W-graph ideals

We introduce a concept of a W-graph ideal in a Coxeter group. The main goal of this paper is to describe how to construct a W-graph from a given W-graph ideal. The principal application of this idea is in type A, where it provides an algorithm for the construction of W-graphs for Specht modules.Comment: 25 page

The Military Career of James Gettys

James Gettys was a Federalist, tried and true. From his role in the American Revolution to his final position as Vice Brigadier General during the War of 1812, James understood the necessity for “we the people” to remain united as one, power in numbers. He lived that way, worked that way, and built his town on that premise. Like most of the frontiersmen of his time, his life was difficult, and his rise to the top was not always met with valor. Much like his father, Samuel, James Gettys fought for everything he had, and his attainments were well earned. Until recently, discussion of James Gettys’ military career began with his 1781 role as a Cornet in a Light Horsemen of York County. While any role in the Revolutionary War was beneficial, his appeared fairly insignificant, as a Cornet was a lower ranked officer, and Gettys’ unit was never activated.1 Seemingly odd given his numerous promotions within the militia, James appeared to witness the fighting safely on the sidelines. New research, however, reveals, that this version of events is not entirely accurate. This article reviews that new evidence and narrates the postwar Revolutionary War life of Gettysburg’s founding father

Cosmology with Peculiar Velocities: Observational Effects

In this paper we investigate how observational effects could possibly bias cosmological inferences from peculiar velocity measurements. Specifically, we look at how bulk flow measurements are compared with theoretical predictions. Usually bulk flow calculations try to approximate the flow that would occur in a sphere around the observer. Using the Horizon Run 2 simulation we show that the traditional methods for bulk flow estimation can overestimate the magnitude of the bulk flow for two reasons: when the survey geometry is not spherical (the data do not cover the whole sky), and when the observations undersample the velocity distributions. Our results may explain why several bulk flow measurements found bulk flow velocities that seem larger than those expected in standard {\Lambda}CDM cosmologies. We recommend a different approach when comparing bulk flows to cosmological models, in which the theoretical prediction for each bulk flow measurement is calculated specifically for the geometry and sampling rate of that survey. This means that bulk flow values will not be comparable between surveys, but instead they are comparable with cosmological models, which is the more important measure.Comment: 11 pages, 5 figures. Accepted for publication in MNRA

The Achilles Heel of Governance: Critical Capacity Deficits and Their Role in Governance Failures

10.2139/ssrn.24231661-2

Enhancing Policy Capacity for Better Policy Integration: Achieving the Sustainable Development Goals in a Post COVID-19 World

The adoption of the Sustainable Development Goals (SDGs) by the UN, in 2015, established a clear global mandate for greater integrated policymaking, but there has been little consensus on how to achieve them. The COVID-19 pandemic amplified the role of policy capacity in mounting this kind of integrated policy response; however, the relationship between pre- and post-pandemic SDG efforts remains largely unexplored. In this article, we seek to address this gap through a conceptual analysis of policy integration and the capacities necessary for its application to the current SDG situation. Building on the literature on policy design, we define policy integration as the process of effectively reconciling policy goals and policy instruments and we offer a typology of policy integration efforts based on the degree of goal and instrument consistency including: policy harmonization, mainstreaming, coordination, and institutionalization. These forms of policy integration dictate the types of strategies that governments need to adopt in order to arrive at a more coherent policy mix. Following the dimensions of policy capacity by Wu et al. (2015), policy capacities are identified that are critical to ensuring successful integration. This information, thus, contributes to both academic- and policy-related debates on policy integration, by advancing conceptual clarity on the different, and sometimes, diverging concepts used in the field

Standard siren speeds: improving velocities in gravitational-wave measurements of H0

We re-analyse data from the gravitational-wave event GW170817 and its host galaxy NGC 4993 to demonstrate the importance of accurate total and peculiar velocities when measuring the Hubble constant using this nearby standard siren. We show that a number of reasonable choices can be made to estimate the velocities for this event, but that systematic differences remain between these measurements depending on the data used. This leads to significant changes in the Hubble constant inferred from GW170817. We present Bayesian model averaging as one way to account for these differences, and obtain H-0 = 66.8(-9.2)(+13.4) km s(-1)Mpc(-1). Adding additional information on the viewing angle from high-resolution imaging of the radio counterpart refines this to H-0 = 64.8(-7.2)(+7.3) km s(-1) Mpc(-1). During this analysis, we also present an alternative Bayesian model for the posterior on H-0 from standard sirens that works more closely with observed quantities from redshift and peculiar velocity surveys. Our results more accurately capture the true uncertainty on the total and peculiar velocities of NGC 4993 and show that exploring how well different data sets characterize galaxy groups and the velocity field in the local Universe could improve this measurement further. These considerations impact any low-redshift distance measurement, and the improvements we suggest here can also be applied to standard candles like Type Ia supernovae. GW170817 is particularly sensitive to peculiar velocity uncertainties because it is so close. For future standard siren measurements, the importance of this error will decrease as (i) we will measure more distant standard sirens and (ii) the random direction of peculiar velocities will average out with more detections

