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

Pressure Broadening and Shift of the Cesium D\u3csub\u3e1\u3c/sub\u3e Transition by the Noble Gases and N\u3csub\u3e2\u3c/sub\u3e, H\u3csub\u3e2\u3c/sub\u3e, HD, D\u3csub\u3e2\u3c/sub\u3e, CH\u3csub\u3e4\u3c/sub\u3e, C\u3csub\u3e2\u3c/sub\u3eH\u3csub\u3e6\u3c/sub\u3e, CF\u3csub\u3e4\u3c/sub\u3e, and \u3csup\u3e3\u3c/sup\u3eHe

The pressure broadening and shift rates for the cesium D1 (62P1/2 ← 6 2S1/2) transition with the noble gases and N2, H2, HD, D2, CH4, C2H6, CF4, and 3He were obtained for pressures less than 300 torr at temperatures under 65 °C by means of laser absorption spectroscopy. The collisional broadening rate, γL, for He, Ne, Ar, Kr, Xe, N2, H2, HD, D2, CH4, C2H6, CF4, and 3He are 24.13, 10.85, 18.31, 17.82, 19.74, 16.64, 20.81, 20.06, 18.04, 29.00, 26.70, 18.84, and 26.00 MHz/torr, respectively. The corresponding pressure-induced shift rates, δ, are 4.24, −1.60, −6.47, −5.46, −6.43, −7.76, 1.11, 0.47, 0.00, −9.28, −8.54, −6.06, and 6.01 MHz/torr. These rates have then been utilized to calculate Lennard-Jones potential coefficients to quantify the interatomic potential surfaces. The broadening cross section has also been shown to correlate with the polarizability of the collision partner

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

Particle number size distributions in urban air before and after volatilisation

Aerosol particle number size distributions (size range 0.003–10 μm) in the urban atmosphere of Augsburg (Germany) were examined with respect to the governing anthropogenic sources and meteorological factors. The two-year average particle number concentration between November 2004 and November 2006 was 12 200 cm−3, i.e. similar to previous observations in other European cities. A seasonal analysis yielded twice the total particle number concentrations in winter as compared to summer as consequence of more frequent inversion situations and enhanced particulate emissions. The diurnal variations of particle number were shaped by a remarkable maximum in the morning during the peak traffic hours. After a mid-day decrease along with the onset of vertical mixing, an evening concentration maximum could frequently be observed, suggesting a re-stratification of the urban atmosphere. Overall, the mixed layer height turned out to be the most influential meteorological parameter on the particle size distribution. Its influence was even greater than that of the geographical origin of the prevailing synoptic-scale air mass. Size distributions below 0.8 μm were also measured downstream of a thermodenuder (temperature: 300 °C), allowing to retrieve the volume concentration of non-volatile compounds. The balance of particle number upstream and downstream of the thermodenuder suggests that practically all particles >12 nm contain a non-volatile core while additional nucleation of particles smaller than 6 nm could be observed after the thermodenuder as an interfering artifact of the method. The good correlation between the non-volatile volume concentration and an independent measurement of the aerosol absorption coefficient (R2=0.9) suggests a close correspondence of the refractory and light-absorbing particle fractions. Using the "summation method", an average diameter ratio of particles before and after volatilisation could be determined as a function of particle size. The results indicated that particles >60 nm contain a significantly higher fraction of non-volatile compounds, most likely black carbon, than particles <60 nm. The results are relevant for future health-related studies in that they explore the size distribution and time-dependent behaviour of the refractory component of the urban aerosol over an extended time period

Evaluación de la competencia clínica de tutores de residentes de medicina familiar y comunitaria

