Monitoring coastal sea level using reflected GNSS signals

A continuous monitoring of coastal sea level changes is important for human society since it is predicted that up to 332 million people in coastal and low-lying areas will be directly affected by flooding from sea level rise by the end of the 21st century. The traditional way to observe sea level is using tide gauges that give measurements relative to the Earth’s crust. However, in order to improve the understanding of the sea level change processes it is necessary to separate the measurements into land surface height changes and sea surface height changes. These measurements should then be relative to a global reference frame. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed. The GNSS-based tide gauge makes use of both GNSS signals that are directly received and GNSS signals that are reflected from the sea surface. An experimental installation at the Onsala Space Observatory (OSO) shows that the reflected GNSS signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS signals. Furthermore, a comparison of local sea level observations from the GNSS-based tide gauge with two stilling well gauges, located approximately 18 km and 33 km away from OSO, gives a pairwise root-mean-square agreement on the order of 4 cm. This indicates that the GNSS-based tide gauge gives valuable results for sea level monitoring

Sea Level Monitoring Using a GNSS-Based Tide Gauge

A continuous monitoring of sea level changes is important for human society since more than 50% of the world's population live within 60 km of the coast. Sea level is traditionally observed with tide gauges that give measurements relative to the Earth's crust. To improve the understanding of sea level changes it is necessary to perform measurements with respect to the Earth's center of gravity. This can be done with satellite techniques, and thus a GNSS-based tide gauge is proposed that makes use of both GNSS-signals that are directly received and that are reflected on the sea surface. A test installation at the Onsala Space Observatory shows that the reflected GNSS-signals have only about 3 dB less signal-to-noise-ratio than the directly received GNSS-signals. A comparison of relative sea level observations from the GNSS-based tide gauge to traditional tide gauges gives an RMS-agreement on the order of 4 cm

High-rate local sea level monitoring with a GNSS-based tide gauge

We present first results from the analysis of high-rate observations with a GNSS-based tide gauge at the Onsala Space Observatory. The goal is to determine local sea level with high temporal resolution. The GNSS-based tide gauge makes use of right-hand circular polarized GNSS signals that are directly received and left-hand circular polarized GNSS signals that are reflected from the sea surface. An experimental setup of the GNSS-based tide gauge was operated in the spring of 2010 and data were recorded with a sampling rate of 20 Hz. We analyzed data decimated to 1 Hz using different temporal resolution between 5 and 240 seconds, and the resulting time series of local sea level were compared to each other and to results from two stilling well gauges. The comparison with the data from the stilling well gauges shows a common trend. The comparison of the results from analyses with different temporal resolution show consistent results. There is also an indication that the GNSS-based tide gauge might be able to give information on the sea surface state

Dealing with sickness certification – a survey of problems and strategies among general practitioners and orthopaedic surgeons

<p>Abstract</p> <p>Background</p> <p>In order to get sickness benefit a sick-listed person need a medical certificate issued by a physician; in Sweden after one week of self-certification. Physicians experience sick-listing tasks as problematic and conflicts may arise when patients regard themselves unable to work due to complaints that are hard to objectively verify for the physician. Most GPs and orthopaedic surgeons (OS) deal regularly with sick-listing issues in their daily practice. The aim of this study was to explore perceived problems and coping strategies related to tasks of sickness certification among general practitioners (GP) and orthopaedic surgeons (OS).</p> <p>Methods</p> <p>A cross-sectional study about sickness certification in two Swedish counties, with 673 participating GPs and 149 OSs, who answered a comprehensive questionnaire. Frequencies together with crude and adjusted (gender and working years) Odds ratios were calculated.</p> <p>Results</p> <p>A majority of the GPs and OSs experienced problems in sickness certification every week. To assess the patient's work ability, to handle situations when they and the patient had different opinions about the need for sickness absence, and to issue prolongation certificates when the previous was issued by another physician were reported as problematic by a majority in both groups. Both GPs and OSs prolonged sickness certifications due to waiting times in health care or at Social Insurance Office (SIO). To handle experienced problems they used different strategies; OSs issued sickness certificates without personal appointment more often than the GPs, who on the other hand reported having contact with SIO more often than the OSs. A higher rate of GPs experienced support from management and had a common strategy for handling sickness certification at the clinic than the OSs.</p> <p>Conclusion</p> <p>Most GPs and OSs handled sickness certification weekly and reported a variety of problems in relation to this task, generally GPs to a higher extent, and they used different coping strategies to handle the problems.</p

Analysis of single nucleotide polymorphism in the promoter and protein expression of the chemokine Eotaxin-1 in colorectal cancer patients

<p>Abstract</p> <p>Background</p> <p>Previous studies suggest that chemokines (chemotactic cytokines) promote and regulate neoplastic progression including metastasis and angiogenesis. The chemokine eotaxin-1 is a powerful eosinophil attractant but also exerts chemotaxis of other leukocytes. Eotaxin-1 has been implicated in gastrointestinal disorders and may play an important role in colorectal mucosal immunity.</p> <p>Patients and methods</p> <p>The objective of this study was to assess the role of eotaxin-1 in colorectal cancer (CRC). Levels of eotaxin-1 protein in CRC tissues (n = 86) and paired normal mucosa were compared after determination by ELISA. Plasma eotaxin-1 levels from CRC patients (n = 67) were also compared with controls (n = 103) using the same method. Moreover, a TaqMan system was used to evaluate the -384A>G eotaxin-1 gene variant in CRC patients (n = 241) and in a control group (n = 253).</p> <p>Results</p> <p>Eotaxin-1 protein levels in colorectal tumours were significantly (P < 0.0001) higher than in normal tissue. Immunohistochemistry revealed eotaxin-1 expression in stromal cells such as fibroblasts and leukocytes of the CRC tissue. The plasma eotaxin-1 level in CRC patients was lower compared with controls (P < 0.0001). Patients with tumours classified as Dukes' stage B and C had lower levels than patients with tumours in Dukes' stage A. We found no difference in genotype distribution but noted a difference regarding allele distribution (P = 0.036) and a dominance of allele G in rectal cancer patients.</p> <p>Conclusion</p> <p>The up-regulated eotaxin-1 protein expression in cancer tissue may reflect an eotaxin-1 mediated angiogenesis and/or a recruitment of leukocytes with potential antitumourigenic role. We noticed a dominance of the G allele in rectal cancer patients compared with colon cancer patients that was independent of eotaxin-1 expression.</p