Univ., Diss., 2009--Marburg.

The present study focused on methylmercury (MeHg) in emergent aquatic insects and spiders from human-made ponds. This dissertation addresses two main topics: (1) factors affecting variation in spider MeHg concentrations around human-made ponds and (2) the magnitude of MeHg transported out of human-made ponds by emergent aquatic insects (insect-mediated MeHg flux). Spiders were specifically targeted in this study because they have been proposed as sentinels of MeHg contamination (organism whose tissue concentrations reflect the level of MeHg in the environment). Spider MeHg concentrations were related to spider diet, size, and proximity to waterbody, but affected individual spider taxa differently. In a second study, I found that only "large" spiders within a taxa had tissue concentrations positively related to prey MeHg concentrations. These results indicate that the relationship between spider and prey MeHg could be size-dependent and that "large" spiders within a taxa may better reflect ambient MeHg contamination. Finally, I tested a conceptual model hypothesizing insect-mediated MeHg flux from human-made ponds is controlled by pond permanence and fish presence. In agreement with the conceptual model, insect-mediated MeHg flux from ponds was suppressed by the presence of fish, likely due to fish predation on emergent insect larvae. I found the mean aggregate MeHg flux was approximately 6 times higher from ponds without fish than from ponds with fish. The suppression of insect flux by fish was stronger for large insect taxa than small insect taxa. Results of this study indicate that community structure can influence the cross-system transport of contaminants, like MeHg, from ponds to terrestrial food webs.

The introduction of sentinel lymph node biopsy (SLNB) has conveyed several new issues, such as the risk of false negativity, long-term consequences, the prognostic significance of micrometastases and whether ALND can be omitted in sentinel lymph node- (SLN) positive patients. Archived SLN specimens from 50 false negative patients and 107 true negative controls were serially sectioned and stained with immunohistochemistry. The detection rate of previously unknown metastases did not differ between the false and the true negative patients. The risk of false negativity was higher in patients with multifocal or hormone receptor-negative tumours, or if only one SLN was found. In a Swedish multicentre cohort, 2216 SLN-negative patients in whom ALND was omitted were followed up for a median of 65 months. The isolated axillary recurrence rate was only 1.0%, and the overall survival was high (93%). The survival of 3369 breast cancer patients (2383 node-negative (pN0), 107 isolated tumour cells (pN0(i+), 123 micrometastases (pN1mi) and 756 macrometastases (pN1)) was analysed. The 5-year cause-specific and event-free survival was worse for pN1mi and pN1 patients than for pN0 patients. There was no difference in survival between pN0(i+) and pN0 patients. Tumour and SLN characteristics in 869 SLN-positive patients were compared between those with and without non-SLN metastases, and the Tenon score was calculated. The risk of non-SLN metastases was higher in case of SLN macrometastases (compared with micrometastases), a high positive/total SLN ratio and Elston grade 3 tumours, and increased with increasing tumour size. The area under the curve (AUC) for the Tenon score was 0.65, and the test thus performed inadequately in this population. In conclusion, despite the risk of false negativity, SLNB with omission of ALND in SLN-negative patients appears to be safe even in the long term. The presence of micrometastases is of prognostic importance and should entail adjuvant treatment. The need for ALND in patients with SLN micro- and even macrometastases has been questioned, but the occurrence of non-SLN metastases is hard to predict, and strong evidence for the safe omission of ALND is lacking.

