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This article reviews the literature on Christmas economics. First, we present an overall picture of the debate on the potential welfare loss of gift-giving and we show strategies that reduce the potential welfare loss and might increase the number of presents received. Second, we discuss the effect of Christmas on prices and the business cycle. We provide evidence that at Christmas stock prices and airfares increase, while food prices decrease.
Different sensor types using chemical and biochemical principles are described. The former are mainly gas sensors, the latter are applied especially to liquids. Those label-free direct detection methods are compared with applications where assays take advantage of labeled receptors.
Furthermore, selected applications in the area of gas sensors are discussed, and sensors for process control, point-of-care diagnostics, environmental analytics, and food analytics are reviewed. In addition, multiplexing approaches used in microplates and microarrays are described.
On account of the huge number of sensor types and the wide range of possible applications, only the most important ones are selected here.
Management and cost accounting has been the basic toolbox in business administration for decades. Today it is an integral part of all curricula in business education and no student can afford not to be familiar with its basic concepts and instruments. At the same time, business in general, and management accounting in particular, is becoming more and more international. English clearly has evolved as the „lingua franca“ of international business. Academics, students as well as practitioners exchange their views and ideas, discuss concepts and communicate with each other in English. This is certainly also true for cost accounting and management accounting.
The composition of vascularized adipose tissue is still an ongoing challenge as no culture medium is available to supply adipocytes and endothelial cells appropriately. Endothelial cell medium is typically supplemented with epidermal growth factor (EGF) as well as hydrocortisone (HC). The effect of EGF on adipocytes is discussed controversially. Some studies say it inhibits adipocyte differentiation while others reported of improved adipocyte lipogenesis. HC is known to have lipolytic activities, which might result in mature adipocyte dedifferentiation. In this study, we evaluated the influence of EGF and HC on the co-culture of endothelial cells and mature adipocytes regarding their cell morphology and functionality. We showed in mono-culture that high levels of HC promoted dedifferentiation and proliferation of mature adipocytes, whereas EGF seemed to have no negative influence. Endothelial cells kept their typical cobblestone morphology and showed a proliferation rate comparable to the control independent of EGF and HC concentration. In co-culture, HC promoted dedifferentiation of mature adipocytes, which was shown by a higher glycerol release. EGF had no negative impact on adipocyte morphology. No negative impact on endothelial cell morphology and functionality could be seen with reduced EGF and HC supplementation in co-culture with mature adipocytes. Taken together, our results demonstrate that reduced levels of HC are needed for co-culturing mature adipocytes and endothelial cells. In co-culture, EGF had no influence on mature adipocytes. Therefore, for the composition of vascularized adipose tissue constructs, the media with low levels of HC and high or low levels of EGF can be used.
In this article, liposome-based coatings aiming to control drug release from therapeutic soft contact lenses (SCLs) materials are analyzed. A PHEMA based hydrogel material loaded with levofloxacin is used as model system for this research. The coatings are formed by polyelectrolyte layers containing liposomes of 1,2-dimyristoyl-sn-glycero-3- phosphocholine (DMPC) and DMPC1cholesterol (DMPC1 CHOL). The effect of friction and temperature on the drug release is investigated. The aim of the friction tests is to simulate the blinking of the eyelid in order to verify if the SCLs materials coated with liposomes are able to keep their properties, in particular the drug release ability. It was observed that under the study conditions, friction did not affect significantly the drug release from the liposome coated PHEMA material. In contrast, increasing the temperature of release leads to an increase of the drug diffusion rate through the hydrogel. This phenomenon is recorded both in the control and in the coated samples.
In this study, a novel strategy has been developed for the assembly of polyelectrolyte multilayer (PEM) on CaCO3 templates in acidic pH solutions, where consecutive polyelectrolyte layers (heparin/poly(allylamine hydrochloride) or heparin/chitosan) were deposited on PEM hollow microcapsules established previously on CaCO3 templates. The PEM build-up, hollow capsule characterization and successful encapsulation of fluorescein 5(6)-isothiocyanate (FITC)-Dextran by coprecipitation with CaCO3 are demonstrated. Improvement by the removal of CaCO3 core was achieved while the depositions. In the course of the release profile, high retardation for encapsulated FITC-Dextran was observed. The combined shell capsules system is a significant trait that has potential use in tailoring functional layer-by-layer capsules as intelligent drug delivery vehicles where the preliminary in vitro tests showed the responsiveness on the enzymes.
