RESUMEN
Many publications make use of opportunistic data, such as citizen science observation data, to infer large-scale properties of species' distributions. However, the few publications that use opportunistic citizen science data to study animal ecology at a habitat level do so without accounting for spatial biases in opportunistic records or using methods that are difficult to generalize. In this study, we explore the biases that exist in opportunistic observations and suggest an approach to correct for them. We first examined the extent of the biases in opportunistic citizen science observations of three wild ungulate species in Norway by comparing them to data from GPS telemetry. We then quantified the extent of the biases by specifying a model of the biases. From the bias model, we sampled available locations within the species' home range. Along with opportunistic observations, we used the corrected availability locations to estimate a resource selection function (RSF). We tested this method with simulations and empirical datasets for the three species. We compared the results of our correction method to RSFs obtained using opportunistic observations without correction and to RSFs using GPS-telemetry data. Finally, we compared habitat suitability maps obtained using each of these models. Opportunistic observations are more affected by human access and visibility than locations derived from GPS telemetry. This has consequences for drawing inferences about species' ecology. Models naïvely using opportunistic observations in habitat-use studies can result in spurious inferences. However, sampling availability locations based on the spatial biases in opportunistic data improves the estimation of the species' RSFs and predicted habitat suitability maps in some cases. This study highlights the challenges and opportunities of using opportunistic observations in habitat-use studies. While our method is not foolproof it is a first step toward unlocking the potential of opportunistic citizen science data for habitat-use studies.
RESUMEN
From 1996 to 2000, high-dose chemotherapy with haematopoietic stem-cell support was used as an adjuvant treatment strategy for management of primary high-risk breast cancer patients with more than five positive nodes. This single institution study included 52 women aged h 56 years with primary operable breast cancer and S 6 tumour-positive axillary lymph nodes. The treatment regimen consisted of at least three initial courses of FEC (5-fluorouracil, epirubicin, cyclophosphamide) followed by high-dose chemotherapy (cyclophosphamide, thiotepa, carboplatin) supported by autologous peripheral blood stem-cell reinfusion. This study focuses on quality control including evaluation of toxicity, supportive therapy and assessment of the stem-cell products. Cytokeratin 19 positive cells were found in the stem-cell product from 3/37 patients. Data regarding organ toxicity were used for evaluation of short- and long-term side effects. Substantial acute toxicity and frequent catheter-related infections were found. Long-term toxicities included reduced lung diffusion capacity (n=36), fatigue (n=14), arthralgia/myalgia (n=10), neurotoxicity (n=9) and memory loss (n=4). However, most toxicities were grade 1-2 and reversible within two years. No treatment-related death occurred. Within a median follow-up of 30 months (range, 11-57), 25% of the patients had relapsed. Recurrence-free survival was 75% and overall survival was 88% three years after the start of treatment. Overall, high-dose chemotherapy was relatively well tolerated, with manageable toxicity and an acceptable requirement of supportive therapy. Until now, high-dose chemotherapy has not proven superior to conventional-dose adjuvant chemotherapy, therefore it is necessary in the future to focus on well-designed randomized studies.
RESUMEN
From 1996 to 2000, high-dose chemotherapy with haematopoietic stem-cell support was used as an adjuvant treatment strategy for management of primary high-risk breast cancer patients with more than five positive nodes. This single institution study included 52 women aged < or = 56 years with primary operable breast cancer and > or = 6 tumour-positive axillary lymph nodes. The treatment regimen consisted of at least three initial courses of FEC (5-fluorouracil, epirubicin, cyclophosphamide) followed by high-dose chemotherapy (cyclophosphamide, thiotepa, carboplatin) supported by autologous peripheral blood stem-cell reinfusion. This study focuses on quality control including evaluation of toxicity, supportive therapy and assessment of the stem-cell products. Cytokeratin 19 positive cells were found in the stem-cell product from 3/37 patients. Data regarding organ toxicity were used for evaluation of short- and long-term side effects. Substantial acute toxicity and frequent catheter-related infections were found. Long-term toxicities included reduced lung diffusion capacity (n = 36), fatigue (n = 14), arthralgia/myalgia (n = 10), neurotoxicity (n = 9) and memory loss (n = 4). However, most toxicities were grade 1-2 and reversible within two years. No treatment-related death occurred. Within a median follow-up of 30 months (range, 11-57), 25% of the patients had relapsed. Recurrence-free survival was 75% and overall survival was 88% three years after the start of treatment. Overall, high-dose chemotherapy was relatively well tolerated, with manageable toxicity and an acceptable requirement of supportive therapy. Until now, high-dose chemotherapy has not proven superior to conventional-dose adjuvant chemotherapy, therefore it is necessary in the future to focus on well-designed randomized studies.
