Portfolio-optimization models for small investors

Since 2010, the client base of online-trading service providers has grown significantly. Such companies enable small investors to access the stock market at advantageous rates. Because small investors buy and sell stocks in moderate amounts, they should consider fixed transaction costs, integral transaction units, and dividends when selecting their portfolio. In this paper, we consider the small investor’s problem of investing capital in stocks in a way that maximizes the expected portfolio return and guarantees that the portfolio risk does not exceed a prescribed risk level. Portfolio-optimization models known from the literature are in general designed for institutional investors and do not consider the specific constraints of small investors. We therefore extend four well-known portfolio-optimization models to make them applicable for small investors. We consider one nonlinear model that uses variance as a risk measure and three linear models that use the mean absolute deviation from the portfolio return, the maximum loss, and the conditional value-at-risk as risk measures. We extend all models to consider piecewise-constant transaction costs, integral transaction units, and dividends. In an out-of-sample experiment based on Swiss stock-market data and the cost structure of the online-trading service provider Swissquote, we apply both the basic models and the extended models; the former represent the perspective of an institutional investor, and the latter the perspective of a small investor. The basic models compute portfolios that yield on average a slightly higher return than the portfolios computed with the extended models. However, all generated portfolios yield on average a higher return than the Swiss performance index. There are considerable differences between the four risk measures with respect to the mean realized portfolio return and the standard deviation of the realized portfolio return.

Percutaneous closure of patent foramen ovale in cryptogenic embolism

BACKGROUND The options for secondary prevention of cryptogenic embolism in patients with patent foramen ovale are administration of antithrombotic medications or percutaneous closure of the patent foramen ovale. We investigated whether closure is superior to medical therapy. METHODS We performed a multicenter, superiority trial in 29 centers in Europe, Canada, Brazil, and Australia in which the assessors of end points were unaware of the study-group assignments. Patients with a patent foramen ovale and ischemic stroke, transient ischemic attack (TIA), or a peripheral thromboembolic event were randomly assigned to undergo closure of the patent foramen ovale with the Amplatzer PFO Occluder or to receive medical therapy. The primary end point was a composite of death, nonfatal stroke, TIA, or peripheral embolism. Analysis was performed on data for the intention-to-treat population. RESULTS The mean duration of follow-up was 4.1 years in the closure group and 4.0 years in the medical-therapy group. The primary end point occurred in 7 of the 204 patients (3.4%) in the closure group and in 11 of the 210 patients (5.2%) in the medical-therapy group (hazard ratio for closure vs. medical therapy, 0.63; 95% confidence interval [CI], 0.24 to 1.62; P=0.34). Nonfatal stroke occurred in 1 patient (0.5%) in the closure group and 5 patients (2.4%) in the medical-therapy group (hazard ratio, 0.20; 95% CI, 0.02 to 1.72; P=0.14), and TIA occurred in 5 patients (2.5%) and 7 patients (3.3%), respectively (hazard ratio, 0.71; 95% CI, 0.23 to 2.24; P=0.56). CONCLUSIONS Closure of a patent foramen ovale for secondary prevention of cryptogenic embolism did not result in a significant reduction in the risk of recurrent embolic events or death as compared with medical therapy. (Funded by St. Jude Medical; ClinicalTrials.gov number, NCT00166257.).

Amplatzer left atrial appendage occlusion through a patent foramen ovale

OBJECTIVES: To assess feasibility and outcomes of left atrial appendage (LAA) closure when using a patent foramen ovale (PFO) for left atrial access. Background: Because of the fear of entering the left atrium too high, using a PFO for left atrial access during LAA occlusion (LAAO) is generally discouraged. We report our single-center experience using a concomitant PFO for LAAO, thereby avoiding transseptal puncture. METHODS: LAAO was performed with local anesthesia and fluoroscopic guidance only (no echocardiography). The Amplatzer Cardiac Plug (ACP) was used in all patients. After LAAO, the PFO was closed at the same sitting, using an Amplatzer occluder through the ACP delivery sheath. Patients were discharged the same or the following day on dual antiplatelet therapy for 1-6 months, at which time a follow-up transesophageal echocardiogram (TEE) was performed. RESULTS: In 49 (96%) of 51 patients (35 males, age 70.9 ± 11.9 years), LAAO was successful using the PFO for left atrial access. In one patient, a long tunnel PFO precluded LAAO, which was performed via a more caudal transseptal puncture. In a second patient, a previously inserted ASD occluder precluded LAAO, which was abandoned because of pericardial bleeding. PFO closure was successful in all patients. Follow-up TEE was performed in 43 patients 138 ± 34 days after the procedure. It showed proper sitting of both devices in all patients. CONCLUSIONS: Using a PFO for LAAO had a high success rate and could be the default access in all patients with a PFO, potentially reducing procedural complications arising from transseptal puncture.

