388 research outputs found
Subsurface mapping of Ellesmerian onlaps: Testing the opening of the Arctic Canada Basin
Since the advent of plate tectonics in the mid-1960\u27s the mechanism for formation of the majority of the world\u27s ocean basins has been solved. However, there are still several remaining tectonic conundrums, such as the origin of the Arctic Canada Basin. The most widely accepted tectonic hypothesis proposes a rotational opening of the basin after rifting along the Northern Alaskan-Canadian Arctic margins.;Subsurface mapping the Ellesmerian strata of Northern Alaska onlapping onto the Barrow Arch, a long-lived basement high, was carried out and then compared with mapped strata on Prince Patrick Island, Canada, to see if they aligned. These mapped onlaps appear to show a match between Northern Alaska and the Canadian Arctic, if Northern Alaska is rotated back clockwise by 60° about a Euler pole located at 68.9°N, 229°W. Along with recent gravity and magnetic anomaly data, all this new evidence would appear to be consistent with a rotational opening
The Effects of Verbal Fluency Interventions: Phonemic versus Semantic Fluency Outcomes in Parkinson\u27s Disease
Verbal fluency (VF) tasks are well-established and widely used tools in clinical assessment and research settings to evaluate executive functioning skills. They consist of verbally generating as many different items as possible that either begin with a specified letter (i.e., phonemic) or belong to a category (i.e., semantic) within 60 seconds. Due to deficits in executive functioning, individuals with Parkinson’s disease (PD) have increased difficulty with phonemic compared to semantic fluency. Although VF tasks are commonly used as intervention tools within speech-language pathology clinical practice, there is limited research investigating their therapeutic benefit. The purpose of this study was to investigate the effectiveness of a VF task intervention program at rehabilitating VF performances of an individual with PD. Additionally, this study investigated any effects of intervention on other measures of executive functioning. A quasi-experimental, pretest/posttest design was used. The 10-session intervention period focused on teaching and practicing the clustering and switching approach to VF tasks. Results revealed no significant changes in VF performances after intervention. Significant changes to other executive functioning measures validate the need for further investigation into VF tasks as therapeutic tools
The Westinghouse Series 1000 Mobile Phone: Technology and applications
Mobile satellite communications will be popularized by the North American Mobile Satellite (MSAT) system. The success of the overall system is dependent upon the quality of the mobile units. Westinghouse is designing our unit, the Series 1000 Mobile Phone, with the user in mind. The architecture and technology aim at providing optimum performance at a low per unit cost. The features and functions of the Series 1000 Mobile Phone have been defined by potential MSAT users. The latter portion of this paper deals with who those users may be
Insulated conducting cantilevered nanotips and two-chamber recording system for high resolution ion sensing AFM.
Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels
Institutional owners and competitive rivalry
Scholars have increasingly recognized the importance of institutional owners in
the life of the firm and have sought to explain how and when these owners influence
firm-level strategies. In spite of evidence that these owners can and do affect broad
strategies, there is little empirical support for the extent to which institutional investors
involve themselves at the level of strategic competitive actions that firms undertake. This
raises the question: "How do different types of institutional investors affect strategic
competitive activity between firms?" Further, owners have a unique bearing on
competitive activity insofar as they can simultaneously influence firms that are
competing with each other. Therefore another important question is: "How are the
relationships between institutional investors and strategic competitive activity affected
when those investors hold stakes in both the focal firm and their competitor?" Borrowing from the accounting literature, this dissertation classifies institutional
owners into three groups based on their historical trading behavior: transient, dedicated,
and quasi-indexer. Findings from examination of the ownership holdings and strategic
competitive activity of thirty-six Fortune 500 rivalries over the years 1997-2006 provide insight into these questions. High levels of dedicated institutional ownership are
associated with greater strategic competitive activity whereas high transient institutional
ownership is associated with low strategic competitive activity. The relationship between
dedicated ownership and strategic competitive activity is moderated by common
ownership of a focal firm and its rival. As dedicated ownership of the focal firm and its
rival increase together, strategic competitive activity is reduced. The results presented
here change the way we apply agency theory to explain firm governance. For competitive
dynamics researchers, this study points to a previously unexplored means by which firms
are motivated to engage, or not engage, in competitive activity. This study also has broad
