A Comment on Self-Tuning and Vanishing Cosmological Constant in the Brane World

In this note we elaborate on various five dimensional contributions to the effective 4D cosmological constant in brane systems. In solutions with vanishing 5D cosmological constant we describe a non-local mechanism of cancellation of vacuum energy between the brane and the singularities. We comment on a hidden fine tuning which is implied by this observation.Comment: 7 pages, Latex, final version to appear in Phys. Lett.

Utilisation of coal fly ash in the manufacture of useful materials

Fly ash, if not utilised, is considered a waste product. Zeolitisation of coal fly ash offers the opportunity to create an added value product from a waste stream. Optimisation of the two-step zeolitisation process is necessary in order to render the process profitable. The Objective of this thesis is to analyse the optimisation of Si extraction from fly ash and the conditions of crystallisation. The type of synthetic zeolites produced were found to be highly dependent on the conditions of the crystallisation process, which has produced zeolite Na-P1, sodalite, zeolite Na-A, zeolite K-A and other species. Crystallisation parameters explored by this thesis include pH, sodium aluminate addition, time at which ash and leachate are separated, length of crystallisation period, temperature, and control experiments on Si leaching from glassware. Further experimentation analysed the effects of a closed loop system on yield, variations in ash used in the leaching process, generation of floating zeolite via precipitation on cenospheres, highly caustic ash leaching, and Ga and Ge content analysis of ash leachate. Eight sets of cation exchange capacity tests were carried out using synthetic acid mine drainage and various zeolites, zeolitised ash, and untreated ash

Utilisation of fly ash in the manufacture of zeolites

Disposal of CFA is a problem of increasing concern, due to the environmental impact of CFA. Beneficiation processes such as the RockTron process are capable of producing various value-added products, and the Delta product is apt for use in the synthesis of zeolites. The current study explores hydrothermal Si extraction, fusion assisted extraction and a novel microwave fusion process with a performance comparable to the fusion process. The extraction process was optimised for the Delta ash, and compared to other ashes and rice husk ash. In the optimisation of the crystallisation process, the influence of sodium aluminate addition on the properties of zeolites was examined. The effects of alkalinity, sodium source and salt concentration were investigated using XRD, SEM, AAS, CEC and PSD. A concurrent decrease in Si and Al in the crystallisation solution was observed as amorphous material was consumed. This crystal growth phase occurs earlier with higher concentrations of sodium aluminate and NaCl. Addition of NaCl can improve crystallinity, yield and CEC and decrease particle size. Optimised results demonstrated good repeatability. The best estimated yield was 264 g/kg FA, with a CEC of 4.8 meq/g. Buoyant zeolites were synthesised through seeding of the crystallisation process with cenospheres. The products consisted of 77% cenospheres and 23% zeolite

Creativity out of chaos

Creativity is said to be highly desired in post-modern and post-industrial organizations Creativity and anarchy on the one hand, and managerialism, on the other, can be seen as different forms of knowledge, two opposed ideals. In many organizational as well as societal reforms we currently observe it is the managerialist ideal that wins over the anarchic. In this paper, we wonder if people fear anarchy? We reflect on the possible reasons for the fear, and we also try to explain why we believe that anarchic organizing should not be avoided or feared

Synthesis, antiprotozoal and antibacterial activity of nitro- and halogeno-substituted benzimidazole derivatives

Two series of benzimidazole derivatives were sythesised. The first one was based on 5,6-dinitrobenzimidazole, the second one comprises 2-thioalkyl- and thioaryl-substituted modified benzimidazoles. Antibacterial and antiprotozoal. activity of the newly obtained compounds was studied. Some thioalkyl derivatives showed remarkable activity against nosocomial strains of Stenotrophomonas malthophilia, and an activity comparable to that of metronidazole against Gram-positive and Gram-negative bacteria. Of the tested compounds, 5,6-dichloro-2-(4-nitrobenzylthio)-benzimidazole showed the most distinct antiprotozoal activity

The human TRPA1 intrinsic cold and heat sensitivity involves separate channel structures beyond the N-ARD domain

