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Stent malapposition is one of the most significant precursors of stent thrombosis and restenosis. Adverse haemodynamics may play a key role in establishing these diseases, although numerical studies have used idealised drug transport models to show that drug transport from malapposed drug-eluting stent struts can be significant. This paper aims to study whether drug transport from malapposed struts is truly significant. Another aim is to see whether a streamlined strut profile geometry – with a 61% smaller coating but a 32% greater coating-tissue contact area – can mitigate the adverse haemodynamics associated with stent malapposition while enhancing drug uptake.

Two- and three-dimensional computational fluid dynamics simulations were used in this study. Unlike past simulations of malapposed drug-eluting stent struts, a qualitatively validated drug-transport model which simulates the non-uniform depletion of drug within the drug coating was implemented.

It was shown that even a 10-µm gap between the strut and tissue dramatically reduces drug uptake after 24 h of simulated drug transport. Furthermore, the streamlined strut profile was shown to minimise the adverse haemodynamics of malapposed and well-apposed stent struts alike and enhance drug uptake.

Unlike prior numerical studies of malapposed stent struts, which did not model the depletion of drug in the drug coating, it was found that stent malapposition yields negligible drug uptake. The proposed semicircular-profiled strut was also shown to be advantageous from a haemodynamic and drug transport perspective.

Interface distinct two-phase computational fluid dynamics (CFD) simulations require accurate tracking in surface curvature, surface area and volume fraction data to precisely calculate effects such as surface tension, interphase momentum and interphase heat and mass transfer exchanges. To attain a higher level of accuracy in two-phase flow CFD simulations, the intersection marker (ISM) method was developed. The ISM method has cell-by-cell remeshing capability that is volume conservative, maintains surface continuity and is suited for the tracking of interface deformation in transient two-phase flow simulations. Studies of isothermal single bubbles rising in quiescent water were carried out to test the ISM method for two-phase flow simulations.

The ISM method is a hybrid Lagrangian–Eulerian front tracking algorithm which can model an arbitrary three-dimensional surface within an array of cubic control volumes. Fortran95 was used to implement the ISM method, which resulted in approximately 25,000+ lines of written code and comments. To demonstrate the feasibility of the ISM algorithm for two-phase flow simulations, the ISM algorithm was coupled with an in-house CFD code, which was modified to simulate two-phase flows using a single fluid formulation. The constitutional equations incorporated terms of variable density and viscosity. In addition, body force source terms were included in the momentum equation to account for surface tension and buoyancy effects.

The performance of two-phase flow simulations was benchmarked against experimental data for four air/water bubbles with 1, 2.5, 5 and 10 mm of diameter rising in quiescent fluid. A variety of bubble sizes were tested to demonstrate the accuracy of the ISM interface tracking method. The results attained were in close agreement with experimental observations.

The results obtained show that the ISM method is a viable means for interface tracking of two-phase flow CFD simulations. Other applications of the ISM method include simulations of solid–fluid interaction and other immersed boundary flow problems.

The ISM method is a novel approach to front tracking, and the results shown are original in content.

The development of novel cooling techniques is needed in order to be able to substantially increase the performance of integrated electronic circuits whose operations are limited by the maximum allowable temperature. Air cooled micro‐channels etched in the silicon substrate have the potential to remove heat directly from the chip. For reasonable pressure drops, the flow in micro‐channels is inherently laminar, so that the heat transfer is not very large. A synthetic jet may be used to improve mixing, thereby considerably increasing heat transfer. This paper seeks to address this issue.

CFD has been used to study the flow and thermal fields in forced convection in a two‐dimensional micro‐channel with an inbuilt synthetic jet actuator. The unsteady Navier‐Stokes and energy equations are solved. The effects of variation of the frequency of the jet at a fixed pressure difference between the ends of the channel and with a fixed jet Reynolds number, have been studied with air as the working fluid. Although the velocities are very low, the compressibility of air has to be taken into account.

The use of a synthetic jet appreciably increases the rate of heat transfer. However, in the frequency range studied, whilst there are significant changes in the details of the flow, due primarily to large phase changes with frequency, there is little effect of the frequency on the overall rate heat transfer. The rates of heat transfer are not sufficiently large for air to be a useful cooling medium for the anticipated very large heat transfer rates in future generations of microchips.

