In both the United States and Europe, concerns have been raised about whether preservice and in-service training succeeds in equipping teachers with the professional knowledge they need to deliver consistently high-quality instruction. This article investigates the significance of teachers' content knowledge and pedagogical content knowledge for high-quality instruction and student progress in secondary-level mathematics. It reports findings from a 1-year study conducted in Germany with a representative sample of Grade 10 classes and their mathematics teachers. Teachers' pedagogical content knowledge was theoretically and empirically distinguishable from their content knowledge. Multilevel structural equation models revealed a substantial positive effect of pedagogical content knowledge on students' learning gains that was mediated by the provision of cognitive activation and individual learning support. American Educational Research Journal March 2010, Vol. 47, No. 1, pp. 133-180 DOI: 10.3102/0002831209345157 Ó 2010 AERA. http://aerj.aera.netat Max Planck Ins on July 27, 2011 http://aerj.aera.net Downloaded from KEYWORDS: teacher knowledge, teacher education, mathematics, instruction, cognitive activation, hierarchical modeling with latent variables S ince Lee Shulman's presidential address at the 1985 American Educational Research Association meeting-in which Shulman went beyond the generic perspective of educational psychology, emphasizing the importance of domain-specific processes of learning and instruction-educational research JÜ RGEN BAUMERT is a co-director at Max Planck Institute for Human Development, Center for Educational Research, Lentzeallee 94, 14195 Berlin, Germany; e-mail: sekbaumert@mpib-berlin.mpg.de. His research interests include research in teaching and learning, cultural comparisons, large-scale assessment, and cognitive and motivational development in adolescence. MAREIKE KUNTER is a research scientist at Max Planck Institute for Human Development, e-mail: kunter@mpib-berlin.mpg.de. Her research interests include teacher research, motivational processes in the classroom, and assessment of instructional processes. WERNER BLUM is a professor of mathematics education at University of Kassel, e-mail: blum@mathematik.uni-kassel.de. His research interests include empirical research on instructional quality in mathematics, national and international comparison studies in mathematics, approaches to application, modeling, and proofs in mathematics instruction. MARTIN BRUNNER is an associate professor at University of Luxembourg, e-mail: martin.brunner@uni.lu. His research interests include research on cognitive abilities, achievement, and achievement motivation by means of modern measurement models. THAMAR VOSS is a predoctoral research fellow at Max Planck Institute for Human Development, e-mail: voss@mpib-berlin.mpg.de. Her research interests include research on instruction and learning, teacher research, and teacher beliefs. ALEXANDER JORDAN is an academic staff member at University of Biel...

Drawing on the work of L. S. Shulman (1986), the authors present a conceptualization of the pedagogical content knowledge and content knowledge of secondary-level mathematics teachers. They describe the theory-based construction of tests to assess these knowledge categories and the implementation of these tests in a sample of German mathematics teachers (N ϭ 198). Analyses investigate whether pedagogical content knowledge and content knowledge can be distinguished empirically, and whether the mean level of knowledge and the degree of connectedness between the two knowledge categories depends on mathematical expertise. Findings show that mathematics teachers with an in-depth mathematical training (i.e., teachers qualified to teach at the academic-track Gymnasium) outscore teachers from other school types on both knowledge categories and exhibit a higher degree of cognitive connectedness between the two knowledge categories.

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Pigment gallstones constitute up to 25% of all gallstones in the West1 and in non-Western populations they are probably the predominant type of gallstone^.^ In contrast to cholesterol gallstones that are comprised chiefly (usually more than 50% by weight) of cholesterol monoh~d r a t e ,~-~ a normal constituent of bile, pigment gallstones are complex mixtures of several insoluble calcium salts that are not normal constituents of bile. Principal constituents of pigment gallstones are the calcium salts of unconjugated b i l i r~b i n ,~ ~a r b o n a t e ,~.~ p h o~p h a t e ,~,~ and palmitate and ~t e a r a t e .~. '~ In addition, pigment gallstones may contain variable amounts of crystalline cholesterol monohydratell (ranging from 0 to 35% by weight), free fatty acids,12J3 free bile acids,14 and some biliary lecithin.12.13 Insoluble calcium salts only precipitate from bile that is supersaturated with respect to the equilibrium solubilities of the products of ionized calcium and the free anions.15-l9 In contrast to cholesterol solubilities, the solubilities of these calcium salts in bile are exquisitely pH ~e n s i t i v e .~~. '~.~~ A rich mucin glycoprotein matrix, secreted by the biliary tree, is invariably present in pigment g a l l~t o n e s .~l -~~ Because of assay difficulties, this matrix was known previously as "unmeasured residue. ' 72.8 Mucin and, possibly, other cosecreted glycoproteins apparently provide the organic cement for accretion of the heterogeneous mixture of calcium salts to produce mature pigment stones.21In this article we will classify and briefly review the physical and chemical characteristics of pigment gallstones. We will discuss the physical-chemistry of pigment stone biles as well as the physical-chemical conditions necessary for precipitation of each pigment stone component in bile. We will attempt to define putative factors in the pathogenesis of calcium-anion supersaturated biles and will discuss factors leading to nucleation. We will conclude with pointers for future research on possible causes and prevention of pigment gallstones.

This guideline provides evidence-based key recommendations for the prevention, diagnosis and therapy of gallstones and upgrades the 2007 version. The guideline was developed by an interdisciplinary team of gastroenterologists and surgeons, and patient support groups under the auspice of the German Society for Gastroenterology and Metabolic Diseases and the German Society for General Surgery and Surgery of the Alimentary Tract. The guideline used structural S3 consensus-based methodology and includes statements on clinical practice, medical education, prevention, quality assurance, outcome analysis, and integration of outpatient and inpatient care for patients with gallstone diseases.

In patients with PSC, MRCP is a highly sensitive method and its diagnostic accuracy is comparable to that of ERCP.

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