Energy Loss from a Moving Vortex in Superfluid Helium

We present measurements on both energy loss and pinning for a vortex terminating on the curved surface of a cylindrical container. We vary surface roughness, cell diameter, fluid velocity, and temperature. Although energy loss and pinning both arise from interactions between the vortex and the surface, their dependences on the experimental parameters differ, suggesting that different mechanisms govern the two effects. We propose that the energy loss stems from reconnections with a mesh of microscopic vortices that covers the cell wall, while pinning is dominated by other influences such as the local fluid velocity.Comment: 8 pages, 6 figure

Non-unique factorization of polynomials over residue class rings of the integers

We investigate non-unique factorization of polynomials in Z_{p^n}[x] into irreducibles. As a Noetherian ring whose zero-divisors are contained in the Jacobson radical, Z_{p^n}[x] is atomic. We reduce the question of factoring arbitrary non-zero polynomials into irreducibles to the problem of factoring monic polynomials into monic irreducibles. The multiplicative monoid of monic polynomials of Z_{p^n}[x] is a direct sum of monoids corresponding to irreducible polynomials in Z_p[x], and we show that each of these monoids has infinite elasticity. Moreover, for every positive integer m, there exists in each of these monoids a product of 2 irreducibles that can also be represented as a product of m irreducibles.Comment: 11 page

The Impact of Social Movements on Austerity Measures: An Analysis of Argentina’s Piquetero Movement and Greece’s Anti-Austerity Movement

Social movements have sprung up in countries after their respective economies experience an economic crisis and the International Monetary Fund places restrictions on a country’s fiscal policy. Argentina’s piquetero movement and Greece’s anti-austerity movement have both mobilized after economic crises to protest the neoliberal shifts to their economics, yet their success at shifting those policies have not been studied sufficiently. The dominant explanation for social movement success involves analyzing political opportunities or seeing the social movement as an actor with limited resources. These existent methods fail to answer how nuances about internal decisions or forms of protest could influence the outcomes of the movements. I use Argentina’s and Greece’s social movements as case studies and analyzed them through a new framework: (1) forms of protest, (2) relationship to government, and (3) locus of decision making. In this analysis, I conclude that social movements have not been successful in reversing IMF restrictions, but they are successful in shifting the national political scene or culture. This research demonstrates that social movements are best equipped to influence local communities or national politics, but are limited in their impact on international pressures

Mantle heterogeneity during the formation of the North Atlantic Igneous Province: Constraints from trace element and Sr-Nd-Os-O isotope systematics of Baffin Island picrites

Sr-Nd-Os-O isotope and major and trace element data from ~62 Ma picrites from Baffin Island constrain the composition of mantle sources sampled at the inception of North Atlantic Igneous Province (NAIP) magmatism. We recognize two compositional types. Depleted (N-type) lavas have low 87Sr/86Sri (0.702990–0.703060) and 187Os/188Osi (0.1220–0.1247) and high 143Nd/144Ndi (0.512989–0.512999) and are depleted in incompatible elements relative to primitive mantle. Enriched (E-type) lavas have higher 87Sr/86Sri (0.703306–0.703851) and 187Os/188Osi (0.1261–0.1303), lower 143Nd/144Ndi (0.512825–0.512906), and incompatible element concentrations similar to, or more enriched than, primitive mantle. There is also a subtle difference in oxygen isotope composition; E-type lavas are marginally lower in δ18Oolivine value (5.16–4.84‰) than N-type lavas (5.15–5.22‰). Chemical and isotopic variations between E- and N-type lavas are inconsistent with assimilation of crust and/or subcontinental lithospheric mantle and appear to instead reflect mixing between melts derived from two distinct mantle sources. Strontium-Nd-O isotope compositions and incompatible trace element abundances of N-type lavas suggest these are largely derived from the depleted upper mantle. The 187Os/188Osi ratios of N-type lavas can also be explained by such a model but require that the depleted upper mantle had γOs of approximately −5 to −7 at 62 Ma. This range overlaps the lowest γOs values measured in abyssal peridotites. Baffin Island lava compositions are also permissive of a model involving recharging of depleted upper mantle with 3He-rich material from the lower mantle (Stuart et al., Nature, 424, 57–59, 2003), with the proviso that recharge had no recognizable effect on the lithophile trace element and Sr-Nd-Os-O isotope composition. The origin of the enriched mantle component sampled by Baffin Island lavas is less clear but may be metasomatized and high-temperature-altered recycled oceanic lithosphere transported within the proto Iceland plume. Differences between Baffin Island lavas and modern Icelandic basalts suggest that a range of enriched and depleted mantle sources have been tapped since the inception of magmatism in the province. Similarities between Baffin Island lavas erupted and those of similar age from East and West Greenland also suggest that the enriched component in Baffin Island lavas may have been sampled by lavas erupted over a wide geographic range

