Generic Arc Research Articles

The Devil in the Machine: The Doctor Travels through Time in Chris Bush’s Faustus: That Damned Woman

Chris Bush’s Faustus: That Damned Woman (first performed in 2020) is a feminist and contemporary adaptation of Christopher Marlowe’s Doctor Faustus. The magus is a woman who travels through time from the seventeenth century to the far distant future. In the process, Johanna Faustus becomes a brilliant scientist who attempts to create digital immortality by uploading the minds of billions of human beings to the Cloud. When a power failure destroys almost all of humanity, it is uncertain whether the universal outage is caused by Mephistopheles (in accordance with the expectations of Faustian fantasy) or is simply an unforeseen but predictable accident (in accordance with the expectations of technophobic versions of science fiction). I argue that Bush’s play traces the chronological and generic arc from magic/fantasy to science/science fiction, blending the two so that the age-old monster, the Devil, enabled by Faustian arrogance, is reimagined as an avatar for an unreliable technology that destroys what it is designed to preserve.

Deformations of arcs and comparison of formal neighborhoods for a curve singularity

Abstract Let $ {\mathcal C} $ be an algebraic curve and c be an analytically irreducible singular point of ${\mathcal C}$ . The set ${\mathscr {L}_{\infty }}({\mathcal C})^c$ of arcs with origin c is an irreducible closed subset of the space of arcs on ${\mathcal C}$ . We obtain a presentation of the formal neighborhood of the generic point of this set which can be interpreted in terms of deformations of the generic arc defined by this point. This allows us to deduce a strong connection between the aforementioned formal neighborhood and the formal neighborhood in the arc space of any primitive parametrization of the singularity c. This may be interpreted as the fact that analytically along ${\mathscr {L}_{\infty }}({\mathcal C})^c$ the arc space is a product of a finite dimensional singularity and an infinite dimensional affine space.

Improved Monte Carlo Tree Search-based approach to low-thrust multiple gravity-assist trajectory design

In the preliminary design of low-thrust trajectories with multiple gravity-assist phases, the selection of the celestial bodies to be considered and the sequence of optimal maneuvers have a significant impact on the overall mission performance. This aspect makes the preliminary transfer trajectory analysis a very complex task. This Short Communication presents a novel method to design heliocentric multiple gravity-assist transfer trajectories for a spacecraft with a low-thrust propulsion system, where the total velocity variation is minimized. In this context, a Bézier shape-based method is used to describe the generic arc of a propelled trajectory, while an extension of the Monte Carlo Tree Search algorithm is used for a rapid analysis of the gravity-assist maneuver sequence. In particular, the proposed approach effectively solves the problem of selecting a suitable balance parameter in the Monte Carlo Tree Search-based routines, which makes the method especially useful in a preliminary mission phase. The effectiveness of the proposed approach is shown by simulating an interplanetary transfer towards the outer regions of the Solar System.

Total body irradiation for standard treatment rooms: a robust sweeping beam technique with respect to the body shape.

BackgroundThe purpose of this work is to improve a sweeping beam technique for total body irradiation (TBI) on a low flat couch using a varying patient thickness model. We designed a flat couch for total body irradiation in supine and prone position. Three generic arcs with rectangular segments for a patient torso thickness of 16, 22 and 28 cm were generated with respect to varying patient thickness of four particular parts of the body: head, torso, thighs and calves.Materials and methodsLongitudinal and transversal dose profiles were measured using an ionization chamber and the EBT3 gafchromic film in a solid water slab phantom. The robustness of the method was examined in phantoms of different thicknesses.ResultsMeasured dose homogeneity stays within ±10% of prescribed dose for all of the three patient thickness models. The robustness of the method was evaluated as the increase in dose in the phantom center of 0.7% per 1 cm reduction in phantom thickness.ConclusionThe method is applicable for the broad range of patient sizes, comfortable for patients, robust and suitable for standard treatment rooms with a standard linear accelerator. It requires minimal investments into equipment.

“…And that’s why I Teach For America”: American education reform and the role of redemptive stories

AbstractThis article interrogates the discursive relationship between school reform and redemption in the United States by examining the personal narratives of Teach For America corps members. After tracing the history of Teach For America and describing the rites of passage in which teachers’ “redemptive stories” are told, I analyze the generic arc that underlies them and show that it mirrors broader processes of in-group socialization. In doing so, I argue that Teach For America’s brand of redemptive storytelling – in addition to crafting individual identity, contributing to group cohesion, and enlivening performance at ritualized events – also affects organizational authority. As corps members master their stories of reform and redemption, paralleling the path to becoming “master teachers,” they participate in a process of “becoming” that reproduces in micro-scale the maturation of Teach For America. More profoundly, these transformations represent a distinct response to traditions of American confessional storytelling and the accountability-based education movement. Redemptive stories thus bind the socialization of the individual reformer to issues afoot more broadly in the province of education policy.

