5916 research outputs found
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Legitimacy in the eyes of the beholders: Public expectations from aviation organizations during earthquakes
No full textThis study examines public legitimacy judgments toward airlines and aviation authorities during the most severe earthquakes in T & uuml;rkiye by analyzing social media posts. The research explores public expectations and reactions during disasters using content analysis of posts tagging these organizations. The study shows that the public expects aviation organizations to go beyond their traditional air transportation services, highlighting a heightened demand for their role in corporate social responsibility. The study contributes to the legitimacy literature by demonstrating that legitimacy is divided into two judgments -perceived appropriate or inappropriate- and that this situation changes rapidly as expectations beyond traditional service are formed during disasters. By analyz-ing real-time data shared during the disaster, this research provides critical insights for aviation organizations to address societal needs in future crises proactively. Moreover, it highlights the essential role of transportation in ensuring public welfare and calls on scholars to further explore this critical intersection of corporate social respon-sibility, legitimacy, and disaster response, urging more proactive engagement with these urgent societal challenges.Publisher versio
Improving exoskeleton brace design: Alleviating misalignment and parasitic forces
No full textThis article presents a design methodology for exoskeleton-user connection attachments, i.e., braces that aim to reduce parasitic forces and potentially improve user comfort. The proposed brace structure incorporates additional passive joints, identified through a hyperstaticity analysis to minimize undesired tangential forces, e.g., rubbing against the user's skin. To assess the proposed structure, we primarily conducted simulation experiments using a human-exoskeleton coupled model in an MSC ADAMS environment. Subsequently, a series of real-life experiments was conducted using a self-balancing bipedal exoskeleton with two distinct dummy manikins. The results demonstrated the feasibility of the proposed brace structure in reducing the parasitic forces and slippage compared to the conventional fixation approach.TÜBİTA
Health risk behaviors of adolescents in europe: a latent profile analysis of health behavior in school-aged children survey data from 43 countries
No full textPurpose: Current literature on prevention and intervention programs for European adolescents who engage in health risk behaviors is limited. Few studies have utilized latent profile analysis methods and internationally comparative data on adolescents and their health risk behaviors, highlighting the need for more comprehensive research using internationally comparative data. The current study aimed to examine the health risk behavior profiles and identify subgroups of adolescents with similar patterns of health risk behaviors using a representative sample of European countries. Findings will inform better targeted prevention strategies for this population. Methods: The study used a quantitative approach and implemented secondary data analysis using the Health Behavior in School-Aged Children survey 2017/2018 from 43 European countries to understand the prevalence of health risk behaviors among European adolescents and yield latent Results: Five latent profiles of health risk behaviors were identified for boys and six for girls. For lifestyle, and moderate substance use (3% and 0.9%) were common profiles. A moderate lifestyle risk behaviors. The findings suggest the need for better targeted prevention programming. and data mining, AI training, and similar technologies
Time-dependent optothermal performance analysis of a flexible RGB-W LED light engine
No full textThe wide application of light emitting diodes (LEDs) in lighting systems has necessitated the inclusion of spectral tunability by using multi-color LED chips. Since the lighting requirement depends on the specific application, it is very important to have flexibility in terms of the driving conditions. While many applications use single or rather white color, some recent applications require multi-spectral lighting systems especially for agricultural or human-medical treatment applications. These systems are underexplored and pose specific challenges. In this paper, a mixture of red, green, blue, white (RGB-W) LED chips was used to develop a compact light engine specifically for agricultural applications. A computational study was performed to understand the optical distribution. Later, attention was turned into development of prototype light engines followed by experimental validation for both the thermal and optical characteristics. Each LED string was driven separately at different current levels enabling an option for obtaining an infinite number of colors for numerous applications. Each LED string on the developed light engine was driven at 300 mA, 500 mA, 700 mA, and 900 mA current levels, and the optical and thermal parameters were recorded simultaneously. A set of computational models and an experimental study were performed to understand the optical and thermal characteristics simultaneously.Samuel Ginn College of Engineering, Auburn UniversityPublisher versio
Product and price competition with selection of unique and common features and different quality levels
No full textFirms must determine the best features and prices for their new products to be competitive in the market. We consider product features that are discrete and can have different quality levels. We formulate and solve the two competing firms' new product introduction and pricing problems, in which both firms introduce their products sequentially. We differentiate unique features that are present only in one product and common features that are shared between two products. The firms' new product introduction problem is formulated a mixed-integer nonlinear program, and the firms' pricing problem is formulated as a nonlinear program. These formulations allow a firm to determine the optimal features and the price in a competitive setting with general product value and cost functions. For linear product value and cost functions and a demand function linear price but nonlinear in the number of features or the feature quality level selected, we analytically determine the firms' optimal feature and quality level selection in anticipation of the features and the quality levels of the competitor's product and the resulting equilibrium prices. The optimal selection of unique features depends only on the value and cost of that feature's quality levels and the firms' price sensitivities. A firm with competitive advantage tends to include more features or high-quality feature levels in its products; otherwise, it differentiates its product via feature selection to lessen the substitution effects of common features. We identify cases where, despite the firms being symmetric other than their entry order, the leader's optimal feature selection is introducing a product with fewer or lower quality features compared to the second firm. Despite this, the leader still obtains a higher profit than the second firm.ECSEL Joint Undertaking ; TÜBİTAKPublisher versio
