Forecasting Attrition by AFSC for the United States Air Force

Retention and personnel management is a challenge for every organization, particularly the military due to its hierarchical structure and barriers to entry. Talent must be developed and retained to become leaders, beginning at the lowest level in the Air Force. The Air Force faces a retention problem unlike most organizations that requires a unique perspective and tailored solution to each Air Force Specialty Code (AFSC). There exists previous efforts to predict attrition rates in the Air Force based on economic factors. This study expands upon the economic factors and tailors the predictor variables of attrition based on the AFSC. The current research hypothesizes that AFSC attrition has a relationship with comparable civilian jobs and their employment rates. The methodology identifies the key factors influencing attrition, creates forecasts for the variables, and reintroduces the forecasts of the variables into the original regression to provide forecasts of expected attrition along with confidence regions. This study finds that seven of the eight AFSCs show a relationship with comparable employment in the civilian sector. More insights show that AFSCs have different predictor variables and should be modelled separately to capture the trends for each specific AFSC. These insights to leadership will aid in decisions for AFSC retention bonuses as well as informing recruitment services of critically manned career fields

The Green Bank Telescope H II Region Discovery Survey: IV. Helium and Carbon Recombination Lines

The Green Bank Telescope H II Region Discovery Survey (GBT HRDS) found hundreds of previously unknown Galactic regions of massive star formation by detecting hydrogen radio recombination line (RRL) emission from candidate H II region targets. Since the HRDS nebulae lie at large distances from the Sun, they are located in previously unprobed zones of the Galactic disk. Here we derive the properties of helium and carbon RRL emission from HRDS nebulae. Our target sample is the subset of the HRDS that has visible helium or carbon RRLs. This criterion gives a total of 84 velocity components (14% of the HRDS) with helium emission and 52 (9%) with carbon emission. For our highest quality sources, the average ionic He-4+/H+ abundance ratio by number, , is 0.068 +/- 0.023 (1-sigma). This is the same ratio as that measured for the sample of previously known Galactic H II regions. Nebulae without detected helium emission give robust y+ upper limits. There are 5 RRL emission components with y+ less than 0.04 and another 12 with upper limits below this value. These H II regions must have either a very low He-4 abundance or contain a significant amount of neutral helium. The HRDS has 20 nebulae with carbon RRL emission but no helium emission at its sensitivity level. There is no correlation between the carbon RRL parameters and the 8 microns mid-infrared morphology of these nebulae.Comment: Accepted to ApJ. The survey website can be found here: http://go.nrao.edu/hrd

HII Region Ionization of the Interstellar Medium: A Case Study of NGC 7538

Using data from the Green Bank Telescope, we analyze the radio continuum (free-free) and radio recombination line (RRL) emission of the compact HII region NGC 7538 (Sharpless 158). We detect extended radio continuum and hydrogen RRL emission beyond the photodissociation region (PDR) toward the north and east, but a sharp decrease in emission toward the south and west. This indicates that a non-uniform PDR morphology is affecting the amount of radiation "leaking" through the PDR. The strongest carbon RRL emission is found in the western PDR that appears to be dense. We compute a leaking fraction $f_R = 15 \pm 5$ % of the radio continuum emission measured in the plane of the sky which represents a lower limit when accounting for the three-dimensional geometry of the region. We detect an average $^4\textrm{He}^+/\textrm{H}^+$ abundance ratio by number of $0.088 \pm 0.003$ inside the HII region and a decrease in this ratio with increasing distance from the region beyond the PDR. Using Herschel Space Observatory data, we show that small dust temperature enhancements to the north and east of NGC 7538 coincide with extended radio emission, but that the dust temperature enhancements are mostly contained within a second PDR to the east. Unlike the giant HII region W43, the radiation leaking from NGC 7538 seems to only affect the local ambient medium. This suggests that giant HII regions may have a large effect in maintaining the ionization of the interstellar medium.Comment: Accepted for publication in ApJ (15 pages, 10 figures, 2 tables

Diffuse Ionized Gas in the Milky Way Disk

We analyze the diffuse ionized gas (DIG) in the first Galactic quadrant from l=18deg to 40deg using radio recombination line (RRL) data from the Green Bank Telescope. These data allow us to distinguish DIG emission from HII region emission and thus study the diffuse gas essentially unaffected by confusion from discrete sources. We find that the DIG has two dominant velocity components, one centered around 100km/s associated with the luminous HII region W43, and the other centered around 45km/s not associated with any large HII region. Our analysis suggests that the two velocity components near W43 may be caused by non-circular streaming motions originating near the end of the Galactic bar. At lower Galactic longitudes, the two velocities may instead arise from gas at two distinct distances from the Sun, with the most likely distances being ~6kpc for the 100km/s component and ~12kpc for the 45km/s component. We show that the intensity of diffuse Spitzer GLIMPSE 8.0um emission caused by excitation of polyaromatic hydrocarbons (PAHs) is correlated with both the locations of discrete HII regions and the intensity of the RRL emission from the DIG. This implies that the soft ultra-violet photons responsible for creating the infrared emission have a similar origin as the harder ultra-violet photons required for the RRL emission. The 8.0um emission increases with RRL intensity but flattens out for directions with the most intense RRL emission, suggesting that PAHs are partially destroyed by the energetic radiation field at these locations.Comment: Accepted for publication in ApJ (16 pages, 11 figures, 2 tables

Diffuse Ionized Gas in the Milky Way Disk

We analyze the diffuse ionized gas (DIG) in the first Galactic quadrant from l=18deg to 40deg using radio recombination line (RRL) data from the Green Bank Telescope. These data allow us to distinguish DIG emission from HII region emission and thus study the diffuse gas essentially unaffected by confusion from discrete sources. We find that the DIG has two dominant velocity components, one centered around 100km/s associated with the luminous HII region W43, and the other centered around 45km/s not associated with any large HII region. Our analysis suggests that the two velocity components near W43 may be caused by non-circular streaming motions originating near the end of the Galactic bar. At lower Galactic longitudes, the two velocities may instead arise from gas at two distinct distances from the Sun, with the most likely distances being ~6kpc for the 100km/s component and ~12kpc for the 45km/s component. We show that the intensity of diffuse Spitzer GLIMPSE 8.0um emission caused by excitation of polyaromatic hydrocarbons (PAHs) is correlated with both the locations of discrete HII regions and the intensity of the RRL emission from the DIG. This implies that the soft ultra-violet photons responsible for creating the infrared emission have a similar origin as the harder ultra-violet photons required for the RRL emission. The 8.0um emission increases with RRL intensity but flattens out for directions with the most intense RRL emission, suggesting that PAHs are partially destroyed by the energetic radiation field at these locations.Comment: Accepted for publication in ApJ (16 pages, 11 figures, 2 tables

Challenges in identifying cancer genes by analysis of exome sequencing data.

Massively parallel sequencing has permitted an unprecedented examination of the cancer exome, leading to predictions that all genes important to cancer will soon be identified by genetic analysis of tumours. To examine this potential, here we evaluate the ability of state-of-the-art sequence analysis methods to specifically recover known cancer genes. While some cancer genes are identified by analysis of recurrence, spatial clustering or predicted impact of somatic mutations, many remain undetected due to lack of power to discriminate driver mutations from the background mutational load (13-60% recall of cancer genes impacted by somatic single-nucleotide variants, depending on the method). Cancer genes not detected by mutation recurrence also tend to be missed by all types of exome analysis. Nonetheless, these genes are implicated by other experiments such as functional genetic screens and expression profiling. These challenges are only partially addressed by increasing sample size and will likely hold even as greater numbers of tumours are analysed