Wie viel Grenzwert braucht der Mensch? – Unendlichkeit dynamisch und statisch begreifen

Im Alltag bezeichnet ein Grenzwert eine real messbare Größe, die aus rechtlichen Gründen nicht überschritten werden sollte (z. B. !- oder Feinstaub-Grenzwert). Demgegenüber zeichnet sich der mathematische Grenzwertbegriff gerade dadurch aus, ein theoretisches Gedankenkonstrukt zu sein, welches einem unendlichen Prozess ein idealisiertes Ergebnis zuordnet. Aus didaktischer Perspektive kann somit die Frage aufgeworfen werden, inwiefern eine rein theoretische Auseinandersetzung mit Grenzwerten im Mathematikunterricht überhaupt legitimiert werden kann

Derivation of the non-inferiority margin for the evaluation of direct oral anticoagulants in the treatment of venous thromboembolism

BACKGROUND: Direct oral anticoagulants that target a single coagulation factor have been developed as an alternative to standard therapies with heparin and/or vitamin K antagonists. The purpose of this study was to derive non-inferiority margins suitable for randomised clinical studies designed to evaluate these agents for the treatment of venous thromboembolism (VTE). METHODS: We performed a systematic review to derive non-inferiority margins suitable for use in studies evaluating direct oral anticoagulants for the treatment of VTE. A PubMed search identified publications that evaluated current standard treatment versus placebo, ‘no treatment’ or ‘less intensive treatment’ in patients with symptomatic deep vein thrombosis (DVT) and/or pulmonary embolism (PE). Publications were eligible if they had a randomised study design, included patients with symptomatic DVT and/or PE, used objective diagnostic methods to document the index event and reported objectively confirmed symptomatic recurrent VTE. RESULTS: Fourteen publications were included in the analysis. Recurrent VTE occurred in 25 (1.5%) out of 1715 patients who received current standard of care and in 157 (9.2%) out of 1711 patients who received placebo, ‘no treatment’ or ‘less intensive treatment’, for an odds ratio of 0.18 (95% confidence interval, 0.14−0.25; test for heterogeneity, p=0.87). In order to preserve 50% or 75% of the established treatment effect using a linear scale, the corresponding thresholds for non-inferiority equalled 2.50 and 1.75, respectively. CONCLUSIONS: This systematic review and statistical approach determined non-inferiority margins suitable for use in studies of direct oral anticoagulants for the treatment of DVT and/or PE

Mobile Learning in der Hochschullehre

Sowohl Daniela Schmitz als auch Dominik May und Karsten Lensing haben in ihren Lehrveranstaltungen bereits "mobile learning" eingesetzt. Wie sich mobile learning sinnvoll umsetzen lässt, was bereits im Vorfeld bei der Planung berücksichtigt werden muss, und in welche Fallen man leicht tappen kann, zeigen sie sehr anschaulich in ihrem Beitrag

In vivo testing of a bioabsorbable magnesium alloy serving as total ossicular replacement prostheses

Magnesium alloys have been investigated in different fields of medicine and represent a promising biomaterial for implants due to characteristics like bioabsorbability and osteoinduction. The objective of this study was to evaluate the usability of magnesium as implant material in middle ear surgery. Magnesium implants were placed into the right middle ear of eighteen New Zealand White rabbits. Nine animals were euthanized after four weeks and nine animals after three month. The petrous bones were removed and embedded in epoxy resin. The specimens were then polished, stained and evaluated with the aid of a light microscope. The histological examination revealed a good biocompatibility. After four weeks, a beginning corrosion of the implant's surface and low amount of trabecular bone formation in the area of the stapes base plate was observed. A considerable degradation of implants and obvious bone formation was found three month after implantation. The magnesium alloy used in the present study partly corroded too fast, so that a complete bone reconstruction could not be established in time. The increased osteoinduction on the stapes base plate resulted in a tight bone-implant bonding. Thus, a promising application of magnesium could be a coating of biomaterials in order to improve the bony integration of implants. © The Author(s) 2012 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav

Oral rivaroxaban versus standard therapy for the treatment of symptomatic venous thromboembolism : a pooled analysis of the EINSTEIN-DVT and PE randomized studies

Background: Standard treatment for venous thromboembolism (VTE) consists of a heparin combined with vitamin K antagonists. Direct oral anticoagulants have been investigated for acute and extended treatment of symptomatic VTE; their use could avoid parenteral treatment and/or laboratory monitoring of anticoagulant effects. Methods: A prespecified pooled analysis of the EINSTEIN-DVT and EINSTEIN-PE studies compared the efficacy and safety of rivaroxaban (15 mg twice-daily for 21 days, followed by 20 mg once-daily) with standard-therapy (enoxaparin 1.0 mg/kg twice-daily and warfarin or acenocoumarol). Patients were treated for 3, 6, or 12 months and followed for suspected recurrent VTE and bleeding. The prespecified noninferiority margin was 1.75. Results: 8282 patients were enrolled. 4151 received rivaroxaban and 4131 received standard-therapy. The primary efficacy outcome occurred in 86 rivaroxaban-treated patients (2.1%) compared with 95 (2.3%) standard-therapy-treated patients (hazard ratio, 0.89; 95% confidence interval [CI], 0.66-1.19; pnoninferiority<0.001). Major bleeding was observed in 40 (1.0%) and 72 (1.7%) patients in the rivaroxaban and standard-therapy groups, respectively (hazard ratio, 0.54; 95% CI, 0.37-0.79; p=0.002). In key subgroups, including fragile patients, cancer patients, patients presenting with large clots and those with a history of recurrent VTE, the efficacy and safety of rivaroxaban was similar compared with standard-therapy. Conclusion: The single-drug approach with rivaroxaban resulted in similar efficacy to standard-therapy and was associated with a significantly lower rate of major bleeding. Efficacy and safety results were consistent among key patient subgroups

