The Experts below are selected from a list of 270 Experts worldwide ranked by ideXlab platform
Castrenze Polizzotto - One of the best experts on this subject based on the ideXlab platform.
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size effects of small scale beams in bending addressed with a Strain Difference based nonlocal elasticity theory
International Journal of Mechanical Sciences, 2019Co-Authors: P Fuschi, A.a. Pisano, Castrenze PolizzottoAbstract:Abstract A Strain-Difference based nonlocal elasticity model devised by the authors elsewhere (Polizzotto et al., Int. J. Solids Struct. 25 (2006) 308–333) is applied to small-scale homogeneous beam models in bending under static loads in the purpose to describe the inherent size effects. With this theory —belonging to the Strain-integral nonlocal model family, but exempt from anomalies typical of the Eringen nonlocal theory— the relevant beam problem is reduced to a set of three mutually independent Fredholm integral equations of the second kind (each independent of the beam’s ordinary boundary conditions, only one depends on the given load), which can be routinely solved numerically. Applications to five cases of beam samples (usually addressed in the literature) are performed, the obtained results are graphically illustrated and compared with analogous results from the literature. Size effects of stiffeningtype are found for all beam samples, in agreement with the analogous results obtained with the well-known and widely accepted Strain gradient elasticity model. Analogous size effects are expected to be predicted for other multi-dimensional structures, all of which seems to confirm the smaller-is-stifferphenomenon.
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a Strain Difference based nonlocal elasticity model
International Journal of Solids and Structures, 2004Co-Authors: Castrenze Polizzotto, P Fuschi, A.a. PisanoAbstract:Abstract A two-component local/nonlocal constitutive model for (macroscopically) inhomogeneous linear elastic materials (but constant internal length) is proposed, in which the stress is the sum of the local stress and a nonlocal-type stress expressed in terms of the Strain Difference field, hence identically vanishing in the case of uniform Strain. Attention is focused upon the particular case of piecewise homogeneous material. The proposed model is thermodynamically consistent with a suitable free energy potential. It constitutes an improved form of the Vermeer and Brinkgreve [A new effective nonlocal Strain measure for softening plasticity. In: Chambon, R., Desrues, J., Vardulakis, I. (Eds.), Localization and Bifurcation theory for Soils and Rocks. Balkema, Rotterdam, 1994, pp. 89–100] model, and can also be considered derivable from the Eringen nonlocal elasticity model through a suitable enhancement technique based on the concept of redistribution of the local stress. The concept of equivalent distance is introduced to macroscopically account for the further attenuation effects produced by the inhomogeneity upon the long distance interaction forces. With the aid of a piecewise homogeneous bar in tension, a portion of which degrades progressively till failure, it is shown that––under a suitable choice of a material constant––the solution procedure exhibits no pathological features (numerical instability, mesh sensitivity) in every degraded bar condition, including the limit idealized stress-free condition of the failed bar.
David C. Airey - One of the best experts on this subject based on the ideXlab platform.
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The serotonin 2C receptor potently modulates the head-twitch response in mice induced by a phenethylamine hallucinogen
Psychopharmacology, 2010Co-Authors: Clinton E Canal, Paul J Gresch, Uade B. Olaghere Da Silva, Elaine Sanders-bush, Erin E Watt, David C. AireyAbstract:Rationale Hallucinogenic serotonin 2A (5-HT_2A) receptor partial agonists, such as (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT_2A receptor antagonists. In addition to 5-HT_2A receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT_2C receptors. Objectives We tested for involvement of 5-HT_2C receptors in the HTR induced by DOI. Results Comparison of 5-HT_2C receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT_2C receptor antagonist SB206553 or SB242084 eradicated a twofold Difference in DOI-induced HTR between the standard inbred mouse Strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both Strains. None of several measures of 5-HT_2A receptors in frontal cortex explained the Strain Difference, including 5-HT_2A receptor density, Gα_q or Gα_i/o protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2 . 5-HT_2C receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT_2C receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the Strain Difference in response to DOI. Conclusions We conclude that the HTR to DOI in mice is strongly modulated by 5-HT_2C receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT_2 receptors.
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the serotonin 2c receptor potently modulates the head twitch response in mice induced by a phenethylamine hallucinogen
Psychopharmacology, 2010Co-Authors: Paul J Gresch, Elaine Sandersbush, Uade Olaghere B Da Silva, Clinton E Canal, Erin E Watt, David C. AireyAbstract:Hallucinogenic serotonin 2A (5-HT2A) receptor partial agonists, such as (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT2A receptor antagonists. In addition to 5-HT2A receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT2C receptors. We tested for involvement of 5-HT2C receptors in the HTR induced by DOI. Comparison of 5-HT2C receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT2C receptor antagonist SB206553 or SB242084 eradicated a twofold Difference in DOI-induced HTR between the standard inbred mouse Strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both Strains. None of several measures of 5-HT2A receptors in frontal cortex explained the Strain Difference, including 5-HT2A receptor density, Gαq or Gαi/o protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2. 5-HT2C receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT2C receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the Strain Difference in response to DOI. We conclude that the HTR to DOI in mice is strongly modulated by 5-HT2C receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT2 receptors.
