cssi/SciSciGPT-SciSciNet huggingface dataset:
Low-lying zeros of L-functions with orthogonal symmetry

We investigate the moments of a smooth counting function of the zeros near the central point of L-functions of weight k cuspidal newforms of prime level N. We split by the sign of the functional equations and show that for test functions whose Fourier transform is supported in (−1/n,1/n), as N→∞ the first n centered moments are Gaussian. By extending the support to (−1/(n−1),1/(n−1)), we see non-Gaussian behavior; in particular, the odd-centered moments are nonzero for such test functions. If we do not split by sign, we obtain Gaussian behavior for support in (−2/n,2/n) if 2k≥n. The nth-centered moments agree with random matrix theory in this extended range, providing additional support for the Katz-Sarnak conjectures. The proof requires calculating multidimensional integrals of the nondiagonal terms in the Bessel-Kloosterman expansion of the Petersson formula. We convert these multidimensional integrals to one-dimensional integrals already considered in the work of Iwaniec, Luo, and Sarnak [ILS] and derive a new and more tractable expression for the nth-centered moments for such test functions. This new formula facilitates comparisons between number theory and random matrix theory for test functions supported in (−1/(n−1),1/(n−1)) by simplifying the combinatorial arguments. As an application we obtain bounds for the percentage of such cusp forms with a given order of vanishing at the central point
Weak Chaos from Tsallis Entropy

We present a geometric, model-independent, argument that aims to explain why the Tsallis entropy describes systems exhibiting “weak chaos”, namely systems whose underlying dynamics has vanishing largest Lyapunov exponent. Our argument relies on properties of a deformation map of the reals induced by the Tsallis entropy, and its conclusion agrees with all currently known results.
Parsing a Sequence of Qubits

We develop a theoretical framework for frame synchronization, also known as block synchronization, in the quantum domain, which makes it possible to attach classical and quantum metadata to quantum information over a noisy channel even when the information source and sink are framewise asynchronous. This eliminates the need of frame synchronization at the hardware level and allows for parsing qubit sequences during quantum information processing. Our framework exploits binary constant-weight codes that are self-synchronizing. Possible applications may include asynchronous quantum communication such as a self-synchronizing quantum network where one can hop into the channel at any time, catch the next coming quantum information with a label indicating the sender, and reply by routing her quantum information with control qubits for quantum switches all without assuming prior frame synchronization between users.
A relative entropy rate method for path space sensitivity analysis of stationary complex stochastic dynamics

We propose a new sensitivity analysis methodology for complex stochastic dynamics based on the relative entropy rate. The method becomes computationally feasible at the stationary regime of the process and involves the calculation of suitable observables in path space for the relative entropy rate and the corresponding Fisher information matrix. The stationary regime is crucial for stochastic dynamics and here allows us to address the sensitivity analysis of complex systems, including examples of processes with complex landscapes that exhibit metastability, non-reversible systems from a statistical mechanics perspective, and high-dimensional, spatially distributed models. All these systems exhibit, typically non-Gaussian stationary probability distributions, while in the case of high-dimensionality, histograms are impossible to construct directly. Our proposed methods bypass these challenges relying on the direct Monte Carlo simulation of rigorously derived observables for the relative entropy rate and Fisher information in path space rather than on the stationary probability distribution itself. We demonstrate the capabilities of the proposed methodology by focusing here on two classes of problems: (a) Langevin particle systems with either reversible (gradient) or non-reversible (non-gradient) forcing, highlighting the ability of the method to carry out sensitivity analysis in non-equilibrium systems; and, (b) spatially extended kinetic Monte Carlo models, showing that the method can handle high-dimensional problems.
Gauge-assisted technicolor?

It is well known that technicolor models in which the electroweak symmetry is broken by QCD-like strong dynamics at the TeV scale generally predict unacceptably large corrections to low-energy observables. We investigate the models of electroweak symmetry breaking by strong dynamics in which the gauge symmetry is extended to include an arbitrary number of additional SU(2) and U(1) factors. This class of models includes the deconstructed version of the recently proposed five-dimensional ``Higgsless'' scenario. We conclude that the additional structure present in these theories does not suppress the effects of strongly coupled short-distance physics on the precision electroweak observables. In particular, the possibility that the symmetry breaking is due to QCD-like dynamics is still strongly disfavored by data.
WANDERING STARS: AN ORIGIN OF ESCAPED POPULATIONS

We demonstrate that stars beyond the virial radii of galaxies may be generated by the gravitational impulse received by a satellite as it passes through the pericenter of its orbit around its parent. These stars may become energetically unbound (escaped stars), or may travel to further than a few virial radii for longer than a few Gyr, but still remain energetically bound to the system (wandering stars). Larger satellites (10%-100% the mass of the parent), and satellites on more radial orbits are responsible for the majority of this ejected population. Wandering stars could be observable on Mpc scales via classical novae, and on 100 Mpc scales via Type Ia supernova. The existence of such stars would imply a corresponding population of barely bound, old, high-velocity stars orbiting the Milky Way, generated by the same physical mechanism during the Galaxy's formation epoch. Sizes and properties of these combined populations should place some constraints on the orbits and masses of the progenitor objects from which they came, providing insight into the merging histories of galaxies in general and the Milky Way in particular.
Relaxation to a Perpetually Pulsating Equilibrium

