DYNAMIC PORTFOLIO STRATEGY - USING A MULTIVARIATE GARCH MODEL

This paper examines if it is possible to achieve a higher cumulative and risk adjusted return through an active portfolio strategy compared to a passive portfolio strategy. This is done through a mean-variance framework in which the variance is forecasted using two different models. The results show that it is possible achieve a higher cumulative and risk adjusted return by dynamically changing the weights of the assets in the portfolio. Especially if a simple market timing rule is used

Antibodies against Porphyromonas gingivalis in serum and saliva and their association with rheumatoid arthritis and periodontitis. Data from two rheumatoid arthritis cohorts in Sweden

BackgroundPeriodontitis and oral pathogenic bacteria can contribute to the development of rheumatoid arthritis (RA). A connection between serum antibodies to Porphyromonas gingivalis (P. gingivalis) and RA has been established, but data on saliva antibodies to P. gingivalis in RA are lacking. We evaluated antibodies to P. gingivalis in serum and saliva in two Swedish RA studies as well as their association with RA, periodontitis, antibodies to citrullinated proteins (ACPA), and RA disease activity.MethodsThe SARA (secretory antibodies in RA) study includes 196 patients with RA and 101 healthy controls. The Karlskrona RA study includes 132 patients with RA ≥ 61 years of age, who underwent dental examination. Serum Immunoglobulin G (IgG) and Immunoglobulin A (IgA) antibodies and saliva IgA antibodies to the P. gingivalis–specific Arg-specific gingipain B (RgpB) were measured in patients with RA and controls.ResultsThe level of saliva IgA anti-RgpB antibodies was significantly higher among patients with RA than among healthy controls in multivariate analysis adjusted for age, gender, smoking, and IgG ACPA (p = 0.022). Saliva IgA anti-RgpB antibodies were associated with RA disease activity in multivariate analysis (p = 0.036). Anti-RgpB antibodies were not associated with periodontitis or serum IgG ACPA.ConclusionPatients with RA had higher levels of saliva IgA anti-RgpB antibodies than healthy controls. Saliva IgA anti-RgpB antibodies may be associated with RA disease activity but were not associated with periodontitis or serum IgG ACPA. Our results indicate a local production of IgA anti-RgpB in the salivary glands that is not accompanied by systemic antibody production

Reporäntans effekt på den svenska aktiemarknaden : En eventstudie justerad för GARCH-effekter

Studien syftar till att undersöka huruvida det finns ett signifikant samband mellan den svenska reporäntan och prisbildningen av aktier inkluderade i indexet OMXS30. Datamaterialet täcker perioden 2004 till 2012 och hämtas direkt från NASDAQ OMX Nordic. Genom en eventstudie och med hjälp av Marknadsmodellen estimeras en abnormal avkastning för händelseperioderna. För att ta hänsyn till de estimeringsproblem som finns associerade med finansiell tidsseriedata och dess varians används en EGARCH-modell. Resultatet tyder på en signifikant negativ korrelation mellan reporäntan och marknadspriserna på Stockholmsbörsen. Det finns även indikationer på att en asymmetri existerar vad gäller negativa och positiva nyheters inverkan på variansen

Hur omfattande är e-mobbning på ett IT-gymnasium?

With the very fast development within the area of information technology and the fact that the youth of today are very quick to learn about the new technology, a threat has developed. The technology can be misused in several ways aiming at causing other individuals damage, among other things bullying. Since bullying to a large extent takes place in school among children and young people, I have chosen to carry out a survey about how widespread e-bullying is. I chose to do the survey on a computer - and technology intensive IT upper secondary school, where each pupil has access to a portable computer with wireless Internet. Having in mind that I work at an IT upper secondary school, it was quite natural to choose precisely an IT upper secondary school, but because of that those students probably use the new technology more frequently than other young people in general. The issue became thus. ”How common is it with e-bullying at an IT upper secondary school?” and also ”Is it more common with e-bullying than traditional bullying?” The survey's main aspects were to let the students reply on a quantitative questionnaire that was placed on a web platform, which they reached on the Internet. More or less 50% of the school's students replied on the questionnaire and each surely distributed over the classes 1 to 3, with a bigger percentage of girls than of boys. The survey showed that it was not particularly common with bullying through electronic mediums compared with traditional ways. Only 21% of the students that gave themselves out as being bullied (31 % of all that been asked) stated that this happened through e-bullying of some kind. On the wide question if they thought that it was common with bullying on the Internet, 36,6 % replied that it was very common or quite common. When they got the question about if it was common with bullying via SMS/MMS 17% replied that it was very common or quite common. As to the question of ”What is the most occurring the bullying way, according to your experience?” only 5,6% replied with any off the alternatives SMS/MMS, MSN/Messenger, other chat, Communities or other from the Internet. When I compared my survey with the one that Friends did, I saw that it is not more common with e-bullying at an IT upper secondary school than any other upper secondary school and that it is not more common with e-bullying than traditional bullying. Instead it is much more common with traditional bullying than e-bullying

