Phonons in intrinsic Josephson systems with parallel magnetic field

Subgap resonances in the I-V curves of layered superconductors are explained by the coupling between Josephson oscillations and phonons with dispersion in c-direction. In the presence of a magnetic field applied parallel to the layers additional structures due to fluxon motion appear. Their coupling with phonons is investigated theoretically and a shift of the phonon resonances in strong magnetic fields is predicted.Comment: Invited Paper to the "2nd International Symposium on Intrinsic Josephson Effects and Plasma Oscillations in High-Tc Superconductors", 22-24 August 2000, Sendai, Japan, to be published in Physica

Optical Resonances in Reflectivity near Crystal Modes with Spatial Dispersion

We study the effect of spatial dispersion of crystal modes on optical properties such as the reflectivity $R$. As an example for isotropic media, we investigate the simplest model for phonons in ionic crystals and compare with previous results for highly anisotropic plasmons, which are now understood from a more general point of view. As a consequence of the wave vector dependence of the dielectric function small changes in the lineshape are predicted. Beyond that, if the frequency of minimal $R$ is near a pole of the dispersionless dielectric function, the relative amplitude of dips in $R$ with normal and anomalous dispersion differ significantly, if dissipation and disorder are low.Comment: 4 pages, 7 eps figures, minor change

Electronic compressibility and charge imbalance relaxation in cuprate superconductors

In the material SmLa$_{1-x}$Sr$_x$CuO$_{4-\delta}$ with alternating intrinsic Josephson junctions we explain theoretically the relative amplitude of the two plasma peaks in transmission by taking into account the spatial dispersion of the Josephson Plasma Resonance in $c$ direction due to charge coupling. From this and the magnetic field dependence of the plasma peaks in the vortex solid and liquid states it is shown that the electronic compressibility of the CuO$_2$ layers is consistent with a free electron value. Also the London penetration depth $\lambda_{ab} \approx 1100 {\rm \AA}$ near $T_c$ can be determined. The voltage response in the $IV$-curve of a Bi$_2$Sr$_2$CaCu$_2$O$_8$ mesa due to microwave irradiation or current injection in a second mesa is related to the nonequilibrium charge imbalance of quasiparticles and Cooper pairs and from our experimental data the relaxation time $\sim 100 {\rm ps}$ is obtained.Comment: 2 pages, 2 figures, phc-proc4-auth.cls, to be published in Physica C as a proceeding of M2S-HTSC Rio 200

Standardized Pearson type 3 density function area tables

Tables constituting extension of similar tables published in 1936 are presented in report form. Single and triple parameter gamma functions are discussed. Report tables should interest persons concerned with development and use of numerical analysis and evaluation methods

Use of accelerometry to investigate physical activity in dogs receiving chemotherapy

Objectives: To perform a preliminary study to assess whether single-agent palliative or adjuvant chemotherapy has an impact on objectively measured physical activity in dogs. Methods: Fifteen dogs with neoplasia (treatment group) wore ActiGraph™ accelerometers for 5-day periods before, during and after receiving single-agent adjuvant or palliative chemotherapy. Mean 5-day total physical activity and time spent in three different intensities of activity (sedentary, light-moderate and vigorous) before, during and after receiving chemotherapy were compared to a group of 15 healthy dogs (control group). Results were also compared within the treatment group across time. Results: Prior to chemotherapy, treated dogs tended to be less active than control dogs. Treatment group dogs were slightly more active at restaging than they were prior to treatment but had similar activity levels to control dogs. Marked effects of chemotherapy on physical activity were not detected. Physical activity was slightly lower in treated dogs during chemotherapy when compared to control dogs but there was a slight increase in physical activity of treated dogs during chemotherapy when compared with pretreatment recordings. There was little change in the mean 5-day total physical activity between treated dogs during chemotherapy and at restaging but a mild decrease in time spent sedentary and increase in time spent in light-moderate activity at this comparison of time points. Clinical Significance: Single-agent adjuvant or palliative chemotherapy had minimal impact on physical activity levels in dogs with neoplasia

Coupling of intrinsic Josephson oscillations in layered superconductors by charge fluctuations

The coupling of Josephson oscillations in layered superconductors is studied with help of a tunneling Hamiltonian formalism. The general form of the current density across the barriers between the superconducting layers is derived. The induced charge fluctuations on the superconducting layers lead to a coupling of the Josephson oscillations in different junctions. A simplified set of equations is then used to study the non-linear dynamics of the system. In particular the influence of the coupling on the current-voltage characteristics is investigated and upper limits for the coupling strength are estimated from a comparison with experiments on cuprate superconductors.Comment: To be published in proceedings of SPIE conference San Diego 199

