501 research outputs found

    Electronic structure of RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu) studied by angle-resolved photoemission spectroscopy

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    We use high resolution angle-resolved photoemission spectroscopy (ARPES) and electronic structure calculations to study the electronic properties of rare-earth monoantimonides RSb (R = Y, Ce, Gd, Dy, Ho, Tm, Lu). The experimentally measured Fermi surface (FS) of RSb consists of at least two concentric hole pockets at the Γ\Gamma point and two intersecting electron pockets at the XX point. These data agree relatively well with the electronic structure calculations. Detailed photon energy dependence measurements using both synchrotron and laser ARPES systems indicate that there is at least one Fermi surface sheet with strong three-dimensionality centered at the Γ\Gamma point. Due to the "lanthanide contraction", the unit cell of different rare-earth monoantimonides shrinks when changing rare-earth ion from CeSb to LuSb. This results in the differences in the chemical potentials in these compounds, which is demonstrated by both ARPES measurements and electronic structure calculations. Interestingly, in CeSb, the intersecting electron pockets at the XX point seem to be touching the valence bands, forming a four-fold degenerate Dirac-like feature. On the other hand, the remaining rare-earth monoantimonides show significant gaps between the upper and lower bands at the XX point. Furthermore, similar to the previously reported results of LaBi, a Dirac-like structure was observed at the Γ\Gamma point in YSb, CeSb, and GdSb, compounds showing relatively high magnetoresistance. This Dirac-like structure may contribute to the unusually large magnetoresistance in these compounds.Comment: 8 figure

    Regulation of Inhibitors of Differentiation Family Proteins by Thyroid-Stimulating Hormone in FRTL-5 Thyroid Cells

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    Members of the inhibitors of differentiation (Id) family of helix-loop-helix (HLH) proteins are known to play important roles in the proliferation and differentiation of many cell types. Thyroid-stimulating hormone (TSH) regulates proliferation and differentiation by activating TSH receptor (TSHR) in thyrocytes. In this study, we found that Id2, one of the Id family proteins, is a major target for regulation by TSH in FRTL-5 thyroid cells. TSH rapidly increases the Id2 mRNA level in FRTL-5 thyroid cells but the Id2 protein showed biphasic regulatory patterns, being transiently reduced and subsequently induced by TSH treatment. Transient reduction of Id2 protein was noted within 2 hr of TSH treatment and was mediated by proteasomal degradation. Moreover, reduced Id2 expression correlated with the activity of the phosphatidylinositol 3 kinase pathway, which is activated by TSH. Although TSH increases the activity of the Id2 promoter, TSH-induced activation of this promoter was independent of c-Myc. Id2 did not alter TTF-1- and Pax-8-mediated effects on the regulation of the Tg promoter. Thus, in summary, we found that TSH regulates Id2 expression, but that Id2 does not alter the expression of thyroid-specific genes, such as Tg, in FRTL-5 thyroid cells

    Measuring the total infrared light from galaxy clusters at z=0.5-1.6: connecting stellar populations to dusty star formation

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    Massive galaxy clusters undergo strong evolution from z~1.6 to z~0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far-infrared (IR) spectrum can directly trace this transformation; however, such studies have largely been limited to the massive galaxy end of cluster populations. In this work, we present ``total light" stacking techniques spanning 3.4-500{\mu}m aimed at revealing the total cluster IR emission, including low mass members and potential intracluster dust. We detail our procedures for WISE, Spitzer, and Herschel imaging, including corrections to recover the total stacked emission in the case of high fractions of detected galaxies. We apply our stacking techniques to 232 well-studied massive (log M200/Msun~13.8) clusters across multiple z bins, recovering extended cluster emission at all wavelengths, typically at >5sigma. We measure the averaged near- to far-IR radial profiles and SEDs, quantifying the total stellar and dust content. The near-IR radial profiles are well described by an NFW model with a high (c~7) concentration parameter. Dust emission is similarly concentrated, albeit suppressed at small radii (r<0.2Mpc). The measured SEDs lack warm dust, consistent with the colder SEDs expected for low mass galaxies. We derive total stellar masses consistent with the theoretical Mhalo-M_star relation and specific-star formation rates that evolve strongly with redshift, echoing that of massive (log Mstar/Msun>10) cluster galaxies. Separating out the massive galaxy population reveals that the majority of cluster far-IR emission (~70-80%) is provided by the low mass constituents, which differs from field galaxies. This effect may be a combination of mass-dependent quenching and excess dust in low mass cluster galaxies.Comment: 32 pages, 16 figures, 7 tables. Submitted to MNRAS, comments welcome