Getting into top-ranked management journals from business schools at the periphery: The role of doctoral education and co-authorship
No full textDrawing upon recent extensions of the centre-periphery model, we examine research and publications by academics at the periphery within the present environment of increasing institutional pressures to publish internationally. Reviewing the emergence and the historical development of management as a discipline, we describe the fragmentation in approaches to research that has arisen in this field among countries that are typically considered as the 'centre' of worldwide scholarship. We propose and empirically demonstrate that the differentiation within the 'centre' becomes largely mirrored at the periphery with respect to attention to societal contexts, research methodology and publishing. Our companion argument that doctoral education in and/or co-authorship ties to various parts of the 'centre', or a lack thereof, serve as the main vehicles in generating heterogeneity and some degree of agency at the periphery receives strong support. We also find that when ties to the 'centre' are absent contributions from the periphery remain limited. In addition, we show that tendencies towards decontextualized research, quantitative methodologies and publishing in US-based journals have become stronger over time. The article concludes with a discussion of the theoretical contributions, main findings and the implications of our study for the possible futures of research at the periphery
Dividend policies and managerial ability beyond financial constraints: insights from China
No full textManagerial ability plays a key role in the development and performance of a business and, implicitly, in corporate financing decisions and dividend opportunities. This study builds on the contradictory literature arguments related to dividend policies and analyses the influence of managerial ability and financial constraints on cash dividends, considering a comprehensive perspective of dividends expressed as both accounting and market measures of payout, yield, and growth in the context of the Chinese financial market. Alternative empirical estimations on a sample of 18,011 firm-year data of Chinese A-share listed companies between 2010 and 2019 indicate that managerial ability has a positive influence over cash dividend distribution, enhancing shareholders' returns and the attractiveness of the companies on the financial market. The effect of managerial ability is challenged by the financial constraints' conditions and state ownership. These results contribute to corporate and regulatory dividend policies, illustrating the importance of understanding the role of managerial influence on dividend decisions.Publisher versio
Housing market convergence: Evidence from germany
No full textThis paper analyses the convergence patterns of German housing prices and rents, employing a new dataset covering the country's administrative districts. In addition to conventional tests for beta-convergence and sigma-convergence, we apply Phillips and Sul's (2007) approach to allow for heterogeneous transition dynamics across districts, potentially leading to different 'convergence clubs'. Our results reveal no evidence of convergence across Germany or within states; instead, we discover widespread evidence of divergence and inter-state convergence, as well as support for the existence of convergence clubs. The results of an ordered logit model suggest that differences in the variation of GDP per capita, population density, unemployment rate, and shares of immigrants and asylum seekers have played a significant role in determining club membership from 2004 to 2020
Portfolio of colloidally stable gold-gold sulfide nanoparticles and their use in broad-band photoacoustic imaging
No full textThere is an increasing interest in non-invasive photoacoustic imaging and hence demand for non-toxic, stable, optical solid absorbers, particularly in the visible and near-infrared regions enabling deep tissue penetration. The most popular gold nanorods (GNR) suffer from cumbersome synthesis with poor reproducibility and stability under moderate laser exposure. Recently, a new class of nanoparticle, gold-gold sulfide (GGS), was recognized to have strong NIR absorption but lack colloidal stability. Here, we successfully synthesized a portfolio of aqueous GGS nanoparticles (NP) with excellent stability through a one-step, reproducible synthesis: Anionic, cationic, and protein-coated GGS NPs were obtained by using 3-mercaptopropionic acid (3MPA), branched poly(ethyleneimine) (bPEI) and bovine serum albumin (BSA) as a coating. All GGS NPs comprise small (30 nm) morphologies and display two absorption bands centered at 530-540 nm and 800-900 nm. The photoacoustic activity (PA) of GGS NPs in solution at the visible (532 nm) and NIR (800 nm) region is similar and independent of the coating. Remarkably, they outperformed the spherical gold NPs and performed comparable to GNRs. In vitro PA microscopy images recorded with visible and NIR lasers revealed that GGS NPs are successfully internalized by triple-negative MDA-MB-231 breast cancer cells, used for the proof of principle. A coating-dependent intracellular PA signal in favor of GGS-3MPA was observed. The weakest signal was obtained with the GGS-BSA, indicating a low cellular uptake. These stable, aqueous GGS NPs emerge as promising candidates for broad-band PAI and further biomedical applications.State Planning Organization of Turkiye (DPT) ; TÜBİTAK ; Horizon 2020 Framework ProgrammePublisher versio
Measuring the effect of repetitive stretching on the deformability of human red blood cells using optical tweezers
No full textMechanical features of cells play a crucial role in many biological processes such as crawling, proliferation, spreading, stretching, contracting, division, and programmed cell death. The loss of cell viscoelasticity underlines different types of diseases such as cancer, sickle cell, malaria, and diabetes mellitus. To understand the loss of viscoelasticity, mechanical responses of various kinds of cells to stress or strain are under investigation. Especially red blood cells (RBCs) or erythrocytes are one of the simple structured cells such that the effects of stress or strain could be easily assessed. With their viscoelastic nature, they can deform by preserving cell integrity when passing through blood vessels that are smaller than their size. In this study, we investigated the mechanical response of RBCs under repetitive stretching-relaxation cycles and examined some of the universal cytoskeleton laws at the single cell level over the whole body. For this, the individual RBCs were exposed to repetitive biaxial stretch-relaxation cycles of 5 s duration by optical tweezers to assess their mechanical response. According to the findings, the cells became stiffer with each stretch and became completely undeformable after a certain number of stretch-relaxation cycles. We observed that with the increasing number of stretching cycles, cell stiffness changed as a sign of weak power law, implying cell rheology is scale-free and decay times were increased, showing the transition from fast to slow regime. In addition, the appearance of the cells became non-uniform with darker areas in some parts and highly elongated shape in the most extreme cases.Directorate of Presidential Strategy and Budget of Turkiye ; TÜBİTAKPublisher versio