Arc therapy for total body irradiation – A robust novel treatment technique for standard treatment rooms

Background and purposeWe developed a simple and robust total body irradiation (TBI) method for standard treatment rooms that obviates the need for patient translation devices. Methods and materialsTwo generic arcs with rectangular segments for a patient thickness of 16 and 20cm (arc16/arc20) were generated. An analytical fit was performed to determine the weights of the arc segments depending on patient thickness and gantry angle. Stability and absolute dose for both arcs were measured using EBT3 films in a range of solid water slab phantom thicknesses. Additionally ionization chamber measurements were performed every 10cm at a source surface distance (SSD) of ∼200cm. ResultsThe measured standard deviation for arc16 is ±3% with a flatness ⩽9.0%. Arc20 had a standard deviation of ±3% with a flatness ⩽7.3% for all measured thicknesses. The theoretical curves proved to be accurate for the prediction of the segment weightings for the two arcs. In vivo measurements for the first 22 clinical patients showed a dose deviation of less than 3%. ConclusionsArc therapy is a convenient and stable method for TBI. This cost-effective approach has been introduced clinically, obviating the need for field patches and to physically move the patient.

Nash problem for surface singularities is a topological problem

We address Nash problem for surface singularities using wedges. We give a refinement of the characterisation in A. Reguera-López (2006) [32] of the image of the Nash map in terms of wedges. Our improvement consists in a characterisation of the bijectivity of the Nash mapping using wedges defined over the base field, which are convergent if the base field is C, and whose generic arc has transverse lifting to the exceptional divisor. This improves the results of M. Lejeune-Jalabert and A. Reguera (2008) [16] for the surface case. In the way to do this we find a reformulation of Nash problem in terms of branched covers of normal surface singularities. As a corollary of this reformulation we prove that the image of the Nash mapping is characterised by the combinatorics of a resolution of the singularity, or, what is the same, by the topology of the abstract link of the singularity in the complex analytic case. Using these results we prove several reductions of the Nash problem, the most notable being that, if Nash problem is true for singularities having rational homology sphere links, then it is true in general.

A Customization of the Arc Marine Data Model to Support Whale Tracking via Satellite Telemetry

AbstractThe Arc Marine data model is a generalized template to guide the implementation of geographic information systems (GIS) projects in the marine environment. It developed out of a collaborative process involving research and industry shareholders in coastal and marine research. This template models and attempts to standardize common ocean and coastal data types to facilitate data sharing and analytical tool development. In this study, Arc Marine is extended from its core model to fit the research goals of the whale satellite‐telemetry‐tagging program of the Oregon State University Marine Mammal Institute (MMI). The study sought the best customization of the generic Arc Marine data model to enhance the key advantages of satellite telemetry for mapping the distribution and movement of endangered marine mammal species. It was found that three new groups of object classes were needed (Animal, Telemetry, and Operations). Further customization involved the development of a comprehensive framework for animal tracking with Argos satellite telemetry data. A new multidimensional data cube model was also devised, showing how this extension of Arc Marine serves as an appropriate target schema for the application of on‐line analytical processing (OLAP) tools and spatial data mining of satellite telemetry tracking datasets.

Families of higher dimensional germs with bijective Nash map

Let (X,0) be a germ of complex analytic normal variety, non-singular outside 0. An essential divisor over (X,0) is a divisorial valuation of the field of meromorphic functions on (X,0), whose center on any resolution of the germ is an irreducible component of the exceptional locus. The Nash map associates to each irreducible component of the space of arcs through 0 on X the unique essential divisor intersected by the strict transform of the generic arc in the component. Nash proved its injectivity and asked if it was bijective. We prove that this is the case if there exists a divisorial resolution π of (X,0) such that its reduced exceptional divisor carries sufficiently many π-ample divisors (in a sense we define). Then we apply this criterion to construct an infinite number of families of 3-dimensional examples, which are not analytically isomorphic to germs of toric 3-folds (the only class of normal 3-fold germs with bijective Nash map known before).

Stability of quasi-transversal bifurcation of vector fields on 3-manifolds

Stability of generic arcs of hyperbolic vector fields having a bifurcation due to the creation of a quasi-transversal intersection orbit is studied under the assumption that The main novelty is the treatment that we give to the case where this quasi-transversal orbit is in the intersection of the unstable manifold of some orbit of a non-trivial basic set: we prove its stability using some special neighbourhood structure that resembles Thurston's `train tracks'. Following closely the ideas of Palis and Smale, our approach also provides a direct geometric proof of the stability of hyperbolic flows satisfying the transversality condition, a fact proved in all dimensions by Robinson. This original geometric approach has played a key role in the study of bifurcation and stability of parametrized families of vector fields as described by several authors.

Persistence of cycles and nonhyperbolic dynamics at heteroclinic bifurcations

We construct an open set A of arcs of diffeomorphisms bifurcating through the creation of heterodimensional cycles (i.e. there are points in the cycle having different indices) being robustly nonhyperbolic after the unfolding of the cycle: every diffeomorphism is not hyperbolic. We also prove that the arcs in A exhibit cycles persistently. Finally, for generic arcs in A and for a full (Lebesgue) set of parameters values we prove that the resulting nonwandering set is transitive and local maximal.