Forecasting Expected Shortfall: An Extreme Value Approach

We compare estimates of Value at Risk and Expected Shortfall from AR(1)-GARCH(1,1)-type models (standard GARCH, GJR-GARCH, Component GARCH), to estimates produced using the Peak Over Threshold method on the residuals of these models. We find that the conditional volatility model matters less than the choice of distribution for the innovations in the loss process, for which we compare the normal and the t-distribution. The Peak Over Threshold estimates are found to improve upon the estimates of the original models, particularly in the case of normally distributed innovations

Comparison of two methods of fatigue testing bone cement

Two different methods have been used to fatigue test four bone cements. Each method has been used previously, but the results have not been compared. The ISO 527-based method tests a minimum of 10 samples over a single stress range in tension only and uses Weibull analysis to calculate the median number of cycles to failure and the Weibull modulus. The ASTM F2118 test regime uses fewer specimens at various stress levels tested in fully reversed tension–compression, and generates a stress vs. number of cycles to failure (S–N) or Wöhler curve. Data from specimens with pores greater than 1 mm across is rejected. The ISO 527-based test while quicker to perform, provides only tensile fatigue data, but the material tested includes pores, thus the cement is closer to cement in clinical application. The ASTM regime uses tension and compression loading and multiple stress levels, thus is closer to physiological loading, but excludes specimens with defects obviously greater than 1 mm, so is less representative of cement in vivo. The fatigue lives between the cements were up to a factor 15 different for the single stress level tension only tests, while they were only a factor of 2 different in the fully reversed tension–compression testing. The ISO 527-based results are more sensitive to surface flaws, thus the differences found using ASTM F2118 are more indicative of differences in the fatigue lives. However, ISO 527-based tests are quicker, so are useful for initial screening

Kvinnans roll i Indien: En kvalitativ studie om kvinnliga socialarbetares upplevelser av kvinnans roll i Indien

The aim of this study was to research how some female social workers in India, from a professional view, viewed the woman’s role and situation in India, since there are various laws against gender inequality. Research has shown that the implementation of the law, PWDVA, has not been sufficient, as some women still aren’t aware that the law exists. We wanted to find out if they, as professionals, think that the law has done any change for the women’s situation in India. We have done a qualitative study and interviewed six women in an organization in New Delhi, India. The women described that the society in India still has patriarchal values and therefore discrimination against women. We’ve been told about the difference in the gender roles, and that it starts at an early age. What the women told us cannot generalize for all the women in India; it is only the experience of six women. We analyzed our data through gender studies and the conclusion of our survey is that the women have a specific gender role in India and are not as important as a man. Some of the women are working hard to change this, and some women are satisfied with their roles. The awareness levels of women’s rights are low, and therefore the women need to be sensitized

Modified femoral pressuriser generates a longer lasting high pressure during cement pressurisation

<p>Abstract</p> <p>Background</p> <p>The strength of the cement-bone interface in hip arthroplasty is strongly related to cement penetration into the bone. A modified femoral pressuriser has been investigated, designed for closer fitting into the femoral opening to generate higher and more constant cement pressure compared to a commercial (conventional) design.</p> <p>Methods</p> <p>Femoral cementation was performed in 10 Sawbones^®models, five using the modified pressuriser and five using a current commercial pressuriser as a control. Pressure during the cementation was recorded at the proximal and distal regions of the femoral implant. The peak pressure and the pressure-time curves were analysed by student's t-test and Two way ANOVA.</p> <p>Results</p> <p>The modified pressuriser showed significantly and substantially longer durations at higher cementation pressures and slightly, although not statistically, higher peak pressures compared to the conventional pressuriser. The modified pressuriser also produced more controlled cement leakage.</p> <p>Conclusion</p> <p>The modified pressuriser generates longer higher pressure durations in the femoral model. This design modification may enhance cement penetration into cancellous bone and could improve femoral cementation.</p

