Application of covering techniques to families of curves

Much success in finding rational points on curves has been obtained by using Chabauty's Theorem, which applies when the genus of a curve is greater than the rank of the Mordell-Weil group of the Jacobian. When Chabauty's Theorem does not directly apply to a curve C, a recent modification has been to cover the rational points on C by those on a covering collection of curves D$_i$, obtained by pullbacks along an isogeny to the Jacobian; one then hopes that Chabauty's Theorem applies to each D$_i$. So far, this latter technique has been applied to isolated examples. We apply, for the first time, certain covering techniques to infinite families of curves. We find an infinite family of curves to which Chabauty's Theorem is not applicable, but which can be solved using bielliptic covers, and other infinite families of curves which even resist solution by bielliptic covers. A fringe benefit is an infinite family of Abelian surfaces with non-trivial elements of the Tate-Shafarevich group killed by a bielliptic isogeny

Florence Valley : An Abandoned Stream Valley, Florence Township, Erie County, Ohio

Author Institution: U.S.D.A. Soil Conservation Service, Sandusky, OhioAn abandoned stream valley, here called Florence Valley, was found in eastern Erie County, Ohio. Florence Valley is about one mile long and connects the valleys of Chappel Creek and the Vermilion River. There is evidence that Florence Valley was formed as a result of the capture of a tributary of the Vermilion River by Chappel Creek. Chappel Creek, at the junction of Florence Valley and the valley of Chappel Creek, has a rightangled bend, which displays morphology characteristic of an "elbow-of-capture." The gradient of the eastern two-thirds of Florence Valley slopes toward the Vermilion River. Because the Vermilion River is more deeply entrenched than is Chappel Creek, this stream capture must have taken place at a time when the base level was at a higher elevation, when Chappel Creek had a shorter course and steeper gradient than did the Vermilion River. These conditions are believed to have existed during the time of Lake Maumee III

Computer recommendations for an automatic approach and landing system for V/STOL aircraft. Volume 2 - Equations

Automatic approach and landing system for V/STOL aircraf

Australian SMEs waste to landfill

Landfill waste has a negative impact on the environment and small and medium sized enterprises (SMEs) are believed to be significant contributors. There is little government or scholarly research, however, quantifying the collective volume of waste SMEs send to landfill. Where studies do exist they measure total volumes (landfill and recycling combined) and/or do not distinguish between specific waste streams (e.g. wood) and subcategories (e.g. dust). This paper contributes to knowledge by giving insight into the collective volume of waste of 404 SMEs, reconceptualising SME waste into subcategories and by measuring landfill volumes. It presents findings from these 404 Australian SMEs which found that, in descending order, cardboard, paper, plastic wrap, wood dust and particleboard were the subcategories these SMEs sent to landfill in the greatest volumes. It also argues that this reconceptualisation, and associated data collection protocols, have the potential to enable scholars and policy makers to determine the waste subcategories to which SMEs contribute most, formulate targeted interventions and research or evaluate environmental outcomes. © 2014 © 2014 Environment Institute of Australia and New Zealand Inc

Dirac Cat States in Relativistic Landau Levels

We show that a relativistic version of Schrodinger cat states, here called Dirac cat states, can be built in relativistic Landau levels when an external magnetic field couples to a relativistic spin 1/2 charged particle. Under suitable initial conditions, the associated Dirac equation produces unitarily Dirac cat states involving the orbital quanta of the particle in a well defined mesoscopic regime. We demonstrate that the proposed Dirac cat states have a purely relativistic origin and cease to exist in the non-relativistic limit. In this manner, we expect to open relativistic quantum mechanics to the rich structures of quantum optics and quantum information.Comment: Revtex4, color figures, submitted for publicatio

Working together: the roles of geographic proximity, homophilic organizational characteristics, and neighborhood context in civic stewardship collaboration networks in Philadelphia and New York City

This is the final version. Available from Resilience Alliance via the DOI in this record. We examine networks of collaboration among civic environmental stewardship organizations in Philadelphia and New York City to understand which factors shape collaborative ties between organizations. Environmental issues in cities are increasingly complicated and often involve many actors, including citizens, governments, and organizations. Organizations frequently collaborate to tackle collective action problems related to environmental management. Here, we study two such networks collected as part of the U.S. Forest Service’s Stewardship Mapping and Assessment (STEW-MAP) project that monitors and maps the organizational characteristics of local environmental groups. We apply Exponential Random Graph models to demonstrate that network motifs, spatial proximity, organizational attributes, neighborhood context, and main issue focus all play different roles in explaining organizational collaboration among civic groups, but in very different ways across the two cities. Our findings reveal that civic networks are more correlated with homophily by social issues in Philadelphia, whereas civic networks in New York City are often correlated with geography proximity and homophily in land use. The comparative framework, still relatively rare in studies of environmental stewardship organizations, shows that different types of homophily, corresponding to different theoretical motivations, are at work in these cities. We conclude with some speculation as to the causes of these differences and their implications.US Forest Agenc

Waiting for Godot or sorting it now?

Postgraduate business education has become a very important financial stream for most tertiary institutions. However, what is becoming increasingly evident is that the assumption of good or even adequate academic competence, based on IELTS scores, is incorrect and that in reality many international students struggle to meet the academic standards and expectations of the overseas universities. This manifests itself in many ways; ultimately students fail units and have negative learning experiences. At best they reflect competencies of surface learners rather than those of deep learners. This paper reports on interim results of a pilot study that embedded an academic skills component into an introductory management unit in a MBA program. Based on the students’ plagiarism scores, the results to date demonstrate a positive outcome of the intervention. The students were found to have a significantly lower rate of plagiarism compared with a previous cohort. The pilot study highlights the need for more personal face-to-face help rather than impersonal cyber help and that when it comes to student learning, the ever increasing use of technology is misguided and over used as the salve for all problems

Charge transport in a CoPt3 nanocrystal microwire

The electrical characteristics of single CoPt3 nanocrystal microwires formed by magnetic field-directed growth from colloidal solutions are presented. The wires comprise disordered assemblies of discrete nanocrystals, separated from each other by protective organic ligand shells. Electrical data indicate that the activated charge transport properties of the wires are determined by the nanocrystal charging energy, governed by the size and capacitance of the individual nanocrystals. Focused ion beam-assisted deposition of Pt metal at the wire-electrode junctions is employed to optimize the wire-electrode contacts, whilst maintaining the nanocrystal-dominated transport characteristics of these one-dimensional nanocrystal structures. (C) 2004 American Institute of Physics. (DOI:10.1063/1.1830684