It is assumed that more education leads to better understanding of complex systems. Some researchers, however, find indications that simple mechanisms like stocks and flows are not well understood even by people who have passed higher education. In this paper, we test people’s understanding of complex systems with the widely studied stock-and-flow (SF) tasks. SF tasks assess people’s understanding of the interplay between stocks and flows. We investigate SF failure of domain experts and novices in different knowledge domains. In particular, we compare performance on the original study’s bathtub task with the square wave pattern with two alternative cover stories from the engineering and business domains on different groups of business and engineering students from different semesters. Further, we show that, while engineering students perform better than business students, with progressing in higher education, students may lose the capability of dealing with simple SF tasks. We thus find hints on déformation professionelle in higher education.
The conventional view of the value-creation chain suggests offering high-value propositions at the product level (in terms of benefits provided by elements of the product) to attain high-value perceptions at the customer level, which should ultimately result in high-value appropriation at the firm level (i.e. relationship, volume, pricing and financial success). This study challenges this view and provides a differentiated understanding of the value creation chain. With a multi-industry sample of 339 companies and a sample of 626 customers to validate managerial assessments, the authors apply a configurational approach to identify whether and to what extent offering high-value propositions at the product level is necessary or sufficient for achieving superior value perceptions at the customer level and high-value appropriation at the firm level. Taking into account the company-internal and company-external environment of the value-creation chain, the study identifies seven value creation chain constellations.
In retail environments, consumers commonly evaluate products while standing on some type of flooring and concurrently being exposed to music; however, no study has examined the interaction of these two atmospheric cues. To bridge this gap, this research examines whether retailers can benefit from creating multisensory atmospheric congruent rather than incongruent retail environments of flooring and music. The results of an experiment in a real retail store reveal positive effects of multisensory congruent retail environments (e.g., soft music combined with soft flooring) on product evaluations. This study provides a new process explanation with consumers’ purchase-related self-confidence mediating these effects. Specifically, consumers in congruent rather than incongruent retail environments experience more purchase-related self confidence, which in turn leads to more favorable product evaluations. Furthermore, this study shows that consumers with a low rather than a high preference for haptic information are influenced more by multisensory atmospheric congruence when evaluating a product haptically.
Small Island Developing States (SIDS) face tension between economic growth and environmental impact. Tourism fuels growth, but the resulting solid waste and other pollutants threaten the SIDS’ natural beauty, quality of life for residents, attractiveness to tourists, and economic success. We assess the tension between tourism-driven economic growth and environmental degradation from a limits-to-growth perspective, developing a generic system dynamics model of the problem using 38 years of data from the Maldives to estimate parameters and Monte-Carlo methods to assess the sensitivity of results to uncertainty. We contrast development paths for the next three decades under three sets of policies focusing on promoting growth, managing tourism demand–supply balance, and improving waste management. Findings are counterintuitive; policies focused on better waste management alone are self defeating, because they increase tourism, growth and waste generation, undermining attractiveness and growth later. Policies that limit tourism demand improve economic and environmental health.
Relocation of production to countries with low labour costs has induced increased labour market flexibility, which has been praised as a silver bullet for economic growth and low unemployment. Within a unionised oligopoly framework, in which a multinational firm has the option to relocate its production to a foreign country, we analyse the welfare implications of both centralised and flexible wage-setting regimes. For very low foreign wages, wage flexibility leads to higher welfare than a rigid centralised regime. In contrast, for ‘intermediate’ wage levels in the foreign country, an industry-wide uniform wage leads to higher social welfare than flexible wages.
The coculture of osteogenic and angiogenic cells and the resulting paracrine signaling via soluble factors are supposed to be crucial for successfully engineering vascularized bone tissue equivalents. In this study, a coculture system combining primary human adiposederived stem cells (hASCs) and primary human dermal microvascular endothelial cells (HDMECs) within two types of hydrogels based on methacryloyl‐modified gelatin (GM) as three‐dimensional scaffolds was examined for its support of tissue specific cell functions. HDMECs, together with hASCs as supporting cells, were encapsulated in soft GM gels and were indirectly cocultured with hASCs encapsulated in stiffer GM hydrogels additionally containing methacrylate‐modified hyaluronic acid and hydroxyapatite particles. After 14 days, the hASC in the stiffer gels (constituting the “bone gels”) expressed matrix proteins like collagen type I and fibronectin, as well as bone‐specific proteins osteopontin and alkaline phosphatase. After 14 days of coculture with HDMEC‐laden hydrogels, the viscoelastic properties of the bone gels were significantly higher compared with the gels in monoculture. Within the soft vascularization gels, the formed capillary‐like networks were significantly longer after 14 days of coculture than the structures in the control gels. In addition, the stability as well as the complexity of the vascular networks was significantly increased by coculture. We discussed and concluded that osteogenic and angiogenic signals from the culture media as well as from cocultured cell types, and tissue‐specific hydrogel composition all contribute to stimulate the interplay between osteogenesis and angiogenesis in vitro and are a basis for engineering vascularized bone.
