Note on restoring manifest rotational symmetry in hyperfine and fine structure in light-front QED

We study the part of the renormalized, cutoff QED light-front Hamiltonian that does not change particle number. The Hamiltonian contains interactions that must be treated in second-order bound state perturbation theory to obtain hyperfine structure. We show that a simple unitary transformation leads directly to the familiar Breit-Fermi spin-spin and tensor interactions, which can be treated in degenerate first-order bound-state perturbation theory, thus simplifying analytic light-front QED calculations. To the order in momenta we need to consider, this transformation is equivalent to a Melosh rotation. We also study how the similarity transformation affects spin-orbit interactions.Comment: 17 pages, latex fil

Initial bound state studies in light-front QCD

We present the first numerical QCD bound state calculation based on a renormalization group-improved light-front Hamiltonian formalism. The QCD Hamiltonian is determined to second order in the coupling, and it includes two-body confining interactions. We make a momentum expansion, obtaining an equal-time-like Schrodinger equation. This is solved for quark-antiquark constituent states, and we obtain a set of self-consistent parameters by fitting B meson spectra.Comment: 38 pages, latex, 5 latex figures include

Isotopic studies in the natural sources of radium in groundwater in Illinois

Stable and radioactive isotopes in groundwater were studied in an investigation of the natural geologic sources of high concentrations of ²²⁶Ra and ²²⁸Ra in confined aquifers in the Cambrian and Ordovician bedrock of northern Illinois. The covariation of ¹⁸0 and D determined that the groundwater has a meteoric isotopic composition. Groundwater in unconfined aquifers has ¹⁸0 values (-6.6 to -7.9⁰/₀₀) that are similar to contemporary meteoric water. However, a source of recharge related to glaciation is required for groundwater in confined aquifers of the Cambrian and Ordovician that is significantly depleted in ¹⁸0 (¹⁸0 values range to -12.7⁰/₀₀ and are less than -9⁰/₀₀ over large regions) . The covariation of ³⁴S and ¹⁸0 in dissolved sulfates determined a mixing line between two sources; oxidation of sulfide minerals and dissolution of marine evaporites. Dissolved sulfates from evaporite sources are present in large concentrations in confined aquifers but are of a different isotopic composition than evaporites of Cambrian or Ordovician age. Glaciation may be important with regard to recharge of the sulfates. The ²³⁴U/²³⁸U activity ratio in groundwater from the Cambrian and Ordovician are unexpectedly high; values range from 2.1 to 40.7. The lowest ratios occur in primary recharge zones. In confined aquifers values are greater than 20 over large regions. Alpha recoil damage is a mechanism that contributes to the disequilibrium. However, the regional variation in activity ratios and in ²³⁴U concentrations supports the concept that glacial recharge has contributed to the high ratios. Radiological and geochemical mechanisms that partition ²³⁸U, ²³⁴U and ²³⁰Th on the sandstone matrix are important to the dissolved ²²⁶Ra concentration.U.S. Department of the InteriorU.S. Geological Surve

Increased intraventricular velocities An unrecognized cause of systolic murmur in adults

AbstractObjectives. The purpose of this study was to determine the frequency, clinical features and echocardiographic characteristics of increased intraventricular velocities (IIVs) in patients referred to the echocardiography laboratory for systolic murmur.Background. A subset of patients referred to the echocardiography laboratory for evaluation of a systolic murmur have IIVs in the absence of other recognized causes of systolic murmur.Methods. We prospectively studied echocardiograms from 108 consecutive patients referred for evaluation of a systolic murmur. Clinical data were obtained from patient examinations and medical records.Results. The sole explanation for systolic murmur was IIVs in 16.7% of referred patients. Compared with those without IIVs, patients with IIVs had a higher ejection fraction (EF) (58.7 ± 7.8% vs. 51.1 ± 12.5%, p < 0.001), percent fractional shortening (42.3 ± 9.7% vs. 31.0 ± 11.4%, p < 0.0001), left ventricular (LV) mass index (181 ± 70 vs. 152 ± 48 g/m2, p = 0.046) and prevalence of hypertension (73.3% vs. 51.7%, p = 0.043) and a lower prevalence of segmental wall motion abnormalities (2.2% vs. 39.3%, p < 0.001).Conclusions. Increased intraventricular velocities are a common cause of systolic murmur in this group of patients and should be included in the differential diagnosis of systolic murmurs in adults. The association of IIVs with LV hypertrophy should be a clinical consideration when these murmurs are identified

High-Pressure Neutron-Scattering Studies of Graphite and Stage-Two Graphite-SbCl₅

The longitudinal-acoustic (LA) phonons propagating along the c axis in highly oriented pyrolytic graphite (HOPG) were investigated as a function of pressure up to 20 kbar using inelastic-neutron-scattering techniques. The phonon frequencies varied as (P,q)=A(P)sin[c(P)q/2], where A(P) and c(P) indicate the pressure dependences of the zone-center LO frequency of B1g1 symmetry and of the c-axis lattice spacing, respectively. From the measurements, the mode Grüneisen parameter for the LA branch was estimated to be 1.5 x 10-2 kbar-1 (independent of q); the elastic constant C33 for HOPG was found to be 3.40 x 1011 dyn/cm2 at 1 bar with a pressure coefficient of (1/C33)(dC33/dP)=2.91 x 10-2 kbar-1. The measured c-axis spacings were 6.71 and 12.72 Å for HOPG and stage-2 SbCl5-intercalated graphite, respectively, at atmospheric pressure; the corresponding compressibilities (1/c)(dc/dP) were -2.24 x 10-3 kbar-1 (HOPG) and -2.28 x 10-3 kbar-1 (SbCl5). Elastic-neutron-scattering studies up to 20 kbar were undertaken to search for stage transformations, but no evidence of any phase transition was observed

