High-resolution polar low winds obtained from unsupervised sar wind retrieval

High-resolution sea surface observations by spaceborne synthetic aperture radar (SAR) instruments are sorely neglected resources for meteorological applications in polar regions. Such radar observations provide information about wind speed and direction based on wind-induced roughness of the sea surface. The increasing coverage of SAR observations in polar regions calls for the development of SAR-specific applications that make use of the full information content of this valuable resource. Here we provide examples of the potential of SAR observations to provide details of the complex, mesoscale wind structure during polar low events, and examine the performance of two current wind retrieval methods. Furthermore, we suggest a new approach towards accurate wind vector retrieval of complex wind fields from SAR observations that does not require a priori wind direction input that the most common retrieval methods are dependent on. This approach has the potential to be particularly beneficial for numerical forecasting of weather systems with strong wind gradients, such as polar lows

Direct comparison of sea surface velocity estimated from Sentinel-1 and TanDEM-X SAR data

This paper presents the first direct comparison of the sea surface radial velocity (RVL) derived from the two satellite SAR systems Sentinel-1 and TanDEM-X, operating at different frequencies and imaging modes. The RVL is derived from the Doppler centroid (Dc) provided in the Sentinel-1 OCN product and from the along-track interferometric phase of the TanDEM-X. The comparison is carried out using opportunistic acquisitions, collocated in space and time, over three different sites. First, it is observed that the RVL derived from both satellites is biased, thus calibration is applied using the land as a reference. The comparison shows that the correlation and the mean RVL bias between the two datasets depend on the differences in acquisition time, incidence angle and azimuth angle, and on wind and current speed and direction. It is found that, given a time difference of < 20 min, the spatial correlation coefficient is relatively high (between 0.7 and 0.93), which indicates that the two SAR systems observe similar sea surface current fields. The spatial correlation degrades primarily due to increasing time difference and decreasing current magnitudes. The mean RVL bias increases primarily with the radial wind speed, which suggests that the RVL bias is mainly due to the wave-induced Doppler shift. This study shows that under certain conditions, i.e. similar acquisition geometry and short time delay, a good agreement between the two independently derived RVL is achieved. This encourages a synergistic use of the sea surface velocity estimated from different C- and X-band SAR systems

Towards Retrieving Reliable Ocean Surface Currents in the Coastal Zone From the Sentinel-1 Doppler Shift Observations

Recent developments on calibration and partitioning of the signal between the wave and current contributions significantly improve the accuracy of geophysical retrievals from Sentinel-1 Synthetic Aperture Radar-based Doppler shift measurements in the open ocean. In this study, we revise the Sentinel-1B Interferometric Wide products acquired from December 2017 to January 2018 along the coastal zone of northern Norway. We find that the satellite attitude is responsible for 30% of the variation in the Doppler shift observations, while the antenna pattern can describe an additional 15%. The residual variation after recalibration is about 3.8 Hz, corresponding to 0.21–0.15 m/s radial velocity (RVL) depending on the incidence angle. Using recalibrated Sentinel-1 observations, collocated with near-surface wind from MetCoOp-Ensemble Prediction System and sea state from MyWaveWAM, we develop an empirical function (CDOP3SiX) for estimating the sea-state-induced Doppler shift. CDOP3SiX improves the accuracy of sea state contribution estimates under mixed wind fetch conditions and demonstrates that the Norwegian Coastal Current can be detected in the Sentinel-1 derived ocean surface current RVL maps. Moreover, two anticyclonic mesoscale eddies with radial velocities of about 0.5 m/s are detected. The surface current patterns are consistent with the collocated sea surface temperature observations. The Doppler shift observations from Sentinel-1 can therefore be used to study ocean surface currents in the coastal zone with a 1.5 km spatial resolution. Key Points The Sentinel-1 Doppler shift observations are used to retrieve information about the ocean surface currents in the coastal zone Mesoscale eddies are detected in the Synthetic Aperture Radar-derived ocean surface current radial velocity fields Combination of the wind and wave information from collocated models improves the accuracy of the wave-induced contribution estimates Plain Language Summary Knowledge of ocean surface currents is crucial for studies of volume, heat and salt transport, tracking pollutants, and fisheries. The Doppler shift from Sentinel-1 Synthetic Aperture Radar (SAR) observations can be used to retrieve information about ocean surface currents. Challenging calibration and lack of algorithms for separating the wave and current contributions have limited the application of this observation-based method. Recent developments on calibration showed promising improvements in the accuracy of the signal. In this study, we apply this recent calibration method to Sentinel-1B scenes and develop an algorithm applicable for the challenging conditions in the coastal zone. We found that the signal from the Norwegian Coastal Current can be detected in the Sentinel-1 derived ocean surface current radial velocity fields. Also, we demonstrated the potential of SAR data for observing eddies with diameter of about 40–70 km. The Sentinel-1 derived surface currents express meandering structures and boundaries in consistence with the satellite-based sea surface temperature field. Comparison with the ocean model also reveals reasonable agreement, especially for the major surface current features. Therefore, given accurate calibration and new algorithm for removal of the wind and wave contribution, the Sentinel-1 observations can be used for monitoring ocean surface currents in the coastal zone with high spatial resolution.publishedVersio

