Algorithmic Analysis of Array-Accessing Programs

For programs whose data variables range over Boolean or finite domains, program verification is decidable, and this forms the basis of recent tools for software model checking. In this paper, we consider algorithmic verification of programs that use Boolean variables, and in addition, access a single array whose length is potentially unbounded, and whose elements range over pairs from Σ × D, where Σ is a finite alphabet and D is a potentially unbounded data domain. We show that the reachability problem, while undecidable in general, is (1) Pspace-complete for programs in which the array-accessing for-loops are not nested, (2) solvable in Ex-pspace for programs with arbitrarily nested loops if array elements range over a finite data domain, and (3) decidable for a restricted class of programs with doubly-nested loops. The third result establishes connections to automata and logics defining languages over data words

Genetic parameters, prediction of gains and intraspecific hybrid selection of Paspalum notatum Flügge for forage using REML/BLUP

Genetic improvement of native forage species is a sustainable alternative for maximizing livestock production. Paspalum notatum Flügge is the most important forage grass in the native grasslands of southern Brazil, with substantial potential available for further genetic improvement. The objective of this study was to quantify a range of genetic parameters and predict yield gains in a population of P. notatum intraspecific hybrids. Results indicated intraspecific hybrids of P. notatum had high magnitudes of heritability in the broad and average sense of genotype, plus high selective accuracy and genetic variation for all forage characteristics evaluated. This indicated REML/BLUP can contribute useful information for plant selection in future plant breeding programs. The genetic material studied showed high genetic variability for forage production. Analysis indicated hybrids 336, 332, 437, 132 and male parent '30N' should be included in new crosses to increase the dry matter production of P. notatum. Parents need to be selected from different groups in order to maximize genetic variability and heterosis. In addition, these parents must be included in diallel crosses. The results obtained in this study provide important information for the future breeding of improved P. notatum cultivars for commercialization

A process model of the formation of spatial presence experiences

In order to bridge interdisciplinary differences in Presence research and to establish connections between Presence and “older” concepts of psychology and communication, a theoretical model of the formation of Spatial Presence is proposed. It is applicable to the exposure to different media and intended to unify the existing efforts to develop a theory of Presence. The model includes assumptions about attention allocation, mental models, and involvement, and considers the role of media factors and user characteristics as well, thus incorporating much previous work. It is argued that a commonly accepted model of Spatial Presence is the only solution to secure further progress within the international, interdisciplinary and multiple-paradigm community of Presence research

Studies on iron availability in man, using stable isotope techniques

1. Iron absorption from 10 mg Fe (as ferrous sulphate), labelled with 1.3 mg 58Fe, was measured in fasting, non-anaemic adult subjects by the faecal-balance technique. The measurement was performed twice, each subject being given, in random order, either 50 mg Fe or a placebo 18 h before the 58Fe-labelled FeSO4. 2. The 50 mg Fe load significantly reduced Fe absorption the following day (P less than 0.01), from a mean of 35.4 (SEM 4.6)% to 29.0 (SEM 5.1)%. This points to the importance of strict dietary control during Fe-absorption studies to eliminate bias in results. 3. In a separate study, the feasibility of using 58Fe-enrichment of erythrocytes, measured by neutron activation analysis (NAA), 10 d after a meal labelled with 0.69 mg 58Fe as an index of Fe absorption was examined. The levels of 58Fe in the blood were detectable by NAA. Regression analysis showed a significant relation between 58Fe-enrichment of blood and 58Fe absorption, calculated as the difference between intake and faecal excretion (R 0.59, P less than 0.05)

Nonradioisotopic method for measuring iron absorption from a Gambian meal

Iron absorption from a typical Gambian meal of rice with groundnut sauce was measured by the fecal balance technique in nonanemic adult males with 58Fe as an extrinsic label and neutron activation analysis and compared with ferrous sulphate. Gambian men had a higher efficiency of absorption than UK volunteers but the availability of the food Fe was approximately half that of ferrous sulphate in both groups of subjects

Determination of silver in plants by flameless atomic absorption spectrometry and neutron activation analysis

Three analytical techniques suitable for determining silver concentrations in plants are presented and compared. Graphite furnace atomic absorption spectrometry performed directly on sample digests was the most sensitive and convenient. Neutron activation analysis, measuring 110mAg gave good reproducibility, but lower sensitivity. A cyclic activation scheme to generate and detect the short-lived isotope 110Ag was useful as a quick reconnaissance technique, but interference from 76As reduced its effectiveness. Data are presented on the silver content of terrestrial plants. Background silver concentrations for lichens and bryophytes collected from Wales, U.K. were 0.07μg g-1. Samples collected from areas contaminated by derelict metal mines contained between 0.1-1.0 μgAg g-1. The aerial portions of vascular species usually contained less silver than bryophytes growing on the same substrate. Fungi are shown to bioconcentrate silver to a greater extent than cadmium, copper or lead

Riboflavin deficiency and iron absorption in adult Gambian men

Iron absorption from 3.38 mg 58Fe was measured in riboflavin-deficient Gambian men with haemoglobin (Hb) less than 11.5 g/dl before and after oral riboflavin therapy, and the results compared with a group not receiving riboflavin. Riboflavin status (as determined by erythrocyte glutathione reductase activation coefficient) and Hb increased in teh riboflavin-supplemented but not placebo group. Plasma ferritin levels were low and did not change in either group. There was very wide variation in percentage iron absorption between individuals and also within single individuals on two separate occasions but no measurable change with riboflavin supplementation. The results of the study indicate that the efficiency of iron utilization is impaired in riboflavin deficiency, but that iron absorption is unaffected

Iron and zinc absorption in human subjects from a mixed meal of extruded and nonextruded wheat bran and flour

The effect of extrusion cooking of a bran-flour mixture on iron and zinc retention was measured in normal adults. The stable isotopes 58Fe (1.253 mg) and 67Zn (5.13 mg) were administered with 40 g nonextruded or extruded cereal with milk and isotopic retention was measured from fecal excretion over the next 4-7 d by neutron-activation analysis (Fe) and fast-atom-bombardment mass spectrometry (Zn). 58Fe retention was 15.1 +/- 2.4% (means +/- SEM) with the nonextruded meal and 16.5 +/- 2.7% with the extruded meal. 67Zn retention was 18.9 +/- 1.7% with the nonextruded meal and 18.3 +/- 1.5% with the extruded meal. Extrusion cooking had no effect on 58Fe or 67Zn retention