451 research outputs found
Implications of 'Lock-in' on Public Sector Project Management in a Small Island Development State
The concept of âLock-Inâ, or the escalating cost of overcommitment on a project to a failing course of action, has unforeseeable implications in project management. This paper presents a case study on the occurrence and consequences of lock-in within the context of public sector housing projects in a small island developing state (SIDS). It demonstrates that cost overruns continue beyond the commissioning phase and throughout the projectâs lifecycle, even though technical contingencies were implemented to deliver the intended project benefits. The findings unpack the implications of political expediency as a strategic tool mobilised to supersede proper technical decision-making prior to project execution. It concludes that project practitionersâ commitment to select and continue with a sub-optimal project can lead to the implementation of ineffective solutions to justify their actions, resulting in failed outcomes with negative social consequences. This research helps to advance project management knowledge in the us-er/operation phase, because previous scholarly work was limited to investigating lock-in from project conceptualisation to the commissioning phase
When Parallel Schools of Thought Fail to Converge: The Case of Cost Overruns in Project Management
This paper investigates the conflicting and contrasting views between two prominent schools of thought (SOT), the conventional project management empirical school and the incoming behavioural and psychological sciences, to explain the cost overrun phenomenon in transportation infrastructure projects. Although theories within these SOTs seem to coexist and are used interchangeably, there exists a widening knowledge gap that leads to conflicting and contrasting ideological views. In this paper, we contend that there is a lack of a cross-fertilisation mechanism to fuse and co-join contemporary theories on cost overruns. This has led to the encapsulation and fragmented adhocracy in theory building. Utilising a critical review approach, this study proposes the concepts of ideological distancing and encapsulation between âempiricismâ and âbehaviouralâ SOTs as the focus of analyses for understanding the root causes of cost overruns in project studies. The study showed that the extant debate on cost overruns is limited and divergent, effectively contributing to the problem of continued expansion and non-convergence of theories that maintain parallel identities. This creates a space for inquiry, reflecting, theorising, and debating for the convergence of SOTs on cost overrun research and theories on what can be deemed project knowledge. This paper contributes to extant project studies by identifying the need for convergence and co-joining theories with different epistemes through causal linkages. Consequently, this will improve the public sectorâs infrastructure policymaking by exposing the theoretical limitations of the current ad hoc manner and application of project management concepts based on the project professionalsâ bounded decision-making rationalities
A Novel Xenomonitoring Technique Using Mosquito Excreta/Feces for the Detection of Filarial Parasites and Malaria
Given the continued successes of the worldâs lymphatic filariasis (LF) elimination programs and the growing successes of many malaria elimination efforts, the necessity of low cost tools and methodologies applicable to long-term disease surveillance is greater than ever before. As many countries reach the end of their LF mass drug administration programs and a growing number of countries realize unprecedented successes in their malaria interven- tion efforts, the need for practical molecular xenomonitoring (MX), capable of providing surveillance for disease recrudescence in settings of decreased parasite prevalence is increasingly clear. Current protocols, however, require testing of mosquitoes in pools of 25 or fewer, making high-throughput examination a challenge. The new method we present here screens the excreta/feces from hundreds of mosquitoes per pool and provides proof- of-concept for a practical alternative to traditional methodologies resulting in significant cost and labor savings
The influence of optimism bias on time and cost on construction projects
The unresolved scholarly debate to curtail cost and time performances in projects has led to alternate solutions, departing from the dominant technical school of thought to include concepts from behavioural sciences. In this paper, we consider the psychological effect, namely optimism bias, as one of the root causes for delays in cost overruns on projects. The research objectives were to determine the level of bias among project participants, rank time and cost overrun causes according to the participantsâ bias score and establish a mitigation strategy to curb potential delays and cost overrun impacts based on the bias scores obtained. A literature survey was conducted to determine causal factors contributing to delays and cost overruns linked to optimism bias. Through a pilot survey of three semi-structured interviews, eighty factors obtained from the literature survey were reduced to 24 critical delay and cost overrun factors relevant to Trinidad and Tobago. A questionnaire was subsequently developed seeking construction professionals to rate their bias scores based on an 11-point Likert scale. The research confirms that project planners and decision-makers exhibit moderate levels of optimism bias; however, participants lacked awareness of the impact of optimism bias on projects outcomes. Project location, environmental impacts and historic preservation, and labour disputes are the top three critical factors where project professionals displayed increased optimistic tendencies. It is proposed that contingency âtime windowâ and reference class forecasting be implemented as control mechanisms to mitigate the impacts of time and cost overruns on projects. This research introduces a novel method to account for and measure optimism bias on construction projects. This study adds knowledge into delays and cost overruns causation and provides a foundation for future studies on quantifying psychological effects on projects and enhancing overall project management practices
