4,751 research outputs found

    The magnetization of sediment cores from the eastern basin of the North Atlantic Ocean

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    The magnetization of sediment from the eastern basin of the North Atlantic Ocean is due to magnetite. The variation of the directions of magnetization due in cores from the abyssal plains depends upon the sedimentary features which are the result of turbidity current deposition. The change in the inclination in the cores from the abyssal hills and mountains which rise from, or which surround, the Iberia plain suggests that there may be an effect dur to consolidation. The magnetic susceptibility of the sediment depends upon the amount of magnetic present and its size distribution. One test on one core suggests instability and no correlation has been found between the directions of magnetization of adjacent cores

    The effect of external forces on discrete motion within holographic optical tweezers

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    Holographic optical tweezers is a widely used technique to manipulate the individual positions of optically trapped micron-sized particles in a sample. The trap positions are changed by updating the holographic image displayed on a spatial light modulator. The updating process takes a finite time, resulting in a temporary decrease of the intensity, and thus the stiffness, of the optical trap. We have investigated this change in trap stiffness during the updating process by studying the motion of an optically trapped particle in a fluid flow. We found a highly nonlinear behavior of the change in trap stiffness vs. changes in step size. For step sizes up to approximately 300 nm the trap stiffness is decreasing. Above 300 nm the change in trap stiffness remains constant for all step sizes up to one particle radius. This information is crucial for optical force measurements using holographic optical tweezers

    Performance of a reflectometric technique for serum alanine aminotransferase determinations

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    The Ames Seralyzer uses solid phase chemistry coupled with reflectance spectroscopy to measure levels of serum alanine aminotransferase (serum ALT). The study reported here was carried out to evaluate the performance of the Seralyzer method compared to conventional analyses carried out on a Coulter Dacos discrete random access analyser using Boehringer (BCL) reagents conforming to SCE specications at 37° C. Clinically acceptable accuracy and precision were obtained. The effect of bilirubin and haemoglobin on the test was investigated. Increased levels of bilirubin in sera did not affect the estimation but the presence of high haemoglobin levels produced significant interference. The overall practicality of the Seralyzer was assessed and the method was found to be particularly suitable for the estimation of urgent or high risk samples in the laboratory or for use by suitably trained personnel in other clinical areas

    Emergence of long-range order in BaTiO3 from local symmetry-breaking distortions

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    By using a symmetry motivated basis to evaluate local distortions against pair distribution function data (PDF), we show without prior bias, that the off-centre Ti displacements in the archetypal ferroelectric BaTiO3 are zone centred and rhombohedral-like in nature across its known ferroelectric and paraelectric phases. With our newly-gained insight we construct a simple Monte Carlo (MC) model which captures our main experimental findings and demonstrate how the rich crystallographic phase diagram of BaTiO3 emerges from correlations of local symmetry-breaking distortions alone. Our results strongly support the order-disorder picture for these phase transitions, but can also be reconciled with the soft-mode theory of BaTiO3 that is supported by some spectroscopic techniques.Comment: 5 pages, 3 figure

    Resveratrol given intraperitoneally does not inhibit the growth of high-risk t(4;11) acute lymphoblastic leukemia cells in a NOD/SCID mouse model.

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    The efficacy of resveratrol as a preventive agent against the growth of t(4;11) acute lymphoblastic leukemia (ALL) was evaluated in NOD.CB17-Prkdcscid/J mice engrafted with the human t(4;11) ALL SEM cell line. SEM cells were injected into the tail vein and engraftment was monitored by flow cytometry. Once engraftment was observed, mice were injected intraperitoneally with resveratrol (10 mg/kg body weight) dissolved in dimethylsulfoxide (DMSO) or DMSO alone (control) every other day, or vincristine (0.5 mg/kg body weight) 3 times per week for 4 weeks (n=16 per group). Comparisons of the percent of human leukemia cells in blood and survival curves showed resveratrol did not inhibit progression of the disease. Liquid chromatography-tandem mass spectrometry analyses of mouse sera showed resveratrol was rapidly metabolized to glucuronidated and sulfated forms 1 h post-injection, with low to no resveratrol or metabolites observed in sera by 24-48 h. These data indicate that in contrast to findings in in vitro models, parenterally administered resveratrol does not have potential as a preventive agent against high risk t(4;11) ALL

    Metatarsophalangeal joint pain in psoriatic arthritis: a cross-sectional study

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    Methods. Thirty-four consecutive patients with PsA (mean age 45.3 years, 65% female, mean disease duration 9.9 years) and 22 control participants (mean age 37.9 years, 64% female) underwent clinical and US examination to determine the presence of pain, swelling, synovitis, erosions, effusions and submetatarsal bursae at the MTP joints. Mean barefoot peak plantar pressures were determined at each MTP joint. Levels of pain, US-determined pathology and peak pressures were compared between groups. Binary logistic regression was used to identify demographic, clinical examination-derived, US-derived and plantar pressure predictors of pain at the MTP joints in the PsA group. Results. The presence of pain, deformity, synovitis, erosions (P < 0.001) and submetatarsal bursae and peak plantar pressure at MTP 3 (P < 0.05) were significantly higher in the PsA group. MTP joint pain in PsA was independently predicted by high BMI, female gender and the presence of joint subluxation, synovitis and erosion. Conclusion. These results suggest local inflammatory and structural factors, together with systemic factors (gender, BMI), are predominantly responsible for painful MTP joints in PsA, with no clear role for plantar pressure characteristics
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