A Minimal See-Saw Model for Hierarchical Neutrino Masses with Large Mixing

The atmospheric and solar neutrino oscillation data suggest hierarchical neutrino masses with at least one large mixing. The simplest see-saw models for reconciling the two features are U(1) extensions of the SM with flavour dependent gauge charges. I discuss a minimal model of this type containing two heavy right-handed neutrinos, which have normal Dirac couplings to $\nu_\mu$ and $\nu_\tau$ but suppressed ones to $\nu_e$. It can naturally account for the large (small) mixing solutions to the atmospheric (solar) neutrino oscillation data.Comment: 6 pages, Latex, Invited Talk at the 6th San Miniato Topical Seminar on `Neutrino and Astroparticle Physics', to appear in Nuclear Physics B (Proc. Suppl.

The Strategic Impact of China\u27s Artificial Islands in the South China Sea and their Influence on U.S. and China Relations

This is an integrative literature review of various perspectives of different authors of previous scholarly articles discussing the impact of China’s artificial Islands in the South China Sea and how it affects U.S. China relations in the region. This research covers a range of parameters surrounding how the artificial islands were made and how they affect the overall security of naval operations and will also discuss international waterway rights within the South China Sea, one of the World’s biggest trading routes. A review of current events in the region is discussed highlighting the potential powder keg that could explode and how it can provide a starting point to summarize and identify the seriousness of the current fluid situation that is changing daily and how it potentially impacts the region. By conducting this integrative literature review the author aims to present a wholesome picture to educate the public about events that are shaping the region in the South China Sea. The results of this study will add clarity and awareness to the events in the region and how they impact the United States and China relations. The hope is that this research creates a dialogue that addresses the strategic impact these artificial islands are having on the United States and China relations in the region of the South China Sea

Terahertz quantum cascade laser with an X-valley-based injector

We present a novel terahertz (THz) quantum cascade laser (QCL) design where Γ-valley states are used for lasing transition and X-valley states—in particular, Xz-states—are used as injector subbands. Since the lasing states in our proposed structure are populated and depopulated mainly through the interface roughness assisted Γ-Xz electron scattering, we present a model to describe this intervalley carrier transport. In the injector region of the proposed THz QCL, we use quaternary AlGaAsP material to introduce tensile strain, which plays a crucial role in increasing the gain. To compensate the strain per period, we propose to grow the periodic heterostructure on a GaAs.94P.06 virtual substrate. To simulate the carrier transport, and hence calculate the gain and lasing performance of the proposed THz QCL, we use a simplified density matrix formalism that considers resonant tunneling, dephasing, and the important intersubband scattering mechanisms. Since electron temperature significantly varies from lattice temperature for QCLs, we take their difference into account using the kinetic energy balance (KEB) method. We show that the proposed structure is capable of lasing up to a maximum lattice temperature of ∼119 K at 4.8 THz. For future improvements of the device, we identify major performance-degrading factors of the proposed design

Local and global persistence exponents of two quenched continuous lattice spin models

Local and global persistence exponents associated with zero temperature quenched dynamics of two dimensional XY model and three dimensional Heisenberg model have been estimated using numerical simulations. We have used the method of block persistence to find both global and local exponents simultaneously (in a single simulation). Temperature universality of both the exponents for three dimensional Heisenberg model has been confirmed by simulating the stochastic (with noise) version of the equation of motion. The noise amplitudes added were small enough to retain the dynamics below criticality. In the second part of our work we have studied scaling associated with correlated persistence sites in the three dimensional Heisenberg model in the later stages of the dynamics. The relevant length scale associated with correlated persistent sites was found to behave in a manner similar to the dynamic length scale associated with the phase ordering dynamics.Comment: 20 pages, 7 figure

Model of Four Light Neutrinos in the Light of All Present Data

Motivated by existing and recent data on possible neutrino oscillations, we propose a model of four light neutrinos ($\nu_e, \nu_\mu, \nu_\tau$, and a singlet $\nu_S$) with a pattern of masses and mixing derivable from a $Z_5$ discrete symmetry and the seesaw mechanism. Atmospheric neutrino oscillations occur between $\nu_\mu$ and $\nu_\tau$ as pseudo-Dirac partners; whereas solar neutrino oscillations occur between $\nu_e$ and $\nu_S$, a linear combination of which is massless. Additional oscillations may occur between $\nu_e$ and $\nu_\mu$ to account for the recent observation of the LSND (Liquid Scintillator Neutrino Detector) experiment.Comment: Title changed, new (penultimate) paragraph added, Ref.[7] expanded, 12 pages, no figur

3DQ: Compact Quantized Neural Networks for Volumetric Whole Brain Segmentation

Model architectures have been dramatically increasing in size, improving performance at the cost of resource requirements. In this paper we propose 3DQ, a ternary quantization method, applied for the first time to 3D Fully Convolutional Neural Networks (F-CNNs), enabling 16x model compression while maintaining performance on par with full precision models. We extensively evaluate 3DQ on two datasets for the challenging task of whole brain segmentation. Additionally, we showcase our method's ability to generalize on two common 3D architectures, namely 3D U-Net and V-Net. Outperforming a variety of baselines, the proposed method is capable of compressing large 3D models to a few MBytes, alleviating the storage needs in space critical applications.Comment: Accepted to MICCAI 201

Heavy Triplet Leptons and New Gauge Boson

A heavy triplet of leptons $(\Sigma^+, \Sigma^0, \Sigma^-)_R$ per family is proposed as the possible anchor of a small seesaw neutrino mass. A new U(1) gauge symmetry is then also possible, and the associated gauge boson $X$ may be discovered at or below the TeV scale. We discuss the phenomenology of this proposal, with and without possible constraints from the NuTeV and atomic parity violation experiments, which appear to show small discrepancies from the predictions of the standard model.Comment: 20 pages including 4 figure

SUSY Contributions to RbR_b and Top Decay

I report on a systematic analysis of the MSSM parameter space to obtain the best SUSY solution to the $R_b$ anomaly within the constraint of top quark decay. Phenomenological implications for top decay and direct stop production at the Tevatron collider are discussed.Comment: Latex file (3 pages)+ 2 ps files containing figures. Invited talk at SUSY96, Maryland, May 199