TRP channels sense temperatures ranging from noxious cold to noxious heat. Whether specialized TRP thermosensor modules exist and how they control channel pore gating is unknown. We studied purified human TRPA1 (hTRPA1) truncated proteins to gain insight into the temperature gating of hTRPA1. In patch-clamp bilayer recordings, ∆1–688 hTRPA1, without the N-terminal ankyrin repeat domain (N-ARD), was more sensitive to cold and heat, whereas ∆1–854 hTRPA1, also lacking the S1–S4 voltage sensing-like domain (VSLD), gained sensitivity to cold but lost its heat sensitivity. In hTRPA1 intrinsic tryptophan fluorescence studies, cold and heat evoked rearrangement of VSLD and the C-terminus domain distal to the transmembrane pore domain S5–S6 (CTD). In whole-cell electrophysiology experiments, replacement of the CTD located cysteines 1021 and 1025 with alanine modulated hTRPA1 cold responses. It is proposed that hTRPA1 CTD harbors cold and heat sensitive domains allosterically coupled to the S5–S6 pore region and the VSLD, respectively

Pioglitazone, a specific ligand of peroxisome proliferator-activated receptor-gamma, protects pancreas against acute cerulein-induced pancreatitis

AIM: To determine the effect of pioglitazone, a specific peroxisome proliferator-activated receptor-γ (PPARγ) ligand, on the development of acute pancreatitis (AP) and on the expression of heat shock protein 70 (HSP70) in the pancreas. METHODS: AP was induced in rats by subcutaneous infusion of cerulein for 5 h. Pancreatic blood flow was measured by laser Doppler flowmetry. Plasma lipase activity, interleukin-1β (IL-1β) and IL-10 were determined. Pancreatic weight and histology were evaluated and pancreatic DNA synthesis and blood flow as well as pancreatic mRNA for IL-1β and HSP70 were assessed in rats treated with pioglitazone alone or in combination with cerulein. RESULTS: Pioglitazone administered (10-100 mg/kg i.g.) 30 min before cerulein, attenuated dose-dependently the pancreatic tissue damage in cerulein-induced pancreatitis (CIP) as demonstrated by the improvement of pancreatic histology, reduction in plasma lipase activity, plasma concentration of pro-inflammatory IL-1β and its gene expression in the pancreas and attenuation of the pancreatitis-evoked fall in pancreatic blood flow. CIP increased pancreatic HSP70 mRNA and protein expression in the pancreas and this effect was enhanced by pioglitazone treatment. CONCLUSION: Pioglitazone attenuates CIP and the beneficial effect of this pioglitazone is multifactorial probably due to its anti-inflammatory activities, to the suppression of IL-1β and to the overexpression of HSP70. PPARγ ligands could represent a new therapeutic option in the treatment of AP

Pretreatment with obestatin inhibits the development of acetic acid-induced colitis in rats

Introduction: Obestatin is a 23-amino acid peptide derived from proghrelin, a common prohormone for ghrelin and obestatin. Previous studies have shown that obestatin exhibits some protective and therapeutic effects in the pancreas and stomach. The aim of this study was to examine the effect of pretreatment with obestatin on the development of acetic acid-induced colitis. Material and methods: Studies were performed on Wistar rats. Before induction of colitis, rats were treated intraperitoneally with saline or obestatin, administered twice at a dose of 4, 8 or 16 nmol/kg/dose. The first dose of saline or obestatin was administered 8 h before the induction of colitis, the second one 7 h after the first dose. Colitis was induced by enema with 1 ml of 4% acetic acid solution. The severity of colitis was assessed 1 or 24 h after administration of enema. Results: Pretreatment with obestatin administered at a dose of 8 or 16 nmol/ kg/dose significantly reduced the area of mucosal damage evoked by enema with acetic acid (p < 0.05). This effect was accompanied by an improvement of mucosal blood flow and DNA synthesis in the colon. Moreover, obestatin administered at a dose of 8 or 16 nmol/kg/dose significantly reduced mucosal concentration of IL-1β and activity of myeloperoxidase (p < 0.05). Conclusions: Pretreatment with obestatin exhibited a protective effect in the colon, leading to a reduction of colonic damage in acetic acid-induced colitis. This effect was associated with an improvement of mucosal blood flow, an increase in mucosal cell proliferation, and a decrease in local inflammation

String Dualities in the Presence of Anomalous U(1) Symmetries

Anomalous U(1) gauge symmetries in type II orientifold theories show some unexpected properties. In contrast to the heterotic case, the masses of the gauge bosons are in general of order of the string scale even in the absence of large Fayet-Iliopoulos terms. Despite this fact, the notion of heterotic-type II orientifold duality remains a useful concept, although this symmetry does not seem to hold in all cases considered. We analyse the status of this duality symmetry, clarify the properties of anomalous U(1) gauge symmetry in the orientifold picture and comment on the consequences for phenomenological applications of such anomalous gauge symmetries.Comment: 23 pages, LaTeX2