5,998 research outputs found
All Pain, Whose Gain? A Fifty-State Analysis of the Independent State Legislature Doctrine for Redistricting
The “Independent State Legislature” (ISL) doctrine has recently been offered as a reinterpretation of legislative control over federal elections and may upend decades of election law precedent. Based on Article I of the U.S. Constitution, the ISL doctrine holds that such authority of state legislatures potentially overrides state constitutions, as well as state courts, citizen initiatives, and even the governor. The original political goals of the ISL doctrine were the 2000 and 2016 Presidential elections. The doctrine has recently come before the Supreme Court in Moore v. Harper, a case concerning redistricting, and could open the door to increased gerrymandering of U.S. congressional districts. Here we analyze the practical consequences in all fifty states. We find that such a change in redistricting law would be highly asymmetric to the major political parties, giving considerable advantage to Democrats because it would undo an existing propensity for reform or judicial intervention in Democratic-leaning and swing states. This asymmetry raises questions of the desirability of introducing the ISL to questions of redistricting
A systems framework for remedying dysfunction in U.S. democracy
Democracy often fails to meet its ideals, and these failures may be made
worse by electoral institutions. Unwanted outcomes include polarized
institutions, unresponsive representatives, and the ability of a faction of
voters to gain power at the expense of the majority. Various reforms have been
proposed to address these problems, but their effectiveness is difficult to
predict against a backdrop of complex interactions. Here we outline a path for
systems-level modeling to help understand and optimize repairs to U.S.
democracy. Following the tradition of engineering and biology, models of
systems include mechanisms with dynamical properties that include
nonlinearities and amplification (voting rules), positive feedback mechanisms
(single-party control, gerrymandering), negative feedback (checks and
balances), integration over time (lifetime judicial appointments), and low
dimensionality (polarization). To illustrate a systems-level approach we
analyze three emergent phenomena: low dimensionality, elite polarization, and
anti-majoritarianism in legislatures. In each case, long-standing rules now
contribute to undesirable outcomes as a consequence of changes in the political
environment. Theoretical understanding at a general level will also help
evaluate whether a proposed reform's benefits will materialize and be lasting,
especially as conditions change again. In this way, rigorous modeling may not
only shape new lines of research, but aid in the design of effective and
lasting reform
Spike Timing Dependent Plasticity: A Consequence of More Fundamental Learning Rules
Spike timing dependent plasticity (STDP) is a phenomenon in which the precise timing of spikes affects the sign and magnitude of changes in synaptic strength. STDP is often interpreted as the comprehensive learning rule for a synapse – the “first law” of synaptic plasticity. This interpretation is made explicit in theoretical models in which the total plasticity produced by complex spike patterns results from a superposition of the effects of all spike pairs. Although such models are appealing for their simplicity, they can fail dramatically. For example, the measured single-spike learning rule between hippocampal CA3 and CA1 pyramidal neurons does not predict the existence of long-term potentiation one of the best-known forms of synaptic plasticity. Layers of complexity have been added to the basic STDP model to repair predictive failures, but they have been outstripped by experimental data. We propose an alternate first law: neural activity triggers changes in key biochemical intermediates, which act as a more direct trigger of plasticity mechanisms. One particularly successful model uses intracellular calcium as the intermediate and can account for many observed properties of bidirectional plasticity. In this formulation, STDP is not itself the basis for explaining other forms of plasticity, but is instead a consequence of changes in the biochemical intermediate, calcium. Eventually a mechanism-based framework for learning rules should include other messengers, discrete change at individual synapses, spread of plasticity among neighboring synapses, and priming of hidden processes that change a synapse's susceptibility to future change. Mechanism-based models provide a rich framework for the computational representation of synaptic plasticity
Leading-Order Actions of Goldstino Fields
This paper starts with a self-contained discussion of the so-called
Akulov-Volkov action S_AV, which is traditionally taken to be the leading-order
action of Goldstino field. Explicit expressions for S_AV and its chiral version
S_AV^ch are presented. We then turn to the issue on how these actions are
related to the leading-order action S_NL proposed in the newly proposed
