Reliability and tolerance comparison in water supply networks

The final publication is available at Springer via http://dx.doi.org/10.1007/s11269-010-9753-2Urban water supply is a high priority service and so looped networks are extensively used in order to considerably reduce the number of consumers affected by a failure. Looped networks may be redundant in connectivity and capacity. The concept of reliability has been introduced in an attempt to quantitatively measure the possibility of maintaining an adequate service for a given period. Numerous researchers have considered reliability as a measure of redundancy. This concept is usually implicit, but some researchers have even stated it explicitly. This paper shows why reliability cannot be considered a measure of redundancy given that branched networks can achieve high values of reliability and this would deny the fact that a looped network is more reliable than a branched network with a similar layout and size. To this end the paper discusses two quantitative indices for measuring expected network behavior: reliability and tolerance. These indices are calculated and a comparison is made between looped, branched, and mixed networks. © 2011 Springer Science+Business Media B.V.The authors wish to acknowledge the support received from project IDAWAS, DPI2009-11591, of the Directorate-General of Research at the Spanish Ministry of Education, the grant PAID-02-09 for a stay at the Universidad Politecnica de Valencia by the first author, and a grant MAEC-AECI 0000202066 awarded to the second author by the Ministerio de Asuntos Exteriores y Cooperacion of Spain. The use of English in this paper was revised by John Rawlins; and the revision was funded by the Universidad Politecnica de Valencia, Spain.Martínez-Rodríguez, JB.; Montalvo Arango, I.; Izquierdo Sebastián, J.; Pérez García, R. (2011). Reliability and tolerance comparison in water supply networks. Water Resources Management. 25(5):1437-1448. https://doi.org/10.1007/s11269-010-9753-2S14371448255Bao Y, Mays LW (1990) Model for water distribution system reliability. J Hydraul Eng ASCE 116(9):1119–1137Bouchart F, Goulter I (1991) Reliability improvements in design of water distribution networks recognizing valve location. Water Resour Res 27(12):3029–3040Carrión A, Solano H, Gamiz ML, Debón A (2010) Evaluation of the reliability of a water supply network from right-censored and left-truncated break data. Water Resour Manag, Springer Sci 24:2917–2935. Published online: 28 January 2010Chiong C (1985) Optimización de redes cerradas, Doctoral Thesis, CIH-CUJAE, Havana (in Spanish)Christodoulou SE (2010) Water network assessment and reliability analysis by use of survival analysis. Water Resour Manag, Springer Sci, Published online: 19 June 2010Cullinane MJ, Lansey KE, Mays LW (1992) Optimization-availability-based design of water distribution networks. J Hydraul Eng ASCE 118(3):420–441Duan N, Mays LW, Lansey KE (1990) Optimal reliability-based design of pumping and distribution systems. J Hydraul Eng ASCE 116(2):249–268Goulter I (1992) Systems analysis in water distribution network design: from theory to practice. J Water Resour Plan Manage ASCE 118(3):238–248Goulter I (1993) Modern concepts of a water distribution system. Policies for improvement of networks with shortcomings. In: Cabrera