A call admission control scheme for ATM networks using a simplequality estimate

The authors propose a call admission control scheme based on a method of estimating cell loss quality for individual bursty traffic sources. The estimate is expressed in terms of virtual cell loss probability, which may be defined by two traffic characteristic parameters alone: peak and mean rate. The approach is suitable for the estimation of real cell loss probability in heterogeneous and homogeneous traffic models when burst length is larger than buffer capacity. The concept of virtual cell loss probability is extended to the individual call level so as to be able to estimate the quality of service (QOS) provided to individual calls. A virtual bandwidth method is used to develop a practical call admission control system. Quality is ensured by combining a traffic clustering scheme, with a scheme for assigning individual clusters to subcapacities of a link. Priority levels are presented in terms of the class of QOS required, i.e., deterministic or statistical, and the allocation of virtual bandwidth is discussed in terms of both QOS class and traffic characteristics     

In vitro interleukin 12 activation of peripheral blood CD3(+)CD56(+) and CD3(+)CD56(-) gammadelta T cells from glioblastoma patients

Interleukin (IL)-12 has recently been shown to be directly involved in the activation of natural killer and alphabeta T cells via an IL-2-independent pathway. We show here that another type of human cytotoxic cell, gammadelta T cells activated by solid-phase anti-CD3 antibody and expanded using IL-2, obtained, in this case, from the peripheral blood of glioblastoma patients, displays significant tumoricidal activity. In addition, its cytotoxic activity against K562 or Daudi cells or against autologous glioblastoma targets (but not lymphocytes) is significantly enhanced when costimulated with IL-2 and IL-12. To study this synergistic activation by the two interleukins of the patients' gammadelta T cells, we screened the cells for the presence of the IL-2 receptor (IL-2R) and IL-12 receptor (IL-12R) using both flow cytometric analysis and PCR. The patients' gammadelta T cells constitutively expressed the high-affinity IL-2R; when stimulated with IL-12 plus IL-2, the levels of IL-2Ralpha and IL-2Rbeta increased, whereas that of IL-2gamma did not. They also expressed marginal levels of low-affinity IL-12R both immediately after IL-2 expansion and after 24-h incubation, and significantly higher levels after 72-h incubation, consistent with the level of gammadelta T-cell activation. IL-12 alone induced little proliferation of patients' gammadelta T cells in a 24-h assay and none in a 72-h assay; however, it caused a marked inhibition of the IL-2-induced proliferative response in the 72-h assay. The synergistic action of IL-2 and IL-12 was completely abolished by combined pretreatment with anti-IL-2alpha, beta, and gamma mAbs. IL-12-mediated enhancement of gammadelta T cell cytotoxic activity was inhibited by anti-IL-2Rbeta mAb in a dose-dependent manner but not by anti-IL-2Ralpha or anti-IL-2Rgamma mAbs. Thus, the increased expression of the IL-2Rbeta is critical for the synergistic activation of gammadelta T cells by IL-12 plus IL-2; it is also probable that at least the low-affinity IL-12R contributes to the activation of gammadelta T cells mediated by either IL-12 alone or IL-12 plus IL-2. We have, therefore, demonstrated that IL-12 can stimulate the cytotoxic activity of gammadelta T cells from glioblastoma patients, acting via the IL-2Rbeta component of the IL-2R and low-affinity IL-12R. IL-12 activation of patients' gammadelta T cells could possibly be of potential use in the treatment of glioblastoma patients.     

Mechanical properties of the Ni3(Si,Ti) alloys doped with carbon and beryllium

The Ni₃(Si, Ti) alloys doped with small amounts of carbon and beryllium were tensile tested in two environments, vacuum and air, over a wide range of test temperatures. The yield stresses of the carbon-doped alloys were almost identical to the undoped alloys while those of the beryllium-doped alloys were slightly higher than the undoped Ni₃(Si, Ti) alloys. The doping with carbon enhanced the elongation and ultimate tensile strength (UTS) whereas doping with beryllium reduced the elongation over the entire temperature range tested. The fracture patterns were primarily associated with the ductility behaviour. As the elongation (or UTS) increased, the fracture pattern changed from the intergranular to the transgranular fracture patterns. No environmental embrittlement of the ductility of the carbon-doped alloys was found at ambient temperatures but it was evident at elevated temperatures. Ductilities were reduced at high temperatures when the carbon-doped alloys were tensile tested in air. At high temperatures the environmental embrittlement observed is suggested to be due to the penetration of (free) oxygen into the grain boundaries causing the ductility loss in the carbondoped alloys.     

Synchrobetatron resonance driven by deflecting modes of RF cavities

Synchrobetatron resonance driven by deflecting modes of rf cavities, which was first studied by Sundelin, is extensively reinvestigated. Both the multi-turn effect and the single-passage effect are studied carefully and some extension on the work of Sundelin is achieved. The present theory is applied to the TRISTAN electron-positron storage ring as a numerical example.     

