Seasonal variation of coherence in SAR interferograms in Kiruna,Northern Sweden

This article presents the results of a study conducted to quantify the seasonal variation of coherence in synthetic aperture radar (SAR) interferograms in Kiruna, Northern Sweden. In SAR interferometry (InSAR), coherence is an important concept that provides a good indication of the phase stability of the scatterers. Therefore, in this study, the degree of coherence is used as a parameter to identify the seasonal variation interferograms. For this study, 34 Radarsat-2 ultra-fine beam mode (U6D) images of the Kiruna area (67°51?N, 20°14?E) and the improved digital elevation model (DEM) created by merging the Radarsat-2 DEM and ASTER DEM were used to produce 561 differential interferograms. The interferograms were arranged in three different ways for the analysis, with the first including common master interferograms (with the summer master image), the second including the sequential interferograms that have the shortest temporal baseline, and the third accounting for all possible combinations of the interferograms (full network of interferograms). Following this step, the variation of coherence for forest areas, urban areas, and flat waste rock areas was studied. This study shows that interferograms generated for the Kiruna region exhibit seasonal variations in coherence due to the ground snow layer in winter. Furthermore, when there is water on the ground due to the melting of the snow layer (in the spring) or due to rains in autumn, the coherence is reduced considerably. Another significant feature is that there is a significant change in summer-to-summer coherence for some regions even over the course of a few years. Based on this study, it is clear that the winter Radarsat-2 U6D beam mode images are not suitable for differential interferometric SAR (DInSAR) deformation measurements in flat waste rock regions in Kiruna. It is expected that even with winter images, PSInSAR or CTM techniques will be able to provide better deformation measurements, but, in this study, those techniques were not assessed. The next step will be to study the seasonal variations in coherence in natural or man-made targets/persistent scatterers using persistent scatter InSAR (PSInSAR) or coherence target monitoring (CTM) techniques.     

Treatment of clinical stage I testicular cancer and a possible role for new biological prognostic parameters

Three different treatment strategies for patients with stage I non-seminomatous testicular cancer are available that will all result in long-term survival in more than 98% of the patients: a "wait and see" strategy with follow-up and chemotherapy in cases of tumour progression, retroperitoneal lymphadenectomy, with or without application of systemic chemotherapy, in cases of retroperitoneal metastases (pathological stage II disease) or primary adjuvant chemotherapy following inguinal orchiectomy. Each treatment strategy is associated with specific side-effects. In several studies histological characteristics of the primary tumour, particularly the presence of vascular invasion and of embryonal carcinoma cells, have been demonstrated to be significant prognostic factors for the risk of occult retroperitoneal metastases in patients with stage I disease. In addition, new biological prognostic factors determined by flow cytometry, cytogenetic analysis or molecular-biological DNA or RNA analysis have been investigated, among which alterations of the p53 tumour-suppressor gene may represent a promising new prognostic factor. Although alterations of p53 gene expression seem to be associated with advanced tumour stage and may predict retroperitoneal metastatic disease, the independent role of these molecular genetic alterations needs to be prospectively studied. Currently a risk-adapted treatment strategy based on the histological criteria of vascular invasion and the presence of embryonal carcinoma can be used to stratify patients into a "high-" and "low-risk" group with respect to tumour progression. While primary-nerve-sparing retroperitoneal lymphadenectomy or adjuvant chemotherapy with two cycles of platinum, etoposide and bleomycin may be appropriate for patients with a high risk (above 40%) for tumour progression, a "wait-and-see" strategy can be used for "low-risk" (less than 15% risk of progression) patients. Molecular investigations of prognostic factors may be able to improve further the stratification of patients into these different risk categories.     

The types of circulating fatty acids influence vascular reactivity

The objective of this study was to investigate the relationship between the composition of FA in serum lipids, a marker of dietary fat intake, and vascular reactivity using a combination of cross-sectional and intervention approaches. Fifty-six middle-aged subjects were evaluated in a cross-sectional protocol regarding the relationship between the proportion of FA in serum cholesterol esters and vascular reactivity using measurements of forearm blood flow (FBF) with venous occlusion plethysmography during hyperemia. Another 19 middle-aged subjects were given a rapeseed oil-based diet rich in mono-and polyunsaturated FA or a control diet rich in saturated FA during two consecutive 4-wk periods separated by a 4-wk washout period. In the cross-sectional protocol, the FA 18:0 and 20:3 were positively related to resting FBF, whereas an inverse relationship was seen for the FA 20:5 and 22:6 (P<0.05−0.01). Opposite relationships were seen between these four FA and the relative increase in maximal FBF during hyperemia (P<0.05−0.01). In the intervention protocol, the saturated diet increased resting FBF, as well as the relative increase in maximal FBF during reactive hyperemia, compared to the diet rich in unsaturated FA (P<0.05). Both the cross-sectional and intervention data support the view that the composition of serum FA, which at least partly reflects the quality of dietary fat, plays a role in determinations of vascular reactivity.     