The study is limited to two‐dimensional flows so that the effect of other walls is not considered.

It does not seem likely that air flowing in channels etched in the substrate of integrated circuits can be successfully used to cool future, much more powerful microchips, despite a significant increase in the heat transfer caused by synthetic jet actuators.

CFD is used to determine the thermal performance of air flowing in micro‐channels with and without synthetic jet actuators as a means of cooling microchips. It has been demonstrated that synthetic jets significantly increase the rate of heat transfer in the micro‐channel, but that changing the frequency with the same resulting jet Reynolds number does not have an effect on the overall rate of heat transfer. The significant effect of compressibility on the phase shifts and more importantly on the apparently anomalous heat transfer from the “cold” air to the “hot” wall is also demonstrated.

This research aims to identify the intentions behind becoming an entrepreneur and the perception of entrepreneurial failure among different groups of students. There has been significant research discussing the motivations behind becoming an entrepreneur. However, such a research study is often focused on individuals who are already in the entrepreneurial process. Therefore, this research focuses on the understanding of the entrepreneurial process specified on the intentions of becoming an entrepreneur and the associated risk, in the context of a learning process.

The perspectives of students towards becoming an entrepreneur and their perception of associated risk are identified. A comparative exploratory case study method is used. Three cases developed in the light of empirical evidence consist of Business, Law and Science, technology, engineering and mathematics (STEM) students.

Major results show that the law and STEM students were on the same line in terms of motivational factors, such as being career driven. In contrary, the business students were more driven by personal factors such as leaving something behind and building something meaningful.

Whilst studies have attempted to understand entrepreneurial intentions, little work has considered students and their views on becoming entrepreneurs. Even with studies that looked at this subject matter, the focus was mainly business students. The authors build on previous work and construct the authors' views based on multi-disciplinary student base to know more about their intentions to become an entrepreneur. The science and law students were more influenced by external factors, whereas business students were focused more on their personal goals. Such classification of the diverse intentions based on student discipline opens a new and promising research avenue to better develop entrepreneurial education not only for business students but across all disciplines in higher education.

The purpose of this study is to examine entrepreneurial activity in the USA and whether it supports a “pull” or a “push” theory of startup creation. The “push” theory argues that individuals are pushed into entrepreneurship by negative external forces, such as job dissatisfaction, difficulty finding employment, insufficient salary or inflexible work schedule. The “pull” theory contends that individuals are attracted into entrepreneurial activities seeking independence, self-fulfillment, wealth and other desirable outcomes.

This paper incorporates three well-established measures when looking at impact factors; unemployment rates, gross domestic product (GDP) and household income. The current study is unique in that it introduces the Kauffman Startup Activity Index (KSAI) as the measure of entrepreneurial activity when examining impact factors.

The results of this study support the “pull” theory (or the entrepreneurial effect) of startup activity and further supports the idea that entrepreneurs look for opportunities in the marketplace, rather than being “forced” into self-employment.

Research is limited to having US data at the national level. Follow-up research could include parsing the data out to the state and local levels.

The results of this study suggest to the economic development community that incentives during times of economic growth could further incent entrepreneurial activity.

The tact used by the authors is unique in that it relied upon three historical variables – unemployment rates, US GDP and household income – and introduced a new variable, the KSAI, rather than the previously relied upon national startup activity data or startup activity.

Die Entwicklungshilfe ist eine der bedeutendsten und meist diskutierten Aktionen unserer Zeit. Gewaltige Summen sind bereits dafür aufgewendet worden, noch höhere sollen zum Einsatz kommen.

The purpose of this paper is to show a thermodynamic analysis to determine the contribution of each term of the total energy balance.

The thermodynamic analysis comprises a number of numerical simulations where some terms, typically ignored by the commonly used approximations, are removed from the total energy equation to quantify the effects in the flow and heat transfer fields. The case study is the differentially heated square cavity flow, in which the effects of work done by the pressure forces contribute significantly to the energy balance. Because local magnitudes are computed here for discussion, the dimensional form of the governing equations is preferred and a numerical model without any restrictive approximation about the role of the pressure is used.

