Rapid Savanna Response to Changing Precipitation Intensity

As the atmosphere warms, precipitation events are likely to become less frequent but more intense. While extensive efforts have been made to understand how changes in mean annual precipitation will affect plant growth, particularly in semi-arid systems, relatively little is known about how increasing precipitation intensity will affect plant growth and hydrologic cycles. A recent study by Kulmatiski and Beard (2013) found that small increases in precipitation intensity increased woody plant growth and decreased grass growth in a three-year experiment in a savanna system, Kruger National Park. Here we report results from the following two years of that experiment. Due to naturally large precipitation events, plant available water was similar between treatment and control plots in the last two years of the study allowing us to test woody plant and grass responses to treatment removal (i.e., legacy effects). Treatment effects on grass and tree growth disappeared within months of treatment removal. However, due to a legacy effect of treatments, tree mass was greater in treatment that control plots at the end of the experiment. Measurements of root recruitment and hydrological tracer uptake, but not root volume helped explain plant growth responses to treatments. Results suggest that savanna plants respond rapidly to changes in precipitation intensity, but because of legacy effects, occasional increases in precipitation intensity can result in long-term shrub encroachment

Emissão dia 21 de dezembro de 2013

Emissões - TemáticasPrograma produzido pela Universidade Aberta e Terra Líquida Filmes, emitido ao abrigo de uma parceria com a RTPComemorações dos 25 Anos da Universidade Aberta (UAb): Sessão dirigida a todos os funcionários e docentes da UAb, dia 2 de dezembro de 2013, na Academia das Ciências, Lisboa: Atribuição da medalha comemorativa aos colaboradores da UAb; Depoimentos de Margarida Carmo, representante dos funcionários da UAb, de Maria Leonor Machado de Sousa, primeira Vice-reitora da UAb, de Carla Oliveira, Vice-reitora da UAb, de José Bidarra, docente da UAb e de Maria Beatriz Rocha-Trindade, professora catedrática aposentada, da Universidade Aberta. Entrevista ao Reitor da Universidade Aberta, professor Paulo Dias, acerca das comemorações dos 25 Anos da Universidade Aberta e do “III Colóquio Luso-Brasileiro de Educação a Distância e Elearning”. “III Colóquio Luso-Brasileiro de Educação a Distância e Elearning”, no Pavilhão do Conhecimento, em Lisboa: Depoimentos de Lígia Pupatto, Secretária de Inclusão Digital do Ministério das Comunicações do Brasil, de João Carlos Teatini, diretor de Ensino a Distância da CAPES, de José Ferreira Gomes, Secretário Estado do Ensino Superior, de António Dias de Figueiredo, professor da Universidade de Coimbra e de Alexandra Okada, da Open University; Participação de Suyanne Tolentino, jornalista brasileira, colaboradora da equipa de reportagem da UAb; Depoimento de António Quintas-Mendes, diretor do Laboratório de Educação a Distância e Elearning (LEaD), da UAb; Clara Mendes e Filipe de Sousa, estudantes de Ciências da Comunicação, da Universidade Nova de Lisboa, falam da colaboração no evento; Depoimento da professora Lúcia Amante, da Comissão organizadora e docente da Universidade Aberta. [Notícias]: myMPeL 2013: 4.ª Conferência do Mestrado em Pedagogia do Elearning, da Universidade Aberta (UAb). O evento teve lugar na Universidade Aberta, em Lisboa e contou com a colaboração de Tony Bates, consultor internacional na área do Elearning e Doutor Honoris Causa da Universidade Aberta. Fugas: “A gramática é uma canção doce” = “La grammaire est une chanson douce”, de Erick Orsenna, com Susana Mântua, técnica superior da Universidade Aberta. A emissão inclui as habituais rubricas” Destaques” e “Cartaz “.info:eu-repo/semantics/publishedVersio

Double Occupancy Errors in Quantum Computing Operations: Corrections to Adiabaticity

We study the corrections to adiabatic dynamics of two coupled quantum dot spin-qubits, each dot singly occupied with an electron, in the context of a quantum computing operation. Tunneling causes double occupancy at the conclusion of an operation and constitutes a processing error. We model the gate operation with an effective two-level system, where non-adiabatic transitions correspond to double occupancy. The model is integrable and possesses three independent parameters. We confirm the accuracy of Dykhne's formula, a nonperturbative estimate of transitions, and discuss physically intuitive conditions for its validity. Our semiclassical results are in excellent agreement with numerical simulations of the exact time evolution. A similar approach applies to two-level systems in different contexts

Materials-based process tolerances for neutron generator encapsulation.

