1,982 research outputs found

    The chemokine receptor CCR8 is preferentially expressed in Th2 but not Th1 cells

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    In this paper we report on the cloning and characterization of mouse CCR8. Like its human homologue, it is predominantly expressed in the thymus. In the periphery, murine CCR8 mRNA was found most abundantly expressed in activated Th2-polarized cells and in NK1.1+ CD4+ T cells. Human CCR8 is also preferentially expressed in human Th2-polarized cells and clones. This pattern of expression suggests that CCR8 is part of a Th2-specific gene expression program. The CCR8 ligands I-309 and its mouse homologue T cell activation gene 3 (TCA-3) are potent chemoattractants for Th2-polarized cells. Taken together, these observations strongly suggest that CCR8 plays a role in the control of Th2 responses, and may represent a potential target for treatment of allergic diseases

    North Atlantic mid-latitude surface-circulation changes through the Plio-Pleistocene intensification of northern hemisphere glaciation

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    This is the final version. Available from American Geophysical Union (AGU) / Wiley via the DOI in this record.All new data presented are available at https://doi.pangaea.de/10.1594/PANGAEA.892805The North Atlantic Current (NAC) transports warm salty water to high northern latitudes, with important repercussions for ocean circulation and global climate. A southward displacement of the NAC and Subarctic Front, which separate subpolar and subtropical water masses, is widely suggested for the last glacial maximum (LGM) and may have acted as a positive feedback in glacial expansion at this time. However, the role of the NAC during the intensification of northern hemisphere glaciation (iNHG) ~3.5 to 2.5 Ma, is less clear. Here, we present new records from IODP Site U1313 (41°N) spanning ~2.8-2.4 Ma to trace the influence of Subarctic Front waters above this mid-latitude site. We reconstruct surface and permanent pycnocline temperatures and seawater δ18O using paired Mg/Ca-δ18O measurements on the planktic foraminifers Globigerinoides ruber and Globorotalia crassaformis, and determine abundances of the subpolar foraminifer Neogloboquadrina atlantica. We find that the first significant glacial incursions of Subarctic Front surface waters above Site U1313 did not occur until ~2.6 Ma. At no time during our study interval was (sub)surface reorganisation in the mid-latitude North Atlantic analogous to the LGM. Our findings suggest that LGM-like processes sensu stricto cannot be invoked to explain interglacial-glacial cycle amplification during iNHG. They also imply that increased glacial productivity at Site U1313 during iNHG was not only driven by southward deflections of the Subarctic Front. We suggest nutrient injection from cold-core eddies and enhanced glacial dust delivery may have played additional roles in increasing export productivity in the mid-latitude North Atlantic from 2.7 Ma.Funding for this research was provided by IODP France (CTB) and the German Research Foundation (DFG) (grant OF 2544/2 to OF). IB is grateful to the UK IODP for financial support for shipboard and post-cruise participation in IODP Exp. 306. CTB, KT, TDG, LV, CS, and ME acknowledge OSU Pythéas. MMR acknowledges support by the USGS Land Change Science Program. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government. PAW acknowledges NERC UK IODP NE/F00141X/1 and a Royal Society Wolfson Merit Award

    Composite Dirac Neutrinos

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    We present a mechanism that naturally produces light Dirac neutrinos. The basic idea is that the right-handed neutrinos are composite. Any realistic composite model must involve `hidden flavor' chiral symmetries. In general some of these symmetries may survive confinement, and in particular, one of them manifests itself at low energy as an exact BLB-L symmetry. Dirac neutrinos are therefore produced. The neutrinos are naturally light due to compositeness. In general, sterile states are present in the model, some of them can naturally be warm dark matter candidates.Comment: 12 pages; Sec. IIC updated; minor corrections; published versio

    Frequency of apnea, bradycardia, and desaturations following first diphtheria-tetanus-pertussis-inactivated polio-Haemophilus influenzae type B immunization in hospitalized preterm infants

