Routing Permutations on Graphs via Factors

We deal with the permutation routing problem on graphs modeling interconnection networks. In our model, calledrouting via factors, at each routing step, the communication pattern is a directed 1-factor in a symmetric digraph. This adds a new feature, that of continuous packet movement, to preciously studied routing types, where the routing of a permutation is reduced to a sequence of permutations from a given class. We especially focus on bipartite graphs and we give sufficient conditions for a graph to be rearrangeable in our model. We propose a general technic for routing via factors that we apply to the 2D mesh and the hypercube.     

Network structure and reaction mechanisms in high pressure and peroxide vulcanization of polybutadiene: Microstructural changes studied by 13C solid-state NMR

This article is concerned with the microstructural changes during peroxide and high pressure vulcanization of polybutadiene that is unfilled and filled with carbon black. The main tool is ¹³C solid-state NMR; it shows that vinyl unsaturations are consumed in both filled and unfilled samples under peroxide and high pressure vulcanization. Chemical shift calculations of unvulcanized polybutadiene show good agreement with the observed peaks. Calculations of proposed structures, based on a possible reaction mechanism, suggest that a large number of peaks will appear, each at very low intensity. Nevertheless, some changes can be seen as a result of the crosslinking reaction, and the results provide support for the suggested reaction mechanism. Thus, the proposed addition crosslinking mechanism over vinyl unsaturations seems to be a reasonable explanation of the crosslink formation in high pressure vulcanization. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2799–2806, 1999     

Techno-economic analysis of processes with integration of fluidized bed heat exchangers for H2 production – Part 2: Chemical-looping combustion

This work covers a techno-economic assessment for processes with inherent CO₂ separation, where a fluidized bed heat exchanger (FBHE) is used as heat source for steam reforming in a hydrogen production plant. This article builds upon the work presented in Part 1 of this study by Stenberg et al. [1], where a process excluding CO₂ capture was examined. Part 2 suggests two process configurations integrating steam reforming with a chemical-looping combustion (CLC) system, thus providing inherent CO₂ capture. The first system (case CM) uses natural gas as supplementary fuel whereas the second system (case CB) uses solid biomass, which enables net negative CO₂ emissions. In both systems, the reformer tubes are immersed in a bubbling fluidized bed where heat for steam reforming is efficiently transferred to the tubes. The processes include CO₂ compression for pipeline transportation, but excludes transport and storage. The CLC system is designed based on key parameters, such as the oxygen carrier circulation rate and oxygen transport capacity. The first system displays a process with net zero emissions and a hydrogen production efficiency which is estimated to 76.2%, which is almost 8% higher than the conventional process. The levelized production cost is 1.6% lower at below 2.6 €/kg H₂. The second system shows the possibility to reduce the emissions to ?34.1 g CO₂/MJ_H2 compared to the conventional plant which emits 80.7 g CO₂/MJ_H2. The hydrogen production efficiency is above 72% and around 2% higher than the conventional process. The capital investments are higher in this plant and the levelized hydrogen production cost is estimated to around 2.67 €/kg. The cost of CO₂ avoidance, based on a reference SMR plant with CO₂ capture, is low for both cases (?4.3 €/ton_CO2 for case CM and 2.7 €/ton_CO2 for case CB).     

Characterization of rubber-cellulose-fibre composites by mechanical measurements and electron microscopy

Mechanical measurements, SEM micrographs and crosslink density measurements on cellulose-fibre-filled natural rubber suggest that there are bonds between untreated cellulose fibres and the rubber matrix. Mechanical tests indicate that the dispersion or lack of dispersion of the fibres in the matrix is at least as influential a parameter in determining the strength of the composite as is the adhesion between fibre and matrix. Stress/strain measurements indicate that there is no obvious correlation between adhesion and the shape of the stress/strain curve unless the curve is clearly jagged.     

