8,316 research outputs found
How a Non-hierarchical Neutrino Mass Matrix Can Arise
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
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
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: , , . 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 0.5 and the Cabibbo angle is forced
to be . The top quark is naturally in the 100 GeV range,
but not too heavy: 150 GeV. Inspired by the mass matrices obtained in
the model for quarks, we suggest an ansatz also including charged leptons. The
differences between -, - and -type fermions are simply parametrized by
three complex coefficients \eps{u}, \eps{d} and \eps{e}. Additional
consistent predictions are obtained: =100-150 MeV and 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
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 “best fit” 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)
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 , the heaviness of the
top can automatically follow from the field content at , 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
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
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
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 , and couplings. The
possible role of large tensor representations in the generation of quark lepton
textures is discussed. It is shown that the couplings involving
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
. 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
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
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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