8,316 research outputs found

    How a Non-hierarchical Neutrino Mass Matrix Can Arise

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    One puzzle of neutrino masses and mixings is that they do not exhibit the kind of strong "hierarchy" that is found for the quarks and charged leptons. Neutrino mass ratios and mixing angles are not small. A possible reason for this is proposed here. It is based on the fact that typical realistic grand unified models contain particles with unification-scale masses which, when integrated out, can yield a neutrino mass matrix that is not of the standard seesaw form.Comment: 12 pages, 5 figures, LaTe

    Reflecting on the technical development of the Mapping Sculpture project

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    This paper explains, evaluates and reflects on the technical challenges and opportunities that underpin both the Mapping Sculpture project and its mobile interface. It provides insights into the development process as an integral component of the research methodology, and highlights the importance of meaningful collaboration between researchers and software developers. Just as the project questions the conventional notion of the lone sculpture practitioner, so the technical development needed to mirror the complex web of connections between people, places, objects, organizations and events through enabling large-scale, distributed and collaborative research. Enabling access to these rich resources on mobile devices was a further innovative and challenging development, but one that opens up the possibility for fresh modes of access and development of new audiences. The success of this technical development offers a model for representing complex relationships hidden in multiple sources, enabling innovative research and enhancing access

    Inverse Hierarchy Approach to Fermion Masses

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    The first fermion family might play a special role in understanding the physics of flavour. This possibility is suggested by the observation that the up-down splitting within quark families increases with the family number: mumd m_u\sim m_d, mc>msm_c>m_s, mtmbm_t\gg m_b. We construct a model that realizes this feature of the spectrum in a natural way. The inter-family hierarchy is first generated by radiative phenomena in a sector of heavy isosinglet fermions and then transferred to quarks by means of a universal seesaw. A crucial role is played by left-right parity and up-down isotopic symmetry. No family symmetry is introduced. The model implies mu/md>m_u/m_d> 0.5 and the Cabibbo angle is forced to be md/ms\sim\sqrt{m_d/m_s}. The top quark is naturally in the 100 GeV range, but not too heavy: mt<m_t< 150 GeV. Inspired by the mass matrices obtained in the model for quarks, we suggest an ansatz also including charged leptons. The differences between uu-, dd- and ee-type fermions are simply parametrized by three complex coefficients \eps{u}, \eps{d} and \eps{e}. Additional consistent predictions are obtained: msm_s=100-150 MeV and mu/md<m_u/m_d< 0.75.Comment: 19 pages (standard TeX) + 1 table (cut out and LaTeX separately) + 1 figure (cut out and postscript separately); 2 additional figures available by fax upon request, LBL-32889, LMU-13/9

    Modelling yarn balloon motion in ring spinning

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    Air-drag on a ballooning yarn and balloon shape affect the yarn tension and ends-down (yarn breakage), which in turn affects energy consumption and yarn productivity in ring spinning. In this article, a mathematical model of yarn ballooning motion in ring spinning is established. The model can be used to generate balloon shape and predict tension in the ballooning yarn under given spinning conditions. Yarn tension was measured using a computer data acquisition system and the balloon shapes were captured using a digital camera with video capability during the experiments using cotton and wool yarns at various balloon-heights and with varying yarn-length in the balloon. The air-drag coefficients on ballooning cotton and wool yarns in ring spinning were estimated by making a &ldquo;best fit&rdquo; between the theoretical and experimental turning points. The theoretical results were verified with experimental data. The effects of air-drag and balloon shape on yarn tension are discussed

    Naturally Light Higgs Doublet in the Spinor Representation of SUSY SO(10)

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    Within the supersymmetric SO(10) GUT we explore the possibility of the light Higgs doublet being a member of the 16-dimensional spinorial representation. This fact is ultimately related with the assumption that the light matter (at least partially) resides in some of the tensor representations as well. Several interesting features emerge. First, provided that the same 16-plet is responsible for the breaking SO(10)SU(5)SO(10) \rightarrow SU(5), the heaviness of the top can automatically follow from the field content at MGUTM_{GUT}, without need of any flavour symmetries. Secondly, the doublet--triplet splitting problem receives a new natural solution. In addition, a dimension=5 (Higgsino mediated) proton decay can be naturally suppressed. We construct explicit SO(10) models with the above properties, with most general superpotentials under the symmetries.Comment: 13 pages, Late

    Culturally-appropriate, family- and community-based physical activity and healthy eating Intervention for african-american middle school-aged girls: A feasibility pilot