Rationalizing Critical Cost Overrun Factors on Public Sector Housing Programmes
The cost overrun phenomenon on projects worldwide creates a major source of risk that warrants investigation. The prevailing factor school of thought provides strong empirical evidence that critical factors contributing to cost overruns are both context-specific and project-specific. Although many studies have been conducted identifying factors and causes of cost overruns, very few studies have investigated root causes. Additionally, a limited body of knowledge is available within the context of Small Island Development States (SIDS). To fill this gap, the objectives of this study were to identify and determine the main critical factors contributing to the cost overrun phenomenon in public sector social housing programmes (PSSHPs). These selected factors were thereafter categorized under leading root causes, and their severity was determined based on primary stakeholdersâ perspectives. One hundred and twenty-three factors were identified from the literature, of which forty-one critical factors were extracted and grouped under four root causes based on a pilot survey of relevant public sector housing experts in the Trinidadian and Jamaican construction sectors. These refined factors and root causes were formulated into a questionnaire survey. One hundred and five responses were obtained from professionals who had a minimum of five yearsâ experience in various phases of public housing delivery. The severity of these critical factors was evaluated, ranked, and categorized using the relative importance index (RII) approach. The findings uncovered the leading root cause, which is political in nature. The top five critical factors are the selection of politically aligned contractors, the intentional design of inadequate contracts, the project actors' deliberately underestimating costs, the partisan project management team, and strategic misrepresentation. These findings are unique to SIDS and contribute to knowledge to reframe contemporary project management practices, which focus mainly on technical causes. Finally, as existing technical solutions are ineffective in curbing cost overruns in PSSHPs, these findings also inform public sector policymakers to focus on prioritization, control, and mitigation of political risks in formulating effective governance mechanisms
Toll-Like Receptor 9-Dependent Macrophage Activation by Entamoeba histolytica DNA
Activation of the innate immune system by bacterial DNA and DNA of other invertebrates represents a pathogen recognition mechanism. In this study we investigated macrophage responses to DNA from the intestinal protozoan parasite Entamoeba histolytica. E. histolytica genomic DNA was purified from log-phase trophozoites and tested with the mouse macrophage cell line RAW 264.7. RAW cells treated with E. histolytica DNA demonstrated an increase in levels of tumor necrosis factor alpha (TNF-α) mRNA and protein production. TNF-α production was blocked by pretreatment with chloroquine or monensin. In fact, an NF-ÎșB luciferase reporter assay in HEK cells transfected with human TLR9 demonstrated that E. histolytica DNA signaled through Toll-like receptor 9 (TLR9) in a manner similar to that seen with CpG-ODN. Immunofluorescence assays confirmed NF-ÎșB activation in RAW cells, as seen by nuclear translocation of the p65 subunit. Western blot analysis demonstrated mitogen-activated protein kinase activation by E. histolytica DNA. E. histolytica DNA effects were abolished in MYD88â/â mouse-derived macrophages. In the context of disease, immunization with E. histolytica DNA protected gerbils from an E. histolytica challenge infection. Taken together, these results demonstrate that E. histolytica DNA is recognized by TLR9 to activate macrophages and may provide an innate defense mechanism characterized by the induction of the inflammatory mediator TNF-α
Tumor Necrosis Factor-α and Muc2 Mucin Play Major Roles in Disease Onset and Progression in Dextran Sodium Sulphate-Induced Colitis
The sequential events and the inflammatory mediators that characterize disease onset and progression of ulcerative colitis (UC) are not well known. In this study, we evaluated the early pathologic events in the pathogenesis of colonic ulcers in rats treated with dextran sodium sulfate (DSS). Following a lag phase, day 5 of DSS treatment was found clinically most critical as disease activity index (DAI) exhibited an exponential rise with severe weight loss and rectal bleeding. Surprisingly, on days 1-2, colonic TNF-α expression (70-80-fold) and tissue protein (50-fold) were increased, whereas IL-1ÎČ only increased on days 7-9 (60-90-fold). Days 3-6 of DSS treatment were characterized by a prominent down regulation in the expression of regulatory cytokines (40-fold for IL-10 and TGFÎČ) and mucin genes (15-18 fold for Muc2 and Muc3) concomitant with depletion of goblet cell and adherent mucin. Remarkably, treatment with TNF-α neutralizing antibody markedly altered DSS injury with reduced DAI, restoration of the adherent and goblet cell mucin and IL-1ÎČ and mucin gene expression. We conclude that early onset colitis is dependent on TNF-α that preceded depletion of adherent and goblet cell mucin prior to epithelial cell damage and these biomarkers can be used as therapeutic targets for UC
