS Seismic Pilot, the ALOS 2 scientific AO, the EU Copernicus program.

  11. Finite element modelling of stress field perturbations and interseismic crustal deformation in the Val d'Agri region, southern Apennines, Italy

    NASA Astrophysics Data System (ADS)

    Candela, Stefania; Mazzoli, Stefano; Megna, Antonella; Santini, Stefano

    2015-08-01

    The Val d'Agri area provides the opportunity to analyse active structures in a seismic region for which a large amount of subsurface data is available. This area, which was struck in 1857 by one of the most destructive earthquakes in Italy (MW = 7.03), represents a unique natural laboratory to gain new insights into geometry, modes and rates of faulting controlling crustal deformation in an actively extending orogen. In this study, a crustal geological section through the southern Apennines is discretized into a finite element model (FEM). We present a 2D elastoplastic FEM that reproduces stress perturbations and strain field around the Val d'Agri active fault system. The influence of fault strand activity on interseismic crustal deformation is tested by a series of computer models, whose predictions are compared with the horizontal velocity components of continuous GPS sites in the region and with stress directions and geological data. The best fit with available geological and geophysical constraints is obtained with a 300 km long, 29 km deep model formed by a multilayer including three components having different rheological characteristics and including several shallow, locked fault segments, which branch into a freely slipping major basement fault at depth. Finite element modelling provides new insights into the controversial and widely debated active tectonic setting of the study area, pointing out the fundamental role played by a structural reactivation process involving inherited, long-lived, mature fault systems at depth. Our FEM, reconciling apparently contrasting geological and geophysical constraints from the study area, points to maximum stress build up and strain accumulation at a depth of 15 ± 5 km. Such a depth range is suggested as the most likely one for the nucleation of large events such as the 1857 Val d'Agri earthquake.

  12. Elastic line deformed on a surface by an external field: Intrinsic formulation and preliminary application to nucleosome energetics

    SciTech Connect

    Manning, G.S.

    1988-09-15

    If an elastically resilient thin rod (elastic line) is subjected to a static force field, it adopts a trajectory that minimizes the sum of its elastic energy and its energy of interaction with the field. Using ''intrinsic'' methods of differential geometry and variational calculus, we formulate and solve this problem for an elastic line confined to a general surface. The biological structure known as the nucleosome core particle provides motivation to apply the solution to an elastic line (DNA) subject to a centrosymmetric force emanating from a circle. In this case the surface is a plane (although the surface will be curved in a more accurate model). In preliminary numerical work we are able to represent the angular deviation of the elastic line to fifth order in powers of arc length. The result of greatest interest may be that the equilibrium trajectory appears not to approach the circle progressively with increasing strength of the attraction between line and circle. Instead, the line approaches a ''barrier'' trajectory and, as it does, becomes unstable relative to the circular arc.

  13. History matching and parameter estimation of surface deformation data for a CO2 sequestration field project using ensemble-based algorithm

    NASA Astrophysics Data System (ADS)

    Ping, J.; Tavakoli, R.; Min, B.; Srinivasan, S.; Wheeler, M. F.

    2015-12-01

    Optimal management of subsurface processes requires the characterization of the uncertainty in reservoir description and reservoir performance prediction. The application of ensemble-based algorithms for history matching reservoir models has been steadily increasing over the past decade. However, the majority of implementations in the reservoir engineering have dealt only with production history matching. During geologic sequestration, the injection of large quantities of CO2 into the subsurface may alter the stress/strain field which in turn can lead to surface uplift or subsidence. Therefore, it is essential to couple multiphase flow and geomechanical response in order to predict and quantify the uncertainty of CO2 plume movement for long-term, large-scale CO2 sequestration projects. In this work, we simulate and estimate the properties of a reservoir that is being used to store CO2 as part of the In Salah Capture and Storage project in Algeria. The CO2 is separated from produced natural gas and is re-injected into downdip aquifer portion of the field from three long horizontal wells. The field observation data includes ground surface deformations (uplift) measured using satellite-based radar (InSAR), injection well locations and CO2 injection rate histories provided by the operators. We implement ensemble-based algorithms for assimilating both injection rate data as well as geomechanical observations (surface uplift) into reservoir model. The preliminary estimation results of horizontal permeability and material properties such as Young Modulus and Poisson Ratio are consistent with available measurements and previous studies in this field. Moreover, the existence of high-permeability channels/fractures within the reservoir; especially in the regions around the injection wells are confirmed. This estimation results can be used to accurately and efficiently predict and monitor the movement of CO2 plume.

