Synthesis of poly(vinyl ether)s with perfluoroalkyl pendant groups

2-Perfluoro(alkyl)ethyl vinyl ethers, F(CF2)nCH2CH2OCHCH2, (n = 6 or 8), were synthesized and polymerized by means of cationic initiators (HI/ZnI2 and CF3SO3H/(CH3)2S). The perfluorohexyl-substituted poly(vinyl ether) is completely amorphous. The polymer with perfluorooctyl segments shows side chain crystallization with a disordering transition. For the corresponding perfluorooctyl monomer a liquid-crystalline phase was observed before melting. Copolymerization experiments of the flurocarbon-segmented monomers with a vinyl ether containing a cyanobiphenyl group in the side chain did not give homogeneous copolymers. This is attributed to the slower rate of polymerization of the fluorinated vinyl ethers as compared with the liquid-crystalline comonomer

A Survey on Point-of-Interest Recommendations Leveraging Heterogeneous Data

Tourism is an important application domain for recommender systems. In this domain, recommender systems are for example tasked with providing personalized recommendations for transportation, accommodation, points-of-interest (POIs), or tourism services. Among these tasks, in particular the problem of recommending POIs that are of likely interest to individual tourists has gained growing attention in recent years. Providing POI recommendations to tourists \emph{during their trip} can however be especially challenging due to the variability of the users' context. With the rapid development of the Web and today's multitude of online services, vast amounts of data from various sources have become available, and these heterogeneous data sources represent a huge potential to better address the challenges of in-trip POI recommendation problems. In this work, we provide a comprehensive survey of published research on POI recommendation between 2017 and 2022 from the perspective of heterogeneous data sources. Specifically, we investigate which types of data are used in the literature and which technical approaches and evaluation methods are predominant. Among other aspects, we find that today's research works often focus on a narrow range of data sources, leaving great potential for future works that better utilize heterogeneous data sources and diverse data types for improved in-trip recommendations.Comment: 35 pages, 19 figure

Analyzing Tourism Online Reviews: An Extended Approach to Hierarchical Topic Detection Using Keyword Clustering

Tourism managers are increasingly turning to the online sphere to gain relevant customer insights. However, current approaches to analyzing vast and rapidly changing user-generated content (UGC) face several limitations. Supervised approaches require significant effort to provide pre-tagged training data and cannot dynamically identify topics mentioned in UGC. On the other hand, unsupervised approaches typically do not support different abstraction levels or enable a successive refinement of analysis in a drill-down manner, which is often expected as a practical requirement of tourism and destination management. Our research objective is, therefore, to extend current supervised approaches for identifying predefined topics by adopting unsupervised approaches using cluster analysis. The results emphasize that unsupervised approaches can (1) detect non-predefined topics dynamically with an accuracy similar to supervised approaches, thus demonstrating the potential to replace them and avoid the necessity of providing pre-tagged training data. (2) To build a topic hierarchy, unsupervised approaches sense more fine-grained topics as an enhancement of predefined topics on a lower level of abstraction, enabling more powerful drill-down-like analyses. Overall, the proposed extended approach to topic detection promises to support tourism management by meaningfully analyzing the increasing mass of visitors’ online feedback

Business intelligence and big data in hospitality and tourism: a systematic literature review

Purpose This paper aims to examine the extent to which Business Intelligence and Big Data feature within academic research in hospitality and tourism published until 2016, by identifying research gaps and future developments and designing an agenda for future research. Design/methodology/approach The study consists of a systematic quantitative literature review of academic articles indexed on the Scopus and Web of Science databases. The articles were reviewed based on the following features: research topic; conceptual and theoretical characterization; sources of data; type of data and size; data collection methods; data analysis techniques; and data reporting and visualization. Findings Findings indicate an increase in hospitality and tourism management literature applying analytical techniques to large quantities of data. However, this research field is fairly fragmented in scope and limited in methodologies and displays several gaps. A conceptual framework that helps to identify critical business problems and links the domains of business intelligence and big data to tourism and hospitality management and development is missing. Moreover, epistemological dilemmas and consequences for theory development of big data-driven knowledge are still a terra incognita. Last, despite calls for more integration of management and data science, cross-disciplinary collaborations with computer and data scientists are rather episodic and related to specific types of work and research. Research limitations/implications This work is based on academic articles published before 2017; hence, scientific outputs published after the moment of writing have not been included. A rich research agenda is designed. Originality/value This study contributes to explore in depth and systematically to what extent hospitality and tourism scholars are aware of and working intendedly on business intelligence and big data. To the best of the authors’ knowledge, it is the first systematic literature review within hospitality and tourism research dealing with business intelligence and big data

