Gravity device Patent

Gravity device for accurate and rapid indication of relative gravity conditions aboard accelerating carrie

Global Mapping Function (GMF): A new empirical mapping function based on numerical weather model data

Troposphere mapping functions are used in the analyses of Global Positioning System and Very Long Baseline Interferometry observations to map a priori zenith hydrostatic and wet delays to any elevation angle. Most analysts use the Niell Mapping Function (NMF) whose coefficients are determined from site coordinates and the day of year. Here we present the Global Mapping Function (GMF), based on data from the global ECMWF numerical weather model. The coefficients of the GMF were obtained from an expansion of the Vienna Mapping Function (VMF1) parameters into spherical harmonics on a global grid. Similar to NMF, the values of the coefficients require only the station coordinates and the day of year as input parameters. Compared to the 6-hourly values of the VMF1 a slight degradation in short-term precision occurs using the empirical GMF. However, the regional height biases and annual errors of NMF are significantly reduced with GMF

Beginning at the End: Reimagining the Dissertation Committee, Reimagining Careers

In this article, we forward a perspective on interdisciplinarity and diversity that reconsiders the notion of expertise in order to unstick discussions of graduate education reform that have been at an impasse for some fortyfive years. As research problems have become increasingly complex so has demand for scholars who specialize narrowly within a discipline and who understand the importance of contributions from other disciplines. In light of this, we reimagine the dissertation committee as a group of diverse participants from within and beyond the academy who contribute their knowledge and skills to train the next generation of scholars and researchers to be members of interdisciplinary teams. Graduate students, then, are not expected to be interdisciplinary themselves, but to work in interdisciplinary and diverse teams to discover new insights on their research areas and to prepare for careers interacting with a range of academic and non-academic stakeholders

Job polarization has squeezed the American middle class

Has the decline in manufacturing and clerical jobs been responsible for the lagging wages of middleskill workers in the United States? To answer this question, Michael Boehm compares the occupational choices and earnings of survey respondents in the 1980s and today. The decline of the middle class has been much debated in the United States and elsewhere in recent years. The first important component of this decline is the fall in the number of well-paid middle-skill jobs in manufacturing and clerical occupations since the 1980s

Constraining Dark Matter-Neutrino Interactions using the CMB and Large-Scale Structure

We present a new study on the elastic scattering cross section of dark matter (DM) and neutrinos using the latest cosmological data from Planck and large-scale structure experiments. We find that the strongest constraints are set by the Lyman-alpha forest, giving sigma_{DM-neutrino} < 10^{-33} (m_DM/GeV) cm^2 if the cross section is constant and a present-day value of sigma_{DM-neutrino} < 10^{-45} (m_DM/GeV) cm^2 if it scales as the temperature squared. These are the most robust limits on DM-neutrino interactions to date, demonstrating that one can use the distribution of matter in the Universe to probe dark ("invisible") interactions. Additionally, we show that scenarios involving thermal MeV DM and a constant elastic scattering cross section naturally predict (i) a cut-off in the matter power spectrum at the Lyman-alpha scale, (ii) N_eff ~ 3.5 +/- 0.4, (iii) H_0 ~ 71 +/- 3 km/s/Mpc and (iv) the possible generation of neutrino masses.Comment: 12 pages, 5 figure

Light spin-1/2 or spin-0 Dark Matter particles

We recall and precise how light spin-0 particles could be acceptable Dark Matter candidates, and extend this analysis to spin-1/2 particles. We evaluate the (rather large) annihilation cross sections required, and show how they may be induced by a new light neutral spin-1 boson U. If this one is vectorially coupled to matter particles, the (spin-1/2 or spin-0) Dark Matter annihilation cross section into e+e- automatically includes a v_dm^2 suppression factor at threshold, as desirable to avoid an excessive production of gamma rays from residual Dark Matter annihilations. We also relate Dark Matter annihilations with production cross sections in e+e- scatterings. Annihilation cross sections of spin-1/2 and spin-0 Dark Matter particles are given by exactly the same expressions. Just as for spin-0, light spin-1/2 Dark Matter particles annihilating into e+e- could be responsible for the bright 511 keV gamma ray line observed by INTEGRAL from the galactic bulge.Comment: 10 page