On the rôle of rotations and Bogoliubov transformations in neutrino mixing

We show that mixing transformations for Dirac fields arise as a consequence of the non-trivial interplay between rotations and Bogoliubov transformations at level of ladder operators. Indeed the non-commutativity between the algebraic generators of such transformations turns out to be responsible of the unitary inequivalence of the flavor and mass representations and of the associated vacuum structure. A possible thermodynamic interpretation is also investigated

Electronic temperatures of terahertz quantum cascade active regions with phonon scattering assisted injection and extraction scheme

We measured the lattice and subband electronic temperatures of terahertz quantum cascade devices based on the optical phonon-scattering assisted active region scheme. While the electronic temperature of the injector state (j=4) significantly increases by \u25b3T=Te 4 -TL 3c40 K, in analogy with the reported values in resonant phonon scheme (\u25b3T 3c70-110 K), both the laser levels (j=2,3) remain much colder with respect to the latter (by a factor of 3-5) and share the same electronic temperature of the ground level (j=1). The electronic population ratio n2/n1 shows that the optical phonon scattering efficiently depopulates the lower laser level (j=2) up to an electronic temperature Te 3c180 K. \ua9 2013 Optical Society of America.Peer reviewed: YesNRC publication: Ye

FOXN1 mutation abrogates prenatal T-cell development in humans

Background The transcription factor FOXN1 is implicated in the differentiation of thymic and skin epithelial cells, and alterations in it are responsible for the Nude/SCID phenotype. During a genetic counselling programme offered to couples at risk in a community where a high frequency of mutated FOXN1 had been documented, the identification of a human FOXN1(-/-) fetus gave the unique opportunity to study T cell development in utero. Results Total blockage of CD4(+) T cell maturation and severe impairment of CD8(+) cells were documented. Evaluation of the variable-domain beta-chain (V beta) families' usage among T lymphocytes revealed that the generation of T cell receptor (TCR) diversity occurred to some extent in the FOXN1(-/-) fetus, although it was impaired compared with the control. A few non-functional CD8(+) cells, mostly bearing TCR gamma delta in the absence of CD3, were found. Discussion FOXN1 is crucial for in utero T cell development in humans. The identification of a limited number of CD8(+) cells suggests an extrathymic origin for these cells, implying FOXN1-independent lymphopoiesis

Molecular evidence for a thymus-independent partial T cell development in a FOXN1-/- athymic human fetus

The thymus is the primary organ able to support T cell ontogeny, abrogated in FOXN1(-/-) human athymia. Although evidence indicates that in animal models T lymphocytes may differentiate at extrathymic sites, whether this process is really thymus-independent has still to be clarified. In an athymic FOXN1(-/-) fetus, in which we previously described a total blockage of CD4(+) and partial blockage of CD8(+) cell development, we investigated whether intestine could play a role as extrathymic site of T-lymphopoiesis in humans. We document the presence of few extrathymically developed T lymphocytes and the presence in the intestine of CD3(+) and CD8(+), but not of CD4(+) cells, a few of them exhibiting a CD45RA(+) naïve phenotype. The expression of CD3εεpTα, RAG1 and RAG2 transcripts in the intestine and TCR gene rearrangement was also documented, thus indicating that in humans the partial T cell ontogeny occurring at extrathymic sites is a thymus- and FOXN1-independent process