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Crystallization of calcite from amorphous calcium carbonate: earthworms show the way
No abstract available
Solar Neutrinos from CNO Electron Capture
The neutrino flux from the sun is predicted to have a CNO-cycle contribution
as well as the known pp-chain component. Previously, only the fluxes from beta+
decays of 13N, 15O, and 17F have been calculated in detail. Another neutrino
component that has not been widely considered is electron capture on these
nuclei. We calculate the number of interactions in several solar neutrino
detectors due to neutrinos from electron capture on 13N, 15O, and 17F, within
the context of the Standard Solar Model. We also discuss possible non-standard
models where the CNO flux is increased.Comment: 4 pages, 1 figure, submitted to Phys. Rev. C; v2 has minor changes
including integration over solar volume and addition of missing reference to
previous continuum electron capture calculation; v3 has minor changes
including addition of references and the correction of a small (about 1%)
numerical error in the table
Synchronizing Sequencing Software to a Live Drummer
Copyright 2013 Massachusetts Institute of Technology. MIT allows authors to archive published versions of their articles after an embargo period. The article is available at
A Cosmic Battery Reconsidered
We revisit the problem of magnetic field generation in accretion flows onto
black holes owing to the excess radiation force on electrons. This excess force
may arise from the Poynting-Robertson effect.
Instead of a recent claim of the generation of dynamically important magnetic
fields, we establish the validity of earlier results from 1977 which show only
small magnetic fields are generated.
The radiative force causes the magnetic field to initially grow linearly with
time. However, this linear growth holds for only a {\it restricted} time
interval which is of the order of the accretion time of the matter.
The large magnetic fields recently found result from the fact that the linear
growth is unrestricted.
A model of the Poynting-Robertson magnetic field generation close to the
horizon of a Schwarzschild black hole is solved exactly using General
Relativity, and the field is also found to be dynamically insignificant.
These weak magnetic fields may however be important as seed fields for
dynamos.Comment: Astrophysical Journal (accepted
Caries in children with and without orofacial clefting:A systematic review and meta-analysis
This systematic review compared children's primary dentition caries experience for those with cleft lip and/or palate (CL/P) and without. Four databases were searched without date restriction for; cross-sectional studies comparing caries experience for children with CL/P to those without. Screening, data extraction and risk assessment were carried out independently (in duplicate). Meta-analyses used a random-effects model. Twenty studies (21 reports) fitting the inclusion criteria comprised 4647 children in primary dentition from 12 countries. For dmft (n = 3016 children; 15 groups), CL/P mean = 3.2; standard deviation = 2.22 and no CL/P mean dmft = 2.5; sd 1.53. For dmfs (n = 1095 children; 6 groups), CL/P mean = 4; sd = 3.5 and no CL/P mean = 3; sd = 2.8. For % caries experience (n = 1094 children; 7 groups), CL/P mean = 65%; sd = 20.8 and no CL/P mean = 52%; sd = 28.1. Meta-analysis showed higher caries experience in children with CL/P, standardised mean difference = 0.46; 95% CI = 0.15, 0.77. Studies' risk of bias was high (n = 7), medium (nâ10) and low (n = 3). Children with CL/P had higher caries experience compared to those without CLP
About the Use of Perfusion-Weighted Magnetic Resonance Imaging to Define Patterns of Neonatal Hypoxic-Ischemic Encephalopathy
A Method for Combining Isolates of Phytophthora sojae to Screen for Novel Sources of Resistance to Phytophthora Stem and Root Rot in Soybean
Soybean cultivars with specific single resistance genes (Rps) are grown to reduce yield loss due to Phytophthora stem and root rot caused by the oomycete pathogen Phytophthora sojae. To identify novel Rps loci, soybean lines are often screened several times, each time with an isolate of P. sojae that differs in virulence on various Rps genes. The goal of this study was to determine whether several isolates of P. sojae that differ in virulence on Rpsgenes could be combined into a single source of inoculum and used to screen soybean lines for novel Rps genes. A set of 14 soybean differential lines, each carrying a specific Rps gene, was inoculated with three isolates of P. sojae, which differed in virulence on 6 to 10 Rps genes, individually or in a 1:1:1 mixture. Inoculum containing the 1:1:1 mixture of isolates was virulent on 13 Rps genes. The mixed-inoculum method was used to screen 1,019 soybean accessions in a blind assay for novel sources of resistance. In all, 17% of Glycine max accessions and 11% of G. soja accessions were resistant (â€30% dead plants), suggesting that these accessions may carry a novel Rps gene or genes. Advantages of combining isolates into a single source of inoculum include reduced cost, ability to screen soybean germplasm with inoculum virulent on all known Rps genes, and ease of identifying novel sources of resistance. This study is a precursor to identifying novel sources of resistance to P. sojae in soybean using RXLR effectors
Fabrication of bismuth nanowires with a silver nanocrystal shadowmask
We fabricated bismuth (Bi) nanowires with low energy electron beam lithography using silver (Ag) nanocrystal shadowmasks and a subsequent chlorine reactive ion etching. Submicron-size metal contacts on the single Bi nanowire were successfully prepared by in situ focused ion beam metal deposition for transport measurements. The temperature dependent resistance measurements on the 50 nm wide Bi nanowires showed that the resistance increased with decreasing temperature, which is characteristic of semiconductors and insulators
Status of the Standard Solar Model Prediction of Solar Neutrino Fluxes
The Standard Solar Model (BP04) predicts a total 8B neutrino flux that is
17.2% larger than measured in the salt phase of the SNO detector (and if it
were significant it will indicate oscillation to sterile neutrinos). Hence it
is important to examine in details uncertainties (and values) of inputs to the
SSM. Currently, the largest fractional uncertainty is due to the new evaluation
of the surface composition of the sun. We examine the nuclear input on the
formation of solar 8B [S17(0)] and demonstrate that it is still quite uncertain
due to ill known slope of the measured astrophysical cross section factor and
thus ill defined extrapolation to zero energy. This yields an additional
reasonably estimated uncertainty due to extrapolation of +0.0 -3.0 eV-b (+0%
-14%). Since a large discrepancy exists among measured as well as among
predicted slopes, the value of S17(0) is dependent on the choice of data and
theory used to extrapolate S17(0). This situation must be alleviated by new
measurement(s). The "world average" is driven by the Seattle result due to the
very small quoted uncertainty, which we however demonstrate it to be an
over-estimated accuracy. We propose more realistic error bars for the Seattle
results based on the published Seattle data.Comment: Fifth International Conferenceon Non-Accelerator New Physics, Dubna,
June 20-25, 2005. Work Supported by USDOE Grant No. DE-FG02-94ER4087
Interacting Constituents in Cosmology
Universe evolution, as described by Friedmann's equations, is determined by
source terms fixed by the choice of pressure energy-density equations
of state . The usual approach in Cosmology considers equations of
state accounting only for kinematic terms, ignoring the contribution from the
interactions between the particles constituting the source fluid. In this work
the importance of these neglected terms is emphasized. A systematic method,
based on the Statistical Mechanics of real fluids, is proposed to include them.
A toy-model is presented which shows how such interaction terms can engender
significant cosmological effects.Comment: 24 pages, 6 figures. It includes results presented in "Cosmic
Acceleration from Elementary Interactions" [arXiv:gr-qc/0512135]. Citations
added in v.
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