247 research outputs found
Magnetic order and disorder in nanomagnets probed by superconducting vortices
We have studied two nanomagnet systems with strong (Co/Pd multilayers) and
weak (NdCo alloy films) stray magnetic fields by probing the out-of-plane
magnetic states with superconducting vortices. The hybrid samples are made of
array of nanomagnets embedded in superconducting Nb thin films. The vortex
motion detects relevant magnetic state features, since superconducting vortices
are able to discriminate between different magnetic stray field strengths and
directions. The usual matching effect between the superconducting vortex
lattice and the periodic pinning array can be quenched by means of disorder
magnetic potentials with strong stray fields at random. Ordered stray fields
retrieve the matching effect and yield asymmetry and shift in the vortex
dissipation signal. Furthermore vortices can discriminate the sizes of the
nanomagnet magnetic domains, detecting magnetic domain sizes as small as 70 nm.
In addition, we observe that the vortex cores play the crucial role instead of
the supercurrents around the vortex.Comment: 22 pages, 8 figure
Native American ancestry significantly contributes to neuromyelitis optica susceptibility in the admixed Mexican population
Neuromyelitis Optica (NMO) is an autoimmune disease with a higher prevalence in non-European populations. Because the Mexican population resulted from the admixture between mainly Native American and European populations, we used genome-wide microarray, HLA high-resolution typing and AQP4 gene sequencing data to analyze genetic ancestry and to seek genetic variants conferring NMO susceptibility in admixed Mexican patients. A total of 164 Mexican NMO patients and 1,208 controls were included. On average, NMO patients had a higher proportion of Native American ancestry than controls (68.1% vs 58.6%; p = 5 Ă 10â6). GWAS identified a HLA region associated with NMO, led by rs9272219 (OR = 2.48, P = 8 Ă 10â10). Class II HLA alleles HLA-DQB1*03:01, -DRB1*08:02, -DRB1*16:02, -DRB1*14:06 and -DQB1*04:02 showed the most significant associations with NMO risk. Local ancestry estimates suggest that all the NMO-associated alleles within the HLA region are of Native American origin. No novel or missense variants in the AQP4 gene were found in Mexican patients with NMO or multiple sclerosis. To our knowledge, this is the first study supporting the notion that Native American ancestry significantly contributes to NMO susceptibility in an admixed population, and is consistent with differences in NMO epidemiology in Mexico and Latin America.Fil: Romero Hidalgo, Sandra. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Flores Rivera, JosĂ©. Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xicoFil: Rivas Alonso, VerĂłnica. Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xicoFil: Barquera, Rodrigo. Max Planck Institute For The Science Of Human History; Alemania. Instituto Nacional de AntropologĂa e Historia; MĂ©xicoFil: Villarreal Molina, MarĂa Teresa. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Antuna Puente, BĂĄrbara. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Macias Kauffer, Luis Rodrigo. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Villalobos ComparĂĄn, Marisela. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Ortiz Maldonado, Jair. Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xicoFil: Yu, Neng. American Red Cross; Estados UnidosFil: Lebedeva, Tatiana V.. American Red Cross; Estados UnidosFil: Alosco, Sharon M.. American Red Cross; Estados UnidosFil: GarcĂa RodrĂguez, Juan Daniel. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: GonzĂĄlez Torres, Carolina. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Rosas Madrigal, Sandra. Instituto Nacional de Medicina GenĂłmica; MĂ©xicoFil: Ordoñez, Graciela. NeuroimmunologĂa, Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xicoFil: Guerrero Camacho, Jorge Luis. Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xicoFil: Treviño Frenk, Irene. American British Cowdray Medical Center; MĂ©xico. Instituto Nacional de la NutriciĂłn Salvador Zubiran; MĂ©xicoFil: Escamilla Tilch, Monica. Instituto Nacional de la NutriciĂłn Salvador Zubiran; MĂ©xicoFil: GarcĂa Lechuga, Maricela. Instituto Nacional de la NutriciĂłn Salvador Zubiran; MĂ©xicoFil: Tovar MĂ©ndez, VĂctor Hugo. Instituto Nacional de la NutriciĂłn Salvador Zubiran; MĂ©xicoFil: Pacheco Ubaldo, Hanna. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: Acuña Alonzo, Victor. Instituto Nacional de AntropologĂa E Historia. Escuela Nacional de AntropologĂa E Historia; MĂ©xicoFil: Bortolini, MarĂa CĂĄtira. Universidade Federal do Rio Grande do Sul; BrasilFil: Gallo, Carla. Universidad Peruana Cayetano Heredia; PerĂșFil: Bedoya BerrĂo, Gabriel. Universidad de Antioquia; ColombiaFil: Rothhammer, Francisco. Universidad de TarapacĂĄ; ChileFil: Gonzalez-Jose, Rolando. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro CientĂfico TecnolĂłgico Conicet - Centro Nacional PatagĂłnico. Instituto PatagĂłnico de Ciencias Sociales y Humanas; ArgentinaFil: Ruiz Linares, AndrĂ©s. Colegio Universitario de Londres; Reino UnidoFil: Canizales Quinteros, Samuel. Universidad Nacional AutĂłnoma de MĂ©xico; MĂ©xicoFil: Yunis, Edmond. Dana Farber Cancer Institute; Estados UnidosFil: Granados, Julio. Instituto Nacional de la NutriciĂłn Salvador Zubiran; MĂ©xicoFil: Corona, Teresa. Instituto Nacional de NeurologĂa y NeurocirugĂa; MĂ©xic
The QUIJOTE experiment: project status and first scientific results
