A Progress Report on the Study of Perch Movement in Lake Okoboji, Dickinson County, Iowa

Until recently, very little quantitative work has been done on the daily or short term movements of fresh water fish. Investigations by Hasler and Bardach (1949) have verified the existence of a diurnal movement of the yellow perch (Perca flavescens Mitchill) in Lake Mendota, Wisconsin. The present paper reports the results obtained from an investigation of the movements of yellow perch in Lake Okoboji, Dickinson County, Iowa. The investigation was undertaken in the summer of 1950 at the Iowa Lakeside Laboratory, and was primarily an attempt to ascertain: 1) do these fish undergo a diurnal movement, 2) is there a pattern to this movement, and 3) if they move regularly, what is the reason for this movement. The methods employed in this investigation were patterned after those used on Lake Mendota. The authors wish to thank Dr. John E. Bardach of the Iowa Lakeside Laboratory staff, for his guidance and assistance in this undertaking

The Large-Scale Distribution and Motions of Older Stars in Orion

We review the current knowledge of the population of `older' stars in the Orion OB1 association, specifically those in subgroups 1a and 1b. We briefly outline the history of the subject and then continue with a summary of the present state of knowledge of the early-type stars in Orion OB1. New results from the Hipparcos parallaxes and proper motions will be presented. The main result is that subgroup 1a is located at about 330 pc from the Sun, much closer than the previously determined distance, and about 100 pc distant from the other subgroups of the association and the Orion molecular clouds. Unfortunately, due to the unfavorable kinematics of the association with respect to the Galactic background, Hipparcos proper motions do not allow a clear kinematic separation of the association from the field. For this purpose accurate and homogeneous radial velocities are needed. Traditionally, the massive O and B stars have received most of the attention in the studies of OB associations. However, we will present results showing that significant numbers of low-mass stars are associated with Orion OB1. Unbiased, optically complete, spectroscopic and photometric surveys of areas within subgroups 1a and 1b have the potential to determine the complete low-mass stellar population, down to the brown dwarf limit. This will provide much insight into the overall initial mass function and studies of the kinematics of the low-mass stars will yield insights into the dispersal of the association.Comment: To appear in The Orion Complex Revisited, eds. M. J. McCaughrean & A. Burkert (San Francisco, ASP), gzipped tar-file, 22 pages 7 EPS-figures, LaTeX using paspconf.sty and psfig.tex. Wrongly quoted errors on the average parallaxes of the Orion OB1 subgroups were corrected (Section 4

Current Studies in Japanese Law

Over the past fifteen years there has been a remarkable growth in the study of Japanese law in the United States. The foundation was laid during the late 1950\u27s when the Harvard-Michigan-Stanford program brought together Japanese legal specialists and their American counterparts for study and research. At the end of this program a major conference was held, and the resulting publication, Law in Japan, continues to serve as a point of departure in descriptive studies of Japanese law. During the 1960\u27s interest in Japan continued to develop among law faculty members, but an even more important development was the increase in the number of students coming to the law school who already had some Japanese language and area training. With these students as a nucleus, a few law schools have begun to offer work in Japanese law. Some of these courses have been taught by visiting Japanese professors, and a few are taught regularly by Americans trained in Japanese law. At the same time, the Japanese legal system has been studied by many non-lawyers, such as political scientists, sociologists, and anthropologists. Constitutional law, family law, and criminal law have been analyzed as political and social phenomena in studies which have gone beyond legal rules to origins and practices. The four papers in this volume represent these various developments. One is by a visiting scholar, two were written by students in a course dealing with Japanese law, and one is part of a doctoral thesis in anthropology.https://repository.law.umich.edu/books/1108/thumbnail.jp

Panchromatic Imaging of a Transitional Disk: The Disk of GM Aur in Optical and FUV Scattered Light

