Gateways to the Principalship: State Power to Improve the Quality of School Leaders

Examines weaknesses in state policies with respect to principal preparation program approval and licensure requirements and highlights leading states and lagging states in efforts to raise preparation and certification standards. Makes recommendations

A further study of elastic foundation models

Response expressions for elastic foundation model

Total synthesis of the baulamycins, The

2019 Fall.Includes bibliographical references.Described herein are the total syntheses of the antibiotic polyketides baulamycin A and baulamycin B. A synthesis giving rise to much of the baulamycins' initially-proposed structures is also described

The diction of realism, as illustrated in "Mandeville's Travels," "Pilgrim's Progress," and "Robinson Crusoe"

Thesis (M.A.)--Boston Universit

Cu-Au type orderings in the staggered quadrupolar region of the fcc Blume Emery Griffiths model

The spin-1 Ising (BEG) model has been simulated using a cellular automaton (CA) algorithm improved from the Creutz cellular automaton (CCA) for a face-centered cubic (fcc) lattice. The ground state diagram ($k$, $d$) of the fcc BEG model has ferromagnetic ($F$), quadrupolar ($Q$) and staggered quadrupolar ($SQ$) ordering regions. The simulations have been made in the staggered quadrupolar region for the parameter values in the intervals $-24\leq d=D/J<0$ and $-3\leq k=K/J\leq 0$ . The phase diagrams on the ($kT_{C}/J$, $d$) and the ($kT_{C}/J$, $k$) planes have been obtained through $k=-3$ and $d=-4$ lines, respectively. The staggered quadrupolar ordering region separates into five ordering regions ($A_{3}B(a)$, $A_{3}B(f)$, $AB$ (type-I), $AB$(type-II) and $AB_{3}(f)$) which have the different stoichiometric Cu-Au type structures.Comment: 24 pages, 11 figure

Estimation of Spectral Power Laws in Time-Uncertain Series of Data with Application to the GISP2 δ18δ^{18}O Record

Errors in the timing assigned to observations degrade estimates of the power spectrum in a complicated and nonlocal fashion. It is clear that timing errors will smear concentrations of spectral energy across a wide band of frequencies, leading to uncertainties in the analysis of spectral peaks. Less understood is the influence of timing errors upon the background continuum. We find that power law distributions of spectral energy are largely insensitive to errors in timing at frequencies much smaller than the Nyquist frequency, though timing errors do increase the uncertainty associated with estimates of power law scaling exponents. These results are illustrated analytically and through Monte Carlo simulation and are applied in the context of evaluating the power law behavior of oxygen isotopes obtained from Greenland ice cores. Age errors in layer counted ice cores are modeled as a discrete and monotonic random walk that includes the possibility of biases toward under- or overcounting. The δ$^{18}O_{ice}$ record from the Greenland Ice Sheet Project 2 is found to follow a power law of $1.40 \pm 0.19$ for periods between 0.7 and 50 ky, and equivalent results are also obtained for other Greenland ice cores.Engineering and Applied Science

Effects of large-scale topography on abyssal circulation

Two models are employed to study the effect of topographically induced planetary islands (i.e. closed contours of potential vorticity) on the abyssal circulation of an ocean basin. The first is a steady state calculation using a 1½ layer model of the abyssal ocean forced by a uniform upwelling. Planetary geostrophic dynamics yield a characteristic equation in which the inverse potential vorticity serves as a streamfunction for the characteristic velocity field. Aside from warping the classic Stommel-Arons flow in the immediate vicinity of the planetary island, the topography introduces two new elements to the zonal flow west of the topography. The first of these is a system of two zonal jets, flowing in opposite directions and centered on the separatrix contour. The second is an acceleration (or retardation) of the zonal flow (with respect to the classic flat-bottom result) in a broader region of the basin. The strengths of both the double jets and the broader regions of enhanced/retarded zonal flow are found to be determined by forcing in relatively small areas of the basin. The former are excited in the vicinity of saddle points of potential vorticity whereas the latter are excited primarily where the curvature of potential vorticity contours is large. The second model, a time dependent 2½ layer planetary geostrophic model is then used to investigate the spin-up problem. The model is forced by a uniform upwelling through each of the two interfaces. The density jump at the upper interface (e.g. the thermocline) is chosen to be ten times that at the lower interface, a disparity which leads to a separation in time scale between the fast and the slow waves of the system. Topography, however, induces a strong coupling between these two modes and results in a quick baroclinization of the flow over the topography. This baroclinization occurs well before the arrival of the nondispersive wave front from the eastern boundary and thus differs from the traditional view of spin-up

A theory of wind-driven circulation. I. Mid-ocean gyres

A theory of the wind-driven ocean circulation is presented in which the key feature is strong deformation of interior density layers and consequent production of closed geostrophic-contours by the flow itself. The constraint imposed on the subsurface flow by the imposition of a no flux condition where a geostrophic contour strikes a coastal boundary is thus removed. Within regions where the geostrophic contours close the potential vorticity is uniform...

Substitute solders

Somewhat in excess of one- fifth of the tin consumed in the United States goes into the manufacture of solders ; no one type of application, with the single exception of tin plate, uses more than one-third this amount. With the growing possibility of curtailment in tin supplies to the United States, it is appropriate that an effort be made to find satisfactory substitutes in an application such as this which is vital both to peace-time industry and to the manufacture of war materials

Shifting Surface Currents in the Northern North Atlantic Ocean

Analysis of surface drifter tracks in the North Atlantic Ocean from the time period 1990 to 2006 provides the first evidence that the Gulf Stream waters can have direct pathways to the Nordic Seas. Prior to 2000, the drifters entering the channels leading to the Nordic Seas originated in the western and central subpolar region. Since 2001 several paths from the western subtropics have been present in the drifter tracks leading to the Rockall Trough through which the most saline North Atlantic Waters pass to the Nordic Seas. Eddy kinetic energy from altimetry shows also the increased energy along the same paths as the drifters, These near surface changes have taken effect while the altimetry shows a continual weakening of the subpolar gyre. These findings highlight the changes in the vertical structure of the northern North Atlantic Ocean, its dynamics and exchanges with the higher latitudes, and show how pathways of the thermohaline circulation can open up and maintain or increase its intensity even as the basin-wide circulation spins down