We present the current status of the QUIJOTE (Q-U-I JOint TEnerife) experiment, a new polarimeter with the aim of characterizing the polarization of the Cosmic Microwave Background, and other galactic or extra-galactic physical processes that emit in microwaves in the frequency range 10â42 GHz, and at large angular scales (around 1 degree resolution). The experiment has been designed to reach the required sensitivity to detect a primordial gravitational wave component in the CMB, provided its tensor-to-scalar ratio is larger than r ⌠0.05. The project consists of two telescopes and three instruments which will survey a large sky area from the Teide Observatory to provide I, Q and U maps of high sensitivity. The first QUIJOTE instrument, known as Multi-Frequency Instrument (MFI), has been surveying the northern sky in four individual frequencies between 10 and 20 GHz since November 2012, providing data with an average sensitivity of 80 ”K beamâ1 in Q and U in a region of 20, 000 square-degrees. The second instrument, or Thirty-GHz Instrument (TGI), is currently undergoing the commissioning phase, and the third instrument, or Forty-GHz Instrument (FGI), is in the final fabrication phase. Finally, we describe the first scientific results obtained with the MFI. Some specific regions, mainly along the Galactic plane, have been surveyed to a deeper depth, reaching sensitivities of around 40 ”K beamâ1. We present new upper limits on the polarization of the anomalous dust emission, resulting from these data, in the Perseus molecular complex and in the W43 molecular complex
Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications
Superparamagnetic iron oxide nanoparticles
can providemultiple benefits for biomedical applications
in aqueous environments such asmagnetic separation or
magnetic resonance imaging. To increase the colloidal
stability and allow subsequent reactions, the introduction
of hydrophilic functional groups onto the particlesâ
surface is essential. During this process, the original
coating is exchanged by preferably covalently bonded
ligands such as trialkoxysilanes. The duration of the
silane exchange reaction, which commonly takes more
than 24 h, is an important drawback for this approach. In
this paper, we present a novel method, which introduces
ultrasonication as an energy source to dramatically
accelerate this process, resulting in high-quality waterdispersible nanoparticles around 10 nmin size. To prove
the generic character, different functional groups were
introduced on the surface including polyethylene glycol
chains, carboxylic acid, amine, and thiol groups. Their
colloidal stability in various aqueous buffer solutions as
well as human plasma and serum was investigated to
allow implementation in biomedical and sensing
applications.status: publishe
Planck 2018 results: IX. Constraints on primordial non-Gaussianity
We analyse the Planck full-mission cosmic microwave background (CMB) temperature and E-mode polarization maps to obtain constraints on primordial non-Gaussianity (NG). We compare estimates obtained from separable template-fitting, binned, and optimal modal bispectrum estimators, finding consistent values for the local, equilateral, and orthogonal bispectrum amplitudes. Our combined temperature and polarization analysis produces the following final results: flocalNL= -0.9 \ub1 5.1; fequilNL= -26 \ub1 47; and forthoNL= -38 \ub1 24 (68% CL, statistical). These results include low-multipole (4 64 \u2113 < 40) polarization data that are not included in our previous analysis. The results also pass an extensive battery of tests (with additional tests regarding foreground residuals compared to 2015), and they are stable with respect to our 2015 measurements (with small fluctuations, at the level of a fraction of a standard deviation, which is consistent with changes in data processing). Polarizationonly bispectra display a significant improvement in robustness; they can now be used independently to set primordial NG constraints with a sensitivity comparable to WMAP temperature-based results and they give excellent agreement. In addition to the analysis of the standard local, equilateral, and orthogonal bispectrum shapes, we consider a large number of additional cases, such as scale-dependent feature and resonance bispectra, isocurvature primordial NG, and parity-breaking models, where we also place tight constraints but do not detect any signal. The nonprimordial lensing bispectrum is, however, detected with an improved significance compared to 2015, excluding the null hypothesis at 3.5\u3c3. Beyond estimates of individual shape amplitudes, we also present model-independent reconstructions and analyses of the Planck CMB bispectrum. Our final constraint on the local primordial trispectrum shape is glocalNL= (-5.8 \ub1 6.5)
7 104(68% CL, statistical), while constraints for other trispectrum shapes are also determined. Exploiting the tight limits on various bispectrum and trispectrum shapes, we constrain the parameter space of different early-Universe scenarios that generate primordial NG, including general single-field models of inflation, multi-field models (e.g. curvaton models), models of inflation with axion fields producing parity-violation bispectra in the tensor sector, and inflationary models involving vector-like fields with directionally-dependent bispectra. Our results provide a high-precision test for structure-formation scenarios, showing complete agreement with the basic picture of the CDM cosmology regarding the statistics of the initial conditions, with cosmic structures arising from adiabatic, passive, Gaussian, and primordial seed perturbations
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