Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 ...with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.
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In addition to a bulk energy gap, topological insulators accommodate a conducting, linearly dispersed Dirac surface state. This state is predicted to become massive if time reversal symmetry is ...broken, and to become insulating if the Fermi energy is positioned inside both the surface and bulk gaps. We introduced magnetic dopants into the three-dimensional topological insulator dibismuth triselenide (Bi₂Se₃) to break the time reversal symmetry and further position the Fermi energy inside the gaps by simultaneous magnetic and charge doping. The resulting insulating massive Dirac fermion state, which we observed by angle-resolved photoemission, paves the way for studying a range of topological phenomena relevant to both condensed matter and particle physics.
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Establishing the appropriate theoretical framework for unconventional superconductivity in the iron-based materials requires correct understanding of both the electron correlation strength and the ...role of Fermi surfaces. This fundamental issue becomes especially relevant with the discovery of the iron chalcogenide superconductors. Here, we use angle-resolved photoemission spectroscopy to measure three representative iron chalcogenides, FeTe0.56Se0.44, monolayer FeSe grown on SrTiO3 and K0.76Fe1.72Se2. We show that these superconductors are all strongly correlated, with an orbital-selective strong renormalization in the dxy bands despite having drastically different Fermi surface topologies. Furthermore, raising temperature brings all three compounds from a metallic state to a phase where the dxy orbital loses all spectral weight while other orbitals remain itinerant. These observations establish that iron chalcogenides display universal orbital-selective strong correlations that are insensitive to the Fermi surface topology, and are close to an orbital-selective Mott phase, hence placing strong constraints for theoretical understanding of iron-based superconductors.
The recent discovery of superconductivity in the iron oxypnictide family of compounds has generated intense interest. The layered crystal structure with transition-metal ions in planar square-lattice ...form and the discovery of spin-density-wave order near 130 K (refs 10, 11) seem to hint at a strong similarity with the copper oxide superconductors. An important current issue is the nature of the ground state of the parent compounds. Two distinct classes of theories, distinguished by the underlying band structure, have been put forward: a local-moment antiferromagnetic ground state in the strong-coupling approach, and an itinerant ground state in the weak-coupling approach. The first approach stresses on-site correlations, proximity to a Mott-insulating state and, thus, the resemblance to the high-transition-temperature copper oxides, whereas the second approach emphasizes the itinerant-electron physics and the interplay between the competing ferromagnetic and antiferromagnetic fluctuations. The debate over the two approaches is partly due to the lack of conclusive experimental information on the electronic structures. Here we report angle-resolved photoemission spectroscopy (ARPES) of LaOFeP (superconducting transition temperature, Tc = 5.9 K), the first-reported iron-based superconductor. Our results favour the itinerant ground state, albeit with band renormalization. In addition, our data reveal important differences between these and copper-based superconductors.
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DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
Bacterial flagellin, a Toll‐like receptor 5 agonist, is used as an adjuvant for immunomodulation. In this study, we aimed to evaluate the effect and its mechanism following intralymphatic ...administration of OVA‐flagellin (FlaB) mixture in the mouse model of allergic rhinitis.
Materials and Methods
BALB/c mice were sensitized with OVA and treated with an OVA‐FlaB mixture via intranasal, sublingual, and intralymphatic routes to evaluate the effect of each treatment. Several parameters for allergic inflammation and its underlying mechanisms were then evaluated.
Results
Intralymphatic injection of the OVA‐FlaB mixture reduced symptom scores, eosinophil infiltration in the nasal mucosa, and total and OVA‐specific IgE levels more significantly than intranasal and sublingual administration. Systemic cytokine (IL‐4, IL‐5, IL‐6, IL‐17, and IFN‐γ) production and local cytokine (IL‐4 and IL‐5) production were also reduced significantly after intralymphatic injection with OVA‐FlaB. Double intralymphatic injection of the mixture was more effective than single injection. Moreover, the expression of innate cytokines such as IL‐25 and IL‐33 in nasal epithelial cells was reduced, and the expression of chemokines such as CCL24 (eotaxin‐2), CXCL1, and CXCL2 was decreased in the nasal mucosa, suggesting the underlying mechanism for intralymphatic administration of the OVA‐FlaB mixture.