  14. The role of extensional viscosity in frog tongue projection

    NASA Astrophysics Data System (ADS)

    Noel, Alexis; Wagner, Caroline; McKinley, Gareth; Mendelson, Joe; Hu, David

    2014-11-01

    Frogs and other amphibians capture insects through high-speed tongue projection, some achieving tongue accelerations of over fifty times gravity. In this experimental study, we investigate how a frog's sticky saliva enables high-speed prey capture. At the Atlanta zoo, we used high-speed video to film the trajectory of frog tongues during prey capture. We have also designed and built a portable extensional rheometer; by following the capillary-driven thinning in the diameter of a thread of saliva we characterize the relaxation time and extensional viscosity and so infer the adhesive force between the frog tongue and prey.

  15. Field-induced expansion deformation in Pb islands on Cu(111): evidence from energy shift of empty quantum-well states.

    PubMed

    Chan, W Y; Huang, H S; Su, W B; Lin, W H; Jeng, H-T; Wu, M K; Chang, C S

    2012-04-06

    We use scanning tunneling microscopy and spectroscopy to measure the energy shift of empty quantum-well (QW) states in Pb islands on the Cu(111) surface. It is found that, with an increase of the electric field, the behavior of the energy shift can be grouped into two different modes for most QW states. In the first mode, the state energy moves toward high energy monotonically. In the second mode, the state energy shifts to a lower energy initially and then turns around to a higher energy. Moreover, we have observed that the QW states of higher energy behave in preference to the first mode, but they gradually change to the second mode as the Pb island becomes thicker. This thickness-dependent behavior reflects the existence of local expansion in the Pb islands, due to the electric field, and that the expansion is larger for a thicker island. QW states can thus be used for studying the localized lattice deformation in the nanometer scale.

  16. Microstructure study of a severely plastically deformed Mg-Zn-Y alloy by application of low angle annular dark field diffraction contrast imaging

    PubMed Central

    Basha, Dudekula Althaf; Rosalie, Julian M.; Somekawa, Hidetoshi; Miyawaki, Takashi; Singh, Alok; Tsuchiya, Koichi

    2016-01-01

    Microstructural investigation of extremely strained samples, such as severely plastically deformed (SPD) materials, by using conventional transmission electron microscopy techniques is very challenging due to strong image contrast resulting from the high defect density. In this study, low angle annular dark field (LAADF) imaging mode of scanning transmission electron microscope (STEM) has been applied to study the microstructure of a Mg-3Zn-0.5Y (at%) alloy processed by high pressure torsion (HPT). LAADF imaging advantages for observation of twinning, grain fragmentation, nucleation of recrystallized grains and precipitation on second phase particles in the alloy processed by HPT are highlighted. By using STEM-LAADF imaging with a range of incident angles, various microstructural features have been imaged, such as nanoscale subgrain structure and recrystallization nucleation even from the thicker region of the highly strained matrix. It is shown that nucleation of recrystallized grains starts at a strain level of revolution N=1/4 (earlier than detected by conventional bright field imaging). Occurrence of recrystallization of grains by nucleating heterogeneously on quasicrystalline particles is also confirmed. Minimizing all strain effects by LAADF imaging facilitated grain size measurement of 150±25 nm in fully recrystallized HPT specimen after N=5. PMID:27877863

  17. Quaternary deformation

    SciTech Connect

    Brown, R.D. Jr.

