60,721 research outputs found

    Effect of gravitational radiation reaction on nonequatorial orbits around a Kerr black hole

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    The effect of gravitational radiation reaction on orbits around a spinning black hole is analyzed. Such orbits possess three constants of motion: iota, e, and a, which correspond, in the Newtonian limit of the orbit being an ellipse, to the inclination angle of the orbital plane to the hole's equatorial plane, the eccentricity, and the semimajor axis length, respectively. First, it Is argued that circular orbits (e = 0) remain circular under gravitational radiation reaction. Second, for elliptical orbits (removing the restriction of e = 0), the evolution of iota, e, and a is computed to leading order in S (the magnitude of the spin angular momentum of the hole) and in M/a, where M is the mass of the black hole. As a decreases, iota increases and e decreases

    Who Cares How Congress Really Works?

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    Legislative intent is a fiction. Courts and scholars accept this, by and large. As this Article shows, however, both are confused as to why legislative intent is a fiction and as to what this fiction entails. This Article first argues that the standard explanation—that Congress is a “they,” not an “it”—rests on an unduly simple conception of shared agency. Drawing from contemporary scholarship in the philosophy of action, it contends that Congress has no collective intention, not because of difficulties in aggregating the intentions of individual members, but rather because Congress lacks the sort of delegatory structure that one finds in, for example, a corporation. Second, this Article argues that—contrary to a recent, influential wave of scholarship—the fictional nature of legislative intent leaves interpreters of legislation with little reason to care about the fine details of legislative process. It is a platitude that legislative text must be interpreted in “context.” Context, however, consists of information salient to author and audience alike. This basic insight from the philosophy of language necessitates what this Article calls the “conversation” model of interpretation. Legislation is written by legislators for those tasked with administering the law—for example, courts and agencies—and those on whom the law operates—for example, citizens. Almost any interpreter thus occupies the position of conversational participant, reading legislative text in a context consisting of information salient both to members of Congress and to citizens (as well as agencies, courts, etc.). The conversation model displaces what this Article calls the “eavesdropping” model of interpretation—the prevailing paradigm among both courts and scholars. When asking what sources of information an interpreter should consider, courts and scholars have reliably privileged the epistemic position of members of Congress. The result is that legislation is erroneously treated as having been written by legislators exclusively for other legislators. This tendency is plainest in recent scholarship urging greater attention to legislative process—the nuances of which are of high salience to legislators but plainly not to citizens

    A Model for Collective Dynamics in Ant Raids

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    Ant raiding, the process of identifying and returning food to the nest or bivouac, is a fascinating example of collective motion in nature. During such raids ants lay pheromones to form trails for others to find a food source. In this work a coupled PDE/ODE model is introduced to study ant dynamics and pheromone concentration. The key idea is the introduction of two forms of ant dynamics: foraging and returning, each governed by different environmental and social cues. The model accounts for all aspects of the raiding cycle including local collisional interactions, the laying of pheromone along a trail, and the transition from one class of ants to another. Through analysis of an order parameter measuring the orientational order in the system, the model shows self-organization into a collective state consisting of lanes of ants moving in opposite directions as well as the transition back to the individual state once the food source is depleted matching prior experimental results. This indicates that in the absence of direct communication ants naturally form an efficient method for transporting food to the nest/bivouac. The model exhibits a continuous kinetic phase transition in the order parameter as a function of certain system parameters. The associated critical exponents are found, shedding light on the behavior of the system near the transition.Comment: Preprint Version, 30 pgs., 18 figures, complete version with supplementary movies to appear in Journal of Mathematical Biology (Springer

    The Effect of Slow Two‐Electron Transfers and Disproportionation on Cyclic Voltammograms

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    The EE mechanism (two‐electron transfer) for cyclic voltammetry was investigated in considerable detail along with the effect of disproportionation. The theory was developed for either the first or second electron transfer being slow while the other one was reversible. It was possible to develop generalized working curves for the height and shape of the wave regardless of the difference in Eo\u27s and the values of α and Ks. This theory was then applied to the analysis of the reduction of benzil in the presence of alkaline earth ions in dimethylformamide

    “We the undersigned
bind ourselves mutually”: Civil War Draft Resistance in Eastern Pennsylvania