ObjetivoDescribir la primera experiencia de una evaluación clínica objetiva y estructurada (ECOE) a tutores de residentes realizada en la comunidad autónoma de AndalucíaDiseñoObservacional descriptivoEmplazamientoUnidad Docente de Medicina Familiar y Comunitaria de HuelvaParticipantesTutores de residentes de medicina familiar y comunitariaMediciones principalesLos componentes competenciales que se consensuaron y ponderaron fueron los siguientes: anamnesis, exploración física, comunicación,habilidades técnicas, manejo, atención a la familia y actividades preventivas. La selección de las 10 situaciones clínicas de las que constaba la prueba se realizó utilizando unos criterios de priorización según la prevalencia, gravedad clínica, importancia de la prevención y del diagnóstico precoz, complejidad del caso, evaluación de la capacidad resolutiva del médico y simplicidad evaluativaResultadosRealizaron la ECOE 13 tutores. La edad media ± desviación estándar de los participantes fue de 42,8 ± 3,64 años. La prueba tuvo un coeficiente de fiabilidad (alfa de Cronbach) de 0,73. Por lo que se refiere a los resultados por participantes, la media global fue de 73 ± 6,2. Al analizar los resultados para los diferentes componentes competenciales, los mejores resultados se obtuvieron en la atención a la familia, la comunicación y las habilidades técnicasConclusionesLas pruebas de evaluación clínica objetiva y estructurada pueden ser útiles para la valoración de los tutores, con el objetivo de orientar su formación en los puntos débiles e incluso para, en un futuro no muy lejano, servir como instrumento para acreditar y reacreditar a los tutores de residentes de medicina familiar y comunitariaObjectivesWe show the first experience of the application of an objetive and structured clinical evaluation (OSCE) procedure to family medicine trainers, that has been carried out in Andalucia. The objective is to use a competence evaluation instrument that, in the short term, will be used not only for trainer accreditation but also for other public sanitary professionalsParticipantsTutors of family and commnity medicine residentsDesignObservational descriptiveSettingEducational unity of family medicinePrincipal measurementsThe competencial components to be assessed are the following: anamnesis, physical exploration, communication, technical skill, management, family attention y preventive activities. The clinical situations were selected using the following priority criteria: prevalence, clinical gravity, prevention and early diagnosis importance, case complexity, doctor's capacity of evaluation and simplicityResultsThirteen family medicine trainers took part in the OSCE. Their average age was 42.8±3.6 years. The test had an overall reliability coefficient (Cronbach's alpha) of 0.73. The overall mean score of the participants was 73±6.2. The best results about the competencial components were family attention, communication and technical skillConclusionsThe OSCE can be a convenient tool for family medical trainer evaluation, helping to orientate their education in the weak points and, in the near future, it can also be used as an instrument do accredit family medicine trainer

Auxotrophic interactions: A stabilizing attribute of aquatic microbial communities?

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Johnson, W. M., Alexander, H., Bier, R. L., Miller, D. R., Muscarella, M. E., Pitz, K. J., & Smith, H. Auxotrophic interactions: A stabilizing attribute of aquatic microbial communities? FEMS Microbiology Ecology, (2020): fiaa115, doi: 10.1093/femsec/fiaa115.Auxotrophy, or an organism's requirement for an exogenous source of an organic molecule, is widespread throughout species and ecosystems. Auxotrophy can result in obligate interactions between organisms, influencing ecosystem structure and community composition. We explore how auxotrophy-induced interactions between aquatic microorganisms affect microbial community structure and stability. While some studies have documented auxotrophy in aquatic microorganisms, these studies are not widespread, and we therefore do not know the full extent of auxotrophic interactions in aquatic environments. Current theoretical and experimental work suggests that auxotrophy links microbial community members through a complex web of metabolic dependencies. We discuss the proposed ways in which auxotrophy may enhance or undermine the stability of aquatic microbial communities, highlighting areas where our limited understanding of these interactions prevents us from being able to predict the ecological implications of auxotrophy. Finally, we examine an example of auxotrophy in harmful algal blooms to place this often theoretical discussion in a field context where auxotrophy may have implications for the development and robustness of algal bloom communities. We seek to draw attention to the relationship between auxotrophy and community stability in an effort to encourage further field and theoretical work that explores the underlying principles of microbial interactions.This work was supported by the National Science Foundation [OCE-1356192]

Chemical Kinetic Modeling of Combustion of Automotive Fuels

The objectives of this report are to: (1) Develop detailed chemical kinetic reaction models for components of fuels, including olefins and cycloalkanes used in diesel, spark-ignition and HCCI engines; (2) Develop surrogate mixtures of hydrocarbon components to represent real fuels and lead to efficient reduced combustion models; and (3) Characterize the role of fuel composition on production of emissions from practical automotive engines

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

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