Ionization Phenomena in a Gas-Particle Plasma

Particles in a plasma can appreciably change the electron density from the value it would assume if the particles were not present. The case of pure particle ionization, in which there is only thermionic emission from the particles and no gas ionization, is first considered. It is established that the potential and the charge distributions can be divided into a strong shielding regime, in which most of the free electrons are packed close to the particle surfaces in regions of high potential, and its direct opposite, a weak shielding regime. In both regimes, the free-electron content of the plasma is most readily altered by variations in the particle size, rather than in the work function or particle temperature. The suppression of one form of ionization by the other when both particle and gas contribution to the electron density are comparable is next investigated. In the case of gaseous ionization enhancement it is shown that, if the thermionically emitting particles are hotter than the gas, the electron temperature will also be higher than that of the gas and the gaseous ionization thereby enhanced. Lastly, it is shown that in some transient situations, the particles are able to control the time rate of change of the electron density

The Time-Course of Lexical and Structural Processes in Sentence Comprehension

Online sentence comprehension involves multiple types of cognitive processes: lexical processes such as lexical access, which call on the user's knowledge of the meaning of words in the language, and structural processes such as the integration of incoming words into an emerging representation. In this article, we investigate the temporal dynamics of lexical access and syntactic integration. Unlike much previous work that has relied on temporary ambiguity to investigate this question, we manipulate the frequency of the verb in unambiguous structures involving a well-studied syntactic complexity manipulation (subject- vs. object-extracted clefts). The results demonstrate that for high-frequency verbs, the difficulty of reading a more structurally complex object-extracted cleft structure relative to a less structurally complex subject-extracted cleft structure is largely experienced in the cleft region, whereas for low-frequency verbs this difficulty is largely experienced in the postcleft region. We interpret these results as evidence that some stages of structural processing follow lexical processing. Furthermore, we find evidence that structural processing may be delayed if lexical processing is costly, and that the delay is proportional to the difficulty of the lexical process. Implications of these results for contemporary accounts of sentence comprehension are discussed

Risks of International Projects: Reward or Folly?

Assessing and managing risk is a complex and critical task for international construction projects that support new business ventures. Indeed, it could be argued that the word "risk" and the term "international projects" could be used interchangeably. Driven by such factors as new markets, domestic competition, and trade liberalization, U.S. owners and contractors have in recent years aggressively pursued international business opportunities and projects. International work requires owners to assess a diverse set of political, geographic, economic, environmental, regulatory, and cultural risk factors when contemplating an international capital project. In addition, contractors must consider a similar set of risk factors in determining whether to undertake such projects, and how to price and schedule the work if they do. A limited amount of research has been undertaken to address these issues, and current efforts to assess and evaluate the risks associated with international construction are fragmented and fail to provide adequate assistance to project managers. Can risks be systematically addressed and mitigated on these types of projects or is it folly to attempt this process? This paper will report the results of a research project focused on international projects sponsored by the Center for Construction Industry Studies (CCIS), the Construction Industry Institute (CII) and the Project Management Institute (PMI). This research included input from over 100 industry experts representing 58 organizations. Data from 65 international projects, with a total cost of approximately $27 billion (U.S.) were analyzed. Key risk issues and a management approach to help mitigate risks will be presented. Included in that discussion will be the International Project Risk Assessment (IPRA) tool developed in collaboration with industry. This management tool provides a systematic method to identify, assess, and determine the relative importance of international-specific risks across the project’s life cycle. The reward of risk management on international ventures will be explored. How industries other than construction can gain from this research will be outlined

Front End Planning of Railway Projects

ABSTRACT Infrastructure capital projects are at the center of efforts to invest in the recovery of the economy, both domestically and internationally, and are seen as a primary growth engine of the construction industry today. Sadly, many of these projects are unsuccessful due to poor early project planning. Front End Planning (FEP) is a critical process for uncovering project unknowns, while developing adequate scope definition and a structured approach for the project execution process. FEP assists in identifying and mitigating issues such as right-of-way concerns, utility adjustments, environmental hazards, logistic problems, permitting requirements and so on. This paper will outline research funded by the Construction Industry Institute (CII) focused on front end planning of infrastructure projects. This investigation, which includes input from domestic and foreign planning experts from over 30 organizations using as reference over 60 capital projects, provides an understanding of the critical issues that must be addressed during FEP of infrastructure projects, particularly as applied to rail projects. A new risk management tool for FEP, called the Project Definition Rating Index (PDRI) for Infrastructure Projects, will be shown. Critical success factors for FEP of railway and infrastructure projects will be shared, including key planning process steps, along with guidance to practitioners involved in planning these types of projects