Paper in honour of Freeman Dyson on the occasion of his 80th birthday. NormalN-body systems relax to equilibrium distributions in which classical kinetic energy components are 1/2kT, but, when inter-particle forces are an inverse cubic repulsion together with a linear (simple harmonic) attraction, the system pulsates for ever. In spite of this pulsation in scale,r(t), other degrees of freedom relax to an ever-changing Maxwellian distribution. With a new time, τ, defined so thatr 2d/dt = d/dτ it is shown that the remaining degrees of freedom evolve with an unchanging reduced Hamiltonian. The distribution predicted by equilibrium statistical mechanics applied to the reduced Hamiltonian is an ever-pulsating Maxwellian in which the temperature pulsates liker -2. Numerical simulation with 1000 particles demonstrate a rapid relaxation to this pulsating equilibrium.
VLBI Polarimetry of 177 Sources from the Caltech-Jodrell Bank Flat-Spectrum Survey

We present Very Long Baseline Array observations and a statistical analysis of 5 GHz VLBI polarimetry data from 177 sources in the Caltech-Jodrell Bank Flat-Spectrum (CJF) survey. The CJF survey, a complete, flux density-limited sample of 293 extragalactic radio sources, gives us the unique opportunity to compare a broad range of source properties for quasars, galaxies, and BL Lacertae objects. We focus primarily on jet properties, specifically, the correlation between the jet axis angle and the polarization angle in the core and jet. A strong correlation is found for the electric vector polarization angle in the cores of quasars to be perpendicular to the jet axis. Contrary to previous claims, no correlation is found between the jet polarization angle and the jet axis in either quasars or BL Lac objects. With this large, homogeneous sample we are also able to investigate cosmological issues and active galactic nucleus evolution.
Dimensional Regularization and Nuclear Potentials

It is shown how nucleon-nucleon potentials can be defined in N dimensions, using dimensional regularization to continue amplitudes. This provides an easy way to separate out contact (δ-function) terms arising from renormalization. An example is worked out several ways for the case of two-scalar particles exchanged between nucleons, which involves a very simple loop calculation. This leads to a Feynman-parameterized representation for the nucleon–nucleon potential. Alternately, a dispersion representation can be developed leading to a different, though equivalent, form.
Gravitons to Photons { attenuation of gravitational waves

In this essay, we examine the response of an Unruh–DeWitt (UD) detector (a quantum two-level system) to a gravitational wave background. The spectrum of the UD detector is of the same form as some scattering processes or three body decays such as muon-electron scattering or muon decay. Based on this similarity, we propose that the UD detector response implies a “decay” or attenuation of gravitons, G, into photons, γ, via G + G → γ + γ or G → γ + γ + G. Over large distances such a decay/attenuation may have consequences in regard to the detection of gravitational waves.
X-Ray Emission from Young Stellar Objects in the epsilon Chamaeleontis Group: The Herbig Ae Star HD 104237 and Associated Low-Mass Stars

We present Chandra HETGS observations of the Herbig Ae star HD 104237 and the associated young stars comprising lower mass stars, in the 0.15-1.75 -->M? mass range, in their pre-main-sequence phase. The brightest X-ray source in the association is the central system harboring the Herbig Ae primary and a K3 companion. Its X-ray variability indicates modulation possibly on timescales of the rotation period of the Herbig Ae star, and this would imply that the primary significantly contributes to the overall emission. The spectrum of the Herbig Ae+K3 system shows a soft component significantly more pronounced than in other K-type young stars. This soft emission is reminiscent of the unusually soft spectra observed for the single Herbig Ae stars HD 163296 and AB Aur, and therefore we tentatively attribute it to the Herbig Ae of the binary system. The HETGS spectrum shows strong emission lines corresponding to a wide range of plasma temperatures. The He-like triplet of Mg XI and Ne IX suggests the presence of plasma at densities of about 1012 cm?3, possibly indicating an accretion-related X-ray production mechanism. The analysis of the zeroth-order spectra of the other sources indicates X-ray emission characteristics typical of pre-main-sequence stars of similar spectral type, with the exception of the T Tauri HD 104237-D, whose extremely soft emission is very similar to the emission of the classical T Tauri star TW Hya and suggests X-ray production by shocked accreting plasma.
SUSY INTO DARKNESS: HEAVY SCALARS IN THE CMSSM

