Undermining Indigenous Self-Determination and Land Access in Highland Peru

While current neoliberal privatisation laws provide for protections to indigenous lands, no formal or informal mechanisms exist for natives to actually enjoy such safeguards

Proximity Navigation of Highly Constrained Spacecraft

Bandit is a 3-kg automated spacecraft in development at Washington University in St. Louis. Bandit's primary mission is to demonstrate proximity navigation, including docking, around a 25-kg student-built host spacecraft. However, because of extreme constraints in mass, power and volume, traditional sensing and actuation methods are not available. In particular, Bandit carries only 8 fixed-magnitude cold-gas thrusters to control its 6 DOF motion. Bandit lacks true inertial sensing, and the ability to sense position relative to the host has error bounds that approach the size of the Bandit itself. Some of the navigation problems are addressed through an extremely robust, error-tolerant soft dock. In addition, we have identified a control methodology that performs well in this constrained environment: behavior-based velocity potential functions, which use a minimum-seeking method similar to Lyapunov functions. We have also adapted the discrete Kalman filter for use on Bandit for position estimation and have developed a similar measurement vs. propagation weighting algorithm for attitude estimation. This paper provides an overview of Bandit and describes the control and estimation approach. Results using our 6DOF flight simulator are provided, demonstrating that these methods show promise for flight use

Electoral Institutions, Ethnopolitical Cleavages, and Party Systems in Africa\u27s Emerging Democracies

Do electoral institutions and ethnopolitical cleavages shape the structure of party systems separately or jointly? We examine the independent, additive, and interactive effects on the number of electoral and legislative parties of two institutional variables (district magnitude and proximity of presidential and legislative elections), one intervening variable (effective number of presidential candidates), and two new measures of ethnopolitical cleavages based on constructivist specification of ethnopolitical groups (fragmentation and concentration). Ethnopolitical fragmentation independently reduces the number of parties but, interactively with ethnopolitical concentration, increases it. However, the additive and interactive combinations of both measures with electoral institutions explain the largest amount of variance in the number of parties. These results emphasize the importance of ethnopolitical cleavages in mediating the effects of electoral institutions on the structure of party systems, with important implications for the stability of Africa\u27s emerging democracies in which parties are weak and multiethnic coalitions are fluid

Advances in Orion's On-Orbit Guidance and Targeting System Architecture

NASA's manned spaceflight programs have a rich history of advancing onboard guidance and targeting technology. In order to support future missions, the guidance and targeting architecture for the Orion Multi-Purpose Crew Vehicle must be able to operate in complete autonomy, without any support from the ground. Orion's guidance and targeting system must be sufficiently flexible to easily adapt to a wide array of undecided future missions, yet also not cause an undue computational burden on the flight computer. This presents a unique design challenge from the perspective of both algorithm development and system architecture construction. The present work shows how Orion's guidance and targeting system addresses these challenges. On the algorithm side, the system advances the state-of-the-art by: (1) steering burns with a simple closed-loop guidance strategy based on Shuttle heritage, and (2) planning maneuvers with a cutting-edge two-level targeting routine. These algorithms are then placed into an architecture designed to leverage the advantages of each and ensure that they function in concert with one another. The resulting system is characterized by modularity and simplicity. As such, it is adaptable to the on-orbit phases of any future mission that Orion may attempt

An Autonomous Onboard Targeting Algorithm Using Finite Thrust Maneuvers

In earlier investigations, the adaptation and implementation of a modified two-level corrections process as the onboard targeting algorithm for the Trans-Earth Injection phase of Orion is presented. The objective of that targeting algorithm is to generate the times of ignition and magnitudes of the required maneuvers such that the desired state at entry interface is achieved. In an actual onboard flight software implementation, these times of ignition and maneuvers are relayed onto Flight Control for command and execution. Although this process works well when the burn durations or burn arcs are small, this might not be the case during a contingency situation when lower thrust engines are employed to perform the maneuvers. Therefore, a new version of the modified two-level corrections process is formulated to handle the case of finite burn arcs. This paper presents the development and formulation of that finite burn modified two-level corrections process which can again be used as an onboard targeting algorithm for the Trans-Earth Injection phase of Orion. Additionally, performance results and a comparison between the two methods are presented. The finite burn two-level corrector formulation presented here ensures the entry constraints at entry interface are still met without violating the available fuel budget, while still accounting for much longer burn times in its design

