Letter from James B. Adams to R[obert] U[nderwood] Johnson, 1906 Aug 11.

UNITED STATES DEPARTMENT OF AGRICULTUREFOREST SERVICEWASHINGTONOFFICE OF THE FORESTERAugust 11, 1906.,br\u3eMr. R. U. Johnson,Associate Editor Century Magazine,Union Square, New York City,Dear sir:Your letter of August 9, addressed to Mr. Pinchot\u27s Secretary, is received in his absence.Mr. Lacey\u27s Bill to create The Petrified Forest National Park in Arizona failed to pass at the last session of Congress. It was reported from the House Committee with certain amendments, a copy of which, together with the report, I enclose for your information.Very truly yours,[illegible]Acting Forester.Enclosure.06409

Reliability and performance evaluation of systems containing embedded rule-based expert systems

A method for evaluating the reliability of real-time systems containing embedded rule-based expert systems is proposed and investigated. It is a three stage technique that addresses the impact of knowledge-base uncertainties on the performance of expert systems. In the first stage, a Markov reliability model of the system is developed which identifies the key performance parameters of the expert system. In the second stage, the evaluation method is used to determine the values of the expert system's key performance parameters. The performance parameters can be evaluated directly by using a probabilistic model of uncertainties in the knowledge-base or by using sensitivity analyses. In the third and final state, the performance parameters of the expert system are combined with performance parameters for other system components and subsystems to evaluate the reliability and performance of the complete system. The evaluation method is demonstrated in the context of a simple expert system used to supervise the performances of an FDI algorithm associated with an aircraft longitudinal flight-control system

Accelerated Hatching of Southern Leopard Frog (Rana sphenocephala) Eggs in Response to the Presence of a Crayfish (Procambarus nigrocinctus) Predator

Phenotypic plasticity, such as morphological and behavioral changes in response to predators, is common in larval anurans. Less is known about inducible defenses in the embryonic stages of development. We investigated the predation risk imposed by crayfish (Procambarus nigrocinctus) on southern leopard frog (Rana sphenocephala) eggs aud whether crayfish presence induces a change in the timing of hatching of R. sphenocephala eggs. We found that crayfish significantly reduce the hatching success of R. sphenocephala eggs by eating them and that eggs hatch significantly faster in the presence of crayfish than when crayfish are not present. We also found that the nonlethal presence of crayfish (caged with no access to eggs) induced accelerated hatching, indicating that injured conspecifics are not required to elicit the response. Reception of chemical cues produced or released by crayfish may play an important role in survival of R. sphenocephala eggs

The influence of predator threat on the timing of a life-history switch point: predator-induced hatching in the southern leopard frog (Rana sphenocephala)

We tested the hypotheses that potential egg predators, crayfish Procambarus nigrocinctus and dytiscid Cybister sp. larvae, would accelerate the timing of hatching and that a larval predator, dragonfly naiad Anax junius, would delay hatching in the southern leopard frog (Rana sphenocephala). We also tested the hypothesis that differences in response would be proportional to predator lethality. Our results indicate that our hypotheses were partially supported. The presence of an efficient egg predator (crayfish) induces hatching faster than a less efficient predator (dytiscid larvae). However, the presence of a larval predator (naiads) did not delay hatching. Eggs that developed in the presence of egg predators produced hatchlings that were shorter (total length) than those reared in the presence of larval predators or those reared in the absence of predators. We suggest that earlier hatching times should decrease vulnerability to egg predators but result in shorter hatchlings

Toward a descriptive model of galactic cosmic rays in the heliosphere

Researchers review the elements that enter into phenomenological models of the composition, energy spectra, and the spatial and temporal variations of galactic cosmic rays, including the so-called anomalous cosmic ray component. Starting from an existing model, designed to describe the behavior of cosmic rays in the near-Earth environment, researchers suggest possible updates and improvements to this model, and then propose a quantitative approach for extending such a model into other regions of the heliosphere

An Economic Comparison of Conventional and Narrow-Row Cotton Production--Southern Plains of Texas.

12 p