Sequential Allocation Method Research Articles

The Effect-Site Concentration of Remifentanil Blunting Cardiovascular Responses to Tracheal Intubation and Skin Incision During Bispectral Index-Guided Propofol Anesthesia

We sought to determine the effect-site concentration of remifentanil blunting sympathetic responses to tracheal intubation and skin incision during bispectral index (BIS)-guided propofol anesthesia. Forty-one ASA physical status I-II patients, aged 20-65 yr and undergoing major abdominal surgery, were randomly assigned to one of two groups: tracheal intubation (group TI, n = 20) or skin incision (group SI, n = 21). All patients received a target-controlled infusion of propofol of 4 microg/mL, which was then adjusted to maintain a BIS value ranging between 40 and 50. The effect-site concentration of remifentanil blocking the sympathetic responses to tracheal intubation and skin incision in 50% of cases (Ce50) was determined using an up-and-down sequential allocation method. The mean (95% confidence interval [CI]) Ce50 of remifentanil was 5.0 ng/mL for TI (95% CI, 4.7-5.4 ng/mL) and 2.1 ng/mL for SI (95% CI, 1.4-2.8 ng/mL). This study shows that effect-site concentrations of remifentanil of 5 ng/mL and 2 ng/mL are effective in blunting sympathetic responses to tracheal intubation and skin incision in 50% of patients when combined with a BIS-guided target controlled infusion of propofol.

An efficient memory allocation scheme for Huffman coding of multiple sources

In this paper, we propose an efficient memory allocation scheme for memory-constrained Huffman coding of multiple sources, which can be applied to many adaptive variable-length coding systems. The allocation of a given memory is performed in two stages. At the first stage, the iterative bisection algorithm based on the Lagrange optimization method is used to find a Lagrange allocation , which is either optimal or close to the optimal allocation. In the latter case, the Lagrange method does not fully allocate the given memory and a sequential allocation method is introduced as the second stage to allocate the remaining memory, which is performed in a greedy manner. To explain the proposed allocation scheme, we introduce a function, b ̂ (l) , which approximates the relation between the average bitrate b and the Huffman table size l , and discuss its properties. The use of this function considerably reduces the computational burden for memory allocation. We apply the proposed memory allocation scheme to memory-constrained conditional entropy coding of vector quantization indices for image compression. Simulations show that the proposed memory allocation scheme provides almost optimal performance, which is far better than can be achieved with conventional simple allocation methods.

Optimal Search Model with Compulsory Stop for a Randomly Arriving Target

Abstract One target appears in one of regions at a random time and will thereafter remain there. The searcher has the available total search time T. Exponential-type detection functions are assumed. The search is terminated compulsorily at a certain random time. The problem is to maximize a probability of detecting the target. Necessary and sufficient conditions for an optimal policy are derived and a sequential allocation method of search time is proposed. The case of one region is solved explicitly and an example of this case is given.