On the response to ocean surface currents in synthetic aperture radar imagery

The balance of wave action spectral density for a fixed wave-number is expressed in terms of a new dimensionless function, the degree of saturation, b, and is applied to an analysis of the variations of this quantity (and local spectral level) at wave-numbers large compared to that of the spectral peak, that are produced by variations in the ocean surface currents in the presence of wind input and wave breaking. Particular care is taken to provide physically based representations of wind input and loss by wave breaking and a relatively convenient equation is derived that specifies the distribution of the degree of saturation in a current field, relative to its ambient (undisturbed) background in the absence of currents. The magnitude of the variations in b depends on two parameters, U(o)/c, where U/(o) is the velocity scale of the current and c the phase speed of the surface waves at the (fixed) wave-number considered or sampled by SAR, and S = (L/lambda) (u*/c)(2), where L is the length scale of the current distribution, lambda the wavelength of the surface waves the length scale of the current distribution, lambda the wavelength of the surface waves and u* the friction velocity of the wind

Peace and goodwill? Using an experimental game to analyse Paz y Desarrollo

Several decades of conflict, rebellion and unrest severely weakened civil society in parts of Colombia. Paz y Desarrollo is the umbrella term used to describe the set of locally-led initiatives that aim at addressing this problem through initiatives to promote sustainable economic development and community cohesion and action. This project analyses the findings from a series of "public goods" games that were conducted in the spring and winter of 2006 in 103 municipalities in rural and urban Colombia with predominantly poor participants. These municipalities included both those with and without Paz y Desarrollo in place, and within those municipalities where it was ("treatment" municipalities), both individuals who are participants in the programme and those who are not. The municipalities where PYD is not in place ("control" municipalities) were surveyed as part of the evaluation of another programme - Familias en Accion (FEA), and this project also analyses the impact of this programme on game-play. The game is structured as a typical free-rider problem with the act of contributing to the "public good" (a collective money pot) being always dominated by non-contribution. We interpret contribution as an act consistent with a high degree of social capital. We find weak evidence that the programme acts at the group level: game sessions involving programme participants have higher levels of contribution than those not involving participants. In addition, there is some evidence that intensity of the programme matters: the more participants, the larger the impact. However, there is no evidence that the programme impacts at the individual level with participants no more likely to contribute than non-participants in treatment areas

(Dis)Continuities of custom in Zimbabwe and South Africa: the implications for gendered and sexual rights

This article historicizes the legal regulation of sexuality and claims to sexual rights in South Africa and Zimbabwe, analyzing their implications. Focusing on the interaction of formal Constitutions and informal customary law in the differential development of agency and rights, it highlights the constancy of women's partial legal subjectivity alongside shifts in authority from lineage to nation-state. The tensions between the legal formalism of rights, and the historical authority of customary structures buttress the regulation of sex and the claims to sexual rights within these two countries, and they frame a discussion of how sexualhealth programs and policies might better engage with the development of sexual agency

A comprehensive WebCT integration system

Murdoch University, in collaboration with industry partners, has developed a sophisticated middleware application (WebCTMan) between WebCT and other corporate systems, such as the Callista student records system, the Concept 1 human resources system and Murdoch’s own authentication system. This presentation will describe the architecture and functionality of this system. The impetus for WebCTMan was to enable Murdoch to change its student records database with minimal impact on our WebCT installation. However, WebCTMan now gives us great flexibility in managing our WebCT installation, enabling us to manage courses across teaching periods, and upgrade easily. This paper describes the context in which this system was built and gives an overview of its architecture. Courses in WebCTMan can have a status of active (where student details are updated nightly), inactive (where all students are orphans), and static (where student accounts are valid but not updated). Tools are available to change this status, and easily activate and deactivate courses. Different versions of courses are maintained for each teaching period, resolving the problem of overlap between semesters, when some students still have deferred examinations after the start of a new semester. In addition to managing students, WebCTMan provides functionality to manage staff and courses. Staff can request courses to be created or cloned from other courses. They can also create their own guest accounts and allocate tutors and markers to courses, and download class lists. Operators can create or rename courses on demand, as well as changing the roles of staff, including primary and secondary designers. A subset of functions is available to helpdesk operators, who can lookup details of both students and staff within the system

