An Examination of the College Major Decisions of Students at the University of Mississippi

Factors such as socio-economic status affect students\u27 level of educational aspiration. Furthermore, major (and thus career choice) may be influenced by race or gender. This study demonstrates the effects of academic aptitude, race, gender, first generation status, and importance of expected future earnings on undergraduate students\u27 college major decision. More specifically, this study examines if these factors lead to an increase or decrease in the probability of students choosing a major in a specific field. The likelihood of choosing a major in a specific field is relative a baseline category, which can be changed

Tornado Trouble: How Can Current Tornado Warnings be Improved?

There are many unnecessary deaths from tornadoes every year (NOAA.org, 2013). Although there have been great advancements in tornado warning systems (Coleman, Knupp, Spann, Elliot, & Peters, 2010), more changes to systems could be made to motivate people to take action in preparation for tornadoes (Brotzge & Donner, 2013). Protection motivation theory outlines the process by which we assess threats and decide whether or not preventative actions are worth performing. If the threat is perceived as severe enough and the preventative actions are seen as capable of mitigating the threat, the individual is motivated to act (Rogers, 2000). One means by which to enhance the efficacy of weather warnings is through the use of visual imagery. Research has shown that pictures are more easily remembered than words (e.g., Jenkins, Neale & Deno, 1967), and that the addition of picture descriptions or “pictorials” to public safety warnings increases the comprehension and perceptions of risks (Wogalter & Laughery 1997; Severson & Henriques, 2009 respectively). However, the effect of pictures varies depending on many factors including how closely the pictures are perceptually linked to the text and how the picture relates to the target audience (Houts, Doak, Doak, & Loscalzo, 2006). In the current study, we examined the influence of visual imagery in the context of tornado warnings. Specifically, we examined the effects of different tornado warnings on perceptions of susceptibility, response efficacy, and self-efficacy. The warnings varied by whether or not they contained pictures of damage, pictures of preparations, or no pictures. The pictures also varied by tornado category (F2 or F4). F4 warnings were expected to elicit greater susceptibility than F2 warnings. Warnings with pictures of damage were expected to elicit higher susceptibility in an interactive effect in the context of F4 warnings than those with preparation or no pictures. Warnings with preparation pictures were expected to elicit greater levels of efficacy than those with damage or no pictures. Warnings with either type of picture were expected to elicit higher levels of comprehension. The results revealed that participants who viewed the F4 warnings perceived themselves to be more at risk than those who viewed the F2 warnings. There was an effect of both damage and preparation pictures on response efficacy of actions recommended in the event of a tornado, such that those who viewed warnings with either type of picture rated the recommended actions as more efficacious that those who simply saw a text warning. Also, in this study a trend was observed such that participants who viewed more severe tornado warnings (i.e., F4) rated themselves as more efficacious (self-efficacy) in the event of a tornado than those who viewed less severe tornado warnings (i.e., F2). Also of importance, those who viewed the F4 warnings had overall lower comprehension of damage or susceptibility related information when compared to those who viewed F2 warnings. Implications of results and future directions are discussed

Unifying Amplitude and Phase Analysis: A Compositional Data Approach to Functional Multivariate Mixed-Effects Modeling of Mandarin Chinese

Mandarin Chinese is characterized by being a tonal language; the pitch (or $F_0$) of its utterances carries considerable linguistic information. However, speech samples from different individuals are subject to changes in amplitude and phase which must be accounted for in any analysis which attempts to provide a linguistically meaningful description of the language. A joint model for amplitude, phase and duration is presented which combines elements from Functional Data Analysis, Compositional Data Analysis and Linear Mixed Effects Models. By decomposing functions via a functional principal component analysis, and connecting registration functions to compositional data analysis, a joint multivariate mixed effect model can be formulated which gives insights into the relationship between the different modes of variation as well as their dependence on linguistic and non-linguistic covariates. The model is applied to the COSPRO-1 data set, a comprehensive database of spoken Taiwanese Mandarin, containing approximately 50 thousand phonetically diverse sample $F_0$ contours (syllables), and reveals that phonetic information is jointly carried by both amplitude and phase variation.Comment: 49 pages, 13 figures, small changes to discussio

Reduced heterozygosity impairs sperm quality in endangered mammals

Inbreeding causes increases in homozygosity and is commonly associated with reductions in fertility and embryogenesis. Although the mechanisms underlying such effects are unknown, recent work has suggested that inbred males may suffer impaired ejaculate quality, thus providing a functional explanation for reductions in reproductive function in inbred populations. However, the relationship between inbreeding and sperm quality remains controversial, particularly in wild populations where the level of inbreeding is typically estimated using neutral molecular markers. Such markers are thought to reflect genome-wide levels of heterozygosity only under restricted conditions, and rarely in outbred populations. Here we employ a comparative approach that takes account of these criticisms and evaluates the evidence linking inbreeding to reductions in sperm quality in 20 mammal species. We focus on sperm abnormalities and sperm motility, which are key determinants of male fertility in many species. We show that species with reduced mean heterozygosity have impaired ejaculated quality, although subsequent analyses revealed that these effects were confined to endangered populations. Our findings therefore support the notion that inbreeding can severely impair sperm quality while concomitantly addressing criticisms surrounding the use of heterozygosity estimates to estimate the level of inbreeding

