Flow control in message-switched communications networks

A queueing network model is used to analyse the performance of flow-control techniques. Analytical expressions for throughput and mean end-to-end delay are derived. Numerical results show that, under isarithmic control, the total network throughput is degraded significantly when the demand from one user is increased. Throughput degradation can be avoided if an end-to-end or a two-level control is used. Of these two schemes, the two-level control gives a higher throughput to the user with increased demand. This often results in a higher total throughput. The mean end-to-end delay of the various flow-control techniques is also characterized.     

Liquefaction of aspen poplar wood

Dried and green aspen poplar wood suspended in water containing alkaline catalysts has been converted completely to an oil, water-soluble chemicals and gases if heated for one hour in the presence of carbon monoxide in a rocking batch reactor. Within the ranges of parameters studied: temperature (593—633 K), nominal reaction times (0—1 h), water-to-wood ratio (0.5:1—5:1), catalyst (Na₂CO₃, K₂CO₃, NaOH), amount of catalyst (7.0—12.5 wt %) and initial hydrogen to carbon monoxide ratios (2:1—0:1), the water-to-wood ratio was most important. Oil yields of ?50% with a carbon plus hydrogen content of ?80% and representing a carbon recovery of ?66% were obtained. The higher heats of combustion ranged from 32.2 to 36.0 MJ/kg.     

A reappraisal of the stereoselective metabolism of nicotine to nicotine-1'-N-oxide

1. The cis and trans 1'-N-oxide metabolites of (2'R)-(+)-nicotine have the absolute configuration (1'S; 2'R) and (1'R; 2'R), respectively, and not the reverse as previously published. 2. Reinterpretation of metabolic data in the light of this reassignment reveals that N-oxidation of nicotine leads preferentially to the (1'R)-N-oxide, with little dependence on the configuration of the 2'-centre. 3. It is proposed that (2'S)-(-)-nicotine and (2'R)-(+)-nicotine bind to the same enzymic site by two distinct modes of binding; each of these modes involves the more basic centre (in this case the pyrrolidine ring) as the governing binding moiety.     

Granulocytic sarcoma (chloroma) initially seen as acute mastoiditis

Granulocytic sarcoma (chloroma) is a localized tumefaction of immature granulocytes that is typically seen in association with myelogenous leukemia. The primitive cell population seen in biopsy material may be misinterpreted as histiocytic lymphoma or other sarcoma unless additional studies are performed. We saw a 36-year-old woman with promyelocytic leukemia in remission who had the signs and symptoms of an acute coalescent mastoiditis. Histologic examination of the surgical specimen, however, demonstrated a granulocytic sarcoma. Our case exemplifies some of the difficulties that may be encountered in the diagnosis of granulocytic sarcoma and illustrates the point that symptoms of an inflammatory process in a patient with a diagnosis of leukemia must be regarded with a degree of suspicion.