Clinton E Canal - One of the best experts on this subject based on the ideXlab platform.
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The serotonin 2C receptor potently modulates the head-twitch response in mice induced by a phenethylamine hallucinogen
Psychopharmacology, 2010Co-Authors: Clinton E Canal, Paul J Gresch, Uade B. Olaghere Da Silva, Elaine Sanders-bush, Erin E Watt, David C. AireyAbstract:Rationale Hallucinogenic serotonin 2A (5-HT_2A) receptor partial agonists, such as (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT_2A receptor antagonists. In addition to 5-HT_2A receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT_2C receptors. Objectives We tested for involvement of 5-HT_2C receptors in the HTR induced by DOI. Results Comparison of 5-HT_2C receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT_2C receptor antagonist SB206553 or SB242084 eradicated a twofold Difference in DOI-induced HTR between the standard inbred mouse Strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both Strains. None of several measures of 5-HT_2A receptors in frontal cortex explained the Strain Difference, including 5-HT_2A receptor density, Gα_q or Gα_i/o protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2 . 5-HT_2C receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT_2C receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the Strain Difference in response to DOI. Conclusions We conclude that the HTR to DOI in mice is strongly modulated by 5-HT_2C receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT_2 receptors.
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the serotonin 2c receptor potently modulates the head twitch response in mice induced by a phenethylamine hallucinogen
Psychopharmacology, 2010Co-Authors: Paul J Gresch, Elaine Sandersbush, Uade Olaghere B Da Silva, Clinton E Canal, Erin E Watt, David C. AireyAbstract:Hallucinogenic serotonin 2A (5-HT2A) receptor partial agonists, such as (±)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane hydrochloride (DOI), induce a frontal cortex-dependent head-twitch response (HTR) in rodents, a behavioral proxy of a hallucinogenic response that is blocked by 5-HT2A receptor antagonists. In addition to 5-HT2A receptors, DOI and most other serotonin-like hallucinogens have high affinity and potency as partial agonists at 5-HT2C receptors. We tested for involvement of 5-HT2C receptors in the HTR induced by DOI. Comparison of 5-HT2C receptor knockout and wild-type littermates revealed an approximately 50% reduction in DOI-induced HTR in knockout mice. Also, pretreatment with either the 5-HT2C receptor antagonist SB206553 or SB242084 eradicated a twofold Difference in DOI-induced HTR between the standard inbred mouse Strains C57BL/6J and DBA/2J, and decreased the DOI-induced HTR by at least 50% in both Strains. None of several measures of 5-HT2A receptors in frontal cortex explained the Strain Difference, including 5-HT2A receptor density, Gαq or Gαi/o protein levels, phospholipase C activity, or DOI-induced expression of Egr1 and Egr2. 5-HT2C receptor density in the brains of C57BL/6J and DBA/2J was also equivalent, suggesting that 5-HT2C receptor-mediated intracellular signaling or other physiological modulators of the HTR may explain the Strain Difference in response to DOI. We conclude that the HTR to DOI in mice is strongly modulated by 5-HT2C receptor activity. This novel finding invites reassessment of hallucinogenic mechanisms involving 5-HT2 receptors.
A.a. Pisano - One of the best experts on this subject based on the ideXlab platform.
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size effects of small scale beams in bending addressed with a Strain Difference based nonlocal elasticity theory
International Journal of Mechanical Sciences, 2019Co-Authors: P Fuschi, A.a. Pisano, Castrenze PolizzottoAbstract:Abstract A Strain-Difference based nonlocal elasticity model devised by the authors elsewhere (Polizzotto et al., Int. J. Solids Struct. 25 (2006) 308–333) is applied to small-scale homogeneous beam models in bending under static loads in the purpose to describe the inherent size effects. With this theory —belonging to the Strain-integral nonlocal model family, but exempt from anomalies typical of the Eringen nonlocal theory— the relevant beam problem is reduced to a set of three mutually independent Fredholm integral equations of the second kind (each independent of the beam’s ordinary boundary conditions, only one depends on the given load), which can be routinely solved numerically. Applications to five cases of beam samples (usually addressed in the literature) are performed, the obtained results are graphically illustrated and compared with analogous results from the literature. Size effects of stiffeningtype are found for all beam samples, in agreement with the analogous results obtained with the well-known and widely accepted Strain gradient elasticity model. Analogous size effects are expected to be predicted for other multi-dimensional structures, all of which seems to confirm the smaller-is-stifferphenomenon.
