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Enhanced Radial Stress Method (RSM) for cellular beams in EN 1993-1-13 to account for elasto-plastic behaviour
Full text linkIn cellular beams with circular openings, Vierendeel bending failure is caused by the local bending around the web openings in regions of high shear. In BS EN 1993-1-13, a Radial Stress Method (RSM) is presented, which is based either on the elastic resistance of the inclined T13 sections around the openings or on their plastic bending resistance dependent on the section classification of the inclined T-section, which results in a step between elastic and plastic properties. The RSM method also fails to account for stress redistribution between the lower moment side and the higher moment side of openings. This study investigates the RSM for circular openings in a typical UB 457x152x52 beam, that is modelled and analysed using Abaqus. The RSM is extended to an elasto-plastic analysis of the inclined T-sections that gives a way of evaluating the development of the Vierendeel bending mechanism and may be used for slender webs. The elasto-plastic analysis around the openings subject to axial force, shear and bending is based on a multiple of the yield strain at the edge of the opening. This is compared to the non-linear FEA results, which show good agreement for the stress distribution around the openings on the lower moment and higher moment sides of the openings for all combinations of applied shear and moment. The results of the method are also compared to cellular beam tests results failing in Vierendeel bending
“You’re a warrior, right?”: The Manosphere, Podcasts, and the Strongman Politics of Donald Trump in the 2024 United States Presidential Election
No full textIn the run up to the 2024 United States Presidential Election, President Donald Trump, in continuing his disapproval, disavowal, and eschewing of ‘mainstream media’, increasingly turned to influencers and podcasters as mediums through which to speak to his followers and prospective voters. A core feature of this strategy were alternative media platforms not immediately related to the political sphere, but to sport related podcasts and ‘bro influencers’ that cater to a predominantly male audience - such as UFC Unfiltered and The Joe Rogan Experience. Trump’s efforts to fit within a media landscape where the capacities of sporting, fitness, and ‘body building’ subcultures (re)produce deviant masculinities also endorsed conservative and authoritarian political movements. This paper presents a discursive and contextual analysis of Trump’s podcast appearances in the 2024 election cycle. We explore the growing inter-relationship between gender, masculinities, sport, and ‘the manosphere’ - the loose constellation of reactionary, anti-feminist and misogynistic movements often propagated in digital spaces by online influencers, reactionary conservative politics and, more specifically, Trumpism. We argue that within Trumpism, alternative sport and fitness media become sites whereby discourses of deviant and ‘alpha’ masculinity and the male body are constructed and activated as resources for political capital. We conclude by considering the importance of sport and leisure – such as the fitness and sporting subcultures embodied in conservative politics and the digital ecosystems through which they proliferate - in (re)shaping political movements in a digital age
Rising temperatures and physical pain: Evidence from over 2 million U.S. residents
No full textPhysical pain is on the rise worldwide, yet little is known about its relationship with rising temperatures. Using daily survey data on more than 2 million U.S. residents from 26,987 zip codes between 2008 and 2017, we examine whether hotter days are associated with greater reports of pain. Our outcome captures whether respondents experienced physical pain for a substantial part of the day, reflecting the prevalence of sustained daily pain rather than fleeting discomfort. We find that the likelihood of such pain increases steadily with temperature up to around 16–18 °C and remains elevated, though with smaller further increases, on hotter days. On days with temperatures of 32 °C or higher, the probability of reporting pain is about 0.45 percentage points higher—an increase of roughly 1.9 % relative to the average prevalence. Analyses of stress, enjoyment, and activity limitation suggest that physiological pathways play an important role in this association, complementing possible behavioural responses. Using climate projection data (CMIP5, SSP2–4.5), we estimate that temperature-driven increases in pain prevalence between 2008 and 2017 imposed annual economic costs of approximately 9.4 billion by 2050 if no adaptation measures are taken. These findings suggest that temperature deviations from moderate ranges exacerbate physical suffering, with the heat effects likely understated in our data, and underscore the need for policies that mitigate both climatic and health impacts
(Un)Frozen in Time: Temporal Politics, UN Peacekeeping, and the Gaza Exception
Full text linkScholars are increasingly interrogating distinctions between ‘war time’ and ‘peace time’, but what happens when time itself becomes a weapon of war or, even, a model of conflict response. Focusing on the case study of the first armed UN mission, the United Nations Emergency Force (UNEF) to Sinai and the Gaza Strip during the 1956 Suez Crisis, I examine the mission’s attempt to replace the Israeli invasion and establish an open-ended international administration on the Gaza Strip. Using archival documents and photographs, this paper explores how UN operations in Palestine shaped temporal assumptions about the population and the conflict. I argue that the Suez Crisis ruptured an UN-managed temporal paralysis on the Gaza Strip which opened up opportunities for new futures in Gaza, as well as anxiety to return to controlled paralysis. Examining both Palestinian and international reactions to the UN occupation, I show how the ‘Gaza exception’ policy transformed international perceptions of the region – its past, present, and future. Thus, by focusing on the moment of the brief UN occupation, I argue that this international intervention shifted global perceptions of the strip from a ‘frozen’ site of past conflict into a space of unfinished ownership and future potentiality
Transient development of the leading-edge vortex and its role in unsteady aerodynamic load variations