Reporäntans effekt på aktiekurser

Syftet med denna studie är att undersöka om det finns ett signifikant samband mellan ändringar i den svenska reporäntan och aktiekurser. Utifrån marknadsmodellen har vi påvisat att det råder signifikant negativ korrelation mellan de faktiska ränteändringarna och aktiepriser

Systemutvecklares erfarenhet av arbete med Design Patterns

Validerat; 20101217 (root

Antibodies to citrullinated peptides in serum and saliva in patients with rheumatoid arthritis and their association to periodontitis

Objective A connection between prevalence of rheumatoid arthritis (RA) and periodontitis has been reported. The hypothesis for this association involves increased citrullination in the oral mucosa in patients with periodontitis. Whether ongoing periodontitis has an effect on IgA antibodies to citrullinated peptides (ACPA) in saliva is unknown. We studied IgA ACPA in saliva and serum and their relation to periodontitis and smoking in a population-based elderly RA cohort. Methods A population-based cohort of patients with RA ≥61 years of age (n=132) was examined by rheumatologists and a dental hygienist. Analyses of IgG ACPA in serum and IgA ACPA in serum and saliva were performed. The presence of ACPA was compared in patients with RA with and without periodontitis. Results IgA ACPA in serum occurred in 35% of RA patients with periodontitis and in 43% of RA patients without periodontitis (p=0.740). IgG ACPA in serum was found in 66% of RA patients with periodontitis, and in 69% without periodontitis (p=0.740). IgA ACPA in saliva occurred in 20% with periodontitis and 55% without periodontitis (p=0.062). A logistic regression analysis adjusting for age, gender and smoking gave an odds ratio (OR) of 0.456 (95% CI=0.183-1.137, p=0.092) for saliva IgA ACPA positive individuals to have periodontitis. Conclusion IgA ACPA in serum or saliva was not more common in RA patients with periodontitis. This implies that local production of ACPA by the oral mucosa is not enhanced by periodontal inflammation, in patients with established RA

Antibodies against Porphyromonas gingivalis in serum and saliva and their association with rheumatoid arthritis and periodontitis : Data from two rheumatoid arthritis cohorts in Sweden

Background: Periodontitis and oral pathogenic bacteria can contribute to the development of rheumatoid arthritis (RA). A connection between serum antibodies to Porphyromonas gingivalis (P. gingivalis) and RA has been established, but data on saliva antibodies to P. gingivalis in RA are lacking. We evaluated antibodies to P. gingivalis in serum and saliva in two Swedish RA studies as well as their association with RA, periodontitis, antibodies to citrullinated proteins (ACPA), and RA disease activity. Methods: The SARA (secretory antibodies in RA) study includes 196 patients with RA and 101 healthy controls. The Karlskrona RA study includes 132 patients with RA ≥ 61 years of age, who underwent dental examination. Serum Immunoglobulin G (IgG) and Immunoglobulin A (IgA) antibodies and saliva IgA antibodies to the P. gingivalis–specific Arg-specific gingipain B (RgpB) were measured in patients with RA and controls. Results: The level of saliva IgA anti-RgpB antibodies was significantly higher among patients with RA than among healthy controls in multivariate analysis adjusted for age, gender, smoking, and IgG ACPA (p = 0.022). Saliva IgA anti-RgpB antibodies were associated with RA disease activity in multivariate analysis (p = 0.036). Anti-RgpB antibodies were not associated with periodontitis or serum IgG ACPA. Conclusion: Patients with RA had higher levels of saliva IgA anti-RgpB antibodies than healthy controls. Saliva IgA anti-RgpB antibodies may be associated with RA disease activity but were not associated with periodontitis or serum IgG ACPA. Our results indicate a local production of IgA anti-RgpB in the salivary glands that is not accompanied by systemic antibody production. Copyright © 2023 Svärd, Kastbom, Ljungberg, Potempa, Potempa, Persson, Renvert, Berglund and Söderlin