The information content of the autocorrelation function (ACF) of intensity fluctuations of the X–ray background (XRB) is analyzed. The tight upper limits set by ROSAT deep survey data on the ACF at arcmin scales imply strong constraints on clustering properties of X–ray sources at cosmological distances and on their contribution to the soft XRB. If quasars have a clustering radius r0 = 12–20 Mp...

Since the works of Newton and Lagrange, interpolation had been a mature technique in the numerical mathematics. Among the many interpolation methods, global or piecewise, the polynomial interpolation p(x) = a0 +a1x+ . . .+ anx expanded by the monomials is the simplest one, which is easy to handle mathematically. For higher accuracy, one always attempts to use a higher-order polynomial as an int...

Context The ability of ectothermic stream invertebrates to adapt the predicted increases in mean and extreme temperatures is crucial ensuring they continue exist.Aims To examine plasticity thermal limits Australian Paratya spp. (Decapoda, Atyidae) from streams eastern New South Wales (NSW). We hypothesised that upper lethal temperature (ULT, as indicated by median temperature, LT50) would be hi...

ABSTRACT Parental effects can prepare offspring for different environments and facilitate survival across generations. We exposed parental populations of the estuarine anemone, Nematostella vectensis, from Massachusetts to elevated temperatures quantified larval mortality a temperature gradient. found that exposure resulted in consistent increase thermal tolerance, as measured by at which 50% l...

One of the basic problems in discrete tomography is the reconstruction of discrete sets from few projections. Assuming that the set to be reconstructed fulfils some geometrical properties is a commonly used technique to reduce the number of possibly many different solutions of the same reconstruction problem. Since the reconstruction from two projections in the class of so-called hv-convex sets...

We investigate a class of multigroup dengue epidemic model. We show that the global dynamics are determined by the basic reproductive number R0. We present that when R0 ≤ 1, there is a unique disease-free equilibrium which is globally asymptotically stable; when R0 > 1, there exists a unique endemic equilibrium and it is globally asymptotically stable proved by a graph-theoretic approach to the...

In this paper, a periodic epidemic model is proposed in order to simulate the dynamics of pertussis transmission. We consider the waning of vaccine-induced immunity in the population. The basic reproduction number R0 is defined. It is shown that the disease-free equilibrium is globally asymptotically stable and the disease eventually disappears if R0 < 1, and there exists at least one positive ...

We consider the problem of estimating the basic reproduction number R0 from data on prevalence dynamics at the beginning of a disease outbreak. We derive discrete and continuous time models, some coefficients of which are to be fitted from data. We show that prevalence of the disease is sufficient to determine R0. We apply this method to chronic wasting disease spread in Alberta determining a r...