deletions | additions       diff --git a/sectionMethdology_To.tex b/sectionMethdology_To.tex  index adb281a..d68b93e 100644  --- a/sectionMethdology_To.tex  +++ b/sectionMethdology_To.tex 
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Regardless of this initial visual inspection, the true nature of these filaments, and their association with a spiral feature, can only be established by looking at radial velocity data. The filament must have similar line-of-sight velocities along its length to ensure its contiguity. Moreover, the measured radial velocities should be very close to those predicted by the Milky Way's rotation curve for arms at a known distance. To investigate the velocity structure of these fifteen filaments, we employ radial velocity data from four separate radio surveys: HOPS \citep{Purcell_2012,Walsh_2011}, MALT90 \citep{Foster_2011,Jackson_2013}, BGPS spectral line follow-up \cite{Schlingman_2011,Shirley_2013} and GRS \citep{Jackson_2006}. The HOPS, MALT90, and BGPS surveys are all geared towards probing dense regions hosting the early stages of high mass star formation. We utilize $\textrm{NH}_3$ emission from HOPS, $\mathrm{N_2H^{+}}$ from MALT90, and $\textrm{HCO}^{+}$ from BGPS. All three of these thermal emission lines trace dense molecular gas ($\approx10^{4}\textrm{ cm}^{-3}$) and are often found in dense, cool clouds with temperatures less than 100 K \citep{Purcell_2012, Shirley_2013}. As infrared dark clouds tend to harbor cool, high density clumps of gas which fuel the formation of massive stars, all three of these data sets contain spectra for hundreds of regions within the longitude range of the potential Galactic bones.   In cases where HOPS, MALT90, and BGPS catalog data are not available along the extinction feature, we also extract spectra from GRS (high resolution $^{13}$CO (1-0) data) and MALT90 p-p-v cubes using the spectrum extracter tool in \href{http://www.glueviz.org/en/stable/index.html}{Glue}. Glue is a visualization tool that facilitates the linking of various data sets. We link spectral p-p-v cubes from the GRS survey with GLIMPSE-Spitzer mid-infrared images and extract velocities along different regions of the extinction feature; a demonstration of the procedure used to extract velocities in Glue is shown in the appendix. In order to ensure that that GRS velocities are consistent across the filament, we also use the slice extraction tool in Glue to obtain velocity as a function of position along a path that traces the entire extinction feature.The results of the slice extraction along the path of one of our strongest  bone candidates is shown in figure \ref{fig:filament5_slice}. As CO traces lower density gas ($\approx10^2 \textrm{ cm}^{-3}$) and $\mathrm{N_2H+}$, $\textrm{HCO}^+$, and $\textrm{NH}_3$ trace high density gas ($\approx10^4 \textrm{ cm}^{-3}$), the dense gas sources provide much stronger evidence for the velocity of cold, dense, filamentary IRDCs. However, where dense gas sources are not available, the complete and unbiased high resolution GRS survey, although less desirable, allows us to roughly gauge the velocity along entire lengths of filaments. In filaments composed entirely of GRS spectra, we also take HOPS spectra over the entire filament using Glue and confirm that this HOPS-determined velocity agreed with GRS-determined average velocity to within 5 km/s. By overlaying the HOPS, MALT90, BGPS, and GRS determined velocities on a p-v diagram of CO emission, we determine whether these filaments are contiguous in velocity structure or simply a chance projection of mid-infrared extinction features along our line-of-sight. For this study, we use the whole-galaxy \citet{Dame_2001} CO survey to locate each of the arms in p-p-v space and determine whether these filaments are consistent with global-log fits to CO for various spiral arms. Of the approximately fifteen candidates identified visually, ten of these candidates are within 10 km/s of the Scutum-Centaurus and Norma-Cygnus arms. The central coordinates for these ten filaments, along with their average lengths, LSR velocities, and distances, are listed in figure \ref{fig:candidates}. We plot these ten candidates in p-p-v space, as shown in figure \ref{fig:skeleton}. In addition to showing our Bone candidates, we show several different predictions of the positions of two spiral arms toward the inner Galaxy in longitude-velocity space, from \citet{Dame_2011}, \citet{Sanna_2014}, \citet{Shane_1972}, and \citet{Vallee_2008}. For reference, we note that the new BeSSeL (maser) results from \citet{Sato_2014} in the first quadrant favor the oldest, HI-based \citet{Shane_1972}, fits for the Scutum arm.