The Elements of Effective Program Design: A Two-Level Analysis

Politics and Governance221-1

Evaluating bulk flow estimators for CosmicFlows-4 measurements

For over a decade there have been contradictory claims in the literature about whether the local bulk flow motion of galaxies is consistent or in tension with the $\Lambda$CDM model. While it has become evident that systematics affect bulk flow measurements, systematics in the estimators have not been widely investigated. In this work, we thoroughly evaluate the performance of four estimator variants, including the Kaiser maximum likelihood estimator (MLE) and the minimum variance estimator (MVE). We find that these estimators are unbiased, however their precision may be strongly correlated with the survey geometry. Small biases in the estimators can be present leading to underestimated bulk flows, which we suspect are due to the presence of non-linear peculiar velocities. The uncertainty assigned to the bulk flows from these estimators is typically underestimated, which leads to an overestimate of the tension with $\Lambda$CDM. We estimate the bulk flow for the CosmicFlows-4 data and use mocks to ensure the uncertainties are appropriately accounted for. Using the MLE we find a bulk flow amplitude of $408\pm165 \mathrm{km s}^{-1}$ at a depth of $49\, \mathrm{Mpc} h^{-1}$, in reasonable agreement with $\Lambda$CDM. However using the MVE which can probe greater effective depths, we find an amplitude of $428\pm108 \mathrm{km s}^{-1}$ at a depth of $173\, \mathrm{Mpc} h^{-1}$, in tension with the model, having only a 0.11% probability of obtaining a larger $\chi^2$. These measurements appear directed towards the Great Attractor region where more data may be needed to resolve tensions

Can Einstein (rings) surf Gravitational Waves?

How does the appearance of a strongly lensed system change if a gravitational wave is produced by the lens? In this work we address this question by considering a supermassive black hole binary at the center of the lens emitting gravitational waves propagating either colinearly or orthogonally to the line of sight. Specializing to an Einstein ring configuration (where the source, the lens and the observer are aligned), we show that the gravitational wave induces changes on the ring's angular size and on the optical path of photons. The changes are the same for a given pair of antipodal points on the ring, but maximally different for any pair separated by $90^{\circ}$. For realistic lenses and binaries, we find that the change in the angular size of the Einstein ring is dozens of orders of magnitude smaller than the precision of current experiments. On the other hand, the difference in the optical path induced on a photon by a gravitational wave propagating \textit{orthogonally} to the line of sight triggers, at peak strain, time delays in the range $\sim 0.01 - 1$ seconds, making the chance of their detection (and thus the use of Einstein rings as gravitational wave detectors) less hopeless.Comment: v2. Version accepted for publication in the Open Journal of Astrophysics. 8 pages, four figures. Comments are welcome

Faster cosmological analysis with power spectrum without simulations

$$Future surveys could obtain tighter constraints for the cosmological parameters with the galaxy power spectrum than with the Cosmic Microwave Background. However, the inclusion of multiple overlapping tracers, redshift bins, and more non-linear scales means that generating the necessary ensemble of simulations for model-fitting presents a computational burden. In this work, we combine full-shape fitting of galaxy power spectra, analytical covariance matrix estimates, and the MOPED compression for the first time to constrain the cosmological parameters directly from a state-of-the-art set of galaxy clustering measurements. We find it takes less than a day to compute the analytical covariance and compression matrices needed for this analysis while it takes several months to calculate the simulated ones. Additionally, the MOPED compression reduces the bias in the covariance matrix and speeds up the likelihood analysis. In combination, we find that even without a priori knowledge of the best-fit cosmological or galaxy bias parameters, the analytical covariance matrix with the MOPED compression still gives cosmological constraints consistent, to within $0.2\sigma$, with the ones obtained using the simulated covariance matrices. The pipeline we have developed here can hence significantly speed up the analysis for future surveys such as DESI and Euclid.Comment: 11 pages, 4 figures, and 1 table. To be submitted to MNRAS. Comments are welcom