A survey of the mSUGRA/CMSSM parameter space is presented. The viable regions of the parameter space which satisfy standard experimental constraints are identified and discussed. These constraints include a 124–127 GeV mass for the lightest CP-even Higgs and the correct relic density for cold dark matter. The superpartner spectra corresponding to these regions fall within the well-known hyperbolic branch and are found to possess sub-TeV neutralinos and charginos, with mixed Bino/Higgsino LSP's with 200–800 GeV masses. In addition, the models possess ~3–4 TeV gluino masses and heavy squarks and sleptons with masses . Spectra with a Higgs mass mh ≅125 GeV and a relic density 0.105 ≤ Ωχ0 h2 ≤ 0.123 are found to require EWFT at around the one-percent level, while those spectra with a much lower relic density require EWFT of only a few percent. Moreover, the spin-independent neutralino–proton direct detection cross-sections are found to be below or within the XENON100 2σ limit and should be experimentally accessible now or in the near future. Finally, it is pointed out that the supersymmetry breaking soft terms corresponding to these regions of the mSUGRA/CMSSM parameter space (m0 ∝ m1/2 with and A0 = -m1/2) may be obtained from general flux-induced soft terms in Type IIB flux compactifications with D3 branes.
THE ORBITAL PERIOD OF SCORPIUS X-1

The orbital period of Sco X-1 was first identified by Gottlieb et al. While this has been confirmed on multiple occasions, this work, based on nearly a century of photographic data, has remained the reference in defining the system ephemeris ever since. It was, however, called into question when Vanderlinde et al. claimed to find the one-year alias of the historical period in RXTE/All-Sky Monitor data and suggested that this was the true period rather than that of Gottlieb et al. We examine data from the All Sky Automated Survey (ASAS) spanning 2001-2009. We confirm that the period of Gottlieb et al. is in fact the correct one, at least in the optical, with the one-year alias strongly rejected by these data. We also provide a modern time of minimum light based on the ASAS data.
Flatland electrons in high magnetic fields

This paper provides a review of developments in the physics of two-dimensional electron systems in perpendicular magnetic fields.
Numerical Solutions for the Orbital Motion of the Solar System over the Past 100 Myr: Limits and New Results

I report results from accurate numerical integrations of Solar System orbits over the past 100Myr with the integrator package HNBody. The simulations used different integrator algorithms, step sizes, initial conditions, and included effects from general relativity, different models of the Moon, the Sun's quadrupole moment, and up to sixteen asteroids. I also probed the potential effect of a hypothetical Planet 9, using one set of possible orbital elements. The most expensive integration (Bulirsch-Stoer) required 4~months wall-clock time with a maximum relative energy error <~3e{-13}. The difference in Earth's eccentricity (DeE) was used to track the difference between two solutions, considered to diverge at time tau when max|DeE| irreversibly crossed ~10\% of mean eE (~0.028x0.1). The results indicate that finding a unique orbital solution is limited by initial conditions from current ephemerides and asteroid perturbations to ~54Myr. Bizarrely, the 4-month Bulirsch-Stoer integration and a symplectic integration that required only 5~hours wall-clock time (12-day time step, Moon as a simple quadrupole perturbation), agree to ~63Myr. Internally, such symplectic integrations are remarkably consistent even for large time steps, suggesting that the relationship between time step and tau is not a robust indicator for the absolute accuracy of symplectic integrations. The effect of a hypothetical Planet~9 on DeE becomes discernible at ~65Myr. Using tau as a criterion, the current state-of-the-art solutions all differ from previously published results beyond ~50Myr. I also conducted an eigenmode analysis, which provides some insight into the chaotic nature of the inner Solar System. The current study provides new orbital solutions for applications in geological studies.
Exploring the propagation of relativistic quantum wavepackets in the trajectory-based formulation

In the context of nonrelativistic quantum mechanics, Gaussian wavepacket solutions of the time-dependent Schrodinger equation provide useful physical insight. This is not the case for relativistic quantum mechanics, however, for which both the Klein-Gordon and Dirac wave equations result in strange and counterintuitive wavepacket behaviors, even for free-particle Gaussians. These behaviors include zitterbewegung and other interference effects. As a potential remedy, this paper explores a new trajectory-based formulation of quantum mechanics, in which the wavefunction plays no role [Phys. Rev. X, 4, 040002 (2014)]. Quantum states are represented as ensembles of trajectories, whose mutual interaction is the source of all quantum effects observed in nature—suggesting a "many interacting worlds" interpretation. It is shown that the relativistic generalization of the trajectory-based formulation results in well-behaved free-particle Gaussian wavepacket solutions. In particular, probability density is positive and well-localized everywhere, and its spatial integral is conserved over time—in any inertial frame. Finally, the ensemble-averaged wavepacket motion is along a straight line path through spacetime. In this manner, the pathologies of the wave-based relativistic quantum theory, as applied to wavepacket propagation, are avoided.
Cold ion-atom chemistry driven by spontaneous radiative relaxation: a case study for the formation of the YbCa+ molecular ion