Zirconia-containing radiopaque mesoporous bioactive glasses

cited By 13International audienceA radiopaque mesoporous bioactive glass (named MBGZ-7) was obtained through a combined sol-gel and evaporation induced self-assembling (EISA) route, adding zirconium propoxide to the synthesis batch as the zirconia precursor. The nitrogen sorption analysis confirmed the mesoporous nature of the glass. The assessment of in vitro bioactivity by soaking in acellular simulated body fluid (SBF) and SEM observation showed the deposition of hydroxyapatite crystals on its surface after one week. The good radiopacity level was demonstrated by comparing X-ray images of MBGZ-7 and a blank sample that did not contain radiopaque additives. It is envisaged the use of MBGZ-7 as a promising dispersed phase in composite materials for minimally invasive surgery procedures, such as injectable bone cements, in order to allow the visualization of the implant under fluoroscopic control, during both injection and follow-up. © 2014 Elsevier B.V

Informationsmiljöer och Intranet

Denna uppsats syftar till att presentera och resonera kring förhållandet mellan informationsmiljöer och Intranet. Begreppet informationsmiljö kan definieras i termer av människor och deras beroendeförhållande till informationssystem, informationsflöden, informationsnätverk, informationsbaser, kunskapsbaser, begreppsbaser, dokumentbaser etc. Enligt vår uppfattning utgör Intranet ett typiskt exempel på en formad informationsmiljö. Efter en analys av informationsmiljöns fyra grundläggande dimensioner visar vi hur samtliga dessa dimensioner bidrar till en mer fullständig förståelse av begreppet Intranet. Informationsmiljöns olika egenskaper gör att vi kan sammanfatta Intranet i fem olika metaforer där Intranet kan ses som ett nätverk av: nätverk, anslagstavlor, samordnade informationssystem, affärsplatser och sociala mötesplatser. Utifrån dessa metaforer har vi slutligen redovisat tre olika generationer av Intranetkonceptets utveckling

Sound Source Localization and Beamforming for Teleconferencing Solutions

In teleconferencing the audio quality is key to conducting successful meetings. The conference room setting imposes various challenges on the speech signal processing, such as noise and interfering signals, reverberation, or participants positioned far from the telephone unit. This work aims at improving the received speech signal of a conference telephone by implementing sound source localization and beamforming. The implemented microphone array signal processing techniques are compared to the performance of an existing multi-microphone solution and evaluated under various conditions using a planar uniform circular array. Recordings of test-sequences for the evaluation were performed using a custom-built array mockup. The implemented algorithms did not show good enough performance to motivate the increased computational complexity compared to the existing solution. Moreover, an increase in number of microphones used was concluded to have little or no effect on the performance of the methods. The type of microphone used was, however, concluded to have impact on the performance and a subjective listening evaluation indicated a preference for omnidirectional microphones which is recommended to investigate further.God ljudkvalitet är en grundsten för lyckade telefonmöten. Miljön i ett konferens-rum medför ett flertal olika utmaningar för behandlingen av mikrofonsignalerna: det kan t.ex. vara brus och störningar, eller att den som talar befinner sig långt från telefonen. Målet med detta arbete är att förbättra den talsignal som tas upp av en konferenstelefon genom att implementera lösningar för lokalisering av talaren och riktad ljudupptagning med hjälp av ett flertal mikrofoner. De implementerade metoderna jämförs med en befintlig lösning och utvärderas under olika brusscenarion för en likformig cirkulär mikrofonkonstellation. För utvärderingen användes testsignaler som spelades in med en specialbyggd enhet. De implementerade algoritmerna kunde inte uppvisa en tillräcklig förbättring i jämförelse med den befintliga lösningen för att motivera den ökade beräkningskomplexitet de skulle medföra. Dessutom konstaterades att en fördubbling av antalet mikrofoner gav liten eller ingen förbättring på metoderna. Vilken typ av mikrofon som användes konstaterades däremot påverka resultatet och en subjektiv utvärdering indikerade en preferens för de rundupptagande mikrofonerna, en skillnad som föreslås undersökas vidare

