Spectroscopy, Equation Of State And Monopole Percolation In Lattice QED With Two Flavors

Non-compact lattice QED with two flavors of light dynamical quarks is simulated on $16^4$ lattices, and the chiral condensate, monopole density and susceptibility and the meson masses are measured. Data from relatively high statistics runs at relatively small bare fermion masses of 0.005, 0.01, 0.02 and 0.03 (lattice units) are presented. Three independent methods of data analysis indicate that the critical point occurs at $\beta =0.225(5)$ and that the monopole condensation and chiral symmetry breaking transitions are coincident. The monopole condensation data satisfies finite size scaling hypotheses with critical indices compatible with four dimensional percolation. The best chiral equation of state fit produces critical exponents ($\delta=2.31$, $\beta_{mag}=0.763$) which deviate significantly from mean field expectations. Data for the ratio of the sigma to pion masses produces an estimate of the critical index $\delta$ in good agreement with chiral condensate measurements. In the strong coupling phase the ratio of the meson masses are $M_\sigma^2/M_\rho^2\approx 0.35$, $M_{A_1}^2/M_\rho^2\approx 1.4$ and $M_\pi^2/M_\rho^2\approx 0.0$, while on the weak coupling side of the transition $M_\pi^2/M_\rho^2\approx 1.0$, $M_{A_1}^2/M_\rho^2\approx 1.0$, indicating the restoration of chiral symmetry.\footnote{\,^{}}{August 1992}Comment: 21 pages, 24 figures (not included

An Ultrasonic Measurement System for the Precise Determination of the Elastic Moduli of Single Crystals

The measurement of the ultrasonic wave velocities in a sufficient number of known directions in a single crystal makes possible the direct computation of the elastic moduli of the crystal. For specimens having linear dimensions on the order of 2 to 3 mm, phase comparison techniques were found useful. The equipment described is based on the technique developed by McSkimin. The measurement system is actually a type of acoustic interferometer adapted to small solid specimens, and it requires specialized electronic equipment which cannot be purchased off the shelf. (auth

Science Classroom Inquiry (SCI) simulations: A novel method to scaffold science learning

Science education is progressively more focused on employing inquiry-based learning methods in the classroom and increasing scientific literacy among students. However, due to time and resource constraints, many classroom science activities and laboratory experiments focus on simple inquiry, with a step-by-step approach to reach predetermined outcomes. The science classroom inquiry (SCI) simulations were designed to give students real life, authentic science experiences within the confines of a typical classroom. The SCI simulations allow students to engage with a science problem in a meaningful, inquiry-based manner. Three discrete SCI simulations were created as website applications for use with middle school and high school students. For each simulation, students were tasked with solving a scientific problem through investigation and hypothesis testing. After completion of the simulation, 67% of students reported a change in how they perceived authentic science practices, specifically related to the complex and dynamic nature of scientific research and how scientists approach problems. Moreover, 80% of the students who did not report a change in how they viewed the practice of science indicated that the simulation confirmed or strengthened their prior understanding. Additionally, we found a statistically significant positive correlation between students' self-reported changes in understanding of authentic science practices and the degree to which each simulation benefitted learning. Since SCI simulations were effective in promoting both student learning and student understanding of authentic science practices with both middle and high school students, we propose that SCI simulations are a valuable and versatile technology that can be used to educate and inspire a wide range of science students on the real-world complexities inherent in scientific study

Ignition and Extinction of Autothermal Reactors at Periodic Operation

Material and temp. instabilities in autothermal reactors, e.g. catalyst temp. instabilities and steep radial and axial temp. profiles, and difficulty in isolation of intermediate products, are resolved by periodic operation of the reactor. Using the oxidn. of propylene over Pt gauze as an example, it was shown that operation at high frequency within the temp.-conversion hysteresis allows the reactor to operate in a pseudostationary mode at one of the stable operating points. Increasing the mass capacity or the periodic frequency lowers the concn. amplitude. The cycle amplitudes are mainly detd. by the heat capacity of the system

The Block Spin Renormalization Group Approach and Two-Dimensional Quantum Gravity

