1,971 research outputs found

    An overview of franchising in the hospitality industry of Turkey

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    Tourism is regarded as one of the fastest growing industries of our time. International hotel chains seem to contribute this development to a great amount. These hotels invest in Turkey since 1950s. Recently, these investments seem to be made majorly as franchises. Today, franchising seems to be one of the major strategies to enter global markets. And the system is popular because of its organisational and financial advantages. Although Franchising is adopted and frequently used in tourism industry, there are not (if any) any studies investigating facts and figures of the subject. In this regard, herein it is aimed to overview the current state of franchising in the Turkish tourism industry. Therefore, international hotel chains operating through Franchising in the hospitality industry of Turkey are reviewed in this study. Findings of the study suggest that international hotel chains aiming to expand in the market of Turkey prefer franchising as the major growth strategy to any other

    Statistical Methodological Issues in Studies of Air Pollution and Respiratory Disease.

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    Epidemiological studies have consistently shown short term associations between levels of air pollution and respiratory disease in countries of diverse populations, geographical locations and varying levels of air pollution and climate. The aims of this paper are: (1) to assess the sensitivity of the observed pollution effects to model specification, with particular emphasis on the inclusion of seasonally adjusted covariates; and (2) to study the effect of air pollution on respiratory disease in Melbourne, Australia.Air pollution; Autocorrelation; Generalized additive models; Seasonal adjustment; Respiratory disease

    Detachment of semiflexible polymer chains from a substrate - a Molecular Dynamics investigation

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    Using Molecular Dynamics simulations, we study the force-induced detachment of a coarse-grained model polymer chain from an adhesive substrate. One of the chain ends is thereby pulled at constant speed off the attractive substrate and the resulting saw-tooth profile of the measured mean force vs height $D$ of the end-segment over the plane is analyzed for a broad variety of parameters. It is shown that the observed characteristic oscillations in the $< f >$-$D$ profile depend on the bending and not on the torsional stiffness of the detached chains. Allowing for the presence of hydrodynamic interactions (HI) in a setup with explicit solvent and DPD-thermostat, rather than the case of Langevin thermostat, one finds that HI have little effect on the -DD profile. Also the change of substrate affinity with respect to the solvent from solvophilic to solvophobic is found to play negligible role in the desorption process. In contrast, a changing ratio ĻµsA/ĻµsB\epsilon_s^A / \epsilon_s^B of the binding energies of AA- and BB-segments in the detachment of an ABAB-copolymer from adhesive surface strongly changes the -DD profile whereby the BB-spikes vanish when ĻµsA/ĻµsB<0.15\epsilon_s^A / \epsilon_s^B < 0.15. Eventually, performing an atomistic simulation of a (bio)-polymer {\it polyglycine}, we demonstrate that the simulation results, derived from our coarse-grained model, comply favorably with those from the all-atom simulation.Comment: Latex, 12 pages, 8 figures, to appear in JC

    Forecasting age-related changes in breast cancer mortality among white and black US women: A functional approach

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    The disparity in breast cancer mortality rates among white and black US women is widening with higher mortality rates among black women. We apply functional time series models on age-specific breast cancer mortality rates for each group of women, and forecast their mortality curves using exponential smoothing state-space models with damping. The data were obtained from the Surveillance, Epidemiology and End Results (SEER) program of the US (SEER, 2007). Mortality data were obtained from the National Centre for Health Statistics (NCHS) available on the SEER*Stat database. We use annual unadjusted breast cancer mortality rates from 1969 to 2004 in 5-year age groups (45-49, 50-54, 55-59, 60-64, 65-69, 70-74, 75-79, 80-84). Age-specific mortality curves were obtained using nonparametric smoothing methods. The curves are then decomposed using functional principal components and we fit functional time series models with four basis functions for each population separately. The curves from each population are forecast and prediction intervals are calculated. Twenty-year forecasts indicate an over-all decline in future breast cancer mortality rates for both groups of women. This decline is steeper among white women aged 55-73 and black women aged 60-84. For black women under 55 years of age, the forecast rates are relatively stable indicating no significant change in future breast cancer mortality rates among young black women in the next 20 years.Breast cancer mortality, racial and ethnic disparities, screening, trends, forecasting, functional data analysis

    The Relationships Between Thinking Styles, Servant Leadership and Extra-role Service Behaviour: An Empirical Study in the Hotel Industry