Reducing the Impact of Irradiance Ramps on PV Power Production – A Techno-Economic Analysis of Nowcasting

Electricity grids experience an increasing amount of volatile renewable energy integration. This introduces new challenges for the stable operation of the grid and the matching of supply and demand. One of the technical challenges relates to unforeseen short-term power ramps being transmitted to the electrical grids. Such ramps in power production can disrupt grid stability, leading to imbalances, fluctuations in frequency and voltage, potential equipment failures and power outages. Furthermore, they can affect electricity market dynamics, causing price fluctuations. For photovoltaic (PV) power plants the primary source of short-term variability are irradiance ramps caused by clouds. All-sky imagers offer the potential to analyse the current sky conditions and produce shortest-term forecasts (nowcasts) of the irradiance up to 20 minutes into the future. This work investigates the potential of nowcasts for mitigating power ramps through preventive curtailment and analyses the associated economic consequences. For this purpose, irradiance nowcasts for a time frame of one year are fed into a virtual PV plant model located in southern Spain. The model simulates the power output of the plant and thereby processes the irradiance nowcasts into power nowcasts. Several ramp mitigation strategies based on the power nowcasts are developed and assessed. These nowcasting strategies are benchmarked against battery storage strategies, as well as hybrid strategies combining nowcasting and battery storage. The economic performance of the configurations is analysed and compared. For this, an incentive for power smoothing in the form of a monetary penalty for missed ramps is introduced. A simplified simulation of the marketing of the produced electricity determines yearly profits for every configuration which are then used in combination with the overall system costs to calculate the net present values. Using the net present value as a benchmark, a hybrid configuration is found to be the optimal solution for the power control under the applied regulatory framework. It is able to reduce the number of ramps by 93 % while reducing the required battery size by 40 % in comparison to a standalone storage solution. However, the analysis also shows that the introduction of ramp rate regulation and the consequent investment in ramp mitigation and curtailment of energy leads to overall higher levelized costs of energy and lower net present values

Ennia Fortuna: a Roman Glass Maker from Rome?

In der Antikensammlung der Staatlichen Museen zu Berlin befindet sich seit dem frühen 19. Jh. ein römischer Glasboden mit einer Bodenmarke der Ennia Fortuna. Fälschlich wurde das Stück als Boden einer sogenannten Merkurflasche angesehen. Das Fragment stammt allerdings von einer freigeblasenen Flasche und gelangte mit weiteren Stücken der Sammlung Bartholdy aus Rom nach Berlin. Damit ergeben sich hinsichtlich der geographischen und chronologischen Einordnung neue Perspektiven. Freigeblasene Flaschen mit Bodenmarke sind im italischen Raum recht häufig, das Stück mit der Ennia Fortuna-Marke selbst stammt mutmaßlich aus Italien, vielleicht aus Rom und Umgebung, und auch der Name ist dort inschriftlich recht gut vertreten. Damit lässt sich vorschlagen, die Werkstatt der Ennia Fortuna in Rom zu lokalisieren. Eine Verbindung zu dem durch viele signierte Gefäße überlieferten Glasmacher Ennion ist trotz der Namensähnlichkeit nicht herzustellen und eher unwahrscheinlich.The collection of classical antiquities at the Staatliche Museen zu Berlin has held, since the early 19th cent., a base fragment of a Roman glass vessel with a mark of Ennia Fortuna. It was incorrectly taken to be the base of a so-called Mercury flask. The fragment does however come from a free-blown flask and was carried to Berlin from Rome along with other pieces from the Bartholdy Collection. The classification opens up new geographical and chronological perspectives. Free-blown flasks with base marks are relatively common in Italy; the piece with the Ennia Fortuna mark itself comes presumably from Italy, perhaps from Rome and its environs, and the name is also fairly well represented in inscriptions there. It can therefore be proposed that the workshop of Ennia Fortuna was located in Rome. In spite of the similarity in names, a connection with the glass maker Ennion, known from many signed vessels, cannot be established and is in fact unlikely

