398 resultados para Tyler Burge
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Three metamorphic aureoles around intrusions of the Caledonian 'Newer Granite' suite are described. Each represents a different orogenic environment. The Strontian complex is intruded into sillimanite grade Moinian metasediments at the core of the orogen. The aureole comprises three zones; a transitional muscovite + sillimanite + K-feldspar zone, a sillimanite + K-feldspar zone and an inner cordierite + K-feldspar zone. Contact migmatization occurs in the inner part of the aureole. Zoning profiles from garnets in both regional and aureole assemblages show retrograde Mn-rich rims. Fe and Mg compositions are re-equilibrated to contact conditions. Apparent re-equilibration of Ca compositions results from increasingly ideal solid solution behaviour of Ca in plagioclase and garnet with increasing temperature. Temperatures of 690°C at 4.1 kbar (XH2O = 0.53) are estimated in the cordierite + K-feldspar zone, dropping to 630°C (XH2O = 0.69) at the sillimanite + K-feldspar isograd. The zones increase in width to the east, influenced by the regional thermal gradient at the time of intrusion. The timer-scale of the contact event, t2, relative to the regional, tl, - is estimated as t2/t1 = 101.1+ -0.7 and is consistent with Intrusion at an early stage of regional uplift and cooling. The Foyers complex intrudes Moinian rocks at a higher structural level. Regional assemblages range from garnet to sillimanite grade. Three contact zones are recognised; a sillimanite zone, a sillimanite + K-feldspar zone and an inner cordierite + K-feldspar zone. The limit of the aureole is marked by the breakdown of garnet which shows disequilibrium, both texturally, and in complex zoning profiles, within it. Temperatures of 660°C at 3.9 kbar (XH20 = 0.14) are estimated in the cordierite + K-feldspar zone? The Dalbeattie complex is at the margin of the orogen, intruded into low grade Silurian metasediments. Two zones are recognised; a biotite zone and an inner hornblende zone. Cordierite and diopside are present in the inner zone.
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Spoken language comprehension is known to involve a large left-dominant network of fronto-temporal brain regions, but there is still little consensus about how the syntactic and semantic aspects of language are processed within this network. In an fMRI study, volunteers heard spoken sentences that contained either syntactic or semantic ambiguities as well as carefully matched low-ambiguity sentences. Results showed ambiguity-related responses in the posterior left inferior frontal gyrus (pLIFG) and posterior left middle temporal regions. The pLIFG activations were present for both syntactic and semantic ambiguities suggesting that this region is not specialised for processing either semantic or syntactic information, but instead performs cognitive operations that are required to resolve different types of ambiguity irrespective of their linguistic nature, for example by selecting between possible interpretations or reinterpreting misparsed sentences. Syntactic ambiguities also produced activation in the posterior middle temporal gyrus. These data confirm the functional relationship between these two brain regions and their importance in constructing grammatical representations of spoken language.
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From a Social Identity Theory perspective, organisational identification arises through a cognitive process of self-categorisation. As a consequence a person need not have a formal relationship with an organisation in order to identify with it. In this conceptual paper, the authors draw on this proposal to argue that future members are capable of identifying with an organisation prior to entry, and that this initial pre-entry identification could contribute to a person’s subsequent post-entry organisational identification. The paper further suggests that because no distinction need be drawn between organisational identification in current and future members, we might expect to find the same antecedents of identification in both instances. The group engagement model (Tyler and Blader 2003) is called on to propose that when a future member experiences pride in, and respect from, an organisation before they join, this should positively influence their pre-entry organisational identification. The authors explore the managerial implications of these propositions, and argue that an organisation’s actions and practices that have been shown to influence a post-entry organisational identification should have an equivalent impact on future members’ organisational identification when observed during the pre-entry period. Two examples of such practices, organisational support and organisational communication, are used to illustrate this suggestion and a number of ways are discussed through which these practices may be experienced by a person before they join an organisation.
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Examining complete gene knockouts within a viable organism can inform on gene function. We sequenced the exomes of 3222 British Pakistani-heritage adults with high parental relatedness, discovering 1111 rare-variant homozygous genotypes with predicted loss of gene function (knockouts) in 781 genes. We observed 13.7% fewer than expected homozygous knockout genotypes, implying an average load of 1.6 recessive-lethal-equivalent LOF variants per adult. Linking genetic data to lifelong health records, knockouts were not associated with clinical consultation or prescription rate. In this dataset we identified a healthy PRDM9 knockout mother, and performed phased genome sequencing on her, her child and controls, which showed meiotic recombination sites localized away from PRDM9-dependent hotspots. Thus, natural LOF variants inform upon essential genetic loci, and demonstrate PRDM9 redundancy in humans.