    1990-01-01

    Displaced or deformed rock units and landforms record the past 2 m.y. of faulting, folding, uplift, and subsidence in California. Properly interpreted, such evidence provides a quantitative basis for predicting future earthquake activity and for relating many diverse structures and landforms to the 5 cm/yr of horizontal motion at the boundary between the North American and Pacific plates. Modern techniques of geologic dating and expanded research on earthquake hazards have greatly improved our knowledge of the San Andreas fault system. Much of this new knowledge has been gained since 1965, and that part which concerns crustal deformation during the past 2 m.y. is briefly summarized here.

  18. Accessory pathway for sound transfer in a neotropical frog.

    PubMed Central

    Narins, P M; Ehret, G; Tautz, J

    1988-01-01

    A portion of the lateral body wall overlying the lung cavity of the arboreal frog, Eleutherodactylus coqui, vibrates in response to free-field sound. Peak displacement amplitude of the body wall in response to a natural call note presented at 73 decibels sound pressure level is 1.70 X 10(-9) m, roughly 8 decibels less than that of the ipsilateral eardrum, as measured by laser Doppler vibrometry. We show that the vibration magnitude varies predictably across the body profile and is posture and frequency dependent. Two routes to the inner ear are described for sounds impinging on the body wall; either of these accessory pathways could modify direct input from the peripheral auditory system and enhance sound localization in these small vertebrates. PMID:3422747

  19. Predator-prey relationships among larval dragonflies, salamanders, and frogs.

    PubMed

    Caldwell, J P; Thorp, J H; Jervey, T O

    1980-09-01

    Tadpoles of the barking tree frog, Hyla gratiosa, are abundant in spring and summer in some ponds and Carolina bays on the Savannah River Plant near Aiken, South Carolina. To determine how these tadpoles survive in the presence of predaceous salamander larvae, Ambystoma talpoideum, and larvae of an aeshnid dragonfly, Anax junius, we determined fields densities and sizes of the predators and the prey and conducted predation experiments in the laboratory. Tadpoles rapidly grow to a size not captured by Ambystoma, although Anax larvae can capture slightly larger tadpoles. Differing habitat preferences among the tadpoles and the two predator species probably aid in reducing predation pressure. Preliminary work indicates that the tadpoles may have an immobility response to an attack by a predator. In addition, the smallest, most vulnerable tadpoles have a distinctive color pattern which may function to disrupt the body outline and make them indiscernable to predators.

  20. Theory and simulation of the dynamics, deformation, and breakup of a chain of superparamagnetic beads under a rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Vázquez-Quesada, A.; Franke, T.; Ellero, M.

    2017-03-01

    In this work, an analytical model for the behavior of superparamagnetic chains under the effect of a rotating magnetic field is presented. It is postulated that the relevant mechanisms for describing the shape and breakup of the chains into smaller fragments are the induced dipole-dipole magnetic force on the external beads, their translational and rotational drag forces, and the tangential lubrication between particles. Under this assumption, the characteristic S-shape of the chain can be qualitatively understood. Furthermore, based on a straight chain approximation, a novel analytical expression for the critical frequency for the chain breakup is obtained. In order to validate the model, the analytical expressions are compared with full three-dimensional smoothed particle hydrodynamics simulations of magnetic beads showing excellent agreement. Comparison with previous theoretical results and experimental data is also reported.

  1. Three-dimensional displacement fields measured in a deforming granular-media surface by combined fringe projection and speckle photography

    NASA Astrophysics Data System (ADS)

    Barrientos, B.; Cerca, M.; García-Márquez, J.; Hernández-Bernal, C.