Assessing the Performance of Two-Step Design-Build Procurement

ABSTRACT Design-Build (DB) is an alternative project delivery system that is distinguished by a DB team acting as the single point of responsibility for a project where the design and construction phases overlap. There are two main methods used to procure DB services: single-step procurement and two-step procurement. This paper focuses on quantifying the resource expenditures of two-step DB projects through investigating both pre-award and post-award metrics. The pre-award metrics include the costs related to the request for qualification (RFQ) and request for proposal (RFP) phases, while the post-award metrics focus specifically on overall project performance (e.g. project cost, delivery schedule, etc.) The authors developed a detailed survey to collect data from public building projects procured using twostep design-build procurement methods. This paper presents preliminary results, specifically the data stemming from six two-step DB projects completed after 2005 and with total project costs ranging from $20.5 million to$299 million. Results of the analysis show the total cost to industry to develop full proposals is about one percent of the total project cost. Additionally, the total proposal cost to DB teams was reduced significantly due to stipend incentives offered by the owners. BACKGROUND The design-build (DB) alternative project delivery method has become increasingly common in the architecture, engineering, and construction (AEC) industry. DB is distinguished by a single point of responsibility for the design and construction of a facility. There are two main methods used to procure DB services: single-step procurement and two-step procurement. There is a lack of information comparing the performance of these two main DB procurement methods. Additionally, major stakeholders in the AEC industry are concerned that the singlestep DB process might be placing an unfair burden on the industry, particularly because it typically requires a large number of DB teams to develop costly proposals (ECB 2012). As a result, the Design-Build Institute of America (DBIA) and its partner organizations organized a research effort to study and compare the resource expenditures of single-step and two-step DB procurement. This paper focuses specifically on providing a performance analysis of the two-step DB procuremen

Changing Project Delivery Strategy: An Implementation Framework

For organizations such as departments of transportation, other public agencies, or private companies, adopting a new approach to procure services for delivery of construction projects requires significant organizational changes; modifications to both their work processes and existing organizational structures may be needed. These adjustments, encompassing many different aspects of the organization’s interests, must occur for the change initiative to be successfully put into practice. Research at the Center for Construction Industry Studies is investigating the adoption of integrated project delivery methods within the transportation project sector to better understand the dynamics of this change. This paper will present findings from a study of Public Owner organizations that have implemented the design-build method for delivering highway projects. Using as a case study the new $1.3 billion SH 130 tolled expressway project in Central Texas, we have analyzed project documentation, held a workshop and conducted 39 interviews with individuals affiliated with owner, legal, engineering consultants, and contractors. Findings suggest that project representatives institutionalize practices and routines connected to the new approach by adapting to new challenges, rather than “overwriting” previously existing practices. Consequently, the institutionalization of innovative approaches to project delivery happens concurrently with a deinstitutionalization of the previous approaches. This concurrency produces different effects on the project environment, depending on the mediating action of some emerging practices and the perspective of the involved parties. Building upon these findings, we have developed a conceptual framework for helping Owner organizations implement a change in their project delivery strategy. In the context of this paper, an Owner’s project delivery strategy is defined as the set of project delivery methods that are adopted for delivering capital projects. We further refined this framework by making a comparative study of four transportation projects in the United States. In addition, 35 experts in the implementation of the design-build method for transportation projects participated in a Delphi study in order to validate the developed framework. Findings from these studies, including application to the construction industry and to other industries will be presented in this paper

The Passing of Print

This paper argues that ephemera is a key instrument of cultural memory, marking the things intended to be forgotten. This important role means that when ephemera survives, whether accidentally or deliberately, it does so despite itself. These survivals, because they evoke all those other objects that have necessarily been forgotten, can be described as uncanny. The paper is divided into three main sections. The first situates ephemera within an uncanny economy of memory and forgetting. The second focuses on ephemera at a particular historical moment, the industrialization of print in the nineteenth century. This section considers the liminal place of newspapers and periodicals in this period, positioned as both provisional media for information as well as objects of record. The third section introduces a new configuration of technologies – scanners, computers, hard disks, monitors, the various connections between them – and considers the conditions under which born-digital ephemera can linger and return. Through this analysis, the paper concludes by considering digital technologies as an apparatus of memory, setting out what is required if we are not to be doubly haunted by the printed ephemera within the digital archive

