Helping Provisionally Licensed Middle School Science Teachers

The New Science Teachers\u27 Support Network is a National Science Foundation-funded project that provides a multifaceted support system to provisionally licensed middle and high school science teachers.The teachers in this project were all hired to teach science, and had science degrees, but had little or no education coursework or background. Research is being conducted on the effectiveness of the support system we employed for these teachers, particularly on the factors that characterize the practice of new teachers, and on factors that lead to teacher success and teacher retention. In this paper, we describe the design of the study and the results from the one-year pilot study. We focus upon our observations and experiences with the middle school teachers in the group of participants; and, we close with preliminary recommendations for supporting provisionally licensed science teachers so they have the best chance of being successful and staying in the teaching profession

Increased surface flashover voltage in microfabricated devices

With the demand for improved performance in microfabricated devices, the necessity to apply greater electric fields and voltages becomes evident. When operating in vacuum, the voltage is typically limited by surface flashover forming along the surface of a dielectric. By modifying the fabrication process we have discovered it is possible to more than double the flashover voltage. Our finding has significant impact on the realization of next-generation micro- and nano-fabricated devices and for the fabrication of on-chip ion trap arrays for the realization of scalable ion quantum technology

Modeling for Active Control of Combustion and Thermally Driven Oscillations

Organized oscillations excited and sustained by high densities of energy release in combustion chambers have long caused serious problems in development of propulsion systems. The amplitudes often become sufficiently large to cause unacceptable structural vibrations. Because the oscillations are self-excited, they reach limiting amplitudes (limit cycles) only because of the action of nonlinear processes. Traditionally, satisfactory behavior has been achieved through a combination of trial-and-error design and testing, with control always involving passive means: geometrical modifications, changes of propellant composition, or devices to enhance dissipation of acoustic energy. Active control has been applied only to small-scale laboratory devices, but the limited success suggests the possibility of serious applications to full-scale propulsion systems. Realization of that potential rests on further experimental work, combined with deeper understanding of the mechanisms causing the oscillations and of the physical behavior of the systems. Effective design of active control systems will require faithful modeling of the relevant processes over broad frequency ranges covering the spectra of natural modes. This paper will cover the general character of the linear and nonlinear behavior of combustion systems, with special attention to acoustics and the mechanisms of excitation. The discussion is intended to supplement the paper by Doyle et al. concerned primarily with controls issues and the observed behavior of simple laboratory devices

Longitudinal Mode Combustion Instabilities in a Dump Combustor

The mechanism by which longitudinal modes of a dump combustor are excited has been investigated. The unsteady combustion is a result of the shedding of large scale vortical structures from the flameholder. Driving and damping as determined by Rayleigh's criterion were investigated by using the cross-spectrum and phase of the fluctuating pressure and radiation intensity signals at various locations in the combustor. Thus, the excitation of a particular mode was found to depend on the pressure mode shape and the magnitude and phase of the velocity fluctuation at the flameholder. Fluid mechanical mixing and the chemical reaction rate of the fuel also effect the distribution of heat release and hence the locations of driving and damping. Finally, a mechanism for existence of the limit cycle is discussed

Electron, ion and neutral temperatures at the magnetic equator

Electron density and electron, ion, and neutral temperature profiles at magnetic equato

Mol-CycleGAN - a generative model for molecular optimization

Designing a molecule with desired properties is one of the biggest challenges in drug development, as it requires optimization of chemical compound structures with respect to many complex properties. To augment the compound design process we introduce Mol-CycleGAN - a CycleGAN-based model that generates optimized compounds with high structural similarity to the original ones. Namely, given a molecule our model generates a structurally similar one with an optimized value of the considered property. We evaluate the performance of the model on selected optimization objectives related to structural properties (presence of halogen groups, number of aromatic rings) and to a physicochemical property (penalized logP). In the task of optimization of penalized logP of drug-like molecules our model significantly outperforms previous results

Quasi-bound states in continuum

We report the prediction of quasi-bound states (resonant states with very long lifetimes) that occur in the eigenvalue continuum of propagating states for a wide region of parameter space. These quasi-bound states are generated in a quantum wire with two channels and an adatom, when the energy bands of the two channels overlap. A would-be bound state that lays just below the upper energy band is slightly destabilized by the lower energy band and thereby becomes a resonant state with a very long lifetime (a second QBIC lays above the lower energy band).Comment: 4 pages, 4figures, 1 tabl