338 research outputs found

    Combining Exploration and Exploitation in Active Learning

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    This thesis investigates the active learning in the presence of model bias. State of the art approaches advocate combining exploration and exploitation in active learning. However, they suffer from premature exploitation or unnecessary exploration in the later stages of learning. We propose to combine exploration and exploitation in active learning by discarding instances outside a sampling window that is centered around the estimated decision boundary and uniformly draw sample from this window. Initially the window spans the entire feature space and is gradually constricted, where the rate of constriction models the exploration-exploitation tradeoff. The desired effect of this approach (CExp) is that we get an increasing sampling density in informative regions as active learning progresses, resulting in a continuous and natural transition from exploration to exploitation, limiting both premature exploitation and unnecessary exploration. We show that our approach outperforms state of the art on real world multiclass datasets. We also extend our approach to spatial mapping problems where the standard active learning assumption of uniform costs is violated. We show that we can take advantage of \emph{spatial continuity} in the data by geographically partitioning the instances in the sampling window and choosing a single partition (region) for sampling, as opposed to taking a random sample from the entire window, resulting in a novel spatial active learning algorithm that combines exploration and exploitation. We demonstrate that our approach (CExp-Spatial) can generate cost-effective sampling trajectories over baseline sampling methods. Finally, we present the real world problem of mapping benthic habitats where bathymetry derived features are typically not strong enough to discriminate the fine details between classes identified from high-resolution imagery, increasing the possiblity of model bias in active learning. We demonstrate, under such conditions, that CExp outperforms state of the art and that CExp-Spatial can generate more cost-effective sampling trajectories for an Autonomous Underwater Vehicle in contrast to baseline sampling strategies

    MRI-scan: gladhelder nieuwtje

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    Contains fulltext : 24342___.PDF (publisher's version ) (Open Access

    Sister Mary Joseph nodule as a first and only sign of extraovarian carcinoma: a case report and review of the literature.

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    Contains fulltext : 70993.pdf (publisher's version ) (Open Access)Sister Mary Joseph nodule is one of the less well-known signs of intra-abdominal metastatic disease. The primary tumor site is nearly always detected because of specific morphologic and immunohistochemical features of the umbilical tumor. We describe a case of a 74-year-old woman with a Sister Mary Joseph nodule, which appeared most likely to be metastatic from a primary serous papillary ovarian carcinoma based on the histologic examination and the immunohistochemical analysis. Despite an extensive workup, no primary tumor could be detected and therefore we ultimately diagnosed the tumor as an extraovarian carcinoma with primary site at the umbilicus. After a literature search we concluded that a primary adenocarcinoma of the umbilicus is extremely rare and to our knowledge has never been described with both morphologic and immunohistochemical features of a serous ovarian carcinoma

    Pelvic inflammatory disease and ovarian cancer.

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    Item does not contain fulltext1 december 201

    The use of monoclonal antibodies for the treatment of epithelial ovarian cancer (review).

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    Contains fulltext : 70632.pdf (publisher's version ) (Open Access)The prognosis for patients with ovarian cancer is still poor and more effective therapeutic modalities are needed. (Radio)immunotherapy using monoclonal antibodies (Mabs) could be one of these approaches. Here, we review the status of (radio)immunotherapy using Mabs for the treatment of ovarian cancer. The Pubmed database was searched for clinical trials investigating the effect of (radio)immunotherapy in ovarian cancer published until October 1, 2007. Keywords for the search were: ovarian cancer, monoclonal antibodies, CA 125, gp38, HER2, HMFG, MUC1, TAG 72 and VEGF. A total of 44 trials on immunotherapy with unconjugated Mabs, Mab vaccination and (radio)immunotherapy directed towards the antigens CA 125, gp38, HER2, MUC1, TAG 72 or VEGF in patients with ovarian cancer were found, reviewed and discussed. Out of these trials, 23 studied immunotherapy with unconjugated Mabs, 5 vaccination with Mabs and 16 trials studied (radio)immunotherapy. The lack of large randomized prospective trials with Mabs directed to tumor-associated antigens expressed on ovarian cancer cells preclude any firm conclusion on the potential of Mabs use in the treatment of ovarian cancer. Oregovomab, directed against CA 125, and bevacizumab, targeting VEGF, are two unconjugated Mabs closest to clinical introduction for the treatment of ovarian cancer. Vaccination with Mab ACA 125 seems promising but these findings need to be confirmed in controlled randomized trials. Sole RIT should be investigated with the appropriate radionuclide and a Mab with high affinity for the specific tumor-associated antigen in the appropriate patient group to determine whether it may have a therapeutic effect. Additionally, appending (radio)immunotherapy with anti-TAG 72 or anti-MUC1 to other treatment strategies such as chemotherapy could also be a strategy worthwhile investigating. The potential of Mabs to complement current treatment paradigms, is encouraging and may bring a significant improvement to the overall therapeutic outcomes currently being achieved in ovarian cancer

    Improvement of clinical staging in cervical cancer with serum squamous cell carcinoma antigen and CA 125 determinations

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    Contains fulltext : 26054___.PDF (publisher's version ) (Open Access
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