Teaching Notes for CHAPTER 7: Leading Healing in a Broken Unit

Teaching Notes for Leading Healing in a Broken Unit, by Edward H. Powley and Scott N. Taylor. Source material for this case study comes from the following: the first-hand experiences of an officer embedded within the ground combat element of a Marine Air Ground Task Force; reports on the use of improvised explosive devices (IEDs) in Iraq and Afghanistan; and first-hand knowledge of military officers recently returned from combat operations. Specific names, dates, and locations have been changed and descriptive background information added. The announcement of increased deployments meant additional preparations for many military units that anticipated deployment to the U.S. Central Command (CENTCOM) area of operations. This case is about one ground combat element for a Marine Air Ground Task Force deployed into the CENTCOM area of operations. Excitement for the mission remained high, but extended deadlines well beyond the return date caused Marines and sailors to become wary. On top of their fatigue, a suicide bomber detonated himself at an entry control point, significantly affecting the morale and welfare of the unit. The blast killed several individuals and severely wounded nearly a dozen others. One of those killed in the blast was the well-known and well-respected senior enlisted leader of the ground combat element. In life, as in death, his presence affected the morale and productivity of the entire unit. Would his loss paralyze the unit? How would the unit rebound, pick up the pieces, and return with honor? How would the officers lead the unit toward healing in the remaining weeks of the deployment? These questions were in the forefront of the officers’ minds as they struggled to keep the unit moving forward

Evolution of the stellar mass function and infrared luminosity function of galaxies since z = 1.2

© 2019. The American Astronomical Society. All rights reserved. We measured evolution of the K-band luminosity function and stellar mass function (SMF) for red and blue galaxies at z 0.4 luminosity and mass function measurements. Using an evolving relation for K-band mass-to-light ratios as a function of (B-V) color, we found a slowly decreasing rate of growth in red galaxy stellar mass density of ×2.3 from z ∼ 1.1 to z ∼ 0.3, indicating a slowly decreasing rate of migration from the blue cloud to the red sequence. Unlike some studies of the SMF, we find that massive red galaxies grow by a factor of ×1.7 from z ∼ 1.1 to z ∼ 0.3, with the rate of growth due to mergers decreasing with time. These results are comparable with measurements of merger rates and clustering, and they are also consistent with the red galaxy stellar mass growth implied by comparing K-band luminosity evolution with the fading of passive stellar population models

Optical Spectroscopy Of X-Ray Sources In The Extended Chandra Deep Field South

We present the first results of our optical spectroscopy program aimed to provide redshifts and identifications for the X-ray sources in the Extended Chandra Deep Field South. A total of 339 sources were targeted using the IMACS spectrograph at the Magellan telescopes and the VIMOS spectrograph at the VLT. We measured redshifts for 186 X-ray sources, including archival data and a literature search. We find that the active galactic nucleus (AGN) host galaxies have on average redder rest-frame optical colors than nonactive galaxies, and that they live mostly in the "green valley." The dependence of the fraction of AGNs that are obscured on both luminosity and redshift is confirmed at high significance and the observed AGN spatial density is compared with the expectations from existing luminosity functions. These AGNs show a significant difference in the mid-IR to X-ray flux ratio for obscured and unobscured AGNs, which can be explained by the effects of dust self-absorption on the former. This difference is larger for lower luminosity sources, which is consistent with the dust opening angle depending on AGN luminosity.National Aeronautics and Space Administration PF8-90055, NAS8-03060NSF AST0407295Spitzer JPL RSA1288440Natural Science and Engineering Research Council of Canada (NSERC)National Academy of SciencesNASA/INTEGRAL NNG05GM79GAstronom

Analyses of space environment effects on active fiber optic links orbited aboard the LDEF

The results of the 'Preliminary Analysis of WL Experiment no. 701, Space Environment Effects on Operating Fiber Optic Systems,' is correlated with space simulated post retrieval terrestrial studies performed on the M0004 experiment. Temperature cycling measurements were performed on the active optical data links for the purpose of assessing link signal to noise ratio and bit error rate performance some 69 months following the experiment deployment in low Earth orbit. The early results indicate a high correlation between pre-orbit, orbit, and post-orbit functionality of the first known and longest space demonstration of operating fiber optic systems

Strong lensing selection effects

Context. Strong lenses are a biased subset of the general population of galaxies. Aims. The goal of this work is to quantify how lens galaxies and lensed sources differ from their parent distribution, namely the strong lensing bias. Methods. We first studied how the strong lensing cross-section varies as a function of lens and source properties. Then, we simulated strong lensing surveys with data similar to that expected for Euclid and measured the strong lensing bias in different scenarios. We focused particularly on two quantities: the stellar population synthesis mismatch parameter, $\alpha_{sps}$, defined as the ratio between the true stellar mass of a galaxy and the stellar mass obtained from photometry, and the central dark matter mass at fixed stellar mass and size. Results. Strong lens galaxies are biased towards larger stellar masses, smaller half-mass radii and larger dark matter masses. The amplitude of the bias depends on the intrinsic scatter in the mass-related parameters of the galaxy population and on the completeness in Einstein radius of the lens sample. For values of the scatter that are consistent with observed scaling relations and a minimum detectable Einstein radius of $0.5''$, the strong lensing bias in $\alpha_{sps}$ is $10\%$, while that in the central dark matter mass is $5\%$. The bias has little dependence on the properties of the source population: samples of galaxy-galaxy lenses and galaxy-quasar lenses that probe the same Einstein radius distribution are biased in a very similar way. Conclusions. Given current uncertainties, strong lensing observations can be used directly to improve our current knowledge of the inner structure of galaxies, without the need to correct for selection effects. Time-delay measurements of $H_0$ from lensed quasars can take advantage of prior information obtained from galaxy-galaxy lenses with similar Einstein radii.Comment: Published on Astronomy & Astrophysics. A two-minute summary video of this paper is available at https://youtu.be/UmS9jRHTmZ

Spontaneous synchronization of coupled oscillator systems with frequency adaptation

We study the synchronization of Kuramoto oscillators with all-to-all coupling in the presence of slow, noisy frequency adaptation. In this paper we develop a new model for oscillators which adapt both their phases and frequencies. It is found that this model naturally reproduces some observed phenomena that are not qualitatively produced by the standard Kuramoto model, such as long waiting times before the synchronization of clapping audiences. By assuming a self-consistent steady state solution, we find three stability regimes for the coupling constant k, separated by critical points k1 and k2: (i) for k<k1, only the stable incoherent state exists; (ii) for k>k2, the incoherent state becomes unstable and only the synchronized state exists; (iii) for k1<k<k2, both the incoherent and synchronized states are stable. In the bistable regime spontaneous transitions between the incoherent and synchronized states are observed for finite ensembles. These transitions are well described as a stochastic process on the order parameter r undergoing fluctuations due to the system's finite size, leading to the following conclusions: (a) in the bistable regime, the average waiting time of an incoherent-to-coherent transition can be predicted by using Kramer's escape time formula and grows exponentially with the number of oscillators; (b) when the incoherent state is unstable (k>k2), the average waiting time grows logarithmically with the number of oscillators.Comment: 8 page Tex file, 6 figure