The results show that the work of gravity forces term is in perfect balance with the work of pressure forces term, and thus, ignoring the contribution of one of them yields an incorrect solution. In addition, it is shown that the assumption of zero divergence of the Boussinesq approximation can be erroneous, even for a natural convection flow case where the temperature difference is very small.

As the flow and heat transfer governing equations are complex, simplifying assumptions are generally used; that is, the Boussinesq and low Mach number approximations. These assumptions are systematically adopted without any validation process and without considering that they modify the physical meaning of one or more of the thermodynamic quantities, particularly the pressure. This fact results in inconsistencies of the different forms of energy.

This is the first time that the terms of the total energy balance are quantified in such a way, in a differentially heated square cavity flow, which is a case study addressed by several authors.

A finite element solution on the interaction of surface radiation and variable property laminar natural convection is presented. Finite element formulation of the governing equations, associated with variable property natural convection, and incorporation of the radiative boundary conditions has been extensively discussed. The study also aims to highlight the limiting value of the terminal temperature difference (TTD), below which the natural convection heat transfer becomes the sole heat transfer mode, i.e. the effect of surface radiation can be neglected. The effects of variations of emissivity and TTD are also presented.

The purpose of this paper is to classify the source countries of inward foreign direct investments (FDIs) to Turkey and to Germany as individual samples of developing and developed economies, to produce practical information to target company managers and owners that they can use for having much more investments or getting more bargaining power with the existing or potential investors.

Cluster analysis methodology with Ward’s (1963) technique is used to create significant groups out of FDI source countries.

The results show that foreign direct investors – labeled by their country of origin – investing in Turkey are grouped into two main clusters. First main cluster of Turkey has three sub-clusters. Investors investing in Germany are also grouped into two main clusters. First main cluster of Germany has two sub-clusters. Of all seven clustering criteria, four of them were prominent in grouping, which are: having a high equity ownership in the investment, investing in companies with high market capitalization, investing in companies with high/low financial risk and high/low financial performance, and investing in young companies. Furthermore, investors from same origin behave differently in Turkey and Germany. They adjust their attitude toward risk when the host country changes. Lastly, source countries in the sample that have a minimum distance in between, are the ones sharing similar cultural values.

The limitations of the study are the small number of observation with complete and standard company data needed, especially in Turkey, and the compelled shortness of time period for the empirical analysis. Some suggestions were offered for future researches to contribute to the topic by using bigger samples; by making variations in country, time, or industry; by relating country factors to social/entrepreneurial factors; and by supporting the research with qualitative techniques.

This paper constitutes a contribution to the empirical field research in Turkey, an emerging country with very limited firm-level financial and ownership data, compared to Germany, a developed country with relatively more data availability.

The purpose of this study was to develop pre-exposure prophylaxis (PrEP) education materials that directly address the needs of trans women. PrEP medication is an effective HIV prevention strategy, but some groups at high risk of HIV, such as transgender (trans) women, have suboptimal uptake and adherence. Most PrEP marketing has been aimed fat men who have sex with men (MSM) and include trans women as part of that audience, but this strategy ignores important differences in perceptions of and barriers to PrEP.

This study used a social marketing approach grounded in exchange theory to systematically develop and pretest PrEP messaging and communication materials for trans women through qualitative (focus groups: n = 5, 34 participants) and quantitative (surveys: n = 128) methods in Philadelphia and the San Francisco Bay area. Segmentation analysis, perceptual mapping and vector message modeling techniques were used to create three-dimensional visualizations of PrEP perceptions to identify highly targeted messaging. Working with trans artists, the authors developed prototype materials using the targeted messaging and pretested these (n = 11) in both locations for feedback on content, look and insight on appropriate intervention strategies.

Using segmentation and perceptual mapping, this study identified key PrEP messaging across different subgroups, including by demographic and psychographic variables. Differences by group were determined to not be significant and overall messages that would resonate with all groups were built into the materials. Pretesting sessions indicated high acceptability of the messaging and trans women-centered approach to increase PrEP uptake.

To the best of the authors’ knowledge, this is the first study to use a social marketing framework to create targeted PrEP communication materials for trans women in partnership with trans women.