A test of adverse selection in the market for experienced workers

We show that in labor market models with adverse selection, otherwise observationally equivalent workers will experience less wage growth following a period in which they change jobs than following a period in which they do not. We find little or no evidence to support this prediction. In most specifications the coefficient has the opposite sign, sometimes statistically significantly so. When consistent with the prediction, the estimated effects are small and statistically insignificant. We consistently reject large effects in the predicted direction. We argue informally that our results are also problematic for a broader class of models of competitive labor markets.Othe

Simultaneous Solar Maximum Mission (SMM) and very large array observations of solar active regions

The research deals mainly with Very Large Array and Solar Maximum Mission observations of the ubiquitous coronal loops that dominate the structure of the low corona. As illustrated, the observations of thermal cyclotron lines at microwave wavelengths provide a powerful new method of accurately specifying the coronal magnetic field strength. Processes are delineated that trigger solar eruptions from coronal loops, including preburst heating and the magnetic interaction of coronal loops. Evidence for coherent burst mechanisms is provided for both the Sun and nearby stars, while other observations suggest the presence of currents that may amplify the coronal magnetic field to unexpectedly high levels. The existence is reported of a new class of compact, variable moving sources in regions of apparently weak photospheric field

Precision CW laser automatic tracking system investigated

Precision laser tracker capable of tracking a low acceleration target to an accuracy of about 20 microradians rms is being constructed and tested. This laser tracking has the advantage of discriminating against other optical sources and the capability of simultaneously measuring range

Study of non-equilibrium effects and thermal properties of heavy ion collisions using a covariant approach

Non-equilibrium effects are studied using a full Lorentz-invariant formalism. Our analysis shows that in reactions considered here, no global or local equilibrium is reached. The heavier masses are found to be equilibrated more than the lighter systems. The local temperature is extracted using hot Thomas Fermi formalism generalized for the case of two interpenetrating pieces of nuclear matter. The temperature is found to vary linearly with bombarding energy and impact parameter whereas it is nearly independent of the mass of the colliding nuclei. This indicates that the study of temperature with medium size nuclei is also reliable. The maximum temperatures obtained in our approach are in a nice agreement with earlier calculations of other approaches. A simple parametrization of maximal temperature as a function of the bombarding energy is also given.Comment: LaTex-file, 17 pages, 8 figures (available upon request), Journal of Physics G20 (1994) 181

The Chandra Detection of Galactic Center X-ray Features G359.89-0.08 and G359.54+0.18

We report on the detection of two elongated X-ray features G359.89-0.08 and G359.54+0.18 in the Galactic center (GC) region using the Chandra X-ray Observatory. G359.89-0.08 is an elongated X-ray feature located $\sim$2\arcmin in projection south of the center of the Galaxy, SgrA$^*$. This X-ray feature source is partially coincident with a slightly curved (``wisp''-like) non-thermal radio source. The X-ray spectrum of G359.89-0.08 can be best characterized as non-thermal, with a photon index of 2. The morphological and spectral characteristics of the X-ray and radio emission associated with G359.89-0.08 are best interpreted as the synchrotron emission from a ram-pressure confined pulsar wind nebula. G359.54+0.18 is one of the most prominent radio non-thermal filaments (NTFs) in the GC region, located $\sim$30\arcmin in projection from SgrA$^*$. A narrow ($\sim$10\arcsec) filament of X-ray emission appears to arise from one of the two strands that comprise the radio NTF. Although the photon statistics are poor for this source, the X-ray emission is also likely to be non-thermal in nature. Several models for the production of X-ray emission in G359.54+0.18 are discussed.Comment: 19 pages with 6 figures included, accepted by A

Discovery of a Non-Thermal Galactic Center Filament (G358.85+0.47) Parallel to the Galactic Plane

We report the discovery of a new non-thermal filament, G358.85+0.47, the ``Pelican'', located ~225 pc in projection from SgrA, and oriented parallel to the Galactic plane. VLA continuum observations at 20 cm reveal that this 7' (17.5 pc) structure bends at its northern extension and is comprised of parallel strands, most apparent at its ends. Observations at 6 and 3.6 cm reveal that the Pelican is a synchrotron-emitting source and is strongly linearly polarized over much of its extent. The spectral index of the filament changes from alpha(20/6)=-0.8 to alpha(6/3.6)=-1.5. The rotation measures exhibit a smooth gradient, with values ranging from -1000 rad/m2 to +500 rad/m2. The intrinsic magnetic field is well-aligned along the length of the filament. Based on these properties, we classify the Pelican as one of the non-thermal filaments unique to the Galactic center. Since these filaments (most of which are oriented perpendicular to the Galactic plane) are believed to trace the overall magnetic field in the inner Galaxy, the Pelican is the first detection of a component of this field parallel to the plane. The Pelican may thus mark a transition region of the magnetic field orientation in the inner kiloparsec of the Galaxy.Comment: 6 pages, 4 figures, to appear in ApJ Letters; Figs. 2 & 3 are color .ps files and best viewed in colo

Interpretation of transverse tune spectra in a heavy-ion synchrotron at high intensities

Two different tune measurement systems have been installed in the GSI heavy-ion synchrotron SIS-18. Tune spectra are obtained with high accuracy using these fast and sensitive systems. Besides the machine tune, the spectra contain information about the intensity dependent coherent tune shift and the incoherent space charge tune shift. The space charge tune shift is derived from a fit of the observed shifted positions of the synchrotron satellites to an analytic expression for the head-tail eigenmodes with space charge. Furthermore, the chromaticity is extracted from the measured head-tail mode structure. The results of the measurements provide experimental evidence of the importance of space charge effects and head-tail modes for the interpretation of transverse beam signals at high intensity

On the Quantum Invariant for the Brieskorn Homology Spheres

We study an exact asymptotic behavior of the Witten-Reshetikhin-Turaev invariant for the Brieskorn homology spheres $\Sigma(p_1,p_2,p_3)$ by use of properties of the modular form following a method proposed by Lawrence and Zagier. Key observation is that the invariant coincides with a limiting value of the Eichler integral of the modular form with weight 3/2. We show that the Casson invariant is related to the number of the Eichler integrals which do not vanish in a limit $\tau\to N \in \mathbb{Z}$. Correspondingly there is a one-to-one correspondence between the non-vanishing Eichler integrals and the irreducible representation of the fundamental group, and the Chern-Simons invariant is given from the Eichler integral in this limit. It is also shown that the Ohtsuki invariant follows from a nearly modular property of the Eichler integral, and we give an explicit form in terms of the L-function.Comment: 26 pages, 2 figure