    A Comprehensive Analysis of Fermi Gamma-ray Burst Data: III. Energy-Dependent T90 Distributions of GBM GRBs and Instrumental Selection Effect on Duration Classification

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    The durations (T90) of 315 GRBs detected with Fermi/GBM (8-1000 keV) by 2011 September are calculated using the Bayesian Block method. We compare the T90 distributions between this sample and those derived from previous/current GRB missions. We show that the T90 distribution of this GRB sample is bimodal, with a statistical significance level being comparable to those derived from the BeppoSAX/GRBM sample and the Swift/BAT sample, but lower than that derived from the CGRO/BATSE sample. The short-to-long GRB number ratio is also much lower than that derived from the BATSE sample, i.e., 1:6.5 vs 1:3. We measure T90 in several bands, i.e., 8-15, 15-25, 25-50, 50-100, 100-350, and 350-1000 keV, to investigate the energy-dependence effect of the bimodal T90 distribution. It is found that the bimodal feature is well observed in the 50-100 and 100-350 keV bands, but is only marginally acceptable in the 25-50 keV and 350-1000 keV bands. The hypothesis of the bimodality is confidently rejected in the 8-15 and 15-25 keV bands. The T90 distributions in these bands are roughly consistent with those observed by missions with similar energy bands. The parameter T90 as a function of energy follows \bar T90 \propto E^{-0.20\pm 0.02} for long GRBs. Considering the erratic X-ray and optical flares, the duration of a burst would be even much longer for most GRBs. Our results, together with the observed extended emission of some short GRBs, indicate that the central engine activity time scale would be much longer than T90} for both long and short GRBs and the observed bimodal T90 distribution may be due to an instrumental selection effect.Comment: 29 pages, 2 tables, 9 figures, accepted for publication in Ap

    Dynamic structural health monitoring of slender structures using optical sensors

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    In this paper we summarize the research activities at the Instituto de TelecomunicaçÔes—PĂłlo de Aveiro and University of Aveiro, in the field of fiber Bragg grating based sensors and their applications in dynamic measurements for Structural Health Monitoring of slender structures such as towers. In this work we describe the implementation of an optical biaxial accelerometer based on fiber Bragg gratings inscribed on optical fibers. The proof-of-concept was done with the dynamic monitoring of a reinforced concrete structure and a slender metallic telecommunication tower. Those structures were found to be suitable to demonstrate the feasibility of FBG accelerometers to obtain the structures’ natural frequencies, which are the key parameters in Structural Health Monitoring and in the calibration of numerical models used to simulate the structure behavior

    Low-Temperature Preparation of Superparamagnetic CoFe2O4 Microspheres with High Saturation Magnetization

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    Based on a low-temperature route, monodispersed CoFe2O4 microspheres (MSs) were fabricated through aggregation of primary nanoparticles. The microstructural and magnetic characteristics of the as-prepared MSs were characterized by X-ray diffraction/photoelectron spectroscopy, scanning/transmitting electron microscopy, and vibrating sample magnetometer. The results indicate that the diameters of CoFe2O4 MSs with narrow size distribution can be tuned from over 200 to ~330 nm. Magnetic measurements reveal these MSs exhibit superparamagnetic behavior at room temperature with high saturation magnetization. Furthermore, the mechanism of formation of the monodispersed CoFe2O4 MSs was discussed on the basis of time-dependent experiments, in which hydrophilic PVP plays a crucial role

    Osteocalcin, vascular calcification, and atherosclerosis: a systematic review and meta-analysis

