5,420 research outputs found
Superfluid state of repulsively interacting three-component fermionic atoms in optical lattices
We investigate the superfluid state of repulsively interacting
three-component (color) fermionic atoms in optical lattices. When the
anisotropy of the three repulsive interactions is strong, atoms of two of the
three colors form Cooper pairs and atoms of the third color remain a Fermi
liquid. An effective attractive interaction is induced by density fluctuations
of the third-color atoms. This superfluid state is stable against changes in
filling close to half filling. We determine the phase diagrams in terms of
temperature, filling, and the anisotropy of the repulsive interactions.Comment: 5 pages, 6 figure
Activation volumes in CoPtCr-SiO2 perpendicular recording media
CoPtCr-SiO2 perpendicular recording media with varying levels of SiO2 were examined by two different methods to determine the activation volume. The first is based on the sweep-rate dependence of the remanence coercivity using Sharrock's equation. The second is based on the measurement of the fluctuation field from time-dependence data, determined using a magneto-optical Kerr effect (MOKE) magnetometer. The values of V-act measured at the coercivity for both methods are almost the same, with the fluctuation field and activation volumes increasing with the SiO2 content. The difference between V-act and the grain volume measured directly from bright-field TEM images decreases as the SiO2 content increases due to the reduction of intergranular exchange coupling. The experimental results indicate that values of V-act obtained from single- and double-layered media are consistent. It was also found that the coercivity and normalized hysteresis loop slope at coercivity varied with SiO2 content, with the coercivity peaking at 8 at % SiO2 (nearly 26 vol% SiO2)
The tissue distribution of the B7-2 costimulator in mice: abundant expression on dendritic cells in situ and during maturation in vitro
Inaba, K., Witmer-Pack, M., Inaba, M., Sakuta, H., Hathcock, K.S., Azuma, M., Yagita, H., Okumura, K., Linsley, P.S., Ikehara, S., Muramatsu, S., Hodes, R.J., and Steinman, R.M. The tissue distribution of the B7-2 costimulator in mice: abundant expression on dendritic cells in situ and during maturation in vitro. J. Exp. Med. 180: 1849-1860, 1994https://digitalcommons.rockefeller.edu/historical-scientific-reports/1037/thumbnail.jp
The function of Ia+ dendritic cells and ia dendritic cell precursors in thymocyte mitogenesis to lectin and lectin plus interleukin i
[No abstract available
The Tissue Distribution of the B7-2 Costimulator in Mice: Abundant Expression on Dendritic Cells In Situ and During Maturation In Vitro
B7-2 is a recently discovered, second ligand for the CTLA-4/CD28, T cell signaling system. Using the GL-1 rat monoclonal antibody (mAb), we monitored expression of B7-2 on mouse leukocytes with an emphasis on dendritic cells. By cytofluorography, little or no B7-2 was detected on most cell types isolated from spleen, thymus, peritoneal cavity, skin, marrow, and blood. However, expression of B7-2 could be upregulated in culture. In the case of epidermal and spleen dendritic cells, which become highly immunostimulatory for T cells during a short period of culture, the upregulation of B7-2 was dramatic and did not require added stimuli. Lipopolysaccharide did not upregulate B7-2 levels on dendritic cells, in contrast to macrophages and B cells. By indirect immunolabeling, the level of staining with GL-1 mAb exceeded that seen with rat mAbs to several other surface molecules including intercellular adhesion molecule 1, B7-1, CD44, and CD45, as well as new hamster mAbs to CD40, CD48, and B7-1/CD80. Of these accessory molecules, B7-2 was a major species that increased in culture, implying a key role for B7-2 in the functional maturation of dendritic cells. B7-2 was the main (\u3e90%) CTLA-4 ligand on mouse dendritic cells. When we applied GL-1 to tissue sections of a dozen different organs, clear-cut staining with B7-2 antigen was found in many. B7-2 staining was noted on liver Kupffer cells, interstitial cells of heart and lung, and profiles in the submucosa of the esophagus. B7-2 staining was minimal in the kidney and in the nonlymphoid regions of the gut, and was not observed at all in the brain. In the tongue, only rare dendritic cells in the oral epithelium were B7-2 +, but reactive cells were scattered about the interstitial spaces of the muscle. In all lymphoid tissues, GI-1 strongly stained certain distinct regions that are occupied by dendritic cells and by macrophages. For dendritic cells, these include the thvmic medulla, splenic periarterial sheaths, and lymph node deep cortex; for macrophages, the