Variations in the neutron generator encapsulation process can affect functionality. However, instead of following the historical path in which the effects of process variations are assessed directly through functional tests, this study examines how material properties key to generator functionality correlate with process variations. The results of this type of investigation will be applicable to all generators and can provide insight on the most profitable paths to process and material improvements. Surprisingly, the results at this point imply that the process is quite robust, and many of the current process tolerances are perhaps overly restrictive. The good news lies in the fact that our current process ensures reproducible material properties. The bad new lies in the fact that it would be difficult to solve functional problems by changes in the process

Examining the Potential Disconnect Between Parents’ Perceptions and Reality Regarding the Physical Activity Levels of Their Children

Background: Parental support plays an important role in facilitating the participation of children in physical activity. However, there is evidence that parents overestimate their child’s level of physical activity – this may lead to inaction in promotion attempts by parents. This potential disconnect between parental perceptions and reality was recently the focus of the ‘Think Again’ social marketing campaign developed by PartipACTION. Purpose: To qualitatively explore parents’ perceptions of the Think Again advertisements, and the possible disconnect between perceptions and reality regarding their children’s physical activity levels. Method: Semi-structured interviews were conducted with 12 mothers and 12 fathers of children aged 5-11 years attending a supervised recreation class. A thematic analysis was applied to the collected data. Results: The advertisements were generally well received by the parents in serving as a reminder of how much physical activity their children should be getting. Less than half of parents believed their children were attaining physical activity guidelines although the majority believed they were sufficiently active given perceived time constraints for both them and their child. Most parents believed they could accurately estimate how active their child was but that other parents may have difficulty due to reliance on schools and organized recreation to provide opportunities for physical activity. Conclusion: PSAs have a role to play in increasing parental awareness of physical activity guidelines and communicating the importance of physical activity. More creative approaches will be needed to address the disconnect in the perceptions between sufficient and recommended levels of physical activity

Characterization of Cre recombinase models for the study of adipose tissue

The study of adipose tissue in vivo has been significantly advanced through the use of genetic mouse models. While the aP2-CreBI and aP2-CreSalk lines have been widely used to target adipose tissue, the specificity of these lines for adipocytes has recently been questioned. Here we characterize Cre recombinase activity in multiple cell populations of the major adipose tissue depots of these and other Cre lines using the membrane-Tomato/membrane-GFP (mT/mG) dual fluorescent reporter. We find that the aP2-CreBI and aP2-CreSalk lines lack specificity for adipocytes within adipose tissue, and that the aP2-CreBI line does not efficiently target adipocytes in white adipose depots. Alternatively, the Adiponectin-CreERT line shows high efficiency and specificity for adipocytes, while the PdgfRα-CreERUCL and PdgfRα-CreERJHU lines do not efficiently target adipocyte precursor cells in the major adipose depots. Instead, we show that the PdgfRα-Cre line is preferable for studies targeting adipocyte precursor cells in vivo

Tyre wear particles are toxic for us and the environment

This briefing paper discusses the current knowledge on the effects of tyre wear particles on our health and environment, highlights the need for an ambitious research agenda to build further understanding of the impacts on people and nature and develop solutions, and includes recommendations for policymakers

Dependence of the kinetic energy absorption capacity of bistable mechanical metamaterials on impactor mass and velocity

Using an alternative mechanism to dissipation or scattering, bistable structures and mechanical metamaterials have shown promise for mitigating the detrimental effects of impact by reversibly locking energy into strained material. Herein, we extend prior works on impact absorption via bistable metamaterials to computationally explore the dependence of kinetic energy transmission on the velocity and mass of the impactor, with strain rates exceeding $10^2$ s$^{-1}$. We observe a large dependence on both impactor parameters, ranging from significantly better to worse performance than a comparative linear material. We then correlate the variability in performance to solitary wave formation in the system and give analytical estimates of idealized energy absorption capacity under dynamic loading. In addition, we find a significant dependence on damping accompanied by a qualitative difference in solitary wave propagation within the system. The complex dynamics revealed in this study offer potential future guidance for the application of bistable metamaterials to applications including human and engineered system shock and impact protection devices

International education: a force for peace and cross-cultural understanding?

This paper discusses the notion that the international sojourn has the potential to transform sojourners into cultural mediators who carry the power to improve global relations. A year-long ethnographic study of the adjustment experiences of international postgraduate students in England revealed a universal early enthusiasm for cross-cultural contact that was matched by a widespread adoption of segregated patterns of interacting. The most common friendship networks were described by bonds with conationals, and yet all students attested to an increase in their cultural learning and mindfulness by the end of the sojourn. Nevertheless, intercultural competence was maximised only in those few students who pursued a multicultural strategy of interaction, leading the researcher to call on Higher Education Institutions to instigate policies to encourage lasting cross-cultural contact