    2008-10-01

    3D displacement fields on a diffuse surface are measured by a combination of two optical methods, fringe projection and speckle photography. The use of a single camera for recording information from the two methods implies that no calibration procedures are necessary, as is the case in stereoscopy-based techniques. Out-of-plane displacements are measured by fringe projection whereas speckle photography yields the 2D in-plane component. By using this technique, we analyze in detail the morphological spatial-temporal evolution of an analogue model of the Earth's crust while subjected to compression forces. We discuss the experimental results and their relevance to the micromechanics of a surface of dry, non-cohesive and dilatant granular media. The results show that the combination of fringe projection and speckle photography is well suited for this type of study and allows the characterization of strain at the grain scale.

  2. Large scale 3D geometry of deformation structures in the Aar massif and overlying Helvetic nappes (Central Alps, Switzerland) - A combined remote sensing and field work approach

    NASA Astrophysics Data System (ADS)

    Baumberger, R.; Wehrens, Ph.; Herwegh, M.

    2012-04-01

    Allowing deep insight into the formation history of a rock complex, shear zones, faults and joint systems represent important sources of geological information. The granitic rocks of the Haslital valley (Switzerland) show very good outcrop conditions to study these mechanical anisotropies. Furthermore, they permit a quantitative characterisation of the above-mentioned deformation structures on the large-scale, in terms of their 3D orientation, 3D spatial distribution, kinematics and evolution in 3D. A key problem while developing valid geological 3D models is the three-dimensional spatial distribution of geological structures, particularly with increasing distance from the surface. That is especially true in regions, where only little or even no "hard" underground data (e.g. bore holes, tunnel mappings and seismics) is available. In the study area, many subsurface data are available (e.g. cross sections, tunnel and pipeline mappings, bore holes etc.). Therefore, two methods dealing with the problems mentioned are developed: (1) A data acquisition, processing and visualisation method, (2) A methodology to improve the reliability of 3D models regarding the spatial trend of geological structures with increasing depth: 1) Using aerial photographs and a high-resolution digital elevation model, a GIS-based remote-sensing structural map of large-scale structural elements (shear zones, faults) of the study area was elaborated. Based on that lineament map, (i) a shear zone map was derived and (ii) a geostatistical analysis was applied to identify sub regions applicable for serving as field areas to test the methodology presented above. During fieldwork, the shear zone map was evaluated by verifying the occurrence and spatial distribution of the structures designated by remote sensing. Additionally, the geometry of the structures (e.g. 3D orientation, width, kinematics) was characterised and parameterised accordingly. These tasks were partially done using a GPS based Slate

  3. Tolerance of fungal infection in European water frogs exposed to Batrachochytrium dendrobatidis after experimental reduction of innate immune defenses

    PubMed Central

    2012-01-01

    Background While emerging diseases are affecting many populations of amphibians, some populations are resistant. Determining the relative contributions of factors influencing disease resistance is critical for effective conservation management. Innate immune defenses in amphibian skin are vital host factors against a number of emerging pathogens such as ranaviruses and the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). Adult water frogs from Switzerland (Pelophylax esculentus and P. lessonae) collected in the field with their natural microbiota intact were exposed to Bd after experimental reduction of microbiota, skin peptides, both, or neither to determine the relative contributions of these defenses. Results Naturally-acquired Bd infections were detected in 10/51 P. lessonae and 4/19 P. esculentus, but no disease outbreaks or population declines have been detected at this site. Thus, this population was immunologically primed, and disease resistant. No mortality occurred during the 64 day experiment. Forty percent of initially uninfected frogs became sub-clinically infected upon experimental exposure to Bd. Reduction of both skin peptide and microbiota immune defenses caused frogs to gain less mass when exposed to Bd than frogs in other treatments. Microbiota-reduced frogs increased peptide production upon Bd infection. Ranavirus was undetectable in all but two frogs that appeared healthy in the field, but died within a week under laboratory conditions. Virus was detectable in both toe-clips and internal organs. Conclusion Intact skin microbiota reduced immune activation and can minimize subclinical costs of infection. Tolerance of Bd or ranavirus infection may differ with ecological conditions. PMID:23088169

