88 research outputs found

    Customer Engagement in Online Communities: A New Conceptual Framework Integrating Motives, Incentives and Motivation

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    Only a match between user’s motives and incentives enables an engaging online community. The purpose of this paper is to synthesize the literature on user motivation in online communities into a conceptual framework. The framework categorizes motivational factors along motives and potential incentives and integrates the three major motives need for power, need for achievement and need for affiliation as well as the perspective of outcome- and action-related motivation. Psychological models, which explain motivation as an interrelation between different personal motives and situational incentives, demonstrate that effective incentives have to address matching motives. This paper adds to the existing literature by proposing a conceptual framework, which transfers theory of motivation psychology to the context of engagement in online communities and helps to apply successful incentives

    Online algorithms for conversion problems : an approach to conjoin worst-case analysis and empirical-case analysis

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    A conversion problem deals with the scenario of converting an asset into another asset and possibly back. This work considers financial assets and investigates online algorithms to perform the conversion. When analyzing the performance of online conversion algorithms, as yet the common approach is to analyze heuristic conversion algorithms from an experimental perspective, and to analyze guaranteeing conversion algorithms from an analytical perspective. This work conjoins these two approaches in order to verify an algorithms\u27 applicability to practical problems. We focus on the analysis of preemptive and non-preemptive online conversion problems from the literature. We derive both, empirical-case as well as worst-case results. Competitive analysis is done by considering worst-case scenarios. First, the question whether the applicability of heuristic conversion algorithms can be verified through competitive analysis is to be answered. The competitive ratio of selected heuristic algorithms is derived using competitive analysis. Second, the question whether the applicability of guaranteeing conversion algorithms can be verified through experiments is to be answered. Empirical-case results of selected guaranteeing algorithms are derived using exploratory data analysis. Backtesting is done assuming uncertainty about asset prices, and the results are analyzed statistically. Empirical-case analysis quantifies the return to be expected based on historical data. In contrast, the worst-case competitive analysis approach minimizes the maximum regret based on worst-case scenarios. Hence the results, presented in the form of research papers, show that combining this optimistic view with this pessimistic view provides an insight into the applicability of online conversion algorithms to practical problems. The work concludes giving directions for future work.Ein Conversion Problem befasst sich mit dem Eintausch eines Vermögenswertes in einen anderen Vermögenswert unter Berücksichtigung eines möglichen Rücktausches. Diese Arbeit untersucht Online-Algorithmen, die diesen Eintausch vornehmen. Der klassische Ansatz zur Performanceanalyse von Online Conversion Algorithmen ist, heuristische Algorithmen aus einer experimentellen Perspektive zu untersuchen; garantierende Algorithmen jedoch aus einer analytischen. Die vorliegende Arbeit verbindet diese beiden Ansätze mit dem Ziel, die praktische Anwendbarkeit der Algorithmen zu überprüfen. Wir konzentrieren uns auf die Analyse des präemtiven und des nicht-präemtiven Online Conversion Problems aus der Literatur und ermitteln empirische sowie analytische Ergebnisse. Kompetitive Analyse wird unter Berücksichtigung von worst-case Szenarien durchgeführt. Erstens soll die Frage beantwortet werden, ob die Anwendbarkeit heuristischer Algorithmen durch Kompetitive Analyse verifiziert werden kann. Dazu wird der kompetitive Faktor von ausgewählten heuristischen Algorithmen mittels worst-case Analyse abgeleitet. Zweitens soll die Frage beantwortet werden, ob die Anwendbarkeit garantierender Algorithmen durch Experimente überprüft werden kann. Empirische Ergebnisse ausgewählter Algorithmen werden mit Hilfe der Explorativen Datenanalyse ermittelt. Backtesting wird unter der Annahme der Unsicherheit über zukünftige Preise der Vermögenswerte durchgeführt und die Ergebnisse statistisch ausgewertet. Die empirische Analyse quantifiziert die zu erwartende Rendite auf Basis historischer Daten. Im Gegensatz dazu, minimiert die Kompetitive Analyse das maximale Bedauern auf Basis von worst-case Szenarien. Die Ergebnisse, welche in Form von Publikationen präsentiert werden, zeigen, dass die Kombination der optimistischen mit der pessimistischen Sichtweise einen Rückschluss auf die praktische Anwendbarkeit der untersuchten Online-Algorithmen zulässt. Abschließend werden offene Forschungsfragen genannt

