High Returns and Low Volatility: The Case for Mid-Cap Stocks

This study examines excess risk-adjusted returns generated by mid-cap firms with an average market equity between $2.4 billion and$5.5 billion in 2017. Researchers have heavily studied the small-firm effect since its identification in the early 1980s, leading investors to overweight small-cap securities. Additional investments in the small-cap segment caused the small-cap anomaly to weaken. This study finds that excess returns of small-cap firms compared to mid-cap firms are not statistically significant in the periods 1946 – 2017 and 1982 -2017. However, mid-cap firms generate significantly higher 3-year average returns relative to small and large-cap firms after the initial identification of the small-cap anomaly (1982 – 2017). Further, mid-cap securities generate a higher risk-adjusted return after the small-cap anomaly was identified. This study hypothesizes the mid-cap anomaly results from greater growth potential for mid-caps relative to large-caps while still being large enough to weather economic storms. This study also hypothesizes that non-size related factors have the largest impact on the mid-cap segment. The results support the existence of a mid-cap anomaly; however, the results suggest the anomaly is not a result of the growth potential of firms within the segment. Additionally, the results suggest non-size related factors such as book-to-market and operating profitability have the smallest impact on mid-cap securities. Therefore, this study concludes excess returns generated by mid-cap securities represent a true anomaly that is not dependent upon non-size related factors

Elasticity of Krull Domains with Infinite Divisor Class Group

The elasticity of a Krull domain R is equivalent to the elasticity of the block monoid B(G,S), where G is the divisor class group of R and S is the set of elements of G containing a height-one prime ideal of R. Therefore the elasticity of R can by studied using the divisor class group. In this dissertation, we will study infinite divisor class groups to determine the elasticity of the associated Krull domain. The results will focus on the divisor class groups Z, Z(p infinity), Q, and general infinite groups. For the groups Z and Z(p infinity), it has been determined which distributions of the height-one prime ideals will make R a half-factorial domain (HFD). For the group Q, certain distributions of height-one prime ideals are proven to make R an HFD. Finally, the last chapter studies general infinite groups and groups involving direct sums with Z. If certain conditions are met, then the elasticity of these divisor class groups is the same as the elasticity of simpler divisor class groups

Arab Conquests and Early Islamic Historiography: The Futuh al-Buldan of al-Baladhuri

Of the available sources for Islamic history between the seventh and eighth centuries CE, few are of greater importance than al-Baladhuri's Kitab Futuh al-buldan (The Book of the Conquest of Lands). Written in Arabic by a ninth-century Muslim scholar working at the court of the 'Abbasid caliphs, the Futuh's content covers many important matters at the beginning of Islamic history. It informs its audience of the major events of the early Islamic conquests, the settlement of Muslims in the conquered territories and their experiences therein, and the origins and development of the early Islamic state. Questions over the text's construction, purpose, and reception, however, have largely been ignored in current scholarship. This is despite both the text's important historical material and its crucial early date of creation. It has become commonplace for researchers to turn to the Futuh for information on a specific location or topic, but to ignore the grander – and, in many ways, more straightforward – questions over the text's creation and limitations. This book looks to correct these gaps in knowledge by investigating the context, form, construction, content, and early reception history of al-Baladhuri's text

Investigation of Thermal Scaling Effects for a Turbine Blade Leading Edge and Pressure Side Model

Recent experiments have attempted to quantify the overall cooling effectiveness at elevated temperature conditions. The Film Cooling Rig (FCR) at the Air Force Institute of Technology has been modified to better match the configuration of a similar large scale, low temperature rig at the Air Force Research Laboratory. This has enabled comparison and trend identification of how various properties scale from the low to high temperature condition. Various internal cooling and hole geometry configurations were investigated over a range of temperatures while utilizing the thermal scaling capability of Inconel 718. Film cooling trends and measures of overall effectiveness were matched, indicating the ability to scale among the temperature ranges tested: 350 K, 450 K, 500 K, and 550 K. Effects of blowing ratio, density ratio, and Reynolds number on overall effectiveness were investigated, as well as the ability of scaling effectiveness measurements between temperature regimes. It was found that an increase in Reynolds number caused a decrease in overall effectiveness. When matching flow parameters, this investigation found direct overall effectiveness scaling to be plausible. Additionally, overall effectiveness of about 0.5-0.6 during cases of no coolant flow were experienced due to conductive cooling to the environment. The highly conductive material also created significant heating of the coolant, drastically decreasing density ratio at the area of interest during testing, which plays an important role in assessing cooling performance

