Nonlinear modes of the tensor Dirac equation and CPT violation

Recently, it has been shown that Dirac's bispinor equation can be expressed, in an equivalent tensor form, as a constrained Yang-Mills equation in the limit of an infinitely large coupling constant. It was also shown that the free tensor Dirac equation is a completely integrable Hamiltonian system with Lie algebra type Poisson brackets, from which Fermi quantization can be derived directly without using bispinors. The Yang-Mills equation for a finite coupling constant is investigated. It is shown that the nonlinear Yang-Mills equation has exact plane wave solutions in one-to-one correspondence with the plane wave solutions of Dirac's bispinor equation. The theory of nonlinear dispersive waves is applied to establish the existence of wave packets. The CPT violation of these nonlinear wave packets, which could lead to new observable effects consistent with current experimental bounds, is investigated

Hestenes' Tetrad and Spin Connections

Defining a spin connection is necessary for formulating Dirac's bispinor equation in a curved space-time. Hestenes has shown that a bispinor field is equivalent to an orthonormal tetrad of vector fields together with a complex scalar field. In this paper, we show that using Hestenes' tetrad for the spin connection in a Riemannian space-time leads to a Yang-Mills formulation of the Dirac Lagrangian in which the bispinor field is mapped to a set of Yang-Mills gauge potentials and a complex scalar field. This result was previously proved for a Minkowski space-time using Fierz identities. As an application we derive several different non-Riemannian spin connections found in the literature directly from an arbitrary linear connection acting on Hestenes' tetrad and scalar fields. We also derive spin connections for which Dirac's bispinor equation is form invariant. Previous work has not considered form invariance of the Dirac equation as a criterion for defining a general spin connection

The Consequences of Authoritarian Populism in Britain

Authoritarian Populist was a label often hung on the Thatcher governments of the 1980s. Although the UK political landscape has changed enormously since 1990, the popular sentiments that underpinned Margaret Thatcher?s repeated electoral successes remain remarkably strong among British voters today. The paper uses extensive survey evidence to characterise what Authoritarian Populism means for voters in Britain today. The analysis shows that there is a coherent set of beliefs, held by a surprisingly large proportion of the UK electorate, which can reasonably be described as Authoritarian Pop ulist. These beliefs focus on the strong role that Britain should play in the world, cynicism about the operation of EU institutions, a virulent opposition to human rights, negative views towards immigration, and preferences for lower taxes and a smaller state. The analysis also shows that (controlling for a wide range of other relevant factors) these views have important consequences for patterns of party support, for likely voting in the forthcoming referendum on the EU, for (dis)satisfaction with Briti sh democracy, and for attitudes towards courts

Measuring a Kaluza-Klein radius smaller than the Planck length

Hestenes has shown that a bispinor field on a Minkowski space-time is equivalent to an orthonormal tetrad of one-forms together with a complex scalar field. More recently, the Dirac and Einstein equations were unified in a tetrad formulation of a Kaluza-Klein model which gives precisely the usual Dirac-Einstein Lagrangian. In this model, Dirac's bispinor equation is obtained in the limit for which the radius of higher compact dimensions of the Kaluza-Klein manifold becomes vanishingly small compared with the Planck length. For a small but finite radius, the Kaluza-Klein model predicts velocity splitting of single fermion wave packets. That is, the model predicts a single fermion wave packet will split into two wave packets with slightly different group velocities. Observation of such wave packet splits would determine the size of the Kaluza-Klein radius. If wave packet splits were not observed in experiments with currently achievable accuracies, the Kaluza-Klein radius would be at least twenty five orders of magnitude smaller than the Planck length

Prudence, Principle and Minimal Heuristics: British Public Opinion toward the Use of Military Force in Afghanistan and Libya

Research Highlights and Abstract This article shows: Clear pluralities of British survey respondents opposed their nation's military interventions in Afghanistan and Libya. Opposition to involvement in the conflicts mostly a function of the costs the missions would impose on the nation and concerns about the morality of the missions. Attitudes towards the parties and their leaders are weak predictors of the respondents' attitudes towards involving the nation's military in the conflict. Survey experiment reveals the positions leaders and parties took on sending additional British troops into Afghanistan did not prime support or opposition to such a ‘surge’. Scholarship is divided on the primary drivers of public support for the use of military force. This article addresses this controversy by comparing three competing models of British public opinion towards the use of military force in Afghanistan and Libya. Analyses of national survey data demonstrate that cost-benefit calculations and normative considerations have sizable effects, but leader images and other heuristics have very limited explanatory power. These results are buttressed by experimental evidence showing that leader cues have negligible impacts on attitudes towards participation in a military ‘surge’ in Afghanistan. The minimal role heuristics played in motivating citizen support and opposition to the conflicts in these two countries contrast with their significant relationship to citizen attitudes towards the British intervention in Iraq. These conflicting results suggest that the strength of leader and partisan cues may be animated by the intensity of inter-elite conflict over British involvement in military interventions. </jats:p

Taking Foreign Policy Personally: Personal Values and Foreign Policy Attitudes

Previous research has shown that on issues of foreign policy, individuals have “general stances,” “postures,” “dispositions” or “orientations” that inform their beliefs toward more discrete issues in international relations. While these approaches delineate the proximate sources of public opinion in the foreign policy domain, they evade an even more important question: what gives rise to these foreign policy orientations in the first place? Combining an original survey on a nationally representative sample of Americans with Schwartz’s theory of values from political psychology, we show that people take foreign policy personally: the same basic values we know people use to guide choices in their daily lives also travel to the domain of foreign affairs, offering one potential explanation why people who are otherwise uninformed about world politics nonetheless express coherent foreign policy beliefs