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Agency costs are said to arise as a result of the separation of ownership from control inherent in the corporate form of ownership. One such agency problem concerns the potential variance between the time horizons of principal shareholders and agent managers. Agency theory suggests that these costs can be alleviated or controlled through performance-based Chief Executive Officer (CEO) contracting. However, components of a CEO's compensation contract can exacerbate or mitigate agency-related problems (Antle and Smith, 1985). According to the horizon hypothesis, a self-serving CEO reduces discretionary research and development (R&D) expenditures to increase earnings and earnings-based bonus compensation. Agency theorists contend that a CEO's market-based compensation component can mitigate horizon problems. This study seeks to determine whether there is a relationship between CEO earnings- and market-based compensation components and R&D expenditures in the largest United States industrial firms from 1987 to 1993.^ Consistent with the horizon hypothesis, results provide evidence of a negative and statistically significant relationship between CEO cash compensation (i.e., salary and bonus) and the firm's R&D expenditures. Consistent with the expectations of agency theory, results provide evidence of a positive and statistically significant relationship between market-based CEO compensation and R&D.^ Further results of this study provide evidence of a positive and statistically significant relationship between CEO tenure and the firm's R&D expenditures. Although there is a negative relationship between CEO age and the firm's R&D, it was not statistically significant at the 0.5 level. ^
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Deafness is an invisible handicap which makes education difficult due to its effect on language acquisition and development, speech acquisition, and ability to communicate with others. Teachers of students who are hearing impaired have been at odds for more than a century as to the best method of communication to use in teaching students who are hearing impaired, and in providing these students with communication systems that will enable them to be effective communicators. This dissertation utilized qualitative research methods to analyze whether the Dade County Public Schools Procedures for Providing Special Education for Exceptional Students-Hearing Impaired (DCPS), (1976-77; 1992-93) show evidence of an appropriate curriculum and instructional program that is responsive to the conditions facing exceptional education students identified as hearing impaired. Results indicate that many of the curriculum and instructional program requirements are not identified nor described when analyzed by Tyler's "Rationale" for Curriculum and Stufflebeam's Improvement-Oriented Evaluation Model, better known as Stufflebeam's CIPP Model. Recommendations to improve and enhance programs for students who are hearing impaired are offered based on this analysis. ^
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The relationship between reef corals and endosymbiotic dinoflagellates is fundamental to the existence of coral reefs. To evaluate the fidelity of coral-Symbiodinium mutualisms, corals maintained in aquaria for years were analyzed by denaturant gradient gel electrophoresis (DGGE). Comparing Symbiodinium populations of captive aquarium colonies with known associations in nature is a practical way of examining partner flexibility. The finding of "normal" symbiont populations in corals existing under highly variable conditions supports the premise that most coral colonies possess stable associations. High sensitivity real-time PCR (rtPCR) was used to evaluate background populations of the putatively stress-tolerant Symbiodinium D in reef corals of the Caribbean. Analyses of samples collected during periods of environmental stability indicate the ability of Symbiodinium D to associate with a wider diversity of host taxa than previously recognized. To gain a broader perspective with regard to the ecology of Symbiodinium D1a, rtPCR and DGGE were used to evaluate the symbiont populations of reef corals from Barbados before and after the 2005 mass coral bleaching. Background populations were observed in 56% of the host genera prior to observations of bleaching. These findings indicate that 'stress', not 'bleaching', caused the displacement of 'natural' symbiont population and the opportunistic proliferation of D1a in many host taxa. Of the 12 host taxa monitored before and after the bleaching event, there was a 40% increase in colonies hosting Symbiodinium D1a. Together, these studies elucidate the mechanism responsible for recent observations reporting the emergence of Symbiodinium D following thermal disturbances. These observations are now most easily explained as the disproportionate growth of existing in hospite symbiont populations, rather than novel symbiont acquisition subsequent to bleaching. To evaluate the comparative "fitness" of corals able to host multiple symbiont types, rates of calcification were measured in P. verrucosa hosting either Symbiodinium C1b-c or D1 at elevated temperature. Rates of calcification decreased significantly for both host-symbiont combinations, but differences attributable to symbiont composition were not detected. This research improves our knowledge of the symbiosis biology and ecology of reef corals and contributes information necessary to most accurately predict the response of these ecosystems to global climate changes.
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In September of 2010, Brewer's Bay reef, located in St. Thomas (U.S. Virgin Islands), was simultaneously affected by abnormally high temperatures and the passage of a hurricane that resulted in the mass bleaching and fragmentation of its coral community. An outbreak of a rapid tissue loss disease among coral colonies was associated with these two disturbances. Gross lesion signs and lesion progression rates indicated that the disease was most similar to the Caribbean coral disease white plague type 1. Experiments indicated that the disease was transmissible through direct contact between colonies, and five-meter radial transects showed a clustered spatial distribution of disease, with diseased colonies being concentrated within the first meter of other diseased colonies. Disease prevalence and the extent to which colonies were bleached were both significantly higher on unattached colony fragments than on attached colonies, and disease occurred primarily on fragments found in direct contact with sediment. In contrast to other recent studies, disease presence was not related to the extent of bleaching on colonies. The results of this study suggest that colony fragmentation and contact with sediment played primary roles in the initial appearance of disease, but that the disease was capable of spreading among colonies, which suggests secondary transmission is possible through some other, unidentified mechanism.
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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.
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The major objectives of this thesis were to determine if foam rolling had any effect on antagonist muscle activation and whether those changes would alter muscular co-activation patterns. The results from this thesis along with current literature will help clinicians to develop adequate exercise prescription for rehabilitative and pre-activity purposes. The existing literature has shown that foam rolling or roller massagers can increase range of motion (ROM), improve performance, and alter pain perception, however little research exists regarding changes in muscle activation following foam rolling. This study developed a reliable method for measuring muscle activation around the knee joint and using that method found that foam rolling the quadriceps can impair hamstrings muscle activation likely due to greater levels of perceived pain when rolling the quadriceps.
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Acknowledgments Alexander Dürre was supported in part by the Collaborative Research Grant 823 of the German Research Foundation. David E. Tyler was supported in part by the National Science Foundation grant DMS-1407751. A visit of Daniel Vogel to David E. Tyler was supported by a travel grant from the Scottish Universities Physics Alliance. The authors are grateful to the editors and referees for their constructive comments.