Full text linkLarge eddy simulations are conducted for a pitching National Advisory Committee for Aeronautics 63(3)418 airfoil section at a reduced frequency of K=0.4 and a chord-based Reynolds number, Rec=100 000. The goal of this work is to understand how transient stall flutter dynamics are affected by initial flow field conditions associated with a high incidence angle. Perturbation starting times are varied parametrically to investigate the differences in the transient dynamic stalling processes over a single pitching cycle. It is found that Kármán vortex shedding associated with an initially static airfoil interferes with the leading-edge vortex detachment and dynamic lift stall as per large variations in the post-stall unsteady aerodynamic loading. Monitored leading-edge vortex trajectories and computed Lagrangian averaged vorticity deviation fields both confirm this notion and are utilized to link this phenomenon to the status of a trailing-edge vortex. It is shown that the leading-edge vortex trajectory standard deviation leading up to dynamic lift stall contracts at a singular point in space. This event appears to be weakly connected to the leading-edge vortex circulation during its maturation stage. The leading-edge vortex morphology is also investigated near its detachment location through several morphometric quantifiers such as the area, aspect ratio, and eccentricity. It is found that the leading-edge vortex morphology undergoes a similar contraction in the aspect ratio and eccentricity standard deviations. Finally, near-surface measurements of the u and v signals grant an indirect quantification of the leading-edge vortex strength and position as it advects over the airfoil chord
Bayes or Pascal? The computations underlying motivated reasoning
Full text linkThe construct of motivated reasoning has inspired an influential body of research. However, most theories of this construct are expressed in a verbal form. This is somewhat limited in light of contemporary research in cognitive science that emphasizes the insight afforded by employing computational modeling. To address this, the paper introduces a computational model of motivated reasoning. The model builds on previous accounts of belief formation based on Bayesian inference by adding computations concerning value or utility. The result is an interpretation of motivated reasoning as being akin to a process reflecting an unconscious Bayesian decision, in a way that is reminiscent of the famous Pascal’s wager. This framework is broadly consistent with empirical evidence, especially about the effect of loss function asymmetries on probability judgments, about the confirmation bias, and about the backfire effect. Moreover, it is compatible with evolutionary explanations of motivated reasoning that interpret this phenomenon as ensuing from self-deception. The model helps understanding the computational principles behind the concept of motivated reasoning. Moreover, it facilitates the comparison between perspectives that downplay motivated reasoning and theories that emphasize its role. This may inform empirical research aimed at establishing the real contribution of motivated reasoning during belief formation
Which GRS Statistic Is Appropriate for Cross-Sectional Tests of Linear Multi-Factor Pricing Models?
No full textFama and French (2015, 2017) introduce the five‐factor asset pricing model in the former paper and test their model on data from international financial markets in the latter paper. Each paper tests whether the five‐factor model represents returns by way of the Gibbons, Ross and Shanken (1989) (hereafter GRS) statistic. That statistic's null hypothesis jointly sets all cross‐section intercepts (alpha) to zero. The GRS statistic developed and presented in equation (4) on page 1124 of GRS (1989) is a cross‐section test of the one‐factor capital asset pricing model. Using the same data as Fama and French (2015, 2017), we show that the latter authors did not use the GRS (1989) statistic given in equation (4) on page 1124. In fact, they used a version of that statistic appropriate for the five‐factor model. To provide clarity on this issue, this paper provides a detailed mathematical derivation of the cross‐sectional variance of the OLS estimators of the intercepts when
N
versions of the
K
‐factor model are estimated. This variance is then used to construct the enhanced version of the GRS statistic. Its finite sample distribution is then rigorously established. To obtain that distribution, restrictions are made on cross‐sectional variances and covariances of the errors of pricing models that are inconsistent with times series data. We derive the variance–covariance of the estimated intercepts of the
K
‐factor model without making these restrictions. An almost sure approximation to that estimator is constructed here which is then used to obtain the asymptotic distribution of the GRS statistic. We call it the robust GRS statistic. Using data of Fama and French (2015, 2017), we use the robust GRS statistic to reconstruct their tables 5 and 4, respectively. As the distribution of the robust GRS does not change with the number of factors, in contrast to the finite sample version of this statistic, it allows for a more nuanced comparison of three‐, four‐ and five‐factor models. The power functions of the GRS (1989) statistic are compared with the enhanced version of the GRS appropriate for
K
factors
Lie symmetries and Ghost-free representations of the Pais–Uhlenbeck model
No full textWe investigate the Pais–Uhlenbeck (PU) model, a paradigmatic example of a higher time-derivative theory, by identifying the Lie symmetries of its associated fourth-order dynamical equation. Exploiting these symmetries in conjunction with the model’s Bi-Hamiltonian structure, we construct distinct Poisson bracket formulations that preserve the system’s dynamics. Amongst other possibilities, this allows us to recast the PU model in a positive definite manner, adding another solution to the long-standing problem of ghost instabilities. Furthermore, we systematically explore a family of transformations that reduce the PU model to equivalent first-order, higher-dimensional systems. Finally we examine the impact on those transformations by adding interaction terms of potential form to the PU model and demonstrate how they usually break the Bi-Hamiltonian structure. Our approach yields a unified framework for interpreting and stabilizing higher time-derivative dynamics through a symmetry analysis in some parameter regime
Three-dimensional ghost-free representations of the Pais-Uhlenbeck model from Tri-Hamiltonians
No full textWe present a detailed analysis of the sixth-order Pais-Uhlenbeck oscillator and construct three-dimensional ghost-free representations through a Tri-Hamiltonian framework. We identify a six-dimensional Abelian Lie algebra of the PU model’s dynamical flow and derive a hierarchy of conserved Hamiltonians governed by multiple compatible Poisson structures. These structures enable the realisation of a complete Tri-Hamiltonian formulation that generates identical dynamical flows. Positive-definite Hamiltonians are constructed, and their relation to the full Tri-Hamiltonian hierarchy is analysed. Furthermore, we develop a mapping between the PU model and a class of three-dimensional coupled second-order systems, revealing explicit conditions for ghost-free equivalence. We also explore the consequences of introducing interaction terms, showing that the multi-Hamiltonian structure is generally lost in such cases
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