B7-2-rich regions included the splenic marginal zone and lymph node subcapsular cortex. Splenic B7-2+ cells were accessible to labeling with GL-1 mAb given intravenously. Dendritic cell stimulation of T cells (DNA synthesis) during the mixed leukocyte reaction was significantly (35-65%) blocked by GL-1. The block could be enhanced by adding 1G10 anti-B7-1 or by using CTLA-4 Ig, a ligand for both B7-1 and B7-2. We conclude that B7-2, like other accessory molecules, is expressed by many types of antigen-presenting cells. However, the regulation and extent of B7-2 expression seems to differ among cell types. Dendritic cells express very high levels, in several sites in vivo and after maturation into strong accessory cells in culture
High levels of a major histocompatibility complex II-self peptide complex on dendritic cells from the T cell areas of lymph nodes
T lymphocytes recirculate continually through the T cell areas of peripheral lymph nodes. During each passage, the T cells survey the surface of large dendritic cells (DCs), also known as interdigitating cells. However, these DCs have been difficult to release from the lymph node. By emphasizing the use of calcium-free media, as shown by Vremec et al. (Vremec, D., M. Zorbas, R. Scollay, D. J. Saunders, C.F. Ardavin, L. Wu, and K. Shortman. 1992. J. Exp. Med. 176:47-58.), we have been able to release and enrich DCs from the T cell areas. The DCs express the CD11c leukocyte integrin, the DEC- 205 multilectin receptor for antigen presentation, the intracellular granule antigens which are recognized by monoclonal antibodies M342, 2A1, and MIDC- 8, very high levels of MHC I and MHC II, and abundant accessory molecules such as CD40, CD54, and CD86. When examined with the Y-Ae monoclonal which recognizes complexes formed between I-A(b) and a peptide derived from I-Eα, the T cell area DCs expressed the highest levels. The enriched DCs also stimulated a T-T hybridoma specific for this MHC II-peptide complex, and the hybridoma underwent apoptosis. Therefore DCs within the T cell areas can be isolated. Because they present very high levels of self peptides, these DCs should be considered in the regulation of self reactivity in the periphery
Immunologic properties of purified epidermal langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes
[No abstract available
Immunologic properties of purified epidermal Langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes
Inaba, K., Schuler, G., Witmer, M., Valinsky, J., Atassi, B., and Steinman, R.M. Immunologic properties of purified epidermal Langerhans cells: Distinct requirements for stimulation of unprimed and sensitized T lymphocytes. J. Exp. Med. 164: 605-613, 1986.https://digitalcommons.rockefeller.edu/historical-scientific-reports/1019/thumbnail.jp
Clustering of dendritic cells, helper T lymphocytes, and histocompatible B cells during primary antibody responses in vitro
[No abstract available
Identification of proliferating dendritic cell precursors in mouse blood
While it has been known that dendritic cells arise from proliferating precursors in situ, it has been difficult to identify progenitors in culture. We find that aggregates of growing dendritic cells develop in cultures of mouse blood that are supplemented with granulocyte/macrophage colony-stimulating factor (GM-CSF) but not other CSFs. The dendritic cell precursor derives from the Ia-negative and nonadherent fraction. The aggregates of developing dendritic cells appear at about 1 wk of culture, with 100 or more such clusters being formed per 106 blood leukocytes. The aggregates can be dislodged and subcultured as expanding clusters that are covered with cells having the motile sheet-like processes (“veils”) of dendritic cells. By about 2 wk, large numbers of single, major histocompatibility complex (MHC) class II-rich dendritic cells begin to be released into the medium. Combined immunoperoxidase and [3H]thymidine autoradiograph, show that the cells that proliferate within the aggregate lack certain antigenic markers that are found on mature dendritic cells. However, in pulse-chase protocols, the [3H]thymidinelabeled progeny exhibit many typical dendritic cell features, including abundant MHC class II and a cytoplasmic granular antigen identified by monodonal antibody 2A1. The progeny dendritic cells are potent stimulators of the mixed leukocyte reaction and can home to the T-dependent areas of lymph node after injection into the footpads. We conclude that mouse blood contains GM-CSF-dependent, proliferating progenitors that give rise to large numbers of dendritic cells with characteristic morphology, mobility, phenotype, and strong T cell stimulatory function
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