New Product Portfolio Performance in Family Firms

This study investigates the relationship between top management team (TMT) innovation orientation and new product portfolio performance in small and medium-sized family firms by exploring two family firm-specific sources of TMT diversity as moderators: the number of generations involved in the TMT and the ratio of family members in the TMT. Results indicate that family-induced diversity in the TMT has opposing moderating effects. Although a positive relationship exists between TMT innovation orientation and new product portfolio performance when multiple generations are involved in the TMT, TMT innovation orientation and new product portfolio performance experience a negative relationship when the ratio of family members in the TMT is high. The study discusses theoretical and managerial implications of the findings and develops avenues for future research.

Transesophageal echocardiography in cryptogenic stroke and patent foramen ovale: analysis of putative high-risk features from the risk of paradoxical embolism database

BACKGROUND Patent foramen ovale (PFO) is associated with cryptogenic stroke (CS), although the pathogenicity of a discovered PFO in the setting of CS is typically unclear. Transesophageal echocardiography features such as PFO size, associated hypermobile septum, and presence of a right-to-left shunt at rest have all been proposed as markers of risk. The association of these transesophageal echocardiography features with other markers of pathogenicity has not been examined. METHODS AND RESULTS We used a recently derived score based on clinical and neuroimaging features to stratify patients with PFO and CS by the probability that their stroke is PFO-attributable. We examined whether high-risk transesophageal echocardiography features are seen more frequently in patients more likely to have had a PFO-attributable stroke (n=637) compared with those less likely to have a PFO-attributable stroke (n=657). Large physiologic shunt size was not more frequently seen among those with probable PFO-attributable strokes (odds ratio [OR], 0.92; P=0.53). The presence of neither a hypermobile septum nor a right-to-left shunt at rest was detected more often in those with a probable PFO-attributable stroke (OR, 0.80; P=0.45; OR, 1.15; P=0.11, respectively). CONCLUSIONS We found no evidence that the proposed transesophageal echocardiography risk markers of large PFO size, hypermobile septum, and presence of right-to-left shunt at rest are associated with clinical features suggesting that a CS is PFO-attributable. Additional tools to describe PFOs may be useful in helping to determine whether an observed PFO is incidental or pathogenically related to CS.

Death by patent foramen ovale in a soccer player

A 34-year-old male patient was referred for primary percutaneous coronary intervention for ST-segment elevation myocardial infarction with cardiogenic shock and was found to have embolic left coronary artery occlusion and subsegmental pulmonary artery emboli as a consequence of venous thrombosis to trauma to the thigh in the presence of a patent foramen ovale.

Swiss Patent Jurisprudence 2012

The new Swiss Federal Patent Court, with nationwide first-instance jurisdiction over all civil patent matters, has been operating since January 1, 2012. This article reviews and contextualizes the most important patent cases published in 2012 by the Swiss Federal Patent Court and the Swiss Federal Supreme Court. More specifically, the article covers cases on issues such as the evidentiary status of party expert opinions, the formal requirements for requests for injunctive relief, the infringement and non-obviousness tests employed by the Swiss Federal Patent Court, the use of reports and statements from technical judges in lieu of expert opinions, and the procedural devices for the pre-trial taking of evidence, in particular the new patent-specific device of precise description. The author suggests that designing the Federal Patent Court to include technically trained judges may lead to a more automatic adoption of the practices and case law of the European Patent Office. The article concludes that the revamped Swiss patent litigation system has the potential of turning Switzerland into a competitive venue for the adjudication of patent matters in Europe.

Lernprozesse dokumentieren, reflektieren und beurteilen. Lerntagebuch und Portfolio in Bildungsforschung und Bildungspraxis

Die Beiträge greifen "den Wandel von einer Lehr- hin zu einer Lernkultur" auf und konzentrieren sich dabei auf "zwei Indikatoren dieses Wandels: die Einführung von Lerntagebüchern und die Implementierung von Portfolios im Bildungsbereich, und zwar im schulischen Unterricht, in der Lehrer-Grundausbildung sowie in der Weiterbildung. Der Lerntagebuch- und Portfolio-Ansatz implizieren eine bestimmte Haltung gegenüber dem Lernen und Lehren. Der Einsatz von Tagebüchern und Portfolios führt Lehrende dazu, ihren Unterricht für neue Zugänge zu öffnen und ihre Rolle als Lernbegleiter/innen und -berater/innen zu professionalisieren. Andererseits erfordern Tagebücher und Portfolios von Lernenden eine aktive, selbstreflexive und eigenverantwortliche Auseinandersetzung mit ihrem Lernprozess. In diesem Band werden zum einen praxisbezogene Erfahrungen, zum anderen aktuelle Erkenntnisse aus der Forschung zum Potenzial des Lerntagebuch- und Portfolio-Ansatzes präsentiert. Jeweils drei bis fünf Beiträge zum Kontext Schule, Hochschule und Weiterbildung sind drei Hauptteilen zugeordnet: 1. Grundüberlegungen zur neuen Lernkultur und zur Arbeit mit Lerntagebuch bzw. Portfolio; 2. Lerntagebücher in Forschung und Praxis; 3. Portfolios in Forschung und Praxis.