Tabakkonsum bei Erwachsenen mit ADHS

Zusammenfassung: Hintergrund: Untersuchungen aus den USA wiesen Zusammenhänge zwischen der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) und dem Rauchen nach. Bis heute wurden in der Schweiz keine vergleichbaren Studien durchgeführt. Ziel der vorliegenden Arbeit war es, neue Erkenntnisse über die Beziehung der ADHS und dem Tabakkonsum bei erwachsenen ADHS-Patienten aus der Schweiz zu gewinnen. Material und Methoden: Eine schriftliche Befragung zum Tabakkonsum erfolgte bei allen erwachsenen Patienten mit einer ADHS-Diagnose gemäß DSM-IV, die von September 2000 bis Januar 2006 ambulant im Rahmen der Spezialsprechstunde für ADHS der Psychiatrischen Universitätsklinik Zürich behandelt wurden. 100 der 134Patienten konnten in die Studie eingeschlossen werden. Ergebnisse: Der Raucheranteil in der ADHS-Stichprobe lag mit 55% signifikant über dem Raucheranteil in der Schweizer Wohnbevölkerung (31%). Zudem wiesen täglich rauchende ADHS-Patienten eine höhere Konsummenge und stärkere Nikotinabhängigkeit auf und haben früher begonnen, regelmäßig zu rauchen. Ihre Aufhörbereitschaft war hoch und vergleichbar mit Rauchenden aus der Schweizer Wohnbevölkerung. Schlussfolgerungen: Die Resultate dieser Schweizer Studie sind konsistent mit Befunden aus den USA. Viele ADHS-Patienten sind zum Rauchstopp motiviert und sollten in Abhängigkeit ihrer Aufhörmotivation eine Beratung zum Rauchstopp erhalte

Mitralklappenendokarditis nach türkischem Opferfest

Zusammenfassung: Erysipelothrix rhusiopathiae ist der Erreger des Schweinerotlaufs. Systemische Infektionen durch E.rhusiopathiae sind eine Rarität, jedoch häufig (zu 90%) mit Endokarditiden verbunden. Ungefähr 60% der Endokarditiden entwickeln sich auf nicht vorgeschädigten Klappen, und trotz adäquater antibiotischer Therapie benötigen etwa ein Drittel der Patienten einen Klappenersatz. Wir beschreiben den Fall einer Hausfrau, die nach Zubereitung von Fleisch für das türkische Opferfest eine Mitralklappenendokarditis durch E.rhusiopathiae entwickelt

Analysis and correction of the magnetic field effects in the Hybrid Photo-Detectors of the RICH2 Ring Imaging Cherenkov detector of LHCb

The Ring Imaging Cherenkov detectors of the LHCb experiment at the Large Hadron Collider at CERN are equipped with Hybrid Photo-Detectors. These vacuum photo-detectors are affected by the stray magnetic field of the LHCb magnet, which degrades their imaging properties. This effect increases the error on the Cherenkov angle measurement and would reduce the particle identification capabilities of LHCb. A system has been developed for the RICH2 Ring Imaging Cherenkov detector to perform a detailed characterisation of the magnetic distortion effects. It is described, along with the methods implemented to correct for these effects, restoring the optimal resolution.Comment: 16 pages, 11 figure