A research report submitted to the Faculty of Health Sciences, University of Witwatersrand, in fulfillment of the requirements for the degree of Master of Medicine in the branch of Internal Medicine Johannesburg, 2015 / Lymphadenopathy is a common clinical presentation of disease in South Africa (SA), particularly in the era of Human Immunodeficiency Virus (HIV) and tuberculosis (TB) coinfection. Methods Data from 560 lymph node biopsy reports of specimens from patients older than 12 years at Chris Hani Baragwanath Academic Hospital (CHBAH) between 1 January 2010 and 31 December 2012 was extracted from the National Health Laboratory Service (NHLS), division of Anatomical Pathology. Cytology reports of lymph node fine needle aspirates (FNAs) performed prior to lymph node biopsy in 203 patients were also extracted from the NHLS. Consent was not obtained from participants for their records to be used as patient information was anonymized and de-identified prior to analysis. Results The majority of patients were female (55%) and of the African/black racial group (90%). The median age of patients was 40 years (range12-94). The most common indication for biopsy was an uncertain diagnosis (more than two differential diagnoses entertained), followed by a suspicion for lymphoma, carcinoma and TB. Overall, malignancy constituted the largest biopsy pathology group (39%), with 36% of this group being carcinoma and 27% non-Hodgkin lymphoma. 22% of the total sampled nodes displayed necrotizing granulomatous inflammation (including histopathology and cytology demonstrating definite, and suspicious for mycobacterial infection), 8% comprised HIV reactive nodes; in the remainder no specific pathology was identified (nonspecific reactive lymphoid hyperplasia). Kaposi sarcoma (KS) accounted for 3% of lymph node pathology in this sample. Concomitant lymph node pathology was diagnosed in four cases of nodal KS (29% of the subset). The co-existing pathologies were TB and Castleman disease. HIV-positive patients constituted 49% of this study sample and the majority (64%) of this subset had CD4 counts less than 350 cells/ul. 27% were HIVnegative and in the remaining nodes, the HIV status of patients was unknown. The most common lymph node pathologies in HIV-positive patients were Mycobacterial infection (31%), HIV reactive nodes (15%), non-Hodgkin lymphoma (15%) and nonspecific reactive lymphoid hyperplasia (15%). Only 9% were of Hodgkin lymphoma. In contrast, the most common lymph node pathologies in HIV-negative patients were nonspecific reactive lymphoid hyperplasia (45%), carcinoma (25%) and Mycobacterial infection (11%). In this group, non-Hodgkin lymphoma and Hodgkin lymphoma constituted 9% and 8%, respectively. There were more cases of high-grade non-Hodgkin lymphoma in the HIV-positive group compared to the HIV-negative group. FNA and lymph node biopsy had excellent agreement with regard to Hodgkin lymphoma (K 0.774, SE 0.07, 95% CI 0.606-0.882, p=0.001), and good agreement with regard to non-Hodgkin lymphoma (K 0.640, SE 0.07, 95% CI 0.472-0.807, p=0.001), carcinoma (K 0.723, SE 0.069, 95% CI 0.528-0.918, p=0.001), and mycobacterial infection (K 0.726, SE 0.07, 95% CI 0.618-0.833, p=0.001). Conclusions The most common lymph node pathologies in CHBAH are malignancies, nonspecific reactive lymphoid hyperplasia, necrotizing granulomatous inflammation and HIV reactive nodes. The distribution of disease differed in HIV-positive patients. Overall, adequate FNA samples of lymph nodes have been found to have good correlation with lymph node biopsy findings in our setting.

Les eaux de surface sont des ressources importantes pour la biosphère et l'anthroposphère. Elles favorisent la préservation des habitats, le développement de la biodiversité et le maintien des services écosystémiques en contrôlant le cycle des nutriments et le carbone à l’échelle mondiale. Elles sont essentielles à la vie quotidienne de l’homme, notamment pour l'irrigation, la consommation d’eau potable, la production hydro-électrique, etc. Par ailleurs, lors des inondations, elles peuvent présenter des dangers pour l'homme, les habitations et les infrastructures. La surveillance des changements dynamiques des eaux de surface a donc un rôle primordial pour guider les choix des gestionnaires dans le processus d’aide à la décision. L’imagerie satellitaire constitue une source de données adaptée permettant de fournir des informations sur les eaux de surface. De nos jours, la télédétection satellitaire a connu une révolution avec le lancement des satellites Sentinel-1 (Radar) et Sentinel-2 (Optique) qui disposent d’une haute fréquence de revisite et d’une résolution spatiale moyenne à élevée. Ces données peuvent fournir des séries temporelles essentielles pour apporter davantage d'informations afin d'améliorer la capacité d'observation des eaux de surface. L’exploitation de telles données massives et multi-sources pose des défis en termes d’extraction de connaissances et de processus de traitement d’images car les chaines de traitement doivent être le plus automatiques possibles. Dans ce contexte, l'objectif de ce travail de thèse est de proposer de nouvelles approches permettant de cartographier l’extension spatiales des eaux de surface et des inondations, en explorant l'utilisation unique et combinée des données Sentinel-1 et Sentinel-2. / Surface waters are important resources for the biosphere and the anthroposphere. Surface waters preserve diverse habitat, support biodiversity and provide ecosystem service by controlling nutrient cycles and global carbon. Surface waters are essential for human's everyday life, such as for irrigation, drinking-water and/or the production of energy (power plants, hydro-electricity). Further, surface waters through flooding can pose hazards to human, settlements and infrastructures. Monitoring the dynamic changes of surface waters is crucial for decision making process and policy. Remote sensing data can provide information on surface waters. Nowadays, satellite remote sensing has gone through a revolution with the launch of the Sentinel-1 SAR data and Sentinel-2 optical data with high revisit time at medium to high spatial resolution. Those data can provide time series and multi-source data which are essential in providing more information to upgrade ability in observing surface water. Analyzing such massive datasets is challenging in terms of knowledge extraction and processing as nearly fully automated processing chains are needed to enable systematic detection of water surfaces.In this context, the objectives of the work are to propose new (e.g. fully automated) approaches for surface water detection and flood extents detection by exploring the single and combined used of Sentinel-1 and Sentinel-2 data.