    ECCO essential requirements for quality cancer care : Melanoma

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    Background ECCO essential requirements for quality cancer care (ERQCC) are explanations and descriptions of challenges, organisation and actions that are necessary to give high-quality care to patients who have a specific type of cancer. They are written by European experts representing all disciplines involved in cancer care. ERQCC papers give oncology teams, patients, policymakers and managers an overview of the elements needed in any healthcare system to provide high quality of care throughout the patient journey. References are made to clinical guidelines and other resources where appropriate, and the focus is on care in Europe. Melanoma: essential requirements for quality care: Melanoma, the most-deadly skin cancer, is rising in incidence among fair-skinned people in Europe. Increasing complexity of care for advanced disease in clinical areas such as staging and new therapies requires attention to a number of challenges and inequalities in a diverse patient group. Care for advanced melanoma must only be carried out in, or in collaboration with, specialist melanoma centres which have both a core multidisciplinary team and an extended team of allied professionals, and which are subject to quality and audit procedures. Access to such units is far from universal in all European countries. It is essential that, to meet European aspirations for high-quality comprehensive cancer control, healthcare organisations implement the requirements in this paper, paying particular attention to multidisciplinarity and patient-centred pathways from diagnosis to treatment and follow-up, to improve survival and quality of life for patients. Conclusion: Taken together, the information presented in this paper provides a comprehensive description of the essential requirements for establishing a high-quality service for melanoma. The ERQCC expert group is aware that it is not possible to propose a 'one size fits all' system for all countries, but urges that access to multidisciplinary teams and specialised treatments is guaranteed to all patients with melanoma.Peer reviewe

    The German National Registry of Primary Immunodeficiencies (2012-2017)

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    Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1–25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0–88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE- syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%—subcutaneous; 29%—intravenous; 1%—unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment

    Hyperoxemia and excess oxygen use in early acute respiratory distress syndrome : Insights from the LUNG SAFE study

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    Publisher Copyright: © 2020 The Author(s). Copyright: Copyright 2020 Elsevier B.V., All rights reserved.Background: Concerns exist regarding the prevalence and impact of unnecessary oxygen use in patients with acute respiratory distress syndrome (ARDS). We examined this issue in patients with ARDS enrolled in the Large observational study to UNderstand the Global impact of Severe Acute respiratory FailurE (LUNG SAFE) study. Methods: In this secondary analysis of the LUNG SAFE study, we wished to determine the prevalence and the outcomes associated with hyperoxemia on day 1, sustained hyperoxemia, and excessive oxygen use in patients with early ARDS. Patients who fulfilled criteria of ARDS on day 1 and day 2 of acute hypoxemic respiratory failure were categorized based on the presence of hyperoxemia (PaO2 > 100 mmHg) on day 1, sustained (i.e., present on day 1 and day 2) hyperoxemia, or excessive oxygen use (FIO2 ≥ 0.60 during hyperoxemia). Results: Of 2005 patients that met the inclusion criteria, 131 (6.5%) were hypoxemic (PaO2 < 55 mmHg), 607 (30%) had hyperoxemia on day 1, and 250 (12%) had sustained hyperoxemia. Excess FIO2 use occurred in 400 (66%) out of 607 patients with hyperoxemia. Excess FIO2 use decreased from day 1 to day 2 of ARDS, with most hyperoxemic patients on day 2 receiving relatively low FIO2. Multivariate analyses found no independent relationship between day 1 hyperoxemia, sustained hyperoxemia, or excess FIO2 use and adverse clinical outcomes. Mortality was 42% in patients with excess FIO2 use, compared to 39% in a propensity-matched sample of normoxemic (PaO2 55-100 mmHg) patients (P = 0.47). Conclusions: Hyperoxemia and excess oxygen use are both prevalent in early ARDS but are most often non-sustained. No relationship was found between hyperoxemia or excessive oxygen use and patient outcome in this cohort. Trial registration: LUNG-SAFE is registered with ClinicalTrials.gov, NCT02010073publishersversionPeer reviewe