Using both quantum and semi-classical methods, we calculate the rates for radiative association and charge transfer in cold collisions of Yb+ with Ca. We demonstrate the fidelity of the local optical potential method in predictions for the total radiative relaxation rates. We find a large variation in the isotope dependence of the cross sections at ultra-cold gas temperatures. However, at cold temperatures, 1 mK < T < 1 K, the effective spontaneous radiative rates for the different isotopes share a common value of about 1.5 × 10−15 cm3 s−1. It is about five orders of magnitude smaller than the chemical reaction rate measured in Rellergert et al (2011 Phys. Rev. Lett. 107 243201).
PRECISE INFRARED RADIAL VELOCITIES FROM KECK/NIRSPEC AND THE SEARCH FOR YOUNG PLANETS

We present a high-precision infrared radial velocity (RV) study of late-type stars using spectra obtained with NIRSPEC at the W. M. Keck Observatory. RV precisions of 50 m s{sup -1} are achieved for old field mid-M dwarfs using telluric features for wavelength calibration. Using this technique, 20 young stars in the {beta} Pic (age {approx} 12 Myr) and TW Hya (age {approx} 8 Myr) Associations were monitored over several years to search for low-mass companions; we also included the chromospherically active field star GJ 873 (EV Lac) in this survey. Based on comparisons with previous optical observations of these young active stars, RV measurements at infrared wavelengths mitigate the RV noise caused by star spots by a factor of {approx}3. Nevertheless, star spot noise is still the dominant source of measurement error for young stars at 2.3 {mu}m, and limits the precision to {approx}77 m s{sup -1} for the slowest rotating stars (v sin i 12 km s{sup -1}). The observations reveal both GJ 3305 and TWA 23 to be single-lined spectroscopic binaries; in the case of GJ 3305, the motionmore » is likely caused by its 0.''09 companion, identified after this survey began. The large amplitude, short-timescale variations of TWA 13A are indicative of a hot Jupiter-like companion, but the available data are insufficient to confirm this. We label it as a candidate RV variable. For the remainder of the sample, these observations exclude the presence of any 'hot' (P < 3 days) companions more massive than 8 M{sub Jup} and any 'warm' (P < 30 days) companions more massive than 17 M{sub Jup}, on average. Assuming an edge-on orbit for the edge-on disk system AU Mic, these observations exclude the presence of any hot Jupiters more massive than 1.8 M{sub Jup} or warm Jupiters more massive than 3.9 M{sub Jup}.« less
Quantitative argument summarization and beyond: Cross-domain key point analysis.

When summarizing a collection of views, arguments or opinions on some topic, it is often desirable not only to extract the most salient points, but also to quantify their prevalence. Work on multi-document summarization has traditionally focused on creating textual summaries, which lack this quantitative aspect. Recent work has proposed to summarize arguments by mapping them to a small set of expert-generated key points, where the salience of each key point corresponds to the number of its matching arguments. The current work advances key point analysis in two important respects: first, we develop a method for automatic extraction of key points, which enables fully automatic analysis, and is shown to achieve performance comparable to a human expert. Second, we demonstrate that the applicability of key point analysis goes well beyond argumentation data. Using models trained on publicly available argumentation datasets, we achieve promising results in two additional domains: municipal surveys and user reviews. An additional contribution is an in-depth evaluation of argument-to-key point matching models, where we substantially outperform previous results.
The Kinematics of the Outer Halo of M87

Radial velocities are presented for a new sample of globular clusters in the outer halo of M87 at a distance of 300''–540'' (24–43 kpc) from the center of this galaxy. These are used to augment our previously published data, and an analysis of the rotation and velocity dispersion of the M87 globular cluster system is carried out. The rotation is ~300 km s-1 at R = 32 kpc, at which point the velocity dispersion is also still quite high, ~450 km s-1. The high rotation is interesting. The outer halo of M87 is, as was found in our previous kinematic analysis, very massive.
The Cost to Break SIKE: A Comparative Hardware-Based Analysis with AES and SHA-3.

This work presents a detailed study of the classical security of the post-quantum supersingular isogeny key encapsulation (SIKE) protocol using a realistic budget-based cost model that considers the actual computing and memory costs that are needed for cryptanalysis. In this effort, we design especially-tailored hardware accelerators for the time-critical multiplication and isogeny computations that we use to model an ASIC-powered instance of the van Oorschot-Wiener (vOW) parallel collision search algorithm. We then extend the analysis to AES and SHA-3 in the context of the NIST post-quantum cryptography standardization process to carry out a parameter analysis based on our cost model. This analysis, together with the state-of-the-art quantum security analysis of SIKE, indicates that the current SIKE parameters offer higher practical security than currently believed, closing an open issue on the suitability of the parameters to match NIST’s security levels. In addition, we explore the possibility of using significantly smaller primes to enable more efficient and compact implementations with reduced bandwidth. Our improved cost model and analysis can be applied to other cryptographic settings and primitives, and can have implications for other post-quantum candidates in the NIST process.
Extremes of locally stationary Gaussian and chi fields on manifolds

Abstract Depending on a parameter h ∈ ( 0 , 1 ] , let { X h ( t ) , t ∈ M h } be a class of centered Gaussian fields indexed by compact manifolds M h with positive reach. For locally stationary Gaussian fields X h , we study the asymptotic excursion probabilities of X h on M h . Two cases are considered: (i) h is fixed and (ii) h → 0 . These results are also extended to obtain the limit behaviors of the extremes of locally stationary χ -fields on manifolds.
Probabilistic Foundations of Spatial Mean-Field Models in Ecology and Applications

Deterministic models of vegetation often summarize, at a macroscopic scale, a multitude of intrinsically random events occurring at a microscopic scale. We bridge the gap between these scales by de...
Robust autocalibrated structured low-rank EPI ghost correction.

