1,325 research outputs found

    Habit, aggregation and long memory: evidence from television audience data

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    Many economic outcomes appear to be influenced by habit or commitment, giving rise to persistence. In cases where the decision is binary and persistent, the aggregation of individual time series can result in a fractionally integrated process for the aggregate data. Certain television programmes appear to engender commitment on the part of viewers and the decision to watch or not is clearly binary. We report an empirical analysis of television audience data and show that these series can be modelled as I(d) processes. We also investigate the proposition that temporal aggregation of a fractionally-integrated series leaves the value of d unchanged.

    Amino acid racemization reveals differential protein turnover in osteoarthritic articular and meniscal cartilages

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    INTRODUCTION: Certain amino acids within proteins have been reported to change from the L form to the D form over time. This process is known as racemization and is most likely to occur in long-lived low-turnover tissues such as normal cartilage. We hypothesized that diseased tissue, as found in an osteoarthritic (OA) joint, would have increased turnover reflected by a decrease in the racemized amino acid content. METHODS: Using high-performance liquid chromatography methods, we quantified the L and D forms of amino acids reported to racemize in vivo on a biological timescale: alanine, aspartate (Asp), asparagine (Asn), glutamate, glutamine, isoleucine, leucine (Leu), and serine (Ser). Furthermore, using a metabolically inactive control material (tooth dentin) and a control material with normal metabolism (normal articular cartilage), we developed an age adjustment in order to make inferences about the state of protein turnover in cartilage and meniscus. RESULTS: In the metabolically inactive control material (n = 25, ages 13 to 80 years) and the normal metabolizing control material (n = 19, ages 17 to 83 years), only Asp + Asn (Asx), Ser, and Leu showed a significant change (increase) in racemization with age (P < 0.01). The age-adjusted proportions of racemized to total amino acid (D/D+L expressed as a percentage of the control material) for Asx, Ser, and Leu when compared with the normal articular cartilage control were 97%, 74%, and 73% in OA meniscal cartilage and 97%, 70%, and 78% in OA articular cartilage. We also observed lower amino acid content in OA articular and meniscal cartilages compared with normal articular cartilage as well as a loss of total amino acids with age in the OA meniscal but not the OA articular cartilage. CONCLUSIONS: These data demonstrate comparable anabolic responses for non-lesioned OA articular cartilage and OA meniscal cartilage but an excess of catabolism over anabolism for the meniscal cartilage

    Evidence for Lysosomal Enzymes in Acanthamoeba and Their Activity Changes During Encystment

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    Author Institution: Graduate Program in Zoology and Department of Microbiology, The Ohio State UniversityAssays on cell-free homogenates of Acanthamoeba castellanii reveal that the three hydrolases, acid phosphatase (APase), acid deoxyribonuclease, and acid ribonuclease (RNase), possess pH optima of 5.0, 4.8, and 5.2, respectively. These enzymes exhibit an enhanced sedimentation at 20,000 x g when sucrose is in the homogenizing buffer. Treatment of homogenates with Triton X-100 increases total enzyme activity. These results suggest that the enzymes are particle-bound in lysosomes. During encystment there is a differential decrease in the activity per cell of all three enzymes, with RNase decreasing most rapidly and APase least rapidly. The specific activity of APase increases during encystment even though its activity per cell gradually decreases

    Multi-partnership mangrove rehabilitation of Dasol Bay strategies and results

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    The coastal waters and shoreline of Luzon Province, the Philippines, have not been spared the loss of large tracks of mangrove forest. A multi-partnership coastal resource management project was implemented in 2005 to mitigate further degradation of the ecosystem through rehabilitation of mangrove forests in the Dasol Bay area of Pangasinan in northern Luzon. This paper presents a snapshot of results from this continuing effort and expectations for future initiatives in the area. The work is supported by Tanggol Kalikasan (Defense of Nature), with special support from the mayor’s office of the Dasol local government unit (LGU) including the Dasol municipal agriculture office, and Washington State University’s Office of International Research and Development. The authors built on a coastal resources database generated from a project-supported rapid resource assessment of Dasol Bay. Educating stakeholders about mangrove rehabilitation has been found to have an early and encouraging impact. Institutionalization through use of a structure that involves the community, an NGO, a university and individuals has helped partners meet goals. Results point to early successes from increasing environmental awareness and encouraging local participation that subsequently (1) allows effective constituency-building; (2) eases the integration of technical experts into decision-making processes; (3) provides a mechanism to channel innovative ideas and technologies; and (4) promotes learning by seeing and doing. This paper describes how the design and implementation of the Dasol Bay project promotes adaptive resource management, improves opportunities for effective governance and generates greater public support for rehabilitation of the mangrove forest. The project’s participatory community-based approach engages stakeholders in direct project implementation and leads to continuously increasing involvement by members of the community. Environmental awareness and local participation are hallmarks of this effort. Insights are provided into the future of the Multi-partnership Mangrove Rehabilitation of Dasol Bay Project (Dasol 1) and its sister project, Upland and Rural-Urban Ecosystem Management for Dasol Bay Project (Dasol 2), begun in 2006

    Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acoustic–trawl surveys

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    The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the “northern stock” since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stre
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