Comparative seismic performance of a moment frame equipped with Lateral Impact Resilient Double Concave Frictional devices

This study presents a comparative assessment of the seismic performance of a reinforced concrete moment frame equipped with a new isolator. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has an enhanced inner slider capable of limiting the magnitude of the lateral impact force generated between the inner slider and the restraining rims of the sliding surfaces. Due to the presence of a plane high-friction interface with an internal gap, the novel isolator has an increased energy dissipation capacity that is activated during the lateral impact. Three isolation systems were considered to evaluate the benefits of using LIR-DCFP devices. One conformed by the suggested isolator, and two composed of classic non-articulated Double Concave Friction Pendulum (DCFP) bearings. The isolation devices were modelled employing a numerical formulation based on rigid body dynamics, capable of accounting for the lateral impact behaviour. The superstructure, a reinforced concrete moment resisting frame designed according to the American ASCE/SEI 7-16 standard, was modelled using beam-column elements considering geometric and material nonlinearities. Furthermore, the degrading behaviour of the building was incorporated using a proper degradation model for both the stiffness and the force. Incremental Dynamic Analyses (IDAs) were performed considering the friction coefficient as a random variable to characterize the statistics of the maximum inter-story responses. With the data generated in the IDAs, fragility curves related to the superstructure performance were constructed. Finally, employing the hazard curve, reliability curves were derived. The superstructure equipped with LIR-DCFP bearings presents better seismic performance than the same building equipped with the same size DCFP isolators. The benefits of using the new isolator are not achieved by increasing the lateral capacity of the classic isolation system

Thermal neutral format based on the step technology

The exchange of models is one of the most serious problems currently encountered in the practice of spacecraft thermal analysis. Essentially, the problem originates in the diversity of computing environments that are used across different sites, and the consequent proliferation of native tool formats. Furthermore, increasing pressure to reduce the development's life cycle time has originated a growing interest in the so-called spacecraft concurrent engineering. In this context, the realization of the interdependencies between different disciplines and the proper communication between them become critical issues. The use of a neutral format represents a step forward in addressing these problems. Such a means of communication is adopted by consensus. A neutral format is not directly tied to any specific tool and it is kept under stringent change control. Currently, most of the groups promoting exchange formats are contributing with their experience to STEP, the Standard for Exchange of Product Model Data, which is being developed under the auspices of the International Standards Organization (ISO 10303). This paper presents the different efforts made in Europe to provide the spacecraft thermal analysis community with a Thermal Neutral Format (TNF) based on STEP. Following an introduction with some background information, the paper presents the characteristics of the STEP standard. Later, the first efforts to produce a STEP Spacecraft Thermal Application Protocol are described. Finally, the paper presents the currently harmonized European activities that follow up and extend earlier work on the area

STATIC AND DYNAMIC EXPERIMENTAL VALIDATIONS OF THE LATERAL IMPACT RESILIENT DOUBLE CONCAVE FRICTION PENDULUM (LIR-DCFP) BEARING

During high-magnitude earthquakes, large base displacements that exceed the lateral capacity of the isolation level can cause internal impacts jeopardizing the benefits of using seismic isolation. The Lateral Impact Resilient Double Concave Friction Pendulum (LIR-DCFP) bearing has been proposed to mitigate the adverse effects of internal lateral impacts between inner sliders and restraining rims of sliding surfaces. This device has an enhanced inner slider formed by two bodies. These bodies are in contact, generating a plane high-friction interface capable of dissipating additional energy and limiting the magnitude of the impact. A numerical model based on rigid body dynamics has been proposed to represent the dynamic response of structures equipped with LIR-DCFP bearings. The numerical formulation includes important modeling aspects such as lateral impact behavior and large displacements (P-? effects), among other essential phenomena. A prototype of this novel device was constructed to validate its lateral behavior through static experimental tests. As predicted, if the inner slider does not contact the restraining rims of the sliding surfaces, the response of the isolator will be identical to the response of the classical frictional isolators. On the contrary, for larger lateral displacements, the contact between the inner slider and the restraining rims triggers high friction sliding. Finally, experimental tests were conducted to validate the dynamic response of a stiff structure equipped with four LIR-DCFP devices. An accurate prediction of the dynamic response can be obtained by employing the suggested numerical model under the presence or absence of internal lateral impacts

Dominant negative phenotype of Bacillus thuringiensis Cry1Ab, Cry11Aa and Cry4Ba mutants suggest hetero-oligomer formation among different Cry toxins.

