Der Einfluss des metakognitiven Wissens auf die Entwicklung der Mathematikleistung am Beginn der Sekundarstufe I

Metakognitives Wissen, also das Wissen über kognitive Prozesse und ihre Steuerung, ist in der Gedächtnis- und Leseverstehensforschung in einem breiten Altersbereich vom Kindergartenalter bis zum Ende der Sekundarstufe I als wichtiger Prädiktor kognitiver Leistungen etabliert. Im Inhaltsbereich Mathematik deuten punktuelle Befunde zu korrelativen Zusammenhängen sowie die Wirknachweise metakognitiver Trainingsprogramme auf leistungsrelevante Effekte des metakognitiven Wissens hin. Jedoch fehlt nach wie vor systematische Forschung zum Zusammenhang zwischen metakognitivem Wissen über Planung, Überwachung und Regulation mathematischer Lösungsprozesse und der Entwicklung in curricularen mathematischen Kompetenzen. Diese Fragestellung wurde anhand von drei Forschungsfragen in der Sekundarstufe I untersucht: (a) Unterscheiden sich die Schüler der drei Schularten zu Beginn der fünften Jahrgangsstufe im metakognitiven Wissen? (b) Kann das metakognitive Wissen die Mathematikleistung zu einem späteren Zeitpunkt vorhersagen? (c) Trägt das metakognitive Wissen einen eigenen Anteil zur Vorhersage der Mathematikleistung bei, der über den Einfluss anderer allgemeiner und mathematikspezifischer Leistungsdeterminanten hinaus geht? Die Analysen basieren auf der längsschnittlichen Untersuchung einer Stichprobe von 763 nordbayerischen Schülerinnen und Schülern aus Gymnasien, Realschulen und Hauptschulen. Neben der Mathematikleistung am Beginn und am Ende der fünften Jahrgangsstufe und dem metakognitiven Wissen wurden als Prädiktoren mathematischer Leistungen allgemeine (Intelligenz und soziale Herkunft) sowie mathematikspezifische Schülermerkmale (Rechenfertigkeiten, mathematisches Selbstkonzept und mathematisches Interesse) erhoben. Die Auswertungen erbrachten bedeutsame Schulartunterschiede im metakognitiven Wissen. Das metakognitive Wissen leistet darüber hinaus auch unter Kontrolle der Vorwissensunterschiede und weiterer allgemeiner und spezifischer Leistungsdeterminanten einen bedeutsamen Beitrag in der Vorhersage der Mathematikleistung am Ende der fünften Jahrgangsstufe. Diese Befunde werden als Nachweis für die substanzielle Bedeutung des metakognitiven Wissens für Ausprägung und Entwicklung mathematischer Kompetenzen am Beginn der Sekundarstufe I interpretiert.Metacognitive knowledge, that is the knowledge about cognitive processes and their regulation is established in memory and reading comprehension research as an important predictor of cognitive achievement. ln mathematics some correlational findings and the effects of metacognitive trainings point to the predictive account of metacognitive knowledge in the prediction of achievement. However, there is no systematic research on the relations between metacognitive knowledge on planning, monitoring and regulation processes in the solution of mathematical problems and the development of curricular mathematical achievement. To explore the relation between metacognitive knowledge and achievement in secondary school three research questions were examined: (a) Are there differences in metacognitive knowledge between the students allocated to the three tracks of German educational system? (b) Does metacognitive knowledge predict mathematics achievement? (c) Does metacognitive knowledge show a unique predictive influence even when other general and specific predictors of mathematics achievement are controlled? Two measurement points at the beginning and at the end of Grade 5 were analyzed. The sample consisted of N=763 students from northern Bavaria on three tracks (academic track, intermediate track and vocational track). Mathematics achievement was assessed at both measurement points. Metacognitive knowledge as well as general (intelligence, socio-economic status) and specific (computation skills, mathematical self-concept and mathematical interest) predictors of achievement were assessed at the first measurement point. Students attending the three tracks differed in metacognitive knowledge. Additionally, metacognitive knowledge predicted mathematics achievement at T2. This predictive influence remained significant even under control for prior knowledge as well as general and the specific determinants of mathematics achievement. The findings show the substantial importance of metacognitive knowledge on mathematics achievement and on development of mathematics achievement at the beginning of secondary school

Penguin decays of B mesons

Penguin, or loop, decays of B mesons induce effective flavor-changing neutral currents, which are forbidden at tree level in the Standard Model. These decays give special insight into the CKM matrix and are sensitive to non-standard model effects. In this review, we give a historical and theoretical introduction to penguins and a description of the various types of penguin processes: electromagnetic, electroweak, and gluonic. We review the experimental searches for penguin decays, including the measurements of the electromagnetic penguins b -> s gamma and B -> K* gamma and gluonic penguins B -> K pi, B+ -> omega K+ and B -> eta' K, and their implications for the Standard Model and New Physics. We conclude by exploring the future prospects for penguin physics.Comment: 49 pages, LATEX, 30 embedded figures, submitted to Annual Reviews of Nuclear and Particle Scienc

