Ämnesproven i grundskolans årskurs 9 och specialskolans årskurs 10 årskurs 9, 2013 : Biologi, fysik och kemi, årskurs 9, vårterminen 2013

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Modellering av marknadspåverkan på aktiepriser

En oväntad förlust vid aktiehandel med stora ordrar kan ske till följd av en effekt kallad marknadspåverkan. Marknadspåverkan definieras som den procentuella skillnaden mellan transaktionspriset och marknadspriset om ordern inte nått marknaden. Denna effekt blir tydligare vid handel med stora ordrar eftersom en order då kan behöva genomföras i omgångar. Därmed märks en förändring i efterfrågan av aktien och således ändras priset. Denna prisförändring hade inte ansetts vara en förlust om det inte empiriskt påvisats att den delvis är av temporär karaktär. I dagsläget finns ingen allmänt vedertagen modell för marknadspåverkan. Syftet med projektet är därför att skapa en enkel modell för denna effekt. Modellen togs fram i samarbete med myndigheten Andra AP-fonden då de är intresserade av att använda en sådan modell vid optimering av aktieportföljer. Detta gjordes genom att utgå från en befintlig modell där marknadspåverkan, MI, modelleras enligt MI = c1 V V c2 q: I ekvationen är aktiens volatilitet, V är den genomsnittliga volymen som handlas per dag, är antal tillgängliga aktier på marknaden och q är antal aktier som ordern består av. För att skapa modellen behövdes konstanterna c1 och c2 bestämmas med icke-linjär regression utifrån given data för de nämnda parametrarna. För att göra det krävdes en skattning av marknadspåverkan eftersom denna parameter inte är direkt observerbar. Tre uppsättningar data innehållande information om transaktioner, som är genomförda av Andra AP-fonden, analyserades för att kunna skatta marknadspåverkan på fyra olika sätt. Den första metoden jämförde priset när ordern träffade marknaden med det genomsnittliga transaktionspriset. Den andra metoden jämförde priset för första transaktionen med det genomsnittliga transaktionspriset. Den tredje metoden för skattning jämförde aktiens avkastning från stängningspris mellan två dagar med avkastningen för aktiens referensgrupp för samma tidsperiod. Den fjärde metoden skattade marknadspåverkan genom att jämföra aktiens avkastning med avkastningen för aktiens referensgrupp. Skillnaden var att i det senare fallet var det inte den dagliga avkastningen mellan två stängningspris utan avkastningen från stängningspris till öppningspris nästkommande dag som användes. För varje skattning av marknadspåverkan delades ordrarna upp i fem geografiska regioner och c1 samt c2 beräknades. Inte för någon kombination av skattningsmetod och region lyckades dock ett rimligt resultat erhållas. Detta beror troligtvis på brister i metoderna för hur marknadspåverkan skattas samt brister i modellen. Resultatet kan även vara till följd av stora mängder brus i den erhållna datan

One-year results of a prospective randomized, evaluator-blinded, multicenter study comparing TVT and TVT Secur.

INTRODUCTION AND HYPOTHESIS: The aim of this prospective randomized multicenter study was to compare retropubic tension-free vaginal tape (TVT) with TVT Secur in terms of efficacy and safety. METHODS: We set out to enrol 280 stress urinary incontinent (SUI) women with a half-time interim analysis of short-term cure and adverse events. The short-term results have previously been published. Of the133 randomized women, 125 underwent surgery, and 121 (TVT n = 61, TVT Secur n = 60) were available for follow-up 1 year postsurgery. RESULTS: No significant differences were found between groups regarding demographics or incontinence grade. One year after surgery, both subjective and objective cure rates were significantly lower for TVT Secur than for TVT (subjective cure: TVT 98 %, TVT Secur 80 %, p = 0.03; objective cure: TVT 94 %, TVT Secur 71 % for cough test, p = 0.01; TVT 76 %, TVT Secur 58 % for pad test, p = 0.05 ). Three major complications occurred in the TVT Secur group: one tape erosion into the urethra, one tape inadvertently placed into the bladder, and one immediate postoperative bleeding due to injury to the corona mortis. No major complications occurred in the TVT group. No significant differences were found between groups regarding peroperative bleeding, hospital stay, urge symptoms, residual urinary volume, subjective bladder emptying problems, postoperative urinary tract infections, and minor complications. The TVT Secur group used more antimuscarine medication after surgery than the TVT group (p = 0.03). Median time for surgery was 13 and 22 min for TVT Secur and TVT, respectively (p < 0.0001). CONCLUSION: The TVT Secur procedure had significantly inferior subjective and objective cure rates compared with the retropubic TVT procedure. Three serious adverse events occurred in the TVT Secur group. We therefore discourage further use of TVT Secur

Short-term results of a prospective randomized evaluator blinded multicenter study comparing TVT and TVT-Secur.

