The Historical Origin of the Pulfrich Effect: A Serendipitous Astronomic Observation at the Border of the Milky Way

Interested in star movement the founder of Heidelberg's astronomy observatory, Max Wolf, faced the dilemma that the hitherto used 'Blinkmikrosop' of his Institution was damaged beyond repair following the first world war. He therefore used a new method, stereoscopy, to systematically classify 1053 moving stars between 1915 and 1918. The key problem Wolf identified with the new method was that variation in brightness of the same star on different photographic plates gave rise to an illusory movement. This was a particularly frequent problem with smaller stars close to the very bright Milky Way such as those in the proximity of Cygni or fade-out stars such as R Coronae Borealis. Carl Pulfrich, the world-leading expert on stereoscopy at the time, picked up immediately on the technical limitations Wolf published on stereoscopy in 1920. Pulfrich, who was blind in one eye, could not see the effect himself and designed a projection device to demonstrate Wolf's serendipitous observation to an audience which was equipped with a monocular neutral density filter. Pulfrich performed detailed investigations on the relationship of spatial perception and object movement, naming the phenomenon stereo effect, but it became widely known as the Pulfrich effect. The neuro-anatomical basis of the Pulfrich effect lies in the joint encoding of motion and depth within the visual cortex. Recognising Pulfrich effect is relevant for the management of patients in whom pathology of the visual pathways impairs judgment of object movement/position (e.g., in traffic or sport). Fitting a unilateral tinted lens or contact lens in front of the good eye can abolish the problem

Orbital M1 versus E2 strength in deformed nuclei: A new energy weighted sum rule

Within the unified model of Bohr and Mottelson we derive the following linear energy weighted sum rule for low energy orbital 1$^+$ excitations in even-even deformed nuclei S_{\rm LE}^{\rm lew} (M_1^{\rm orb}) \cong (6/5) \epsilon (B(E2; 0^+_1 \rightarrow 2_1^+ K=0)/Z e^2^2) \mu^2_N with B(E2) the E2 strength for the transition from the ground state to the first excited state in the ground state rotational band, $$ the charge r.m.s. radius squared and $\epsilon$ the binding energy per nucleon in the nuclear ground state. It is shown that this energy weighted sum rule is in good agreement with available experimental data. The sum rule is derived using a simple ansatz for the intrinsic ground state wave function that predicts also high energy 1$^+$ strength at 2$\hbar \omega$ carrying 50\% of the total $m_1$ moment of the orbital M1 operator.Comment: REVTEX (3.0), 9 pages, RU924

Extended shell-model calculation for even N=82 isotones with realistic effective interactions

The shell model within the $2s1d0g_{7/2}0h_{11/2}$ shell is applied to calculate nuclear structure properties of the even Z=52 - 62, N=82 isotones. The results are compared with experimental data and with the results of a quasiparticle random-phase approximation (QRPA) calculation. The interaction used in these calculations is a realistic two-body G-matrix interaction derived from modern meson-exchange potential models for the nucleon-nucleon interaction. For the shell model all the two-body matrix elements are renormalized by the $\hat{Q}$-box method whereas for the QRPA the effective interaction is defined by the G-matrix.Comment: 25 pages, Elsevier latex style. Submitted to Nuclear Physics

Invasive aspergillosis mimicking metastatic lung cancer

In a patient with a medical history of cancer, the most probable diagnosis of an (18)FDG-avid pulmonary mass combined with intracranial abnormalities on brain imaging is metastasized cancer. However, sometimes a differential diagnosis with an infectious cause such as aspergillosis can be very challenging as both cancer and infection are sometimes difficult to distinguish. Pulmonary aspergillosis can present as an infectious pseudotumour with clinical and imaging characteristics mimicking lung cancer. Even in the presence of cerebral lesions, radiological appearance of abscesses can look like brain metastasis. These similarities can cause significant diagnostic difficulties with a subsequent therapeutic delay and a potential adverse outcome. Awareness of this infectious disease that can mimic lung cancer, even in an immunocompetent patient, is important. We report a case of a 65-year-old woman with pulmonary aspergillosis disseminated to the brain mimicking metastatic lung cancer