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Plane stress problems in nonlocal elasticity: finite element solutions with a Strain-Difference-based formulation
Journal of Mathematical Analysis and Applications, 2015Co-Authors: Paolo Fuschi, A.a. Pisano, D. Di DomenicoAbstract:An enhanced computational version of the finite element method in the context of nonlocal Strain-integral elasticity of Eringen-type is discussed. The theoretical bases of the method are illustrated focusing the attention on numerical and computational aspects as well as on the construction of the nonlocal elements matrices. Two numerical examples of plane stress nonlocal elasticity are presented to show the potentials and the limits of the promoted approach.
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a Strain Difference based nonlocal elasticity model
International Journal of Solids and Structures, 2004Co-Authors: Castrenze Polizzotto, P Fuschi, A.a. PisanoAbstract:Abstract A two-component local/nonlocal constitutive model for (macroscopically) inhomogeneous linear elastic materials (but constant internal length) is proposed, in which the stress is the sum of the local stress and a nonlocal-type stress expressed in terms of the Strain Difference field, hence identically vanishing in the case of uniform Strain. Attention is focused upon the particular case of piecewise homogeneous material. The proposed model is thermodynamically consistent with a suitable free energy potential. It constitutes an improved form of the Vermeer and Brinkgreve [A new effective nonlocal Strain measure for softening plasticity. In: Chambon, R., Desrues, J., Vardulakis, I. (Eds.), Localization and Bifurcation theory for Soils and Rocks. Balkema, Rotterdam, 1994, pp. 89–100] model, and can also be considered derivable from the Eringen nonlocal elasticity model through a suitable enhancement technique based on the concept of redistribution of the local stress. The concept of equivalent distance is introduced to macroscopically account for the further attenuation effects produced by the inhomogeneity upon the long distance interaction forces. With the aid of a piecewise homogeneous bar in tension, a portion of which degrades progressively till failure, it is shown that––under a suitable choice of a material constant––the solution procedure exhibits no pathological features (numerical instability, mesh sensitivity) in every degraded bar condition, including the limit idealized stress-free condition of the failed bar.
P Fuschi - One of the best experts on this subject based on the ideXlab platform.
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size effects of small scale beams in bending addressed with a Strain Difference based nonlocal elasticity theory
International Journal of Mechanical Sciences, 2019Co-Authors: P Fuschi, A.a. Pisano, Castrenze PolizzottoAbstract:Abstract A Strain-Difference based nonlocal elasticity model devised by the authors elsewhere (Polizzotto et al., Int. J. Solids Struct. 25 (2006) 308–333) is applied to small-scale homogeneous beam models in bending under static loads in the purpose to describe the inherent size effects. With this theory —belonging to the Strain-integral nonlocal model family, but exempt from anomalies typical of the Eringen nonlocal theory— the relevant beam problem is reduced to a set of three mutually independent Fredholm integral equations of the second kind (each independent of the beam’s ordinary boundary conditions, only one depends on the given load), which can be routinely solved numerically. Applications to five cases of beam samples (usually addressed in the literature) are performed, the obtained results are graphically illustrated and compared with analogous results from the literature. Size effects of stiffeningtype are found for all beam samples, in agreement with the analogous results obtained with the well-known and widely accepted Strain gradient elasticity model. Analogous size effects are expected to be predicted for other multi-dimensional structures, all of which seems to confirm the smaller-is-stifferphenomenon.
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a Strain Difference based nonlocal elasticity model
International Journal of Solids and Structures, 2004Co-Authors: Castrenze Polizzotto, P Fuschi, A.a. PisanoAbstract:Abstract A two-component local/nonlocal constitutive model for (macroscopically) inhomogeneous linear elastic materials (but constant internal length) is proposed, in which the stress is the sum of the local stress and a nonlocal-type stress expressed in terms of the Strain Difference field, hence identically vanishing in the case of uniform Strain. Attention is focused upon the particular case of piecewise homogeneous material. The proposed model is thermodynamically consistent with a suitable free energy potential. It constitutes an improved form of the Vermeer and Brinkgreve [A new effective nonlocal Strain measure for softening plasticity. In: Chambon, R., Desrues, J., Vardulakis, I. (Eds.), Localization and Bifurcation theory for Soils and Rocks. Balkema, Rotterdam, 1994, pp. 89–100] model, and can also be considered derivable from the Eringen nonlocal elasticity model through a suitable enhancement technique based on the concept of redistribution of the local stress. The concept of equivalent distance is introduced to macroscopically account for the further attenuation effects produced by the inhomogeneity upon the long distance interaction forces. With the aid of a piecewise homogeneous bar in tension, a portion of which degrades progressively till failure, it is shown that––under a suitable choice of a material constant––the solution procedure exhibits no pathological features (numerical instability, mesh sensitivity) in every degraded bar condition, including the limit idealized stress-free condition of the failed bar.
