Race, Class, And Gender In Boys\u27 Education: Repositioning Intersectionality Theory

Boys\u27 identities are distinctly gendered, racialized, and classed across disparate social and cultural contexts. Related intersectional identity processes are associated with boys\u27 academic success. While intersectionality has been utilized throughout boys\u27 education scholarship, a limited, light touch approach is often enacted. As a critical logic of interpretation, intersectionality theory accounts for race, class, and gender within equity-based empirical studies. The authors contend insufficient engagement with intersectionality may lead educational research on boys\u27 social and learner identities to become static. Examining boys\u27 identities through intersectional approaches reveals more complex insights particularly related to their school engagement. Critical of the recent boy crisis literature, this article strives to compel theorists of boys\u27 education to more fully leverage the history, constructs, and epistemologies of intersectionality

A unified model for the long and high jump

A simple model based on the maximum energy that an athlete can produce in a small time interval is used to describe the high and long jump. Conservation of angular momentum is used to explain why an athlete should run horizontally to perform a vertical jump. Our results agree with world records.Comment: Accepted for publication in Am. J. Phy

How dsDNA breathing enhances its flexibility and instability on short length scales

We study the unexpected high flexibility of short dsDNA which recently has been reported by a number of experiments. Via the Langevin dynamics simulation of our Breathing DNA model, first we observe the formation of bubbles within the duplex and also forks at the ends, with the size distributions independent of the contour length. We find that these local denaturations at a physiological temperature, despite their rare and transient presence, can lower the persistence length drastically for a short DNA segment in agreement with experiment

Minimizers with discontinuous velocities for the electromagnetic variational method

The electromagnetic two-body problem has \emph{neutral differential delay} equations of motion that, for generic boundary data, can have solutions with \emph{discontinuous} derivatives. If one wants to use these neutral differential delay equations with \emph{arbitrary} boundary data, solutions with discontinuous derivatives must be expected and allowed. Surprisingly, Wheeler-Feynman electrodynamics has a boundary value variational method for which minimizer trajectories with discontinuous derivatives are also expected, as we show here. The variational method defines continuous trajectories with piecewise defined velocities and accelerations, and electromagnetic fields defined \emph{by} the Euler-Lagrange equations \emph{% on} trajectory points. Here we use the piecewise defined minimizers with the Li{\'{e}}nard-Wierchert formulas to define generalized electromagnetic fields almost everywhere (but on sets of points of zero measure where the advanced/retarded velocities and/or accelerations are discontinuous). Along with this generalization we formulate the \emph{generalized absorber hypothesis} that the far fields vanish asymptotically \emph{almost everywhere%} and show that localized orbits with far fields vanishing almost everywhere \emph{must} have discontinuous velocities on sewing chains of breaking points. We give the general solution for localized orbits with vanishing far fields by solving a (linear) neutral differential delay equation for these far fields. We discuss the physics of orbits with discontinuous derivatives stressing the differences to the variational methods of classical mechanics and the existence of a spinorial four-current associated with the generalized variational electrodynamics.Comment: corrected minor typo: piecewise differentiable on closed instead of open interval

Translational Correlations in the Vortex Array at the Surface of a Type-II Superconductor

We discuss the statistical mechanics of magnetic flux lines in a finite-thickness slab of type-II superconductor. The long wavelength properties of a flux-line liquid in a slab geometry are described by a hydrodynamic free energy that incorporates the boundary conditions on the flux lines at the sample's surface as a surface contribution to the free energy. Bulk and surface weak disorder are modeled via Gaussian impurity potentials. This free energy is used to evaluate the two-dimensional structure factor of the flux-line tips at the sample surface. We find that surface interaction always dominates in determining the decay of translational correlations in the asymptotic long-wavelength limit. On the other hand, such large length scales have not been probed by the decoration experiments. Our results indicate that the translational correlations extracted from the analysis of the Bitter patterns are indeed representative of behavior of flux lines in the bulk.Comment: 23 pages, 1 figure (not included), harvmac.tex macro needed (e-mail requests to [email protected] SU-CM-92-01

Direct Determination of DNA Twist-Stretch Coupling

The symmetries of the DNA double helix require a new term in its linear response to stress: the coupling between twist and stretch. Recent experiments with torsionally-constrained single molecules give the first direct measurement of this important material parameter. We extract its value from a recent experiment of Strick et al. [Science 271 (1996) 1835] and find rough agreement with an independent experimental estimate recently given by Marko. We also present a very simple microscopic theory predicting a value comparable to the one observed.Comment: Plain TeX file; uses harvmac and epsf; .ps also available at http://dept.physics.upenn.edu/~nelson/twiststretch.ps or http://dept.physics.upenn.edu/~nelson/twiststretch.ps.g

Local government officials\u27 perspectives on regional councils of governments

The decades of the 1960s and 1970s were a time of rapid change in the operations of county and municipal governments. Citizen expectations regarding the scope and quality of local government services escalated rapidly. State and federal legislation and regulations resulted in higher standards for health care, housing, education, law enforcement, public assistance, personnel practices, and environmental conditions. Specialized services were mandated as a way of meeting the needs of the aged, of youth, of minorities, and of the disadvantaged.https://lib.dr.iastate.edu/specialreports/1084/thumbnail.jp

Neurospora crassa chromosome walks

Chromosome walks have been executed for all seven chromosomes of N. crassa, but the amount of coverage varies greatly, from less than 3% (LG V) to about 25% (LG VII). Overall, about 10% of the genome has been covered by chromosome walks (Table 1). All chromosome walks are shown with respect to the position on the chromosome, oriented from the left telomere to the right. The standard nomenclature for these genomic libraries is followed: pSV50 (Vollmer and Yanofsky 1986 Proc. Natl. Acad. Sci. USA 83:4869-4873), pMOcosX (Orbach 1994 Gene 150:159-162), EMBL3 (Yeadon and Catcheside 1995 Curr. Genet. 28:155-163), pCRD103 (Davis et al. 1994 Genetics 136:1297-1306), CBM1 (Cabibbo et al. 1991 Fungal Genet. Newsl. 38:68-70), CBM2 (Ballario et al. 1996 EMBO J. 15:1650-1657) and yeast artificial chromosome (YAC; Centola et al. 1994 Fungal Genet. Newsl. 41:23-33). For precise map positions of the cited alleles, refer to Perkins et al.(1982 Microbiol. Rev. 46:426-570) and Perkins (1992 Fungal Genet. Newsl. 39:61-70)

Study and development of acoustic treatment for jet engine tailpipes

A study and development program was accomplished to attenuate turbine noise generated in the JT3D turbofan engine. Analytical studies were used to design an acoustic liner for the tailpipe. Engine ground tests defined the tailpipe environmental factors and laboratory tests were used to support the analytical studies. Furnace-brazed, stainless steel, perforated sheet acoustic liners were designed, fabricated, installed, and ground tested in the tailpipe of a JT3D engine. Test results showed the turbine tones were suppressed below the level of the jet exhaust for most far field polar angles