Marcus Märtens

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We develop a new k-means clustering algorithm for data streams of points from a Euclidean space. We call this algorithm StreamKM++. Our algorithm computes a small weighted sample of the data stream and solves the problem on the sample using the k-means++ algorithm of Arthur and Vassilvitskii (SODA '07). To compute the small sample, we propose two new(More)
We develop a new <it>k</it>-means clustering algorithm for data streams of points from a Euclidean space. We call this algorithm StreamKM++. Our algorithm computes a small weighted sample of the data stream and solves the problem on the sample using the <it>k</it>-means++ algorithm of Arthur and Vassilvitskii (SODA '07). To compute(More)
We develop a new k-means clustering algorithm for data streams, which we call StreamKM++. Our algorithm computes a small weighted sample of the data stream and solves the problem on the sample using the k-means++ algorithm [1]. To compute the small sample, we propose two new techniques. First, we use a non-uniform sampling approach similar to the k-means++(More)
Gathering n mobile robots in one single point in the Euclidean plane is a widely studied problem from the area of robot formation problems. Classically, the robots are assumed to have no physical extent, and they are able to share a position with other robots. We drop these assumptions and investigate a similar problem for robots with (a spherical) extent:(More)
A patient is reported with hypertrophic osteoarthropathy of the right leg who developed an osteomyelitis; this appeared to be related to an infected aortic bifurcation prosthesis with increased uptake on leukocyte scan and chronic gas formation at the proximal aortic anastomosis on computed tomography. There have been previous reports of hypertrophic(More)
Gut permeability as measured by the 51Cr-EDTA resorption test was determined in 56 patients with rheumatoid arthritis (RA), 73 patients with spondyloarthropathies (SpA), 18 patients with inflammatory bowel disease (IBD) and 97 controls (42 patients with no inflammatory rheumatic diseases and 55 healthy controls). Gut permeability was found to be increased(More)
Since diffuse idiopathic skeletal hyperostosis (DISH) is frequently difficult to differentiate radiologically from the axial involvement of ankylosing spondylitis and osteoarthrosis, some features of these 3 different diseases were compared. The predominantly horizontal nature of the enthesiophyte in DISH and its right preponderance in the thoracic region(More)
Using the 51Cr-EDTA resorption test, gut permeability was measured in 129 patients with inflammatory joint diseases and in 97 control patients (42 patients with no inflammatory rheumatic disorders taking antiinflammatory medication and 55 healthy controls). Thirty-two patients (30 arthritis and 2 control patients) taking nonsteroidal antiinflammatory drugs(More)
Diffuse idiopathic skeletal hyperostosis (DISH) frequently gives rise to some diagnostic confusion, as it may radiologically mimic ankylosing spondylitis (AS). A patient with features of DISH and AS is described and the literature is reviewed. The diagnostic value of sacroiliac computerized tomography is emphasized. The role of spinal mobility in the(More)
Ileocolonoscopy with biopsy of the colon and terminal ileum was performed prospectively on 12 patients under age 16 with late onset juvenile chronic arthritis (JCA). Inflammatory gut lesions were seen in 9 of these 12 patients; 4 were of the acute type, 5 of the chronic type. Chronic gut inflammation was related to axial inflammatory complaints,(More)