The sensitivity of the zero position of the forward--backward asymmetry to new physics effects in the B -> K^\ast \mu^+ \mu^- decay

Starting with the most general effective Hamiltonian comprising scalar and vector operators beyond the standard model, we discuss the impact of various operators on the zero of the forward--backward asymmetry in the dileptonic B decay B -> K^\ast \mu^+ \mu^-. We find that, zero of the asymmetry is highly sensitive to the sign and size of the vector--vector operators and opposite chirality counterparts of the usual operators. The scalar--scalar four--fermion operators, on the other hand, have mild effect on the zero of the asymmetry. Our results are expected to be checked in the near future experiments.Comment: 16 pp, 6 ps fig

Expression of HIWI in human esophageal squamous cell carcinoma is significantly associated with poorer prognosis

<p>Abstract</p> <p>Background</p> <p>HIWI, the human homologue of Piwi family, is present in CD34⁺hematopoietic stem cells and germ cells, but not in well-differentiated cell populations, indicating that HIWI may play an impotent role in determining or maintaining stemness of these cells. That HIWI expression has been detected in several type tumours may suggest its association with clinical outcome in cancer patients.</p> <p>Methods</p> <p>With the methods of real-time PCR, western blot, immunocytochemistry and immunohistochemistry, the expression of HIWI in three esophageal squamous cancer cell lines KYSE70, KYSE140 and KYSE450 has been characterized. Then, we investigated HIWI expression in a series of 153 esophageal squamous cell carcinomas using immunohistochemistry and explored its association with clinicopathological features.</p> <p>Results</p> <p>The expression of HIWI was observed in tumour cell nuclei or/and cytoplasm in 137 (89.5%) cases, 16 (10.5%) cases were negative in both nuclei and cytoplasm. 86 (56.2%) were strongly positive in cytoplasm, while 49 (32.0%) were strongly positive in nuclei. The expression level of HIWI in cytoplasm of esophageal cancer cells was significantly associated with histological grade (<it>P </it>= 0.011), T stage (<it>P </it>= 0.035), and clinic outcome (<it>P </it>< 0.001), while there was no correlation between the nuclear HIWI expression and clinicopathological features.</p> <p>Conclusion</p> <p>The expression of HIWI in the cytoplasm of esophageal cancer cells is significantly associated with higher histological grade, clinical stage and poorer clinical outcome, indicating its possible involvement in cancer development.</p

Measurement of the Inclusive Semi-electronic D0D^0 Branching Fraction

Using the angular correlation between the $\pi^+$ emitted in a $D^{*+} \rightarrow D^0 \pi^+$ decay and the $e^+$ emitted in the subsequent $D^0 \rightarrow Xe^+\nu$ decay, we have measured the branching fraction for the inclusive semi-electronic decay of the $D^0$ meson to be: {\cal B}(D^0 \rightarrow X e^+ \nu) = [6.64 \pm 0.18 (stat.) \pm 0.29 (syst.)] \%. The result is based on 1.7 fb$^{-1}$ of $e^+e^-$ collisions recorded by the CLEO II detector located at the Cornell Electron Storage Ring (CESR). Combining the analysis presented in this paper with previous CLEO results we find, \frac{{\cal B} (D^0 \rightarrow X e^+ \nu)} {{\cal B} (D^0 \rightarrow K^- \pi^+)} = 1.684 \pm 0.056 (stat.) \pm 0.093(syst.) and \frac{{\cal B}(D\rightarrow K^-e^+\nu)} {{\cal B}(D\rightarrow Xe^+\nu)} = 0.581 \pm 0.023 (stat.) \pm 0.028(syst.). The difference between the inclusive rate and the sum of the measured exclusive branching fractions (measured at CLEO and other experiments) is $(3.3 \pm 7.2) \%$ of the inclusive rate.Comment: Latex file, 33pages, 4 figures Submitted to PR

Precision Measurement of the Ds∗+−Ds+D_s^{*+}- D_s^+ Mass Difference

We have measured the vector-pseudoscalar mass splitting $M(D_s^{*+})-M(D_s^+) = 144.22\pm 0.47\pm 0.37 MeV$, significantly more precise than the previous world average. We minimize the systematic errors by also measuring the vector-pseudoscalar mass difference $M(D^{*0})-M(D^0)$ using the radiative decay $D^{*0}\rightarrow D^0\gamma$, obtaining $[M(D_s^{*+})-M(D_s^+)]-[M(D^{*0})-M(D^0)] = 2.09\pm 0.47\pm 0.37 MeV$. This is then combined with our previous high-precision measurement of $M(D^{*0})-M(D^0)$, which used the decay $D^{*0}\rightarrow D^0\pi^0$. We also measure the mass difference $M(D_s^+)-M(D^+)=99.5\pm 0.6\pm 0.3$ MeV, using the $\phi\pi^+$ decay modes of the $D_s^+$ and $D^+$ mesons.Comment: 18 pages uuencoded compressed postscript (process with uudecode then gunzip). hardcopies with figures can be obtained by sending mail to: [email protected]