We have imaged GM Aur with HST, detected its disk in scattered light at 1400A and 1650A, and compared these with observations at 3300A, 5550A, 1.1 microns, and 1.6 microns. The scattered light increases at shorter wavelengths. The radial surface brightness profile at 3300A shows no evidence of the 24AU radius cavity that has been previously observed in sub-mm observations. Comparison with dust grain opacity models indicates the surface of the entire disk is populated with sub-micron grains. We have compiled an SED from 0.1 microns to 1 mm, and used it to constrain a model of the star+disk system that includes the sub-mm cavity using the Monte Carlo Radiative Transfer code by Barbara Whitney. The best-fit model image indicates that the cavity should be detectable in the F330W bandpass if the cavity has been cleared of both large and small dust grains, but we do not detect it. The lack of an observed cavity can be explained by the presence of sub-microns grains interior to the sub-mm cavity wall. We suggest one explanation for this which could be due to a planet of mass <9 Jupiter masses interior to 24 AU. A unique cylindrical structure is detected in the FUV data from the Advanced Camera for Surveys/Solar Blind Channel. It is aligned along the system semi-minor axis, but does not resemble an accretion-driven jet. The structure is limb-brightened and extends 190 +/- 35 AU above the disk midplane. The inner radius of the limb-brightening is 40 +/- 10 AU, just beyond the sub-millimeter cavity wall.Comment: 40 pages, 11 figures, 4 tables, accepted to Ap

Meson-exchange enhancement in first-forbidden β\beta -transitions: the case of 50^{50}K and 38^{38}Ca

The $\beta$- decay of $^{50}$K and $^{38}$Ca have been investigated with the main motive of determining more accurately the first-forbidden $\beta$- branches, in particular the rank-zero, $\Delta$J = 0, $\,\beta$ -transitions. $^{50}$K and $^{38}$Ca have been produced by fragmentation of U and Ti targets respectively, with a 1 GeV proton beam and subsequent on-line mass separation. For $^{50}$K, $\gamma$-ray spectroscopy, as well as delayed neutron spectroscopy by time of flight, were carried out to obtain a detailed decay scheme to 20 (bound and unbound) levels in $^{50}$Ca. The level structur e of $^{50}$Ca can be compared to recent calculations which incorporate 1p1h excitations from the f$_{7/2}$ shell. The first-forbidden $\beta^-$ transition $^{50}$ K(0$^-$)$\,\to{}^{50}$Ca(0$^+$) g.s. has been evaluated for the first time by a direct measurement of $\beta$- and $\gamma$- activities. Its importance (61.0 $\pm$ 7.4$\%$) is interpreted as an effect of the meson-exchange current (MEC) l eading to an enhancement factor of 62(5)$\%$ in comparison with the value predicted by shell-model calculations using the impulse approximation. For the $^{38}$ Ca$\,\to{}^{38}$K decay, chemical selec tive production was obtained through separation of the molecular ion CaF$^+$ without contamination by isobars. In these conditions, the measurement of very weak $\beta$-branches, at a level of 10$^{-3}\%$ decays, could be made and a limit, at the 2$\sigma$-confidence level, has been obtained for the 0$^+\to$ 0$^-$ branch to the level at E$_x$ = 2993 keV (I$_\beta$ < 0.0046$\%$). Imp lications of these results on the general trend of meson-exchange enhancements of first-forbidden transitions within the framework of the spherical shell model are discussed

Discriminating among Earth composition models using geo-antineutrinos

It has been estimated that the entire Earth generates heat corresponding to about 40 TW (equivalent to 10,000 nuclear power plants) which is considered to originate mainly from the radioactive decay of elements like U, Th and K, deposited in the crust and mantle of the Earth. Radioactivity of these elements produce not only heat but also antineutrinos (called geo-antineutrinos) which can be observed by terrestrial detectors. We investigate the possibility of discriminating among Earth composition models predicting different total radiogenic heat generation, by observing such geo-antineutrinos at Kamioka and Gran Sasso, assuming KamLAND and Borexino (type) detectors, respectively, at these places. By simulating the future geo-antineutrino data as well as reactor antineutrino background contributions, we try to establish to which extent we can discriminate among Earth composition models for given exposures (in units of kt$\cdot$ yr) at these two sites on our planet. We use also information on neutrino mixing parameters coming from solar neutrino data as well as KamLAND reactor antineutrino data, in order to estimate the number of geo-antineutrino induced events.Comment: 24 pages, 10 figures, final version to appear in JHE

