Anomalous TEM Modes in Guiding Structures Filled With Double Negative and Double Positive Materials

2007 ◽  
Vol 17 (1) ◽  
pp. 19-21 ◽  
Author(s):  
Giovanni Bozza ◽  
Giacomo Oliveri ◽  
Mirco Raffetto
Keyword(s):  
Double Negative ◽  
Double Positive ◽  
Positive Materials

scholarly journals Properties of the Band Gaps in 1D Ternary Lossy Photonic Crystal Containing Double-Negative Materials

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Alireza Aghajamali ◽  
Maryam Akbarimoosavi ◽  
Mahmood Barati
Keyword(s):  
Incidence Angle ◽  
Band Gaps ◽  
Angle Of Incidence ◽  
Double Negative ◽  
Double Positive ◽  
One Dimensional ◽  
Binary Structure ◽  
Negative Materials ◽  
The One ◽  
Positive Materials

Theoretically, the characteristics matrix method is employed to investigate and compare the properties of the band gaps of the one-dimensional ternary and binary lossy photonic crystals which are composed of double-negative and double-positive materials. This study shows that by varying the angle of incidence, the band gaps for TM and TE waves behave differently in both ternary and binary lossy structures. The results demonstrate that, by increasing the angle of incidence for the TE wave, the width and the depth of zero-n¯, zero-μ, and Bragg gap increase in both ternary and binary structures. On the other hand, the enhancement of the angle of incidence for the TM wave contributes to reduction of the width and the depth of the zero-n¯ and Bragg gaps, and they finally disappear for incidence angles greater than 50° and 60° for the binary structure and 40° and 45° for the ternary structures, respectively. In addition, the details of the edges of the band gaps variations as a function of incidence angle for both structures are studied.

scholarly journals Critical and Multiple Roles for the CD3ε Intracytoplasmic Tail in Double Negative to Double Positive Thymocyte Differentiation

2009 ◽  
Vol 182 (8) ◽  
pp. 4844-4853 ◽  
Author(s):  
Jean-Francois Brodeur ◽  
Samantha Li ◽  
Maria da Silva Martins ◽  
Louise Larose ◽  
Vibhuti P. Dave
Keyword(s):  
Multiple Roles ◽  
Double Negative ◽  
Double Positive ◽  
Double Positive Thymocyte ◽  
Thymocyte Differentiation

Pre-TCR signaling regulates IL-7 receptor α expression promoting thymocyte survival at the transition from the double-negative to double-positive stage

2003 ◽  
Vol 33 (7) ◽  
pp. 1968-1977 ◽  
Author(s):  
Cesar Trigueros ◽  
Katsuto Hozumi ◽  
Bruno Silva-Santos ◽  
Ludovica Bruno ◽  
Adrian C. Hayday ◽  
...  
Keyword(s):  
Double Negative ◽  
Tcr Signaling ◽  
Double Positive

scholarly journals Distinct contracted conformations of the Tcra/Tcrd locus during Tcra and Tcrd recombination

2010 ◽  
Vol 207 (9) ◽  
pp. 1835-1841 ◽  
Author(s):  
Han-Yu Shih ◽  
Michael S. Krangel
Keyword(s):  
In Situ Hybridization ◽  
Fluorescence In Situ Hybridization ◽  
Three Dimensional ◽  
Double Negative ◽  
Thymocyte Development ◽  
Double Positive ◽  
Long Distance ◽  
Large Pool ◽  
Antigen Receptor Loci

Studies have suggested that antigen receptor loci adopt contracted conformations to promote long-distance interactions between gene segments during V(D)J recombination. The Tcra/Tcrd locus is unique because it undergoes highly divergent Tcrd and Tcra recombination programs in CD4−CD8− double negative (DN) and CD4+CD8+ double positive (DP) thymocytes, respectively. Using three-dimensional fluorescence in situ hybridization, we asked whether these divergent recombination programs are supported by distinct conformational states of the Tcra/Tcrd locus. We found that the 3′ portion of the locus is contracted in DN and DP thymocytes but not in B cells. Remarkably, the 5′ portion of the locus is contracted in DN thymocytes but is decontracted in DP thymocytes. We propose that the fully contracted conformation in DN thymocytes allows Tcrd rearrangements involving Vδ gene segments distributed over 1 Mb, whereas the unique 3′-contracted, 5′-decontracted conformation in DP thymocytes biases initial Tcra rearrangements to the most 3′ of the available Vα gene segments. This would maintain a large pool of distal 5′ Vα gene segments for subsequent rounds of recombination. Thus, distinct contracted conformations of the Tcra/Tcrd locus may facilitate a transition from a Tcrd to a Tcra mode of recombination during thymocyte development.

scholarly journals Defined αβ T Cell Receptors with Distinct Ligand Specificities Do Not Require Those Ligands to Signal Double Negative Thymocyte Differentiation

2004 ◽  
Vol 199 (12) ◽  
pp. 1719-1724 ◽  
Author(s):  
Batu Erman ◽  
Terry I. Guinter ◽  
Alfred Singer
Keyword(s):  
T Cell ◽  
T Cell Development ◽  
Cell Receptor ◽  
Peptide Ligands ◽  
Double Negative ◽  
Antigen Receptors ◽  
Double Positive ◽  
Recombination Activating Gene ◽  
Thymocyte Differentiation ◽  
Deficient Mice

During T cell development in the thymus, pre–T cell receptor (TCR) complexes signal CD4− CD8− (double negative [DN]) thymocytes to differentiate into CD4+ CD8+ (double positive [DP]) thymocytes, and they generate such signals without apparent ligand engagements. Although ligand-independent signaling is unusual and might be unique to the pre-TCR, it is possible that other TCR complexes such as αβ TCR or αγ TCR might also be able to signal the DN to DP transition in the absence of ligand engagement if they were expressed on DN thymocytes. Although αγ TCR complexes efficiently signal DN thymocyte differentiation, it is not yet certain if αβ TCR complexes are also capable of signaling DN thymocyte differentiation, nor is it certain if such signaling is dependent upon ligand engagement. This study has addressed these questions by expressing defined αβ TCR transgenes in recombination activating gene 2−/− pre-Tα−/− double deficient mice. In such double deficient mice, the only antigen receptors that can be expressed are those encoded by the αβ TCR transgenes. In this way, this study definitively demonstrates that αβ TCR can in fact signal the DN to DP transition. In addition, this study demonstrates that transgenic αβ TCRs signal the DN to DP transition even in the absence of their specific MHC–peptide ligands.

A novel single step double positive double negative selection strategy for β-globin gene replacement

2006 ◽  
Vol 345 (1) ◽  
pp. 14-20 ◽  
Author(s):  
H. Khanahmad ◽  
M.R. Noori Daloii ◽  
M.A. Shokrgozar ◽  
K. Azadmanesh ◽  
A.R. Niavarani ◽  
...  
Keyword(s):  
Negative Selection ◽  
Globin Gene ◽  
Gene Replacement ◽  
Single Step ◽  
Selection Strategy ◽  
Double Negative ◽  
Double Positive
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