In this study, we propose approximations to compute the steady-state performance measures of the M/GI/N + GI queue receiving Poisson arrivals with N identical servers, and general service and abandonment-time distributions. The approximations are based on scaling a single server M/GI/1 + GI queue for which we suggest a practical way to compute the waiting time distributions and their moments. T...

Around 2–4 in 1,000 people in Northern Europe have ulcerative colitis or Crohn’s disease (Rubin 2000). Both are chronic, relapsing, inflammatory disorders of the gastrointestinal tract with several shared clinical features, but with largely distinct risk factors, genetic, immunological, anatomical and histological features, and response to therapy (DTB 2003). Their treatment, which includes med...

Feature modeling is an important approach to dealing with variability at an abstract level in a hierarchical manner extensively used in software product lines. For its use in conjunction with other UML models and MDA approach, it is important to correctly integrate feature modeling into UML. In this paper, we present an approach to integrating feature modeling into UML that respects abstractnes...

We obtain a heavy-traffic limit for the GI/M/n+GI queue which includes the entire abandonment distribution. Our main approach is to scale the hazard rate function in an appropriate way such that our resulting diffusion approximation contains the entire hazard rate function. We then show through numerical studies that for various key performance measures, our approximations outperform those comm...

Four different fluid model formulations have been recently developed for Gt/GI/N+ GI queues, including a two-parameter fluid model in Whitt (2006) by tracking elapsed service and patience times of each customer, a measure-valued fluid model in Kang and Ramanan (2010) and its extension in Zuñiga (2014) by tracking elapsed service and patience times of each customer, and a measure-valued fluid mo...

Around 2–4 in 1,000 people in Northern Europe have ulcerative colitis or Crohn’s disease (Rubin 2000). Both are chronic, relapsing, inflammatory disorders of the gastrointestinal tract with several shared clinical features, but with largely distinct risk factors, genetic, immunological, anatomical and histological features, and response to therapy (DTB 2003). Their treatment, which includes med...

Next generation middleware must support applications in the face of increasing diversity in interaction paradigms, end system types and network styles. Therefore, to secure applications, security policies must be configured and indeed reconfigured at runtime. In this paper, we propose an approach combining the openness of reflective middleware with the flexibility of programmable security to me...

Motivated by applications to service systems, we develop simple engineering approximation formulas for the steady-state performance of heavily-loaded G/GI/n+GI multi-server queues, which can have non-Poisson and non-renewal arrivals and non-exponential service-time and patience-time distributions. The formulas are based on recently established Gaussian manyserver heavy-traffic limits, but invol...

Although gastrointestinal involvement by metastatic malignant melanoma is common but primary gastrointestinal (GI) melanoma has been reported in rare cases. In this study we report two cases of primary gastrointestinal malignant melanoma that one of them is a known case of neurofibromatosis type 1(NF1). Both cases showed no evidence of any lesions in skin and eye. Malignant melanoma of GI tract...

Proposition. Let G be a group and (Gi, i ∈ I) a family of subgroups of G. If (i) for each i, j ∈ I there exists k ∈ I with 〈Gi, Gj〉 ≤ Gk, and (ii) Gi is simple for all i ∈ I, then H = ⋃ i∈I Gi is a simple subgroup of G. Proof. Choose i, j ∈ I. Observe that (ii) implies Gi, Gj 6= ∅ because the definition of a simple group excludes this possibility. Clearly, Gi is a group and a subset of 〈Gi, Gj〉...