Oviposition Site Selection by the Dengue Vector Aedes aegypti and Its Implications for Dengue Control
Controlling the mosquito Aedes aegypti is of public health importance because, at present, it is the only means to stop dengue virus transmission. Implementing successful mosquito control programs requires understanding what factors regulate population abundance, as well as anticipating how mosquitoes may adapt to control measures. In some species of mosquitoes, females choose egg-laying sites to improve the survival and growth of their offspring, a behavior that ultimately influences population distribution and abundance. In the current study, we tested whether Ae. aegypti actively choose the containers in which they lay their eggs and determined what cues are most relevant to that process. We also explored whether females select containers that provide the most food for their larval progeny. Surprisingly, egg-laying females were most attracted to sites containing other immature Ae. aegypti, rather than to sites containing the most food. We propose that this behavior may contribute to density-dependent competition for food among larvae and play a larger role than previously thought in regulating Ae. aegypti populations. We recommend that accounting for, and even taking advantage of, this natural behavior will lead to more effective strategies for dengue prevention
Global genetic diversity of Aedes aegypti
Mosquitoes, especially Aedes aegypti, are becoming important models for studying invasion biology. We characterized genetic variation at 12 microsatellite loci in 79 populations of Ae. aegypti from 30 countries in six continents, and used them to infer historical and modern patterns of invasion. Our results support the two subspecies Ae. aegypti formosus and Ae. aegypti aegypti as genetically distinct units. Ae. aegypti aegypti populations outside Africa are derived from ancestral African populations and are monophyletic. The two subspecies co-occur in both East Africa (Kenya) and West Africa (Senegal). In rural/forest settings (Rabai District of Kenya), the two subspecies remain genetically distinct, whereas in urban settings, they introgress freely. Populations outside Africa are highly genetically structured likely due to a combination of recent founder effects, discrete discontinuous habitats and low migration rates. Ancestral populations in sub-Saharan Africa are less genetically structured, as are the populations in Asia. Introduction of Ae. aegypti to the New World coinciding with trans-Atlantic shipping in the 16th to 18th centuries was followed by its introduction to Asia in the late 19th century from the New World or from now extinct populations in the Mediterranean Basin. Aedes mascarensis is a genetically distinct sister species to Ae. aegypti s.l. This study provides a reference database of genetic diversity that can be used to determine the likely origin of new introductions that occur regularly for this invasive species. The genetic uniqueness of many populations and regions has important implications for attempts to control Ae. aegypti, especially for the methods using genetic modification of populations.Centro de Estudios Parasitológicos y de Vectore
Global genetic diversity of Aedes aegypti
Mosquitoes, especially Aedes aegypti, are becoming important models for studying invasion biology. We characterized genetic variation at 12 microsatellite loci in 79 populations of Ae. aegypti from 30 countries in six continents, and used them to infer historical and modern patterns of invasion. Our results support the two subspecies Ae. aegypti formosus and Ae. aegypti aegypti as genetically distinct units. Ae. aegypti aegypti populations outside Africa are derived from ancestral African populations and are monophyletic. The two subspecies co-occur in both East Africa (Kenya) and West Africa (Senegal). In rural/forest settings (Rabai District of Kenya), the two subspecies remain genetically distinct, whereas in urban settings, they introgress freely. Populations outside Africa are highly genetically structured likely due to a combination of recent founder effects, discrete discontinuous habitats and low migration rates. Ancestral populations in sub-Saharan Africa are less genetically structured, as are the populations in Asia. Introduction of Ae. aegypti to the New World coinciding with trans-Atlantic shipping in the 16th to 18th centuries was followed by its introduction to Asia in the late 19th century from the New World or from now extinct populations in the Mediterranean Basin. Aedes mascarensis is a genetically distinct sister species to Ae. aegypti s.l. This study provides a reference database of genetic diversity that can be used to determine the likely origin of new introductions that occur regularly for this invasive species. The genetic uniqueness of many populations and regions has important implications for attempts to control Ae. aegypti, especially for the methods using genetic modification of populations.Centro de Estudios Parasitológicos y de Vectore
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