INTRODUCTION AND HYPOTHESIS: The aim of this prospective randomized multicenter study was to compare TVT (tension-free vaginal tape) with TVT-Secur in terms of efficacy and safety. METHODS: We set out to enrol 280 stress incontinent women with a half time interim analysis of short-term cure and a continuous registration of adverse events. Of 133 randomized women, 126 were operated and 123 (TVT n = 62, TVT-Secur n = 61) available for 2 months follow-up. RESULTS: No significant differences were found between groups regarding demographics or grade of incontinence. At 2 months follow-up, subjective cure rate following TVT-Secur was significantly lower than for TVT (72% and 92%, respectively, p = 0.01). Three major complications occurred in the TVT-Secur group: tape erosion into the urethra, a tape inadvertently placed inside the bladder, and an immediate postoperative bleeding from the corona mortis. No major complications occurred in the TVT group. No significant differences were found between groups regarding perioperative bleeding, hospital stay, urge symptoms, or postoperative urinary tract infections. Median time for surgery was 13 and 22 min for TVT-Secur and TVT, respectively (p < 0.0001). CONCLUSIONS: In a prospective randomized controlled study, the TVT-Secur procedure had a significantly lower subjective cure rate than the retropubic TVT procedure. Due to this, in addition to three serious complications in the TVT-Secur group, we decided to stop further enrolment after the interim analysis. We discourage from further use of the TVT-Secur

HMG-CoA reductase inhibitors and COVID-19 mortality in Stockholm, Sweden : A registry-based cohort study

Background: The relationship between statin treatment and Coronavirus Disease 2019 (COVID-19) mortality has been discussed due to the pleiotropic effects of statins on coagulation and immune mechanisms. However, available observational studies are hampered by study design flaws, resulting in substantial heterogeneity and ambiguities. Here, we aim to determine the relationship between statin treatment and COVID-19 mortality. Methods and findings: This cohort study included all Stockholm residents aged 45 or older (N = 963,876), followed up from 1 March 2020 until 11 November 2020. The exposure was statin treatment initiated before the COVID-19-pandemic, defined as recorded statin dispensation in the Swedish Prescribed Drug Register between 1 March 2019 and 29 February 2020. COVID-19-specific mortality was ascertained from the Swedish Cause of Death Registry. Hazard ratios (HRs) were calculated using multivariable Cox regression models. We further performed a target trial emulation restricted to initiators of statins.In the cohort (51.6% female), 169,642 individuals (17.6%) were statin users. Statin users were older (71.0 versus 58.0 years), more likely to be male (53.3% versus 46.7%), more often diagnosed with comorbidities (for example, ischemic heart disease 23.3% versus 1.6%), more frequently on anticoagulant and antihypertensive treatments, less likely to have a university-level education (34.5% versus 45.4%), and more likely to have a low disposable income (20.6% versus 25.2%), but less likely to reside in crowded housing (6.1% versus 10.3%).A total of 2,545 individuals died from COVID-19 during follow-up, including 765 (0.5%) of the statin users and 1,780 (0.2%) of the nonusers. Statin treatment was associated with a lowered COVID-19 mortality (adjusted HR, 0.88; 95% CI, 0.79 to 0.97, P = 0.01), and this association did not vary appreciably across age groups, sexes, or COVID-19 risk groups. The confounder adjusted HR for statin treatment initiators was 0.78 (95% CI, 0.59 to 1.05, P = 0.10) in the emulated target trial. Limitations of this study include the observational design, reliance on dispensation data, and the inability to study specific drug regimens. Conclusions: Statin treatment had a modest negative association with COVID-19 mortality. While this finding needs confirmation from randomized clinical trials, it supports the continued use of statin treatment for medical prevention according to current recommendations also during the COVID-19 pandemic

Eosinophilic airway inflammation in asthmatic patients is associated with an altered airway microbiome

Background: Asthmatic patients have higher microbiome diversity and an altered composition, with more Proteobacteria and less Bacteroidetes compared with healthy control subjects. Studies comparing airway inflammation and the airway microbiome are sparse, especially in subjects not receiving anti-inflammatory treatment. Objective: We sought to describe the relationship between the airway microbiome and patterns of airway inflammation in steroid-free patients with asthma and healthy control subjects. Methods: Bronchoalveolar lavage fluid was collected from 23 steroid-free nonsmoking patients with asthma and 10 healthy control subjects. Bacterial DNA was extracted from and subjected to Illumina MiSeq sequencing of the 16S rDNA V4 region. Eosinophils and neutrophils in the submucosa were quantified by means of immunohistochemical identification and computerized image analysis. Induced sputum was obtained, and airway hyperresponsiveness to mannitol and fraction of exhaled nitric oxide values were measured. Relationships between airway microbial diversity and composition and inflammatory profiles were analyzed. Results: In asthmatic patients airway microbial composition was associated with airway eosinophilia and AHR to mannitol but not airway neutrophilia. The overall composition of the airway microbiome of asthmatic patients with the lowest levels of eosinophils but not asthmatic patients with the highest levels of eosinophils deviated significantly from that of healthy subjects. Asthmatic patients with the lowest levels of eosinophils had an altered bacterial abundance profile, with more Neisseria, Bacteroides, and Rothia species and less Sphingomonas, Halomonas, and Aeribacillus species compared with asthmatic patients with more eosinophils and healthy control subjects. Conclusion: The level of eosinophilic airway inflammation correlates with variations in the microbiome across asthmatic patients, whereas neutrophilic airway inflammation does not. This warrants further investigation on molecular pathways involved in both patients with eosinophilic and those with noneosinophilic asthma