E, Martínez F (eds) Water supply systems: state of the art and future trends, Valencia (Spain). Comput Mech Publ, Southampton, pp 121–138Goulter I, Bouchart F (1990) Reliability-constrained pipe network model. J Hydraul Eng ASCE 116(2):211–229Gupta R, Bhave R (1994) Reliability analysis of water distribution systems. J Environ Eng ASCE 120(2):447–460Jacobs P, Goulter I (1991) Estimation of maximum cut-set size for water network failure. J Water Resour Plan Manage ASCE 117(5):588–605Jowitt P, Xu C (1993) Predicting pipe failure effects in water distribution networks. J Water Resour Plan Manage ASCE 119(l):18–31Kalungi P, Tanyimboh TT (2003) Redundancy model for water distribution systems. Rel Eng Syst Safety 82(3):275–286Khomsi D, Walters GA, Thorley ARD, Ouazar D (1996) Reliability tester for water-distribution networks. J Comput Civ Eng ASCE 10(l):10–9Lansey K, Duan N, Mays LW, Tung YK (1989) Water distribution system design under uncertainty. J Water Resour Plan Manage ASCE 115(5):630–645Loganathan GV, Shah MP, Sherali HP (1990) A two-phase network design heuristic for minimum cost water distribution systems under a reliability constraint. Eng Optim 15(4):311–336Martínez JB (2007) Quantifying the economy of water supply looped networks. J Hydraul Eng ASCE 133(1):88–97Martínez JB (2010) Cost and reliability comparison between branched and looped water supply networks. J Hydroinform IWA 12(2):150–160Morgan DR, Goulter IC (1985) Optimal urban water distribution design. Water Resour Res 21(5):642–652Park H, Leibman J (1993) Redundancy-constrained minimum-cost design of water distribution networks. J Water Resour Plan Manage ASCE 119(l):83–98Pinto J, Varum H, Bentes I, Agarwal J (2010) A theory of vulnerability of water pipe network. Water Resour Manag 24:4237–4254. Springer Science, Published online: 6 May 2010Quimpo R, Shamsi U (1991) Reliability-based distribution system maintenance. J Water Resour Plan Manage ASCE 117(3):321–339Su Y, Mays LW, Duan N, Lansey K (1987) Reliability based optimization model for water distribution systems. J Hydraul Eng ASCE 113(12):1539–1556Tanyimboh TT, Tabesh M, Burrows R (2001) Appraisal of source head methods for calculating reliability of water distribution networks. J Water Resour Plan Manage ASCE 127(4):206–213Walski TM, Weiler JS, Culver T (2006) Using criticality analysis to identify impact of valve location. In: Proc 8th annual water distrib systems analysis symposium, August 27–30, Cincinnati, Ohio, USA,Walters GA, Knezevic J (1989) Discussion of ‘Reliability based optimization model for water distribution systems’ by Su, Y., Mays, L. W. , Duan, N., and Lansey, K. J Hydraul Eng ASCE 115(8):1157–1158Xu C, Goulter I (1997) Simulation-based optimal design of reliable water distribution networks. In: Zayegh A (ed) Proc 3rd int conf on modeling and simulation. Victoria University of Technology, Melbourne, pp 107–112Xu C, Goulter I (1998) Probabilistic model for water distribution reliability. J Water Resour Plan Manage ASCE 124(4):218–228Xu C, Goulter I (1999) Reliability based optimal design of water distribution networks. J Water Resour Plan Manage ASCE 125(6):352–362Xu C, Goulter I (2000) A model for optimal design of reliable water distribution networks. In: Blain WR, Brebbia CA (eds) Hydraulic engineering software VIII. WIT, Southampton, pp 71–8