Encke-Beta Predictor for Orion Burn Targeting and Guidance

The state vector prediction algorithm selected for Orion on-board targeting and guidance is known as the Encke-Beta method. Encke-Beta uses a universal anomaly (beta) as the independent variable, valid for circular, elliptical, parabolic, and hyperbolic orbits. The variable, related to the change in eccentric anomaly, results in integration steps that cover smaller arcs of the trajectory at or near perigee, when velocity is higher. Some burns in the EM-1 and EM-2 mission plans are much longer than burns executed with the Apollo and Space Shuttle vehicles. Burn length, as well as hyperbolic trajectories, has driven the use of the Encke-Beta numerical predictor by the predictor/corrector guidance algorithm in place of legacy analytic thrust and gravity integrals

Investigation of Alternative Return Strategies for Orion Trans-earth Injection Design Options

The purpose of this study is to investigate alternative return strategies for the Orion trans-Earth injection (TEI) phase. A dynamical systems analysis approach considers the structure of the stable and unstable Sun perturbed Earth-Moon manifolds near the Earth-Moon interface region. A hybrid approach, then, combines the results from this analysis with classical two-body methods in a targeting process that seeks to expand the window of return opportunities in a precision entry scenario. The resulting startup arcs can be used, for instance, to enhance the block set of solutions available onboard during an autonomous targeting process

Political Competition and Ethnic Identification in Africa

This paper draws on data from over 35,000 respondents in twenty-two public opinion surveys in ten countries and finds strong evidence that ethnic identities in Africa are strengthened by exposure to political competition. In particular, for every month closer their country is to a competitive presidential election, survey respondents are 1.8 percentage points more likely to identify in ethnic terms. Using an innovative multinomial logit empirical methodology, we find that these shifts are accompanied by a corresponding reduction in the salience of occupational and class identities. Our findings lend support to situational theories of social identification and are consistent with the view that ethnic identities matter in Africa for instrumental reasons: because they are useful in the competition for political power

An Autonomous Onboard Targeting Algorithm Using Finite Thrust Maneuvers

In earlier investigations, the adaptation and implementation of a modified two-level corrections (or targeting) process as the onboard targeting algorithm for the Trans-Earth Injection phase of Orion is presented. The objective of that targeting algorithm is to generate the times of ignition and magnitudes of the required maneuvers such that the desired state at entry interface is achieved. In an actual onboard flight software implementation, these times of ignition and maneuvers are relayed onto Flight Control for command and execution. Although this process works well when the burn durations or burn arcs are small, this might not be the case during a contingency situation when lower thrust engines are employed to perform the maneuvers. Therefore, a new model for the two-level corrections process is formulated here to accommodate finite burn arcs. This paper presents the development and formulation of the finite burn two-level corrector, used as an onboard targeting algorithm for the Trans-Earth Injection phase of Orion. A performance comparison between the impulsive and finite burn models is also presented. The present formulation ensures all entry constraints are met, without violating the available fuel budget, while allowing for low-thrust scenarios with long burn durations

Macrophage phenotype in response to ECM bioscaffolds

Macrophage presence and phenotype are critical determinants of the healing response following injury. Downregulation of the pro-inflammatory macrophage phenotype has been associated with the therapeutic use of bioscaffolds composed of extracellular matrix (ECM), but phenotypic characterization of macrophages has typically been limited to small number of non-specific cell surface markers or expressed proteins. The present study determined the response of both primary murine bone marrow derived macrophages (BMDM) and a transformed human mononuclear cell line (THP-1 cells) to degradation products of two different, commonly used ECM bioscaffolds; urinary bladder matrix (UBM-ECM) and small intestinal submucosa (SIS-ECM). Quantified cell responses included gene expression, protein expression, commonly used cell surface markers, and functional assays. Results showed that the phenotype elicited by ECM exposure (MECM) is distinct from both the classically activated IFNγ + LPS phenotype and the alternatively activated IL-4 phenotype. Furthermore, the BMDM and THP-1 macrophages responded differently to identical stimuli, and UBM-ECM and SIS-ECM bioscaffolds induced similar, yet distinct phenotypic profiles. The results of this study not only characterized an MECM phenotype that has anti-inflammatory traits but also showed the risks and challenges of making conclusions about the role of macrophage mediated events without consideration of the source of macrophages and the limitations of individual cell markers