The task is to improve the shadow function. For that purpose the Earth is regarded as a sphere and the shadows as two cones. The former is taken for the umbra and the latter for the penumbra. After that the influence of the Earth´s atmosphere was taken into account: the astronomic refraction and the atmospheric absorption. The final form of the shadow function gives Eq. (17). The theory is brought to completion by numerical applications.
Adenine-induced model of chronic kidney disease (CKD) is a widely used model especially in studies testing novel nephroprotective agents. We investigated the effects of adenineinduced CKD in rats on the activities of some xenobiotic metabolizing enzymes in liver and kidneys, and on some in vivo indicators of drug metabolism (viz pentobarbitone sleeping time, and plasma concentration of theophylline 90 min post administration). CKD was induced by orally feeding adenine (0.25 % w/w) for 35 days. Adenine induced all the characteristics of CKD, which was confirmed by biochemical and histological findings. Glutathione concentration and activities of some enzymes involved in its metabolism were reduced in kidneys and livers of rats with CKD. Renal CYP450 1A1 activity was significantly inhibited by adenine, but other measured isoenzymes (1A2, 3A4 and 2E1) were not significantly affected. Adenine significantly prolonged pentobarbitone-sleeping time and increased plasma theophylline concentration 90 min post administration. Adenine also induced a moderate degree of hepatic damages as indicated histologically and by significant elevations in some plasma enzymes. The results suggest that adenine-induced CKD is associated with significant in vivo inhibitory activities on some drug-metabolizing enzymes, with most of the effect on the kidneys rather than the liver., M. Al Za’abi, A. Shalaby, P. Manoj, B. H. Ali., and Obsahuje bibliografii
We present preliminary results from a spectroscopic survey for absorption line profile variations among the O stars. Our data consist of more than 1000 high quality spectra of 46 bright O stars which were obtained with sufficient time resolution to sample variations with timescales of hours to days. Most spectral types and luminosity classes are represented. We find that about 31% of these stars exhibit photospheric variability which probably arises from organized velocity fields. The remaining stars are either constant (31% of the sample) or possess variability associated with their winds (43% of the sample, including 2 of the photospheric variables). We present examples illustrating each of these classes of behaviour, and discuss preliminary implications and future
directions of this work.
For an ordered set W = {w1, w2, . . . , wk} of vertices in a connected graph G and a vertex v of G, the code of v with respect to W is the k-vector cW (v) = (d(v, w1), d(v, w2), . . . , d(v, wk)). The set W is an independent resolving set for G if (1) W is independent in G and (2) distinct vertices have distinct codes with respect to W. The cardinality of a minimum independent resolving set in G is the independent resolving number ir(G). We study the existence of independent resolving sets in graphs, characterize all nontrivial connected graphs G of order n with ir(G) = 1, n − 1, n − 2, and present several realization results. It is shown that for every pair r, k of integers with k ≥ 2 and 0 ≤ r ≤ k, there exists a connected graph G with ir(G) = k such that exactly r vertices belong to every minimum independent resolving set of G.
We show that the index defined via a trace for Fredholm elements in a Banach algebra has the property that an index zero Fredholm element can be decomposed as the sum of an invertible element and an element in the socle. We identify the set of index zero Fredholm elements as an upper semiregularity with the Jacobson property. The Weyl spectrum is then characterized in terms of the index., Jacobus J. Grobler, Heinrich Raubenheimer, Andre Swartz., and Obsahuje seznam literatury
By a ternary structure we mean an ordered pair (X0, T0), where X0 is a finite nonempty set and T0 is a ternary relation on X0. By the underlying graph of a ternary structure (X0, T0) we mean the (undirected) graph G with the properties that X0 is its vertex set and distinct vertices u and v of G are adjacent if and only if {x ∈ X0 ; T0(u, x, v)}∪{x ∈ X0 ; T0(v,x,u)} = {u, v}. A ternary structure (X0, T0) is said to be the B-structure of a connected graph G if X0 is the vertex set of G and the following statement holds for all u, x,y ∈ X0: T0(x, u, y) if and only if u belongs to an induced x − y path in G. It is clear that if a ternary structure (X0, T0) is the B-structure of a connected graph G, then G is the underlying graph of (X0, T0). We will prove that there exists no sentence σ of the first-order logic such that a ternary structure (X0, T0) with a connected underlying graph G is the B-structure of G if and only if (X0, T0) satisfies σ.
The inertia set of a symmetric sign pattern $A$ is the set $i(A)=\lbrace i(B) \mid B=B^T \in Q(A)\rbrace $, where $i(B)$ denotes the inertia of real symmetric matrix $B$, and $Q(A)$ denotes the sign pattern class of $A$. In this paper, a complete characterization on the inertia set of the nonnegative symmetric sign pattern $A$ in which each diagonal entry is zero and all off-diagonal entries are positive is obtained. Further, we also consider the bound for the numbers of nonzero entries in the nonnegative symmetric sign patterns $A$ with zero diagonal that require unique inertia.