Purpose We propose and evaluate a new structured low-rank method for echo-planar imaging (EPI) ghost correction called Robust Autocalibrated LORAKS (RAC-LORAKS). The method can be used to suppress EPI ghosts arising from the differences between different readout gradient polarities and/or the differences between different shots. It does not require conventional EPI navigator signals, and is robust to imperfect autocalibration data. Methods Autocalibrated LORAKS is a previous structured low-rank method for EPI ghost correction that uses GRAPPA-type autocalibration data to enable high-quality ghost correction. This method works well when the autocalibration data are pristine, but performance degrades substantially when the autocalibration information is imperfect. RAC-LORAKS generalizes Autocalibrated LORAKS in two ways. First, it does not completely trust the information from autocalibration data, and instead considers the autocalibration and EPI data simultaneously when estimating low-rank matrix structure. Second, it uses complementary information from the autocalibration data to improve EPI reconstruction in a multi-contrast joint reconstruction framework. RAC-LORAKS is evaluated using simulations and in vivo data, including comparisons to state-of-the-art methods. Results RAC-LORAKS is demonstrated to have good ghost elimination performance compared to state-of-the-art methods in several complicated EPI acquisition scenarios (including gradient-echo brain imaging, diffusion-encoded brain imaging, and cardiac imaging). Conclusions RAC-LORAKS provides effective suppression of EPI ghosts and is robust to imperfect autocalibration data.
Beyond Reynolds: A Constraint-Driven Approach to Cluster Flocking

In this paper, we present an original set of flocking rules using an ecologically-inspired paradigm for control of multi-robot systems. We translate these rules into a constraint-driven optimal control problem where the agents minimize energy consumption subject to safety and task constraints. We prove several properties about the feasible space of the optimal control problem and show that velocity consensus is an optimal solution. We also motivate the inclusion of slack variables in constraint-driven problems when the global state is only partially observable by each agent. Finally, we analyze the case where the communication topology is fixed and connected and prove that our proposed flocking rules achieve velocity consensus.
On fast pattern formation by autonomous robots

Abstract We consider the fundamental problem of arranging a set of n autonomous robots (points) on a real plane according to an arbitrary given pattern. Each robot operates in a, largely oblivious, look-compute-move step. We measure the time complexity of our algorithms in “epochs,” which denotes the minimum time interval in which every robot performs at least one look-compute-move step. We present a framework for the pattern formation problem in which leader election is key. Where n robots can elect a leader in T LE ( n ) epochs, we show that pattern formation can be solved in O ( T LE ( n ) ) epochs on the semi-synchronous model using robots that either are transparent (that is, the classical oblivious robots model where complete visibility is guaranteed at all times) or have lights with a constant number of colors (that is, the robots with lights model where robots are not transparent but the colors of the lights are persistent between steps). We also prove that, for some cases, the O ( T LE ( n ) ) epochs are optimal on the semi-synchronous model. Our results on the semi-synchronous model indicate that transparency and lights compensate for each other in the pattern formation problem. The proposed method runs in O ( T L E ( n ) + log ⁡ n ) epochs on the asynchronous model of robots with lights. This translates to an algorithm on the asynchronous model that runs in O ( log ⁡ n ) randomized epochs with high probability. Our algorithms do not assume agreement on direction or orientation of the robots such as global coordinate system, chirality, or one-axis agreement. Robot motions are rigid in the sense that when a robot moves it reaches its destination point at the completion of that move. The proposed algorithms are randomized and guarantee the claimed time bounds with high probability. The randomization is used only for leader election. Finally, we provide lower bounds regarding optimality of our results as well as impossibility of designing an asynchronous algorithm in the classical model.
BMS symmetry via AdS/CFT

With a view to understanding extended-BMS symmetries in the framework of the AdS4/CFT3 correspondence, asymptotically AdS geometries are constructed with null impulsive shockwaves involving a discontinuity in superrotation parameters. The holographic dual is proposed to be a two-dimensional Euclidean defect conformal field localized on a particular timeslice in a three-dimensional conformal field theory on de Sitter spacetime. The defect conformal field theory generates a natural action of the Virasoro algebra. The large radius of curvature limit l → ∞ yields spacetimes with nontrivial extended-BMS charges corresponding to a single set of Virasoro charges.
Structural insights into photoactivation of plant Cryptochrome-2

