Bridge pier scour under pressure flow conditions

The probability of pressurized flow conditions occurring in existing bridges is forecast to increase due to possible changes in extreme precipitation, storm surges and flooding predicted under climate change scenarios. The presence of a pressure flow is generally associated with scouring processes in proximity to the bridge. Scouring can also occur around bridge piers, possibly causing infrastructure failure. While there is a vast literature on bridge pier scour and pressure flow scour, only a few studies have investigated their combined effect. This study will provide a new overview of the main features of bridge pier scour under pressurized flow conditions, based on laboratory experiences. Special focus is placed on the analysis of the flow features under pressure and free surface conditions and to the temporal evolution of the scour. A comparison with existing literature data is also conducted. The results highlight the nonlinear nature of scour processes and the need to consider pressurized flow conditions during structural design, as the interaction between pressure flow and the bridge pier strongly influences scour features and leads to scour depths much greater than the sum of the individual scours created only by pressure flow or pier presence

Kinematic Modeling of Separation Compression for Paired Approaches to Closely-Spaced Parallel Runways

In a simultaneous paired approach to closely-spaced parallel runways, a pair of aircraft flies in close proximity on parallel approach paths. The longitudinal separation between the aircraft must be maintained within a range that avoids wake encounters and, if one of the aircraft blunders, avoids collision. To increase operational availability, the approach procedure must accommodate a mixture of aircraft sizes and, consequently, approach speeds. In these procedures, the slower aircraft is placed in the lead position. The faster aircraft maintains separation from the slow aircraft in a dependent operation until final approach and flies independently afterward. Due to the higher approach speed of the fast aircraft, longitudinal separation will decrease during final approach. Therefore, the fast aircraft must position itself before the final approach so that it will remain within the safe range of separation as separation decreases. Given the approach geometry and speed schedule for each aircraft, one can use kinematics to estimate the separation loss between a pair of aircraft. A kinematic model can complement fast-time Monte-Carlo simulations of the approach by enabling a tailored reduction in the variation of starting position for the fast aircraft. One could also implement the kinematic model in ground-based or on-board decision support tools to compute the optimal initial separation for a given pair of aircraft. To better match the auto-coupled flight of real aircraft, the paper derives a kinematic model where the speed schedule is flown using equivalent airspeed. The predicted time of flight using the equivalent airspeed kinematic model compares well against a high-fidelity aircraft simulation performing the same approach. This model also demonstrates a modest increase in the predicted loss of separation when contrasted against a kinematic model that assumes the scheduled speed is true airspeed

Motivation for Air-Launch: Past, Present, and Future

Air-launch is defined as two or more air-vehicles joined and working together, that eventually separate in flight, and that have a combined performance greater than the sum of the individual parts. The use of the air-launch concept has taken many forms across civil, commercial, and military contexts throughout the history of aviation. Air-launch techniques have been applied for entertainment, movement of materiel and personnel, efficient execution of aeronautical research, increasing aircraft range, and enabling flexible and efficient launch of space vehicles. For each air-launch application identified in the paper, the motivation for that application is discussed

Colorants in Cheese Manufacture: Production, Chemistry, Interactions, and Regulation

Colored Cheddar cheeses are prepared by adding an aqueous annatto extract (norbixin) to cheese milk; however, a considerable proportion (∼20%) of such colorant is transferred to whey, which can limit the end use applications of whey products. Different geographical regions have adopted various strategies for handling whey derived from colored cheeses production. For example, in the United States, whey products are treated with oxidizing agents such as hydrogen peroxide and benzoyl peroxide to obtain white and colorless spray‐dried products; however, chemical bleaching of whey is prohibited in Europe and China. Fundamental studies have focused on understanding the interactions between colorants molecules and various components of cheese. In addition, the selective delivery of colorants to the cheese curd through approaches such as encapsulated norbixin and microcapsules of bixin or use of alternative colorants, including fat‐soluble/emulsified versions of annatto or beta‐carotene, has been studied. This review provides a critical analysis of pertinent scientific and patent literature pertaining to colorant delivery in cheese and various types of colorant products on the market for cheese manufacture, and also considers interactions between colorant molecules and cheese components; various strategies for elimination of color transfer to whey during cheese manufacture are also discussed

Between mediatisation and politicisation: The changing role and position of Whitehall press officers in the age of political spin