Spitzer Space Telescope study of disks in the young σ\sigma Orionis cluster

We report new Spitzer Space Telescope observations from the IRAC and MIPS instruments of the young (~ 3 Myr) sigma Orionis cluster. We identify 336 stars as members of the cluster using optical and near-infrared color magnitude diagrams. Using the spectral energy distribution (SED) slopes in the IRAC spectral range, we place objects in several classes: non-excess stars, stars with optically thick disks(like classical T Tauri stars), class I (protostellar) candidates, and stars with ``evolved disks''; the last exhibit smaller IRAC excesses than optically thick disk systems. In general, this classification agrees with the location expected in IRAC-MIPS color-color diagrams for these objects. We find that the evolved disk systems are mostly a combination of objects with optically thick but non-flared disks, suggesting grain growth and/or settling, and transition disks, systems in which the inner disk is partially or fully cleared of small dust. In all, we identify 7 transition disk candidates and 3 possible debris disk systems. As in other young stellar populations, the fraction of disks depends on the stellar mass, ranging from ~10% for stars in the Herbig Ae/Be mass range (>2 msun) to ~35% in the T Tauri mass range (1-0.1 msun). We find that the disk fraction does not decrease significantly toward the brown dwarf candidates (<0.1 msun). The IRAC infrared excesses found in stellar clusters and associations with and without central high mass stars are similar, suggesting that external photoevaporation is not very important in many clusters. Finally, we find no correlation between the X-ray luminosity and the disk infrared excess, suggesting that the X-rays are not strongly affected by disk accretion.Comment: 44pages, 17 figures. Sent to Ap

Comparison of Age and Growth Parameters of Invasive Red Lionfish (\u3ci\u3ePterois volitans\u3c/i\u3e) Across the Northern Gulf of Mexico

Invasive red lionfish (Pterois volitans) have spread rapidly throughout the northern Gulf of Mexico (GOM) partly because of their high growth rate. Red lionfish were collected from the northern GOM across 3 ecological regions from 2012 through 2015. For male and female red lionfish, relationships between weight and total length (TL) were differnt by ecological region. Males acheives a greater mean weight adjusted for TL (333.6 g [standar errer (SE) 3.6]) than females (195.1 g [SE 3.7]). A subsample of 1607 pairs of sagittal otoliths (from 744 males, 716 females, and 147 fish of unknown or undetermined sex) was used to assign ages. Ages ranged from 0.0 to 4.5 years (mean: 1.4 years), and these estimated ages and the dates of capture for specimens confirm the presence of red lionfish in the northern GOM in 2008, 2 years prior to the first detection of this species there. There were differences in age and rowth between sexes within and among ecological regions, with males achieving higher growth rates and larger asympototic lengths than females (all comparions:

Light propagation in non-trivial QED vacua

Within the framework of effective action QED, we derive the light cone condition for homogeneous non-trivial QED vacua in the geometric optics approximation. Our result generalizes the ``unified formula'' suggested by Latorre, Pascual and Tarrach and allows for the calculation of velocity shifts and refractive indices for soft photons travelling through these vacua. Furthermore, we clarify the connection between the light velocity shift and the scale anomaly. This study motivates the introduction of a so-called effective action charge that characterizes the velocity modifying properties of the vacuum. Several applications are given concerning vacuum modifications caused by, e.g., strong fields, Casimir systems and high temperature.Comment: 13 pages, REVTeX, 3 figures, to appear in Phys. Rev.