It’s Not the Left: Ideology and Protest Participation in Old and New Democracies

Multiple studies in political science consistently hold that left-wing ideology renders individuals more prone to protest behavior. However, the familiar association between left-wing ideology and protesting is not empirically corroborated in all democratic nations. Building on existing theoretical principles and applying them to diverse political contexts, this paper sheds light on puzzling variation in protest behavior across new and old democracies. It argues that it is not the left that engenders protest. Instead, we demonstrate that which political camp engages in protest behavior depends on its historical legacies and cultural liberalism. Historical legacies reflect the ideological configuration at democratization. Protesting tends to be more common in the ideological camp that opposed the pre-democratic political order. Simultaneously, it is culturally liberal individuals that more likely embrace protest participation, independent of their left-right identification. These theoretical expectations are supported through survey data analyses, explaining contrasting inter- and intra-regional variation in European democracies

Chemokine CXCL4 interactions with extracellular matrix proteoglycans mediate widespread immune cell recruitment independent of chemokine receptors

Leukocyte recruitment from the vasculature into tissues is a crucial component of the immune system but is also key to inflammatory disease. Chemokines are central to this process but have yet to be therapeutically targeted during inflammation due to a lack of mechanistic understanding. Specifically, CXCL4 (Platelet Factor 4, PF4) has no established receptor that explains its function. Here, we use biophysical, in vitro, and in vivo techniques to determine the mechanism underlying CXCL4-mediated leukocyte recruitment. We demonstrate that CXCL4 binds to glycosaminoglycan (GAG) sugars on proteoglycans within the endothelial extracellular matrix, resulting in increased adhesion of leukocytes to the vasculature, increased vascular permeability, and non-specific recruitment of a range of leukocytes. Furthermore, GAG sulfation confers selectivity onto chemokine localization. These findings present mechanistic insights into chemokine biology and provide future therapeutic targets

Turnaround and failure: resource weaknesses and the rise and fall of Jarvis

Research employing the resource-based view (RBV) has overwhelming focused on the upside of resources, namely those that provide benefit to the firm. However, an emerging research stream suggests that the downside of resources, namely resource weaknesses, may be crucial in gaining a greater understanding of the key factors that contribute to firm performance and the ability to turnaround failing companies. We examine the infamous case of Jarvis, a firm that achieved a turnaround, but then experienced catastrophic failure. In so doing we explore the emergence of resource weaknesses, their nature and ability to combine to create a fatal organisational outcome

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Collagen-Like Proteins in Pathogenic E. coli Strains

The genome sequences of enterohaemorrhagic E. coli O157:H7 strains show multiple open-reading frames with collagen-like sequences that are absent from the common laboratory strain K-12. These putative collagens are included in prophages embedded in O157:H7 genomes. These prophages carry numerous genes related to strain virulence and have been shown to be inducible and capable of disseminating virulence factors by horizontal gene transfer. We have cloned two collagen-like proteins from E. coli O157:H7 into a laboratory strain and analysed the structure and conformation of the recombinant proteins and several of their constituting domains by a variety of spectroscopic, biophysical, and electron microscopy techniques. We show that these molecules exhibit many of the characteristics of vertebrate collagens, including trimer formation and the presence of a collagen triple helical domain. They also contain a C-terminal trimerization domain, and a trimeric α-helical coiled-coil domain with an unusual amino acid sequence almost completely lacking leucine, valine or isoleucine residues. Intriguingly, these molecules show high thermal stability, with the collagen domain being more stable than those of vertebrate fibrillar collagens, which are much longer and post-translationally modified. Under the electron microscope, collagen-like proteins from E. coli O157:H7 show a dumbbell shape, with two globular domains joined by a hinged stalk. This morphology is consistent with their likely role as trimeric phage side-tail proteins that participate in the attachment of phage particles to E. coli target cells, either directly or through assembly with other phage tail proteins. Thus, collagen-like proteins in enterohaemorrhagic E. coli genomes may have a direct role in the dissemination of virulence-related genes through infection of harmless strains by induced bacteriophages

The Rare Earth Elements: demand, global resources, and challenges for resourcing future generations

The rare earth elements (REE) have attracted much attention in recent years, being viewed as critical metals because of China’s domination of their supply chain. This is despite the fact that REE enrichments are known to exist in a wide range of settings, and have been the subject of much recent exploration. Although the REE are often referred to as a single group, in practice each individual element has a specific set of end-uses, and so demand varies between them. Future demand growth to 2026 is likely to be mainly linked to the use of NdFeB magnets, particularly in hybrid and electric vehicles and wind turbines, and in erbium-doped glass fiber for communications. Supply of lanthanum and cerium is forecast to exceed demand. There are several different types of natural (primary) REE resources, including those formed by high-temperature geological processes (carbonatites, alkaline rocks, vein and skarn deposits) and those formed by low-temperature processes (placers, laterites, bauxites and ion-adsorption clays). In this paper, we consider the balance of the individual REE in each deposit type and how that matches demand, and look at some of the issues associated with developing these deposits. This assessment and overview indicate that while each type of REE deposit has different advantages and disadvantages, light rare earth-enriched ion adsorption types appear to have the best match to future REE needs. Production of REE as by-products from, for example, bauxite or phosphate, is potentially the most rapid way to produce additional REE. There are still significant technical and economic challenges to be overcome to create substantial REE supply chains outside China