| 21. |
- Abramowicz, Konrad, 1983-
(författare)
-
Numerical analysis for random processes and fields and related design problems
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis, we study numerical analysis for random processes and fields. We investigate the behavior of the approximation accuracy for specific linear methods based on a finite number of observations. Furthermore, we propose techniques for optimizing performance of the methods for particular classes of random functions. The thesis consists of an introductory survey of the subject and related theory and four papers (A-D).In paper A, we study a Hermite spline approximation of quadratic mean continuous and differentiable random processes with an isolated point singularity. We consider a piecewise polynomial approximation combining two different Hermite interpolation splines for the interval adjacent to the singularity point and for the remaining part. For locally stationary random processes, sequences of sampling designs eliminating asymptotically the effect of the singularity are constructed.In Paper B, we focus on approximation of quadratic mean continuous real-valued random fields by a multivariate piecewise linear interpolator based on a finite number of observations placed on a hyperrectangular grid. We extend the concept of local stationarity to random fields and for the fields from this class, we provide an exact asymptotics for the approximation accuracy. Some asymptotic optimization results are also provided.In Paper C, we investigate numerical approximation of integrals (quadrature) of random functions over the unit hypercube. We study the asymptotics of a stratified Monte Carlo quadrature based on a finite number of randomly chosen observations in strata generated by a hyperrectangular grid. For the locally stationary random fields (introduced in Paper B), we derive exact asymptotic results together with some optimization methods. Moreover, for a certain class of random functions with an isolated singularity, we construct a sequence of designs eliminating the effect of the singularity.In Paper D, we consider a Monte Carlo pricing method for arithmetic Asian options. An estimator is constructed using a piecewise constant approximation of an underlying asset price process. For a wide class of Lévy market models, we provide upper bounds for the discretization error and the variance of the estimator. We construct an algorithm for accurate simulations with controlled discretization and Monte Carlo errors, andobtain the estimates of the option price with a predetermined accuracy at a given confidence level. Additionally, for the Black-Scholes model, we optimize the performance of the estimator by using a suitable variance reduction technique.
|
|
| 22. |
- Abramowicz, Konrad, 1983-, et al.
(författare)
-
Spline approximation of a random process with singularity
- 2011
-
Ingår i: Journal of Statistical Planning and Inference. - : Elsevier. - 0378-3758 .- 1873-1171. ; 141:3, s. 1333-1342
-
Tidskriftsartikel (refereegranskat)abstract
- Let a continuous random process X defined on [0,1] be (m+β)-smooth, 0m, 0<β1, in quadratic mean for all t>0 and have an isolated singularity point at t=0. In addition, let X be locally like a m-fold integrated β-fractional Brownian motion for all nonsingular points. We consider approximation of X by piecewise Hermite interpolation splines with n free knots (i.e., a sampling design, a mesh). The approximation performance is measured by mean errors (e.g., integrated or maximal quadratic mean errors). We construct a sequence of sampling designs with asymptotic approximation rate n^(m+β) for the whole interval.
|
|
| 23. |
- Abreu, Ilka, et al.
(författare)
-
UHPLC-ESI/TOFMS Determination of Salicylate-like Phenolic Gycosides in Populus tremula Leaves
- 2011
-
Ingår i: Journal of Chemical Ecology. - : Springer Science and Business Media LLC. - 0098-0331 .- 1573-1561. ; 37:8, s. 857-70
-
Tidskriftsartikel (refereegranskat)abstract
- Associations of salicylate-like phenolic glycosides (PGs) with biological activity have been reported in Salix and Populus trees, but only for a few compounds, and in relation to a limited number of herbivores. By considering the full diversity of PGs, we may improve our ability to recognize genotypes or chemotype groups and enhance our understanding of their ecological function. Here, we present a fast and efficient general method for salicylate determination in leaves of Eurasian aspen that uses ultra-high performance liquid chromatography-electrospray ionization/time-of-flight mass spectrometry (UHPLC-ESI/TOFMS). The time required for the liquid chromatography separations was 13.5 min per sample, compared to around 60 min per sample for most HPLC protocols. In leaf samples from identical P. tremula genotypes with diverse propagation and treatment histories, we identified nine PGs. We found the compound-specific mass chromatograms to be more informative than the UV-visible chromatograms for compound identification and when quantitating samples with large variability in PG content. Signature compounds previously reported for P. tremoloides (tremulacin, tremuloidin, salicin, and salicortin) always were present, and five PGs (2'-O-cinnamoyl-salicortin, 2'-O-acetyl-salicortin, 2'-O-acetyl-salicin, acetyl-tremulacin, and salicyloyl-salicin) were detected for the first time in P. tremula. By using information about the formic acid adduct that appeared for PGs in the LTQ-Orbitrap MS environment, novel compounds like acetyl-tremulacin could be tentatively identified without the use of standards. The novel PGs were consistently either present in genotypes regardless of propagation and damage treatment or were not detectable. In some genotypes, concentrations of 2'-O-acetyl-salicortin and 2'-O-cinnamoyl-salicortin were similar to levels of biologically active PGs in other Salicaceous trees. Our study suggests that we may expect a wide variation in PG content in aspen populations which is of interest both for studies of interactions with herbivores and for mapping population structure.
|
|
| 24. |
- Abul-Kasim, Kasim, et al.