Measurement of Indentation Residual Stresses in Materials Susceptible to Slow Crack Growth

Knowledge of the size and distribution of the indentation residual stress field is important when interpreting slow crack growth data for indented ceramic materials. A technique based on compressively loading indentation cracks has been used to measure the wedging residual stresses at radial indentation cracks. The method also gives information on the fatigue limit and can be applied on any ceramic material susceptible to slow crack growth. Soda–lime glass specimens were indented and the resulting residual stresses, wedging the radial cracks, were measured as a function of indentation load. Calculations of K ₀, the fatigue limit, were made for both virgin indentation cracks and cracks aged until saturation. The magnitude of closing stress needed to prevent slow crack growth was found to depend linearly on the indentation load. For example, for indentation loads of 20 and 60 N, the corresponding closing stresses were 14 and 26 MPa, respectively.     

A Split‐Intein‐Based Method for the Efficient Production of Circularized Nanodiscs for Structural Studies of Membrane Proteins

Phospholipid nanodiscs are a native‐like membrane mimetic that is suitable for structural studies of membrane proteins. Although nanodiscs of different sizes exist for various structural applications, their thermal and long‐term stability can vary considerably. Covalently circularized nanodiscs are a perfect tool to overcome these limitations. Existing methods for the production of circularized nanodiscs can be time‐consuming and technically demanding. Therefore, an easy in vivo approach, in which circularized membrane scaffold proteins (MSPs) can be directly obtained from Escherichia coli culture, is reported herein. Nostoc punctiforme DnaE split‐intein fusions with MSPs of various lengths are used and consistently provide circularized nanodiscs in high yields. With this approach, a large variety of circularized nanodiscs, ranging from 7 to 26 nm in diameter, that are suitable for NMR spectroscopy and electron microscopy (EM) applications can be prepared. These nanodiscs are superior to those of the corresponding linear versions in terms of stability and size homogeneity, which affects the quality of NMR spectroscopy data and EM experiments. Due to their long‐term stability and homogeneity, the presented small circular nanodiscs are suited for high‐resolution NMR spectroscopy studies, as demonstrated with two membrane proteins of 17 or 32 kDa in size. The presented method will provide easy access to circularized nanodiscs for structural studies of membrane proteins and for applications in which a defined and stable nanodisc size is required.     

Ink: designing for performative literary interactions

In this article, we present the interactive literary installation Ink, an experimental installation displayed at the Roskilde library, and the Roskilde Festival, which is designed to prompt public reflection on the nature and role of digital literature. By manipulating three books embedded with sensors, and watching text visualized on a 55” screen, members of the public select from a range of predefined sentences, previously created by a Danish author, and stored in a database. Squeezing the books alters each poetic line by degrees. The final poems print onto a library receipt for their producers and upload to a blog for public viewing. We present (1) design challenges to an installation meant to persuade people to engage affectively with the ergodic nature of digital literature and (2) an in-depth analysis of the empirical findings from the installation studies at the Roskilde Festival. In particular, we highlight the broad, rich range of performative interactions facilitated by the interactive setup. This analysis examines the performative writing and reading achieved by the public through interaction with Ink and also with the resultant poems. From this exploration, we discuss general tendencies when designing affectively engaging literary interactions at the edge of art and design.     

Failure analysis of low velocity impact on thin composite laminates: Experimental and numerical approaches

The dynamic behavior of composite laminates is very complex because there are many concurrent phenomena during composite laminate failure under impact load. Fiber breakage, delaminations, matrix cracking, plastic deformations due to contact and large displacements are some effects which should be considered when a structure made from composite material is impacted by a foreign object. Thus, an investigation of the low velocity impact on laminated composite thin disks of epoxy resin reinforced by carbon fiber is presented. The influence of stacking sequence and energy impact was investigated using load–time histories, displacement–time histories and energy–time histories as well as images from NDE. Indentation tests results were compared to dynamic results, verifying the inertia effects when thin composite laminate was impacted by foreign object with low velocity. Finite element analysis (FEA) was developed, using Hill’s model and material models implemented by UMAT (User Material Subroutine) into software ABAQUS™, in order to simulate the failure mechanisms under indentation tests.     

Life cycle cost considerations in project appraisals of collision-free roads

In the last decade, many single carriageway roads in Sweden have been converted to collision-free roads as a cost-effective alternative to conventional motorways. Investigations have concluded that the road type has been successful in reducing the number of fatal accidents, despite increased operation and maintenance costs. In recent years, the focus has shifted to converting narrower roads which are anticipated to further increase operation and maintenance cost but also complicate traffic management during road works. There are concerns that when life cycle cost is considered in the investment assessment the socioeconomic profitability could be reduced. This article examines this issue by first assessing changes in costs for operation and maintenance using a life cycle cost analysis approach applied on a case study. The results from the analysis were thereafter integrated into a cost–benefit analysis to assess changes in costs in relation to benefits in improved traffic safety and travel time. The analysis indicated profitability even with substantial increase in operation, maintenance and road user work zone costs. Results are discussed from project implementation and road management perspectives.