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    Drawing from thinking styles theories and servant leadership theories, this study investigates whether thinking styles are the predictors of extra-role service behaviour and which of them mediates the effects of servant leadership on extra-role service behaviours. Data collected from frontline hotel employees in Cappadocia were employed to reveal these relationships. The results from regression analysis and path model propose that employees with certain thinking styles display extra-role service performance and the presence of servant leadership fosters employeesā€™ extra-role service behaviours through thinking styles. In brief, there is support for the fully mediated model that servant leadership enhance extra-role service behaviours through type three thinking styles. Importance of thinking styles to the decision makers in the hotel industry and future researchers are debated. Keywords: Hotel industry, Thinking styles, Servant leadership, Extra-rol

    Validation of remotely-sensed soil moisture observations for bare soil at 1.4 GHz:A quantitative approach through radiative transfer models to characterize abrupt transitions caused by a ponding event in an agricultural field,modifications to radiative transfer models,and a mobile groundbased system

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    Soil moisture controls the physical processes that exchange mass and energy between the atmosphere and the land surface in the hydrologic cycle. Improved observations of soil moisture may lead to dramatic improvements in weather forecasting, seasonal climate prediction, and our understanding of the physical, chemical and biological processes that occur within the soil. Recent advances in remote sensing have shown that microwave radiometry is a suitable approach to retrieve soil moisture. However, the quantitative aspects of remotely-sensed soil moisture observations are not well-known, and validation of remotely-sensed measurements is an important challenge. In this dissertation, we describe efforts made at Iowa State University to establish the framework needed for the validation of remotely-sensed soil moisture observations. In the process of developing this framework, we engineered new tools that can be used by both our research group and the wider remote sensing community, and we discovered new science. The first tool is a direct-sampling digital L-band radiometer system. This radiometer system is the world\u27s first truly mobile ground-based system. The other tools are radiative transfer models that have been modified in order to be applied to the most general remote sensing situations. An incoherent radiative transfer model was modified to include the contributions of a semi-infinite layer, and a coherent radiative transfer model was modified to account for abrupt transitions in the electrical properties of a medium. The models were verified against each other and the code was written in a user-friendly format. We demonstrated the use of these tools in determining the effect of the transient ponding of water in an agricultural field on the remote sensing signal. We found that ponding was responsible for a 40 K change in the L-band horizontally-polarized brightness temperature. We were able to model this change with both modified coherent and incoherent radiative transfer models. Finally we gave an example of how these tools could be used to quantitatively compare remote sensing observations with models

    Micron-Level Actuator for Thermal-Fluid Control in Microchannels

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    Effectiveness of an actuator is investigated for thermal-flow control in microchannels. First, simulations of a single actuator in a quiescent external medium are performed in order to study the parameters characterizing the synthetic jet flow from the actuator. For this purpose, a simplified, two-dimensional configuration is considered. The membrane motion is modeled in a realistic manner as a moving boundary in order to accurately compute the flow inside the actuator cavity. The geometric and actuation parameters of the actuator are investigated to define the effectiveness of the jet flow. The study is done initially at macro scales. Then, the flow in the Knudsen number range of less than 0.1 is modeled starting with a conventional compressible Navier-Stokes solver valid for continuum approach. Its boundary conditions, however, are modified to account for the slip velocity and the temperature jump boundary conditions encountered in micron-level devices. Compressibility effects are also taken into account and modeled through the compressible flow solver. The utility of synthetic jet actuators for manipulating fluid flows has been shown for mostly macro- and mini-scale applications. To the best of the author\u27s knowledge, there have been only a few studies on micro-sized synthetic jets; also they have only been modeled assuming continuum flow regime with no-slip at the walls. Therefore, several issues must still be addressed for micron-scale synthetic jets and also their applications to micron-level problems. Thus, as the second part of the study, a micron-level synthetic jet is proposed as a flow control device to manipulate the separated flow past a backward facing step in a microchannel. First, an uncontrolled flow past a backward facing step in a channel is computed. Then, a synthetic jet actuator is placed downstream of the step where the separation occurs. A large number of test cases have been analyzed. It is observed that the size of the separation bubble and its enstrophy are functions of the geometry of the actuator cavity and the membrane oscillation parameters. Considerable reduction in separation bubble size as well as in enstrophy is achieved using the actuator. Finally, a design for thermal management of a semiconductor device using the present actuator is introduced. For this purpose, a single microchip dissipating heat is placed in a two dimensional rectangular channel. Then, the different cavity and actuation parameters are considered in order to infer some characteristics of the effect of controlled synthetic jet thermal management. Using the actuator, a circulation region is generated on the top surface of the microelectronic chip. It is found that the fluctuating jet interacts with the channel flow and increases the convection rate by transferring linear momentum to the channel flow. It is seen from the results of the computations that the synthetic jets can be utilized effectively to control separation in internal flow applications and that they guarantee an efficient thermal management of microelectronic devices. Therefore, the synthetic jet actuator proves itself to be an effective device for thermal-fluid control applications where low-speed flows are encountered