Male Genital Morphology and Its Influence on Female Mating Preferences and Paternity Success in Guppies

In internally fertilizing species male genitalia often show a higher degree of elaboration than required for simply transferring sperm to females. Among the hypotheses proposed to explain such diversity, sexual selection has received the most empirical support, with studies revealing that genital morphology can be targeted by both pre-and postcopulatory sexual selection. Until now, most studies have focused on these two episodes of selection independently. Here, we take an alternative approach by considering both components simultaneously in the livebearing fish, Poecilia reticulata. We allowed females to mate successively (and cooperatively) with two males and determined whether male genital length influenced the female's propensity to mate with a male (precopulatory selection, via female choice) and whether male genital size and shape predicted the relative paternity share of subsequent broods (postcopulatory selection, via sperm competition/cryptic female choice). We found no evidence that either episode of sexual selection targets male genital size or shape. These findings, in conjunction with our recent work exposing a role of genital morphology in mediating unsolicited (forced) matings in guppies, further supports our prior speculation that sexual conflict may be an important broker of genital evolution in this species

Nature Of Transition Circumstellar Disks. I. The Ophiuchus Molecular Cloud

We have obtained millimeter-wavelength photometry, high-resolution optical spectroscopy, and adaptive optics near-infrared imaging for a sample of 26 Spitzer-selected transition circumstellar disks. All of our targets are located in the Ophiuchus molecular cloud (d similar to 125 pc) and have spectral energy distributions (SEDs) suggesting the presence of inner opacity holes. We use these ground-based data to estimate the disk mass, multiplicity, and accretion rate for each object in our sample in order to investigate the mechanisms potentially responsible for their inner holes. We find that transition disks are a heterogeneous group of objects, with disk masses ranging from <0.6 to 40 M(JUP) and accretion rates ranging from <10(-11) to 10(-7) M(circle dot) yr(-1), but most tend to have much lower masses and accretion rates than "full disks" (i.e., disks without opacity holes). Eight of our targets have stellar companions: six of them are binaries and the other two are triple systems. In four cases, the stellar companions are close enough to suspect they are responsible for the inferred inner holes. We find that nine of our 26 targets have low disk mass (<2.5 M(JUP)) and negligible accretion (<10(-11) M(circle dot) yr(-1)), and are thus consistent with photoevaporating (or photoevaporated) disks. Four of these nine non-accreting objects have fractional disk luminosities <10(-3) and could already be in a debris disk stage. Seventeen of our transition disks are accreting. Thirteen of these accreting objects are consistent with grain growth. The remaining four accreting objects have SEDs suggesting the presence of sharp inner holes, and thus are excellent candidates for harboring giant planets.NASA 1224608, 1230782, 1230779, 1407FONDECYT 1061199Basal CATA PFB 06/09ALMA FUND 31070021ALMA-Conicyt FUND 31060010National Science Foundation AST0-808144Spitzer Space Telescope Legacy Science ProgramAstronom

The Masses of Transition Circumstellar Disks: Observational Support for Photoevaporation Models

We report deep Sub-Millimeter Array observations of 26 pre-main-sequence (PMS) stars with evolved inner disks. These observations measure the mass of the outer disk (r ~20-100 AU) across every stage of the dissipation of the inner disk (r < 10 AU) as determined by the IR spectral energy distributions (SEDs). We find that only targets with high mid-IR excesses are detected and have disk masses in the 1-5 M_Jup range, while most of our objects remain undetected to sensitivity levels of M_DISK ~0.2-1.5 M_Jup. To put these results in a more general context, we collected publicly available data to construct the optical to millimeter wavelength SEDs of over 120 additional PMS stars. We find that the near-IR and mid-IR emission remain optically thick in objects whose disk masses span 2 orders of magnitude (~0.5-50 M_Jup). Taken together, these results imply that, in general, inner disks start to dissipate only after the outer disk has been significantly depleted of mass. This provides strong support for photoevaporation being one of the dominant processes driving disk evolution.Comment: Accepted for publication by ApJL, 4 pages and 3 figure

Simulating spatial and temporal evolution of multiple wing cracks around faults in crystalline basement rocks

Fault zones are structurally highly spatially heterogeneous and hence extremely complex. Observations of fluid flow through fault zones over several scales show that this structural complexity is reflected in the hydrogeological properties of faults. Information on faults at depth is scarce, hence, it is highly valuable to understand the controls on spatial and temporal fault zone development. In this paper we increase our understanding of fault damage zone development in crystalline rocks by dynamically simulating the growth of single and multiple splay fractures produced from failure on a pre-existing fault. We present a new simulation model, MOPEDZ (Modeling Of Permeability Evolution in the Damage Zone surrounding faults), that simulates fault evolution through solution of Navier's equation with a combined Mohr-Coulomb and tensile failure criteria. Simulations suggest that location, frequency, mode of failure and orientation of splay fractures are significantly affected both by the orientation of the fault with respect to the maximum principal compressive stress and the conditions of differential stress. Model predictions compare well with published field outcrop data, confirming that this model produces realistic damage zone geometries