Theory predicts that market‐timing activities bias Jensen's alpha (JA). However, empirical studies have failed to find consistent evidence of this bias. We tackle this puzzle in a nested model analysis and show that the bias contains an exogenous market component that is unrelated to market‐timing skill. In a comprehensive empirical analysis of US mutual funds, we find that the timing‐induced bias in JA is mainly driven by this market component, which is uncorrelated with measured timing activities. Measures of total performance that allow for timing activities are virtually identical to JA, even if timing activities are present in the evaluated fund. Hence, we conclude that JA is a sufficient measure of total performance.
Contemporary public enterprises differ from their forebears. Today, they are more similar to private enterprises, receiving far more attention than previously, when privatization processes all over the world were in the spotlight. Furthermore, the broad research stream of entrepreneurship has so far neglected the consideration of public enterprises. To set a future research agenda, the author examines the dispersed literature using an integrative and organizing framework to identify major topics and research findings. This paper reviews articles that investigate the entrepreneurship in contemporary public enterprises. Despite the growing scholarly interest globally, this systematic literature review indicates there is no more than a loose connection between the literature streams of public entrepreneurship and corporate entrepreneurship. Specifically, the review shows that the multidimensional concept of entrepreneurial orientation has thus far been ignored, although autonomy plays a significant role in the literature review, namely in the context of the interference of the public owner. It also reveals other essential research gaps, such as the development of a modern theory of public enterprises. The linked research stream of public-sector corporate entrepreneurship offers a broad area of scholarly research and should encourage further investigation.
Artificial adipose tissue (AT) constructs are urgently needed to treat severe wounds, to replace removed tissue, or for the use as in vitro model to screen for potential drugs or study metabolic pathways. The clinical translation of products is mostly prevented by the absence of a vascular component that would allow a sustainable maintenance and an extension of the construct to a relevant size. With this study, we aimed to evaluate the suitability of a novel material based on bacterial cellulose (CBM) on the defined adipogenic differentiation of human adipose-derived stem cells (ASCs) and the maintenance of the received adipocytes (diffASCs) and human microvascular endothelial cells (mvECs) in mono- and coculture. A slight acceleration of adipogenic differentiation over regular tissue culture polystyrene (TCPS) was seen on CBM under defined conditions, whereas on the maintenance of the generated adipocytes, comparable effects were detected for both materials. CBM facilitated the formation of vascular like structures in monoculture of mvECs, which was not observed on TCPS. By contrast, vascular-like structures were detected in CBM and TCPS in coculture by the presence of diffASCs. Concluding, CBM represents a promising material in vascularized AT engineering with the potential to speed up and simplify the in vitro setup of engineered products.
We report on the reflectance, transmittance and fluorescence spectra (λ=200–1200nm) of four types of chicken eggshells (white, brown, light green, dark green) measured in situ without pretreatment and after ablation of 20–100 μm of the outer shell regions. The color pigment protoporphyrin IX (PPIX) is embedded in the protein phase of all four shell types as highly fluorescent monomers, in the white and light green shells additionally as non-fluorescent dimers, and in the brown and dark green shells mainly as non-fluorescent poly-aggregates. The green shell colors are formed from an approximately equimolar mixture of PPIX and biliverdin. The axial distribution of protein and color pigments were evaluated from the combined reflectances of both the outer and inner shell surfaces, as well as from the transmittances. For the data generation we used the radiative transfer model in the random walk and Kubelka-Munk approaches.
Melamine–formaldehyde (MF) resins are widely used as adhesives and finishing materials in the wood industry. During resin cure, either methylene ether or methylene bridges are formed, leading to the formation of a three‐dimensional resin network. Not only the curing degree, but also the chemical species present in the cured resin determine the quality of the final product. Analytical methods allowing a detailed investigation of network formation are of great benefit to manufacturers. In the present work, resin cure of an MF precondensate is studied at different temperatures (100–200 °C) without considering the initial pH as a factor. Isoconversional kinetic analysis based on exothermal curing enthalpies enables calculation of the crosslinking degree at a given time/temperature regime. A semiquantitative determination of the chemical groups present is performed based on solid‐state nuclear magnetic resonance data. Fourier transform infrared spectroscopy has shown to be a fast and reliable analytical tool with high sensitivity toward functional groups and with great potential for at‐line process control.
A new two-dimensional fluorescence sensor system was developed for in-line monitoring of mammalian cell cultures. Fluorescence spectroscopy allows for the detection and quantification of naturally occurring intra- and extracellular fluorophores in the cell broth. The fluorescence signals correlate the the cells' current redox state and other relevant process parameters. Cell culture pretests with twelve different excitation wavelengths showed that only three wavelengths account for a vast majority of spectral variation. Accordingly, the newly developed device utilizes three high-power LEDs as excitation sources in combination with a back-thinned CCD-spectrometer for fluorescence detection.