Spatial distribution of bluetongue in cattle in southern Croatia in the last quarter of 2002.

The domestic ruminant population of southern Croatia was affected by bluetongue (BT) in late 2001. A sentinel cattle scheme was developed to detect the presence of bluetongue virus (BTV) activity in the domestic cattle population in the protection zone (based on the distribution of BT in 2001: Dubrovacko-Neretvanska County and the southern area of the Splitsko-Dalmatinska County) as well as in the surveillance zone (the northern area of the Splitsko-Dalmatinska County). Twenty-five villages were selected to serve as sentinel locations during the observation period which lasted from 15 September to 15 December 2002. Seroconversion was not detected in cattle in sentinel locations in the surveillance zone. However, in the protection zone, serum antibodies to BTV serotype 9 were detected in eight cattle in five of the ten sentinel locations. Although no clinical case of BT disease was detected in sheep on mainland Croatia in late 2002, BTV activity was present in sentinel cattle in the protection zone. When compared with 2001, spatial distribution of the locations in which cattle seroconverted to BTV-9 in the last quarter of the 2002 suggests a northward trend to the spread of BTV in the cattle of southern Croatia.

Criticality of D=2 and D=3 Ising models: cluster structure versus populations.

The energy and the specific heat of two- and three-dimensional Ising systems are analyzed in terms of cluster properties. The energy and the specific heat are decomposed into two components, which are defined by quantities pertaining to cluster populations and cluster structure expressed in terms of average cluster perimeters. It is shown that the structural component of the energy as well as of the specific heat represents the dominant contribution. Indications are presented that the critical exponent of structural and populational components of specific heat matches the exponent of the entire specific heat.

Tandemly repeated pentanucleotides in DNA sequences of eucaryotes.

Genetic sequence data banks were scanned in order to retrieve tandemly repeated pentanucleotides (pnts). It was found that among 102 (=(1024-4)/2/5) possible distinct pnts roughly each fourth is involved in tandem repeats. It is shown that tandemly repeated pnts are composed of frequently occurring di- and trinucleotides and that those pnts which occur frequently in the form of mono- or di-pnts form also tandem repeats either in the form of satellites or in the form of shorter tandem repeats. Human satellite III is taken as a specific example. It is shown that the first guanine within GG-AAT pnt exhibits the highest mutability. Sequential distribution of base changes gives evidence that the mutations do not occur at random positions but in a correlated fashion so that long stretches of original pnts remain intact. It is found that pnts related to the satellite III are present in introns and flanking regions of some structural genes, but are not preserved between orthologous genes of related species. The results corroborate the most plausible mechanism of their evolution--rapid amplification followed by successive divergence of repeat units by various mutational processes.

Knowledge-based schedule formulation and maintenance under uncertainty.

This paper is concerned with the dual sequential problems of (1) determining an acceptable personnel schedule over a specified time period, and (2) adjusting that schedule during the course of its execution in reaction to daily changes in both demand and available personnel. The first problem is schedule formulation; the second sequential problem is schedule execution. A rule-based, hierarchical system has been developed for first modeling and then solving both the schedule formulation and the schedule execution problems as a two-phase dependent process. The system is applied to the scheduling and staffing of nurses. A double-blind evaluation was conducted, which ascertained the quality of the resultant schedules in terms of maintainability, coverage, and personal satisfaction. The evaluation indicates that for units on which personnel changes have occurred, the prototype appears to perform as well as human schedulers.