Conclusion
Intralymphatic administration of an OVA‐FlaB mixture was more effective in alleviating allergic inflammation than intranasal and sublingual administration in a mouse model of allergic rhinitis. This effect may be attributed to the reduced expression of innate cytokines and chemokines. This treatment modality can be considered as a new therapeutic method and agent.
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According to the current paradigm, galaxies initially form as disc galaxies at the centres of their own dark matter haloes. During their subsequent evolution, they may undergo a transformation to a ...red, early-type galaxy, thus giving rise to the build-up of the red sequence. Two important, outstanding questions are (i) which transformation mechanisms are most important and (ii) in what environment do they occur. In this paper, we study the impact of transformation mechanisms that operate only on satellite galaxies, such as strangulation, ram-pressure stripping and galaxy harassment. Using a large galaxy group catalogue constructed from the Sloan Digital Sky Survey, we compare the colours and concentrations of satellites galaxies to those of central galaxies of the same stellar mass, adopting the hypothesis that the latter are the progenitors of the former. On average, satellite galaxies are redder and more concentrated than central galaxies of the same stellar mass, indicating that satellite-specific transformation processes do indeed operate. Central-satellite pairs that are matched in both stellar mass and colour, however, show no average concentration difference, indicating that the transformation mechanisms operating on satellites affect colour more than morphology. We also find that the colour and concentration differences of matched central-satellite pairs are completely independent of the mass of the host halo (not to be confused with the subhalo) of the satellite galaxy, indicating that satellite-specific transformation mechanisms are equally efficient in host haloes of all masses. This strongly rules against mechanisms that are thought to operate only in very massive haloes, such as ram-pressure stripping or harassment. Instead, we argue that strangulation is the main transformation mechanism for satellite galaxies. Finally, we determine the relative importance of satellite quenching for the build-up of the red sequence. We find that roughly 70 per cent of red-sequence satellite galaxies with M*∼ 109h−2M⊙ had their star formation quenched as satellites. This drops rapidly with increasing stellar mass, reaching virtually zero at M*∼ 1011h−2M⊙. Therefore, a very significant fraction of red satellite galaxies were already quenched before they became a satellite.
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We use a modified version of the halo-based group finder developed by Yang et al. to select galaxy groups from the Sloan Digital Sky Survey (SDSS DR4). In the first step, a combination of two methods ...is used to identify the centers of potential groups and to estimate their characteristic luminosity. Using an iterative approach, the adaptive group finder then uses the average mass-to-light ratios of groups, obtained from the previous iteration, to assign a tentative mass to each group. This mass is then used to estimate the size and velocity dispersion of the underlying halo that hosts the group, which in turn is used to determine group membership in redshift space. Finally, each individual group is assigned two different halo masses: one based on its characteristic luminosity and the other based on its characteristic stellar mass. Applying the group finder to the SDSS DR4, we obtain 301,237 groups in a broad dynamic range, including systems of isolated galaxies. We use detailed mock galaxy catalogs constructed for the SDSS DR4 to test the performance of our group finder in terms of completeness of true members, contamination by interlopers, and accuracy of the assigned masses. This paper is the first in a series and focuses on the selection procedure, tests of the reliability of the group finder, and the basic properties of the group catalog (e.g., the mass-to-light ratios, the halo mass-to-stellar mass ratios). The group catalogs including the membership of the groups are available on request.
