Undoing Whiteness to Diversify Teacher Education and the Teaching Force

Various initiatives are underway in Minnesota and around the country to promote racial consciousness in K-12 teaching (R4615). Some of these show great promise for helping to realize goals related to racial equity and social justice articulated by key professional organizations guiding teacher education and educational research nationwide (AACTE; AERA; AESA). While enrollment statistics point to incremental gains being made toward diversifying the teaching force in Minnesota and nationwide, this pace lags behind the growth in diversity of the K-12 student population. At the same time, Minnesota’s teaching force remains over 90% white (MDE, 2020). Considering what research shows about curriculum and teaching practices reflecting the majority group’s interests (Sleeter, 2017), it is no coincidence that the state has produced some of the nation’s highest racial disparities in academic achievement (Shockman, 2019). This brief is offered as a call to complement recruiting efforts with a dismantling of existing white systems and practices that work to exclude or “filter” non-white teacher candidates out of teacher- preparatory programs and the teaching profession. As the American Association of Colleges for Teacher Education (AACTE) claimed in its 2022 call for conference proposals, “simply recruiting teachers from diverse backgrounds is insufficient. Efforts that sustain and affirm these teachers are necessary to the goal of diversifying the educator workforce.” In teacher preparation, this will entail undoing traditionally white practices known to alienate and drive teacher candidates of color away from teaching (Carter Andrews et al., 2019; Johnson & Lehner, 2020)

Knot Floer homology detects fibred knots

Ozsv\'ath and Szab\'o conjectured that knot Floer homology detects fibred knots in $S^3$. We will prove this conjecture for null-homologous knots in arbitrary closed 3--manifolds. Namely, if $K$ is a knot in a closed 3--manifold $Y$, $Y-K$ is irreducible, and $\hat{HFK}(Y,K)$ is monic, then $K$ is fibred. The proof relies on previous works due to Gabai, Ozsv\'ath--Szab\'o, Ghiggini and the author. A corollary is that if a knot in $S^3$ admits a lens space surgery, then the knot is fibred.Comment: version 4: incorporates referee's suggestions, to appear in Inventiones Mathematica

Bordered Floer homology and the spectral sequence of a branched double cover I

Given a link in the three-sphere, Z. Szab\'o and the second author constructed a spectral sequence starting at the Khovanov homology of the link and converging to the Heegaard Floer homology of its branched double-cover. The aim of this paper and its sequel is to explicitly calculate this spectral sequence, using bordered Floer homology. There are two primary ingredients in this computation: an explicit calculation of filtered bimodules associated to Dehn twists and a pairing theorem for polygons. In this paper we give the first ingredient, and so obtain a combinatorial spectral sequence from Khovanov homology to Heegaard Floer homology; in the sequel we show that this spectral sequence agrees with the previously known one.Comment: 45 pages, 16 figures. v2: Published versio

Functional redundancy of two C. elegans homologs of the histone chaperone Asf1 in germline DNA replication

AbstractEukaryotic genomes contain either one or two genes encoding homologs of the highly conserved histone chaperone Asf1, however, little is known of their in vivo roles in animal development. UNC-85 is one of the two Caenorhabditis elegans Asf1 homologs and functions in post-embryonic replication in neuroblasts. Although UNC-85 is broadly expressed in replicating cells, the specificity of the mutant phenotype suggested possible redundancy with the second C. elegans Asf1 homolog, ASFL-1. The asfl-1 mRNA is expressed in the meiotic region of the germline, and mutants in either Asf1 genes have reduced brood sizes and low penetrance defects in gametogenesis. The asfl-1, unc-85 double mutants are sterile, displaying defects in oogenesis and spermatogenesis, and analysis of DNA synthesis revealed that DNA replication in the germline is blocked. Analysis of somatic phenotypes previously observed in unc-85 mutants revealed that they are neither observed in asfl-1 mutants, nor enhanced in the double mutants, with the exception of enhanced male tail abnormalities in the double mutants. These results suggest that the two Asf1 homologs have partially overlapping functions in the germline, while UNC-85 is primarily responsible for several Asf1 functions in somatic cells, and is more generally involved in replication throughout development

Circular orbits and spin in black-hole initial data

The construction of initial data for black-hole binaries usually involves the choice of free parameters that define the spins of the black holes and essentially the eccentricity of the orbit. Such parameters must be chosen carefully to yield initial data with the desired physical properties. In this paper, we examine these choices in detail for the quasiequilibrium method coupled to apparent-horizon/quasiequilibrium boundary conditions. First, we compare two independent criteria for choosing the orbital frequency, the "Komar-mass condition" and the "effective-potential method," and find excellent agreement. Second, we implement quasi-local measures of the spin of the individual holes, calibrate these with corotating binaries, and revisit the construction of non-spinning black hole binaries. Higher-order effects, beyond those considered in earlier work, turn out to be important. Without those, supposedly non-spinning black holes have appreciable quasi-local spin; furthermore, the Komar-mass condition and effective potential method agree only when these higher-order effects are taken into account. We compute a new sequence of quasi-circular orbits for non-spinning black-hole binaries, and determine the innermost stable circular orbit of this sequence.Comment: 24 pages, 17 figures, accepted for publication in Physical Review D, revtex4; Fixed error in computing proper separation and updated figures and tables accordingly, added reference to Sec. IV.A, fixed minor error in Sec. IV.B, added new data to Tables IV and V, fixed 1 reference, fixed error in Eq. (A7b), included minor changes from PRD editin

