Full-day kindergarten versus half-day kindergarten: which has more advantages for children with disabilities?

The purpose of this study was to compare academic and social skills of children with disabilities enrolled in both half-day and full-day kindergarten programs. Four boys, between the ages of 5 and 6, participated in the study. Of those, two were enrolled in a half-day program, and the other two were in a full-day program. Over a 4.5 month period, the children\u27s academic skills were measured by the Kindergarten Readiness Test, and their behaviors were observed. A single subject research design with AB phases was used. Their scores were collected in three weeks as baseline data and their progress was recorded in six weeks as intervention data. All children made progress in identifying alphabetic letters, numerical numbers, geometric shapes, sight words, individual name, address, phone number and birthday, but the trend of progress was slightly accelerated by the full-day students. Meanwhile, a teacher/parent survey pertaining to their perceptions on both programs was provided respectively. All four participating teachers preferred teaching in the full-day kindergarten because they had more time to teach and reinforce their lessons throughout the day. All four participating parents reported that children had an academic advantage by being enrolled in a full-day kindergarten program, however two parents also indicated that a full-day was too long for young children. The results showed that full-day students have a slight advantage academically over the half-day students, however, there was no difference between the two groups in learning social skills

Particle acceleration in a reconnecting current sheet: PIC simulation

The acceleration of protons and electrons in a reconnecting current sheet (RCS) is simulated with a particle-in-cell (PIC) 2D3V code for the proton-to-electron mass ratio of 100. The electro-magnetic configuration forming the RCS incorporates all three components of the magnetic field (including the guiding field) and a drifted electric field. PIC simulations reveal that there is a polarisation electric field that appears during acceleration owing to a separation of electrons from protons towards the midplane of the RCS. If the plasma density is low, the polarisation field is weak and the particle trajectories in the PIC simulations are similar to those in the test particle (TP) approach. For the higher plasma density the polarisation field is stronger and it affects the trajectories of protons by increasing their orbits during acceleration. This field also leads to a less asymmetrical abundances of ejected protons towards the midplane in comparison with the TP approach. For a given magnetic topology electrons in PIC simulations are ejected to the same semispace as protons, contrary to the TP results. This happens because the polarisation field extends far beyond the thickness of a current sheet. This field decelerates the electrons, which are initially ejected into the semispace opposite to the protons, returns them back to the RCS, and, eventually, leads to the electron ejection into the same semispace as protons. Energy distribution of the ejected electrons is rather wide and single-peak, contrary to the two-peak narrow-energy distribution obtained in the TP approach. In the case of a strong guiding field, the mean energy of the ejected electrons is found to be smaller than it is predicted analytically and by the TP simulations.Comment: 12 pages, 11 figures, J. Plasma Physics (accepted

Indeterminacy and instability in Petschek reconnection

We explain two puzzling aspects of Petschek's model for fast reconnection. One is its failure to occur in plasma simulations with uniform resistivity. The other is its inability to provide anything more than an upper limit for the reconnection rate. We have found that previously published analytical solutions based on Petschek's model are structurally unstable if the electrical resistivity is uniform. The structural instability is associated with the presence of an essential singularity at the X-line that is unphysical. By requiring that such a singularity does not exist, we obtain a formula that predicts a specific rate of reconnection. For uniform resistivity, reconnection can only occur at the slow, Sweet-Parker rate. For nonuniform resistivity, reconnection can occur at a much faster rate provided that the resistivity profile is not too flat near the X-line. If this condition is satisfied, then the scale length of the nonuniformity determines the reconnection rate

Flux and field line conservation in 3--D nonideal MHD flows: Remarks about criteria for 3--D reconnection without magnetic neutral points

We make some remarks on reconnection in plasmas and want to present some calculations related to the problem of finding velocity fields which conserve magnetic flux or at least magnetic field lines. Hereby we start from views and definitions of ideal and non-ideal flows on one hand, and of reconnective and non-reconnective plasma dynamics on the other hand. Our considerations give additional insights into the discussion on violations of the frozen--in field concept which started recently with the papers by Baranov & Fahr (2003a; 2003b). We find a correlation between the nonidealness which is given by a generalized form of the Ohm's law and a general transporting velocity, which is field line conserving.Comment: 9 pages, 2 figures, submitted to Solar Physic

Upset Simulation and Training Initiatives for U.S. Navy Commercial Derived Aircraft

Militarized versions of commercial platforms are growing in popularity due to many logistical benefits in the form of commercial off-the-shelf (COTS) parts, established production methods, and commonality for different certifications. Commercial data and best practices are often leveraged to reduce procurement and engineering development costs. While the developmental and cost reduction benefits are clear, these militarized aircraft are routinely operated in flight at significantly different conditions and in significantly different manners than for routine commercial flight. Therefore they are at a higher risk of flight envelope exceedance. This risk may lead to departure from controlled flight and/or aircraft loss1. Historically, the risk of departure from controlled flight for military aircraft has been mitigated by piloted simulation training and engineering analysis of typical aircraft response. High-agility military aircraft simulation databases are typically developed to include high angles of attack (AoA) and sideslip due to the dynamic nature of their missions and have been developed for many tactical configurations over the previous decades. These aircraft simulations allow for a more thorough understanding of the vehicle flight dynamics characteristics at high AoA and sideslip. In recent years, government sponsored research on transport airplane aerodynamic characteristics at high angles of attack has produced a growing understanding of stall/post-stall behavior. This research along with recent commercial airline training initiatives has resulted in improved understanding of simulator-based training requirements and simulator model fidelity.2-5 In addition, inflight training research over the past decade has produced a database of pilot performance and recurrency metrics6. Innovative solutions to aerodynamically model large commercial aircraft for upset conditions such as high AoA, high sideslip, and ballistic damage, as well as capability to accurately account for scaling factors, is necessary to develop realistic engineering and training simulations. Such simulations should significantly reduce the risk of departure from controlled flight, loss of aircraft, and ease the airworthiness certification process. The characteristics of commercial derivative aircraft are exemplified by the P-8A Multi-mission Maritime Aircraft (MMA) aircraft, and the largest benefits of initial investigation are likely to be yielded from this platform. The database produced would also be utilized by flight dynamics engineers as a means to further develop and investigate vehicle flight characteristics as mission tactics evolve through the years ahead. This paper will describe ongoing efforts by the U.S. Navy to develop a methodology for simulation and training for large commercial-derived transport aircraft at unusual attitudes, typically experienced during an aircraft upset. This methodology will be applied to a representative Navy aircraft (P-8A) and utilized to develop a robust simulation that should accurately represent aircraft response in these extremes. Simulation capabilities would then extend to flight dynamics analysis and simulation, as well as potential training applications. Recent evaluations of integrated academic, ground-based simulation, and in-flight upset training will be described along with important lessons learned, specific to military requirements