Eco2Trainer möter serious gaming

Arbetets syfte är att studera om en ansats baserad på serious gaming kan göra ett datorbaserat träningsverktyg mer självständigt och mer motiverande för användaren.  I detta arbete beskrivs erfarenheterna från en fallstudie där ett speciellt träningsverktyg, Eco2Trainer, utvärderades med hjälp av användartest. Eco2Trainer är ett träningsverktyg för sparsam körning med buss. Träningen görs framför en dator med en ratt och pedaler. Arbetets syfte är att med hjälp av serious gaming göra Eco2Trainer självständig och mer motiverande för användaren. Arbetet baseras på ett uppdrag av StageIT AB och innefattar flera intressanta och aktuella delar. Serious gaming är en aktuell ansats som lämpar sig bra för just detta projekt och även psykologiska faktorer som driver en tv- och datorspelare generellt och hur dessa gynnsamma faktorer kan implementeras i ett träningsverktyg som Eco2Trainer beskrivs. Arbetet innefattar litteraturstudier men också användarstudier i form av två användartest med personer i målgruppen. Under användartesten gjordes observationer och frågeformulär besvarades av testdeltagarna. All information samlades ihop och analyserades för att sedan användas för vidare utveckling. Resultatet av arbetet blev en ny version av Eco2Trainer som bygger på ett upplägg baserat på serious gaming. Det nya upplägget testades i ett andra användartest och fick gott betyg av deltagarna. Eco2Trainer visade sig vara självständig och testdeltagarna var motiverade och tyckte det var underhållande. Slutsatsen är därför att projektet har lyckats uppnå sina mål och varit med och skapat en produkt som kan bidraga till en mer miljömedveten framtid.Eco2Trainer is a tool for practicing Ecodriving, developed for busses. In front of a computer screen, with a steering wheel and pedals the training is performed. This method has advantages compared to practicing Ecodriving in a vehicle. No CO2 discharge, no exhaust fumes and no fuel expenses makes Eco2Trainer a tool of today. Making Eco2Trainer more independent and motivating for the user is the purpose of this paper. The project is an assignment for StageIT AB and contains interesting and current topics. Environmental matters are the background of the whole Eco2Trainer project. Serious gaming is another current subject that is brought up and adapt to the project as well as the psychology behind what makes a videogame player, play on. The paper includes literary studies and user studies. The result of this project is a new version of Eco2Trainer were the structure is based on serious gaming. The new version of Eco2Trainer was well liked at the last user test and therefore the conclusion is that the project was successful. The test also shows that the project reaches its goals and helped creating a tool for a more aware future. 

Non-ionic contrast media in acrylic bone cement

Non-ionic, water-soluble, contrast media, iohexol and/or iodixanol, have been investigated for use in acrylic bone cement aimed for arthroplasty. Bone cement, containing the new particulate contrast media , was investigated for: quasi-static mechanical properties, water uptake properties, release of contrast media from the bone cement, biological responses from particulate bone cement, polymerisation reaction, polymerisation temperature, glass transition temperature, injectability and penetration into human cancellous bone, and radiopacity. The quasi-static mechanical properties of acrylic bone cement are influenced by the size and amount of contrast media in the bone cement; the particle size of iodixanol should be above 8 µm in order to have good mechanical properties. At a ratio of 8 wt%, good tensile strength is achieved while creating clear images on a standard X-ray. The molecular weight and glass transition temperature of the cement are not affected by the addition of iodixanol; however, iodixanol does lower the maximum polymerisation temperature. Both iohexol and iodixanol show better biocompatibility than conventional contrast medium; cement particles with iodixanol induce higher bone resorption in vitro than particles with iohexol, and there is a trend that particles with iodixanol show increased bone formation compared to particles with iohexol. The release of iohexol or iodixanol from wet bone cement does not result in a discernable radiolucent zone in the bone cement. The water uptake of cement containing iohexol is significantly higher than that of cement containing iodixanol, which shows higher water uptake than Palacos R. High viscosity cement (Palacos R) achieves better penetration into human cancellous bone in femoral heads than low viscosity cement (Osteopal). Cement containing iodixanol achieves higher bone cement penetration and injectability than low viscosity cement, but lower than Palacos R. The attenuation of X-rays in a contrast medium should be investigated in a standardised way using clinically relevant exposures. Therefore, the attenuation of bone cements (for use in hip- or knee- operations) should be investigated using an X-ray tube voltage of 70 ? 80 kV, with 0.1 m of water as a soft tissue phantom. At 80 kV, with water (similar to clinical situations), iodixanol attenuates photons to the same degree as equal amounts of ZrO2