For topological spaces X, various special families of covers have been extensively studied in the literature, in a framework called selection principles, see the surveys [8, 4, 12]. The main types of covers are defined as follows. Let U be a cover of X. We say that U is a large (respectively, ω-, γ-) cover of X if: (1) Each x ∈ X is covered by infinitely many U ∈ U ; (2) Each finite F ⊆ X is co...

Motivated by the minimal tower problem, an earlier work studied diagonalizations of covers where the covers are related to linear quasiorders (τ -covers). We deal with two types of combinatorial questions which arise from this study. (1) Two new cardinals introduced in the topological study are expressed in terms of well known cardinals characteristics of the continuum. (2) We study the additiv...

We developed three types of covers that are easily fabricated from plastic screen locally manufactured in Thailand. The covers were designed to permit normal use of water jars for drinking, utility water uses, and water storage. Tests of the covers in the laboratory and field demonstrated that they could completely prevent successful development of Aedes aegypti (L.) in water jars. Initial expe...

Abstract: In pointfree topology, the point-finite covers introduced by Dowker and Strauss do not behave similarly to their classical counterparts with respect to transitive quasi-uniformities, contrarily to what happens with other familiar types of interior-preserving covers. The purpose of this paper is to remedy this by modifying the definition of Dowker and Strauss. We present arguments to j...

Hypophosphatasia is a rare hereditary disorder of bone metabolism.In this article, we presented the case of a male infant with a soft skull and short, deformed limbs at birth, followed by seizures and respiratory distress during admission in the neonatal intensive care unit (NICU). Prenatal ultrasound showed limb hypoplasia, skull hypomineralization, and polyhydramnios. Seizures occurred on day...