Instability and Subsequent Evolution of Electroweak Bubbles

Bubbles in a first-order electroweak phase transition are nucleated with radii $R_0$ and expand with velocity $v$. If $v$ is subsonic, a bubble becomes unstable to non-spherical perturbations when its radius is roughly $10^4\, R_0$. These perturbations accelerate the transition, and the effective velocity of bubble growth rapidly becomes supersonic. The transition should subsequently proceed spherically via detonation. If for some reason the onset of detonation is postponed, the surface area of the bubbles may be enhanced by $10^5$. We discuss consequences for electroweak baryogenesis.Comment: 9 pages (IASSNS-HEP-92-46

Improved Landmine Discrimination With an Off-the-Shelf Metal Detector

While a lot of improvement has been achieved with metal detectors in detection depth and ground rejection, little effort has been directed toward better discrimination capabilities; high false-positive rates not only increase clearance time, they tend to lower deminer vigilance, causing accidents. The authors have modeled a statically operating, off-the-shelf metal detector by generating volumetric sensitivity profiles. They present in-laboratory measurements and results of experiments on a test demining site in Cambodia. This article aims at giving deminers a more informed view of metallic targets, allowing them to take differentiated actions during target identification and removal

Lessons Learned from Field Tests in Croatia and Cambodia

This article describes the development and the experiments performed with Gryphon, a new platform for tele-operated landmine detection. With Gryphon, the authors aim at reducing the gap between research and application by introducing partial autonomy in mine-detection operations with a robust platform. Tests have been performed in Croatia and Cambodia

Model-Independent Comparison of Direct vs. Indirect Detection of Supersymmetric Dark Matter

We compare the rate for elastic scattering of neutralinos from various nuclei with the flux of upward muons induced by energetic neutrinos from neutralino annihilation in the Sun and Earth. We consider both scalar and axial-vector interactions of neutralinos with nuclei. We find that the event rate in a kg of germanium is roughly equivalent to that in a $10^5$- to $10^7$-m$^2$ muon detector for a neutralino with primarily scalar coupling to nuclei. For an axially coupled neutralino, the event rate in a 50-gram hydrogen detector is roughly the same as that in a 10- to 500-m$^2$ muon detector. Expected experimental backgrounds favor forthcoming elastic-scattering detectors for scalar couplings while the neutrino detectors have the advantage for axial-vector couplings.Comment: 10 pages, self-unpacking uuencoded PostScript fil

An integrative contextual perspective on work intensification in professions

In dit artikel wordt onderzocht hoe maatschappelijke ontwikkelingen in de afgelopen 20 jaar gevolgen hebben gehad voor de werkintensivering van zes beroepen: thuiszorgmedewerker, leerkracht in het basisonderwijs, ICT-systeembeheerder, mobiele objectbeveiliger, vrachtwagenchauffeur binnenland en orderpicker. Om dit te kunnen doen, werd een integraal onderzoeksmodel ontwikkeld waarin werkin- tensivering wordt beschouwd vanuit de wisselwerking tussen vier aspecten: veranderingen in de kwanti- tatieve taakeisen, veranderingen in de kwalitatieve taakeisen, hulpbronnen in het werk en persoonlijke hulpbronnen van beroepsbeoefenaren. Vervolgens zijn drie focusgroepen georganiseerd met arbeids- deskundigen om deze vier aspecten in onderlinge samenhang te bespreken en in verband te brengen met contextuele factoren die het beroep in de loop der tijd hebben veranderd. Ook is gebruikgemaakt van het UWV-Claimbeoordelings- en Borgingssysteem (CBBS) om veranderingen in de functie-eisen te traceren in de zes beroepen sinds het jaar 2000

Indirect Detection of a Light Higgsino Motivated by Collider Data

Kane and Wells recently argued that collider data point to a Higgsino-like lightest supersymmetric partner which would explain the dark matter in our Galactic halo. They discuss direct detection of such dark-matter particles in laboratory detectors. Here, we argue that such a particle, if it is indeed the dark matter, might alternatively be accessible in experiments which search for energetic neutrinos from dark-matter annihilation in the Sun. We provide accurate analytic estimates for the rates which take into account all relevant physical effects. Currently, the predicted signal falls roughly one to three orders of magnitude below experimental bounds, depending on the mass and coupling of the particle; however, detectors such as MACRO, super-Kamiokande, and AMANDA will continue to take data and should be able to rule out or confirm an interesting portion of the possible mass range for such a dark-matter particle within the next five years.Comment: 10 pages, RevTe