Seasonal facilitative and competitive trade‐offs between shrub seedlings and coastal grasses

Shrub expansion is occurring in grasslands globally and may be impacted by the balance of competition and facilitation with existing grasses. Along the mid‐Atlantic and Gulf coasts, the native shrub Morella cerifera (wax myrtle) is rapidly expanding and displacing other native coastal species. Recent research suggests that much of this expansion is due to warming winter temperatures, as temperatures below −15°C kill M. cerifera. The objective of this project was to understand the importance of species interactions with grasses on the growth and physiology of M. cerifera at the seedling life stage through both field and laboratory experiments. In the field, grasses were removed around seedlings and microclimate and shrub physiology and growth were measured. Seeds and seedlings were experimentally frozen to measure the freeze tolerance at both life stages. We found that grasses provided ~1.3°C insulation to shrubs during winter. A freezing threshold for M. cerifera seedlings was experimentally found between −6°C and −11°C, but seeds remained viable after being frozen to the coldest ecologically relevant temperatures. Seedlings competed for light with grasses during warm months and grew more where grasses were clipped, revealing a trade‐off between winter insulation and summer light competition. Morella cerifera exhibits ecosystem engineering at the seedling stage by significantly reducing summer maximum temperatures. When seedlings are very young (less than one year), grasses appear to improve germination and seedling survival. These phenomena enable rapid expansion of M. cerifera across the landscape and likely inform shrub expansion mechanisms in other systems. Although seedlings are small and relatively vulnerable, this life stage appears to have significant implications for ecosystem trajectory in grasslands undergoing shrub encroachment

Parametric inference of recombination in HIV genomes

Recombination is an important event in the evolution of HIV. It affects the global spread of the pandemic as well as evolutionary escape from host immune response and from drug therapy within single patients. Comprehensive computational methods are needed for detecting recombinant sequences in large databases, and for inferring the parental sequences. We present a hidden Markov model to annotate a query sequence as a recombinant of a given set of aligned sequences. Parametric inference is used to determine all optimal annotations for all parameters of the model. We show that the inferred annotations recover most features of established hand-curated annotations. Thus, parametric analysis of the hidden Markov model is feasible for HIV full-length genomes, and it improves the detection and annotation of recombinant forms. All computational results, reference alignments, and C++ source code are available at http://bio.math.berkeley.edu/recombination/.Comment: 20 pages, 5 figure

THE INFLUENCE OF DEPRESSIVE SYMPTOMS ON FATHERS’ BEHAVIORS AND ATTITUDES

The present study examines the impact of young, poor, unwed fathers on their family by investigating the influence of depressive symptom frequency on fathers’ relationship with their children and partners. Couples from seven American cities with populations over 200,000 were recruited and interviewed about such areas of life as romantic and parental relationships, health, and employment at the hospital within 24 hours after the birth of their child. An Item Response Theory (IRT) within-group analysis of the 1,759 African-, Caucasian-, Hispanic-, Asian-, and Native American fathers in the study yielded a 3-class clustering of depressive symptoms. Class 1 fathers had the lowest frequency of depressive symptom expression; class 2 fathers had a low frequency; and class 3 fathers had low to medium rates of depressive symptoms. Multivariate statistics revealed that depressive class membership predicted domestic violence toward fathers’ partners but not affection toward their children. The importance of the parental behavior of teaching children about life, however, varied by class, with class 2 fathers most highly endorsing this behavior. Implications of young, unwed, poor fathers' behaviors and attitudes toward their children and romantic partners will be discussed in terms of men's contributions to family life.