Actinomycetes from Sediments in the Trondheim Fjord, Norway: Diversity and Biological Activity

The marine environment represents a largely untapped source for isolation of new microorganisms with potential to produce biologically active secondary metabolites. Among such microorganisms, Gram-positive actinomycete bacteria are of special interest, since they are known to produce chemically diverse compounds with a wide range of biological activities. We have set out to isolate and characterize actinomycete bacteria from the sediments in one of the largest Norwegian fjords, the Trondheim fjord, with respect to diversity and antibiotic-producing potential. Approximately 3,200 actinomycete bacteria were isolated using four different agar media from the sediment samples collected at different locations and depths (4.5 to 450 m). Grouping of the isolates first according to the morphology followed by characterization of isolates chosen as group representatives by molecular taxonomy revealed that Micromonospora was the dominating actinomycete genus isolated from the sediments. The deep water sediments contained a higher relative amount of Micromonospora compared to the shallow water samples. Nine percent of the isolates clearly required sea water for normal growth, suggesting that these strains represent obligate marine organisms. Extensive screening of the extracts from all collected isolates for antibacterial and antifungal activities revealed strong antibiotic-producing potential among them. The latter implies that actinomycetes from marine sediments in Norwegian fjords can be potential sources for the discovery of novel anti-infective agents

Immunohistochemical expression of epithelial and stromal immunomodulatory signalling molecules is a prognostic indicator in breast cancer

<p>Abstract</p> <p>Background</p> <p>The immune system has paradoxical roles during cancer development and the prognostic significance of immune modulating factors is controversial. The aim of this study was to determine the expression of cyclooxygenase 2 (COX-2), transforming growth factor-beta (TGF- beta), interleukin-10 (IL-10) and their prognostic significance in breast cancers. Ki67 was included as a measure of growth fraction of tumor cells.</p> <p>Methods</p> <p>On immunohistochemical stained slides from 38 breast cancer patients, we performed digital video analysis of tumor cell areas and adjacent tumor stromal areas from the primary tumors and their corresponding lymph node metastases. COX-2 was recorded as graded staining intensity.</p> <p>Results</p> <p>The expression of TGF-beta, IL-10 and Ki67 were recorded in tumor cell areas and adjacent tumor stromal areas. In both primary tumors and metastases, the expression of COX-2 was higher in the tumor stromal areas than in the tumor cell areas (both <it>P </it>< 0.001). High stromal staining intensity in the primary tumors was associated with a 3.9 (95% CI 1.1-14.2) times higher risk of death compared to the low staining group (<it>P </it>= 0.036). The expression of TGF-beta was highest in the tumor cell areas of both primary tumors and metastases (both <it>P </it>< 0.001). High stromal expression of TGF-beta was associated with increased mortality. For IL-10, the stromal expression was highest in the primary tumors (<it>P </it>< 0.001), whereas in the metastases the expression was highest in tumor cell areas (<it>P </it>< 0.001). High IL-10 expression in tumor- and stromal cell areas of primary tumors predicted mortality. Ki67 was higher expressed in tumor stromal areas of the metastases, and in tumor cell areas of the primary tumors (<it>P </it>< 0.001). Ki67 expression in tumor cell areas and stromal areas of the metastases was independently associated with breast cancer mortality.</p> <p>Conclusions</p> <p>Stromal expression of COX-2, TGF-beta and Ki67 may facilitate tumor progression in breast cancer.</p

Trends in prevalence of ultrasound-assessed carotid atherosclerosis in a general population over time. The Tromsø Study 1994-2016

Background: During the past decades, there has been a shift in risk factor levels in many high-income countries, with decrease in smoking, blood pressure and cholesterol levels, while body mass index, obesity and diabetes increase. The diverging trends may have opposite effects on prevalence of atherosclerosis. We aimed to assess carotid plaque prevalence and the association with risk factor levels in a general population over a period of 22 years. Methods: Prevalence of plaque, number of plaques and total plaque area in the carotid arteries were assessed in three repeated cross-sectional surveys of the population-based Tromsø Study from 1994 through 2016. The number of participants from the first to the last survey was 6362, 7069 and 3021. All surveys included physical examinations, questionnaires, and blood samples. Multivariable logistic regression analysis models were fitted to assess the relationship between risk factors and carotid plaque. Results: We found no significant change in plaque burden over a period of 22 years, neither when measured as plaque presence, plaque number or total plaque area. Plaques were more frequent in men (70%) than in women (59.4%) and increased by age. Systolic blood pressure and smoking increased, while BMI and diabetes decreased over time both in participants with and without plaque. Most risk factors remained higher in participants with plaque than in plaque- free participants while cholesterol levels decreased and reached similar levels in both groups. Age, male sex, systolic blood pressure, smoking, diabetes and HDL cholesterol (inverse) were associated with plaque prevalence. Conclusions: Plaque prevalence remained stable in the observation period. Favorable reductions in systolic blood pressure, cholesterol and smoking may have been partly counteracted by increased diabetes prevalence. Risk factor levels remained higher in participants with plaque than in plaque-free participants, indicating a potential for further improvement in primary prevention of carotid atherosclerosis