The European Water Framework Directive (Directive 2000/60/EC) is a mandatory agreement that guides the member states of the European Union in the field of water policy to fulfil the requirements for reaching the aim of the good ecological status of water bodies. In the last years several work ows and methods were developed to determine and evaluate the haracteristics and the status of the water bodies. Due to their area measurements remote sensing methods are a promising approach to constitute a substantial additional value. With increasing availability of optical and radar remote sensing data the development of new methods to extract information from both types of remote sensing data is still in progress. Since most limitations of these data sets do not agree the fusion of both data sets to gain data with higher spectral resolution features the potential to obtain additional information in contrast to the separate processing of the data. Based thereupon this study shall research the potential of multispectral and radar remote sensing data and the potential of their fusion for the assessment of the parameters of water body structure. Due to the medium spatial resolution of the freely available multispectral Sentinel-2 data sets especially the surroundings of the water bodies and their land use are part of this study. SAR data is provided by the Sentinel-1 satellite. Different image fusion methods are tested and the combined products of both data sets are evaluated afterwards. The evaluation of the single data sets and the fused data sets is performed by means of a maximum-likelihood classification and several statistical measurements. The results indicate that the combined use of different remote sensing data sets can have an added value.

No description available.

Southwest Virginia has recently become an emerging focus of activity for La Crosse (LAC) virus, a mosquito-transmitted arbovirus in the California serogroup of Bunyaviruses. In 2005 and 2006, ovitrap surveys were conducted to access the spatiotemporal oviposition activity of LAC virus vectors Aedes triseriatus, Ae. albopictus and Ae. japonicus across a wide region of southwest Virginia. Egg abundance and oviposition patterns of these vectors were significantly different across the three study areas. The primary LAC virus vector, Ae. triseriatus, was collected in the greatest abundance from all three areas, and favored forested habitats. Aedes albopictus was the second most abundant species collected, and was found to favor urban environments. Aedes japonicus also has a preference for urban habitats, and is actively expanding its range throughout southwest Virginia. Dogs were used to determine their efficacy as sentinels for assessing the distribution of LAC virus in southwest Virginia. Canine serum samples were tested using plaque reduction neutralization (PRNT) assays. Of the 436 collected canine serum samples, 21 (4.8%) were positive for LAC virus antibodies. LAC virus seroprevalence was evident in dogs from each study region, including areas where LAC virus human cases and LAC virus positive mosquito isolates have not been reported. As a result, this study provided documentation of horizontal transmission of LAC virus throughout southwest Virginia, demonstrating that dogs make useful sentinels for assessing the distribution of LAC virus in an area. The final objective examined the effects of coinfection with D. immitis microfilariae and LAC virus in three species of Aedes mosquitoes. No significant differences were found between mosquitoes fed dually infected bloodmeals (i.e. D. immitis microfilariae and LAC virus) and those fed bloodmeals containing LAC virus only. A follow-up study found low mosquito midgut penetration rates by D. immitis, despite using biologically significant doses of microfilariae. Failure to demonstrate enhancement of LAC virus in vector mosquitoes suggests that D. immitis does not have a significant impact on LAC virus epidemiology in areas where these organisms co-exist. / Ph. D.

No / Submerged palaeolandscapes can contain pristine underwater heritage. Regular monitoring of these areas is essential to assess and mitigate threats from development including construction, mining, and commercial trawling. While bathymetry alone may be insufficient to detect submerged palaeolandscape features, it can nonetheless recognize previously mapped structures that have a topographic expression. The Sentinel-1 constellation will provide unprecedented access to freely available, high-resolution Synthetic Aperture Radar (SAR) data, acquired systematically and with long-term continuity, and may constitute a cost-effective solution for the monitoring of submerged palaeolandscapes. The article shows the application of a recently developed bathymetric algorithm to Sentinel-1 SAR data over a region of the southern North Sea. Results show general agreement with water depth data obtained from the European Marine Observation and Data Network portal for bathymetry (EMODnet). To assess the support that SAR bathymetry can provide to the analysis of submerged palaeolandscapes, the Sentinel-1-derived water depths were compared to a palaeolandscape map of the same area produced by the North Sea Palaeolandscapes Project (NSPP). Results show a clear correspondence between certain topographic structures identified in the Sentinel-1 water depth map and features interpreted by the NSPP as early Holocene lakes, rivers, and landscape topography.

Glaciers in the western United States, essential freshwater reservoirs, and climate change indicators, are evaluated to understand their present conditions using Sentinel 2A satellite imagery and Random Forest machine learning. Furthermore, this study utilizes MODIS albedo and temperature data, along with Sentinel 5 Precursor, to understand trends and changes in summer glacier albedo within the region, while also investigating the underlying factors influencing glacier albedo, with Mount Rainier as case study. The results of this study reveal that glaciers have lost 236.96 km2 in their area and a corresponding volume loss of 4.9 km3 from the mid-20th century to 2020. Additionally, analysis on the albedo changes of glaciers on Mount Rainier shows a decreasing trend at a rate of 3.29 x 10-6 per day. Further analysis reveals that temperature is the dominant factor affecting the albedo of glaciers in this region with Carbon Monoxide and aerosols following suit.