The Traveling Salesman Problem in the Natural Environment

Is it possible for humans to navigate in the natural environment wherein the path taken between various destinations is 'optimal' in some way? In the domain of optimization this challenge is traditionally framed as the "Traveling Salesman Problem" (TSP). What strategies and ecological considerations are plausible for human navigation? When given a two-dimensional map-like presentation of the destinations, participants solve this optimization exceptionally well (only 2-3% longer than optimum)^1, 2^. In the following experiments we investigate the effect of effort and its environmental affordance on navigation decisions when humans solve the TSP in the natural environment. Fifteen locations were marked on two outdoor landscapes with flat and varied terrains respectively. Performance in the flat-field condition was excellent (∼6% error) and was worse but still quite good in the variable-terrain condition (∼20% error), suggesting participants do not globally pre-plan routes but rather develop them on the fly. We suggest that perceived effort guides participant solutions due to the dynamic constraints of effortful locomotion and obstacle avoidance

Results of an experimental program to provide low cost computer searches of the NASA information file to university graduate students in the southeast Final report

Experimental program to provide low cost computer searches of NASA information files to university graduate student

Dislocation plasticity in thin metal films

This article describes the current level of understanding of dislocation plasticity in thin films and small structures in which the film or structure dimension plays an important role. Experimental observations of the deformation behavior of thin films, including mechanical testing as well as electron microscopy studies, will be discussed in light of theoretical models and dislocation simulations. In particular, the potential of applying strain-gradient plasticity theory to thin-film deformation is discussed. Although the results of all studies presented follow a “smaller is stronger” trend, a clear functional dependence has not yet been established

Mottness: Identifying the Propagating Charge Modes in doped Mott Insulators

High-temperature superconductivity in the copper-oxide ceramics remains an unsolved problem because we do not know what the propagating degrees of freedom are in the normal state. As a result, we do not know what are the weakly interacting degrees of freedom which pair up to form the superconducting condensate. That the electrons are not the propagating degrees of freedom in the cuprates is seen most directly from experiments that show spectral weight redistributions over all energy scales. Of course, the actual propagating degrees of freedom minimize such spectral rearrangements. This review focuses on the range of epxerimental consequences such UV-IR mixings have on the normal state of the cuprates, such as the pseudogap, mid-infrared band, temperature dependence of the Hall number, the superfluid density, and a recent theoretical advance which permits the identification of the weakly interacting degrees of freedom in a doped Mott insulator. Within this theory, we show how the wide range of phenomena which typify the normal state of the cuprates arises including $T-$linear resistivity.Comment: To appear as a Colloquium in the April issue of Rev. Mod. Phys Updated version contains new references and a clarification concerning Fig. 8

A Hot Microflare Observed With RHESSI and Hinode

RHESSI and Hinode observations of a GOES B-class flare are combined to investigate the origin of 15 MK plasma. The absence of any detectable hard X-ray emission coupled with weak blueshifted emission lines (indicating upward velocities averaging only 14 km/s) suggests that this was a result of direct heating in the corona, as opposed to nonthermal electron precipitation causing chromospheric evaporation. These findings are in agreement with a recent hydrodynamical simulation of microflare plasmas which found that higher temperatures can be attained when less energy is used to accelerate electrons out of the thermal distribution. In addition, unusual redshifts in the 2 MK Fe XV line (indicating downward velocities of 14 km/s) were observed cospatial with one of the flare ribbons during the event. Downflows of such high temperature plasma are not predicted by any common flare model.Comment: 6 pages, 4 figures, ApJL (Accepted