Cryptochromes (CRYs) are evolutionarily conserved photoreceptors that mediate various light-induced responses in bacteria, plants, and animals. Plant cryptochromes govern a variety of critical growth and developmental processes including seed germination, flowering time and entrainment of the circadian clock. CRY’s photocycle involves reduction of their flavin adenine dinucleotide (FAD)-bound chromophore, which is completely oxidized in the dark and semi to fully reduced in the light signaling-active state. Despite the progress in characterizing cryptochromes, important aspects of their photochemistry, regulation, and light-induced structural changes remain to be addressed. In this study, we determine the crystal structure of the photosensory domain of Arabidopsis CRY2 in a tetrameric active state. Systematic structure-based analyses of photo-activated and inactive plant CRYs elucidate distinct structural elements and critical residues that dynamically partake in photo-induced oligomerization. Our study offers an updated model of CRYs photoactivation mechanism as well as the mode of its regulation by interacting proteins. Palayam, Ganapathy, Guercio et al. determine the crystal structure of the photosensory domain of Arabidopsis Cryptochrome-2 (CRY2) in a tetrameric active state, identifying critical residues that participate in photo-induced oligomerization of CRY2. This study offers an updated model of CRY’s photoactivation mechanism.
Maximal subgroup growth of some metabelian groups

Let G be a finitely generated group, and let m n ( G ) denote the number of maximal subgroups of G of index n. An upper bound is given for the degree of maximal subgroup growth of all polycyclic me...
Stress-Induced Birefringence of Swollen Polymer Networks

Abstract Stress-optical coefficients have been determined for lightly crosslinked samples of cis- and trans-polyisoprene, swollen to a high degree in a variety of nonpolar solvents. A strong dependence on the geometrical asymmetry of the solvent molecule has been observed. Solvents with long, straight molecules gave large values of the stress-optical coefficient whereas those with compact, symmetrical molecules gave minimum values. This effect is attributed to short-range orientational order, due to packing effects in a molecularly anisotropic medium. The large values obtained for unswollen polymers correspond to those in relatively anisotropic solvents, and thus indicate a significant degree of local order in the bulk phase. The minimum values are interpreted, using calculated optical anisotropies of chain repeat units, as measures of the stiffness of isolated chains.
Numerical Method for Disordered Quantum Phase Transitions in the Large-N Limit

We develop an efficient numerical method to study the quantum critical behavior of disordered systems with order-parameter symmetry in the large-N limit. It is based on the iterative solution of the large-N saddle-point equations combined with a fast algorithm for inverting the arising large sparse random matrices. As an example, we consider the superconductor-metal quantum phase transition in disordered nanowires. We study the behavior of various observables near the quantum phase transition. Our results agree with recent renormalization group predictions, i.e., the transition is governed by an infinite-randomness critical point, accompanied by quantum Griffiths singularities. In contrast to the existing numerical approach to this problem, our method gives direct access to the temperature dependencies of observables. Moreover, our algorithm is highly efficient because the numerical effort for each iteration scales linearly with the system size. This allows us to study larger systems, with up to 1024 sites, than previous methods. We also discuss generalizations to higher dimensions and other systems including the itinerant antiferromagnetic transitions in disordered metals.
Corporate Tax: The Agony and the Ecstasy

This article focuses on various corporate tax rules that just do not seem to make sense or, at the very least, are more complex than seems really necessary. These problems are caused by Congress's incremental and piecemeal approach to formulation of corporate tax, sometimes not even dovetailing the increments with the current statutory rules that are left unamended; political considerations, e.g., the recent legislation resulting in a partial exclusion of dividends paid to humans, which was a political compromise and is not a carefully constructed set of rules; the opening and closing of loopholes as the private sector constantly searches for weaknesses in the current tax system, resulting in Byzantine concoctions against which the government responds with complex anti avoidance rules; and the inherent complexity of corporate structures and transactions, which requires a degree of complexity in the tax law. In particular, the article focuses on the multitudinous corporate control tests; the arcane, constructive stock ownership tests; the lack of uniform rules for passthrough entities; and a few of the many erratic rules regarding tax-free organizations. The article makes the following common sense proposals. Congress should dovetail new legislation with the current code. It should synthesize the corporate control tests into a basic 80% test and a basic 50% test. It should synthesize all of the constructive stock ownership rules into one rule. It should settle on one set of eligibility requirements and one set of tax consequences for passthrough entities. And it should settle on a uniform consideration requirement for every type of acquisitive reorganization.
We the People: John Locke, Collective Constitutional Rights, and Standing to Challenge Government Action