Despite widespread critiques of ‘political spin’, the way governments engage with the mass media has attracted relatively little empirical attention. There is a small but growing body of research into bureaucracies’ responses to mediatisation from within which have identified tensions between bureaucratic and party political values, but this has not included the United Kingdom. There are concerns that the traditional dividing line between government information and political propaganda has come under increasing pressure as a higher premium is placed on persuasion by both journalists and politicians battling for public attention in an increasingly competitive market. Within Whitehall, the arrival of Labour in 1997 after 18 years in opposition was a watershed for UK government communications, allowing the government to reconfigure its official information service in line with the party political imperative to deploy strategic communications as a defence against increasingly invasive media scrutiny. Public relations, in government as elsewhere, has grown in scale, scope and status, becoming institutionalised and normalised within state bureaucracies, but how has this affected the role, status and influence of the civil servants who conduct media management? Within the system of executive self-regulation of government publicity that is characteristic of Whitehall, government press officers must negotiate a difficult path between the need to inform citizens about the government’s programme, and demands by ministers to deploy privileged information to secure and maintain personal and party advantage in the struggle for power. Taking 1997 as a turning point, and through the voices of the actors who negotiate government news – mainly press officers, but also journalists and special advisers – this article examines the changing role and position of Whitehall press officers in what has become known as the age of political spin, finding that profound and lasting change in the rules of engagement has taken place and is continuing

A Trialectic Framework for Large Group Processes in Educational Action Research: The Case of Academic Development for Syrian Academics in Exile

The term ‘large group process’ (LGP) refers to a range of participatory approaches to community engagement, geared towards exploring and/or identifying solutions to shared issues and problems, and planning change. Primarily used for applied purposes, they can be also used as a method of inductive inquiry in social research, particularly within action research projects. In this methodological paper I outline and critically evaluate an LGP design implemented within an action research project focused on the needs of Syrian academics in exile. The LGP elicited multi-level data from a geographically-dispersed community, while simultaneously constituting a relational learning experience and community action event for the participant population, and therefore aligned with the threefold aims of educational action research. The paper makes three significant contributions: a model for LGP design that elicits participants’ collective and individual meaning frames; a trialectic framework for ensuring that the research, action and learning aspects of educational action research projects are mutually-supporting; and an accompanying orientation to researcher-participant relationships that may help to enhance the epistemological validity, catalytic validity and ethical foundations of projects

The application of precision dosing in the use of sertraline throughout pregnancy for poor and ultra-rapid metaboliser CYP 2C19 subjects: a virtual clinical trial pharmacokinetics study:A virtual clinical trial pharmacokinetics study

Sertraline is known to undergo changes in pharmacokinetics during pregnancy. CYP 2C19 has been implicated in the interindividual variation in clinical effect associated with sertraline activity. However, knowledge of suitable dose titrations during pregnancy and within CYP 2C19 phenotypes is lacking. A pharmacokinetic modeling virtual clinical trials approach was implemented to: (i) assess gestational changes in sertraline trough plasma concentrations for CYP 2C19 phenotypes, and (ii) identify appropriate dose titration strategies to stabilize sertraline levels within a defined therapeutic range throughout gestation. Sertraline trough plasma concentrations decreased throughout gestation, with maternal volume expansion and reduction in plasma albumin being identified as possible causative reasons. All CYP 2C19 phenotypes required a dose increase throughout gestation. For extensive metabolizer (EM) and ultrarapid metabolizer (UM) phenotypes, doses of 100–150 mg daily are required throughout gestation. For poor metabolizers (PM), 50 mg daily during trimester 1 followed by a dose of 100 mg daily in trimesters 2 and 3 are required

Global energy growth is outpacing decarbonization

Recent reports have highlighted the challenge of keeping global average temperatures below 2 °C and—even more so—1.5 °C (IPCC 2018). Fossil-fuel burning and cement production release ~90% of all CO2 emissions from human activities. After a three-year hiatus with stable global emissions (Jackson et al 2016; Le Quéré C et al 2018a ; IEA 2018), CO2 emissions grew by 1.6% in 2017 to 36.2 Gt (billion tonnes), and are expected to grow a further 2.7% in 2018 (range: 1.8%–3.7%) to a record 37.1 ± 2 Gt CO2 (Le Quéré et al 2018b). Additional increases in 2019 remain uncertain but appear likely because of persistent growth in oil and natural gas use and strong growth projected for the global economy. Coal use has slowed markedly in the last few years, potentially peaking, but its future trajectory remains uncertain. Despite positive progress in ~19 countries whose economies have grown over the last decade and their emissions have declined, growth in energy use from fossil-fuel sources is still outpacing the rise of low-carbon sources and activities. A robust global economy, insufficient emission reductions in developed countries, and a need for increased energy use in developing countries where per capita emissions remain far below those of wealthier nations will continue to put upward pressure on CO2 emissions. Peak emissions will occur only when total fossil CO2 emissions finally start to decline despite growth in global energy consumption, with fossil energy production replaced by rapidly growing low- or no-carbon technologies

A terminal assessment of stages theory : introducing a dynamic states approach to entrepreneurship

Stages of Growth models were the most frequent theoretical approach to understanding entrepreneurial business growth from 1962 to 2006; they built on the growth imperative and developmental models of that time. An analysis of the universe of such models (N=104) published in the management literature shows no consensus on basic constructs of the approach, nor is there any empirical confirmations of stages theory. However, by changing two propositions of the stages models, a new dynamic states approach is derived. The dynamic states approach has far greater explanatory power than its precursor, and is compatible with leading edge research in entrepreneurship