  4. Deformation mechanisms in experimentally deformed Boom Clay

    NASA Astrophysics Data System (ADS)

    Desbois, Guillaume; Schuck, Bernhard; Urai, Janos

    2016-04-01

    Bulk mechanical and transport properties of reference claystones for deep disposal of radioactive waste have been investigated since many years but little is known about microscale deformation mechanisms because accessing the relevant microstructure in these soft, very fine-grained, low permeable and low porous materials remains difficult. Recent development of ion beam polishing methods to prepare high quality damage free surfaces for scanning electron microscope (SEM) is opening new fields of microstructural investigation in claystones towards a better understanding of the deformation behavior transitional between rocks and soils. We present results of Boom Clay deformed in a triaxial cell in a consolidated - undrained test at a confining pressure of 0.375 MPa (i.e. close to natural value), with σ1 perpendicular to the bedding. Experiments stopped at 20 % strain. As a first approximation, the plasticity of the sample can be described by a Mohr-Coulomb type failure envelope with a coefficient of cohesion C = 0.117 MPa and an internal friction angle ϕ = 18.7°. After deformation test, the bulk sample shows a shear zone at an angle of about 35° from the vertical with an offset of about 5 mm. We used the "Lamipeel" method that allows producing a permanent absolutely plane and large size etched micro relief-replica in order to localize and to document the shear zone at the scale of the deformed core. High-resolution imaging of microstructures was mostly done by using the BIB-SEM method on key-regions identified after the "Lamipeel" method. Detailed BIB-SEM investigations of shear zones show the following: the boundaries between the shear zone and the host rock are sharp, clay aggregates and clastic grains are strongly reoriented parallel to the shear direction, and the porosity is significantly reduced in the shear zone and the grain size is smaller in the shear zone than in the host rock but there is no evidence for broken grains. Comparison of microstructures

  5. Neuromuscular control of prey capture in frogs.

    PubMed Central

    Nishikawa, K C

    1999-01-01

    While retaining a feeding apparatus that is surprisingly conservative morphologically, frogs as a group exhibit great variability in the biomechanics of tongue protraction during prey capture, which in turn is related to differences in neuromuscular control. In this paper, I address the following three questions. (1) How do frog tongues differ biomechanically? (2) What anatomical and physiological differences are responsible? (3) How is biomechanics related to mechanisms of neuromuscular control? Frog species use three non-exclusive mechanisms to protract their tongues during feeding: (i) mechanical pulling, in which the tongue shortens as its muscles contract during protraction; (ii) inertial elongation, in which the tongue lengthens under inertial and muscular loading; and (iii) hydrostatic elongation, in which the tongue lengthens under constraints imposed by the constant volume of a muscular hydrostat. Major differences among these functional types include (i) the amount and orientation of collagen fibres associated with the tongue muscles and the mechanical properties that this connective tissue confers to the tongue as a whole; and (ii) the transfer of intertia from the opening jaws to the tongue, which probably involves a catch mechanism that increases the acceleration achieved during mouth opening. The mechanisms of tongue protraction differ in the types of neural mechanisms that are used to control tongue movements, particularly in the relative importance of feed-forward versus feedback control, in requirements for precise interjoint coordination, in the size and number of motor units, and in the afferent pathways that are involved in coordinating tongue and jaw movements. Evolution of biomechanics and neuromuscular control of frog tongues provides an example in which neuromuscular control is finely tuned to the biomechanical constraints and opportunities provided by differences in morphological design among species. PMID:10382226

