568 research outputs found

    The crystalline units of the High Himalayas in the Lahul-Zanskar region (northwest India): metamorphic-tectonic history and geochronology of the collided and imbricated Indian plate

    Get PDF
    In the High Himalayan belt of northwest India, crustal thickening linked to Palaeogene collision between India and Eurasia has led to the formation of two main crystalline tectonic units separated by the syn-metamorphic Miyar Thrust: the High Himalayan Crystallines sensu stricto (HHC) at the bottom, and the Kade Unit at the top. These units are structurally interposed between the underlying Lesser Himalaya and the very low-grade sediments of the Tibetan nappes. They consist of paragneisses, orthogneisses, minor metabasics and, chiefly in the HHC, leucogranites. The HHC registers: a polyphase metamorphism with two main stages designated as M1 and M2; a metamorphic zonation with high-temperature recrystallization and migmatization at middle structural levels and medium-temperature assemblages at upper and lower levels. In contrast, the Kade Unit underwent a low-temperature metamorphism. Rb-Sr and U-Th-Pb isotope data point to derivation of the orthogneisses from early Palaeozoic granitoids, while the leucogranites formed by anatexis of the HHC rocks and were probably emplaced during Miocene time. Most of the complicated metamorphic setting is related to polyphase tectonic stacking of the HHC with the ‘cooler' Kade Unit and Lesser Himalaya during the Himalayan history. However, a few inconsistencies exist for a purely Himalayan age of some Ml assemblages of the HHC. As regards the crustal-derived leucogranites, the formation of a first generation mixed with quartzo-feldspathic leucosomes was possibly linked to melt-lubricated shear zones which favoured rapid crustal displacements; at upper levels they intruded during stage M2 and the latest movements along the syn-metamorphic Miyar Thrust, but before juxtaposition of the Tibetan nappes along the late- metamorphic Zanskar Faul

    Comparing the Performance of Hyperbolic and Circular Rod Quadrupole Mass Spectrometers with Applied Higher Order Auxiliary Excitation

    Get PDF
    This work applies higher order auxiliary excitation techniques to two types of quadrupole mass spectrometers (QMSs): commercial systems and spaceborne instruments. The operational settings of a circular rod geometry commercial system and an engineering test-bed for a hyperbolic rod geometry spaceborne instrument were matched, with the relative performance of each sensor characterized with and without applied excitation using isotopic measurements of Kr+. Each instrument was operated at the limit of the test electronics to determine the effect of auxiliary excitation on extending instrument capabilities. For the circular rod sensor, with applied excitation, a doubling of the mass resolution at 1% of peak transmission resulted from the elimination of the low-mass side peak tail typical of such rod geometries. The mass peak stability and ion rejection efficiency were also increased by factors of 2 and 10, respectively, with voltage scan lines passing through the center of stability islands formed from auxiliary excitation. Auxiliary excitation also resulted in factors of 6 and 2 in peak stability and ion rejection efficiency, respectively, for the hyperbolic rod sensor. These results not only have significant implications for the use of circular rod quadrupoles with applied excitation as a suitable replacement for traditional hyperbolic rod sensors, but also for extending the capabilities of existing hyperbolic rod QMSs for the next generation of spaceborne instruments and low-mass commercial systems

    Supersymmetry enhancement by monopole operators

    Get PDF
    We describe a method which allows one to study hidden symmetries in a large class of strongly coupled supersymmetric gauge theories in three dimensions. We apply this method to the ABJM theory and to the infrared limit of N=4 SQCD with adjoint and fundamental matter. We show that the U(N) ABJM model with Chern-Simons level k=1 or k=2 has hidden N=8 supersymmetry. Hidden supersymmetry is also shown to occur in N=4 d=3 SQCD with one fundamental and one adjoint hypermultiplet. The latter theory, as well as the U(N) ABJM theory at k=1, are shown to have a decoupled free sector. This provides evidence that both models are dual to the infrared limit of N=8 U(N) super-Yang-Mills theory.Comment: 29 pages, late

    Efficacy and toxicity of intravenous iron in a mouse model of critical care anemia

    Get PDF
    OBJECTIVE: Anemia is common in critically ill patients, due to inflammation and blood loss. Anemia can be associated with iron deficiency and low serum hepcidin levels. However, iron administration in this setting remains controversial because of its potential toxicity, including oxidative stress induction and sepsis facilitation. The objective of this work was to determine the efficacy and toxicity of iron administration using a mouse model mimicking critical care anemia as well as a model of acute septicemia. DESIGN: Prospective, randomized, open label controlled animal study. SETTING: University-based research laboratory. SUBJECTS: C57BL/6 and OF1 mice. INTERVENTIONS: Intraperitoneal injection of zymosan inducing generalized inflammation in C57BL/6 mice, followed in our full model by repeated phlebotomies. A dose equivalent to 15 mg/kg of ferric carboxymaltose was injected intravenously on day 5. To assess the toxicity of iron in a septicemia model, OF1 mice were simultaneously injected with iron and different Escherichia coli strains. MEASUREMENTS AND MAIN RESULTS: To investigate the effect of iron on oxidative stress, we measured reactive oxygen species production in the blood using luminol-amplified chemiluminescence and superoxide dismutase 2 messenger RNA levels in the liver. These markers of oxidative stress were increased after iron administration in control mice but not in zymosan-treated mice. Liver catalase messenger RNA levels decreased in iron-treated control mice. Iron administration was not associated with increased mortality in the septicemia model or in the generalized inflammation model. Iron increased hemoglobin levels in mice fed with a low iron diet and subjected to phlebotomies and zymosan 2 wks after treatment administration. CONCLUSIONS: Adverse effects of intravenous iron supplementation by ferric carboxymaltose seem to be minimal in our animal models. Furthermore, iron appears to be effective in correcting anemia, despite inflammation. Studies of efficacy and safety of iron in critically ill patients are warranted

