Degeneracy between mass and spin in black-hole-binary waveforms

We explore the degeneracy between mass and spin in gravitational waveforms emitted by black-hole binary coalescences. We focus on spin-aligned waveforms and obtain our results using phenomenological models that were tuned to numerical-relativity simulations. A degeneracy is known for low-mass binaries (particularly neutron-star binaries), where gravitational-wave detectors are sensitive to only the inspiral phase, and the waveform can be modelled by post-Newtonian theory. Here, we consider black-hole binaries, where detectors will also be sensitive to the merger and ringdown, and demonstrate that the degeneracy persists across a broad mass range. At low masses, the degeneracy is between mass ratio and total spin, with chirp mass accurately determined. At higher masses, the degeneracy persists but is not so clearly characterised by constant chirp mass as the merger and ringdown become more significant. We consider the importance of this degeneracy both for performing searches (including searches where only non-spinning templates are used) and in parameter extraction from observed systems. We compare observational capabilities between the early (~2015) and final (2018 onwards) versions of the Advanced LIGO detector.Comment: 11 pages, 9 figure

Essay – Finding the Error in Daubert

The Supreme Court in Daubert v. Merrell Dow Pharmaceuticals, Inc. laid down the standard for admissibility of expert testimony. We believe the best standard is simpler than the one chosen by the Court: The Daubert standard really is about discerning the trustworthiness of expert, and trustworthiness is best determined through an expert’s accounting of the error within his testimony. Lower courts have struggled with the Daubert standard. We offer evidence of the problem and propose a new standard that would capture the essence of Daubert but significantly simplify its application

What Can Students Do With the Words They Know? An ELA Teacher Takes on Science

The Common Core State Standard and Next Generation Science Standards emphasize language and literacy across disciplines, requiring shifts in teaching practices and inventive approaches. This case study focuses on the instructional decision-making and activities of one uniquely experienced and qualified seventh-grade science teacher, whose English Language Arts background made her approach to vocabulary instruction distinctive, as she selected focus vocabulary and incorporated morphological instruction and lexical enhancement into science teaching practices. Results highlight the differences between content literacy and disciplinary literacy and the pitfalls of applying broad literacy strategies without deep consideration of disciplinary knowledge and requirements and provide examples of naturalistic ways to incorporate morphology instruction into science instructional conversations to enhance students’ relational knowledge

Sentence repetition in adolescents with specific language impairments and autism: an investigation of complex syntax

Background: Recent studies have indicated that many children with autism spectrum disorders present with language difficulties that are similar to those of children with specific language impairments, leading some to argue for similar structural deficits in these two disorders. Aims: Repetition of sentences involving long-distance dependencies was used to investigate complex syntax in these groups. Methods & Procedures: Adolescents with specific language impairments (mean age = 15;3, n = 14) and autism spectrum disorders plus language impairment (autism plus language impairment; mean age = 14;8, n = 16) were recruited alongside typically developing adolescents (mean age = 14;4, n = 17). They were required to repeat sentences containing relative clauses that varied in syntactic complexity. Outcomes & Results: The adolescents with specific language impairments presented with greater syntactic difficulties than the adolescents with autism plus language impairment, as manifested by higher error rates on the more complex object relative clauses, and a greater tendency to make syntactic changes during repetition. Conclusions & Implications: Adolescents with specific language impairments may have more severe syntactic difficulties than adolescents with autism plus language impairment, possibly due to their short-term memory limitations

Not a stale metaphor: The continued relevance of pedagogical content knowledge for science research and education

Pedagogical content knowledge (PCK) is a foundation for teacher standards such as the Interstate Teacher Assessment and Support Consortium (InTASC) (Council of Chief State School Officers, 2011) and a critical element of teacher preparation and professional development for multiple fields, including science teaching (Purzer, Moore, Baker, & Berland, 2014). But several years ago Settlage (2013) presented a powerful critique of PCK, rejecting the way it positions knowledge in the abstract, “solely ... what teachers store in their heads” (p. 10) and calling for more evidence connecting PCK conceptualisations to actual teaching activity. In truth, theoretical descriptions of PCK abound (Darling -Hammond & Bransford, 2005; Hashweh, 2005; Lee & Luft, 2008) and most utilise the lens of the researcher (Lee & Luft, 2008). While this helps us conceptualise teaching and imagine what could be, what is needed are more illustrations of what is

Gaining Access to the Language of Science: A Research Partnership for Disciplined, Discursive Ways to Select and Assess Vocabulary Knowledge

To equalize access to science learning across genders and demographic groups, access to the disciplinary language of science is one place to start. The language of science is highly challenging and specialized, and difficulties acquiring this language contribute to disparities in science achievement across diverse student groups. This study used a pre-post design to analyze effectiveness of a brief classroom science vocabulary assessment designed to assess receptive and productive vocabulary knowledge across multiple sections of one 7th grade science teacher’s class. Vocabulary was selected and analysis conducted by an interdisciplinary research partnership including the science teacher, a literacy specialist, and a scientist. The resulting model presents an assessment that evaluates receptive knowledge and productive use of science language and reinforces vocabulary theory: learning words is incremental and multidimensional, and assessment should address this specialized skill in principled, disciplined ways