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We consider a multiserver queueing system in which customers request service from a random number of identical servers. In contrast to batch arrival queues, customers cannot begin service until all required servers are available. Servers assigned to the same customer may free separately. For this model, we derive the steady-state distribution for waiting(More)
PASTA (Poisson Arrivals See Time Averages) is a term coined by R. Wolff in his well known 1982 paper. In keeping with Wolff's terminology, we use the term anti-PASTA to refer to the following converse of PASTA. Given that arrivals do indeed see time averages, when must the arrival process necessarily be Poisson? We show that anti-PASTA is satisfied in a(More)
BACKGROUND Chronic obstructive pulmonary disease and emphysema are a frequent result of long-term smoking, but the exact mechanisms, specifically which types of cells are associated with the lung destruction, are unclear. METHODS AND FINDINGS We studied different subsets of lymphocytes taken from portions of human lungs removed surgically to find out(More)
We empirically explore the, accuracy of an easily computed approximation for long run, average performance measures such as expected delay and probability of delay in multiserver queueing systems with exponential service times and periodic (sinusoidal) Poisson arrival processes. The pointwise stationary approximation is computed by integrating over time(More)
Many organizations, such as banks, airlines, telecommunications companies, and police departments, routinely use queueing models to help determine capacity levels needed to respond to experienced demands in a timely fashion. Though queueing analysis has been used in hospitals and other healthcare settings, its use in this sector is not widespread. Yet,(More)
We examine the relative effects of several service order disciplines on important operating characteristics of queues in which customers request a random number of servers. This class of queues is characterized by customers who cannot begin service until all required servers are available. We show that for many systems in this class, it is possible to(More)
We consider a queueing system with two types of servers and two types of customers. General-use servers can provide service to either customer type while limited-use servers can be used only for one of the two. Though the apparent Markovian state space of this system is five-dimensional, we show that an aggregation results in an exact two-dimensional(More)
RATIONALE Data about the influence of the type of sedation on yield, complications, and tolerance of endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) are based mostly on retrospective studies and are largely inconsistent. OBJECTIVES To determine whether the type of sedation influences the diagnostic yield of EBUS-TBNA, its(More)
BACKGROUND This study implemented and evaluated a point-of-care, wireless Internet access using smart phones for information retrieval during daily clinical rounds and academic activities of internal medicine residents in a community hospital. We did the project to assess the feasibility of using smart phones as an alternative to reach online medical(More)