    He bulge revealed: He and CO2 diurnal and seasonal variations in the upper atmosphere of Mars as detected by MAVEN NGIMS

    Full text link
    Analysis of the Neutral Gas and Ion Mass Spectrometer (NGIMS) on the Mars Atmosphere Volatiles and EvolutioN (MAVEN) spacecraft closed source data from all orbits with good pointing revealed an enhanced Helium [He] density on the nightside orbits and a depressed He density on the dayside by about a factor of 10–20. He was also found to be larger in the polar regions than in the equatorial regions. The northern polar winter nightside He bulge was approximately twice that of the northern polar summer nightside bulge. The first 6 weeks of the MAVEN prime mission had periapsis at high latitudes on the nightside during northern winter, followed by the midlatitudes on the dayside moving to low latitudes on the nightside returning to the high latitudes during northern summer. In this study we examined the NGIMS data not only in the different latitudes but sorted by solar longitude (Ls) in order to separate the diurnal or local solar time (LST) effects from the seasonal effects. The Mars Global Ionosphere‐Thermosphere Model (M‐GITM) has predicted the formation of a He bulge in the upper atmosphere of Mars on the nightside early morning hours (Ls = 2–5 h) with more He collecting around the poles. Taking a slice at constant altitude across all orbits indicates corresponding variations in He and CO2 with respect to LST and Ls and a diurnal and seasonal dependence.Key PointsData using MAVEN NGIMS for 1 Martian year reveal diurnal and seasonal variations in He and CO2 indicating a changing He bulge in upper atmosphereObserved He bulge is found to agree preliminarily with M‐GITM modeling effortsHe bulge found at Mars is similar to those found at Earth and VenusPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136361/1/jgra53312_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136361/2/jgra53312.pd

    Classification of N=6 superconformal theories of ABJM type

    Full text link
    Studying the supersymmetry enhancement mechanism of Aharony, Bergman, Jafferis and Maldacena, we find a simple condition on the gauge group generators for the matter fields. We analyze all possible compact Lie groups and their representations. The only allowed gauge groups leading to the manifest N=6 supersymmetry are, up to discrete quotients, SU(n) x U(1), Sp(n) x U(1), SU(n) x SU(n), and SU(n) x SU(m) x U(1) with possibly additional U(1)'s. Matter representations are restricted to be the (bi)fundamentals. As a byproduct we obtain another proof of the complete classification of the three algebras considered by Bagger and Lambert.Comment: 18 page

    Three-dimensional N=8 conformal supergravity and its coupling to BLG M2-branes

    Full text link
    This paper is concerned with the problem of coupling the N=8 superconformal Bagger-Lambert-Gustavsson (BLG) theory to N=8 conformal supergravity in three dimensions. We start by constructing the on-shell N=8 conformal supergravity in three dimensions consisting of a Chern-Simons type term for each of the gauge fields: the spin connection, the SO(8) R-symmetry gauge field and the spin 3/2 Rarita-Schwinger (gravitino) field. We then proceed to couple this theory to the BLG theory. The final theory should have the same physical content, i.e., degrees of freedom, as the ordinary BLG theory. We discuss briefly the properties of this "topologically gauged" BLG theory and why this theory may be useful.Comment: 20 pages, v2: references and comments added, presentation in section 3.2 extended. v3: misprints and a sign error corrected, version published in JHE

    Three-dimensional topologically gauged N=6 ABJM type theories

    Full text link
    In this paper we construct the N=6\mathcal N=6 conformal supergravity in three dimensions from a set of Chern-Simons-like terms one for each of the graviton, gravitino, and R-symmetry gauge field and then couple this theory to the N=6\mathcal N=6 superconformal ABJM theory. In a first step part of the coupled Lagrangian for this topologically gauged ABJM theory is derived by demanding that all terms of third and second order in covariant derivatives cancel in the supersymmtry variation of the Lagrangian. To achieve this the transformation rules of the two separate sectors must be augmented by new terms. In a second step we analyze all terms in δL\delta L that are of first order in covariant derivatives. The cancelation of these terms require additional terms in the transformation rules as well as a number of new terms in the Lagrangian. As a final step we check that all remaining terms in δL\delta L which are bilinear in fermions cancel which means that the presented Lagrangian and transformation rules constitute the complete answer. In particular we find in the last step new terms in the scalar potential containing either one or no structure constant. The non-derivative higher fermion terms in δL\delta L that have not yet been completely analyzed are briefly discussed.Comment: 26 pages, v.2 minor corrections, comment on relation to chiral gravity added

    Unifying N=5 and N=6

    Full text link
    We write the Lagrangian of the general N=5 three-dimensional superconformal Chern-Simons theory, based on a basic Lie superalgebra, in terms of our recently introduced N=5 three-algebras. These include N=6 and N=8 three-algebras as special cases. When we impose an antisymmetry condition on the triple product, the supersymmetry automatically enhances, and the N=5 Lagrangian reduces to that of the well known N=6 theory, including the ABJM and ABJ models.Comment: 19 pages. v2: Published version. Minor typos corrected, references adde

    Flavor brane on the baryonic branch of moduli space

    Full text link
    We study an extra flavor in the cascading SU((k+1)M)xSU(k M) gauge theory by adding probe D7-brane to the geometry. By finding a solution to the kappa-symmetry equation we establish that the D7-brane is mutually supersymmetric with the background everywhere on the baryonic branch of moduli space. We also discuss possible applications of this result.Comment: 15 pages; v2 typo corrected, references adde
    corecore