Simulations on the Accuracy of Laser-Flash Data Analysis Methods

The Laser-Flash thermal diffusivity measurement method can be considered one of the most succesful applications of photothermal techniques. This due to the phenomenological and experimental simplicity and ease of reaching better than 1% accuracy over a wide temperature range. The method is based on observing the temperature rise of the sample back face resulting from the absorption of a laser pulse at the other face. There are various approaches for the data reduction and, especially for high temperature measurements where heat loss effects need to be accounted for, they are based on approximations. This is because the inverse function relating thermal properties and heat exchange conditions with the temperature rise temporal shape is not available in closed form. Therefore, detailed error propagation calculations analyses that would take into account all the steps of the data analysis procedures have not in general been performed for data. In this work, simulations of the noise sensitivity and accuracy of selected data reduction schemes were studied using synthetic data. The work was done in connection with the design of a high temperature laser-flash instrument for the measurement of ceramic composites for fusion reactor applications

Inverse Problem for the Yang-Mills Equations

We show that a connection can be recovered up to gauge from source-to-solution type data associated with the Yang-Mills equations in Minkowski space R1+3. Our proof analyzes the principal symbols of waves generated by suitable nonlinear interactions and reduces the inversion to a broken non-abelian light ray transform. The principal symbol analysis of the interaction is based on a delicate calculation that involves the structure of the Lie algebra under consideration and the final result holds for any compact Lie group.Peer reviewe

A Novel Tool to Mitigate By-Catch Mortality of Baltic Seals in Coastal Fyke Net Fishery

Developing methods to reduce the incidental catch of non-target species is important, as by-catch mortality poses threats especially to large aquatic predators. We examined the effectiveness of a novel device, a "seal sock", in mitigating the by-catch mortality of seals in coastal fyke net fisheries in the Baltic Sea. The seal sock developed and tested in this study was a cylindrical net attached to the fyke net, allowing the seals access to the surface to breathe while trapped inside fishing gear. The number of dead and live seals caught in fyke nets without a seal sock (years 2008-2010) and with a sock (years 2011-2013) was recorded. The seals caught in fyke nets were mainly juveniles. Of ringed seals (Phoca hispida botnica) both sexes were equally represented, while of grey seals (Halichoerus grypus) the ratio was biased (71%) towards males. All the by-caught seals were dead in the fyke nets without a seal sock, whereas 70% of ringed seals and 11% of grey seals survived when the seal sock was used. The seal sock proved to be effective in reducing the by-catch mortality of ringed seals, but did not perform as well with grey seals.201

Detection of Hermitian connections in wave equations with cubic non-linearity

We consider the geometric non-linear inverse problem of recovering a Hermitian connection A from the source-to-solution map of the cubic wave equation square(A)phi + kappa vertical bar phi vertical bar(2) phi = f, where kappa not equal 0 and square(A) is the connection wave operator in the Minkowski space R1+3. The equation arises naturally when considering the Yang-Mills-Higgs equations with Mexican hat type potentials. Our proof exploits the microlocal analysis of non-linear wave interactions, but instead of employing information contained in the geometry of the wave front sets as in previous literature, we study the principal symbols of waves generated by suitable interactions. Moreover, our approach relies on inversion of a novel non-abelian broken light ray transform, a result interesting in its own right.Peer reviewe

Health-Related Quality of Life after Restorative Proctocolectomy : A Cross-Sectional Study

Background and Aims: Patients undergoing restorative proctocolectomy have often suffered from active ulcerative colitis which should be remembered when assessing quality of life after operation. The aim of this study was to explore health-related quality of life after restorative proctocolectomy in those with poor or good pouch function and to compare that to patients with active or inactive ulcerative colitis and to the general population. Material and Methods: Altogether, 282 restorative proctocolectomy patients were investigated. The control group comprised 408 ulcerative colitis patients from the local register. Generic 15D and disease-specific inflammatory bowel disease questionnaire health-related quality of life instruments were used. Population-based data were available for 15D. Pouch function was evaluated with oresland score and colitis activity with simple clinical colitis activity index. Results: 15D results showed that patients with good pouch function had health-related quality of life similar to that of the general population. Health-related quality of life with inflammatory bowel disease questionnaire was equally good in patients with good pouch function (n = 131; 70%) and inactive colitis (n = 95; 63%), and equally impaired in patients with poor pouch function (n = 56; 30%) and active colitis (n = 18; 12%). Conclusion: The majority of patients had health-related quality of life comparable to that in general population. Most patients with active ulcerative colitis are likely to improve their health-related quality of life after successful surgery. These findings are important when informing colitis patients about life after surgery.Peer reviewe

Tensor calculus on noncommutative spaces

It is well known that for a given Poisson structure one has infinitely many star products related through the Kontsevich gauge transformations. These gauge transformations have an infinite functional dimension (i.e., correspond to an infinite number of degrees of freedom per point of the base manifold). We show that on a symplectic manifold this freedom may be almost completely eliminated if one extends the star product to all tensor fields in a covariant way and impose some natural conditions on the tensor algebra. The remaining ambiguity either correspond to constant renormalizations to the symplectic structure, or to maps between classically equivalent field theory actions. We also discuss how one can introduce the Riemannian metric in this approach and the consequences of our results for noncommutative gravity theories.Comment: 17p; v2: extended version, to appear in CQ