64,210 research outputs found

    Localisation of the melanocortin-2-receptor and its accessory proteins in the developing and adult adrenal gland

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    The melanocortin-2-receptor (MC2R)/MC2R accessory protein (MRAP) complex is critical to the production of glucocorticoids from the adrenal cortex. Inactivating mutations in either MC2R or MRAP result in the clinical condition familial glucocorticoid deficiency. The localisation of MC2R together with MRAP within the adrenal gland has not previously been reported. Furthermore, MRAP2, a paralogue of MRAP, has been shown in vitro to have a similar function to MRAP, facilitating MC2R trafficking and responsiveness to ACTH. Despite similar MC2R accessory functions, in vivo, patients with inactivating mutations of MRAP fail to be rescued by a functioning MRAP2 gene, suggesting differences in adrenal expression, localisation and/or function between the two MRAPs. In this study on the rat adrenal gland, we demonstrate that while MRAP and MC2R are highly expressed in the zona fasciculata, MRAP2 is expressed throughout the adrenal cortex in low quantities. In the developing adrenal gland, both MRAP and MRAP2 are equally well expressed. The MC2R/MRAP2 complex requires much higher concentrations of ACTH to activate compared with the MC2R/MRAP complex. Interestingly, expression of MC2R and MRAP in the undifferentiated zone would support the notion that ACTH may play an important role in adrenal cell differentiation and maintenance

    1^{1}H-NMR spin-echo measurements of the static and dynamic spin properties in λ\lambda-(BETS)2_{2}FeCl4_{4}

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    1^{1}H-NMR spin-echo measurements of the spin-echo decay M(2τ)M(2\tau) with a decay rate 1/T2T_{2} and the frequency shift Δν/ν0\Delta\nu/\nu_{0} under applied magnetic field B\mathbf{B}0_{0} = 9 T along the a-axis over a temperature range 2.0−-180 K are reported for a single crystal of the organic conductor λ\lambda-(BETS)2_{2}FeCl4_{4}. It provides the spin dynamic and static properties in the paramagnetic metal (PM) and antiferromagnetic insulator (AFI) states as well as across the PM−-AFI phase transition. A large slow beat structure in the spin-echo decay is observed with a typical beat frequency of ff ∼\sim 7 kHz and it varies across the spectrum. Its origin is attributed to the 1^{1}H−-1^{1}H dipole interactions rather than to the much larger dipolar field contribution from the Fe3+^{3+} electrons (spin SS = 5/2). A simple phenomenological model provides an excellent fit to the data. The dominant 1^{1}H-NMR frequency shift comes from the dipolar field from the 3d Fe3+^{3+} ions, and the Fe3+^{3+} −- Fe3+^{3+} exchange interactions (J0J_{0}) (J0J_{0} includes the d−-d exchange interactions through the π−\pi-electrons) have a substantial effect to the local field at the proton sites expecially at low temperatures. A good fit is obtained with J0J_{0} = - 1.7 K. The data of the spin-echo decay rate 1/T2T_{2} indicates that there is a significant change in the slow fluctuations of the local magnetic field at the 1^{1}H-sites on traversing the PM to AFI phase. This evidence supports earlier reports that the PM−-AFI phase transition in λ\lambda-(BETS)2_{2}% FeCl4_{4} is driven magnetically and first order.Comment: 9 pages, 10 figures, resubmitted to Phys. Rev. B in response to comments of Editor and reviewers on March 23, 200

    ICT as learning media and research instrument: What eResearch can offer for those who research eLearning?

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    Students‘ interactions in digital learning environments are distributed over time and space, and many aspects of eLearning phenomenon cannot be investigated using traditional research approaches. At the same time, the possibility to collect digital data about students‘ online interactions and learning opens a range of new opportunities to use ICT as research tool and apply new research approaches. This symposium brings together some of the recent advancements in the area of ICT-enhanced research and aims to discuss future directions for methodological innovation in this area. The session will include four presentations that will explore different directions of ICT use for eLearning research

    Investigation of the effects of inlet shapes on fan noise radiation

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    The effect of inlet shape on forward radiated fan tone noise directivities was investigated under experimentally simplified zero flow conditions. Simulated fan tone noise was radiated to the far field through various shaped zero flow inlets. Baseline data were collected for the simplest baffled and unbaffled straight pipe inlets. These data compared well with prediction. The more general inlet shapes tested were the conical, circular, and exponential surfaces of revolution and an asymmetric inlet achieved by cutting a straight pipe inlet at an acute angle. Approximate theories were developed for these general shapes and some comparisons with data are presented. The conical and exponential shapes produced directivities that differed considerably from the baseline data while the circular shape produced directivities similar to the baseline data. The asymmetric inlet produced asymmetric directivities with significant reductions over the straight pipe data for some angles

    Operational benefits from the terminal configured vehicle

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    The NASA Terminal Configured Vehicle is a flying laboratory used to conduct research and development on improved airborne systems (including avionics) and operational flight procedures, with particular emphasis on utilization in the terminal area environment. The objectives of this technology development activity, focused on conventional transport aircraft, are to develop and demonstrate improvements which can lead to increased airport and runway capacity, increased air traffic controller productivity, energy efficient terminal area operations, reduced weather minima with safety, and reduced community noise by use of appropriate procedures. This paper discusses some early results of this activity in addition to defining present efforts and future research plans

    Description and catalog of ionospheric F-region data, Jicamarca Radar Observatory, November 1966 - April 1969

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    Equatorial ionospheric F-region data reduced from the Jicamarca Radar Observatory (JRO) incoherent scatter observations for particular periods is described. It lists in catalog form the times of the observations made during those periods. These F-region data include the electron concentration and the electron and ion temperatures. The data were inferred from the incoherent scatter observations of JRO

    Decay of a superfluid current of ultra-cold atoms in a toroidal trap

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    Using a numerical implementation of the truncated Wigner approximation, we simulate the experiment reported by Ramanathan et al. in Phys. Rev. Lett. 106, 130401 (2011), in which a Bose-Einstein condensate is created in a toroidal trap and set into rotation via a phase imprinting technique. A potential barrier is then placed in the trap to study the decay of the superflow. We find that the current decays via thermally activated phase slips, which can also be visualized as vortices crossing the barrier region in the radial direction. Adopting the notion of critical velocity used in the experiment, we determine it to be lower than the local speed of sound at the barrier, in contradiction to the predictions of the zero-temperature Gross-Pitaevskii equation. We map out the superfluid decay rate and critical velocity as a function of temperature and observe a strong dependence. Thermal fluctuations offer a partial explanation of the experimentally observed reduction of the critical velocity from the phonon velocity.Comment: 15 pages. 11 figure
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