(författare)
-
Advanced radiological work-up as an adjunct to decision in early reconstructive surgery in brachial plexus injuries
- 2010
-
Ingår i: Journal of Brachial Plexus and Peripheral Nerve Injury. - : BioMed Central. - 1749-7221. ; 5, s. 14-
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundAs neurophysiologic tests may not reveal the extent of brachial plexus injury at the early stage, the role of early radiological work-up has become increasingly important. The aim of the study was to evaluate the concordance between the radiological and clinical findings with the intraoperative findings in adult patients with brachial plexus injuries.MethodsSeven consecutive male patients (median age 33; range 15-61) with brachial plexus injuries, caused by motor cycle accidents in 5/7 patients, who underwent extensive radiological work-up with magnetic resonance imaging (MRI), computed tomography myelography (CT-M) or both were included in this retrospective study. A total of 34 spinal nerve roots were evaluated by neuroradiologists at two different occasions. The degree of agreement between the radiological findings of every individual nerve root and the intraoperative findings was estimated by calculation of kappa coefficient (К-value). Using the operative findings as a gold standard, the accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the clinical findings and the radiological findings were estimated.ResultsThe diagnostic accuracy of radiological findings was 88% compared with 65% for the clinical findings. The concordance between the radiological findings and the intraoperative findings was substantial (К = 0.76) compared with only fair (К = 0.34) for the clinical findings. There were two false positive and two false negative radiological findings (sensitivity and PPV of 0.90; specificity and NPV of 0.87).ConclusionsThe advanced optimized radiological work-up used showed high reliability and substantial agreement with the intraoperative findings in adult patients with brachial plexus injury.
|
|
| 25. |
- Accinelli, Cesare, et al.
(författare)
-
Dissipation and removal of oseltamivir (Tamiflu) in different aquatic environments
- 2010
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 79:8, s. 891-897
-
Tidskriftsartikel (refereegranskat)abstract
- The antiviral drug oseltamivir (Tamiflu) has received recent attention due to the potential use as a first-line defense against H5N1 and H1N1 influenza viruses. Research has shown that oseltamivir is not removed during conventional wastewater treatments, thus having the potential to enter surface water bodies. A series of laboratory experiments investigated the fate and the removal of oseltamivir in two surface water ecosystems of Japan and in a municipal wastewater treatment plant located in Northern Italy. Persistence of oseltamivir in surface water ranged from non-detectable degradation to a half-life of 53 d. After 40 d, <3% of radiolabeled oseltamivir evolved as (CO2)-C-14. The presence of sediments (5%) led to a significant increase of oseltamivir degradation and mineralization rates. A more intense mineralization was observed in samples of the wastewater treatment plant when applying a long incubation period (40 d). More precisely, 76% and 37% of the initial radioactivity applied as C-14-oseltamivir was recovered as (CO2)-C-14 from samples of the biological tank and effluent water, respectively. Two bacterial strains growing on oseltamivir as sole carbon source were isolated and used for its removal from synthetic medium and environmental samples, including surface water and wastewater. Inoculation of water and wastewater samples with the two oseltamivir-degrading strains showed that mineralization of oseltamivir was significantly higher in both inoculated water and wastewater, than in uninoculated controls. Denaturing gradient gel electrophoresis and quantitative PCR analysis showed that Tamiflu would not affect the microbial population of surface water and wastewater.
|
|
| 26. |
- Accinelli, Cesare, et al.
(författare)
-
Removal of oseltamivir (Tamiflu) and other selected pharmaceuticals from wastewater using a granular bioplastic formulation entrapping propagules of Phanerochaete chrysosporium
- 2010
-
Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 81:3, s. 436-43
-
Tidskriftsartikel (refereegranskat)abstract
- The capacity of the ligninolytic fungus Phanerochaete chrysosporium to degrade a wide variety of environmentally persistent xenobiotics has been largely reported in the literature. Beside other factors, one barrier to a wider use of this bioremediation fungus is the availability of effective formulations that ensure easy preparation, handling and application. In this series of laboratory experiments, we evaluated the efficiency of a granular bioplastic formulation entrapping propagules of P. chrysosporium for removal of four selected pharmaceuticals from wastewater samples. Addition of inoculated granules to samples of the wastewater treatment plant of Bologna significantly increased the removal of the antiviral drug oseltamivir (Tamiflu), and the antibiotics, erythromycin, sulfamethoxazol, and ciprofloxacin. Similar effects were also observed in effluent water. Oseltamivir was the most persistent of the four active substances. After 30d of incubation, approximately two times more oseltamivir was removed in bioremediated wastewater than controls. The highest removal efficiency of the bioplastic formulation was observed with the antibiotic ciprofloxacin. Microbiological DNA-based analysis showed that the bioplastic matrix supported the growth of P. chrysosporium, thus facilitating its adaptation to unusual environment such as wastewater.
|
|
| 27. |
- Acosta, Naydú, et al.