Phenomenology of the Deuteron Electromagnetic Form Factors

A rigorous extraction of the deuteron charge form factors from tensor polarization data in elastic electron-deuteron scattering, at given values of the 4-momentum transfer, is presented. Then the world data for elastic electron-deuteron scattering is used to parameterize, in three different ways, the three electromagnetic form factors of the deuteron in the 4-momentum transfer range 0-7 fm^-1. This procedure is made possible with the advent of recent polarization measurements. The parameterizations allow a phenomenological characterization of the deuteron electromagnetic structure. They can be used to remove ambiguities in the form factors extraction from future polarization data.Comment: 18 pages (LaTeX), 2 figures Feb. 25: minor changes of content and in Table

High-energy scissors mode

All the orbital M1 excitations, at both low and high energies, obtained from a rotationally invariant QRPA, represent the fragmented scissors mode. The high-energy M1 strength is almost purely orbital and resides in the region of the isovector giant quadrupole resonance. In heavy deformed nuclei the high-energy scissors mode is strongly fragmented between 17 and 25 MeV (with uncertainties arising from the poor knowledge of the isovector potential). The coherent scissors motion is hindered by the fragmentation and $B(M1) < 0.25 \; \mu^2_N$ for single transitions in this region. The $(e,e^{\prime})$ cross sections for excitations above 17 MeV are one order of magnitude larger for E2 than for M1 excitations even at backward angles.Comment: 20 pages in RevTEX, 5 figures (uuencoded,put with 'figures') accepted for publication in Phys.Rev.

Transition Rates between Mixed Symmetry States: First Measurement in 94Mo

The nucleus 94Mo was investigated using a powerful combination of gamma-singles photon scattering experiments and gamma-gamma-coincidence studies following the beta-decay of 94mTc. The data survey short-lived J^pi=1+,2+ states and include branching ratios, E2/M1 mixing ratios, lifetimes, and transition strengths. The mixed-symmetry (MS) 1+ scissors mode and the 2+ MS state are identified from M1 strengths. A gamma transition between MS states was observed and its rate was measured. Nine M1 and E2 strengths involving MS states agree with the O(6) limit of the interacting boson model-2 using the proton boson E2 charge as the only free parameter.Comment: 9 pages, 3 PostScript figures included, ReVTeX, accepted for publication in Physical Review Letters, tentatively scheduled for August 9, 199

A precise measurement of the deuteron elastic structure function A(Q^2)

The A(Q^2) structure function in elastic electron-deuteron scattering was measured at six momentum transfers Q^2 between 0.66 and 1.80 (GeV/c)^2 in Hall C at Jefferson Laboratory. The scattered electrons and recoil deuterons were detected in coincidence, at a fixed deuteron angle of 60.5 degrees. These new precise measurements resolve discrepancies between older sets of data. They put significant constraints on existing models of the deuteron electromagnetic structure, and on the strength of isoscalar meson exchange currents.Comment: 3 LaTeX pages plus 2 PS figure

Measurement of Tensor Polarization in Elastic Electron-Deuteron Scattering at Large Momentum Transfer

Tensor polarization observables (t20, t21 and t22) have been measured in elastic electron-deuteron scattering for six values of momentum transfer between 0.66 and 1.7 (GeV/c)^2. The experiment was performed at the Jefferson Laboratory in Hall C using the electron HMS Spectrometer, a specially designed deuteron magnetic channel and the recoil deuteron polarimeter POLDER. The new data determine to much larger Q^2 the deuteron charge form factors G_C and G_Q. They are in good agreement with relativistic calculations and disagree with pQCD predictions.Comment: 5 pages, 4 figures, for associated informations, see http://isnwww.in2p3.fr/hadrons/t20/t20_ang.html clarification about several topics, one figure has been had, extraction of form factors use AQ interpolation in our Q2 range onl

Nuclear Scissors Mode with Pairing

The coupled dynamics of the scissors mode and the isovector giant quadrupole resonance are studied using a generalized Wigner function moments method taking into account pair correlations. Equations of motion for angular momentum, quadrupole moment and other relevant collective variables are derived on the basis of the time dependent Hartree-Fock-Bogoliubov equations. Analytical expressions for energy centroids and transitions probabilities are found for the harmonic oscillator model with the quadrupole-quadrupole residual interaction and monopole pairing force. Deformation dependences of energies and $B(M1)$ values are correctly reproduced. The inclusion of pair correlations leads to a drastic improvement in the description of qualitative and quantitative characteristics of the scissors mode.Comment: 36 pages, 5 figures, the results of calculation by another method and the section concerning currents are adde