Pulse vaccination is an effective and important strategy for the elimination of infectious diseases. A delayed SEIRS epidemic model with pulse vaccination and varying total population size is proposed in this paper. We point out, if R* < 1, the infectious population disappear so the disease dies out, while if R(*) > 1, the infectious population persist. Our results indicate that a long period o...

BACKGROUND The objective of this study is to produce a detailed yet robust description of the epidemiologic transition in The Netherlands. METHODS National mortality data on sex, age, cause of death and calendar year (1875-1992) were extracted from official publications. For the entire period, 27 causes of death could be distinguished, while 65 causes (nested within the 27) could be studied f...

PURPOSE To analize changing trends in indications and surgical techniques of corneal transplantation at an ophthalmological tertiary referral center in Colombia over a 7 year period. METHODS A retrospective analysis was performed of medical records from patients who underwent corneal transplantation surgeries at Fundación Oftalmológica de Santander (FOSCAL) in Bucaramanga, Colombia, between A...

To get some intuition, we begin with the group of real numbers R under addition. A trivial upper bound for the size of a sum set is |A + A| ≤ |A| 2+|A| 2 (equality is obtained when every pair of elements of A have a distinct sum). If we build A by taking elements of R at random, then we expect |A+A| to be very close to this upper bound, since the probability of a1+a2 = a3+a4 is very small (wher...

The Clifford tori in S constitue a one-parameter family of flat, two-dimensional, constant mean curvature (CMC) submanifolds. This paper demonstrates that new, topologically non-trivial CMC surfaces resembling a pair of neighbouring Clifford tori connected at a sub-lattice consisting of at least two points by small catenoidal bridges can be constructed by perturbative PDE methods. That is, one ...

The retro-cue effect (RCE) describes superior working memory performance for validly cued stimulus locations long after encoding has ended. Importantly, this happens with delays beyond the range of iconic memory. In general, the RCE is a stable phenomenon that emerges under varied stimulus configurations and timing parameters. We investigated its susceptibility to dual-task interference to dete...

We derive a new representation of Lagrangian subspaces in the form ImΠT [ I X ] , where Π is a symplectic matrix which is the product of a permutation matrix and a real orthogonal diagonal matrix, and X satisfies |Xij | ≤ { 1 if i = j, √ 2 if i = j. This representation allows us to limit element growth in the context of doubling algorithms for the computation of Lagrangian subspaces and the sol...

By reparametrization, one may assume that γ is Lipschitz with constant equal to length(γ). We will also make use of the following simple (and well-known) criterion: a compact set Γ is the image of a rectifiable curve if and only if it is connected and H(Γ) < ∞. Indeed, one may choose γ so that length(γ) ≤ CH(Γ); see, for example, [1, 2]. Here and below, H denotes the one-dimensional Hausdorff m...