As the Constitution's Preamble demonstrates, sovereignty in the United States actually resides in the people, not in government. John Locke, perhaps the most influential political philosopher for the Framers, made clear that properly constituted government was a trustee for the people, and James Madison echoed that sentiment. The Supreme Court's standing doctrine, however, often makes it impossible for the people to call the government-as-trustee to account. This article suggests that constitutional rights are held individually, to be sure, but also collectively by the body politic. Scholars and courts have repeatedly recognized collective interests, but most often evaluate them when they appear to conflict with individual rights. The article suggests that in cases where the issue is whether government violated the Constitution, individual and collective interests, far from being opposed, actually coincide. In a significant subclass of those cases, standing doctrine makes impossible judicial protection of collective interests and judicial insistence that government operate within proper bounds. The effect is that certain constitutional provisions effectively exist only at the whim and during the good will of the government. The existence and recognition of collective rights require a modification of standing doctrine to allow the courts to protect such rights, but without creating universal standing, which would threaten the courts with a tidal wave of litigation from officious intermeddlers.
Estimates of statewide and nationwide carbon dioxide emission reductions and their costs from Cash for Clunkers

Vehicle scrappage programs which provide private owners with inducements to scrap their older, less-fuel efficient vehicles offer the promise to both increase consumer spending on private vehicles and reduce greenhouse gas emissions. The Cash for Clunkers program enacted in 2009 is the first nationwide incarnation of such a program in the United States where past programs have been confined to specific regions and states. While measuring the success of such programs in terms of sales is straightforward, measuring their success in terms of greenhouse gas emission reductions is not. Much of the difficulty in estimating these reductions relates to projecting how private vehicle owners will use their newer, more fuel efficient vehicles. Using cross-sectional data on how the trade-in vehicles were typically used as well as projected usage increases due to the rebound effect (improvements in fuel efficiency cause more usage), this study estimates emission reductions and their costs for two different vehicle usage scenarios. Estimates from the two scenarios indicate that the nationwide effects of the Cash for Clunkers program on carbon dioxide emissions are modest, at best. Exploration of statewide carbon dioxide emission reductions and costs from Cash for Clunkers indicates that, as suggested by the literature, the environmental benefits of vehicle scrappage programs are limited.
Calibrated Commitment: The Legal Treatment of Marriage and Cohabitation

Increase in and greater acceptance of cohabitation without marriage raise the question whether law should provide comparable benefits to married and unmarried partners. Proponents of such a development argue that a preference for marriage is compatible with contemporary emphasis on individual choice in intimate matters. On this view, law should focus on the substance of a couple's relationship rather than privilege those partnerships characterized by a formal legal tie. Opponents argue that marriage should continue to have privileged status in the law, because blurring the line between married and unmarried partners would undermine marriage as an important social institution. The result, the argument goes, would be less cultural reinforcement of the value of durable commitment in intimate relationships. This article suggests that neither categorical extension nor denial of marriage-like benefits to cohabiting partners is appropriate. With respect to certain issues, the state's interest in creating incentives or expressing values that favor marriage should permit the law to restrict benefits to spouses. In other cases, these purposes may be outweighed by more important considerations. This means that making decisions about the respects in which unmarried partners should enjoy legal treatment similar to that afforded spouses requires sensitivity to the interests at stake in each instance. This article examines a variety of benefits, and suggests some general rules of thumb about when the legal claims of cohabitors should be honored as if made by spouses.
Religious Purpose, Inerrancy, and the Establishment Clause

According to the much-contested "purpose" requirement of the Supreme Court's Establishment Clause doctrine, laws must be grounded on secular as opposed to religious purposes. This article advances a normative argument concerning how this requirement should be construed. The author distinguishes between different types of religious purposes and different types of religious beliefs. Most importantly, he distinguishes between "inerrant" religious beliefs, which are characterized by a certain type of closed-mindedness, and "dialogic" religious beliefs, which are not. After developing a suggested analytical framework, the author applies his approach to the issues of school prayer, evolution, and abortion. He then confront various objections that might be made to his argument, including the claim that all religious beliefs must he treated alike.
Competition and confidentiality: Signaling quality in a duopoly when there is universal private information

Abstract We model non-cooperative signaling by two firms that compete over a continuum of consumers, assuming each consumer has private information about the intensity of her preferences for the firms' respective products and each firm has private information about its own product's quality. We characterize a symmetric separating equilibrium in which each firm's price reveals its respective product quality. We show that the equilibrium prices, the difference between those prices, the associated outputs, and profits are all increasing functions of the ex ante probability of high safety. If horizontal product differentiation is sufficiently great then equilibrium prices and profits are higher under incomplete information about quality than if quality were commonly known. Thus, while signaling imposes a distortionary loss on a monopolist using price to signal quality, duopolists may benefit from the distortion as it can reduce competition. Finally, average quality is lower since signaling quality redistributes demand towards low-quality firms.
Bayesian Analysis of the Censored Regression Model with an AEPD Error Term

We present the censored regression model with the error term following the asymmetric exponential power distribution. We propose three Markov chain Monte Carlo (MCMC) algorithms: the first one uses the probability integral transformation; the second one uses a combination of the probability integral transformation and random walk draws; while the third one uses random walk draws. Using simulated data we compare the performance of the three MCMC algorithms. Then we compare the posterior means, or Bayes estimates, with maximum likelihood estimates. We estimate the stock option portion of executive compensation as an example of the empirical application.
Investors’ Perceptions of Auditors’ Economic Dependence on the Client Post-SOX Evidence