  6. CHARACTERISTICS OF FROG CARCINOMA IN TISSUE CULTURE.

    PubMed

    Lucké, B

    1939-08-31

    The adenocarcinoma of leopard frogs may be cultivated with ease in plasma media. In such cultures two types of growth occur with regularity. The first is in the form of tubules which promptly grow out in the solid medium and retain their tubular form as long as they remain completely enveloped by plasma. When, however, they make contact with the surface of the glass, they adhere to it, the part in contact becomes flat, and its cells now grow no longer as tubules but as membranes. The manner of growth in vitro resembles the growth of transplants of the same tumor in the anterior chamber of the living eye, thus suggesting that in each case the habit of growth is determined by the same morphogenetic factors, i.e. those inherent in the cells themselves, and those depending on interfacial forces. The malignant cells of the frog carcinoma have the attributes which in general distinguish malignant cells from normal cells of corresponding type. In comparison with adult kidney cells, their normal homologues, the conspicuous properties of frog carcinoma cells are: larger and more variable size and shape of cell body, of nucleus, and nucleolus; coarser and denser structure of cytoplasm, of nucleoplasm, and of nuclear membrane; increase in number of mitochondria, and more frequent occurrence of mitosis. These cytological characteristics remain unaltered in cultures maintained for as long as six months. Frog carcinoma is a transmissible disease due to an agent which induces inclusion bodies, and which has other attributes indicating that it is a virus. The general correspondence in character between its cells and the malignant cells of mammalian tumors of diverse origin suggests that neoplastic phenomena are essentially alike, no matter in what group of animals they occur or what their causal factors may be.

  7. Yolk pigments of the Mexican leaf frog.

    PubMed

    Marinetti, G V; Bagnara, J T

    1983-02-25

    Eggs of the Mexican leaf frog contain blue and yellow pigments identified as biliverdin and lutein, respectively. Both pigments are bound to proteins that occur in crystalline form in the yolk platelet. The major blue pigment is biliverdin IX alpha. The eggs vary in color from brilliant blue to pale yellow-green depending on the amount of each pigment. These pigments may provide protective coloration to the eggs.

  8. ROCK DEFORMATION. Final Progress Report

    SciTech Connect

    2002-05-24

    The Gordon Research Conference (GRC) on ROCK DEFORMATION was held at II Ciocco from 5/19/02 thru 5/24/02. Emphasis was placed on current unpublished research and discussion of the future target areas in this field.

  9. Crustal deformation and earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1984-01-01

    The manner in which the Earth's surface deforms during the cycle of stress accumulation and release along major faults is investigated. In an investigation of the crustal deformation associated with a thin channel asthenosphere displacements are reduced from those computed for a half space asthenosphere. A previous finding by other workers that displacements are enhanced when flow is confined to a thin channel is based on several invalid approximations. The major predictions of the finite element model are that the near field postseismic displacements and strain rates are less than those for a half space asthenosphere and that the postseismic strain rates at intermediate distances are greater (in magnitude). The finite width of the asthenosphere ceases to have a significant impact on the crustal deformation pattern when its magnitude exceeds about three lithosphere thicknesses.

  10. Crustal deformation and earthquakes

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1984-01-01

    The manner in which the Earth's surface deforms during the cycle of stress accumulation and release along major faults is investigated. In an investigation of the crustal deformation associated with a thin channel asthenosphere displacements are reduced from those computed for a half space asthenosphere. A previous finding by other workers that displacements are enhanced when flow is confined to a thin channel is based on several invalid approximations. The major predictions of the finite element model are that the near field postseismic displacements and strain rates are less than those for a half space asthenosphere and that the postseismic strain rates at intermediate distances are greater (in magnitude). The finite width of the asthenosphere ceases to have a significant impact on the crustal deformation pattern when its magnitude exceeds about three lithosphere thicknesses.

