Uniqueness of static spherically symmetric vacuum solutions in the IR limit of Ho\v{r}ava-Lifshitz gravity

We investigate static spherically symmetric vacuum solutions in the IR limit of projectable nonrelativistic quantum gravity, including the renormalisable quantum gravity recently proposed by Ho\v{r}ava. It is found that the projectability condition plays an important role. Without the cosmological constant, the spacetime is uniquely given by the Schwarzschild solution. With the cosmological constant, the spacetime is uniquely given by the Kottler (Schwarzschild-(anti) de Sitter) solution for the entirely vacuum spacetime. However, in addition to the Kottler solution, the static spherical and hyperbolic universes are uniquely admissible for the locally empty region, for the positive and negative cosmological constants, respectively, if its nonvanishing contribution to the global Hamiltonian constraint can be compensated by that from the nonempty or nonstatic region. This implies that static spherically symmetric entirely vacuum solutions would not admit the freedom to reproduce the observed flat rotation curves of galaxies. On the other hand, the result for locally empty regions implies that the IR limit of nonrelativistic quantum gravity theories does not simply recover general relativity but includes it.Comment: 10 pages, accepted for publication in International Journal of Modern Physics

Physics at the Linear Collider

The physics at the planned $e^+e^-$ colliders is discussed around three main topics corresponding to different manifestations of symmetry breaking: $W$ physics in the no Higgs scenario, studies of the properties of the Higgs and precision tests of SUSY. A comparison with the LHC is made for all these cases. The $\gamma \gamma$ mode of the linear collider will also be reviewed.Comment: 31 pages, 12 figures. Invited talk given at the Fifth Workshop on High Energy Physics Phenomenology, Inter-University Centre for Astronomy and Astrophysics, Pune, India, January 12 - 26, 199

Electron-Transport Properties of Na Nanowires under Applied Bias Voltages

We present first-principles calculations on electron transport through Na nanowires at finite bias voltages. The nanowire exhibits a nonlinear current-voltage characteristic and negative differential conductance. The latter is explained by the drastic suppression of the transmission peaks which is attributed to the electron transportability of the negatively biased plinth attached to the end of the nanowire. In addition, the finding that a voltage drop preferentially occurs on the negatively biased side of the nanowire is discussed in relation to the electronic structure and conduction.Comment: 4 pages, 6 figure

Local ras and ros in the hypertrophic differentiation of chondrocytes

Newsletter of the Boston University School of Medicine, Student American Medical Association (SAMA

The Life Course of a Standard-Bearer: A Nonroyal Elite Burial at the Maya Archaeological Site of El Palmar, Mexico

Inspired by life course and osteobiography approaches, this article explores the life and death of an individual associated with the lakam title (“banner” in Colonial Yukatek Maya; thus, a “standard-bearer”), a nonroyal elite of Late Classic period Maya society (AD 600–850). Although these elites are depicted on polychrome vessels and carved monuments, little is known about their life experiences and mortuary practices. The present analysis centers on an individual found at Structure GZ1, a temple with a hieroglyphic stairway, at the Maya archaeological site of El Palmar, Mexico. Using osteological, archaeological, and epigraphic data as different lines of evidence, we examine the relationship of the individual to his affiliated group. At the time of interment, there were a wide array of social, cultural, and political events both shaping and reshaping the body and identities of the individual during a period of political turbulence. Inspirado por los enfoques del curso de la vida y osteobiografía, este artículo explora la vida y muerte de un individuo asociado con el título lakam (“bandera” en Yukateka maya colonial, por lo tanto, “abanderado”), o una élite no-real de la sociedad maya del período Clásico tardío (600–850 dC). Aunque estas élites se representan en las vasijas policromadas y monumentos tallados, casi no se saben sobre sus experiencias de vida y práctica mortuoria. El presente análisis se centra en un individuo encontrado en la Estructura GZ1, un templo con una escalinata jeroglífica, en el sitio arqueológico maya de El Palmar, México. A través de los datos osteológicos, arqueológicos y epigráficos como diferentes líneas de evidencia, examinamos la relación del individuo con su grupo afiliado. En el momento del entierro, hubo una amplia gama de eventos sociales, culturales y políticos que dieron forma y remodelaron el cuerpo y las identidades del individuo durante un período de turbulencia política.Ye

Dynamically Induced Multi-Channel Kondo Effect

We study how the multi-channel Kondo effect is dynamically induced to affect the photoemission and the inverse photoemission spectrum when an electron is emitted from (or added to) the completely screened Kondo impurity with spin $S>1/2$. The spectrum thereby shows a power-law edge singularity characteristic of the multi-channel Kondo model. We discuss this anomalous behavior by using the exact solution of the multi-channel Kondo model and boundary conformal field theory. The idea is further applied to the photoemission for quantum spin systems, in which the edge singularity is controlled by the dynamically induced overscreening effect with a mobile Kondo impurity.Comment: 6 pages, 4 figures, submitted to PR

Sneutrino Mass Measurements at e+e- Linear Colliders

It is generally accepted that experiments at an e+e- linear colliders will be able to extract the masses of the selectron as well as the associated sneutrinos with a precision of ~ 1% by determining the kinematic end points of the energy spectrum of daughter electrons produced in their two body decays to a lighter neutralino or chargino. Recently, it has been suggested that by studying the energy dependence of the cross section near the production threshold, this precision can be improved by an order of magnitude, assuming an integrated luminosity of 100 fb^-1. It is further suggested that these threshold scans also allow the masses of even the heavier second and third generation sleptons and sneutrinos to be determined to better than 0.5%. We re-examine the prospects for determining sneutrino masses. We find that the cross sections for the second and third generation sneutrinos are too small for a threshold scan to be useful. An additional complication arises because the cross section for sneutrino pair to decay into any visible final state(s) necessarily depends on an unknown branching fraction, so that the overall normalization in unknown. This reduces the precision with which the sneutrino mass can be extracted. We propose a different strategy to optimize the extraction of m(\tilde{\nu}_\mu) and m(\tilde{\nu}_\tau) via the energy dependence of the cross section. We find that even with an integrated luminosity of 500 fb^-1, these can be determined with a precision no better than several percent at the 90% CL. We also examine the measurement of m(\tilde{\nu}_e) and show that it can be extracted with a precision of about 0.5% (0.2%) with an integrated luminosity of 120 fb^-1 (500 fb^-1).Comment: RevTex, 46 pages, 15 eps figure