implications for managers, investors, and policymakers
Social structure and the maintenance of biodiversity
Traditional ecological models assume well-mixed populations, where all members are equally likely to interact with one another. These models have been used successfully to explain competitive interactions; however, positive interactions such as intraspecific cooperation and interspecific facilitation cannot readily be captured. Previous work has highlighted the importance of spatial structure in explaining these behaviors as well as its role in maintaining biodiversity. These spatial structures have frequently been modeled using lattices, where all organisms have an equal number of interactions. Although these models capture the spatiality of interactions, natural populations are unlikely to follow such rigid patterns. There has been little work investigating the dynamics of populations with levels of social interactions that occur between these two extremes. In this work, we investigate the dynamics of a 3-strategy nontransitive system in populations with different social structures. We first describe how extending the neighborhood of interactions in traditional lattice models diminishes a population’s ability to maintain diversity. Populations are then moved to graphs where interactions are limited to cells within a defined distance of each other in Cartesian space. This method allows for a more fine-grained examination of the effects that increasing interactions have on maintaining diversity. Finally, we examine small world topologies and find that the introduction of random edges into the graph quickly disrupts the maintenance of diversity
Assessment Of Streamflow Predictions Generated Using Multimodel And Multiprecipitation Product Forcing
This study assesses streamflow predictions generated by two distributed hydrologic models, the Hillslope Link Model (HLM) and the National Water Model (NWM), driven by three radar-based precipitation forcing datasets. These forcing data include the Multi-Radar Multi-Sensor (MRMS), and the Iowa Flood Center\u27s single-polarization-based (IFC-SP) and dual-polarization-based (IFC-DP) products. To examine forcing-and model-dependent aspects of the representation of hydrologic processes, we mixed and matched all forcing data and models, and simulated streamflow for 2016–18 based on six forcing–model combinations. The forcing product evaluation using independent ground reference data showed that the IFC-DP radar-only product\u27s accuracy is comparable to MRMS, which is rain gauge corrected. Streamflow evaluation at 140 U.S. Geological Survey (USGS) stations in Iowa demonstrated that the HLM tended to perform slightly better than the NWM, generating streamflow with smaller volume errors and higher predictive power as measured by Kling–Gupta efficiency (KGE). The authors also inspected the effect of estimation errors in the forcing products on streamflow generation and found that MRMS\u27s slight underestimation bias led to streamflow underestimation for all simulation years, particularly with the NWM. The less biased product (IFC-DP), which has higher error variability, resulted in increased runoff volumes with larger dispersion of errors compared to the ones derived from MRMS. Despite its tendency to underestimate, MRMS showed consistent performance with lower error variability as reflected by the KGE. The dispersion observed from the evaluation metrics (e.g., volume error and KGE) seems to decrease as scale becomes larger, implying that random errors in forcing are likely to average out at larger-scale basins. The evaluation of simulated peaks revealed that an accurate estimation of peak (e.g., time and magnitude) remains challenging, as demonstrated by the highly scattered distribution of peak errors for both hydrologic models
Education for sustainable development: emerging themes from adopters of a declaration
Universities that sign the Talloires Declaration signify their commitment to education for sustainable development. This research explores whether the signification is a strategic desire to be seen to be doing the right thing, or a genuine commitment to enhancing sustainability and helping the environment. This semi-structured interview research involves communication with the sustainability managers in the majority of Talloires signified universities in Australia. Since Australia has a comparably high rate of commitment to the Talloires Declaration, the findings represent rich and deep insight into reasons and motivations that can inform the adoption process around the world. Applying institutional theory and related concepts of structuration, isomorphism, and signaling, the findings are analyzed to reveal the range of environmental initiatives and the underlying explanation of themes. Current strategies and future directions for universities are indicated. Findings are that higher education is a key mechanism in business and society for finding and harnessing knowledge-based solutions. The challenge is that institutionalization has created resistance to change through coercive, normative, and mimetic isomorphism, along with rhetoric. Structuration factors should be considered in the context of making positive changes for sustainability in the university sector
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