Wafer scale texturing of LiNbO3

We report a novel technique for micro texturing of LiNbO<sub>3</sub>. Well-defined raised ridges and etched trenches are demonstrated. This technique is suitable for the realization of surface relief gratings and photonic crystals

Locating current sheets in the solar corona

Current sheets are essential for energy dissipation in the solar corona, in particular by enabling magnetic reconnection. Unfortunately, sufficiently thin current sheets cannot be resolved observationally and the theory of their formation is an unresolved issue as well. We consider two predictors of coronal current concentrations, both based on geometrical or even topological properties of a force free coronal magnetic field. First, there are separatrices related to magnetic nulls. Through separatrices the magnetic connectivity changes discontinuously. Coronal magnetic nulls are, however, very rare. At second, inspired by the concept of generalized magnetic reconnection without nulls, quasi-separatrix layers (QSL) were suggested. Through QSL the magnetic connectivity changes continuously, though strongly. The strength of the connectivity change can be quantified by measuring the squashing of the flux tubes which connect the magnetically conjugated photospheres. We verify the QSL and separatrix concepts by comparing the sites of magnetic nulls and enhanced squashing with the location of current concentrations in the corona. Due to the known difficulties of their direct observation we simulated the coronal current sheets by numerically calculating the response of the corona to energy input from the photosphere heating a simultaneously observed EUV Bright Point. We did not find coronal current sheets not at the separatrices but at several QSL locations. The reason is that although the geometrical properties of force free extrapolated magnetic fields can indeed, hint at possible current concentrations, a necessary condition for current sheet formation is the local energy input into the corona

Quaternionic factorization of the Schroedinger operator and its applications to some first order systems of mathematical physics

We consider the following first order systems of mathematical physics. 1.The Dirac equation with scalar potential. 2.The Dirac equation with electric potential. 3.The Dirac equation with pseudoscalar potential. 4.The system describing non-linear force free magnetic fields or Beltrami fields with nonconstant proportionality factor. 5.The Maxwell equations for slowly changing media. 6.The static Maxwell system. We show that all this variety of first order systems reduces to a single quaternionic equation the analysis of which in its turn reduces to the solution of a Schroedinger equation with biquaternionic potential. In some important situations the biquaternionic potential can be diagonalized and converted into scalar potentials

On the Centenary of the Greatest «Robbery» in the History of the Russian Church: the Renovationist False Council of 1923 Through the Eyes of Atheists, Schismatics and Orthodox Contemporaries

The article examines the contemporaries’ perception of the Renovationist “Local Council” of 1923, the central event of the largest church schism in the history of Russia. It shows the view of its main unofficial initiators and curators: Chairman of the Revolutionary Military Council L. D. Trotsky (Bronstein) and other Party and Chekist figures and institutions, which makes it possible to understand why this pseudo-council was needed and how it was guided to the intended goal. A brief overview of publications dedicated to this «Council» in the Communist press (“Pravda”, “Izvestia VTsIK”, “Bezboshnik”) is given. Next, the renovationist press is considered, both time-based and targeted (three editions of the false council materials, carried out in the 1920s). The publications of the schismatics fully convey the pathos of the church revolutionaries, on the one hand, and on the other — expose their spiritual and moral inconsistency (that is particularly evident in case of bishop Antonin (Granovsky), nominal chairman of the “Local Council”). The last part of the article shows the reaction to the false council of the Orthodox zealots of that time — from the hierarchs led by Holy Patriarch Tikhon, to the outraged church commoners who expressed their attitude to the “Judases” (Antonin, etc.), using the materials at hand. The most obvious historical analogy that the Orthodox saw when assessing the Moscow schismatic assembly of 1923 was the “Robber Council” in Ephesus, held in 449. In general, almost all concerned contemporaries of the event saw it primarily as a political action. The apparent lack of ecclesiality of the Renovationist «Local Council» strongly exposed the schismatics themselves and largely predetermined their ecclesiological collapse

Self-similar solution of fast magnetic reconnection: Semi-analytic study of inflow region

An evolutionary process of the fast magnetic reconnection in ``free space'' which is free from any influence of outer circumstance has been studied semi-analytically, and a self-similarly expanding solution has been obtained. The semi-analytic solution is consistent with the results of our numerical simulations performed in our previous paper (see Nitta et al. 2001). This semi-analytic study confirms the existence of self-similar growth. On the other hand, the numerical study by time dependent computer simulation clarifies the stability of the self-similar growth with respect to any MHD mode. These results confirm the stable self-similar evolution of the fast magnetic reconnection system.Comment: 15 pages, 7 figure