Cognitive bias, scepticism and understanding

In recent work, Mark Alfano (2012; 2014) and Jennifer Saul (2013) have put forward a similar kind of provocative sceptical challenge. Both appeal to recent literature in empirical psychology to show that our judgments across a wide range of cases are riddled with unreliable cognitive heuristics and biases. Likewise, they both conclude that we know a lot less than we have hitherto supposed, at least on standard conceptions of what knowledge involves. It is argued that even if one grants the empirical claims that Saul and Alfano make, the sceptical conclusion that they canvass might not be as dramatic as it first appears. It is further argued, however, that one can reinstate a more dramatic sceptical conclusion by targeting their argument not at knowledge but rather at the distinct (and distinctively valuable) epistemic standing of understanding

Bayesian Model Selection with Future 21cm Observations of The Epoch of Reionisation

We apply Bayesian statistics to perform model selection on different reionisation scenarios via the Multinest algorithm. Initially, we recover the results shown by 21CMMC for the parameter estimation of 21cmFAST models. We proceed to test several toy models of the Epoch of Reionisation (EoR) defined in contrasting morphology and scale. We find that LOFAR observations are unlikely to allow model selection even with long integration times. HERA would require 61 dipoles to perform the same analysis in 1080 hours, and becomes comparable to the SKA with 217 dipoles. We find the SKA requires only 324 hours of observation to conclusively distinguish between our models. Once model selection is achievable, an analysis of observational priors is performed finding that neutral fraction checks at specific redshifts add little to no inference. We show the difficulties in model selection at the level of distinguishing fiducial parameters within a model or distinguishing galaxies with a constant versus power law mass-to-light ratio. Finally, we explore the use of the Savage-Dickey density ratio to show the redundancy of the parameter Rmfp within 21cmFAST.Comment: 20 pages, 16 figures - Accepted for publication by MNRA

The potential role of ePortfolios in the Teaching Excellence Framework

Current debates on HE policy in the UK are dominated by the evolving Teaching Excellence Framework (TEF) which will soon involve the government establishing key metrics.  In this context, and seizing this valuable moment in policy formation, we here provide a brief foray into the multiple aspects of ‘teaching excellence’ (TE) as a basis to highlight both the complexity of identifying ways to measure it and the shortcomings of existing official developments.  In the absence of a clear conceptual understanding of the learning processes and the role of teaching which apparently underpins the TEF, we present a model of the learning process to which the indicators currently proposed by the authorities can be related.  We propose that ePortfolios can play a special role in the TEF in capturing the qualitative outcomes of learning processes which, importantly, reflect the student perspective in terms of goals, learning experiences and achievement.  These are both crucial yet missing elements of the proposals to date. Finally, we provide some examples of how information from ePortfolios could be used by HE institutions to enhance their institutional submissions to the TEF.

Measurement of Holmium Rydberg series through MOT depletion spectroscopy

We report measurements of the absolute excitation frequencies of $^{165}$Ho $4f^{11}6sns$ and $4f^{11}6snd$ odd-parity Rydberg series. The states are detected through depletion of a magneto-optical trap via a two-photon excitation scheme. Measurements of 162 Rydberg levels in the range $n=40-101$ yield quantum defects well described by the Rydberg-Ritz formula. We observe a strong perturbation in the $ns$ series around $n=51$ due to an unidentified interloper at 48515.47(4) cm$^{-1}$. From the series convergence, we determine the first ionization potential $E_\mathrm{IP}=48565.939(4)$ cm$^{-1}$, which is three orders of magnitude more accurate than previous work. This work represents the first time such spectroscopy has been done in Holmium and is an important step towards using Ho atoms for collective encoding of a quantum register.Comment: 6 figure

Single Atom Imaging with an sCMOS camera

Single atom imaging requires discrimination of weak photon count events above background and has typically been performed using either EMCCD cameras, photomultiplier tubes or single photon counting modules. sCMOS provides a cost effective and highly scalable alternative to other single atom imaging technologies, offering fast readout and larger sensor dimensions. We demonstrate single atom resolved imaging of two site-addressable single atom traps separated by 10~$\mu$m using an sCMOS camera, offering a competitive signal-to-noise ratio at intermediate count rates to allow high fidelity readout discrimination (error $<10^{-6}$) and sub-$\mu$m spatial resolution for applications in quantum technologies.Comment: 4 pages, 4 figure

Rewriting the Constitution: An Economic Analysis of the Constitutional Amendment Process

In this Article, the authors develop an economic theory of the constitutional amendment process under Article V, focusing particularly on the roles that Congress and interest groups play in that process. The authors construct a model to predict when an interest group will seek an amendment rather than a statute to further its interests, highlighting how interest group maintenance costs and anticipated opposition affect that choice. They then discuss the efficiency goals of constitutionalism—precommitment and reduction of agency costs—and argue that the structure of the amendment process under Article V prevents realization of these goals. The authors contrast the Bill of Rights amendments, which established precommitments and reduced the agency costs of government, with the latter seventeen amendments, which expanded the federal government and increased agency costs. They attribute the change in the nature of the amendments to the interest-group domination of the political process and Congress\u27 control over the constitutional amendment agenda. The authors conclude that the Founders\u27 intent to put the Constitution beyond the reach of factions backfired: although factions cannot control the content of the Constitution, neither can the majority. In fact, Article V prevents the majority from precommiting itself and hinders its ability to control the agency costs of government, as evidenced by the history of the failed amendments. Although the authors conclude that Article V thwarts the efficiency goals of constitutionalism, they predict that little can be done to remedy this flaw

Assembly vs. direct launch of transfer vehicles

A top level assessment is performed of the relative impacts of on-orbit assembly of the lunar or Mars transfer vehicles versus direct launch. The objective is to identify the major option paths for the Earth-to-orbit, ETO, transportation systems. Heavy lift launch vehicles, if large enough, could reduce or eliminate on-orbit assembly. However, with every new approach, there are always counter-balancing considerations and it is the objective to begin the delineation of the necessary follow-on trade study issues