This article contributes to explaining the rise of labor unrest in Egypt in the early 2000s, led initially by public-sector workers. Using two case studies in textile and transport, the author shows ...that perceptions of sector potential affected workers’ ability to protest and compensated for the decline in their sectors’ roles in the economy. The perceptions of underutilization due to corruption and to sector viability based on squandered profits help explain workers’ militancy and capacities to mount an extended protest campaign. These perceptions build on discourses that critique the state’s adoption of neoliberal policies associated with privatization. Workers could develop these perceptions because their sectors still played a role in the economy despite their decline. The analysis contributes to the Power Resource Approach by showing how perceptions of sector potential enhance capacities among Global South workers in declining sectors. To explain labor unrest, the author engages labor scholarship on Egypt that focuses on grievances rather than on workers’ economic position and sources of power.
Summary
The seismic performance of tuned mass dampers (TMDs) on structures undergoing inelastic deformations may largely depend on the ground motion intensity. By estimating the impact of each ...seismic intensity on the overall cost of future seismic damages, lifecycle cost (LCC) proves a rational metric for evaluating the benefits of TMDs on inelastic structures. However, no incorporation of this metric into an optimization framework is reported yet. This paper presents a methodology for the LCC‐optimal design of TMDs on inelastic structures, which minimizes the total seismic LCC of the combined building‐TMD system. Its distinctive features are the assumption of a mass‐proportional TMD cost model, the adoption of an iterative suboptimization procedure, and the initialization of the TMD frequency and damping ratios according to a conventional linear TMD design technique. The methodology is applied to the seismic improvement of the SAC‐LA benchmark buildings, taken as representative of standard steel moment‐resisting frame office buildings in LA, California. Results show that, despite their limited performance at the highest intensity levels, LCC‐optimal TMDs considerably reduce the total LCC, to an extent that depends on both the building vulnerability and the TMD unit cost. They systematically present large mass ratios (around 10%) and frequency and damping ratios close to their respective linearly designed optima. Simulations reveal the effectiveness of the proposed design methodology and the importance of adopting a nonlinear model to correctly evaluate the cost‐effectiveness of TMDs on ordinary structures in highly seismic areas.
Summary
Passive tuned mass dampers (TMDs) are widely used in controlling structural vibrations. Although their principle is well established, the search for improved arrangements is still under way. ...This effort has recently produced an innovative paradigm of bidirectional pendulum TMD (BTMD) that, moving along a specially designed three‐dimensional (3D) surface, can simultaneously control two in‐plane orthogonal structural modes. In existing versions of BTMDs, energy dissipation is provided either by ordinary horizontal viscous dampers or by an original arrangement of vertical friction dampers. In this paper, a new paradigm is proposed, in which energy dissipation comes from the tangential friction arising along the pendulum surface out of an optimal spatially variable friction coefficient pattern. Within this paradigm, if the friction coefficient is taken proportional to the modulus of the pendulum surface gradient, the dissipation model results nonlinear homogeneous in the small‐displacement domain, and the performance of the absorber, herein called the homogeneous tangential friction BTMD (HT‐BTMD), results independent from the excitation level. The present work introduces this concept, derives the analytical model of the HT‐BTMD, establishes a method for its optimal design, and numerically verifies its seismic effectiveness in comparison with viscously damped devices. The validity and feasibility of the concept are demonstrated through experimental tests on a small‐scale lab prototype, which also show the efficacy of a stepwise approximation of the homogeneous friction pattern. The new device proves a competing alternative to existing BTMDs, and homogeneous tangential friction proves a promising new paradigm to provide pendular systems with amplitude‐independent structural damping.
TRPV1 and TRPM8 are sensory nerve ion channels activated by heating and cooling, respectively. A variety of physical and chemical
stimuli activate these receptors in a synergistic manner but the ...underlying mechanisms are unclear. Both channels are voltage
sensitive, and temperature and ligands modulate this voltage dependence. Thus, a voltage-sensing mechanism has become an attractive
model to explain the generalized gating of these and other thermo-sensitive TRP channels. We show here using whole-cell and
single channel measurements that voltage produces only a partial activation of TRPV1 and TRPM8. At room temperature (20â25°C)
membrane depolarization evokes responses that saturate at â¼50â60% of the maximum open probability. Furthermore, high concentrations
of capsaicin (10 μ m ), resiniferatoxin (5 μ m ) and menthol (6 m m ) reveal voltage-independent gating. Similarly, other modes of TRPV1 regulation including heat, protein kinase C-dependent
phosphorylation, and protons enhance both the efficacy and sensitivity of voltage activation. In contrast, the TRPV1 antagonist
capsazepine produces the opposite effects. These data can be explained by an allosteric model in which voltage, temperature,
agonists and inverse agonists are independently coupled, either positively or negatively, to channel gating. Thus, voltage
acts separately but in concert with other stimuli to regulate channel activation, and, therefore, a voltage-sensitive mechanism
is unlikely to represent a final, gating mechanism for these channels.
Electrochemical reduction of dinitrogen molecules (N
) to value-added ammonia by using renewable electricity under mild conditions is regarded as a sustainable and promising strategy for N
fixation. ...However, the lack of efficient, robust and inexpensive electrocatalysts for such electrochemical reduction has prevented its wide application. Herein, we report a novel single-atom catalyst, i.e., a single tungsten (W) atom anchored on N-doped graphyne (W@N-doped graphyne) as a highly efficient and low-cost electrocatalyst for the N
reduction reaction. The inert Ntriple bond, length as m-dashN triple bond can be sufficiently activated when an N
molecule is adsorbed on the W atom. A single atom of W coordinated with one N atom (doping into an sp-hybridized carbon atom) exhibits the highest catalytic performance with ultra-low onset potential of 0.29 V for N
reduction reactions. The 'distal mechanism' is identified as the most favourable catalytic pathway. Moreover, the improved electrical conductivity of W@N-doped graphyne compared to that of pristine graphyne can ensure better electron transfer efficiency during the reduction processes. Our study provides a novel electrocatalyst with excellent catalytic performance for electrochemical reduction of N
to NH
under ambient conditions.
In this article, we examine several techniques that allow for the construction of bounds estimates based on instrumental variables, even when the instruments are not valid. We introduce the plausexog ...and imperfectiv commands, which implement methods described by Conley, Hansen, and Rossi (2012, Review of Economics and Statistics 94: 260–272) and Nevo and Rosen (2012b, Review of Economics and Statistics 94: 659–671). We examine the performance of these bounds under a range of circumstances, which leads to several practical results related to the informativeness of the bounds in different situations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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