Comparison of Four Bleeding Risk Scores to Identify Rivaroxaban-treated Patients With Venous Thromboembolism at Low Risk for Major Bleeding

Objectives Outpatient treatment of acute venous thromboembolism (VTE) requires the selection of patients with a low risk of bleeding during the first few weeks of anticoagulation. The accuracy of four systems, originally derived for predicting bleeding in VTE treated with vitamin K antagonists (VKAs), was assessed in VTE patients treated with rivaroxaban. Methods All patients treated with rivaroxaban in the multinational EINSTEIN deep vein thrombosis (DVT) and pulmonary embolism (PE) trials were included. Major bleeding was defined as ≥2 g/dL drop in hemoglobin or ≥2-unit blood transfusion, bleeding in critical area, or bleeding contributing to death. The authors examined the incidence of major bleeding in patients with low-risk assignment by the systems of Ruiz-Gimenez et al. (score = 0 to 1), Beyth et al. (score = 0), Kuijer et al. (score = 0), and Landefeld and Goldman. (score = 0). For clinical relevance, the definition of low risk for all scores except Kuijer includes all patients < 65 years with no prior bleeding history and no comorbid conditions (current cancer, renal insufficiency, diabetes mellitus, anemia, prior stroke, or myocardial infarction). Results A total of 4,130 patients (1,731 with DVT only, 2,399 with PE with or without DVT) were treated with rivaroxaban for a mean (±SD) duration of 207.6 (±95.9) days. Major bleeding occurred in 1.0% (40 of 4,130; 95% confidence interval [CI] = 0.7% to 1.3%) overall. Rates of major bleeding for low-risk patients during the entire treatment period were similar: Ruiz-Gimenez et al., 12 of 2,622 (0.5%; 95% CI = 0.2% to 0.8%); Beyth et al., nine of 2,249 (0.4%; 95% CI = 0.2% to 0.8%); Kuijer et al., four of 1,186 (0.3%; 95% CI = 0.1% to 0.9%); and Landefeld and Goldman, 11 of 2,407 (0.5%; 95% CI = 0.2% to 0.8%). At 30 days, major bleed rates for low-risk patients were as follows: Ruiz-Gimenez et al., five of 2,622 (0.2%; 95% CI = 0.1% to 0.4%); Beyth et al., five of 2,249 (0.2%; 95% CI = 0.1% to 0.5%); Kuijer et al., three of 1,186 (0.3%; 95% CI = 0.1% to 0.7%); and Landefeld and Goldman, seven of 2,407 (0.3%; 95% CI = 0.1% to 0.6%). No low-risk patient had a fatal bleed. Conclusions Four scoring systems that use criteria obtained in routine clinical practice, derived to predict low bleeding risk with VKA treatment for VTE, identified patients with less than a 1% risk of major bleeding during full-course treatment with rivaroxaban

Screening for Post-Stroke Visual Impairment: Implications for Occupational Therapy Practice

The prevalence of post-stroke visual impairment is alarmingly high, with estimates of up to two-thirds of stroke survivors experiencing deficits (Rowe, Hepworth, Howard et al., 2019). However, research indicates that greater than 60% of visual acuity deficits and visual-spatial neglect in patients with stroke are undetected by standard clinical practice (Edwards et al., 2006). Thus, many patients with stroke have clinically significant visual impairments that are not being detected, and therefore, are not being adequately addressed. Visual impairments can substantially influence an individual\u27s everyday functioning, safety, social interaction, and quality of life. Without skilled intervention and support, individuals experiencing these deficits may develop reduced self-efficacy, social isolation, and occupational deprivation (Perea et al., 2018). The aim of this thesis is to spread awareness of the high prevalence and underdiagnosis of post-stroke visual impairment, educate current and future occupational therapy practitioners on recommendations to reduce heterogeneity in assessment practices, and advocate for the role of occupational therapy in improving detection of post-stroke visual impairment to optimize the functional recovery and quality of life of stroke survivors. This knowledge was disseminated in three ways. The first method was to educate occupational therapy practitioners and students via a Minnesota Occupational Therapy Association virtual continuing education session. The second method was to inform readers of the American Occupational Therapy Association’s Rehabilitation and Disability Special Interest Section Quarterly Practice Connection through an article submitted for publication. The final method was to raise awareness and educate occupational therapy practitioners, students, and educators attending the 2021 Iowa Occupational Therapy Association annual conference by presenting a poster. Completion of these three knowledge translation projects generated awareness and greater understanding of the factors resulting in the underdiagnosis of post-stroke visual impairment and affirmed occupational therapy’s role in screening for visual impairments poststroke. However, there is need for continued education aimed at improving knowledge and awareness of the visual problems that can occur after stroke amongst occupational therapists, other members of the stroke care team, and the general public. Furthermore, now that core outcome sets for vision screening and full vision assessment have been developed to assist in reducing the heterogeneity in assessment practices, efforts to disseminate this information to clinicians and researchers involved in screening and assessment of post-stroke visual impairment should be prioritized. Future research should evaluate the use of these outcome sets and attempt to achieve consensus on how the outcomes should be measured