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    This study tested the feasibility and acceptability of a physical activity, healthy eating, and social support intervention. Twelve African-American daughter-mother dyads (BMI percentile: daughters=92.6±12.79; BMI: mothers=38.8±5.81 kg/m2) met weekly during the 8-week Intensive Phase; throughout the 6-month Maintenance Phase, participants received monthly newsletters for 3 months and attended monthly face-to-face sessions for 3 months. Daughters and mothers reported positive feedback about intervention activities and educational curriculum. Post-intervention daughter survey results revealed positive trends towards increasing PA; increasing breakfast, water, and fruit/vegetable intake; and reducing sugar sweetened drink consumption. Mothers reported similar behavioral changes. This unique intervention was highly enjoyed by participants and utilized feasible, family-involved strategies to address obesity-related behaviors among African-American females

    Controls on mangrove forest-atmosphere carbon dioxide exchanges in western Everglades National Park

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    We report on net ecosystem production (NEP) and key environmental controls on net ecosystem exchange (NEE) of carbon dioxide (CO2) between a mangrove forest and the atmosphere in the coastal Florida Everglades. An eddy covariance system deployed above the canopy was used to determine NEE during January 2004 through August 2005. Maximum daytime NEE ranged from −20 to −25 mmol (CO2) m−2 s−1 between March and May. Respiration (Rd) was highly variable (2.81 ± 2.41 mmol (CO2) m−2 s−1), reaching peak values during the summer wet season. During the winter dry season, forest CO2 assimilation increased with the proportion of diffuse solar irradiance in response to greater radiative transfer in the forest canopy. Surface water salinity and tidal activity were also important controls on NEE. Daily light use efficiency was reduced at high (\u3e34 parts per thousand (ppt)) compared to low (ppt) salinity by 46%. Tidal inundation lowered daytime Rd by ∼0.9 mmol (CO2) m−2 s−1 and nighttime Rd by ∼0.5 mmol (CO2) m−2 s−1. The forest was a sink for atmospheric CO2, with an annual NEP of 1170 ± 127 g C m−2 during 2004. This unusually high NEP was attributed to year‐round productivity and low ecosystem respiration which reached a maximum of only 3 g C m−2 d−1. Tidal export of dissolved inorganic carbon derived from belowground respiration likely lowered the estimates of mangrove forest respiration. These results suggest that carbon balance in mangrove coastal systems will change in response to variable salinity and inundation patterns, possibly resulting from secular sea level rise and climate change. Citation: Barr, J. G., V. Engel, J. D. Fuentes

    Analysis of Couplings with Large Tensor Representations in SO(2N) and Proton Decay

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    We develop techniques for the analysis of SO(2N) invariant couplings which allow a full exhibition of the SU(N) invariant content of the spinor and tensor representations. The technique utilizes a basis consisting of a specific set of reducible SU(N) tensors in terms of which the SO(2N) invariant couplings have a simple expansion. The technique is specially useful for couplings involving large tensor representations. We exhibit the technique by performing a complete determination of the trilinear couplings in the superpotential for the case of SO(10) involving the 16 plet of matter, i.e., we give a full determination of the 161610s{16-16-10_s}, 1616120a{16-16-120_a} and 1616126ˉs{16-16-\bar{126}_s} couplings. The possible role of large tensor representations in the generation of quark lepton textures is discussed. It is shown that the couplings involving 126ˉ\bar{126} dimensional representation generate extra zeros in the Higgs triplet textures which can lead to an enhancement of the proton decay lifetime by a factor of 10310^3. These results also have implications for neutrino mass textures.Comment: 14 pages, Latex: With the corrections of an Erratum included in the text of pape

    Archival ethics: The truth of the matter

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    This essay explores the question of whether records professionals are as aware of the ethical dimensions of their work as they should be. It consider first the historical and professional context of archival ethics, then examines a recent case about business archives involving the author that suggests the need for renewed attention to professional ethics, and concludes with a discussion about how archivists might reconsider the ethical dimensions of their work

    A primordial origin for the atmospheric methane of Saturn's moon Titan

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    The origin of Titan's atmospheric methane is a key issue for understanding the origin of the Saturnian satellite system. It has been proposed that serpentinization reactions in Titan's interior could lead to the formation of the observed methane. Meanwhile, alternative scenarios suggest that methane was incorporated in Titan's planetesimals before its formation. Here, we point out that serpentinization reactions in Titan's interior are not able to reproduce the deuterium over hydrogen (D/H) ratio observed at present in methane in its atmosphere, and would require a maximum D/H ratio in Titan's water ice 30% lower than the value likely acquired by the satellite during its formation, based on Cassini observations at Enceladus. Alternatively, production of methane in Titan's interior via radiolytic reactions with water can be envisaged but the associated production rates remain uncertain. On the other hand, a mechanism that easily explains the presence of large amounts of methane trapped in Titan in a way consistent with its measured atmospheric D/H ratio is its direct capture in the satellite's planetesimals at the time of their formation in the solar nebula. In this case, the mass of methane trapped in Titan's interior can be up to 1,300 times the current mass of atmospheric methane.Comment: Accepted for publication in Icaru
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