1,442 research outputs found

    Extended shells around B[e] stars - implications for B[e] star evolution

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    Aims. The position of B[e] stars in the upper left part of the Hertzsprung-Russell diagram creates a quandary. Are these stars young stars evolving onto the main sequence or old stars that are evolving off of it? Spectral characteristics suggest that B[e] stars can be placed into five subclasses and are not a homogeneous set. Such sub-classification is believed to coincide with varying origins and different evolutions. However, the evolutionary connection of B[e] stars – and notably sgB[e] – to other stars is unclear, particularly to evolved massive stars. We attempt to provide insight into the evolutionary past of B[e] stars. Methods. We performed an Hα narrow-band CCD imaging survey of B[e] stars, in the northern hemisphere. Prior to the current work, no emission-line survey of B[e] stars had yet been made, while only two B[e] stars appeared to have a shell nebula as seen in the Digital Sky Survey. Of nebulae around B[e] stars, only the ring nebula around MWC137 has been previously observed extensively. Results. In this presentation we report the findings from our narrow-band optical imaging survey of the environments of 25 B[e] stars. Of the objects surveyed, 7 show bipolar or uni- polar structures up to 15' across; 5 show faint, large, or filamentary shells; and 2 are compact planetary nebula-type systems. The most spectacular system observed is a large bipolar structure associated with MWC314. Conclusions. The possible links between B[e] stars and other evolved stars, implied by our observations, are investigated

    The Role of Metacognition in Visual Art Education

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    Metacognition is a conscious activity that occurs in the brain when an individual monitors or controls his or her thinking. Research in multiple fields has found that metacognition plays a significant role in a person’s learning. It is currently a popular trend in general education to teach students metacognitive strategies, and research has shown that it is a practical tool to boost student success. Moreover, metacognition is most effective when it is taught explicitly and regularly practiced by the students. There is a need for more research into the effectiveness of explicitly teaching metacognition in middle and high school visual arts classrooms. Art education has undergone architectural changes over the past few decades; as of late, it is moving towards a more open-ended approach which is demonstrated in current art standards. Based on the author’s student teaching experiences and the literature review of this thesis, she proposes what art curriculum could look like when metacognition and cognitive development are the focus of the classroom. She concludes that embedding metacognitive strategies in the visual art curriculum will help students develop critical thinking and self-reflective skills in addition to artistic skills

    Advance Directives Containing Pregnancy Exclusions: Are They Constitutional?

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    Every state has an advance directive statue that allows individuals to direct their health care in the event they become incompetent. Written into a majority of these statutes is a “pregnancy exclusion” that limits the effectiveness of the advance directive when the patient is a pregnant woman. The effect of the exclusion differs from state to state, and there is virtually no public awareness that pregnancy exclusions exist. This article analyzes the various pregnancy exclusions and explores whether a state\u27s interest in the fetus should take precedence over a woman\u27s right to refuse or terminate life support

    Summary of International Transport Energy Modeling Workshop

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    The NextSTEPS program at ITS-Davis convened a one-day workshop on international transportation energy modeling (iTEM), focused on comparing the frameworks and scenario projections from four major global transport models: -- Global Change Assessment Model (GCAM) by Pacific Northwest National Laboratory (PNNL) and ITS-Davis, -- MESSAGE-Transport (Model for Energy Supply Strategy Alternatives and their General Environmental Impact) by the International Institute for Applied Systems Analysis (IIASA), -- Mobility Model (MoMo) by the International Energy Agency, and -- Roadmap by the International Council on Clean Transportation (ICCT). Highlights: -- Projections of "baseline" global transportation energy use rise from 98 EJ in 2010 to 160-250 EJ by 2050. -- There are considerable differences in historical data for some modes, both globally and for individual countries (particularly non-OECD countries). Variability in estimates of transportation activity are in most cases much larger than energy differences. -- Global average vehicle ownership rates are projected to range from 270 to 450 per 1,000 people by 2050 with wide ranges across countries: 700-1,075 for the US by the middle of the century (US is around 700 today), 100-650 for China, and 80-380 for India across four models. -- All models rely mainly on GDP to estimate the future demand for freight and hold the base year modal shares (e.g. truck v. rail) roughly constant through 2050. In reality, future evolution will depend on characteristics of products (e.g. type of commodities) being shipped, technologies available for freight and their efficiencies, and policies and infrastructure. -- Current policy commitments toward EVs, PHEVs and H2FCVs (and thus baseline projections) maybe below the numbers suggested by iTEM models as required for meeting climate targets (e.g., 2 degrees C). -- Improvements in data quality and the representation of car ownership and use across the models were identified as priorities. Modeling transport energy use can either be done by estimating how far people travel and what mode of transportation they choose or by estimating how many vehicles there are and how far each one travels. These are complementary approaches, and in theory they should both lead to the same answer. The former approach, used in "service demand" models, seem more intuitive when one wants to model societal shifts in modes of transportation, either in emerging economies as they develop or in developed economies as they decarbonize; but collecting data on service demand is notoriously difficult. In contrast, vehicle stock models use readily-available vehicle sales data, but are harder to use in future-state, what-if scenarios (particularly in estimating modal shift behaviors) and thus require special attention by experts. The four iTEM models are different in terms of scope (GCAM and MESSAGE cover all sectors of the energy system vs. MoMo and Roadmap which cover transportation only) and model structure (GCAM and MESSAGE rely on internal drivers, particularly the costs of technology and travel, to project future changes whereas MoMo and Roadmap rely on experts' judgments and detailed analysis of technology and policies to drive long-term changes). Yet, owing to these differences, the models are highly complementary and in some cases can be used jointly to answer questions that no single model can tackle on its own. The following summary shares some of the comparisons and findings from the workshop

