Frequency‐Dependent Moment Tensors of Induced Microearthquakes

Analysis of 984 induced microearthquakes from The Geysers geothermal reservoir in California reveals that the retrieved moment tensors depend on the frequency band of the inverted waveforms. The observed dependence is more significant for the percentages of the double‐couple, compensated linear vector dipole, and isotropic (ISO) components than for the focal mechanisms. The average root‐mean‐square of the moment tensors obtained in different frequency bands is correlated with spectra of ambient noise. The percentages of double‐couple and ISO components tend to decrease and increase with the upper cutoff frequency (fu), respectively. This suggests that shear rupture radiates energy preferentially in a lower frequency band and tensile rupture in a higher frequency band. Events displaying a strong increase of the ISO with fu are confined within the same depth interval as the injection points. This might be related to the strong thermoelastic effects in the vicinity of injection points that promote opening of small cracks adjacent to the main fractures

Neutrinos from Early-Phase, Pulsar-Driven Supernovae

Neutron stars, just after their formation, are surrounded by expanding, dense, and very hot envelopes which radiate thermal photons. Iron nuclei can be accelerated in the wind zones of such energetic pulsars to very high energies. These nuclei photo-disintegrate and their products lose energy efficiently in collisions with thermal photons and with the matter of the envelope, mainly via pion production. When the temperature of the radiation inside the envelope of the supernova drops below $\sim 3\times 10^6$ K, these pions decay before losing energy and produce high energy neutrinos. We estimate the flux of muon neutrinos emitted during such an early phase of the pulsar - supernova envelope interaction. We find that a 1 km$^2$ neutrino detector should be able to detect neutrinos above 1 TeV within about one year after the explosion from a supernova in our Galaxy. This result holds if these pulsars are able to efficiently accelerate nuclei to energies $\sim 10^{20}$ eV, as postulated recently by some authors for models of Galactic acceleration of the extremely high energy cosmic rays (EHE CRs).Comment: 16 pages, 3 figures, revised version submitted to Ap

Realism, Objectivity, and Evaluation

I discuss Benacerraf's epistemological challenge for realism about areas like mathematics, metalogic, and modality, and describe the pluralist response to it. I explain why normative pluralism is peculiarly unsatisfactory, and use this explanation to formulate a radicalization of Moore's Open Question Argument. According to the argument, the facts -- even the normative facts -- fail to settle the practical questions at the center of our normative lives. One lesson is that the concepts of realism and objectivity, which are widely identified, are actually in tension

Expression of divIB of Bacillus subtilis during vegetative growth

Expression of the division initiation gene, divIB, of Bacillus subtilis vegetative growth was examined. lacZ fusion studies and transcription start point mapping have established that a sigma A promoter proximal to divIB is utilized in vivo. The -10 region of this promoter, which is located 93 bp upstream of the start codon, has been defined precisely by site-directed mutagenesis that destroys the promoter. Examination of transcripts by Northern (RNA) blotting has shown that there are at least two transcripts for divIB. The established proximal promoter was found to give rise to a very minor transcript which could not be convincingly demonstrated in wild-type cells but which became apparent upon insertion of a plasmid into the chromosome just upstream of this promoter. The major transcript for divIB originated from a site several kb upstream of the gene and is probably the same as the long polycistronic message also traversing the murD-spoVE-murG genes that was identified previously by others (A.D. Henriques, H. de Lencastre, and P.J. Piggot, Biochimie 74:735-748, 1992). Transcription from the proximal promoter alone, in an upstream-deletion mutant strain, provided sufficient DivIB for normal growth and division as well as sporulation

Mathematical modelling long-term effects of replacing Prevnar7 with Prevnar13 on invasive pneumococcal diseases in England and Wales

England and Wales recently replaced the 7-valent pneumococcal conjugate vaccine (PCV7) with its 13-valent equivalent (PCV13), partly based on projections from mathematical models of the long-term impact of such a switch compared to ceasing pneumococcal conjugate vaccination altogether. A compartmental deterministic model was used to estimate parameters governing transmission of infection and competition between different groups of pneumococcal serotypes prior to the introduction of PCV13. The best-fitting parameters were used in an individual based model to describe pneumococcal transmission dynamics and effects of various options for the vaccination programme change in England and Wales. A number of scenarios were conducted using (i) different assumptions about the number of invasive pneumococcal disease cases adjusted for the increasing trend in disease incidence prior to PCV7 introduction in England and Wales, and (ii) a range of values representing serotype replacement induced by vaccination of the additional six serotypes in PCV13. Most of the scenarios considered suggest that ceasing pneumococcal conjugate vaccine use would cause an increase in invasive pneumococcal disease incidence, while replacing PCV7 with PCV13 would cause an overall decrease. However, the size of this reduction largely depends on the level of competition induced by the additional serotypes in PCV13. The model estimates that over 20 years of PCV13 vaccination, around 5000–62000 IPD cases could be prevented compared to stopping pneumococcal conjugate vaccination altogether. Despite inevitable uncertainty around serotype replacement effects following introduction of PCV13, the model suggests a reduction in overall invasive pneumococcal disease incidence in all cases. Our results provide useful evidence on the benefits of PCV13 to countries replacing or considering replacing PCV7 with PCV13, as well as data that can be used to evaluate the cost-effectiveness of such a switch

Are the New Physics Contributions from the Left-Right Symmetric Model Important for the Indirect CP Violation in the Neutral B Mesons?

Several works analyzing the new physics contributions from the Left-Right Symmetric Model to the CP violation phenomena in the neutral B mesons can be found in the literature. These works exhibit interesting and experimentally sensible deviations from the Standard Model predictions but at the expense of considering a low right scale \upsilon_R around 1 TeV. However, when we stick to the more conservative estimates for \upsilon_R which say that it must be at least 10^7 GeV, no experimentally sensible deviations from the Standard Model appear for indirect CP violation. This estimate for \upsilon_R arises when the generation of neutrino masses is considered. In spite of the fact that this scenario is much less interesting and says nothing new about both the CP violation phenomenon and the structure of the Left-Right Symmetric Model, this possibility must be taken into account for the sake of completeness and when considering the see-saw mechanism that provides masses to the neutrino sector.Comment: LaTex file. 19 pages, 4 figures. Change in the way the paper address the problem. As a result, change in title, abstract, and some sections. Conclusions unchanged. Version to appear in Foundations of Physics Letter

Unified Universal Seesaw Models

A set of Grand Unified Theories based upon the gauge groups SU(5)_\L \times SU(5)_\R, SO(10)_\L \times SO(10)_\R and SU(4)_\C \times SU(4)_\L \times SU(4)_\R is explored. Several novel features distinguish these theories from the well-known $SU(5)$, $SO(10)$ and SU(4)_\C \times SU(2)_\L \times SU(2)_\R models which they generalize. Firstly, Standard Model quarks and leptons are accompanied by and mix with heavy SU(2)_\L \times SU(2)_\R singlet partners. The resulting fermion mass matrices are seesaw in form. Discrete parity symmetries render the determinants of these mass matrices real and eliminate CP violating gauge terms. The unified seesaw models consequently provide a possible resolution to the strong CP problem. Secondly, \sinsq at the unification scale is numerically smaller than the experimentally measured $Z$ scale value. The weak angle must therefore increase as it evolves down in energy. Finally, proton decay is suppressed by small seesaw mixing factors in all these theories.Comment: 22 pages with 2 figures not included but available upon request, CALT-68-185