  11. Neotectonic stress field of the south-eastern East European platform as related to the Late Alpine collision deformation of the Greater Caucasus

    NASA Astrophysics Data System (ADS)

    Kopp, Mikhail L.; Kolesnichenko, Aleksei; Vassiliev, Nikita; Mostryukov, Alexandre

    2013-04-01

    Greater Caucasian orogen built by an actived basement of the Scythyan plate. Signs of influence of collisional pressure onto intraplate deformations are also demonstrated by the Cenozoic stress/deformation field studied by the authors by means of mesotectonic measurements of tectonic striation, slickensides and veins in the Upper Mesozoic-Quaternary rocks. As a result, a series of maps of the Cenozoic stress field of the area studied has been first computered. The maps show an orientation and dip of general normal and tangential tectonic stresses as well as a character of a stress regime type (compression, extension, or horizontal shear) determined with the Lode-Nadai coefficient. A combination of the macrotectonic and mesotectonic data allows the following conclusions on dynamics of the platform neotectonic structures formation. (1) In the southern part of the studied platform area (the Zhigouli, Saratov and Kerensk-Chembar dislocations, and Donets coal basin in the Alpine stage), formation of the structures was greatly affected by increasing toward the Greater Caucasus compression in the thrust and strike-slip stress regimes. Horizontal projections of a compression axis in all these areas are oriented submeridionally (up to NE-SW) whereas horizontal projections of an extension axis are oriented sublatitudinally (up to WSW-ESE)). (2) The compression is also growing eastward, to the Uralian-Mougodjary recent orogen but its axis is directed there sublatitudinally, with the extension axis orienting submeridionally. (3) In the right angle between mutually perpendicular domains: the southern (adjacent to the Caucasus) and eastern ("the Uralian") ones, a domain of horizontal extension is present; its axis was oriented both sublatitudinally and submeridionally. In topography this area represents a vast depression, with its centre approximately marked by the point of a confluence of Kama with Volga, the greatest rivers of the Russian plain. There the collision (?) compression

  12. Benchmarking of depth of field for large out-of-plane deformations with single camera digital image correlation

    NASA Astrophysics Data System (ADS)

    Van Mieghem, Bart; Ivens, Jan; Van Bael, Albert

    2017-04-01

    A problem that arises when performing stereo digital image correlation in applications with large out-of-plane displacements is that the images may become unfocused. This unfocusing could result in correlation instabilities or inaccuracies. When performing DIC measurements and expecting large out-of-plane displacements researchers either trust on their experience or use the equations from photography to estimate the parameters affecting the depth of field (DOF) of the camera. A limitation of the latter approach is that the definition of sharpness is a human defined parameter and that it does not reflect the performance of the digital image correlation system. To get a more representative DOF value for DIC applications, a standardised testing method is presented here, making use of real camera and lens combinations as well as actual image correlation results. The method is based on experimental single camera DIC measurements of a backwards moving target. Correlation results from focused and unfocused images are compared and a threshold value defines whether or not the correlation results are acceptable even if the images are (slightly) unfocused. By following the proposed approach, the complete DOF of a specific camera/lens combination as function of the aperture setting and distance from the camera to the target can be defined. The comparison between the theoretical and the experimental DOF results shows that the achievable DOF for DIC applications is larger than what theoretical calculations predict. Practically this means that the cameras can be positioned closer to the target than what is expected from the theoretical approach. This leads to a gain in resolution and measurement accuracy.

  13. A Methodology to Validate the InSAR Derived Displacement Field of the September 7th, 1999 Athens Earthquake Using Terrestrial Surveying. Improvement of the Assessed Deformation Field by Interferometric Stacking

    PubMed Central

    Kotsis, Ioannis; Kontoes, Charalabos; Paradissis, Dimitrios; Karamitsos, Spyros; Elias, Panagiotis; Papoutsis, Ioannis

    2008-01-01

    The primary objective of this paper is the evaluation of the InSAR derived displacement field caused by the 07/09/1999 Athens earthquake, using as reference an external data source provided by terrestrial surveying along the Mornos river open aqueduct. To accomplish this, a processing chain to render comparable the leveling measurements and the interferometric derived measurements has been developed. The distinct steps proposed include a solution for reducing the orbital and atmospheric interferometric fringes and an innovative method to compute the actual InSAR estimated vertical ground subsidence, for direct comparison with the leveling data. Results indicate that the modeled deformation derived from a series of stacked interferograms, falls entirely within the confidence interval assessed for the terrestrial surveying data. PMID:27879926

  14. Effective theory for the nonrigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei

    DOE PAGES

    Coello Pérez, Eduardo A.; Papenbrock, Thomas F.