Evolution and development of scyphozoan jellyfish

© The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biological Reviews 93 (2018): 1228-1250, doi:10.1111/brv.12393.Scyphozoan jellyfish, or scyphomedusae, are conspicuous members of many ocean ecosystems, and have large impacts on human health and industry. Most scyphomedusae are the final stage in a complex life cycle that also includes two intermediate stages: the larval planula and benthic polyp. In species with all three life‐cycle stages, the metamorphosis of a polyp into a juvenile scyphomedusa (ephyra) is termed strobilation, and polyps can produce one ephyra (termed monodisc strobilation) or many ephyrae (termed polydisc strobilation). In contrast to species with planula, polyp and medusa stages, a handful of scyphozoan species possess modified life cycles with reduced or absent stages. The evolutionary patterns associated with strobilation and life‐cycle type have not been thoroughly investigated, and many studies of ephyra development and strobilation induction are not yet synthesized. Herein, I place the development of scyphomedusae in an evolutionary context. I first review the current evolutionary hypotheses for Scyphozoa. Next, I review what is known about scyphomedusa development across a broad diversity of species, including the first signs of strobilation, the formation of strobila segments, and the morphogenesis of ephyrae. I then review cases where the canonical scyphozoan life cycle has been modified, and take advantage of phylogenetic hypotheses to place these observations in an evolutionary context. I show that the evolution of monodisc strobilation occurred at least twice, and that the loss of intermediate life‐cycle stages occurred several times independently; by contrast, the reduction of the medusa stage appears to have occurred within a single clade. I then briefly review the major natural cues of strobilation induction. Finally, I summarize what is currently known about the molecular mechanisms of strobilation induction and ephyra development. I conclude with suggestions for future directions in the field.Support for this work came from the National Science Foundation (NSF) Graduate Research Fellowship under grant number DGE - 1058262, and a Brown University DissertationDevelopment Grant from the Bushnell Research and Education Fund

Flight Instructor Grading Bias Involving Students With Racial, Ethnic and Gender Differences

Of 1038 naval flight students, 943 Caucasian males, 23 African American males, 41 Hispanic males and 31 females had their flight training performance analyzed. Aviation selection test scores, academic grades and flight grades were examined to determine objective and subjective grading reliability. To facilitate cross comparison all test scores were transformed into Navy Standard Scores with a mean of 50 and standard deviation of 10. It was hypothesized that flight instructor grading bias would appear as inconsistent means and/or variances compared to objectively derived aptitude and academic performance. Comparing flight instructor subjectively determined flight grades to objectively determined aptitude scores and academic grades revealed no significant difference for Caucasians, African American or Hispanic males. However, there was significant difference between female aptitude scores and flight grades. Female flight grades were significantly higher than aptitude scores would predict. No other differences were found. Conclusions about flight instructor grading bias is fairly clear. For males there appears to be no bias. For females the bias is positive, ie., higher flight grades than would be predicted by their flight aptitude scores. In general, flight instructors grading patterns were extremely consistent when compared to objectively determined aptitude and academic test scores

Perceptions of Superintendents, Principals, and Teachers Concerning the Effectiveness of Mid-Illinois Educational Service Center #15

Educational Service Centers were established throughout Illinois by the State Board of Education as a result of the passage of Senate Bill 730 in 1985. The purpose of this field study was to determine the perceived effectiveness of programs and services provided by Mid-Illinois Educational Service Center #15 from superintendents\u27, principals\u27, and teachers\u27 perspectives. Superintendents, principals, and randomly selected teachers in public school districts serviced by Educational Service Center #15 were given a questionnaire to determine their perceptions about the quality of the service they had received. Interviews with the director of Educational Service Center #15 and a review of its goals and directives were utilized in the development of the questionnaire. The data gathered by the survey were tabulated and analyzed to determine what percentage of superintendents, principals and teachers were aware of and utilizing the programs and services provided by Educational Service Center #15. The perceived effectiveness of each of these programs/services was then analyzed and reported. The results and conclusions of this study indicate the need for workshops to help teachers become more aware of the programs and services provided by Educational Service Center #15

Perceptions of Superintendents, Principals, and Teachers Concerning the Effectiveness of Mid-Illinois Educational Service Center #15

Educational Service Centers were established throughout Illinois by the State Board of Education as a result of the passage of Senate Bill 730 in 1985. The purpose of this field study was to determine the perceived effectiveness of programs and services provided by Mid-Illinois Educational Service Center #15 from superintendents\u27, principals\u27, and teachers\u27 perspectives. Superintendents, principals, and randomly selected teachers in public school districts serviced by Educational Service Center #15 were given a questionnaire to determine their perceptions about the quality of the service they had received. Interviews with the director of Educational Service Center #15 and a review of its goals and directives were utilized in the development of the questionnaire. The data gathered by the survey were tabulated and analyzed to determine what percentage of superintendents, principals and teachers were aware of and utilizing the programs and services provided by Educational Service Center #15. The perceived effectiveness of each of these programs/services was then analyzed and reported. The results and conclusions of this study indicate the need for workshops to help teachers become more aware of the programs and services provided by Educational Service Center #15