Lax matrices for Yang-Baxter maps

It is shown that for a certain class of Yang-Baxter maps (or set-theoretical solutions to the quantum Yang-Baxter equation) the Lax representation can be derived straight from the map itself. A similar phenomenon for 3D consistent equations on quad-graphs has been recently discovered by A. Bobenko and one of the authors, and by F. Nijhoff

The natural history of bugs: using formal methods to analyse software related failures in space missions

Space missions force engineers to make complex trade-offs between many different constraints including cost, mass, power, functionality and reliability. These constraints create a continual need to innovate. Many advances rely upon software, for instance to control and monitor the next generation ‘electron cyclotron resonance’ ion-drives for deep space missions.Programmers face numerous challenges. It is extremely difficult to conduct valid ground-based tests for the code used in space missions. Abstract models and simulations of satellites can be misleading. These issues are compounded by the use of ‘band-aid’ software to fix design mistakes and compromises in other aspects of space systems engineering. Programmers must often re-code missions in flight. This introduces considerable risks. It should, therefore, not be a surprise that so many space missions fail to achieve their objectives. The costs of failure are considerable. Small launch vehicles, such as the U.S. Pegasus system, cost around $18 million. Payloads range from$4 million up to $1 billion for security related satellites. These costs do not include consequent business losses. In 2005, Intelsat wrote off$73 million from the failure of a single uninsured satellite. It is clearly important that we learn as much as possible from those failures that do occur. The following pages examine the roles that formal methods might play in the analysis of software failures in space missions

Evaluation of an advanced directionally solidified gamma/gamma'-alpha Mo eutectic alloy

An attempt was made to improve on the properties of the candidate jet engine turbine blade material AG-60, a gamma/gamma prime-alpha Mo eutectic composite. Alloy 38 (AG-170) was evaluated in the greatest detail. This alloy, Ni-5.88 A1-29.74 Mo-1.65 V-1.2C Re (weight percent), represents an improvement beyond AG-60, based on mechanical testing of the transverse and/or longitudinal orientations over a range of temperatures in tension, shear, rupture, and rupture after thermal exposure. It is likely that other alloys in the study represent a similar improvement

Arkansas Cotton Variety Test 2003

The primary aim of the Arkansas Cotton Variety Test is to provide unbiased data regarding the agronomic performance of cotton varieties and advanced breeding lines in the major cotton-growing areas of Arkansas. This information helps seed dealers establish marketing strategies and assists producers in choosing varieties to plant. In this way, the annual test facilitates the inclusion of new, improved genetic material in Arkansas cotton production

Photoionization yield and absorption coeffi- cient of xenon in the region 860-1022 deg angstrom

Photoionization yield and absorption coefficient of xenon gas measured by photoelectric method

Helical Symmetry in Linear Systems

We investigate properties of solutions of the scalar wave equation and Maxwell's equations on Minkowski space with helical symmetry. Existence of local and global solutions with this symmetry is demonstrated with and without sources. The asymptotic properties of the solutions are analyzed. We show that the Newman--Penrose retarded and advanced scalars exhibit specific symmetries and generalized peeling properties.Comment: 11 page

Some Intensity Measurements in the Vacuum Ultraviolet

Intensity measurements in vacuum ultraviolet - photoelectric yields of untreated metals and semiconductors measured by calibrated thermocoupl

Is It a Jungle Out There? Meat Packing, Immigrants, and Rural Communities

The shift of the U.S. meat packing industry from urban to rural areas has generated controversy regarding potential social and economic costs of meat packing plants on their host communities. This study uses media comments to identify the most prominent controversies regarding meat packing, its largely immigrant workforce, and rural communities. We find that the industry has impacted the demographic composition of rural communities and their schools, but find no evidence that the industry increases per capita government expenditures. Our results suggest rural communities trade off the economic benefits of hosting these large employers against the costs of accommodating needs of new residents.immigration, meat packing, rural communities, Community/Rural/Urban Development, Livestock Production/Industries,

Random Walkers with Shrinking Steps in d-Dimensions and Their Long Term Memory

We study, in d-dimensions, the random walker with geometrically shrinking step sizes at each hop. We emphasize the integrated quantities such as expectation values, cumulants and moments rather than a direct study of the probability distribution. We develop a 1/d expansion technique and study various correlations of the first step to the position as ti me goes to infinity. We also show and substantiate with a study of the cumulants that to order 1/d the system admits a continuum counterpart equation which can be obtained with a generalization of the ordinary technique to obtain the continuum limit. We also advocate that this continuum counterpart equation, which is nothing but the ordinary diffusion equation with a diffusion constant decaying exponentially in continuous time, captures all the qualitative aspects of t he discrete system and is often a good starting point for quantitative approximations

A study of the angular size-redshift relation for models in which Λ\Lambda decays as the energy density

By modifying the Chen and Wu ansatz, we have investigated some Friedmann models in which $\Lambda$ varies as $\rho$. In order to test the consistency of the models with observations, we study the angular size - redshift relation for 256 ultracompact radio sources selected by Jackson and Dodgson. The angular sizes of these sources were determined by using very long-baseline interferometry in order to avoid any evolutionary effects. The models fit the data very well and require an accelerating universe with a positive cosmological constant. Open, flat and closed models are almost equally probable, though the open model provides a comparatively better fit to the data. The models are found to have intermediate density and imply the existence of dark matter, though not as much as in the canonical Einstein-de Sitter model.Comment: LaTex, 15 pages including 2 figures (Revised version appeared in CQG