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    On August 6th, 1863, a group of sixteen men gathered at the East Penn Railroad depot in Millerstown, Pennsylvania, now known as Macungie, a small farming community located about seven miles southwest of Allentown. The young men met that day to create a contract with one another in anticipation of the army conscription draft, scheduled to take place in a week’s time with men between ages twenty and thirty-five eligible for selection. They created the “Millerstown Club,” agreeing “that each member of the club has to pay the sum of fifty dollars on or before the day previous to the draft.” Should the misfortune of being drafted fall upon any members of the club, the money collected would be used either to hire a substitute to serve in the army in the club member’s place or to pay the “commutation” fee of $300 to free them from service entirely. Any signer of the contract who did not pay his share by the day before the draft would not be considered a member should he be drafted. This apparently happened in the case of three of the men, who have their names crossed out on the contract. The creation of the “Millerstown Club” reflected a strong desire to avoid the war among the draft-eligible men of the town. [excerpt

    “Died of the Spotted Fever”: The Spot Resolutions and the Making of Abraham Lincoln

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    On December 22, 1847, the Speaker of the House of Representatives recognized a young, freshman congressman from Illinois named Abraham Lincoln who wished to speak about the ongoing war with Mexico. The lanky, awkward, high-voiced westerner raised doubts regarding President James Knox Polk’s conduct in starting the war, proposing eight resolutions that challenged Polk to provide evidence for his stated reason for doing so. Polk had said that Mexican troops had shed “American blood on American soil” and forced his hand, but Lincoln challenged this assertion. Lincoln insinuated that the fatal encounter between Mexican and American troops had in fact occurred in a contested region between the Nueces River and the Rio Grande, a region to which Mexico had stronger claims than the United States. With his demand that Polk prove that the exact location of the engagement had been on American soil, Lincoln’s proposals became known as the “Spot Resolutions.” This speech brought Lincoln into the national spotlight for the first time, and it proved key in the development of his future career. [excerpt

    Improving the Present by Studying the Past: Killed at Gettysburg Remembers O’Rorke and Phelps

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    This semester, I have had the honor of working on the Civil War Institute’s Killed at Gettysburg project, hosted at killedatgettysburg.org. The project seeks to document the lives and legacies of soldiers who died during the three days of fighting in July 1863. I am happy to be contributing to Killed at Gettysburg again, as I strongly connected with the project when I worked on it for Dr. Carmichael’s Gettysburg class last semester. [excerpt

    MS-235: LTC Richard F. Pendleton ‘63 Papers

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    The collection includes maps, photographs, documents, and correspondence related to the service of LTC Richard F. Pendleton ’63 and the Vietnam War. These include detailed maps and items highlighting aspects of Pendleton’s time in Vietnam and broader pieces regarding different aspects of the Vietnam War era. Much of this correspondence is in the form of e-mails written many years after the war, and thus includes the personal opinions and biases of their authors. The printed articles included in the collection were also selected by Pendleton and reflect his interests and opinions on the war and its aftermath; they are not necessarily sources original to the Vietnam War era. The collection includes deep information on and discussions of Pendleton’s advisory team and its operations in Vietnam as a major strength, though it may not be as useful for those seeking first-hand information of those who served in different types of units and organizations. Potential research interests include the work of MACV Advisory Teams, intelligence operations in Vietnam, and veterans’ perspectives on the war. This collection includes some graphic content in Binder 1-2, most notably images of dead Viet Cong soldiers. Special Collections and College Archives Finding Aids are discovery tools used to describe and provide access to our holdings. Finding aids include historical and biographical information about each collection in addition to inventories of their content. More information about our collections can be found on our website https://www.gettysburg.edu/special-collections/collections/.https://cupola.gettysburg.edu/findingaidsall/1200/thumbnail.jp

    Diffusion Approximations for Demographic Inference: DaDi

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    Models of demographic history (population sizes, migration rates, and divergence times) inferred from genetic data complement archeology and serve as null models in genome scans for selection. Most current inference methods are computationally limited to considering simple models or non-recombining data. We introduce a method based on a diffusion approximation to the joint frequency spectrum of genetic variation between populations. Our implementation, DaDi, can model up to three interacting populations and scales well to genome-wide data. We have applied DaDi to human data from Africa, Europe, and East Asia, building the most complex statistically well-characterized model of human migration out of Africa to date
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