Laser-Induced Spall Of Aluminum And Aluminum Alloys At High Strain Rates

We conducted laser-induced spall experiments aimed at studying how a material's microstructure affects the tensile fracture characteristics at high strain rates (> 10(6) s(-1)). We used the Z-Beamlet Laser at Sandia National Laboratory to drive shocks and to measure the spall strength of aluminum targets with various microstructures. The targets were recrystallized, high-purity aluminum (Al-HP RX), recrystallized aluminum + 3 wt.% magnesium (Al-3Mg RX), and cold-worked aluminum + 3 wt.% magnesium (Al-3Mg CW). The Al-3Mg RX and Al-3Mg CW are used to explore the roles that solid-solution alloying and cold-work strengthening play in the spall process. Using a line-VISAR (Velocity Interferometer System for Any Reflector) and analysis of recovered samples, we were able to measure spall strength and determine failure morphology in these targets. We find that the spall strength is highest for Al-HP RX. Analysis reveals that material grain size plays a vital role in the fracture morphology and spall strength results.Mechanical Engineerin

Experimental and Theoretical Studies of Axisymmetric Free Jets

Some experimental and theoretical studies have been made of axisymmetric free jets exhausting from sonic and supersonic nozzles into still air and into supersonic streams with a view toward problems associated with propulsive jets and the investigation of these problems. For jets exhausting into still air, consideration is given to the effects of jet Mach number, nozzle divergence angle, and jet static pressure ratio upon jet structure, jet wavelength, and the shape and curvature of the jet boundary. Studies of the effects of the ratio of specific heats of the jets are included are observations pertaining to jet noise and jet simulation. For jets exhausting into supersonic streams, an attempt has been made to present primarily theoretical certain jet interference effects and in formulating experimental studies. The primary variables considered are jet Mach number, free stream Mach number, jet static pressure ratio, ratio of specific heats of the jet, nozzle exit angle, and boattail angle. The simulation problem and the case of a hypothetical hypersonic vehicle are examined, A few experimental observations are included

‘Subjects and Objects: Material Expressions of Love and Loyalty in Seventeenth-Century England’, in special section on ‘Loyalties and Allegiances in Early Modern England’ in Journal of British Studies Vol. 48: 4 (October, 2009)

This article investigates how and where the emotive relations between subject and state were forged and how these ideas were manifested in early modern England. McShane describes an affective economy of loyalty, embodied in cheap and accessible political commodities: decorated objects made of clay, metals, and paper, on which precious household resources of time, money and emotion were spent. She argues that by engendering, inculcating and insinuating codes of political love into people’s ‘emotional, sensual, representational, and communicative’ lives, ‘loyal’ goods acted as vehicles and texts for what Victoria Kahn describes as ‘the supplementary role of the passions’ in ‘forging political obligation’ and the reformulation of ‘the duty to love’ of both subject and king in 17th-century England. McShane’s research contributes to a growing theme in scholarship, namely the active consumption of politically significant goods. This essay extends the range of objects under examination to include quotidian household items, shedding light on the dissemination and construction of early modern loyalty across a much wider social scale. The research draws on an extensive survey of collections held at the V&A, the Museum of London, Ashmolean Museum, Fitzwilliam Museum and Burrell Collection. Importantly, by putting illustrated print products back together with other political commodities in the early modern home, creating a broad archive of objects and text-objects where each informs the other, McShane’s approach challenges the typical social historical methodology, which uses material culture as merely illustrative of textual sources. This article was part of a special section on loyalty and allegiance in early modern England, co-edited by McShane with Dr Ted Vallance for one of the leading scholarly journals in the field. The material was drawn from a workshop on the topic held at the University of Liverpool funded by the British Academy, University of Liverpool and the Scouloudi Foundation (2007)

Secondary Natural Gas Recovery: Reservoir Heterogeneity and Potential for Reserve Growth through Infield Drilling: An Example from McAllen Ranch Field, Hidalgo County, Texas

Integrated engineering, geological, geophysical, and petrophysical analyses of McAllen Ranch field have delineated several controls on secondary recovery of natural gas. Barriers to the flow of natural gas within laterally continuous lower Vicksburg sandstone reservoirs can be demonstrated through finite-element modeling. These barriers are probably diagenetic in origin. In the B area of McAllen Ranch field, faults are unlikely to be the primary barriers to gas flow because faults were not inferred from analysis of high-quality three-dimensional seismic images between the key wells used in this study (Hill and others, 1991). Barriers result in incremental reserve additions when some reservoir domains contain no well completions. Areas containing potential incremental gas resources, identified through this analysis, were confirmed by subsequent recompletions in 1991. Three recompletions proposed by this project have proved successful. Our analysis of public domain production data indicates that new infield wells in the Vicksburg S reservoir have increased reserves 69 percent above an estimate made from analysis of 1980 public domain data. Additionally, more than 100 barrels per day of reserves has been added through new wells drilled between 1988 and 1991. Most of the McAllen Ranch Vicksburg S reserve increases are due to a geological reinterpretation that has stimulated infield step-out development of the Vicksburg S reservoir. Distributary-channel-fill sandstones are the most likely candidates to contain incremental reserves because they are laterally discontinuous and are predominant in areas where numerous reservoir sandstones are stacked.Bureau of Economic Geolog