Measurements of the Ratios B(Ds+→ηℓ+ν)/B(Ds+→ϕℓ+ν){\cal B}(D_s^+\to \eta\ell^+\nu)/{\cal B}(D_s^+\to \phi\ell^+\nu) and B(Ds+→η′ℓ+ν)/B(Ds+→ϕℓ+ν){\cal B}(D_s^+\to \eta'\ell^+\nu)/{\cal B}(D_s^+\to \phi\ell^+\nu)

Using the CLEO~II detector we measure ${\cal B}(D_s^+\to \eta e^+\nu)/{\cal B}(D_s^+\to \phi e^+\nu) =1.24\pm0.12\pm0.15$, ${\cal B}(D_s^+\to \eta' e^+\nu)/{\cal B}(D_s^+\to \phi e^+\nu) =0.43\pm0.11\pm0.07$ and ${\cal B}(D_s^+\to \eta' e^+\nu)/{\cal B}(D_s^+\to \eta e^+\nu) =0.35\pm0.09\pm0.07$. We find the vector to pseudoscalar ratio, ${\cal B}(D_s^+\to \phi e^+\nu)/{\cal B}(D_s^+\to (\eta+\eta') e^+\nu) =0.60\pm0.06\pm0.06$, which is similar to the ratio found in non strange $D$ decays.Comment: 11 page uuencoded postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Determination of the Michel Parameters and the tau Neutrino Helicity in tau Decay

Using the CLEO II detector at the $e^+e^-$ storage ring CESR, we have determined the Michel parameters $\rho$, $\xi$, and $\delta$ in $\tau^\mp \to l^\mp\nu\bar{\nu}$ decay as well as the tau neutrino helicity parameter $h_{\nu_\tau}$ in $\tau^\mp \to \pi^\mp\pi^0\nu$ decay. From a data sample of $3.02\times 10^6$ tau pairs produced at $\sqrt{s}=10.6 GeV$, using events of the topology $e^+e^- \to \tau^+\tau^- \to (l^\pm\nu\bar{\nu}) (\pi^\mp\pi^0\nu)$ and $e^+e^- \to \tau^+\tau^- \to (\pi^\pm\pi^0\bar{\nu}) (\pi^\mp\pi^0\nu)$, and the determined sign of $h_{\nu_\tau}$, the combined result of the three samples is: $\rho = 0.747\pm 0.010\pm 0.006$, $\xi = 1.007\pm 0.040\pm 0.015$, $\xi\delta = 0.745\pm 0.026\pm 0.009$, and $h_{\nu_\tau} = -0.995\pm 0.010\pm 0.003$. The results are in agreement with the Standard Model V-A interaction.Comment: 18 page postscript file, postscript file also available through http://w4.lns.cornell.edu/public/CLN

Observation of the Dynamic Beta Effect at CESR with CLEO

Using the silicon strip detector of the CLEO experiment operating at the Cornell Electron-positron Storage Ring (CESR), we have observed that the horizontal size of the luminous region decreases in the presence of the beam-beam interaction from what is expected without the beam-beam interaction. The dependence on the bunch current agrees with the prediction of the dynamic beta effect. This is the first direct observation of the effect.Comment: 9 page uuencoded postscript file, postscritp file also available through http://w4.lns.cornell.edu/public/CLNS, submitted to Phys. Rev.

Further Search for the Two-Photon Production of the Glueball Candidate fJ(2220)f_{J}(2220)

The CLEOII detector at the Cornell e+ e- storage ring CESR has been used to search for the two-photon production of the $f_J(2220)$ decaying into pi+ pi-. No evidence for a signal is found in data corresponding to an integrated luminosity of 4.77/fb and a 95% CL upper limit on $\Gamma_{two-photon} * BR{pi+ pi-}$ of 2.5 eV is set. If this result is combined with the BES Collaboration's measurement of $f_J(2220) -> pi+ pi-$ in radiative $J/\psi$ decay, a 95% CL lower limit on the stickiness of the $f_J(2220)$ of 73 is obtained. If the recent CLEO result for \Gamma_{two-photon} * BR{\K_S K_S} is combined with the present result, the stickiness of the $f_J(2220)$ is found to be larger than 102 at the 95% CL. These results for the stickiness (the ratio of the probabilities for two-gluon coupling and two-photon coupling) provide further support for a substantial neutral parton content in the $f_J(2220)$.Comment: 8 pages, postscript file also available through http://w4.lns.cornell.edu/public/CLN