2,456 research outputs found
Equality of P-partition generating functions
To every labeled poset (P,\omega), one can associate a quasisymmetric
generating function for its (P,\omega)-partitions. We ask: when do two labeled
posets have the same generating function? Since the special case corresponding
to skew Schur function equality is still open, a complete classification of
equality among (P,\omega) generating functions is likely too much to expect.
Instead, we determine necessary conditions and separate sufficient conditions
for two labeled posets to have equal generating functions. We conclude with a
classification of all equalities for labeled posets with small numbers of
linear extensions.Comment: 24 pages, 19 figures. Incorporates minor changes suggested by the
referees. To appear in Annals of Combinatoric
G-133: A soft x ray solar telescope
The GOLDHELOX Project, NASA payload number G-133, is a robotic soft x ray solar telescope designed and built by an organization of undergraduate students. The telescope is designed to observe the sun at a wavelength of 171 to 181 A. Since we require observations free from atmospheric interference, the telescope will be launched in a NASA Get-Away-Special (GAS) canister with a Motorized Door Assembly (MDA). In this paper we primarily discuss the most important elements of the telescope itself. We also elaborate on some of the technical difficulties associated with doing good science in space on a small budget (about $100,000) and mention ways in which controlling the instrument environment has reduced the complexity of the system and thus saved us money
Unwed Motherhood in Nineteenth-Century English Canada
Dans la société du XIXe siècle, grossesses et naissances illégitimes étaient considérées comme de graves manquements au code de l'honneur qui prévalait à l'époque. La littérature en témoigne d'ailleurs fort éloquemment puisque, dans les nombreux romans qui exploitent ce thème, la mère célibataire est toujours marquée par la honte, l'ostracisme et, souvent même, par une mort prématurée.Qu'en était-il, cependant, dans la réalité ? C'est sur ce problème que se penche l'auteur de cet article, à partir de l'exemple du Canada anglais au XIXe siècle. Ainsi, il s'arrête d'abord aux taux d'illégitimité qui sont établis pour la période; il examine les implications légales qui sont rattachées au fait de la naissance illégitime; puis, il étudie quelques-uns des secours auxquels les mères célibataires et leurs enfants avaient accès, qu'il s'agisse de l'aide apportée par la famille ou de celle offerte par diverses institutions de l'époque. Enfin, il conclut que la femme aux prises avec le problème d'une grossesse illégitime au Canada anglais, pendant le XIXe siècle, n'a pas véritablement vécu les déboires qu'ont essuyés les personnages féminins de la littérature contemporaine, et ce, quelque soit la gravité de leur crime ou l'inconvenance de leur conduite
Optimizing ship-to-shore movement for Hospital Ship humanitarian assistance operations
The U.S. Navy recently designated Humanitarian Assistance (HA) and Disaster Relief (DR) as core capabilities, recognizing the importance of delivering a potent strategic communications message directly to foreign populations. The Ship-to-Shore Transportation Problem (SSTP) refers to the daily need to determine transportation asset (embarked helicopters, watercraft, and ground vehicles) routing and loading to effect the movement of personnel and patients between Hospital Ship (T-AH) and ashore mission sites during HA/DR operations. The SSTP significantly impacts overall mission performance. The SSTP is formulated as a mixed-integer mathematical optimization model, minimizing cost in a multi-objective merit function reflecting mission performance, personnel strength and transportation asset utilization while reflecting constraints unique to T-AH HA (flight deck limitations, restricted embarkation and debarkation by watercraft). Optimized schedules improve average duration of ashore mission site operations by between 9% and 13% compared to a set of optimistic, pseudo-manually generated schedules, and decrease average time spent by personnel in transit by between 16% and 43%. USNS COMFORT (TAH 20) treated nearly 95,000 patients in 2007 during an HA deployment; operational efficiencies can translate into thousands more benefiting from HA. This thesis also helps allocate helicopter flight hours, a monthly constraint, over a set of daily SSTP scenarios.http://archive.org/details/optimizingshipto109454153Outstanding ThesisUS Navy (USN) author.Approved for public release; distribution is unlimited
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Heavy-traffic extreme-value limits for queues
We consider the maximum waiting time among the first n customers in the GI/G/1 queue. We use strong approximations to prove, under regularity conditions, convergence of the normalized maximum wait to the Gumbel extreme-value distribution when the traffic intensity ρ approaches 1 from below and n approaches infinity at a suitable rate. The normalization depends on the interarrival-time and service-time distributions only through their first two moments, corresponding to the iterated limit in which first ρ approaches 1 and then n approaches infinity. We need n to approach infinity sufficiently fast so that n ( 1 − ρ )2 → ∞. We also need n to approach infinity sufficiently slowly: If the service time has a pth moment for ρ > 2, then it suffices for ( 1 − ρ ) n 1 / p to remain bounded; if the service time has a finite moment generating function, then it suffices to have ( 1 − ρ ) log n → 0. This limit can hold even when the normalized maximum waiting time fails to converge to the Gumbel distribution as n → ∞ for each fixed ρ. Similar limits hold for the queue length process