Thermodynamical,economical and environmental evaluation of high efficiency gas turbine cogeneration systems

The paper evaluates the thermodynamical, economical and environmental characteristics of a cogeneration system composed of a gas turbine and a waste heat boiler (system A). Two other systems for increasing power generating efficiency are also evaluated, namely systems B and C, which are constructed by incorporating a regenerative cycle and a dual fluid cycle, respectively, into system A. It has been estimated that system C satisfies an environmental constraint that the nitrogen oxide density exhausted should be less than 100 parts in 10⁶, and that systems A and B also satisfy this constraint if a small amount of steam is injected into the combustor. The power generating efficiencies of systems A and B, in this case, and that of system C have been estimated to be 33.5%, 38.5% and 41.2%, respectively; i.e. the efficiencies of systems B and C can be improved noticeably compared with that of system A. The economics of these systems have also been evaluated based on the value of a profit index, and the systems are all estimated to be economically viable under the conditions assumed. As a result, it has been shown that it is possible to construct cogeneration systems with satisfactory characteristics of both environmental protection and profitability if system A is used in districts where the heat demand is large, system C in districts where the heat demand is small, and system B in districts with intermediate heat demand.     

Surface activity of the lipid products hydrolyzed with lipase and phospholipase A-2

We examined thein vitro surface activity, immersional wettability and adhesional wettability shown by aqueous solutions of soy lysophospholipid (SLP)/monoglyceride (MG)/fatty acid (FA), SLP/FA and SLP/MG, and found that many lipid mixtures showed significant surface activity when their MG and FA components consisted of polyunsaturated FA and/or medium chain FA. The more unsaturated the FA, the higher the surface activity. A mixture of SLP/medium chain fatty acid MG (medium chain MG)/medium chain FA showed the highest surface activity, and was comparable to an Aerosol-OT surfactant, the most effective wetting agent. SLP/polyunsaturated FA monoglyceride (polyunsaturated MG)/polyunsaturated FA, SLP/medium chain FA, and SLP/polyunsaturated FA, SLP/medium chain MG, and SLP/polyunsaturated MG also showed a high degree of activity. Wettability decreased rapidly when the amount of saturated, long chain FA moieties increased. It is recognized that the degrees of unsaturation and the chain length of FAs in the lipid mixtures have a decisive influence on surface activities. Higher ratios of MG and FA to SLP gave higher activity; and solubilizers such as bile salts were necessary to dissolve them in water.     

Defect structure and electrical conductivity in rapidly-quenched and slowly-cooled rhombohedral solid solutions of the system Bi2O3-BaO

The solid solubility limit, grain orientation, defect structure and electrical conductivity of solidified rhombohedral specimens in the Bi₂O₃-BaO system are described. The c-axes (in hexagonal notation) of solidified specimens were almost entirely oriented along the platelet/film thickness. Slow-cooling (∼ 10⁻²° Csec⁻¹) of the system gave solid solutions with substitutional type of 2BaO → 2Ba_Bi′ + 20+ V ₀ ^.. for 12 to 32 mol % BaO. High-temperature modification of slowly-cooled sample (16 mol % BaO) showed a conductivity of 8.8×10⁻¹ Ω⁻¹ cm ⁻¹ at 600° C along the conduction plane (perpendicular to the c-axis). Rapid quenching (∼ 10⁵° C sec⁻¹) produced solid solutions for 8 to 20 mol % BaO introducing interstitial Ba²⁺ (10–12 mol % BaO) and Schottky type defects such as V_Bi‴ and V _Bi ^‴ and V ₀ ^.. (16 to 20 mol % BaO), however the high-temperature modification of the rhombohedral structure could not be frozen.     

Pharmacokinetics of pentazocine and its occupancy of opioid receptors in rat brain

In order to assess quantitatively the pharmacodynamic process of pentazocine (PTZ), time courses of its plasma concentration and of the occupation of specific opioid receptors in the brain were investigated after intravenous (i.v.) administration of PTZ to rats. The plasma concentration of PTZ was determined by HPLC and the pharmacokinetic parameters were analyzed using nonlinear least-squares analysis. Measurement of ex vivo receptor occupation was made by comparing the specific [3H]naloxone (opioid receptor antagonist) binding in vitro to the crude P2-synaptosomal fractions between vehicle-treated rats (control) and PTZ-treated rats. Following the i.v. administration of PTZ, the occupancy of specific opioid receptors decreased rapidly until 10 min, depending on the two pharmacological doses (2.5 and 10 mg/kg). The results strongly suggest the fast binding kinetics of PTZ in terms of its association with and dissociation from specific opioid receptor sites in the brain in addition to its fast rate of disappearance from the brain compartment. Furthermore, we demonstrated that the time profile of receptor occupancy correlated well (r = 0.8650) with that of the unbound concentration in plasma until 120 min after the i.v. administration of PTZ to rats.