Shuttle orbiter S-band quad antenna switching evaluation

Automatic switching of the shuttle orbiter S-band quad antennas by the orbiter on-board computers was evaluated. The development and use of an extensive computer program to determine antenna switch position states as a function of time for various orbital activities is described. The selection of the optimum quad antenna element at any given time is based on the look angle to the appropriate Tracking Data Relay Satellite (TDRS). It is shown that a 2.4 second period is required for updating the S-band quad antenna switch state based on a maximum roll rate of 2 deg per second. The possibility of a variable update period is suggested since the 2 deg per second attitude rate is seldom encountered and would, for example, dictate approximately 248,000 on-board computer calculations during Reference Mission 2. The average number of antenna switch state changes was found to be in the range of 1,300 for Reference Mission 2

Number of adaptive steps to a local fitness peak

We consider a population of genotype sequences evolving on a rugged fitness landscape with many local fitness peaks. The population walks uphill until it encounters a local fitness maximum. We find that the statistical properties of the walk length depend on whether the underlying fitness distribution has a finite mean. If the mean is finite, all the walk length cumulants grow with the sequence length but approach a constant otherwise. Experimental implications of our analytical results are also discussed

Smallholder value chains as complex adaptive systems: a conceptual framework

Conventional analyses of value chains involving smallholders and the design of interventions that seek to strengthen their role in them often fail to account for important features of value chain performance. Markets, institutional frameworks and business relationships are dynamic, and value chain performance varies accordingly. Shocks and sudden changes occur frequently and require successful adaptation. This paper develops an expanded conceptual framework to understand value chain performance based on the theory of complex adaptive systems. The framework combines seven common properties of complex systems: time, uncertainty, sensitivity to initial conditions, endogenous shocks, sudden change, interacting agents and adaptation. We outline how the framework can be used to ask new research questions, analyse case studies, and develop new tools to increase the ability for enhanced risk management and adaptation

Description and Quality of Some Mango Varieties Grown in Hawaii and Their Suitability for Freezing

Quick-freezing of Hawaii fruits is a comparatively new process in the Islands, and much work is needed to determine the methods that will provide products of high quality. Mangos grow on all the Hawaiian Islands, but not all varieties are available on every island. Since 1949, this laboratory has frozen all of the superior named mango varieties obtainable (unknown seedlings were not included), varying the treatment and type of product, and testing the frozen samples after different periods of storage. This paper presents the descriptions of 21 Hawaii varieties of mangos and the results of freezing tests (for 20 varieties) for two seasons

Linear waves in sheared flows. Lower bound of the vorticity growth and propagation discontinuities in the parameters space

This study provides sufficient conditions for the temporal monotonic decay of enstrophy for two-dimensional perturbations traveling in the incompressible, viscous, plane Poiseuille and Couette flows. Extension of J. L. Synge's procedure (1938) to the initial-value problem allowed us to find the region of the wavenumber-Reynolds number map where the enstrophy of any initial disturbance cannot grow. This region is wider than the kinetic energy's one. We also show that the parameters space is split in two regions with clearly distinct propagation and dispersion properties

Response to a rabies epidemic in Bali, Indonesia

Emergency vaccinations and culling failed to contain an outbreak of rabies in Bali, Indonesia, during 2008–2009. Subsequent island-wide mass vaccination (reaching 70% coverage, >200,000 dogs) led to substantial declines in rabies incidence and spread. However, the incidence of dog bites remains high, and repeat campaigns are necessary to eliminate rabies in Bali

An Accurate Metabolic Simulator for Indirect Calorimetry System Validation

A metabolic simulator capable of simulation of respiratory oxygen consumption (VO2) and carbon dioxide production (VCO2) for validation of indirect calorimetry systems is described. The metabolic simulator adds/removes respiratory gases by way of mass flow controllers to/from a physiologically realistic lung simulator (Michigan Instruments Inc. Training/Test Lung). The metabolic simulator and Michigan Instruments Training/Test Lung in combination are capable of simulating a wide range of metabolic and physiologic lung conditions. Simulation of VCO2 is achieved by adding controlled amounts of carbon dioxide to the Training/Test Lung every (mechanical ventilator delivered) breath cycle. VO2 simulation consists of adding controlled amounts of nitrogen and removing controlled amounts of inspiratory gas from the Training/Test Lung every breath. Real time monitoring of ventilation parameters is obtained from a Novametrix Cosmo+ respiratory profile monitor and control of gas flow through the simulator is achieved by way of a programmed IBM personal computer

Rainfall and Grazing Impacts on the Population Dynamics of Bothriochloa Ewartiana in Tropical Australia

Bothriochloa ewartiana (desert bluegrass) is a palatable, native perennial (C4) grass of considerable importance to the northern Australian grazing industry. However, little is known of the interaction between grazing pressure and the highly variable rainfall found in this area, on its population dynamics. This paper reports interim results (1998-2004) from a long-term study, in which its population dynamics were examined under 3 grazing strategies