The association of affective disorders and facial scarring: systematic review and meta-analysis

Background: Facial scarring can have a dramatic effect on a patient’s psychological health and wellbeing and present unique management challenges. This patient population remains poorly characterised in the contemporary literature. Aims: To evaluate the prevalence of, and risk factors associated with affective disorders in adult patients with facial scars. Methods: A systematic review was conducted using a protocol registered with PROSPERO and in line with the PRISMA statement. A comprehensive search of the literature was conducted using PubMed, MEDLINE, EMBASE, PSYCHInfo and The Cochrane Library. Results: Twenty one studies were included, with a total of 2,394 participants. Using a random effects model, the weighted pooled prevalence of anxiety was 26.1% (95% CI 17.9%-36.3%) and the weighted pooled prevalence of depression was 21.4% (95% CI 15.4%-29.0%). Studies identified female gender, past psychiatric history and violent causation as factors associated with anxiety and depression. Limitations: Included studies were limited to those published in peer reviewed journals. Longitudinal trends in both anxiety and depression were limited by a short duration of follow up. Conclusions: There is a high and persistent burden of affective disorders in patients with facial scars. Additional research is required to further characterise this population and develop effective management strategies

Grouping in object recognition: The role of a Gestalt law in letter identification

The Gestalt psychologists reported a set of laws describing how vision groups elements to recognize objects. The Gestalt laws “prescribe for us what we are to recognize ‘as one thing’” (Köhler, 1920). Were they right? Does object recognition involve grouping? Tests of the laws of grouping have been favourable, but mostly assessed only detection, not identification, of the compound object. The grouping of elements seen in the detection experiments with lattices and “snakes in the grass” is compelling, but falls far short of the vivid everyday experience of recognizing a familiar, meaningful, named thing, which mediates the ordinary identification of an object. Thus, after nearly a century, there is hardly any evidence that grouping plays a role in ordinary object recognition. To assess grouping in object recognition, we made letters out of grating patches and measured threshold contrast for identifying these letters in visual noise as a function of perturbation of grating orientation, phase, and offset. We define a new measure, “wiggle”, to characterize the degree to which these various perturbations violate the Gestalt law of good continuation. We find that efficiency for letter identification is inversely proportional to wiggle and is wholly determined by wiggle, independent of how the wiggle was produced. Thus the effects of three different kinds of shape perturbation on letter identifiability are predicted by a single measure of goodness of continuation. This shows that letter identification obeys the Gestalt law of good continuation and may be the first confirmation of the original Gestalt claim that object recognition involves grouping

Exposure to Stress and Air Pollution from Bushfires during Pregnancy: Could Epigenetic Changes Explain Effects on the Offspring?

Due to climate change, bushfires are becoming a more frequent and more severe phenomenon which contributes to poor health effects associated with air pollution. In pregnancy, environmental exposures can have lifelong consequences for the fetus, but little is known about these consequences in the context of bushfire smoke exposure. In this review we summarise the current knowledge in this area, and propose a potential mechanism linking bushfire smoke exposure in utero to poor perinatal and respiratory outcomes in the offspring. Bushfire smoke exposure is associated with poor pregnancy outcomes including reduced birth weight and an increased risk of prematurity. Some publications have outlined the adverse health effects on young children, particularly in relation to emergency department presentations and hospital admissions for respiratory problems, but there are no studies in children who were exposed to bushfire smoke in utero. Prenatal stress is likely to occur as a result of catastrophic bushfire events, and stress is known to be associated with poor perinatal and respiratory outcomes. Changes to DNA methylation are potential epigenetic mechanisms linking both smoke particulate exposure and prenatal stress to poor childhood respiratory health outcomes. More research is needed in large pregnancy cohorts exposed to bushfire events to explore this further, and to design appropriate mitigation interventions, in this area of global public health importance.Vanessa Murphy is supported by an Investigator Grant from the Medical Research Future Fund (grant ID 1196252)