Nearly Mass-Degenerate Majorana Neutrinos: Double Beta Decay and Neutrino Oscillations

Assuming equal tree-level Majorana masses for the standard-model neutrinos, either from the canonical seesaw mechanism or from a heavy scalar triplet, I discuss how their radiative splitting may be relevant to neutrinoless double beta decay and neutrino oscillations.Comment: 12 pages, including 4 figures, talk at NANP9

Experimental and bond graph based sensitivity calculations for micro-scale robust engineering design

Copyright @ 2005 IEEEBond graph modeling and sensitivity analysis are used to provide a platform for the robust design of a small mechatronic device, a behind-the-ear (BTE) hearing aid. Two key components of the device, namely the telecoil and the receiver, are considered. Experimental measurements, bond graph simulation models and analytic sensitivity analysis are used to investigate the interaction between these components in order to gain insight into the effect of component placement on the robustness of the final product

Structure and texture of the quark mass matrix

Starting from a weak basis in which the up (or down) quark matrix is diagonal, we obtain an exact set of equations for the quark mass matrix elements in terms of known observables. We make a numerical analysis of the down (up) quark mass matrix. Using the data available for the quark masses and mixing angles at different energy scales, we found a numerical expression for these matrices. We suggest that it is not possible to have an specific texture from this analysis. We also examine the most general case when the complex phases are introduced in the mass matrix. We find the numerical value for these phases as a function of $\delta$, the CP-violationg phase.Comment: 7 pages, we use the macros of Elsevie

Explicit towers of Drinfeld modular curves

We give explicit equations for the simplest towers of Drinfeld modular curves over any finite field, and observe that they coincide with the asymptotically optimal towers of curves constructed by Garcia and Stichtenoth.Comment: 10 pages. For mini-symposium on "curves over finite fields and codes" at the 3rd European Congress in Barcelona 7/2000 Revised to correct minor typographical and grammatical error

A_4 Symmetry and Lepton Masses and Mixing

Stimulated by Ma's idea which explains the tribimaximal neutrino mixing by assuming an A_4 flavor symmetry, a lepton mass matrix model is investigated. A Frogatt-Nielsen type model is assumed, and the flavor structures of the masses and mixing are caused by the VEVs of SU(2)_L-singlet scalars \phi_i^u and \phi_i^d (i=1,2,3), which are assigned to {\bf 3} and ({\bf 1}, {\bf 1}',{\bf 1}'') of A_4, respectively.Comment: 13 pages including 1 table, errors in Sec.7 correcte

Neutrino Exotica in the Skew E_6 Left-Right Model

With the particle content of the 27 representation of E_6, a skew left-right supersymmetric gauge model was proposed many years ago, with a variety of interesting phenomenological implications. The neutrino sector of this model offers a natural framework for obtaining small Majorana masses for nu_e, nu_mu, and nu_tau, with the added bonus of accommodating 2 light sterile neutrinos.Comment: 12 pages, no figure, conclusion clarifie

Genetic variation in genes interacting with BRCA1/2 and risk of breast cancer in Cypriot population.

Inability to correctly repair DNA damage is known to play a role in the development of breast cancer. Single nucleotide polymorphisms (SNPs) of DNA repair genes have been identified, which modify the DNA repair capacity, which in turn may affect the risk of developing breast cancer. To assess whether alterations in DNA repair genes contribute to breast cancer, we genotyped 62 SNPs in 29 genes in 1,109 Cypriot women with breast cancer and 1,177 age-matched healthy controls. Five SNPs were associated with breast cancer. SNPs rs13312840 and rs769416 in the NBS1 gene were associated with a decrease in breast cancer risk (OR TT vs. TC/CC = 0.58; 95% CI, 0.37-0.92; P = 0.019 and OR GG vs. GT/TT = 0.23, 95% CI 0.06-0.85, P = 0.017, respectively). The variant allele of MRE11A rs556477 was also associated with a reduced risk of developing the disease (OR AA vs. AG/GG = 0.76; 95% CI, 0.64-0.91; P = 0.0022). MUS81 rs545500 and PBOV1 rs6927706 SNPs were associated with an increased risk of developing breast cancer (OR GG vs. GC/CC = 1.21, 95% CI, 1.02-1.45; P = 0.031; OR AA vs. AG/GG = 1.53, 95% CI, 1.07-2.18; P = 0.019, respectively). Finally, haplotype-based tests identified significant associations between specific haplotypes in MRE11A and NBS1 genes and breast cancer risk. Further large-scale studies are needed to confirm these results

Scalar Mass Bounds in Two Supersymmetric Extended Electroweak Gauge Models

In two recently proposed supersymmetric extended electroweak gauge models, the reduced Higgs sector at the 100-GeV energy scale consists of only two doublets, but they have quartic scalar couplings different from those of the minimal supersymmetric standard model. In the SU(2) X SU(2) X U(1) model, there is an absolute upper bound of about 145 GeV on the mass of the lightest neutral scalar boson. In the SU(3) X U(1) model, there is only a parameter-dependent upper bound which formally goes to infinity in a particular limitComment: 9 pages (6 figures not included), UCRHEP-T128 (July 1994

Thermal effects on lattice strain in hcp Fe under pressure

We compute the c/a lattice strain versus temperature for nonmagnetic hcp iron at high pressures using both first-principles linear response quasiharmonic calculations based on the full potential linear-muffin-tin-orbital (LMTO) method and the particle-in-cell (PIC) model for the vibrational partition function using a tight-binding total-energy method. The tight-binding model shows excellent agreement with the all-electron LMTO method. When hcp structure is stable, the calculated geometric mean frequency and Helmholtz free energy of hcp Fe from PIC and linear response lattice dynamics agree very well, as does the axial ratio as a function of temperature and pressure. On-site anharmonicity proves to be small up to the melting temperature, and PIC gives a good estimate of its sign and magnitude. At low pressures, hcp Fe becomes dynamically unstable at large c/a ratios, and the PIC model might fail where the structure approaches lattice instability. The PIC approximation describes well the vibrational behavior away from the instability, and thus is a reasonable approach to compute high temperature properties of materials. Our results show significant differences from earlier PIC studies, which gave much larger axial ratio increases with increasing temperature, or reported large differences between PIC and lattice dynamics results.Comment: 9 figure

Heat flow method to Lichnerowicz type equation on closed manifolds

In this paper, we establish existence results for positive solutions to the Lichnerowicz equation of the following type in closed manifolds -\Delta u=A(x)u^{-p}-B(x)u^{q},\quad in\quad M, where $p>1, q>0$, and $A(x)>0$, $B(x)\geq0$ are given smooth functions. Our analysis is based on the global existence of positive solutions to the following heat equation {ll} u_t-\Delta u=A(x)u^{-p}-B(x)u^{q},\quad in\quad M\times\mathbb{R}^{+}, u(x,0)=u_0,\quad in\quad M with the positive smooth initial data $u_0$.Comment: 10 page