Standard Model parameters in the tadpole-free pure MS‾\overline{\rm{MS}} scheme

We present an implementation and numerical study of the Standard Model couplings, masses, and vacuum expectation value (VEV), using the pure $\overline{\rm{MS}}$ renormalization scheme based on dimensional regularization. Here, the $\overline{\rm{MS}}$ Lagrangian parameters are treated as the fundamental inputs, and the VEV is defined as the minimum of the Landau gauge effective potential, so that tadpole diagrams vanish, resulting in improved convergence of perturbation theory. State-of-the-art calculations relating the $\overline{\rm{MS}}$ inputs to on-shell observables are implemented in a consistent way within a public computer code library, SMDR (Standard Model in Dimensional Regularization), which can be run interactively or called by other programs. Included here for the first time are the full 2-loop contributions to the Fermi constant within this scheme and studies of the minimization condition for the VEV at 3-loop order with 4-loop QCD effects. We also implement, and study the scale dependence of, all known multi-loop contributions to the physical masses of the Higgs boson, the W and Z bosons, and the top quark, the fine structure constant and weak mixing angle, and the renormalization group equations and threshold matching relations for the gauge couplings, fermion masses, and Yukawa couplings.Comment: 26 pages. The SMDR code can be obtained from http://www.niu.edu/spmartin/SMDR or http://faculty.otterbein.edu/drobertson/SMDR v2: references adde

Targeted gene disruption of the endogenous c-abl locus by homologous recombination with DNA encoding a selectable fusion protein

We have introduced a substitution mutation into the c-abl locus of murine embryonic stem cells by homologous recombination between exogenously added DNA and the endogenous gene. Model constructs were initially generated that consisted of a promoterless selectable neomycin resistance marker inserted into the v-abl gene of the complete Abelson murine leukemia virus genome, designed to be expressed either as a fusion protein or by translational restart. Tests of these viral genomes for transmission of v-abl and neo markers showed more stable coexpression in a protein fusion construct. The neo fusion was subcloned from this v-abl construct into a promoterless c-abl fragment, and the resulting DNA was used to transform embryonic stem cells. Direct screening of genomic DNAs showed that a high proportion of drug-resistant clones arose from homologous recombination into the endogenous c-abl locus

On the Conditional and Unconditional Type I Error Rates and Power of Tests in Linear Models with Heteroscedastic Errors

Preliminary tests for homoscedasticity may be unnecessary in general linear models. Based on Monte Carlo simulations, results suggest that when testing for differences between independent slopes, the unconditional use of weighted least squares regression and HC4 regression performed the best across a wide range of conditions

Subseasonal-to-interdecadal variability of the Australian monsoon over North Queensland

Daily rainfall occurrence and amount at 11 stations over North Queensland are examined for summers 1958–1998, using a Hidden Markov Model (HMM). Daily rainfall variability is described in terms of the occurrence of five discrete ‘weather states’, identified by the HMM. Three states are characterized respectively by very wet, moderately wet, and dry conditions at most stations; two states have enhanced rainfall along the coast and dry conditions inland. Each HMM rainfall state is associated with a distinct atmospheric circulation regime. The two wet states are accompanied by monsoonal circulation patterns with large-scale ascent, low-level inflow from the north-west, and a phase reversal with height; the dry state is characterized by circulation anomalies of the opposite sense. Two of the states show significant associations with midlatitude synoptic waves. Variability of the monsoon on time-scales from subseasonal to interdecadal is interpreted in terms of changes in the frequency of occurrence of the five HMM rainfall states. Large subseasonal variability is identified in terms of active and break phases, and a highly variable monsoon onset date. The occurrence of the very wet and dry states is somewhat modulated by the Madden–Julian oscillation. On interannual time-scales, there are clear relationships with the El Niño–Southern Oscillation and Indian Ocean sea surface temperatures (SSTs). Interdecadal monsoonal variability is characterized by stronger monsoons during the 1970s, and weaker monsoons plus an increased prevalence of drier states in the later part of the record. Stochastic simulations of daily rainfall occurrence and amount at the 11 stations are generated by introducing predictors based on large-scale precipitation from (a) reanalysis data, (b) an atmospheric general circulation model (GCM) run with observed SST forcing and (c) antecedent June–August Pacific SST anomalies. The reanalysis large-scale precipitation yields relatively accurate station-level simulations of the interannual variability of daily rainfall amount and occurrence, with rainfall intensity less well simulated. At some stations, interannual variations in 10-day dry-spell frequency are also simulated reasonably well. The interannual quality of the simulations is markedly degraded when the GCM simulations are used as inputs, while antecedent Pacific SST inputs yield an anomaly correlation skill comparable to that of the GCM

