4,172 research outputs found

    Alignment of oblique rotators

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    Pulsars with torque aligning magnetic moment with spin axi

    What are the repercussions of disclosing a medical error?

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    Physicians and their staff may experience a resolution of anxiety and guilt that can improve their well-being (strength of recommendation [SOR]: C, based on survey data). Full disclosure has little effect, however, on the likelihood that an injured patient will seek legal counsel (SOR: C, based on survey data). Successful disclosure of a medical error can improve a patient's confidence in the physician and lead to improved outcomes (SOR: C, based on expert opinion)

    Improvement of the Embarrassingly Parallel Search for Data Centers

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    International audienceWe propose an adaptation of the Embarrassingly Parallel Search (EPS) method for data centers. EPS is a simple but efficient method for parallel solving of CSPs. EPS decomposes the problem in many distinct subproblems which are then solved independently by workers. EPS performed well on multi-cores machines (40), but some issues arise when using more cores in a datacenter. Here, we identify the decomposition as the cause of the degradation and propose a parallel decomposition to address this issue. Thanks to it, EPS gives almost linear speedup and outperforms work stealing by orders of magnitude using the Gecode solver

    Crust-core interactions and the magnetic dipole orientation in neutron stars

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    We develop an effective model for a neutron star with a magnetosphere. It takes into account the electromagnetic torques acting on the magnetic dipole, the friction forces between the crust and the core, and the gravitational corrections. Anomalous electromagnetic torques, usually neglected in a rigid star model, play here a crucial role for the alignement of the magnetic dipole. The crust-core coupling time implied by the model is consistent with the observational data and other theoretical estimations. This model describes the main features of the behavior of the magnetic dipole during the life of the star, and in particular gives a natural explanation for the n<3 value of the breaking index in a young neutron star.Comment: 23 pages, 1 figur

    Structural basis for HIV-1 gp120 recognition by a germ-line version of a broadly neutralizing antibody

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    Efforts to design an effective antibody-based vaccine against HIV-1 would benefit from understanding how germ-line B-cell receptors (BCRs) recognize the HIV-1 gp120/gp41 envelope spike. Potent VRC01-like (PVL) HIV-1 antibodies derived from the VH1-2*02 germ-line allele target the conserved CD4 binding site on gp120. A bottleneck for design of immunogens capable of eliciting PVL antibodies is that VH1-2*02 germ-line BCR interactions with gp120 are uncharacterized. Here, we report the structure of a VH1-2*02 germ-line antibody alone and a germ-line heavy-chain/mature light-chain chimeric antibody complexed with HIV-1 gp120. VH1-2*02 residues make extensive contacts with the gp120 outer domain, including all PVL signature and CD4 mimicry interactions, but not critical CDRH3 contacts with the gp120 inner domain and bridging sheet that are responsible for the improved potency of NIH45-46 over closely related clonal variants, such as VRC01. Our results provide insight into initial recognition of HIV-1 by VH1-2*02 germ-line BCRs and may facilitate the design of immunogens tailored to engage and stimulate broad and potent CD4 binding site antibodies

    The Effect of Cone Opsin Mutations on Retinal Structure and the Integrity of the Photoreceptor Mosaic

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    Purpose. To evaluate retinal structure and photoreceptor mosaic integrity in subjects with OPN1LW and OPN1MW mutations. Methods. Eleven subjects were recruited, eight of whom have been previously described. Cone and rod density was measured using images of the photoreceptor mosaic obtained from an adaptive optics scanning light ophthalmoscope (AOSLO). Total retinal thickness, inner retinal thickness, and outer nuclear layer plus Henle fiber layer (ONL+HFL) thickness were measured using cross-sectional spectral-domain optical coherence tomography (SD-OCT) images. Molecular genetic analyses were performed to characterize the OPN1LW/OPN1MW gene array. Results. While disruptions in retinal lamination and cone mosaic structure were observed in all subjects, genotype-specific differences were also observed. For example, subjects with “L/M interchange” mutations resulting from intermixing of ancestral OPN1LW and OPN1MW genes had significant residual cone structure in the parafovea (∼25% of normal), despite widespread retinal disruption that included a large foveal lesion and thinning of the parafoveal inner retina. These subjects also reported a later-onset, progressive loss of visual function. In contrast, subjects with the C203R missense mutation presented with congenital blue cone monochromacy, with retinal lamination defects being restricted to the ONL+HFL and the degree of residual cone structure (8% of normal) being consistent with that expected for the S-cone submosaic. Conclusions. The photoreceptor phenotype associated with OPN1LW and OPN1MW mutations is highly variable. These findings have implications for the potential restoration of visual function in subjects with opsin mutations. Our study highlights the importance of high-resolution phenotyping to characterize cellular structure in inherited retinal disease; such information will be critical for selecting patients most likely to respond to therapeutic intervention and for establishing a baseline for evaluating treatment efficacy

    Flow-Field Investigation of Gear-Flap Interaction on a Gulfstream Aircraft Model

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    Off-surface flow measurements of a high-fidelity 18% scale Gulfstream aircraft model in landing configuration with the main landing gear deployed are presented. Particle Image Velocimetry (PIV) and Laser Velocimetry (LV) were used to measure instantaneous velocities in the immediate vicinity of the main landing gear and its wake and near the inboard tip of the flap. These measurements were made during the third entry of a series of tests conducted in the NASA Langley Research Center (LaRC) 14- by 22-Foot Subsonic Tunnel (14 x 22) to obtain a comprehensive set of aeroacoustic measurements consisting of both aerodynamic and acoustic data. The majority of the off-body measurements were obtained at a freestream Mach number of 0.2, angle of attack of 3 degrees, and flap deflection angle of 39 degrees with the landing gear on. A limited amount of data was acquired with the landing gear off. LV was used to measure the velocity field in two planes upstream of the landing gear and to measure two velocity profiles in the landing gear wake. Stereo and 2-D PIV were used to measure the velocity field over a region extending from upstream of the landing gear to downstream of the flap trailing edge. Using a special traverse system installed under the tunnel floor, the velocity field was measured at 92 locations to obtain a comprehensive picture of the pertinent flow features and characteristics. The results clearly show distinct structures in the wake that can be associated with specific components on the landing gear and give insight into how the wake is entrained by the vortex at the inboard tip of the flap

    1620 GEOGRAPHOS AND 433 EROS: SHAPED BY PLANETARY TIDES?

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    Until recently, most asteroids were thought to be solid bodies whose shapes were determined largely by collisions with other asteroids. Recent work by Burns and others has shown that many asteroids may be little more than rubble piles, held together by self-gravity ; this means that their shapes may be strongly distorted by tides during close encounters with planets. Here we report on numerical simulations of encounters between an ellipsoid-shaped rubble-pile asteroid and Earth. After an encounter, many of the simulated asteroids develop the same rotation rate and distinctive shape as 1620 Geographos (i.e., highly elongated with a single convex side, tapered ends, and small protuberances swept back against the rotation direction). Since our numerical studies show that these events occur with some frequency, we suggest that Geographos may be a tidally distorted object. In addition, our work shows that 433 Eros, which will be visited by the NEAR spacecraft in 1999, is much like Geographos, suggesting that it too may have been molded by tides in the past
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