A time dependent relation between EUV solar flare light-curves from lines with differing formation temperatures

Extreme ultraviolet (EUV) solar flare emissions evolve in time as the emitting plasma heats and then cools. Although accurately modeling this evolution has been historically difficult, especially for empirical relationships, it is important for understanding processes at the Sun, as well as for their influence on planetary atmospheres. With a goal to improve empirical flare models, a new simple empirical expression is derived to predict how cool emissions will evolve based on the evolution of a hotter emission. This technique is initially developed by studying 12 flares in detail observed by the EUV Variability Experiment (EVE) onboard the Solar Dynamics Observatory (SDO). Then, over 1100 flares observed by EVE are analyzed to validate these relationships. The Cargill and Enthalpy Based Thermal Evolution of Loops (EBTEL) flare cooling models are used to show that this empirical relationship implies the energy radiated by a population of hotter formed ions is approximately proportional to the energy exciting a population of cooler formed ions emitting when the peak formation temperatures of the two lines are up to 72% of each other and above 2 MK. These results have practical implications for improving flare irradiance empirical modeling and for identifying key emission lines for future monitoring of flares for space weather operations; and also provide insight into the cooling processes of flare plasma.Comment: Final version accepted for publication by the Journal of Space Weather and Space Climate on 23 November 201

A Weak Gravitational Lensing Analysis of Abell 2390

We report on the detection of dark matter in the cluster Abell 2390 using the weak gravitational distortion of background galaxies. We find that the cluster light and total mass distributions are quite similar over an angular scale of \simeq 7^\prime \;(1 \Mpc). The cluster galaxy and mass distributions are centered on the cluster cD galaxy and exhibit elliptical isocontours in the central \simeq 2^\prime \; (280 \kpc). The major axis of the ellipticity is aligned with the direction defined by the cluster cD and a ``straight arc'' located $\simeq 38^{\prime\prime}$ to the northwest. We determined the radial mass-to-light profile for this cluster and found a constant value of $(320 \pm 90) h\; M_\odot/L_{\odot V}$, which is consistent with other published determinations. We also compared our weak lensing azimuthally averaged radial mass profile with a spherical mass model proposed by the CNOC group on the basis of their detailed dynamical study of the cluster. We find good agreement between the two profiles, although there are weak indications that the CNOC density profile may be falling more steeply for $\theta\geq 3^\prime$ (420\kpc).Comment: 14 pages, latex file. Postscript file and one additional figure are available at ftp://magicbean.berkeley.edu/pub/squires/a2390/massandlight.ps.g

Where Are The Dead? A Discussion of Hades-The Spirit Realm. Are The Dead Conscious? Shall We Know Each Other In Heaven?

https://digitalcommons.acu.edu/crs_books/1243/thumbnail.jp

The Formation of Low-Mass Double White Dwarfs through an Initial Phase of Stable Non-Conservative Mass Transfer

Although many double white dwarfs (DWDs) have been observed, the evolutionary channel by which they are formed from low-mass/long-period red-giant-main-sequence (RG-MS) binaries remains uncertain. The canonical explanations involve some variant of double common-envelope (CE) evolution, however it has been found that such a mechanism cannot produce the observed distribution. We present a model for the initial episode of mass transfer (MT) in RG-MS binaries, and demonstrate that their evolution into double white dwarfs need not arise through a double-CE process, as long as the initial primary's core mass (Md,c) does not exceed 0.46M$_{\odot}$. Instead, the first episode of dramatic mass loss may be stable, non-conservative MT. We find a lower bound on the fraction of transferred mass that must be lost from the system in order to provide for MT, and demonstrate the feasibility of this channel in producing observed low-mass (with M$_{d,c}$ < 0.46M$_{\odot}$) DWD systems.Comment: 2 pages, 1 figure, Conference Proceedings for the International Conference on Binaries, Mykonos, Greec

The Menace of the Movies

https://digitalcommons.acu.edu/crs_books/1323/thumbnail.jp

Critical period conditioning by orgasm during heterosexual oral sex

Data were obtained retrospectively and anonymously using a computerized survey instrument from 450 female and 489 male participants who had experienced orgasm during oral sex before age 18, as well as 352 female and 151 male participants who had not experienced an orgasm while receiving oral sex before age 18. Female participants who experienced an orgasm during oral sex prior to age 18 were significantly more likely to experience an orgasm during oral sex after age 18. For male participants, although the difference was in the hypothesized direction, it did not reach significance. Female participants who experienced an orgasm during oral sex prior to age 18 were significantly more likely to report that being a recipient of oral sex was the easiest way for them to reach orgasm with a partner after age 18 and they had a preference for oral sex if they had experienced an orgasm during oral sex prior to age 18