Conifer encroachment and removal in a Northern California oak woodland: influences on ecosystem physiology and biodiversity

Oregon white oak (Quercus garryana) woodlands across their range are becoming increasingly threatened by encroaching Douglas-fir encroachment (Pseudotsuga menziesii) as a result of fire exclusion. Using water potential (Ψ), stomatal conductance (gs), xylem water stable isotopes (dD), and three metrics of biodiversity, this study investigates the effects of conifer encroachment and removal at the ecosystem-scale. The study was set in an Oregon white oak woodland in northern California and compared three levels of encroachment before and after conifer removal. Findings indicate that heavily encroached stands have the least amount of water stress and gas exchange. A moderate level of conifer encroachment appears to buffer water stress and support high productivity throughout the growing season. Trends in Y and gs suggest that coniferous shade improves oak water status via reduced evapotranspiration but limits productivity. Further, xylem water dD confirms that oaks and Douglas-firs are likely not directly competing for water, as oaks appear to use a relatively deeper water source. Thus, physiological results indicate that oak mortality to encroachment is likely light due to light, not water, limitation. Following conifer removal, moderately encroached stands did not respond dramatically during the first and second post-treatment years. However, heavily encroached stands increased gas exchange in both post-treatment years compared to unthinned counterparts. For ecosystem biodiversity, plant and bird diversity did not meaningfully differ among encroachment levels or between treatments, but mammal diversity was greatest in encroached stands. Collectively, findings from this work demonstrate that conifer removal is physiologically beneficial for light-limited oaks and that heavier thinning treatments are likely needed to yield long-term responses and influence biodiversity

Cleft Extensions and Quotients of Twisted Quantum Doubles

Given a pair of finite groups $F, G$ and a normalized 3-cocycle $\omega$ of $G$, where $F$ acts on $G$ as automorphisms, we consider quasi-Hopf algebras defined as a cleft extension $\Bbbk^G_\omega\#_c\,\Bbbk F$ where $c$ denotes some suitable cohomological data. When $F\rightarrow \overline{F}:=F/A$ is a quotient of $F$ by a central subgroup $A$ acting trivially on $G$, we give necessary and sufficient conditions for the existence of a surjection of quasi-Hopf algebras and cleft extensions of the type $\Bbbk^G_\omega\#_c\, \Bbbk F\rightarrow \Bbbk^G_\omega\#_{\overline{c}} \, \Bbbk \overline{F}$. Our construction is particularly natural when $F=G$ acts on $G$ by conjugation, and $\Bbbk^G_\omega\#_c \Bbbk G$ is a twisted quantum double $D^{\omega}(G)$. In this case, we give necessary and sufficient conditions that Rep($\Bbbk^G_\omega\#_{\overline{c}} \, \Bbbk \overline{G}$) is a modular tensor category.Comment: LaTex; 14 page

A qualitative analysis of military couples with high and low trauma symptoms and relationship distress levels

The purpose of the current study was to understand the experiences of a subset of military couples regarding the effects of war deployment on couple functioning. This study utilized the core “couple functioning” variables included in the Couple Adaptation to Traumatic Stress Model (Nelson Goff & Smith, 2005) as sensitizing concepts to guide the qualitative analysis process. Participant interviews (n = 15 couples, 30 total participants) were divided into subgroups according to high and low trauma symptom and relationship satisfaction scale scores. Five primary themes were identified in the results: communication, conflict management, roles, support/nurturance, and post-traumatic growth. Overall, highly satisfied couples and those with the lowest levels of traumatic stress symptoms reported more positive relationship functioning in the identified areas, while couples reporting higher traumatic stress symptoms and lower relationship satisfaction indicated varied or inconsistent qualitative results. Clinical and research implications for military couples also are identified

Geological investigation of palaeotsunamis in the Samoan islands: interim report and research directions

The Komandorsky seismic gap has distinctive boundaries and a length of 650 km. Its period of “seismic silence” comes close to the maximum recurrence interval for great earthquakes in the Aleutian Island Arc - the stress concentration here probably having reached the critical value. So,estimation of possible earthquake and tsunami characteristics within this gap becomes a significant problem. The closest analog of a similar gap is the area where the 2004 Sumatra-Andaman catastrophic event occurred. Thus, for the present study we used the same modeling scheme as we used for that event. It was assumed that a source length of 650 km, consisting of 9 blocks, and an earthquake with a moment magnitude MW=8.5. Several block motion scenarios were considered. The tsunami generation and propagation in the Pacific Ocean and the possible wave characteristics on near and far-field coasts were estimated. Modeling of such an event showed that the wave heights on different Pacific coasts will vary from 3 to 9 meters. A tsunami wave with a 9-meter height is capable in causing significant loss of human life and economic damage.© 2013, Tsunami Society International

Environmental impacts during geothermal development: Some examples from Central America

The impacts of geothermal development projects are usually positive. However, without appropriate monitoring plans and mitigation actions firmly incorporated into the project planning process, there exists the potential for significant negative environmental impacts. The authors present five examples from Central America of environmental impacts associated with geothermal development activities. These brief case studies describe landslide hazards, waste brine disposal, hydrothermal explosions, and air quality issues. Improved Environmental Impact Assessments are needed to assist the developing nations of the region to judiciously address the environmental consequences associated with geothermal development

A Single Dose of Nicotine Enhances Reward Responsiveness in Nonsmokers: Implications for Development of Dependence

Background: Tobacco smoking, driven by the addictive properties of nicotine, is the most prevalent preventable cause of death in the Western world. Accumulated evidence suggests that nicotine may increase appetitive responding for nondrug incentives in the environment. Methods: To test this hypothesis, we conducted a randomized, double-blind, placebo-controlled, crossover study of the effect of a single dose of transdermal nicotine on reward responsiveness in 30 psychiatrically healthy nonsmokers. A novel signal detection task in which correct responses were differentially rewarded in a 3:1 ratio was used to assess the extent to which participants modulated their behavior as a function of reward. Results: Despite expected adverse effects such as nausea, nicotine significantly increased response bias toward the more frequently rewarded condition, at the expense of accuracy, independent of effects on attention or overall vigilance. Additionally, response bias on placebo was greater in participants who received nicotine in the first session, indicating that an effect of nicotine on reward responsiveness or reward-based learning persisted for at least 1 week. Conclusions: These findings suggest that a single dose of nicotine enhances response to non-drug-related rewards in the environment, with lasting effects. This effect may contribute to reinforcement of early smoking behavior and development of nicotine dependence.Psycholog