The authors revisit the client importance and auditor independence debate, and investigate whether investors’ perceptions of the auditor’s economic dependence has changed since the passage of the Sarbanes–Oxley Act of 2002 (SOX). Client importance is measured as the proportion of client nonaudit service fees, audit fees, or total fees to the total audit office revenue. Consistent with their hypothesis, they find a significant decrease in the association between both nonaudit services (NAS) and total fees, and the cost of equity from the pre- to the post-SOX period, indicating that investors’ concerns over auditor independence have changed in the post-SOX period. In addition, the authors find some evidence of a positive and significant association between both audit fees (2003) and total fees (2004), and cost of equity in the post-SOX period. Overall, these results indicate that the independence requirements in SOX and/or the heightened litigation environment post-SOX have, to some extent, mitigated but no...
Determinants of business cycle comovement: a robust analysis

Abstract This paper investigates the determinants of business cycle comovement between countries. Our dataset includes over 100 countries, both developed and developing. We search for variables that are “robust” in explaining comovement, using the approach of Leamer (Amer. Econom. Rev. 73 (1983) 31). Variables considered are (i) bilateral trade between countries; (ii) total trade in each country; (iii) sectoral structure; (iv) similarity in export and import baskets; (v) factor endowments; and (vi) gravity variables. We find that bilateral trade is robust. However, two variables that the literature has argued are important for business cycles—industrial structure and currency unions—are found not to be robust.
Sarbanes-Oxley and corporate risk-taking

Abstract We empirically examine whether risk-taking by publicly traded US companies declined significantly after adoption of the Sarbanes-Oxley Act of 2002 (SOX). Several provisions of SOX are likely to discourage risk-taking, including an expanded role for independent directors, an increase in director and officer liability, and rules related to internal controls. We find several measures of risk-taking decline significantly for US versus non-US firms after SOX. The magnitudes of the declines are related to several firm characteristics, including pre-SOX board structure, firm size, and R&D expenditures. The evidence is consistent with the proposition that SOX discourages risk-taking by public US companies.
Can Package Size Accelerate Usage Volume

Packaging influences usage behavior long after it has influenced purchase. Managers of consumer packaged goods and public policy officials have, therefore, questioned whether a package's size influ...
The Arithmetic of Arsenic

What does cost-benefit mean, or do, in actual practice? When agencies are engaging in cost-benefit balancing, what are the interactions among law, science, and economics? This Article attempts to answer that question by exploring, in some detail, the controversy over EPA’s proposed regulation of arsenic in drinking water. The largest finding is that science often can produce only “benefit ranges,” and wide ones at that. With reasonable assumptions based on the existing science data, the proposed arsenic regulation can be projected to save as few as 0 lives and as many as 112. With reasonable assumptions, the monetized benefits of the regulation can range from $0 to $560 million. In these circumstances, there is no obviously right decision for government agencies to make. These points have numerous implications for lawyers and courts, suggesting the ease of bringing legal challenges, on grounds specified here, and the importance of judicial deference in the face of scientific uncertainty. There are also policy implications. Agencies should be given the authority to issue more targeted, cost-effective regulations. They should also be required to accompany the cost-benefit analysis with an effort to identify the winners and losers, so as to see if poor people are mostly hurt or mostly helped. Americans may disagree about a lot of things, but arsenic isn’t one of them. When you turn on the kitchen sink, you ought to be able to drink what comes out, without worrying about being poisoned.1 “What we know is a drop, what we do not know—an ocean” (Isaac Newton). In spite of significant gains in knowledge, we are still moving mainly in the dark when dealing with the quantitative importance of risk factors in *Karl N. Llewellyn Distinguished Service Professor of Jurisprudence, Law School and Department of Political Science, University of Chicago. I am grateful to Laura Warren for outstanding research assistance and to Jonathan Baron, Robert Hahn, Lisa Heinzerling, Eric Posner, Richard Posner, and participants in a work-in-progress lunch at the Universty of Chicago Law School for valuable suggestions on a previous draft. 1 Rep. David Bonior, quoted in the Chicago Tribune, July 28, 2001, p. 1.
Testing for Linear and Nonlinear Causality between Crude Oil Price Changes and Stock Market Returns

This paper examines both the linear and nonlinear causal relationships between crude oil price changes and stock market returns for the United States. In particular, the study applied a battery of unit root tests to ascertain the time series properties of crude oil price changes and stock market returns. The linear and nonlinear causality tests were conducted through the standard VAR and the M-G frameworks, respectively. The results from both the linear and nonlinear unit root tests indicate that crude oil price changes and stock market returns are level stationary. The results from the standard VAR model provide evidence of bidirectional causality between crude oil price changes and stock market returns. The results from the M-G causality test support the finding of nonlinear bidirectional causality between crude oil price changes and stock market returns.