Evaluation of error production in animal fluency and its relationship to frontal tracts in normal aging and mild Alzheimer's disease: A combined LDA and time-course analysis investigation

Semantic verbal fluency (VF), assessed by animal category, is a task widely used for early detection of dementia. A feature not regularly assessed is the occurrence of errors such as perseverations and intrusions. So far, no investigation has analyzed the how and when of error occurrence during semantic VF in aging populations, together with their possible neural correlates. The present study aims to address the issue using a combined methodology based on latent Dirichlet allocation (LDA) analysis for word classification together with a time-course analysis identifying exact time of errors’ occurrence. LDA is a modeling technique that discloses hidden semantic structures based on a given corpus of documents. We evaluated a sample of 66 participants divided into a healthy young group (n = 24), healthy older adult group (n = 23), and group of patients with mild Alzheimer’s disease (AD) (n = 19). We performed DTI analyses to evaluate the white matter integrity of three frontal tracts purportedly underlying error commission: anterior thalamic radiation, frontal aslant tract, and uncinate fasciculus. Contrasts of DTI metrics were performed on the older groups who were further classified into high-error rate and low-error rate subgroups. Results demonstrated a unique deployment of error commission in the patient group characterized by high incidence of intrusions in the first 15 s and higher rate of perseverations toward the end of the trial. Healthy groups predominantly showed very low incidence of perseverations. The DTI analyses revealed that the patients with AD committing high-error rate presented significantly more degenerated frontal tracts in the left hemisphere. Thus, our findings demonstrated that the appearance of intrusions, together with left hemisphere degeneration of frontal tracts, is a pathognomic trait of mild AD. Furthermore, our data suggest that the error commission of patients with AD arises from executive and working memory impairments related partly to deteriorated left frontal tracts

Vitamin K2 and its Impact on Tooth Epigenetics

The impact of nutritional signals plays an important role in systemic-based «models» of dental caries. Present hypotheses now focus both on the oral environment and other organs, like the nervous system and brain. The tooth is subjected to shear forces, nourishing and cleansing, and its present “support system” (the hypothalamus/parotid axis) relays endocrine signaling to the parotid gland. Sugar consumption enhances hypothalamic oxidative stress (ROS), reversing dentinal fluid flow, thus creating an enhanced vulnerability to the oral bacterial flora. The acid, produced by the oral bacterial flora, then leads to erosion of the dentine, and an irreversible loss of dental enamel layers. This attack brings about inflammatory responses, yielding metalloproteinase-based “dissolution”. However, vitamin K2 (i.e. MK-4/MK-7) may come to the rescue with its antioxidant property, locally (mouth cavity) or systemically (via the brain), thus sustaining/preserving hormone-induced dentinal fluid flow (encompassing oxidative stress) and boosting/magnifying bodily inflammatory responses. However, sugars may also reduce the tooth’s natural defences through endocrine signaling, thus enhancing acid-supported enamel dentine erosion. Vitamin K2 sustains and improves the salivary buffering capacity via its impact on the secretion/flow of calcium and inorganic phosphates. Interestingly, primitive cultures’ diets (low-sugar and high-K2 diets) preserve dental health

Healthcare professionals' knowledge of modifiable stroke risk factors: A cross-sectional questionnaire survey in greater Gaborone, Botswana

Background - Stroke remains the second leading cause of deaths and disability globally, with highest mortality in Africa (low- and middle-income countries). It is crucial for healthcare professionals to have sufficient stroke risk factors' knowledge in order to reduce the stroke burden. Aims - We investigated healthcare professionals' knowledge of modifiable stroke risk factors, and identified demographic factors influencing this knowledge. Methods - In this cross-sectional survey study from Botswana (upper middle-income country), structured questionnaires reflecting recent stroke guidelines were administered to a representative selection of healthcare workers in greater Gaborone. The response rate was 61.4%, comprising 84 doctors, 227 nurses and 33 paramedics. Categorical data were described using percentages and Chi-square tests. Associations between stroke risk factors' knowledge and demographic factors were analyzed with one-way ANOVA using SPSS 25 statistical software. Results - Awareness rate of individual stroke risk factors was highest for hypertension (96.5%), followed by obesity (93.3%), smoking (91.9%), elevated total cholesterol (91.0%), physical inactivity (83.4%), elevated low-density lipoprotein (LDL) cholesterol (81.1%), excessive alcohol drinking (77.0%), and lowest for diabetes (73.3%). For all-8 risk factors, doctors had the highest knowledge, followed by nurses and paramedics lowest (7.11 vs 6.85 vs 6.06, P < 0.05)