    Occupancy and habitat use by six species of forest ungulates on Tiwai Island, Sierra Leone

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    Forest ungulates in West Africa are common bushmeat species and are subject to habitat degradation through deforestation. Based on historical data, there are possibly 12 species of forest Bovidae and Tragulidae found in eastern Sierra Leone. We used camera trapping to assess occupancy by forest ungulates on and around a small protected area, Tiwai Island, Sierra Leone. We then assessed habitat over two field seasons during 2008–2011 for those species where we had sufficient numbers of detections. We detected 6 of 12 potential species and obtained enough data to further assess the habitat of two species. Species detected included the black duiker (Cephalophus niger), bongo (Tragelaphus eurycerus), bushbuck (Tragelaphus scriptus), Maxwell’s duiker (Philantomba maxwellii), water chevrotain (Hyemoschus aquaticus) and yellow-backed duiker (Cephalophus silvicultor). Among detected species, the bongo is considered near threatened. Several of the species not detected might be extirpated from the region, but for several species we found no records of them in the area. For the two species with sufficient detections for analysis, we found that Maxwell’s duikers were common throughout woody and swamp habitat and yellow-backed duikers preferred old growth forests with open understory. Despite widespread deforestation in Sierra Leone, a recent civil war and continued bushmeat trade, it appears that small wildlife refuges such as Tiwai Island continue to provide sanctuary for many of the forest ungulates of the region. Conservation implications: The Guinea Rainforest ecosystem of West Africa has undergone significant human impact and deforestation, negatively impacting all aspects of the biodiversity of the region. In addition, a long-standing civil war in Sierra Leone further exacerbated conservation concerns of many wildlife species. There are some recognised reserves in Sierra Leone, but small reserves managed by local people and conservation organisations have a role to play. Our work on Tiwai Island, along the Moa River in Sierra Leone, demonstrated that a significant proportion of the forest dwelling ungulate biodiversity of the region has been maintained in a small reserve despite isolation and effects of the war. Our work also suggests that Tiwai Island continues to have significant ecological value for ungulate conservation in the region and should be considered a model for establishment of other small reserves to help maintain the region’s biodiversity

    Building Social Capital in Forest Communities: Analysis of New Mexico\u27s Collaborative Forest Restorative Program

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    In part because of its emphasis on building social capital, the Collaborative Forest Restoration Program (CFRP) in New Mexico represents a unique experiment in public lands management. This study uses logit probability modeling to investigate what factors determined CFRP funding, which totaled $26 million between 2001 and 2006. Results reveal program preferences for projects that encourage collaboration and improve forest health, especially in poor counties. Negative determinants of funding include measures of small-diameter material utilization and whether a project takes place across multiple land jurisdictions. There is no evidence of bias toward funding any particular applicant type or land jurisdiction

    The IIASA Energy-Multi Criteria Analysis Tool (ENE-MCA)

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    Researchers at the International Institute for Applied Systems Analysis (IIASA), building on work carried out within the framework of the Global Energy Assessment (GEA), have developed an interactive web-based scenario analysis tool that permits the concurrent assessment of synergies and trade-offs between multiple energy objectives at the global scale. This software, known as the IIASA Energy-Multi Criteria Analysis Policy Tool (ENE-MCA), is designed to assist national policy makers in their strategic policy planning processes. The tool extends work undertaken for the GEA and, as such, is built on the extensive set of global energy and environmental scenarios that have been generated as part of the GEA process. This document serves as an introduction to the ENE-MCA tool and as a brief manual for the typical user
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