37,156 research outputs found

    Determination of water content using mass spectrometry

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    Mass spectrometer is used to measure small quantities of water present in different materials. System has been applied in measuring water and gases desorbed from microcircuitry insulation, can also be used with foods, polymeric materials, and organic solvents

    Dynamic delta method for trace gas analysis

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    Method has been developed in which measurements are made only over viscous flow range, eliminating fractionation before the molecular leak and problems due to surface elution

    Enhanced dielectrophoresis of nanocolloids by dimer formation

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    We investigate the dielectrophoretic motion of charge-neutral, polarizable nanocolloids through molecular dynamics simulations. Comparison to analytical results derived for continuum systems shows that the discrete charge distributions on the nanocolloids have a significant impact on their coupling to the external field. Aggregation of nanocolloids leads to enhanced dielectrophoretic transport, provided that increase in the dipole moment upon aggregation can overcome the related increase in friction. The dimer orientation and the exact structure of the nanocolloid charge distribution are shown to be important in the enhanced transport

    Degradation and breakdown characteristics of thin MgO dielectric layers

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    MgO has been suggested as a possible high-k dielectric for future complementary metal-oxide semiconductor processes. In this work, the time dependent dielectric breakdown (TDDB) characteristics of 20 nm MgO films are discussed. Stress induced leakage current measurements indicate that the low measured Weibull slopes of the TDDB distributions for both n-type and p-type devices cannot be attributed to a lower trap generation rate than for SiO2. This suggests that much fewer defects are required to trigger breakdown in MgO under voltage stress than is the case for SiO2 or other metal-oxide dielectrics. This in turn explains the progressive nature of the breakdown in these films which is observed both in this work and elsewhere. The reason fewer defects are required is attributed to the morphology of the films

    Lifetime Adherence to Physical Activity Recommendations and Fall Occurrence in Community-dwelling Older Adults: a Retrospective Cohort Study

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    Falling is a major health concern for community-dwelling older adults. Regular physical activity has been proposed to prevent falls. The aim of this study was to assess whether the achievement of the 2004 UK Department of Health physical activity recommendations over a lifetime had a protective effect against falling in older people. 313 community-dwelling older adults completed a questionnaire about lifetime physical activity and fall occurrence. There were significantly fewer falls in those who had led an active lifestyle compared to those who had not (χ2Yates=4.568, p=0.033), with a lower relative risk of fall occurrence for the active respondents (RR=0.671) compared to the inactive (RR=1.210). Of those who were sufficiently active in their early adulthood, the decade where there was the biggest decrease in remaining active enough was in the 60s. It is concluded that an active lifestyle may have decreased the likelihood of having a fall in older ag

    Confinement effects in a guided-wave interferometer with millimeter-scale arm separation

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    Guided-wave atom interferometers measure interference effects using atoms held in a confining potential. In one common implementation, the confinement is primarily two-dimensional, and the atoms move along the nearly free dimension under the influence of an off-resonant standing wave laser beam. In this configuration, residual confinement along the nominally free axis can introduce a phase gradient to the atoms that limits the arm separation of the interferometer. We experimentally investigate this effect in detail, and show that it can be alleviated by having the atoms undergo a more symmetric motion in the guide. This can be achieved by either using additional laser pulses or by allowing the atoms to freely oscillate in the potential. Using these techniques, we demonstrate interferometer measurement times up to 72 ms and arm separations up to 0.42 mm with a well controlled phase, or times of 0.91 s and separations of 1.7 mm with an uncontrolled phase.Comment: 14 pages, 6 figure

    The availability, cost, limitations, learning curve and future of robotic systems in urology and prostate cancer surgery

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    Robot-assisted surgical systems (RASS) have revolutionised the management of many urological conditions over the last two decades with robot-assisted radical prostatectomy (RARP) now being considered by many to be the preferred surgical approach. Intuitive Surgical has dominated the market during this time period with successive iterations of the da Vinci model. The expiration of patents has opened the RASS market and several new contenders have become available or are currently in development. This comprehensive narrative review aims to explore the merits of each robotic system as well as the evidence and barriers to their use. The newly developed RASS have increased the versality of robotic surgical systems to a wider range of settings through advancement in technology. The increased competition may result in an overall reduction in cost, broadening the accessibility of RASS. Learning curves and training remain a barrier to their use, but the situation appears to be improving through dedicated training programmes. Outcomes for RARP have been well investigated and tend to support improved early functional outcomes. Overall, the rapid developments in the field of robot-assisted surgery indicate the beginning of a promising new era to further enhance urological surgery
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