987 resultados para 175-1


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We present a 5.3-Myr stack (the ''LR04'' stack) of benthic d18O records from 57 globally distributed sites aligned by an automated graphic correlation algorithm. This is the first benthic delta18O stack composed of more than three records to extend beyond 850 ka, and we use its improved signal quality to identify 24 new marine isotope stages in the early Pliocene. We also present a new LR04 age model for the Pliocene-Pleistocene derived from tuning the delta18O stack to a simple ice model based on 21 June insolation at 65 N. Stacked sedimentation rates provide additional age model constraints to prevent overtuning. Despite a conservative tuning strategy, the LR04 benthic stack exhibits significant coherency with insolation in the obliquity band throughout the entire 5.3 Myr and in the precession band for more than half of the record. The LR04 stack contains significantly more variance in benthic delta18O than previously published stacks of the late Pleistocene as the result of higher resolution records, a better alignment technique, and a greater percentage of records from the Atlantic. Finally, the relative phases of the stack's 41- and 23-kyr components suggest that the precession component of delta18O from 2.7-1.6 Ma is primarily a deep-water temperature signal and that the phase of d18O precession response changed suddenly at 1.6 Ma.

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Objective: Ocular allergy is a broad group of allergic conditions involving inflammation of the conjunctiva and the most common forms are seasonal allergic conjunctivitis (SAC; 90% of cases) and perennial allergic conjunctivitis (PAC; 5% of cases). The main symptom is ocular itching caused by mast cell degranulation leading to the release of histamine and other mediators such as tryptase. Tryptase is a neutral protease that is selectively concentrated in the secretory granules of human mast cells and has been shown to be a sensitive and specific marker of type I hypersensitivity reaction. The objective was to ascertain the best assay method for determining the tryptase levels in tear samples and whether this can be used to determine the efficacy of non-pharmacological treatments compared to no treatment or their combined effect with anti-allergic medication for SAC and PAC. Method: Thirty patients with a history of SAC were recruited into a randomised blind study during winter months when all the patients were asymptomatic. Suitability was determined by skin prick and conjunctival provocation tests. Patients were randomly assigned to either a non-pharmacological or a pharmacological Intervention group and received each test condition assigned to their group in a randomly assigned order. Symptoms were provoked by exposure to pollen in an environmental test chamber where the temperature, humidity and grass pollen levels were set to a high pollen count day. Tear samples were taken set intervals during the visit and then processed by enzyme linked immunosorbent assay (ELISA) for the detection of tryptase levels. Preliminary results: Results are still being analysed but the preliminary optimisation experiments tested four different ELISA systems; two indirect assays and two capture ‹sandwich› assays. The results suggest that in both sandwich assay systems non-specific binding occurred which could not be easily overcome. The indirect assay systems both showed specific reactions, and the sensitivity achieved was greater with the monoclonal than the polyclonal antibody. Using these findings the indirect assay system was optimised to provide a standardised system for measuring tryptase. Initial trials using human tear samples displayed tryptase levels between 23.1 and 175.1 ng/ml; levels which fall within the anticipated range for patients with SAC. Further statistical work is needed to determine whether tryptase levels vary between the treatments 75.

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A uniform chronology for foraminifera-based sea surface temperature records has been established in more than 120 sediment cores obtained from the equatorial and eastern Atlantic up to the Arctic Ocean. The chronostratigraphy of the last 30,000 years is mainly based on published d18O records and 14C ages from accelerator mass spectrometry, converted into calendar-year ages. The high-precision age control provides the database necessary for the uniform reconstruction of the climate interval of the Last Glacial Maximum within the GLAMAP-2000 project.