6,051 research outputs found
Serum hormones in boys prenatally exposed to polychlorinated biphenyls and dibenzofurans.
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Gender-related decrease in Raven’s Progressive Matrices scores in children prenatally exposed to polychlorinated biphenyls and related contaminants.
No full textEffect of prenatal PCB exposure on cognitive development in children: A longitudinal study in Taiwan.
No full textA three-dimensional hybrid LES-acoustic analogy method for predicting open-cavity noise
No full textA three-dimensional (3D) hybrid LES-acoustic analogy method for computational
aeroacoustics (CAA) is presented for the prediction of open-cavity noise. The method uses
large-eddy simulation (LES) to compute the acoustic source while the Ffowcs Williams-
Hawkings (FW-H) acoustic analogy is employed for the prediction of the far-field sound. As a
comparison, a two-dimensional (2D) FW-H analogy is also included. The hybrid method has
been assessed in an open-cavity flow at a Mach number of 0.85 and a Reynolds number of
Re=1.36×106, where some experimental data are available for comparison. The study has
identified some important technical issues in the application of the FW-H acoustic analogy
to cavity noise prediction and CAA in general, including the proper selection of the
integration period and the modes of sound sources in the frequency domain. The different
nature of 2D and 3D wave propagation is also highlighted, which calls for a matching
acoustic solver for each problem. The developed hybrid method has shown promise to be a
feasible, accurate and computationally affordable approach for CAA
Design optimisation of a slotless brushless permanent magnet DC motor with helically-wound laminations for underwater rim-driven thrusters
Full text linkRim (or tip) driven thrusters with structurally integrated brushless PM motors are now an established technology with an increasing range of applications. In these thrusters, the stator of the motor is housed within the thruster duct, and the rotor forms a ring around the tips of the propeller. Such high pole number motors tend to be very thin radially, have very small axial length to diameter ratios, and have relatively large airgaps to accommodate corrosion protection layers on the surfaces of the rotor and stator. The relatively large diameter stator laminations of such machines tend, therefore, to have a very thin back of core and narrow teeth, which make them expensive and difficult to manufacture. This thesis proposes an alternative motor topology featuring a toothless stator whose laminations are manufactured from a single strip of steel that is edge wound into a spiral.The electromagnetic design of the motor was optimised for maximum efficiency for a given propeller torque and speed. The airgap flux density in was obtained from an analytical solution of Laplace and Poisson's equations of scalar magnetic potential. Electromagnetic torque was calculated for ideal square wave current distribution. Copper and core losses were estimated in the usual manner. Design of the machine was refined using transient finite element analysis, allowing for rotation of the rotor. The design optimisation revealed that there is an optimum radial thickness for the permanent magnet and number of poles at which the efficiency is maximum. A demonstrator machine was built and tested, and yield a 10% lower efficiency when compared with an existing slotted machine of the same diameter, with an increased volume in the slotless machine of 15%. A cost analysis yielded that the slotless edge-wound laminations are cheaper to manufacture than slotted laser-cut laminations, however the costs of the increased magnet material required are higher. This project has demonstrated a potential cost savings in the manufacture of laminations, however, for this specific thruster application the costs are offset by the need for more magnet material
Will biological agents supplant systemic glucocorticoids as the first-line treatment for thyroid-associated ophthalmopathy?
No full textIn this article, the two authors present their opposing points of view concerning the likelihood that glucocorticoids will be replaced by newly developed biological agents in the treatment of active, moderate-to-severe thyroid-associated ophthalmopathy (TAO). TAO is a vexing, disfiguring and potentially blinding autoimmune manifestation of thyroid autoimmunity. One author expresses the opinion that steroids are nonspecific, frequently fail to improve the disease and can cause sometimes serious side effects. He suggests that glucocorticoids should be replaced as soon as possible by more specific and safer drugs, once they become available. The most promising of these are biological agents. The other author argues that glucocorticoids are proven effective and are unlikely to be replaced by biologicals. He reasons that while they may not uniformly result in optimal benefit, they have been proven effective in many reports. He remains open minded about alternative therapies such as biologicals but remains skeptical that they will replace steroids as the first-line therapy for active, moderate-to-severe TAO without head-to-head comparative clinical trials demonstrating superiority. Despite these very different points of view, both authors are optimistic about the availability of improved medical therapies for TAO, either as single agents or in combination. Further, both agree that better treatment options are needed to improve the care of our patients with active moderate-to-severe TAO
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