Measuring the spin of black holes in binary systems using gravitational waves

Compact binary coalescences are the most promising sources of gravitational waves (GWs) for ground based detectors. Binary systems containing one or two spinning black holes are particularly interesting due to spin-orbit (and eventual spin-spin) interactions, and the opportunity of measuring spins directly through GW observations. In this letter we analyze simulated signals emitted by spinning binaries with several values of masses, spins, orientation, and signal-to-noise ratio. We find that spin magnitudes and tilt angles can be estimated to accuracy of a few percent for neutron star--black hole systems and $\sim$ 5-30% for black hole binaries. In contrast, the difference in the azimuth angles of the spins, which may be used to check if spins are locked into resonant configurations, cannot be constrained. We observe that the best performances are obtained when the line of sight is perpendicular to the system's total angular momentum, and that a sudden change of behavior occurs when a system is observed from angles such that the plane of the orbit can be seen both from above and below during the time the signal is in band. This study suggests that the measurement of black hole spin by means of GWs can be as precise as what can be obtained from X-ray binaries.Comment: 4 figures, Version accepted for publication on PR

Self-Revision and the Arabic Historical Tradition: Identifying Textual Reuse and Reorganization in the Works of al-Baladhuri

While there is growing historiographical analysis of the reuse of circulating narrative materials in medieval books from various textual traditions, there have been fewer studies of the late antique and early medieval periods that have considered the process of authorial self-revision. This is especially the case with early Arabic/Islamicate texts. This study is a discussion of the historical material that is reused in the two surviving Arabic works of the Muslim author al-Balādhurī (d. ca. 892 CE/279 AH), material which appears in his Kitāb Futūḥ al-buldān (The Book of the Conquest of Lands) and that was apparently reused in his Ansāb al-Ashrāf (The Lineage of Nobles). In discussing how al-Balādhurī recycled this information and emplotted it in verbatim and near-verbatim forms, it shows how shifting the location of these shared traditions demonstrates the different goals of his two books and also showcases his work as an author: in the former, he places an emphasis on the creation of early Islamic institutions; in the later, he eulogizes the character and qualities of Islam’s earliest leaders. Additionally, all of the reused material discussed here was identified through computer meditated analysis, so this study also highlights how the tools of the digital and computational humanities demonstrate immense promise in enhancing and expediting the research of scholars across the medieval globe

A Survey of Analogs to Weak MgII Absorbers in the Present

We present the results of a survey of the analogs of weak MgII absorbers (rest frame equivalent width W(2796) < 0.3 A) at 0 < z < 0.3. Our sample consisted of 25 HST/STIS echelle quasar spectra (R = 45,000) which covered SiII 1260 and CII 1335 over this redshift range. Using those similar transitions as tracers of MgII facilitates a much larger survey, covering a redshift pathlength of g(z) = 5.3 for an equivalent width limit of MgII corresponding to W(2796) > 0.02 A, with 30% completeness for the weakest lines. We find the number of weak MgII absorber analogs with 0.02 < W(2796) < 0.3 to be dN/dz = 1.00 +/- 0.20 for 0 < z < 0.3. This value is consistent with cosmological evolution of the population. We consider the expected effect on observability of weak MgII absorbers of the decreasing intensity of the extragalactic background radiation eld from z~1 to z~0. Assuming that all the objects that produce absorption at z~1 are stable on a cosmological timescale, and that no new objects are created, we would expect dN/dz of 2-3 at z~0. About 30-50% of this z~0 population would be decendants of the parsec-scale structures that produce single-cloud, weak MgII absorbers at z~1. The other 50-70% would be lower density, kiloparsec-scale structures that produce CIV absorption, but not detectable low ionization absorption, at z~1. We conclude that at least one, and perhaps some fraction of both, of these populations has evolved away since z~1, in order to match the z~0 dN/dz measured in our survey. This would follow naturally for a population of transient structures whose generation is related to star-forming processes, whose rate has decreased since z~1.Comment: 45 pages, 12 figures, 7 tables ApJ accepte

An information-theoretic approach to the gravitational-wave burst detection problem

The observational era of gravitational-wave astronomy began in the Fall of 2015 with the detection of GW150914. One potential type of detectable gravitational wave is short-duration gravitational-wave bursts, whose waveforms can be difficult to predict. We present the framework for a new detection algorithm for such burst events -- \textit{oLIB} -- that can be used in low-latency to identify gravitational-wave transients independently of other search algorithms. This algorithm consists of 1) an excess-power event generator based on the Q-transform -- \textit{Omicron} --, 2) coincidence of these events across a detector network, and 3) an analysis of the coincident events using a Markov chain Monte Carlo Bayesian evidence calculator -- \textit{LALInferenceBurst}. These steps compress the full data streams into a set of Bayes factors for each event; through this process, we use elements from information theory to minimize the amount of information regarding the signal-versus-noise hypothesis that is lost. We optimally extract this information using a likelihood-ratio test to estimate a detection significance for each event. Using representative archival LIGO data, we show that the algorithm can detect gravitational-wave burst events of astrophysical strength in realistic instrumental noise across different burst waveform morphologies. We also demonstrate that the combination of Bayes factors by means of a likelihood-ratio test can improve the detection efficiency of a gravitational-wave burst search. Finally, we show that oLIB's performance is robust against the choice of gravitational-wave populations used to model the likelihood-ratio test likelihoods