Last week, we saw how we could represent clustering with a probabilistic model. In this model, called a Gaussian mixture model, we model each datapoint x i as originating from some cluster, with a corresponding cluster label y i distributed according to p(y), and the corresponding distribution for that cluster given by a multivariate Gaussian: p(x|y = k) =

In gas chromatography, the logarithm of the net retention volume of the members of the homologous seriesof the n-alkanes, C~H,~÷ 2 , gives a nearly linear plot asa function of the carbon number z. By designating the logarithmic retention of the n-alkanes as 100 z, the position of a peak can easily be characterized by linear interpolation between two adjacent n-paraffins eluted before and after ...

402 P&T® • July 2006 • Vol. 31 No. 7 Digestive Disease Week is the largest international gathering of physicians, researchers, and academicians in the fields of gastroenterology, hepatology, endoscopy, and gastrointestinal surgery. Jointly sponsored by the American Association for the Study of Liver Diseases, the American Gastroenterological Association, the American Society for Gastrointestina...

Introduction Cecil Alergant's contributions to the specialty were both unique and extensive. He founded a great tradition in 1967 by inaugurating the first university course which culminated in an examination for a Diploma in Venereology awarded by the University of Liverpool. This remains the only Diploma in the specialty awarded by a university in the United Kingdom. Cecil's loyalty and servi...

So far, we discussed clustering algorithms that involve a hard assignment of each datapoint to a cluster, typically based on its proximity to other points in that cluster. However, simply assigning points to the nearest cluster is not always adequate to capture more complex structure. For example, the lecture slides show an example where one cluster is much larger and less dense than another. W...

“As a resident in internal medicine I observed a few jaundiced alcoholic patients who were sent to surgery for obstructive jaundice, but were found to have fatty livers instead. These patients had hyperlipemia, usually only documented as an elevated blood cholesterol concentration. I looked carefully at the hospital records of a series of such patients with lipemia and noted a pattern of abnorm...

Many years ago, between 1963 and 1970, we found that Ca-dependent myocardial contractile energy expenditure (and oxygen requirement), as well as Ca-dependent vascular smooth-muscle activity, can be damped directly with the use of a new family of drugs that in 1966 we designated “calcium antagonists.” These agents inhibit transmembrane Ca supply to the contractile system so that the Ca-dependent...

INTRODUCTION Health professions students interested in future rural practice locations spend a week learning about and investigating all aspects of small town personal, professional and community life. This augments the mainly clinical experience provided by clinical rotations they complete as part of their professional academic training program. METHODS Students from professional programs in...