Background - Bacillus thuringiensis Cry toxins are used worldwide in the control of different insect pests important in agriculture or in human health. The Cry proteins are pore-forming toxins that affect the midgut cell of target insects. It was shown that non-toxic Cry1Ab helix a-4 mutants had a dominant negative (DN) phenotype inhibiting the toxicity of wildtype Cry1Ab when used in equimolar or sub-stoichiometric ratios (1:1, 0.5:1, mutant:wt) indicating that oligomer formation is a key step in toxicity of Cry toxins. Methodology/Principal Findings - The DN Cry1Ab-D136N/T143D mutant that is able to block toxicity of Cry1Ab toxin, was used to analyze its capacity to block the activity against Manduca sexta larvae of other Cry1 toxins, such as Cry1Aa, Cry1Ac, Cry1Ca, Cry1Da, Cry1Ea and Cry1Fa. Cry1Ab-DN mutant inhibited toxicity of Cry1Aa, Cry1Ac and Cry1Fa. In addition, we isolated mutants in helix a-4 of Cry4Ba and Cry11Aa, and demonstrate that Cry4Ba-E159K and Cry11Aa-V142D are inactive and completely block the toxicity against Aedes aegypti of both wildtype toxins, when used at sub-stoichiometric ratios, confirming a DN phenotype. As controls we analyzed Cry1Ab-R99A or Cry11Aa-E97A mutants that are located in helix a-3 and are affected in toxin oligomerization. These mutants do not show a DN phenotype but were able to block toxicity when used in 10:1 or 100:1 ratios (mutant:wt) probably by competition of binding with toxin receptors. Conclusions/Significance - We show that DN phenotype can be observed among different Cry toxins suggesting that may interact in vivo forming hetero-oligomers. The DN phenotype cannot be observed in mutants affected in oligomerization, suggesting that this step is important to inhibit toxicity of other toxin

Sea Level in the Strait of Gibraltar: Tides

A network of tide gauges with eight observation recording points was in operation in the Strait of Gibraltar during the years 1984 and 1985, which made it possible to draw up detailed charts of the tides showing their refined structure. For the first order, the Strait of Gibraltar represents the nodal line of the stationary wave of the western Mediterranean, which, hypothetically, would end at the Cadiz meridian (6°17.0W). The tide is basically semi-diurnal; on average, 90% of the energy is associated with the second order and, for this, the Strait of Gibraltar tends to represent an antinode of the stationary wave, although the influence of the bottom topography and the rotation is interpreted in phase delays in the sill area (slightly progressive wave) and in increased non-linear constituents of higher orders. The radiational tide S is evaluated in the area studied and it is ascertained that it shows the same characteristics as the tides having strictly gravitational constituents, which implies that it is fundamentally co-oscillating. Order 4 displays characteristics of resonant amplification due to the existence of the free oscillation mode of the western Mediterranean basin the period of which is close to 6 hours. Of order 3 it should be stressed that M3, though small, is perfectly detectable in the area

A numerical study of the Navier-Stokes transport coefficients for two-dimensional granular hydrodynamics

A numerical study that aims to analyze the thermal mechanisms of unsteady, supersonic granular flow by means of hydrodynamic simulations of the Navier–Stokes granular equation is reported in this paper. For this purpose, a paradigmatic problem in granular dynamics such as the Faraday instability is selected. Two different approaches for the Navier–Stokes transport coefficients for granular materials are considered, namely the traditional Jenkins–Richman theory for moderately dense quasi-elastic grains and the improved Garzó–Dufty–Lutsko theory for arbitrary inelasticity, which we also present here. Both the solutions are compared with event-driven simulations of the same system under the same conditions, by analyzing the density, temperature and velocity field. Important differences are found between the two approaches, leading to interesting implications. In particular, the heat transfer mechanism coupled to the density gradient, which is a distinctive feature of inelastic granular gases, is responsible for a major discrepancy in the temperature field and hence in the diffusion mechanisms

KLHL1 Controls CaV3.2 Expression in DRG Neurons and Mechanical Sensitivity to Pain

Dorsal root ganglion (DRG) neurons process pain signaling through specialized nociceptors located in their peripheral endings. It has long been established low voltage-activated (LVA) CaV3.2 calcium channels control neuronal excitability during sensory perception in these neurons. Silencing CaV3.2 activity with antisense RNA or genetic ablation results in anti-nociceptive, anti-hyperalgesic and anti-allodynic effects. CaV3.2 channels are regulated by many proteins (Weiss and Zamponi, 2017), including KLHL1, a neuronal actin-binding protein that stabilizes channel activity by recycling it back to the plasma membrane through the recycling endosome. We explored whether manipulation of KLHL1 levels and thereby function as a CaV3.2 modifier can modulate DRG excitability and mechanical pain transmission or sensitivity to pain. We first assessed the mechanical sensitivity threshold and DRG properties in the KLHL1 KO mouse model. KO DRG neurons exhibited smaller T-type current density compared to WT without significant changes in voltage dependence, as expected in the absence of its modulator. Western blot analysis confirmed CaV3.2 but not CaV3.1, CaV3.3, CaV2.1, or CaV2.2 protein levels were significantly decreased; and reduced neuron excitability and decreased pain sensitivity were also found in the KLHL1 KO model. Analogously, transient down-regulation of KLHL1 levels in WT mice with viral delivery of anti-KLHL1 shRNA also resulted in decreased pain sensitivity. These two experimental approaches confirm KLHL1 as a physiological modulator of excitability and pain sensitivity, providing a novel target to control peripheral pain.Fil: Martínez Hernández, Elizabeth. Loyola University Chicago; Estados UnidosFil: Zeglin, Alissa. Loyola University Chicago; Estados UnidosFil: Almazan, Erik. Loyola University Chicago; Estados UnidosFil: Perissinotti, Paula Patricia. Loyola University Chicago; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: He, Yungui. University of Minnesota; Estados UnidosFil: Koob, Michael. University of Minnesota; Estados UnidosFil: Martin, Jody L.. Loyola University Chicago; Estados UnidosFil: Piedras-Rentería, Erika S.. Loyola University Chicago; Estados Unido