Correlates of life expectancy in less developed countries

Analyses were performed to investigate several hypotheses concerning the multiple determinants of levels of life expectancy in developing countries in recent decades and some possible explanation for the observed variations in amount of gain in life expectancy from the 1950's to the 1970's. The findings were significant. For level of life expectancy the results of this present work conform by and large to results of other scholars in this area, although the present work is unique in that only developing countries were included. From the 1960's to the 1970's there has been a shift in the relative importance of economic indicators and general social indicators in favor of the social indicators. In the period 1960-1965 some 70% of the variation in levels of life expectancy was associated with per capita income and literacy rates in a ratio of about three to two in favor of the economic variable. By 1970-1975 the ratio has become six to one in favor of literacy. In addition, the multivariate model showed that the sanitation variables began to appear as significant correlates of levels of life expectancy in the more recent time period, playing a larger role than level of income per capita. Work pursued as part of a separate but concurrent project explored explicitly this three-way interaction between literacy, life expectancy and sanitation.For change in life expectancy from 1950 through 1970, associations were quite different. Per capita income was not associated with the absolute change in life expectancy, and the associations with literacy were much smaller than earlier observed with level of life expectancy at a point in time. In the multivariate model the primary correlates with change were the sanitation variables and health personnel as represented by population per midwife. Tests for such associations with variations in amount of gain in life expectancy have not been found in other literature and comparison with other findings can therefore not be made directly. The present work suggests that it may be lower skill levels of health manpower and activities in sanitation that are the main correlates in a multivariate model of absolute change in life expectancy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24048/1/0000297.pd

Rephasing Ion Packets in the Orbitrap Mass Analyzer to Improve Resolution and Peak Shape

A method is described to improve resolution and peak shape in the Orbitrap under certain experimental conditions. In these experiments, an asymmetric anharmonic axial potential was first produced in the Orbitrap by detuning the voltage on the compensator electrode, which results in broad and multiply split mass spectral peaks. An AC waveform applied to the outer electrode, 180° out of phase with ion axial motion and resonant with the frequency of ion axial motion, caused ions of a given m/z to be de-excited to the equator (z = 0) and then immediately re-excited. This process, termed “rephasing,” leaves the ion packet with a narrower axial spatial extent and frequency distribution. For example, when the Orbitrap axial potential is thus anharmonically de-tuned, a resolution of 124,000 to 171,000 is obtained, a 2- to 3-fold improvement over the resolution of 40,000 to 60,000 without rephasing, at 10 ng/μL reserpine concentration. Such a rephasing capability may ultimately prove useful in implementing tandem mass spectrometry (MS/MS) in the Orbitrap, bringing the Orbitrap\u27s high mass accuracy and resolution to bear on both the precursor and product ions in the same MS/MS scan and making available the collision energy regime of the Orbitrap, ∼1500 eV

Rephasing Ion Packets in the Orbitrap Mass Analyzer to Improve Resolution and Peak Shape

A method is described to improve resolution and peak shape in the Orbitrap under certain experimental conditions. In these experiments, an asymmetric anharmonic axial potential was first produced in the Orbitrap by detuning the voltage on the compensator electrode, which results in broad and multiply split mass spectral peaks. An AC waveform applied to the outer electrode, 180° out of phase with ion axial motion and resonant with the frequency of ion axial motion, caused ions of a given m/z to be de-excited to the equator (z = 0) and then immediately re-excited. This process, termed “rephasing,” leaves the ion packet with a narrower axial spatial extent and frequency distribution. For example, when the Orbitrap axial potential is thus anharmonically de-tuned, a resolution of 124,000 to 171,000 is obtained, a 2- to 3-fold improvement over the resolution of 40,000 to 60,000 without rephasing, at 10 ng/μL reserpine concentration. Such a rephasing capability may ultimately prove useful in implementing tandem mass spectrometry (MS/MS) in the Orbitrap, bringing the Orbitrap\u27s high mass accuracy and resolution to bear on both the precursor and product ions in the same MS/MS scan and making available the collision energy regime of the Orbitrap, ∼1500 eV

MyoD Synergizes with the E-protein HEB Beta to Induce Myogenic Differentiation

The MyoD family of basic helix-loop-helix transcription factors function as heterodimers with members of the E-protein family to induce myogenic gene activation. The E-protein HEB is alternatively spliced to generate alpha and beta isoforms. While the function of these molecules has been studied in other cell types, questions persist regarding the molecular functions of HEB proteins in skeletal muscle. Our data demonstrate that HEB alpha expression remains unchanged in both myoblasts and myotubes, whereas HEB beta is upregulated during the early phases of terminal differentiation. Upon induction of differentiation, a MyoD-HEB beta complex bound the E1 E-box of the myogenin promoter leading to transcriptional activation. Importantly, forced expression of HEB beta with MyoD synergistically lead to precocious myogenin expression in proliferating myoblasts. However, after differentiation, HEB alpha and HEB beta synergized with myogenin, but not MyoD, to activate the myogenin promoter. Specific knockdown of HEB beta by small interfering RNA in myoblasts blocked differentiation and inhibited induction of myogenin transcription. Therefore, HEB alpha and HEB beta play novel and central roles in orchestrating the regulation of myogenic factor activity through myogenic differentiation