Insects are excellent fliers because of their ability to generate precise wing kinematics and deform their wings for the sufficient production of unsteady aerodynamic forces. Most of the previous ...studies on the effects of wing kinematics on the aerodynamics have been limited to the use of rigid wings, and leaves the contribution of wing flexibility unknown. Here, an experiment was conducted to investigate the effect of varied sweep duration and timing of rotation on the unsteady aerodynamic characteristics of hovering flexible and rigid wings at Re of 104. This study found that the forces generated by the flexible wing showed a conspicuous phase delay, which was more sensitive to the change in sweep duration than the timing of rotation. The transient negative lift associated with rigid wings undergoing delayed and advanced wing rotations totally disappeared in the flexible case. A digital particle image velocimetry (DPIV) measurement at the middle of stroke revealed a slight difference in the vortical structures surrounding the two wings in terms of proximity to the shed trailing-edge vortices (TEVs). Also, the linearly twisted nature of the flexible wing caused the coherent leading-edge vortex (LEV) to be stabilized throughout the wingspan. This increased the radial limit of the delayed stall from 3.6c in the rigid wing to 4.8c in the flexible wing. In general, the flexible wing with symmetric and delayed wing rotations generated the higher efficiency. The corresponding net force vectors were tilted in an almost vertical direction in comparison to the rigid wing. This is an indication that natural fliers adopt specific wing kinematics in addition to their wing deformation for the upward titling of their net force vector, which will significantly enhance their aerodynamic performance.
The mechanics of Dipteran thorax is dictated by a network of exoskeletal linkages that, when deformed by the flight muscles, generate coordinated wing movements. In Diptera, the forewings power ...flight, whereas the hindwings have evolved into specialized structures called halteres, which provide rapid mechanosensory feedback for flight stabilization. Although actuated by independent muscles, wing and haltere motion is precisely phase-coordinated at high frequencies. Because wingbeat frequency is a product of wing-thorax resonance, any wear-and-tear of wings or thorax should impair flight ability. How robust is the Dipteran flight system against such perturbations? Here, we show that wings and halteres are independently driven, coupled oscillators. We systematically reduced the wing length in flies and observed how wing-haltere synchronization was affected. The wing-wing system is a strongly coupled oscillator, whereas the wing-haltere system is weakly coupled through mechanical linkages that synchronize phase and frequency. Wing-haltere link acts in a unidirectional manner; altering wingbeat frequency affects haltere frequency, but not vice versa. Exoskeletal linkages are thus key morphological features of the Dipteran thorax that ensure wing-haltere synchrony, despite severe wing damage.
Recent research has showed that people with right-wing political orientations and political extremists are more likely to harbor conspiracy beliefs. Utilizing a multisite data set (23 countries, N > ...20,000), we show that corruption moderates how political orientation predicts conspiracy beliefs. We found that (1) the difference between left- and right-wingers in terms of adopting a conspiracy mind-set is attenuated in countries with high corruption; and (2) left-wingers are more likely to believe left-wing conspiracy theories, and right-wingers are more likely to believe right-wing conspiracy theories in high corruption countries. Including quadratic effects of political orientation yielded the same results. We argue that this is because corruption increases perceived plausibility of conspiracies, and everyone across the political spectrum becomes similarly likely to adopt a conspiracy mentality. This heightened suspicion, however, is reflected on partisan conspiracy theories differently for left- and right-wingers, depending on their different understandings of outgroup.
Despite the ongoing need for researchers, practitioners, and policymakers to identify and assess the online activities of violent extremists prior to their engagement in violence offline, little is ...empirically known about their online behaviors generally or differences in their posting behaviors compared to non-violent extremists who share similar ideological beliefs particularly. In this study, we drew from a unique sample of violent and non-violent right-wing extremists to compare their posting behaviors within a sub-forum of the largest white supremacy web-forum. Analyses for the current study proceeded in three phases. First, we plotted the average posting trajectory for users in the sample, followed by an assessment of the rates at which they stayed active or went dormant in the sub-forum. We then used logistic regression to examine whether specific posting behaviors were characteristic of users' violence status. The results highlight a number of noteworthy differences in the posting behaviors of violent and non-violent right-wing extremists, many of which may inform future risk factor frameworks used by law enforcement and intelligence agencies to identify credible threats online. We conclude with a discussion of the implications of this analysis, its limitations and avenues for future research.