A block spin renormalization group approach is proposed for the dynamical triangulation formulation of two-dimensional quantum gravity. The idea is to update link flips on the block lattice in response to link flips on the original lattice. Just as the connectivity of the original lattice is meant to be a lattice representation of the metric, the block links are determined in such a way that the connectivity of the block lattice represents a block metric. As an illustration, this approach is applied to the Ising model coupled to two-dimensional quantum gravity. The correct critical coupling is reproduced, but the critical exponent is obscured by unusually large finite size effects.Comment: 10 page

Linking cortical visual processing to viewing behavior using fMRI

One characteristic of natural visual behavior in humans is the frequent shifting of eye position. It has been argued that the characteristics of these eye movements can be used to distinguish between distinct modes of visual processing (Unema et al., 2005). These viewing modes would be distinguishable on the basis of the eye-movement parameters fixation duration and saccade amplitude and have been hypothesized to reflect the differential involvement of dorsal and ventral systems in saccade planning and information processing. According to this hypothesis, on the one hand, while in a “pre-attentive” or ambient mode, primarily scanning eye movements are made; in this mode fixation are relatively brief and saccades tends to be relatively large. On the other hand, in “attentive” focal mode, fixations last longer and saccades are relatively small, and result in viewing behavior which could be described as detailed inspection. Thus far, no neuroscientific basis exists to support the idea that such distinct viewing modes are indeed linked to processing in distinct cortical regions. Here, we used fixation-based event-related (FIBER) fMRI in combination with independent component analysis (ICA) to investigate the neural correlates of these viewing modes. While we find robust eye-movement-related activations, our results do not support the theory that the above mentioned viewing modes modulate dorsal and ventral processing. Instead, further analyses revealed that eye-movement characteristics such as saccade amplitude and fixation duration did differentially modulate activity in three clusters in early, ventromedial and ventrolateral visual cortex. In summary, we conclude that evaluating viewing behavior is crucial for unraveling cortical processing in natural vision

Adoption, Anpassung oder Abkehr? - Eine Studie zur Nutzung von kollaborativen Web 2.0-Anwendungen durch Studierende

1 EINLEITUNG Nachdem in den vergangenen Jahren die Bedeutung von Web 2.0-Anwendungen neben dem privaten vor allem auch für den unternehmerischen Bereich untersucht wurde [18], werden seit einiger Zeit auch Einsatzmöglichkeiten in Forschung und Lehre berücksichtigt. Wagner und Schroeder zufolge ermöglicht die Nutzung von Web 2.0-Anwendungen die gemeinsame Schaffung von Inhalten im Internet, die häufigen und unvorhergesehenen Änderungen unterliegen [24]. Viele dieser Anwendungen sind hedonistisch [10] und im privaten Internetnutzungsverhalten von Studenten weit verbreitet [27]. Bereits 2009 hatten Kane und Fichman gefordert, die Möglichkeiten, die die neuen webbasierten Technologien als IT-basierte Kooperationswerkzeuge für den Umgang von Studierenden, Lehrenden und Forschern unter- und miteinander bieten, stärker zu untersuchen [14]. Erste Studien haben sich seitdem mit dem studentischen Arbeitsalltag, in dem Web 2.0 eingesetzt wird, um Kursinhalte unter Kommilitonen zu besprechen und zu verarbeiten [17] oder um gemeinschaftliches Lernen besser zu gestalten [15,16] beschäftigt. Weitere Untersuchungen widmen sich sozialpsychologischen Aspekten, wie z.B. der Frage, wie sich Studierende durch Web 2.0 schneller an das Universitätsleben gewöhnen können [4] oder welche Rolle soziale Netzwerkseiten, wie z.B. Facebook, bei der Formung der studentischen Identität spielen [22]. Die Frage, wie Unterrichtende Web 2.0-Anwendungen nutzen können, um ihre Lehrinhalte zu unterstützen, wurde ebenfalls adressiert [7], wobei insbesondere die Anpassung bestehender Anwendungen auf Unterrichtsbedürfnisse im Mittelpunkt stand [9]. [...

An Effective Model for Crumpling in Two Dimensions?

We investigate the crumpling transition for a dynamically triangulated random surface embedded in two dimensions using an effective model in which the disordering effect of the $X$ variables on the correlations of the normals is replaced by a long-range ``antiferromagnetic'' term. We compare the results from a Monte Carlo simulation with those obtained for the standard action which retains the $X$'s and discuss the nature of the phase transition.Comment: 5 page

Cortical Tonotopic Map Changes in Humans Are Larger in Hearing Loss Than in Additional Tinnitus

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