constrained superfield formalism. We show that S_NL may yield S_AV/S_AV^ch or a
totally different action S_KS, depending on how the auxiliary field in the
former is integrated out. However, S_KS and S_AV/S_AV^ch always yield the same
S-matrix elements, as one would have expected from general considerations in
quantum field theory.Comment: Minor changes, version to appear in European Physical Journal
Nonlinear Realization of Spontaneously Broken N=1 Supersymmetry Revisited
This paper revisits the nonlinear realization of spontaneously broken N=1
supersymmetry. It is shown that the constrained superfield formalism can be
reinterpreted in the language of standard realization of nonlinear
supersymmetry via a new and simpler route. Explicit formulas of actions are
presented for general renormalizable theories with or without gauge
interactions. The nonlinear Wess-Zumino gauge is discussed and relations are
pointed out for different definitions of gauge fields. In addition, a general
procedure is provided to deal with theories of arbitrary Kahler potentials.Comment: 1+18 pages, LaTe
Superalgebra and Conservative Quantities in N=1 Self-dual Supergravity
The N=1 self-dual supergravity has SL(2,C) and the left-handed and right
-handed local supersymmetries. These symmetries result in SU(2) charges as the
angular-momentum and the supercharges. The model possesses also the invariance
under the general translation transforms and this invariance leads to the
energy-momentum. All the definitions are generally covariant . As the SU(2)
charges and the energy-momentum we obtained previously constituting the
3-Poincare algebra in the Ashtekar's complex gravity, the SU(2) charges, the
supercharges and the energy-momentum here also restore the super-Poincare
algebra, and this serves to support the reasonableness of their
interpretations.Comment: 18 pages, Latex, no figure
Fluorescence-Based Monitoring of In Vivo Neural Activity Using a Circuit-Tracing Pseudorabies Virus
The study of coordinated activity in neuronal circuits has been challenging without a method to simultaneously report activity and connectivity. Here we present the first use of pseudorabies virus (PRV), which spreads through synaptically connected neurons, to express a fluorescent calcium indicator protein and monitor neuronal activity in a living animal. Fluorescence signals were proportional to action potential number and could reliably detect single action potentials in vitro. With two-photon imaging in vivo, we observed both spontaneous and stimulated activity in neurons of infected murine peripheral autonomic submandibular ganglia (SMG). We optically recorded the SMG response in the salivary circuit to direct electrical stimulation of the presynaptic axons and to physiologically relevant sensory stimulation of the oral cavity. During a time window of 48 hours after inoculation, few spontaneous transients occurred. By 72 hours, we identified more frequent and prolonged spontaneous calcium transients, suggestive of neuronal or tissue responses to infection that influence calcium signaling. Our work establishes in vivo investigation of physiological neuronal circuit activity and subsequent effects of infection with single cell resolution
Contributions to the optical linewidth of shallow donor - bound excitonic transition in ZnO
We study the donor-bound exciton optical linewidth properties of Al, Ga and
In donor ensembles in single-crystal zinc oxide (ZnO). Neutral shallow donors
(D) in ZnO are spin qubits with optical access via the donor-bound exciton
(DX). This spin-photon interface enables applications in quantum
networking, memories and transduction. Essential optical parameters which
impact the spin-photon interface include radiative lifetime, optical
inhomogeneous and homogeneous linewidth and optical depth. The ensemble
photoluminescence linewidth ranges from 4-11 GHz, less than two orders of
magnitude larger than the expected lifetime-limited linewidth. The ensemble
linewidth remains narrow in absorption measurements through the 300
m-thick sample, which has an estimated optical depth up to several
hundred. Homogeneous broadening of the ensemble line due to phonons is
consistent with thermal population relaxation between DX states. This
thermal relaxation mechanism has negligible contribution to the total linewidth
at 2 K. We find that inhomogeneous broadening due to the disordered isotopic
environment in natural ZnO is significant, ranging from 1.9 GHz - 2.2 GHz.
Two-laser spectral anti-hole burning measurements, which can be used to measure
the homogeneous linewidth in an ensemble, however, reveal spectral anti-hole
linewidths similar to the single laser ensemble linewidth. Despite this
broadening, the high homogeneity, large optical depth and potential for isotope
purification indicate that the optical properties of the ZnO donor-bound
exciton are promising for a wide range of quantum technologies and motivate a
need to improve the isotope and chemical purity of ZnO for quantum
technologies.Comment: 22 pages, 12 figure
- …