We investigate various galaxy occupation statistics of dark matter halos using a large galaxy group catalog constructed from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) with an adaptive ...halo-based group finder. The conditional luminosity function (CLF) is measured separately for all, red, and blue galaxies, as well as in terms of central and satellite galaxies. The CLFs for central and satellite galaxies can be well modeled with a lognormal distribution and a modified Schechter form, respectively. About 85% of the central galaxies and about 80% of the satellite galaxies in halos with masses image are red galaxies. These numbers decrease to 50% and 40%, respectively, in halos with image. For halos of a given mass, the distribution of the luminosities of central galaxies, image, has a dispersion of about 0.15 dex. The mean luminosity (stellar mass) of the central galaxies scales with halo mass as image for halos with masses image, and both relations are significantly steeper for less massive halos. We also measure the luminosity and stellar mass gaps between the first and second brightest (most massive) member galaxies, image. These gap statistics, especially in halos with image, indicate that the luminosities of central galaxies are clearly distinct from those of their satellites. The fraction of fossil groups, defined as those groups with image, ranges from image2.5% for groups with image to 18%-60% for groups with image. Finally, we measure the fraction of satellites, which changes from image5.0% for galaxies with image to image40% for galaxies with image.
Despite scientific and clinical advances in the field of pharmacogenomics (PGx), application into routine care remains limited. Opportunely, several implementation studies and programs have been ...initiated over recent years. This article presents an overview of these studies and identifies current research gaps. Importantly, one such gap is the undetermined collective clinical utility of implementing a panel of PGx‐markers into routine care, because the evidence base is currently limited to specific, individual drug‐gene pairs. The Ubiquitous Pharmacogenomics (U‐PGx) Consortium, which has been funded by the European Commission's Horizon‐2020 program, aims to address this unmet need. In a prospective, block‐randomized, controlled clinical study (PREemptive Pharmacogenomic testing for prevention of Adverse drug REactions PREPARE), pre‐emptive genotyping of a panel of clinically relevant PGx‐markers, for which guidelines are available, will be implemented across healthcare institutions in seven European countries. The impact on patient outcomes and cost‐effectiveness will be investigated. The program is unique in its multicenter, multigene, multidrug, multi‐ethnic, and multihealthcare system approach.
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A large amount of observations have constrained cosmological parameters and the initial density fluctuation spectrum to a very high accuracy. However, cosmological parameters change with time and the ...power index of the power spectrum dramatically varies with mass scale in the so-called concordance Delta *LCDM cosmology. Thus, any successful model for its structural evolution should work well simultaneously for various cosmological models and different power spectra. We use a large set of high-resolution N-body simulations of a variety of structure formation models (scale-free, standard CDM, open CDM, and Delta *LCDM) to study the mass accretion histories, the mass and redshift dependence of concentrations, and the concentration evolution histories of dark matter halos. We find that there is significant disagreement between the much-used empirical models in the literature and our simulations. Based on our simulation results, we find that the mass accretion rate of a halo is tightly correlated with a simple function of its mass, the redshift, parameters of the cosmology, and of the initial density fluctuation spectrum, which correctly disentangles the effects of all these factors and halo environments. We also find that the concentration of a halo is strongly correlated with the universe age when its progenitor on the mass accretion history first reaches 4% of its current mass. According to these correlations, we develop new empirical models for both the mass accretion histories and the concentration evolution histories of dark matter halos, and the latter can also be used to predict the mass and redshift dependence of halo concentrations. These models are accurate and universal: the same set of model parameters works well for different cosmological models and for halos of different masses at different redshifts, and in the Delta *LCDM case the model predictions match the simulation results very well even though halo mass is traced to about 0.0005 times the final mass, when cosmological parameters and the power index of the initial density fluctuation spectrum have changed dramatically. Our model predictions also match the PINOCCHIO mass accretion histories very well, which are much independent of our numerical simulations and our definitions of halo merger trees. These models are also simple and easy to implement, making them very useful in modeling the growth and structure of dark matter halos. We provide appendices describing the step-by-step implementation of our models. A calculator which allows one to interactively generate data for any given cosmological model is provided on the Web, together with a user-friendly code to make the relevant calculations and some tables listing the expected concentration as a function of halo mass and redshift in several popular cosmological models. We explain why Delta *LCDM and open CDM halos on nearly all mass scales show two distinct phases in their mass growth histories. We discuss implications of the universal relations we find in connection to the formation of dark matter halos in the cosmic density field.
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