Visualizing War
Curators Andrew Egbert, Natalie Sherif, and Alexandra Ward have designed an experience that allows us to consider why these images resonated with such power for Civil War Americans. In doing so, they have shifted the gallery experience away from a truth-seeking mission, giving us instead a platform from which to move beyond questions of whether visual culture was realistic or not. They offer us a chance to explore the emotional and intellectual connections that sustained Americans long after the shouts and cheers in rushing to arms had faded. [excerpt]https://cupola.gettysburg.edu/artcatalogs/1008/thumbnail.jp
Structural Studies of Low Temperature Ice Iₕ Using a Central Force Potential Model
The revised central force potentials of Stillinger and Rahman [J. Chem. Phys. 68, 666 (1978)] are used to study the binding energy, structure, and multipole moments of a periodic ice Ih sample with a unit cell of 192 water molecules. The initial configuration for the unit cell has each oxygen in a wurtzite structure and intramolecular H-O-H angles symmetrically positioned in the tetrahedral O-O-O angles. Hydrogens are placed such that the total dipole moment for the unit cell is zero and the diagonal quadrupole moments are small (≲ 10-28 esu cm2). Subject to these restrictions, a static energy minimization on the periodic ice crystal yields an optimal O-O separation, intramolecular O-H distance, and intramolecular H-O-H angle of 2.78, 0.972 A, and 101.0°, respectively. Starting from this idealized wurtzite configuration, Metropolis Monte Carlo runs on the periodic system are made at 20 and 200 K. At 20 K, the equilibrated system has an average intermolecular potential energy per molecule of -15.2 kcal/mol and structure factors which have decreased to about 80% of the initial values. The dipole moment for the unit cell is ≃3 D. The equilibrated system at 200 K appears to be modified only by temperature dependent vibrational effects
Health specific traits beyond the Five Factor Model, cognitive processes and trait expression: replies to Watson (2012), Matthews (2012) and Haslam, Jetten, Reynolds, and Reicher (2012)
In this article we reply to the issues raised by the three commentaries on Ferguson's (2012) article. Watson argues that the four traits identified by Ferguson (2012) – health anxiety, alexithymia, empathy and Type D – do not lie outside the Five Factor Model (FFM). We present factor analytic data showing that health anxiety forms a separate factor from positive and negative affectivity, alexithymia forms a factor outside the FFM and while emotional empathy loads with agreeableness, cognitive empathy forms a separate factor outside the FFM. Across these analyses there was no evidence for a general factor of personality. We also show that health anxiety, empathic facets and alexithymia show incremental validity over FFM traits. However, the evidence that Type D lies outside the FFM is less clear. Matthews (2012) argues that traits have a more distributed influence on cognitions and that attention is not part of Ferguson's framework. We agree; but Ferguson's original statement concerned where traits have their maximal effect. Finally, Haslam et al. suggest that traits should be viewed from a dynamic interactionist perspective. This is in fact what Ferguson (2012) suggested and we go on to highlight that traits can also influence group processes
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Accountability and Transparency of Entrepreneurial Journalism: Unresolved ethical issues in crowdfunded journalism projects
Crowdfunding is a new business model in which journalists rely—and depend—on (micro-) payments by a large number of supporters to finance their reporting. In this form of entrepreneurial journalism the roles of publisher, fundraiser and journalist often overlap. This raises questions about conflicts of interest, accountability and transparency. The article presents the results of selected case studies in four different European countries—Germany (Krautreporter), Italy (Occhidellaguerra), the United Kingdom (Contributoria) and the Netherlands (De Correspondent)—as well as one US example (Kickstarter). The study used a two-step methodological approach: first a content analysis of the websites and the Twitter accounts with regard to practices of media accountability, transparency and user participation was undertaken. The aim was to investigate how far ethical challenges in crowdfunded entrepreneurial journalism are accounted for. Second, we present findings from semi-structured interviews with journalists from each crowdfunding. The study provides evidence about the ethical issues in this area, particularly in relation to production transparency and responsiveness. The study also shows that in some cases of crowdfunding (platforms), accountability is outsourced and implemented only through the audience participation
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