Equivalent forms of Dirac equations in curved spacetimes and generalized de Broglie relations

One may ask whether the relations between energy and frequency and between momentum and wave vector, introduced for matter waves by de Broglie, are rigorously valid in the presence of gravity. In this paper, we show this to be true for Dirac equations in a background of gravitational and electromagnetic fields. We first transform any Dirac equation into an equivalent canonical form, sometimes used in particular cases to solve Dirac equations in a curved spacetime. This canonical form is needed to apply the Whitham Lagrangian method. The latter method, unlike the WKB method, places no restriction on the magnitude of Planck's constant to obtain wave packets, and furthermore preserves the symmetries of the Dirac Lagrangian. We show using canonical Dirac fields in a curved spacetime, that the probability current has a Gordon decomposition into a convection current and a spin current, and that the spin current vanishes in the Whitham approximation, which explains the negligible effect of spin on wave packet solutions, independent of the size of Planck's constant. We further discuss the classical-quantum correspondence in a curved spacetime based on both Lagrangian and Hamiltonian formulations of the Whitham equations. We show that the generalized de Broglie relations in a curved spacetime are a direct consequence of Whitham's Lagrangian method, and not just a physical hypothesis as introduced by Einstein and de Broglie, and by many quantum mechanics textbooks.Comment: PDF, 32 pages in referee format. Added significant material on canonical forms of Dirac equations. Simplified Theorem 1 for normal Dirac equations. Added section on Gordon decomposition of the probability current. Encapsulated main results in the statement of Theorem

Foreign Policy and the Electoral Connection

Public opinion is central to representation, democratic accountability, and decision making. Yet, the public was long believed to be relatively uninterested in foreign affairs, absent an immediate threat to safety and welfare. It had become conventional to say that voting ends at water\u27s edge. We start the examination of the scholarly understanding of the role of foreign affairs in public opinion and voting at that low point of view. Much subsequent development saw an increasing degree of holding and using of attitudes and beliefs about foreign affairs among the public. Moving in parallel with developments in political psychology, theoretical and methodological advances led to an increasingly widely shared view that the public holds reasonably sensible and nuanced views, that these help shape their political behaviors, and that these, in turn, help shape and constrain foreign policy making

Characterization of Three-Dimensional Retinal Tissue Derived from Human Embryonic Stem Cells in Adherent Monolayer Cultures

Stem cell-based therapy of retinal degenerative conditions is a promising modality to treat blindness, but requires new strategies to improve the number of functionally integrating cells. Grafting semidifferentiated retinal tissue rather than progenitors allows preservation of tissue structure and connectivity in retinal grafts, mandatory for vision restoration. Using human embryonic stem cells (hESCs), we derived retinal tissue growing in adherent conditions consisting of conjoined neural retina and retinal pigment epithelial (RPE) cells and evaluated cell fate determination and maturation in this tissue. We found that deriving such tissue in adherent conditions robustly induces all eye field genes (RX, PAX6, LHX2, SIX3, SIX6) and produces four layers of pure populations of retinal cells: RPE (expressing NHERF1, EZRIN, RPE65, DCT, TYR, TYRP, MITF, PMEL), early photoreceptors (PRs) (coexpressing CRX and RCVRN), inner nuclear layer neurons (expressing CALB2), and retinal ganglion cells [RGCs, expressing BRN3B and Neurofilament (NF) 200]. Furthermore, we found that retinal progenitors divide at the apical side of the hESC-derived retinal tissue (next to the RPE layer) and then migrate toward the basal side, similar to that found during embryonic retinogenesis. We detected synaptogenesis in hESC-derived retinal tissue, and found neurons containing many synaptophysin-positive boutons within the RGC and PR layers. We also observed long NF200-positive axons projected by RGCs toward the apical side. Whole-cell recordings demonstrated that putative amacrine and/or ganglion cells exhibited electrophysiological responses reminiscent of those in normal retinal neurons. These responses included voltage-gated Na+ and K+ currents, depolarization-induced spiking, and responses to neurotransmitter receptor agonists. Differentiation in adherent conditions allows generation of long and flexible pieces of 3D retinal tissue suitable for isolating transplantable slices of tissue for retinal replacement therapies.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140208/1/scd.2015.0144.pd

“Fake news” may have limited effects beyond increasing beliefs in false claims

This is the final version. Available from the Shorenstein Center for Media, Politics, and Public Policy via the DOI in this recordData availability: The data and code necessary to replicate all the findings in this article will be made available on Dataverse upon publication of this article. Per our human subjects protocols, we will protect respondent privacy by only including individual-level summary data of respondents’ web consumption (e.g., number of untrustworthy websites visited) in the replication data.Since 2016, there has been an explosion of interest in misinformation and its role in elections. Research by news outlets, government agencies, and academics alike has shown that millions of Americans have been exposed to dubious political news online. However, relatively little research has focused on documenting the effects of consuming this content. Our results suggest that many claims about the effects of exposure to false news may be overstated, or, at the very least, misunderstood.Democracy FundEuropean Union Horizon 2020Nelson A. Rockefeller Center, Dartmouth CollegeWeidenbaum Center on the Economy, Government, and Public Policy, Washington University, St. Louis