A note on the prediction of liquid hold-up with the stratified roll wave regime for gas/liquidco-current flow in horizontal pipes.

This note presents a simple model for prediction of liquid hold-up in two-phase horizontal pipe flow for the stratified roll wave (St+RW) flow regime. Liquid hold-up data for horizontal two-phase pipe flow [1, 2, 3, 4, 5 and 6] exhibit a steady increase with liquid velocity and a more dramatic fall with increasing gas rate as shown by Hand et al. [7 and 8] for example. In addition the liquid hold-up is reported to show an additional variation with pipe diameter. Generally, if the initial liquid rate for the no-gas flow condition gives a liquid height below the pipe centre line, the flow patterns pass successively through the stratified (St), stratified ripple (St+R), stratified roll wave, film plus droplet (F+D) and finally the annular (A+D, A+RW, A+BTS) regimes as the gas rate is increased. Hand et al. [7 and 8] have given a detailed description of this progression in flow regime development and definitions of the patterns involved. Despite the fact that there are over one hundred models which have been developed to predict liquid hold-up, none have been shown to be universally useful, while only a handful have proven to be applicable to specific flow regimes [9, 10, 11 and 12]. One of the most intractable regimes to predict has been the stratified roll wave pattern where the liquid hold-up shows the most dramatic change with gas flow rate. It has been suggested that the momentum balance-type models, which give both hold-up and pressure drop prediction, can predict universally for all flow regimes but particularly in the case of the difficult stratified roll wave pattern. Donnelly [1] recently demonstrated that the momentum balance models experienced some difficulties in the prediction of this regime. Without going into lengthy details, these models differ in the assumed friction factor or shear stress on the surfaces within the pipe particularly at the liquid–gas interface. The Baker–Jardine model [13] when tested against the 0.0454 m i.d. data of Nguyen [2] exhibited a wide scatter for both liquid hold-up and pressure drop as shown in Fig. 1. The Andritsos–Hanratty model [14] gave better prediction of pressure drop but a wide scatter for liquid hold-up estimation (cf. Fig. 2) when tested against the 0.0935 m i.d. data of Hand [5]. The Spedding–Hand model [15], shown in Fig. 3 against the data of Hand [5], gave improved performance but was still unsatisfactory with the prediction of hold-up for stratified-type flows. The MARS model of Grolman [6] gave better prediction of hold-up (cf. Fig. 4) but deterioration in the estimation of pressure drop when tested against the data of Nguyen [2]. Thus no method is available that will accurately predict liquid hold-up across the whole range of flow patterns but particularly for the stratified plus roll wavy regime. The position is particularly unfortunate since the stratified-type regimes are perhaps the most predominant pattern found in multiphase lines.

Attitudes to community relations in Northern Ireland: signs of optimisim in the post-cease fire period?

This article uses attitudinal data to explore Catholic and Protestant perspectives on community relations and equality since the paramilitary cease fires in 1994. Although attitudes tend to fluctuate with the‘headline grabbing'events of the day, the article argues that there are signs that some fundamental changes have taken place in the post cease fire period. Of particular importance in this regard is the positive response recorded by the Catholic community towards government measures to tackle disadvantage and inequality. Equally significant is the protestant response to many of these measures which is often one of ambivalence rather than derision. In so far as the data appear to challenge the‘zero-sum'game that traditionally underpins relations between the two communities in Northern Ireland, they provide some grounds for optimism. Yet such optimism is tempered somewhat by the seeds of discontent which are manifest within the protestant community, particularly around issues of equality in employment and cultural traditions. Despite the more positive assessment of community relations and equality in 2002, it is argued that further monitoring will be required to determine the long-term effects of policy reform on relationships between the two communit

Perspectives for quantum state engineering via high nonlinearity in a double-EIT regime

We analyse the possibilities for quantum state engineering offered by a model for Kerr-type nonlinearity enhanced by electromagnetically induced transparency (EIT), which was recently proposed by Petrosyan and Kurizki [2002, Phys. Rev. A, 65, 33833]. We go beyond the semiclassical treatment and derive a quantum version of the model with both a full Hamiltonian approach and an analysis in terms of dressed states. The preparation of an entangled coherent state via a cross-phase modulation effect is demonstrated. We briefly show that the violation of locality for such an entangled coherent state is robust against low detection efficiency. Finally, we investigate the possibility of a bi-chromatic photon blockade realized via the interaction of a low density beam of atoms with a bi-modal electromagnetic cavity which is externally driven. We show the effectiveness of the blockade effect even when more than a single atom is inside the cavity. The possibility to control two different cavity modes allows some insights into the generation of an entangled state of cavity modes.

Bradykinins and their precursor Cdnas from the skin of the Fire-Bellied Toad (Bombina orientalis)

Bradykinin and (Thr6)-bradykinin have been identified in the defensive skin secretion of the fire-bellied toad, Bombina orientalis. The homologous cDNAs for both peptides were cloned from a skin library using a 3'- and 5'-RACE strategy. Kininogen-1 (BOK-1) contained an open-reading frame of 167 amino acid residues encoding four repeats of bradykinin, and kininogen-2 (BOK-2) contained an open-reading frame of 161 amino acid residues encoding two repeats of (Thr6)-bradykinin. Alignment of both precursor nucleotide and amino acid sequences revealed a high degree of structural similarity. These amphibian skin kininogens/preprobradykinins are not biologically analogous to mammalian kininogens.