Dissipative Quasigeostrophic Dynamics under Random Forcing

The quasigeostrophic model is a simplified geophysical fluid model at asymptotically high rotation rate or at small Rossby number. We consider the quasigeostrophic equation with dissipation under random forcing in bounded domains. We show that global unique solutions exist for appropriate initial data. Unlike the deterministic quasigeostrophic equation whose well-posedness is well-known, there seems no rigorous result on global existence and uniqueness of the randomly forced quasigeostrophic equation. Our work provides such a rigorous result on global existence and uniqueness, under very mild conditions.Comment: LaTeX, 15 page

Nonlocal Dynamics of Passive Tracer Dispersion with Random Stopping

We investigate the nonlocal behavior of passive tracer dispersion with random stopping at various sites in fluids. This kind of dispersion processes is modeled by an integral partial differential equation, i.e., an advection-diffusion equation with a memory term. We have shown the exponential decay of the passive tracer concentration, under suitable conditions for the velocity field and the probability distribution of random stopping time.Comment: 7 page

Interpretation and Application of Elements of Differential Geometry and Lie Theory

Basic concepts of differential geometry and Lie theory are introduced. Lie transformation groups are applied to linear systems of differential equations and the problem of describing rigid body orientation. Linear Hamiltonian systems are then treated as a Lie system of differential equations. This theory is applied to a particular Hamiltonian system arising from a problem in control theory, the linear state regulator problem

Effect of delayed acquisition times on Gadolinium-enhanced MRI of the presumably normal canine brain

A delay in imaging following intravenous contrast medium administration has been recommended to reduce misdiagnoses. However, the normal variation of contrast enhancement in dogs following a delay has not been characterized. Contrast enhanced MR imaging of 22 dogs was assessed, in terms of identification of normal anatomic structures, to investigate the variation associated with 10 minute delay between contrast medium administration and imaging. All dogs had a normal brain MR imaging study and unremarkable CSF. Specific ROIs were assessed both objectively, using computer software, and subjectively using three observers. Mean contrast enhancement greater than 10% was seen in the pituitary gland, choroid plexus, meninges, temporal muscle, trigeminal nerve and the trigeminal nerve root. Structures with an active blood-brain-barrier had minimal contrast enhancement (<6%). Enhancing structures had significantly more contrast enhancement at t=1min versus t=10min, except in temporal muscle, the trigeminal nerve and the trigeminal nerve root. Inter-observer agreement was moderate to good in favor of the initial post contrast T1w sequence. The observers found either no difference or poor agreement in identification of the non-vascular structures. Intra-observer agreement was very good with all vascular structures and most non-vascular structures. A degree of meningeal enhancement was a consistent finding. The initial acquisition had higher enhancement characteristics and observer agreement for some structures; however, contrast-to-noise was comparable in the delayed phase or not significantly different. We provide baseline references and suggest that the initial T1w post contrast sequence is preferable but not essential should a delayed post contrast T1w sequence be performed

Exploring the Effects of Team-Based Learning in a Preservice Reading Methods Course

Teacher educators are tasked with preparing preservice teachers with both the content and pedagogical knowledge and skills to teach children to read. In this study we investigated the use of team-based learning (TBL) in a reading methods course as a framework for improving student learning outcomes. TBL is an instructional approach that has been used across a variety of fields in higher education but has only recently made its way into teacher preparation programs. Using mixed methods, we compared TBL to the traditional lecture to explore whether participation in TBL affected preservice elementary teachers’ level of preparation for class, achievement of learning outcomes, and perceptions of TBL. Results showed no statistically significant differences in preparation or learning outcomes. Overall, preservice teachers reported that they liked several TBL components. Further research is required to determine whether TBL has an impact on learning outcomes after a longer period of implementation, over time, and/or on teaching behaviors

Tomography of a High-Purity Narrowband Photon From a Transient Atomic Collective Excitation

We demonstrate the efficient heralded generation of high purity narrow-bandwidth single photons from a transient collective spin excitation in a hot atomic vapour cell. Employing optical homodyne tomography, we fully reconstruct the density matrix of the generated photon and observe a Wigner function reaching the zero value without correcting for any inefficiencies. The narrow bandwidth of the photon produced is accompanied by a high generation rate yielding a high spectral brightness. The source is therefore compatible with atomic-based quantum memories as well as other applications in light-atom interfacing. This work paves the way to preparing and measuring arbitrary superposition states of collective atomic excitations.Comment: Version 2: Fixed typo in bandwidth, Changed fig. 3 to png reduce file size, added 1 reference, expanded several explanation

Studies on the Thermodynamics of Ion Association in Aqueous Solutions

Studies have been made on the association in aqueous solution between divalent transition metal ions and the anions of mono-and di-carboxylic acids. The thesis is divided into four parts. In Part I the association between the nickel ion and the malonate and n-butylmalonate anions has been studied using a cell incorporating a pair of glass electrodes and a pair of silver, silver chloride electrodes. In order to determine the best activity coefficient expression to be used, both systems were studied at low concentration, activity coefficients being calculated from the Davies equation, and at constant ionic strengths of 0.03, 0.05, 0.10, 0.15 and 0.20 M. The stability constants have been extrapolated to zero ionic strength and the thermodynamic constants are compared with those determined at low concentration. Part II deals with the study of the association of the divalent nickel, cobalt and manganese ions with the glycinate and beta-alaninate anions over the temperature range of 0° to 45°C using the cell Hg/Pt/HA, NaOH, MCl2,/AgCl/Ag. Activity coefficients were calculated from the equation for various values of beta. A comparison of the results shows that for low ionic strengths consistent association constants are obtained with 0 ≤ beta ≤ 1. The constants determined with beta = 0.2 have been used in the calculation of the thermodynamic properties. The dissociations of beta-alanine have been measured over the same temperature range and the results are compared with those in the literature. Part III describes a calorimetric determination of the heats of formation of the complexes studied in Part II. The heat of solution of potassium chloride has also been determined in order to calibrate the calorimeter. Part IV consists of a general discussion of the results. The heat and entropy data are discussed in relation to ionic sizes and electronic structure and the entropies of ion-pairs have been calculated

The Beliefs and Practices of Second Grade Teachers Who Implement Independent Reading and Its Effect on Students’ Reading Achievement and Reading Volume

The purpose of the present study was to explore the beliefs and practices of teachers who implement independent reading in their classrooms. Results showed that teachers who implemented independent reading believed in the importance of both the quantity and quality of student reading. The teachers’ practices of independent reading showed students selecting books that were “just-right” for them to read, social experiences around reading, guided practice through reading conferences with the teacher, and setting a purpose for reading through response activities. A nonexperimental comparative design was used to examine the effects of independent reading on reading volume and reading achievement. Results indicated that there were no statistically significant effects between the independent reading group and the no independent reading group for reading achievement or reading volume. Additionally, there was no statistically significant difference in growth of reading achievement between higher and lower readers in the independent reading group