Subseasonal-to-interdecadal variability of the Australian monsoon over North Queensland

Daily rainfall occurrence and amount at 11 stations over North Queensland are examined for summers 1958–1998, using a Hidden Markov Model (HMM). Daily rainfall variability is described in terms of the occurrence of five discrete ‘weather states’, identified by the HMM. Three states are characterized respectively by very wet, moderately wet, and dry conditions at most stations; two states have enhanced rainfall along the coast and dry conditions inland. Each HMM rainfall state is associated with a distinct atmospheric circulation regime. The two wet states are accompanied by monsoonal circulation patterns with large-scale ascent, low-level inflow from the north-west, and a phase reversal with height; the dry state is characterized by circulation anomalies of the opposite sense. Two of the states show significant associations with midlatitude synoptic waves. Variability of the monsoon on time-scales from subseasonal to interdecadal is interpreted in terms of changes in the frequency of occurrence of the five HMM rainfall states. Large subseasonal variability is identified in terms of active and break phases, and a highly variable monsoon onset date. The occurrence of the very wet and dry states is somewhat modulated by the Madden–Julian oscillation. On interannual time-scales, there are clear relationships with the El Niño–Southern Oscillation and Indian Ocean sea surface temperatures (SSTs). Interdecadal monsoonal variability is characterized by stronger monsoons during the 1970s, and weaker monsoons plus an increased prevalence of drier states in the later part of the record. Stochastic simulations of daily rainfall occurrence and amount at the 11 stations are generated by introducing predictors based on large-scale precipitation from (a) reanalysis data, (b) an atmospheric general circulation model (GCM) run with observed SST forcing and (c) antecedent June–August Pacific SST anomalies. The reanalysis large-scale precipitation yields relatively accurate station-level simulations of the interannual variability of daily rainfall amount and occurrence, with rainfall intensity less well simulated. At some stations, interannual variations in 10-day dry-spell frequency are also simulated reasonably well. The interannual quality of the simulations is markedly degraded when the GCM simulations are used as inputs, while antecedent Pacific SST inputs yield an anomaly correlation skill comparable to that of the GCM

Spontaneous Symmetry Breaking of phi4(1+1) in Light Front Field Theory

We study spontaneous symmetry breaking in phi^4_(1+1) using the light-front formulation of the field theory. Since the physical vacuum is always the same as the perturbative vacuum in light-front field theory the fields must develop a vacuum expectation value through the zero-mode components of the field. We solve the nonlinear operator equation for the zero-mode in the one-mode approximation. We find that spontaneous symmetry breaking occurs at lambda_critical = 4 pi(3+sqrt 3), which is consistent with the value lambda_critical = 54.27 obtained in the equal time theory. We calculate the value of the vacuum expectation value as a function of the coupling constant in the broken phase both numerically and analytically using the delta expansion. We find two equivalent broken phases. Finally we show that the energy levels of the system have the expected behavior within the broken phase.Comment: 17 pages, OHSTPY-HEP-TH-92-02

Embryonic Lethality in Mice Homozygous for a Targeted Disruption of the N-myc Gene

The N-myc gene encodes a putative transcription factor that is thought to function in the regulation of gene expression during cell differentiation and/or growth. To examine the role of N-myc during development, we have used targeted mutagenesis in embryonic stem cells to produce a mouse line that carries an N-myc null allele. Mice homozygous for the mutation died between 10.5 and 12.5 days of gestation. Histological analysis of mutant embryos revealed that organs and tissues expected at these stages of development were present. However, multiple defects were observed, primarily in tissues and organs that normally express N-myc. In particular, mutant hearts were underdeveloped, often retaining the S-shape more typical of 9-day-old embryos. In addition, cranial and spinal ganglia were reduced in size and/or cellularity. Most of the noted defects were more consistent with a role of N-myc in proliferation of precursor populations than with a block in differentiation per se, at least at these early stages. These results demonstrate that N-myc plays an essential role during development and clearly confirm that N-myc has a physiological function that is distinct from that of the other myc-family genes

Lattice-stiffening transition in copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%)

We report the discovery of a compressibility phase transition at 160 K in crystalline copolymer films of vinylidene fluoride (70%) with trifluoroethylene (30%). This phase transition is distinct from the known bulk ferroelectric-paraelectric phase transition at 353 K and surface ferroelectric phase transition at 295 K. The new phase transition is characterized by an increase in the effective Debye temperature from 48 to 245 K along the 〈010〉 direction as the temperature falls below 160 K. This phase transition is evident in neutron scattering, x-ray diffraction, angle-resolved photoemission, and in the dipole active phonon modes in electron energy-loss spectroscopy. © 1999 The American Physical Society