Multiple regulatory events influence human cytomegalovirus DNA polymerase (UL54) expression during viral infection

The human cytomegalovirus (HCMV) DNA polymerase gene (UL54; also called pol) is a prototypical early gene in that expression is mandatory for viral DNA replication. Recently, we have identified the major regulatory element in the UL54 promoter responsive to the major immediate early (MIE) proteins (UL122 and UL123) (J.A. Kerry, M.A. Priddy, and R. M. Stenberg, J. Virol. 68:4167-4176, 1994). Mutation of this element, inverted repeat sequence 1 (IR1), abrogates binding of cellular proteins to the UL54 promoter and reduces promoter activity in response to viral proteins in transient-transfection assays. To extend our studies on the UL54 promoter, we aimed to examine the role of IR1 in UL54 regulation throughout the course of infection. These studies show that viral proteins in addition to the MIE proteins can activate the UL54 promoter. Proteins from UL112-113 and IRS1/TRS1, recently identified as essential loci for transient complementation of HCMV oriLyt-dependent DNA replication, were found to function as transactivators of the UL54 promoter in association with MIE proteins. UL112-113 enhanced UL54 promoter activation by MIE proteins three- to fourfold. Constitutive expression of UL112-113 demonstrated that the MIE protein dependence of UL112-113 transactivational activity was not related to activation of cognate promoter sequences, suggesting that UL112-113 proteins function in cooperation with the MIE proteins. Mutation of IR1 was found to abrogate stimulation of the UL54 promoter by UL112-113, suggesting that this element is also involved in UL112-113 stimulatory activity. These results demonstrate that additional viral proteins influence UL54 promoter expression in transient-transfection assays via the IR1 element. To confirm the biological relevance of IR1 in regulating UL54 promoter activity during viral infection, a recombinant virus construct containing the UL54 promoter with a mutated IR1 element regulating expression of the chloramphenicol acetyltransferase (CAT) reporter gene (RVIRmCAT) was generated. Analysis of RVIRmCAT revealed that mutation of IR1 dramatically reduces UL54 promoter activity at early times after infection. However, at late times after infection CAT expression by RVIRmCAT, as assessed by RNA and protein levels, was approximately equivalent to expression by wild-type RVpolCAT. These data demonstrate IR1-independent regulation of the UL54 promoter at late times after infection. Together these results show that multiple regulatory events affect UL54 promoter expression during the course of infection.     

Ormond's disease

Three cases of Ormond's disease (syndrome) are described, and the aetiopathogenesis, clinical picture and diagnostics of the disease are dealt with in this report. Besides, the traditional therapy and the new therapeutic possibilities are discussed. For a disease of low incidence and assumed autoimmune origin malignancy cannot be excluded. Therefore, surgical exploration and histological verification are indispensable interventions in every case of Ormond's disease. In two of the present cases, steroid was administered in defence of percutaneous nephrostomy. In two cases, the recently recommended anti-oestrogen therapy was successful. Stagnation, or even regression, of the process followed. The authors are sure that they were the first in Hungary to administer anti-oestrogen to patients suffering from IFR.     

1998 update on antiphospholipid antibodies

T-lymphocyte recirculation appears to be slower in nude or irradiated rats as compared with normal rats. A mathematical model of T-lymphocyte recirculation that incorporates interactions between T cells and dendritic cells in the lymphoid tissue is presented. It is shown that these interactions are able to explain the differences in recirculation times between normal and nude or irradiated rats, and also the time-scales seen in long-term thoracic duct cannulations.     

Dither signals and quantization

The accuracy performance that an be achieved by post-processing the samples provided by a dithered quantizer is analysed in this paper for both stochastic and deterministic dithering. In the former case the quantization error average and variance are considered and the number of effective bits of the system output is evaluated for uniformly and Gaussian distributed dither signals. Then the accuracy achieved by using a deterministic dithering is analysed and a new approach for optimizing the system performance is proposed. All the reported results have been validated by means of computer simulations.     

Narrowband ISDN and broadband ISDN service and network interworking

For a significant period of time, B-ISDN will coexist with the 64-kb/s-based (narrowband) ISDN. The specification of a concept and the mapping functions employed for interworking between the two networks, in particular for voice services, is a major factor for the success of B-ISDN