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    BACKGROUND: Adverse cardiorespiratory events including apnea, bradycardia, and desaturations have been described following administration of the first diphtheria-tetanus-pertussis-inactivated polio-Haemophilus influenzae type B (DTP-IPV-Hib) immunization to preterm infants. The effect of the recent substitution of acellular pertussis vaccine for whole cell pertussis vaccine on the frequency of these events requires further study. METHODS: Infants with gestational age of ≤ 32 weeks who received their first DTP-IPV-Hib immunization prior to discharge from two Edmonton Neonatal Intensive Care Units January 1, 1996 to November 30, 2000 were eligible for the study. Each immunized infant was matched by gestational age to one control infant. The number of episodes of apnea, bradycardia, and/or desaturations (ABD) and the treatment required for these episodes in the 72 hours prior to and 72 hours post-immunization (for the immunized cohort) or at the same post-natal age (for controls) was recorded. RESULTS: Thirty-four infants who received DTP-IPV-Hib with whole cell pertussis vaccine, 90 infants who received DTP-IPV-Hib with acellular pertussis vaccine, and 124 control infants were entered in the study. Fifty-six immunized infants (45.1%) and 36 control infants (29.0%) had a resurgence of or increased ABD in the 72 hours post-immunization in the immunized infants and at the same post-natal age in the controls with an adjusted odds ratio for immunized infants of 2.41 (95% CI 1.29,4.51) as compared to control infants. The incidence of an increase in adverse cardiorespiratory events post-immunization was the same in infants receiving whole cell or acellular pertussis vaccine (44.1% versus 45.6%). Eighteen immunized infants (14.5%) and 51 control infants (41.1%) had a reduction in ABD in the 72 hours post- immunization or at the equivalent postnatal age in controls for an odds ratio of 0.175 (95%CI 0.08, 0.39). The need for therapy of ABD in the immunized infants was not statistically different from the control infants. Lower weight at the time of immunization was a risk factor for a resurgence of or increased ABD post-immunization. Birth weight, gestational age, postnatal age or sex were not risk factors. CONCLUSION: There is an increase in adverse cardiorespiratory events following the first dose of DTP-IPV-Hib in preterm infants. Lower current weight was identified as a risk factor, with the risk being equivalent for whole cell versus acellular pertussis vaccine. Although most of these events are of limited clinical significance, cardiorespiratory monitoring of infants who are sufficiently preterm that they are receiving their first immunization prior to hospital discharge should be considered for 72 hours post-immunization

    Surface and Temporal Biosignatures

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    Recent discoveries of potentially habitable exoplanets have ignited the prospect of spectroscopic investigations of exoplanet surfaces and atmospheres for signs of life. This chapter provides an overview of potential surface and temporal exoplanet biosignatures, reviewing Earth analogues and proposed applications based on observations and models. The vegetation red-edge (VRE) remains the most well-studied surface biosignature. Extensions of the VRE, spectral "edges" produced in part by photosynthetic or nonphotosynthetic pigments, may likewise present potential evidence of life. Polarization signatures have the capacity to discriminate between biotic and abiotic "edge" features in the face of false positives from band-gap generating material. Temporal biosignatures -- modulations in measurable quantities such as gas abundances (e.g., CO2), surface features, or emission of light (e.g., fluorescence, bioluminescence) that can be directly linked to the actions of a biosphere -- are in general less well studied than surface or gaseous biosignatures. However, remote observations of Earth's biosphere nonetheless provide proofs of concept for these techniques and are reviewed here. Surface and temporal biosignatures provide complementary information to gaseous biosignatures, and while likely more challenging to observe, would contribute information inaccessible from study of the time-averaged atmospheric composition alone.Comment: 26 pages, 9 figures, review to appear in Handbook of Exoplanets. Fixed figure conversion error

    Fundamental Concepts

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    This chapter briefly discusses the fundamental properties of black holes in general relativity, the discovery of astrophysical black holes and their main astronomical observations, how X-ray and γ\gamma-ray facilities can study these objects, and ends with a list of open problems and future developments in the field.Comment: 14 pages, 4 figures. To appear in "Tutorial Guide to X-ray and Gamma-ray Astronomy: Data Reduction and Analysis" (Ed. C. Bambi, Springer Singapore, 2020). v2: fixed some typos and updated some parts. arXiv admin note: text overlap with arXiv:1711.1025
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