Electronic Structure and Stability of Hydrogen Halides and of Complex Ions XO4

(1) It is shown that in the hydrogen halide molecules (internuclear distance r0) the proton penetrates the electronic shell of the anion to a depth which for the simplified case of spherical symmetry can be characterized by the condition: The amount of negative charge beyond the sphere of radius r0 equals −1e. (2) From the dipole moments μ=xer0 of the hydrogen halide molecules it can be concluded: The wave mechanical distribution of the negative charge of the free halide ions is changed by the introduction of the proton in such a way that the center of gravity of an amount of charge equal to —(1−x)e is shifted from the halogen nucleus to the proton. The fraction (1—x) increases with the electronic polarizability of the anion, and would be equal to 1 for an ion of infinitely large polarizability, leading to a completely unpolar type of binding in this case. (3) It is shown that for the complex ions SiO44—, PO43—, SO4=, and ClO4−, the gradation of the X☒O distances and of the molar dispersion can be easily understood from the point of view used in 1924 for the case of the molar refraction: These ions represent the result of the polarization of O= by Si4+, P5+, S6+, and Cl7+, and the X☒O binding in them shows gradual changes toward the unpolar type. (4) It is pointed out that the relatively unstable HI and ClO4− approach the unpolar type of binding more closely than any other of the compounds considered here. The generalization of this connection between instability and the degree of deformation of electronic shells explains why compounds like FO4− and BrO4− are unknown.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70366/2/JCPSA6-10-7-410-1.pd

Estimating genetic and non-genetic components of variance for fasting glucose levels in pedigrees ascertained through non-insulin dependent diabetes

Fasting glucose levels measured on 337 individuals in 14 pedigrees ascertained through a proband with non-inuslin dependent diabetes were used to estimate genetic and non-genetic components of variance under a multifactorial model of inheritance. In this sample genetic factors were important in controlling variation in basal carbohydrate metabolism, as represented by age-adjusted log-fasting glucose. There was no evidence that arbitrary sib common environments or arbitrary parent common environments accounted for significant portions of the variability in fasting glucose in these data. An arbitrary environment shared by parent and offspring, however, had a marginally significant impact on the likelihood. Parameter estimates obtained from multifactorial models analysed in this manner are sensitive to extreme phenotypic values, however, and caution must be exerciese in estimating total genetic variation. While additive genetic factors did account for a significant proportion of the total variation in fasting glucose, a large proportion remained unexplained.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66167/1/j.1469-1809.1982.tb01586.x.pd

Production of antihydrogen at reduced magnetic field for anti-atom trapping

We have demonstrated production of antihydrogen in a 1$,$T solenoidal magnetic field. This field strength is significantly smaller than that used in the first generation experiments ATHENA (3$,$T) and ATRAP (5$,$T). The motivation for using a smaller magnetic field is to facilitate trapping of antihydrogen atoms in a neutral atom trap surrounding the production region. We report the results of measurements with the ALPHA (Antihydrogen Laser PHysics Apparatus) device, which can capture and cool antiprotons at 3$,$T, and then mix the antiprotons with positrons at 1$,$T. We infer antihydrogen production from the time structure of antiproton annihilations during mixing, using mixing with heated positrons as the null experiment, as demonstrated in ATHENA. Implications for antihydrogen trapping are discussed

Quantum Fluctuations in the Chirped Pendulum

An anharmonic oscillator when driven with a fast, frequency chirped voltage pulse can oscillate with either small or large amplitude depending on whether the drive voltage is below or above a critical value-a well studied classical phenomenon known as autoresonance. Using a 6 GHz superconducting resonator embedded with a Josephson tunnel junction, we have studied for the first time the role of noise in this non-equilibrium system and find that the width of the threshold for capture into autoresonance decreases as the square root of T, and saturates below 150 mK due to zero point motion of the oscillator. This unique scaling results from the non-equilibrium excitation where fluctuations, both quantum and classical, only determine the initial oscillator motion and not its subsequent dynamics. We have investigated this paradigm in an electrical circuit but our findings are applicable to all out of equilibrium nonlinear oscillators.Comment: 5 pages, 4 figure

Incomplete Dissociation in Solutions of Strong Electrolytes

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70904/2/JCPSA6-9-3-283-1.pd

Antihydrogen formation dynamics in a multipolar neutral anti-atom trap

Antihydrogen production in a neutral atom trap formed by an octupole-based magnetic field minimum is demonstrated using field-ionization of weakly bound anti-atoms. Using our unique annihilation imaging detector, we correlate antihydrogen detection by imaging and by field-ionization for the first time. We further establish how field-ionization causes radial redistribution of the antiprotons during antihydrogen formation and use this effect for the first simultaneous measurements of strongly and weakly bound antihydrogen atoms. Distinguishing between these provides critical information needed in the process of optimizing for trappable antihydrogen. These observations are of crucial importance to the ultimate goal of performing CPT tests involving antihydrogen, which likely depends upon trapping the anti-atom

Search For Trapped Antihydrogen

We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.Comment: 12 pages, 7 figure

Neonatal diabetes mellitus with pancreatic agenesis in an infant with homozygous IPF-1 Pro63fsX60 mutation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75447/1/j.1399-5448.2009.00526.x.pd