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    Background: Osteocalcin (OC) is an intriguing hormone, concomitantly being the most abundant non-collagenous peptide found in the mineralized matrix of bone, and expanding the endocrine function of the skeleton with far reaching extra-osseous effects. A new line of enquiry between OC and vascular calcification has emerged in response to observations that the mechanism of vascular calcification resembles that of bone mineralisation. To date, studies have reported mixed results. This systematic review and meta-analysis aimed to identify any association between OC and vascular calcification and atherosclerosis. Methods and results: Databases were searched for original, peer reviewed human studies. A total of 1,453 articles were retrieved, of which 46 met the eligibility criteria. Overall 26 positive, 17 negative, and 29 neutral relationships were reported for assessments between OC (either concentration in blood, presence of OC-positive cells, or histological staining for OC) and extent of calcification or atherosclerosis. Studies that measured OC-positive cells or histological staining for OC reported positive relationships (11 studies). A higher percentage of Asian studies found a negative relationship (36%) in contrast to European studies (6%). Studies examining carboxylated and undercarboxylated forms of OC in the blood failed to report consistent results. The meta-analysis found no significant difference between OC concentration in the blood between patients with “atherosclerosis” and control (p = 0.13, n = 1,197). Conclusion: No definitive association was determined between OC and vascular calcification or atherosclerosis; however, the presence of OC-positive cells and histological staining had a consistent positive correlation with calcification or atherosclerosis. The review highlighted several themes, which may influence OC within differing populations leading to inconclusive results. Large, longitudinal studies are required to further current understanding of the clinical relevance of OC in vascular calcification and atherosclerosis

    Truly form-factor–free industrially scalable system integration for electronic textile architectures with multifunctional fiber devices

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    Funding Information: This work was supported by the European Commission (H2020, 1D-NEON, grant agreement ID: 685758). J.M.K. and L.G.O. acknowledge the support from the U.K. Research and Innovation (EPSRC, EP/P027628/1). We thank Y. Bernstein and J. Faulkner for helping with grammar check. Funding Information: Acknowledgments Funding:ThisworkwassupportedbytheEuropeanCommission(H2020,1D-NEON,grant agreementID:685758).J.M.K.andL.G.O.acknowledgethesupportfromtheU.K.Researchand Innovation(EPSRC,EP/P027628/1).W ethankY .BernsteinandJ.Faulknerforhelpingwith grammarcheck.Authorcontributions:S.L.andJ.M.K.conceivedtheproject.S.L.,L.G.O.,P .B., R.Martins,andJ.M.K.supervisedtheproject.S.L.andH.L.developedF-PD.S.L.,Y .-W .L., G.-H.A., D.-W .S., J.I.S.,andS.C.developedF-SC.C.L.F ., A.S.,R.I.,P .B., andR.Martinsdevelopedfiber transistor.S.L.,H.L.,andS.C.developedF-LED.ThefiberdeviceswereevaluatedbyS.L.,H.W .C., D.-W .S., H.L.,S.J.,S.D.H.,S.Y .B., S.Z.,W .H.-C., Y .-H.S., X.-B.F ., T .H.L., J.-W .J., andY .K. The developmentofweavingprocesswasconductedbyS.L.,H.W .C., F .M.M., P .J., andV .G.C. Thelaser interconnectionwasdevelopedbyS.L.,H.W .C., K.U.,M.E.,andM.S.Thetextiledemonstrations werecharacterizedbyS.L.,H.W .C., D.-W .S., J.Y ., S.S.,U.E.,S.N.,A.C.,A.M.,R.MomentÚ,J.G.,N.D., S.M.,C.-H.K.,M.L.,A.N.,D.J.,M.C.,andY .C. ThismanuscriptwaswrittenbyS.L.andJ.M.K.and reviewed by H.W .C., D.-W .S., M.C.,L.G.O., P .B., E.F ., and G.A.J.A. All authors discussed the results andcommentedonthemanuscript.Competinginterests:Theauthorsdeclarethattheyhave nocompetinginterests.Dataandmaterialsavailability:Alldataneededtoevaluatethe conclusionsinthepaperarepresentinthepaperand/ortheSupplementaryMaterials. Publisher Copyright: Copyright © 2023 The Authors, some rights reserved.An integrated textile electronic system is reported here, enabling a truly free form factor system via textile manufacturing integration of fiber-based electronic components. Intelligent and smart systems require freedom of form factor, unrestricted design, and unlimited scale. Initial attempts to develop conductive fibers and textile electronics failed to achieve reliable integration and performance required for industrial-scale manufacturing of technical textiles by standard weaving technologies. Here, we present a textile electronic system with functional one-dimensional devices, including fiber photodetectors (as an input device), fiber supercapacitors (as an energy storage device), fiber field-effect transistors (as an electronic driving device), and fiber quantum dot light-emitting diodes (as an output device). As a proof of concept applicable to smart homes, a textile electronic system composed of multiple functional fiber components is demonstrated, enabling luminance modulation and letter indication depending on sunlight intensity.publishersversionpublishe
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