Some breathers and multi-breathers for FPU-type chains

We consider several breather solutions for FPU-type chains that have been found numerically. Using computer-assisted techniques, we prove that there exist true solutions nearby, and in some cases, we determine whether or not the solution is spectrally stable. Symmetry properties are considered as well. In addition, we construct solutions that are close to (possibly infinite) sums of breather solutions

On a nonlinear nonlocal hyperbolic system modeling suspension bridges

We suggest a new model for the dynamics of a suspension bridge through a system of nonlinear nonlocal hyperbolic differential equations. The equations are of second and fourth order in space and describe the behavior of the main components of the bridge: the deck, the sustaining cables and the connecting hangers. We perform a careful energy balance and we derive the equations from a variational principle. We then prove existence and uniqueness for the resulting problem

Torsional instability in suspension bridges: the Tacoma Narrows Bridge case

All attempts of aeroelastic explanations for the torsional instability of suspension bridges have been somehow criticised and none of them is unanimously accepted by the scientific community. We suggest a new nonlinear model for a suspension bridge and we perform numerical experiments with the parameters corresponding to the collapsed Tacoma Narrows Bridge. We show that the thresholds of instability are in line with those observed the day of the collapse. Our analysis enables us to give a new explanation for the torsional instability, only based on the nonlinear behavior of the structure

Promises of Democratic Consent and Practices of Citizenship

On June 26, 2017, the U.S. Supreme Court upheld Proclamation 9645, also known as the “Travel Ban” or “Muslim Ban.” This resolution suspended the insurance of immigrant and non-immigrant visas to applicants from Libya, Iran, Somalia, Syria, and Yemen (which are Muslim-majority countries), plus North Korea and Venezuela. Because of Donald Trump’s decision, many American had their rights diminished: spouses were separated; children could not reunite with their parents; students felt hopeless about getting a job in the U.S.; and many felt trapped, unable to leave America for fear of not being able to reenter the country despite their legal status. The Supreme Court validated the executive branch’s ability to limit people’s freedom and many of their (internationally recognized) rights in the name of national security. People from the ‘banned’ countries were blocked from seeking asylum independently from their living conditions (Gladstone & Sugiyama, 2018: web).This event had the involuntary effect of revitalizing the memory of an old court case, the well-known Korematsu v. United States, and the haunting ghost of the Japanese internment camps. In both cases (Trump’s Proclamation 9645 and Franklin Delano Roosevelt’s Executive Order 9066), claims to national security were used to justify and mask ethnic, racial (and religious) animus. The lack of respect for individuals’ access to justice, in spite of their citizenship, the racist undertones present in both misinformed propaganda rhetorics, and the malicious detention of individuals are clear parallelisms connecting these two events (Wietelman, 2019). These correspondences were also (shamelessly) noticed by a pro-Trump Great American PAC spokesperson, who cited Japanese internment camps as ‘precedents’ for Muslim registry (Hartman, 2016: web). Likewise, the opposition often cited Korematsu as a notably bad decision and antecedent. For example, Justice Sotomayor manifested his dissent by comparing the ‘Travel Ban’ decision to Korematsu v. United States. Indeed, in both cases, one might question the constitutionality of means to separate neatly the “bad actors” from the larger group. In the Executive Order 9066, all persons of Japanese ancestry living in the western United States were part of the larger group, whereas the “bad actors” were citizens deemed to be disloyal. In Trump’s Proclamation 9645, the citizens of only eight countries composed the larger group, and the “bad actors” were those considered potential terrorists within that population. In both situations, the Court “abandoned judicial review over alleged infringement of constitutional rights asserted by American citizens arising from screening procedures” (Dean, 2018:176). This led many American to infer that Trump v. Hawaii was a reiteration of the Korematsu case.Given this context, it no surprise to see the reenactment of Japanese internment camps in contemporary graphic novel. Thus, these works can be seen as “memory projects” (Leavy, 2007) as they activate particular repositories of collective memory in order to bring certain aspects of the recent past into the public eye. These projects might be seen as attempts to resist dominant records of the event, allowing individual voices and (hi)stories to arise, as well as a means to disseminate new ideas about activism and citizenship. The choice of the medium is not neutral as it might be seen as an homage to one of the earliest vivid testimony of the Japanese incarceration, Miné Okubo’s (1946) Citizen 13660. Yet, it is important to remark that in the 1940s the medium comics was also involved in the dissemination of anti-Japanese and Anti-Asian sentiments. Finally, whereas previous revocations of the event in comic form aimed to make the public aware of present injustices (Okubo, 1946), denounce America’s long history of Asians’ exclusion policy (Yang et al. 2009) and counter the invisibility of Asians’ sufferings (Toyoshima, 2003), the more recent comics do not just aim to address these old questions, but to bring these debates within a “global civil sphere” (Alexander, 2012)

A (not so) Forgotten War: The Korean Conflict as a Turning Point in the History of the War Comics Genre

The Korean War did not leave a long-lasting mark in cultural memory, and it is usually described as the “Forgotten War.” This (partial) oblivion might be attributed to the fact that this war did not represent either a victory or a loss, but a ‘tie.’ The Korean War did not inspire as many novels or movies as the Second World War or the Vietnam War did (Rosso 2003). In sharp contrast to other media, in the 1950s, comic book publishers created a noticeable number of titles addressing the American military involvement in Korea (Rifas 2021). In this paper, I would like to address the cultural importance of these comics showing how they anticipated some of the themes (and fracture) that would emerge within America during the Vietnam War thanks to the Civil Rights Movement and the counterculture. Indeed, one can already observe the existence of two conflictual narratives. On one hand, building up on the medium tradition (as a propaganda tool), war comics tried to reaffirm the values of patriotism and duty, embodied by white masculine men fighting the Red (racialized) menace overseas, recirculating the same anti-Asian stereotypes used against Japanese during World War II. At the same time, their casting of women in traditional gendered roles foreshadows an important theme of the 1980s revisionist narrations of the Vietnam War, the “remasculinization of America” (Jeffords 1989). On the other hand, EC (War) comics started to question authority and official narratives, giving a more realistic portrayal of the war. They did not hesitate to describe its degrading aspects and moral contradiction. These comics were socially relevant as they provided th

On the dynamics of coupled oscillators and its application to the stability of suspension bridges

We describe and provide a computer assisted proof of the bifurcation graph for a system of coupled nonlinear oscillator described in a model of a bridge. We also prove the linear stability/instability of the branches of solutions

Optimization of the Forcing Term for the Solution of Two-Point Boundary Value Problems

We present a new numerical method for the computation of the forcing term of minimal norm such that a two-point boundary value problem admits a solution. The method relies on the following steps. The forcing term is written as a (truncated) Chebyshev series, whose coefficients are free parameters. A technique derived from automatic differentiation is used to solve the initial value problem, so that the final value is obtained as a series of polynomials whose coefficients depend explicitly on (the coefficients of) the forcing term. Then the minimization problem becomes purely algebraic and can be solved by standard methods of constrained optimization, for example, with Lagrange multipliers. We provide an application of this algorithm to the planar restricted three body problem in order to study the planning of low-thrust transfer orbits