Angiogenesis in lymph nodes is a critical regulator of immune response and lymphoma growth

Tumor-induced remodeling of the microenvironment in lymph nodes (LNs) includes the formation of blood vessels, which goes beyond the regulation of metabolism, and shaping a survival niche for tumor cells. In contrast to solid tumors, which primarily rely on neo-angiogenesis, hematopoietic malignancies usually grow within pre-vascularized autochthonous niches in secondary lymphatic organs or the bone marrow. The mechanisms of vascular remodeling in expanding LNs during infection-induced responses have been studied in more detail; in contrast, insights into the conditions of lymphoma growth and lodging remain enigmatic. Based on previous murine studies and clinical trials in human, we conclude that there is not a universal LN-specific angiogenic program applicable. Instead, signaling pathways that are tightly connected to autochthonous and infiltrating cell types contribute variably to LN vascular expansion. Inflammation related angiogenesis within LNs relies on dendritic cell derived pro-inflammatory cytokines stimulating vascular endothelial growth factor-A (VEGF-A) expression in fibroblastic reticular cells, which in turn triggers vessel growth. In high-grade B cell lymphoma, angiogenesis correlates with poor prognosis. Lymphoma cells immigrate and grow in LNs and provide pro-angiogenic growth factors themselves. In contrast to infectious stimuli that impact on LN vasculature, they do not trigger the typical inflammatory and hypoxia-related stroma-remodeling cascade. Blood vessels in LNs are unique in selective recruitment of lymphocytes via high endothelial venules (HEVs). The dissemination routes of neoplastic lymphocytes are usually disease stage dependent. Early seeding via the blood stream requires the expression of the homeostatic chemokine receptor CCR7 and of L-selectin, both cooperate to facilitate transmigration of tumor and also of protective tumor-reactive lymphocytes via HEV structures. In this view, the HEV route is not only relevant for lymphoma cell homing, but also for a continuous immunosurveillance. We envision that HEV functional and structural alterations during lymphomagenesis are not only key to vascular remodeling, but also impact on tumor cell accessibility when targeted by T cell-mediated immunotherapies

Regulation of Dendritic Cell Migration to the Draining Lymph Node: Impact on T Lymphocyte Traffic and Priming

Antigen-pulsed dendritic cells (DCs) are used as natural adjuvants for vaccination, but the factors that influence the efficacy of this treatment are poorly understood. We investigated the parameters that affect the migration of subcutaneously injected mouse-mature DCs to the draining lymph node. We found that the efficiency of DC migration varied with the number of injected DCs and that CCR7+/+ DCs migrating to the draining lymph node, but not CCR7−/− DCs that failed to do so, efficiently induced a rapid increase in lymph node cellularity, which was observed before the onset of T cell proliferation. We also report that DC migration could be increased up to 10-fold by preinjection of inflammatory cytokines that increased the expression of the CCR7 ligand CCL21 in lymphatic endothelial cells. The magnitude and quality of CD4+ T cell response was proportional to the number of antigen-carrying DCs that reached the lymph node and could be boosted up to 40-fold by preinjection of tumor necrosis factor that conditioned the tissue for increased DC migration. These results indicate that DC number and tissue inflammation are critical parameters for DC-based vaccination

Differential requirements for the chemokine receptor CCR7 in T cell activation during Listeria monocytogenes infection

Effective priming of T cell responses depends on cognate interactions between naive T cells and professional antigen-presenting cells (APCs). This contact is the result of highly coordinated migration processes, in which the chemokine receptor CCR7 and its ligands, CCL19 and CCL21, play a central role. We used the murine Listeria monocytogenes infection model to characterize the role of the CCR7/CCR7 ligand system in the generation of T cell responses during bacterial infection. We demonstrate that efficient priming of naive major histocompatibility complex (MHC) class Ia–restricted CD8+ T cells requires CCR7. In contrast, MHC class Ib–restricted CD8+ T cells and MHC class II–restricted CD4+ T cells seem to be less dependent on CCR7; memory T cell responses are independent of CCR7. Infection experiments with bone marrow chimeras or mice reconstituted with purified T cell populations indicate that CCR7 has to be expressed on CD8+ T cells and professional APCs to promote efficient MHC class Ia–restricted T cell priming. Thus, different T cell subtypes and maturation stages have discrete requirements for CCR7