    Effectiveness of a national quality improvement programme to improve survival after emergency abdominal surgery (EPOCH): a stepped-wedge cluster-randomised trial

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    Background: Emergency abdominal surgery is associated with poor patient outcomes. We studied the effectiveness of a national quality improvement (QI) programme to implement a care pathway to improve survival for these patients. Methods: We did a stepped-wedge cluster-randomised trial of patients aged 40 years or older undergoing emergency open major abdominal surgery. Eligible UK National Health Service (NHS) hospitals (those that had an emergency general surgical service, a substantial volume of emergency abdominal surgery cases, and contributed data to the National Emergency Laparotomy Audit) were organised into 15 geographical clusters and commenced the QI programme in a random order, based on a computer-generated random sequence, over an 85-week period with one geographical cluster commencing the intervention every 5 weeks from the second to the 16th time period. Patients were masked to the study group, but it was not possible to mask hospital staff or investigators. The primary outcome measure was mortality within 90 days of surgery. Analyses were done on an intention-to-treat basis. This study is registered with the ISRCTN registry, number ISRCTN80682973. Findings: Treatment took place between March 3, 2014, and Oct 19, 2015. 22 754 patients were assessed for elegibility. Of 15 873 eligible patients from 93 NHS hospitals, primary outcome data were analysed for 8482 patients in the usual care group and 7374 in the QI group. Eight patients in the usual care group and nine patients in the QI group were not included in the analysis because of missing primary outcome data. The primary outcome of 90-day mortality occurred in 1210 (16%) patients in the QI group compared with 1393 (16%) patients in the usual care group (HR 1·11, 0·96–1·28). Interpretation: No survival benefit was observed from this QI programme to implement a care pathway for patients undergoing emergency abdominal surgery. Future QI programmes should ensure that teams have both the time and resources needed to improve patient care. Funding: National Institute for Health Research Health Services and Delivery Research Programme

    Effectiveness of a national quality improvement programme to improve survival after emergency abdominal surgery (EPOCH): a stepped-wedge cluster-randomised trial

    Get PDF
    BACKGROUND: Emergency abdominal surgery is associated with poor patient outcomes. We studied the effectiveness of a national quality improvement (QI) programme to implement a care pathway to improve survival for these patients. METHODS: We did a stepped-wedge cluster-randomised trial of patients aged 40 years or older undergoing emergency open major abdominal surgery. Eligible UK National Health Service (NHS) hospitals (those that had an emergency general surgical service, a substantial volume of emergency abdominal surgery cases, and contributed data to the National Emergency Laparotomy Audit) were organised into 15 geographical clusters and commenced the QI programme in a random order, based on a computer-generated random sequence, over an 85-week period with one geographical cluster commencing the intervention every 5 weeks from the second to the 16th time period. Patients were masked to the study group, but it was not possible to mask hospital staff or investigators. The primary outcome measure was mortality within 90 days of surgery. Analyses were done on an intention-to-treat basis. This study is registered with the ISRCTN registry, number ISRCTN80682973. FINDINGS: Treatment took place between March 3, 2014, and Oct 19, 2015. 22 754 patients were assessed for elegibility. Of 15 873 eligible patients from 93 NHS hospitals, primary outcome data were analysed for 8482 patients in the usual care group and 7374 in the QI group. Eight patients in the usual care group and nine patients in the QI group were not included in the analysis because of missing primary outcome data. The primary outcome of 90-day mortality occurred in 1210 (16%) patients in the QI group compared with 1393 (16%) patients in the usual care group (HR 1·11, 0·96-1·28). INTERPRETATION: No survival benefit was observed from this QI programme to implement a care pathway for patients undergoing emergency abdominal surgery. Future QI programmes should ensure that teams have both the time and resources needed to improve patient care. FUNDING: National Institute for Health Research Health Services and Delivery Research Programme

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century
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