Petar Marković

We begin the investigation of the variety of semilattices of Mal?cev blocks, which we call SMB algebras.

We consider the quasilinear varieties of groupoids which were characterized in [4] and find the residual character for all of them. Those varieties which are residually small turn out to be residually finite. We compute the residual bounds and find all subdirectly irreducible algebras in them.

If ?R,E? is the Rado graph andR(R) the set of its copies inside R, then ?R(R), ?? is a chain-complete and non-atomic partial order of the size 2x0 . A family A ? R(R) is a maximal antichain in this partial order iff (1) A ? B does not contain a copy of R, for each different A, B ?A and (2) For each S ? R(R) there is A ? A such that A ? S contains a copy of R. We show that the partial order ?R(R), ?? contains maximal antichains of size 2x0, X0 and n, for each positive integer n (thus, of all possible cardinalities, under CH). The results are compared with the corresponding known results concerning the partial order ?[?]?, ??.

Introduction. Ultrastructural changes in corneas of patients with diabetes mellitus have been previously described. Objective. The aim of this study was to compare central corneal thickness (CDR) values in diabetic patients without retinopathy at the stage of diabetic nonproliferative and proliferative retinopathy and CDR in a control group of healthy subjects. Methods. The study included 121 diabetic patients and 125 healthy subjects matched according to gender and age. Each patient underwent ophthalmological examination involving a dilated fundus examination and CDR measurement using the ultrasound pachymeter. The eyes of diabetic patients were classified according to Early Treatment Diabetic Retinopathy Study into three groups: without diabetic retinopathy (NDR), with nonproliferative diabetic retinopathy (NPDR) and a group with proliferative diabetic retinopathy (PDR). Only one eye of each subject was chosen for the study. Results. The mean CDR value was significantly higher in the diabetic group (570.52?31.81 ?m) compared with the control group (541.42?27.82 ?m). The difference between the two groups was statistically significant (p<0.0001). The highest mean CDR value was recorded in the PDR group (585.97?28.58 ?m), followed by the NPDR group (570.84?30.27 ?m), whereas the lowest mean CDR value was recorded in the NDR group (559.80?31.55 ?m). There was a statistically significant difference in CDR between the NDR and PDR groups, as well as between the NPDR and PDR groups (p<0.001, p0.05). Conclusion. CDR of diabetic patients was higher compared to healthy subjects. The highest mean value of CDR was registered in the PDR group, followed by the NPDR and the NDR groups.