    Development and software implementation of modelling tools for rapid fermentation process development using a parallel mini-bioreactor system

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    In order to establish a generic framework for the rapid development and optimisation of scalable fermentation processes, a novel methodology for simplifying model building was explored. This approach integrates small-scale fermentations with model-based experimental design (DoE) and predictive control strategies. In this study, four 1.4 litre vessels were characterised for power input, volumetric oxygen transfer coefficient (KLa) and mixing, to assess its potential for replicating cell culture rapidly. Engineering characterisation results showed excellent propeller operation over a range of 400-1200 rpm and up to the maximum motor output and under various air flow rates in fluid densities up to 4.21 Cp/mPa s (1.211 g/cm3 ). Limits were reached using glycerol (99%) at fluid viscosities of 500Cp/mPa s (1.253g/cm3 ) at 800 rpm and no air flow, hence experiencing the most resistance. This was the most taxing condition in terms of energy input into the system. Furthermore, we determined the efficient gas dispersion which is considered important for oxygen bubble dispersion in viscous fluids. The potential gas dispersion could be calculated as a function of both impeller speed, airflow rate, and the fluid viscosity. The calculations provided a working impeller speed of >263 rpm for >0.5 vvm air flow rate as preliminary parameters in our advanced modelling section. The key outcome of the KLa study was that the results showed suitable potential for mass transfer for high cell density fermentations, for each of the parallel stirred tank bioreactors. To assess the usability of the parallel bioreactors be used for bioprocess rapid development purposes Escherichia coli W3110 was characterised in the 1L WV vessels. So overall the experiments included testing the performance of the vessels engineering parameters and also the biological fermentations confirming that the system was suitable for parallel operation with high reproducibility. For model building, especially suited for the 4-reactor set up the parallel bioreactors a fractional factorial design was used, in which models could be rapidly built and implemented for further research. The screening and model optimisation helped to reduce the development time by using the parallel equipment. Batches of four reactors could be completed in parallel in which comparable experimental results were obtained rapidly for new fermentation models. Optical density measurements provided a quick off-line analysis of the growth curve of microbial populations, as compared to cell plate counts or dry weights that require more time. For the model development and the establishment of our integrated software modelling tool, a modified logistic model was developed to predict microbial growth kinetics. First-order kinetic models, logistic, and Gompertz models were used and comparatively analysed to assess the model fit to test batch data. The logistic model was favourable for mapping and simulating the later phases of bacterial growth, while the well-established exponential growth model predicted the early lag phase in our stoichiometric growth simulation software tool better. The initialisation of the previous fermentation model allowed us to build a statistical model, which was based on the engineering characteristics for optimisation of biomass. Therefore, batch nutrient supply with the aid of stoichiometric models could be tested and modelled. DoE model data was improved with metabolic flux analysis to develop an advanced feeding strategy by testing various metabolic pathways and the nutrients used in experimentation. Bacterial growth predictions and media optimisation were tested for maximising microbial biomass yields. We then modelled the dissolved oxygen concentration and substrate utilisation. The techniques and principles of dynamic flux balance analysis, mechanistic modelling, and stoichiometric mass balancing were used. The aim was to create and validate our integrated software based on advanced modelling for the parallel bioreactor systems and tested through application for E. coli fermentations. Optimising microbial biomass was the main target in this project, with the data collected from fermentation being the strongest comparator and validator. A new software for the integration of DoE and Dynamic flux balance analysis (DFBA) techniques with the intention of creating a working fermentation platform for the Multifors equipment via simulation and fermentation optimisation was the novel outcome of this research. The tool could provide functions for speeding up development time and control of parallel bioreactors
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