A groundbreaking history of Europe's "new lefts, " from the antifascist 1920s to the anti-establishment 1960s In the 1960s, the radical youth of Western Europe's New Left rebelled against the ...democratic welfare state and their parents' antiquated politics of reform. It was not the first time an upstart leftist movement was built on the ruins of the old. This book traces the history of neoleftism from its antifascist roots in the first half of the twentieth century, to its postwar reconstruction in the 1950s, to its explosive reinvention by the 1960s counterculture.Terence Renaud demonstrates why the left in Europe underwent a series of internal revolts against the organizational forms of established parties and unions. He describes how small groups of militant youth such as New Beginning in Germany tried to sustain grassroots movements without reproducing the bureaucratic, hierarchical, and supposedly obsolete structures of Social Democracy and Communism. Neoleftist militants experimented with alternative modes of organization such as councils, assemblies, and action committees. However, Renaud reveals that these same militants, decades later, often came to defend the very institutions they had opposed in their youth.Providing vital historical perspective on the challenges confronting leftists today, this book tells the story of generations of antifascists, left socialists, and anti-authoritarians who tried to build radical democratic alternatives to capitalism and kindle hope in reactionary times.
Insects are one of the most agile flyers in nature, and studying the kinematics of their wings can provide important data for the design of insect-like wing-flapping micro aerial vehicles. This study ...integrates high-speed photogrammetry and three-dimensional (3D) force measurement system to explore the kinematics of Cyrtotrachelus buqueti during the wing-flapping flight. The tracking point at the wing tip of the hind wing was recorded using high-speed videography. The lift-thrust force characteristic of wing-flapping motion was obtained by the 3D force sensor. Quantitative measurements of wing kinematics show that the wing-flapping pattern of the hind wing of C. buqueti was revealed as a double figure-eight trajectory. The kinematic modelling of the wing-flapping pattern was then established by converting the flapping motion into rotational motion about the pivoting wing base in the reference coordinate system. Moreover, the lift force generated by C. buqueti during the wing-flapping flight is sufficient to support its body weight without the need to use thrust force to compensate for the lack of lift force.
The assumption that populist right-wing parties (PRWPs) thrive when the economy slows down is remarkably pervasive. What is often neglected is evidence showing PRWPs can thrive in times of economic ...prosperity. To examine this, we conducted an experiment in which participants were exposed to different appraisals of the future of the national economy and were subsequently asked to evaluate an anti-immigration speech (Study 1). Results showed stronger anti-immigrant sentiments when the national economy was presented as prospering rather than contracting. We then analyzed speeches by PRWP leaders who secured electoral victories during economic prosperity (Study 2) and found that these leaders encourage a sense of injustice and victimhood by portraying ordinary citizens as the victim of an alliance between powerful groups (the elite) and less powerful groups (refugees, immigrants, minorities). More specifically, Study 2 showed that PRWP leaders are crafty identity entrepreneurs who are able to turn objective relative gratification into perceived relative deprivation. We conclude that it is hence problematic to treat PRWP support as evidence of "resonance" with public sentiments and urge PRWP scholars interested in supply-side factors to engage with the social identity literature on leadership, follower ship, and social influence.
Drag reduction of the wings of migrating birds is crucial to their flight efficiency. Wing color impacts absorption of solar irradiation which may affect drag but there is little known in this area. ...To this end, the drag reduction induced by the thermal effect of the wing color of migrating birds with unpowered flight modes is presented in this study. Considering this natural phenomenon in the albatross as an example of migrating birds, and applying an energy balance for this biological system, a thermal analysis is performed on the wings during the summer and winter to obtain different ranges of air density, viscosity, and wing surface temperature brought about from a range of ambient temperatures and climatic conditions seen in different seasons and to study their effects. The exact shape of the albatross wing is used and nine different wing colors are considered in order to gain a better understanding of the effect different colors’ absorptivities make on the change in aerodynamic performances. The thermal effect is found to be more important during the summer than during the winter due to the higher values of solar irradiation and a maximum drag reduction of 7.8% is found in summer changing the wing color from light white to dark black. The obtained results show that albatrosses with darker colored wings are more efficient (constant lift to drag ratio and drag reduction) and have better endurance due to this drag reduction.
•The drag reduction of wing color of migrating birds with unpowered flight modes is presented.•A thermal analysis for boundary layer of albatross wings is performed.•The exact airfoil and shape of the albatross wing with nine different colors is considered.•Various aerodynamic methods including, LLT, VLM, and 3d-Panel method are employed.•A maximum drag reduction of 7.8% is found changing the wing color from white to black.
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