    2015-07-27

    In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoreticalmore » uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 02+ band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.« less

  15. Effective theory for the nonrigid rotor in an electromagnetic field: Toward accurate and precise calculations of E2 transitions in deformed nuclei

    SciTech Connect

    Coello Pérez, Eduardo A.; Papenbrock, Thomas F.

    2015-07-27

    In this paper, we present a model-independent approach to electric quadrupole transitions of deformed nuclei. Based on an effective theory for axially symmetric systems, the leading interactions with electromagnetic fields enter as minimal couplings to gauge potentials, while subleading corrections employ gauge-invariant nonminimal couplings. This approach yields transition operators that are consistent with the Hamiltonian, and the power counting of the effective theory provides us with theoretical uncertainty estimates. We successfully test the effective theory in homonuclear molecules that exhibit a large separation of scales. For ground-state band transitions of rotational nuclei, the effective theory describes data well within theoretical uncertainties at leading order. To probe the theory at subleading order, data with higher precision would be valuable. For transitional nuclei, next-to-leading-order calculations and the high-precision data are consistent within the theoretical uncertainty estimates. In addition, we study the faint interband transitions within the effective theory and focus on the E2 transitions from the 02+ band (the “β band”) to the ground-state band. Here the predictions from the effective theory are consistent with data for several nuclei, thereby proposing a solution to a long-standing challenge.

  16. Using a Phototransduction System to Monitor the Isolated Frog Heart

    ERIC Educational Resources Information Center

    Stephens, Philip J.

    2015-01-01

    A simple and inexpensive method of monitoring the movement of an isolated frog heart provides comparable results to those obtained with a force transducer. A commercially available photoresistor is integrated into a Wheatstone bridge circuit, and the output signal is interfaced directly with a recording device. An excised, beating frog heart is…

  17. Coleman Revisited: School Segregation, Peers, and Frog Ponds

    ERIC Educational Resources Information Center

    Goldsmith, Pat Rubio

    2011-01-01

    Students from minority segregated schools tend to achieve and attain less than similar students from White segregated schools. This study examines whether peer effects can explain this relationship using normative models and frog-pond models. Normative models (where peers become alike) suggest that minority schoolmates are a liability. Frog-pond…

  18. Using a Phototransduction System to Monitor the Isolated Frog Heart

    ERIC Educational Resources Information Center

    Stephens, Philip J.

    2015-01-01

    A simple and inexpensive method of monitoring the movement of an isolated frog heart provides comparable results to those obtained with a force transducer. A commercially available photoresistor is integrated into a Wheatstone bridge circuit, and the output signal is interfaced directly with a recording device. An excised, beating frog heart is…

  19. Coleman Revisited: School Segregation, Peers, and Frog Ponds

    ERIC Educational Resources Information Center

    Goldsmith, Pat Rubio

    2011-01-01

    Students from minority segregated schools tend to achieve and attain less than similar students from White segregated schools. This study examines whether peer effects can explain this relationship using normative models and frog-pond models. Normative models (where peers become alike) suggest that minority schoolmates are a liability. Frog-pond…

  20. Foothill yellow-legged frog conservation assessment in California

    Treesearch

    Marc P. Hayes; Clara A. Wheeler; Amy J. Lind; Gregory A. Green; Diane C. Macfarlane

    2016-01-01

    The foothill yellow-legged frog (Rana boylii) is a stream-breeding amphibian that has experienced significant population declines over a large portion of its historical range. This frog is nearing extirpation in much of the Sierra Nevada region where existing populations are sparse. Water development and diversions are likely to be the primary...