Nonparametric Inference for Multivariate Data: The R Package npmv

We introduce the R package npmv that performs nonparametric inference for the comparison of multivariate data samples and provides the results in easy-to-understand, but statistically correct, language. Unlike in classical multivariate analysis of variance, multivariate normality is not required for the data. In fact, the different response variables may even be measured on different scales (binary, ordinal, quantitative). p values are calculated for overall tests (permutation tests and F approximations), and, using multiple testing algorithms which control the familywise error rate, significant subsets of response variables and factor levels are identified. The package may be used for low- or highdimensional data with small or with large sample sizes and many or few factor levels

Pavement Management in Kentucky

The principal objective of this paper is to summarize current pavement management activities in Kentucky. Early pavement management activities generally were decentralized (involving a number of transportation functions such as planning, design, construction, maintenance, and research) and involved long-term monitoring for skid resistance and ride quality (roughness). Current pavement management activities may be categorized by evaluation, project selection, and development of recommendations for pavement rehabilitation strategies. Pavement evaluation activities at the statewide system level typically involve assessments of ride quality (ridesbility index) and estimated pavement serviceability, skid resistance, visual condition ratings, and the accumulation of traffic volumes and pavement fatigue. Funding allocations to highway districts involves the application of limiting criteria to system level data obtained during the evaluation phase. Factors considered include rideability index (estimated from roughness measurements), skid resistance, visual condition ratings, accumulation of traffic volumes and fatigue, and engineering judgment. Recommendations for rehabilitation strategies also may be based on structural evaluations using deflection measurements. Typical rehabilitation strategies are discussed. Procedures and criteria for the allocation and distribution of funding to the highway districts are presented

A Comprehensive Investigation of Metals in the Circumgalactic Medium of Nearby Dwarf Galaxies

Dwarf galaxies are found to have lost most of their metals via feedback processes; however, there still lacks consistent assessment on the retention rate of metals in their circumgalactic medium (CGM). Here we investigate the metal content in the CGM of 45 isolated dwarf galaxies with $M_*=10^{6.5-9.5}~M_\odot$ ($M_{\rm 200m}=10^{10.0-11.5}~M_\odot$) using {\it HST}/COS. While H I (Ly$\alpha$) is ubiquitously detected ($89\%$) within the CGM, we find low detection rates ($\approx5\%-22\%$) in C II, C IV, Si II, Si III, and Si IV, largely consistent with literature values. Assuming these ions form in the cool ($T\approx10^4$ K) CGM with photoionization equilibrium, the observed H I and metal column density profiles can be best explained by an empirical model with low gas density and high volume filling factor. For a typical galaxy with $M_{\rm 200m}=10^{10.9}~M_\odot$ (median of the sample), our model predicts a cool gas mass of $M_{\rm CGM,cool}\sim10^{8.4}~M_\odot$, corresponding to $\sim2\%$ of the galaxy's baryonic budget. Assuming a metallicity of $0.3Z_\odot$, we estimate that the dwarf galaxy's cool CGM likely harbors $\sim10\%$ of the metals ever produced, with the rest either in more ionized states in the CGM or transported to the intergalactic medium. We further examine the EAGLE simulation and show that H I and low ions may arise from a dense cool medium, while C IV arises from a diffuse warmer medium. Our work provides the community with a uniform dataset on dwarf galaxies' CGM that combines our recent observations, additional archival data and literature compilation, which can be used to test various theoretical models of dwarf galaxies.Comment: Finalized version. Accepted for publication in Ap

Tentative detection of the circumgalactic medium of the isolated low-mass dwarf galaxy WLM

We report a tentative detection of the circumgalactic medium (CGM) of Wolf–Lundmark–Melotte (WLM), an isolated, low-mass (logM*/M⊙ ≈ 7.6), dwarf irregular galaxy in the Local Group (LG). We analyse an HST/COS archival spectrum of a quasar sightline (PHL2525), which is 45 kpc (0.5 virial radius) from WLM and close to the Magellanic Stream (MS). Along this sightline, two ion absorbers are detected in Si II, Si III, Si IV, C II, and C IV at velocities of ∼−220 km s⁻¹ (Component v-220) and ∼−150 km s⁻¹ (Component v-150). To identify their origins, we study the position–velocity alignment of the components with WLM and the nearby MS. Near the magellanic longitude of PHL2525, the MS-related neutral and ionized gas moves at ≲−190 km s⁻¹, suggesting an MS origin for Component v-220, but not for Component v-150. Because PHL2525 passes near WLM and Component v-150 is close to WLM’s systemic velocity (∼−132 km s⁻¹), it is likely that Component v-150 arises from the galaxy’s CGM. This results in a total Si mass in WLM’s CGM of M^(CGM)_(Si)∼(0.2−1.0)×10⁵ M⊙ using assumption from other COS dwarf studies. Comparing M^(CGM)_(Si) to the total Si mass synthesized in WLM over its lifetime (∼1.3 × 10⁵ M⊙), we find ∼3 per cent is locked in stars, ∼6 per cent in the ISM, ∼15–77 per cent in the CGM, and the rest (∼14–76 per cent) is likely lost beyond the virial radius. Our finding resonates with other COS dwarf galaxy studies and theoretical predictions that low-mass galaxies can easily lose metals into their CGM due to stellar feedback and shallow gravitational potential

Gas Accretion in Star-Forming Galaxies

Cold-mode gas accretion onto galaxies is a direct prediction of LCDM simulations and provides galaxies with fuel that allows them to continue to form stars over the lifetime of the Universe. Given its dramatic influence on a galaxy's gas reservoir, gas accretion has to be largely responsible for how galaxies form and evolve. Therefore, given the importance of gas accretion, it is necessary to observe and quantify how these gas flows affect galaxy evolution. However, observational data have yet to conclusively show that gas accretion ubiquitously occurs at any epoch. Directly detecting gas accretion is a challenging endeavor and we now have obtained a significant amount of observational evidence to support it. This chapter reviews the current observational evidence of gas accretion onto star-forming galaxies.Comment: Invited review to appear in Gas Accretion onto Galaxies, Astrophysics and Space Science Library, eds. A. J. Fox & R. Dav\'e, to be published by Springer. This chapter includes 22 pages with 7 Figure