(författare)
-
Equidad en el desarrollo de guias de practica clinica : [The concept of equity when developing clinical practice guidelines]
- 2011
-
Ingår i: Revista de Salud Pública. - 0124-0064. ; 13:2, s. 327-38
-
Tidskriftsartikel (refereegranskat)abstract
- This systematic literature review sought to identify methodologies and technical strategies emphasising healthcare services and outcomes when incorporating the concept of equity into Clinical Practice Guidelines (CPG). 940 references were identified, of which 20 fulfilling the inclusion criteria were selected. While no reports were found describing or evaluating an explicit methodology for incorporating considerations of equity into CPG, some studies revealed related strategies or processes, summarised as follows: 1. Target population involvement during all phases of designing, implementing and evaluating CPG; 2. "Cultural capacity" seen as being necessary in CPGs' "cultural translation" for interventions to have less disparity regarding their application and results; 3. Considering psycho-social factors which could affect implementing CPG, and; 4. Considering system inequities so that any health intervention would also confront risks and obstacles to health care due to socioeconomic status. It was concluded that CPGs could be a potential route for promoting more equitable healthcare effects by standardising health interventions if, by incorporating some of the processes described above, they actively seek to avoid unjust differences in access to and/or the quality of the interventions that they prescribe.
|
|
| 28. |
- Adams, Mike, et al.
(författare)
-
Mutuality as a control for information asymmetry : a historical analysis of the claims experience of mutual and stock fire insur ance companies in Sweden, 1889 to 1939
- 2011
-
Ingår i: Business History. - Ilford, Essex : Cass. - 0007-6791 .- 1743-7938. ; 53:7, s. 1074-1091
-
Tidskriftsartikel (refereegranskat)abstract
- We test two competing arguments regarding the influence of organisational form onunderwritingperformance usingdatafromtheSwedish fireinsuranceindustry for the years 1889 to 1939 – a period of both economic growth and stagnation. Since mutuality is a response to information asymmetry problems, mutual insurers are expected to report lower annual claims relative to premiums than stock insurance companies. However, an alternative view is that stock insurers seek to reduce information asymmetry problems by issuing non-participatory rights insurance contracts with high deductibles that induce risk-sharing between the insurer’s shareholders and policyholders. This implies that stock insurers are likely to report lower annual claims than mutual insurers. Our results show that organisational form is an important determinant of the claims experience of Swedish fire insurers, suggesting that mutuality acts as an effective control for information asymmetries in the market.
|
|
| 29. |
|
|
| 30. |
- Addario, Barbara, 1974-
(författare)
-
Alpha-actinin - an amazing journey through time and species
- 2011
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In eukaryotes, the actin cytoskeleton plays an important role in a large variety of cellular events. Its reorganization is regulated by a plethora of actin-modulating proteins, such as α-actinin. α-actinin is a ubiquitous actin-binding protein that belongs to the spectrin superfamily. This family, besides α-actinin, includes spectrin, dystrophin and utrophin. Phylogenetic analyses have indicated that the family members arose after several intragene duplications and rearrangements of a common ancestral α-actinin isoform. Up to the invertebrate-vertebrate bifurcation, organisms seemed to have a single, calcium-dependent α‑actinin. After the split, invertebrates have kept this single isoform, in contrast to vertebrates that acquired four distinct isoforms. Of the four vertebrate α-actinin isoforms, the two present in non-muscle cells are typically calcium sensitive while the two muscle isoforms are calcium insensitive. α-actinin in higher organisms is characterized by the presence of three distinct structural domains: a highly conserved N-terminal actin-binding domain, a central rod domain with four spectrin repeats and a calcium-binding C terminus with EF-hand motifs. In some primitive organisms, such as protozoa and fungi, the rod domain of α-actinin contains only one or two spectrin repeats. With the completion of an ever increasing number of genomes, new and atypical α‑actinin sequences had been available that have not been characterized yet. To obtain a firmer understanding of the evolutionary history of α-actinin, the main objective of this study was to identify, purify and biochemically characterize atypical α‑actinin or α‑actinin-like proteins of the parasite Entamoeba histolytica and of the fungus Schizosaccharomyces pombe. Our results show that both isoforms, despite the much shorter rod domain, are able to bind and cross-link actin filaments and therefore can be considered genuine α-actinins.
|
|
