55,648 research outputs found
Anomalies, Chern-Simons Terms and Chiral Delocalization in Extra Dimensions
Gauge invariant topological interactions, such as the D=5 Chern-Simons terms,
are required in models in extra dimensions that split anomaly free
representations. The Chern-Simons term is necessary to maintain the overall
anomaly cancellations of the theory, but it can have significant, observable,
physical effects. The CS-term locks the KK-mode parity to the parity of
space-time, leaving a single parity symmetry. It leads to new processes amongst
KK-modes, eg, the decay of a KK-mode to a 2-body final state of KK-modes. A
formalism for the effective interaction amongst KK-modes is constructed, and
the decay of a KK-mode to KK-mode plus zero mode is analyzed as an example. We
elaborate the general KK-mode current and anomaly structure of these theories.
This includes a detailed study of the triangle diagrams and the associated
``consistent anomalies'' for Weyl spinors on the boundary branes. We also
develop the non-abelian formalism. We illustrate this by showing in a simple
way how a D=5 Yang-Mills ``quark flavor'' symmetry leads to the D=4 chiral
lagrangian of mesons and the quantized Wess-Zumino-Witten term.Comment: 51 pages, 3 figures; Corrected typos, amplified discussio
Sedimentation in an artificial lake -Lake Matahina, Bay of Plenty
Lake Matahina, an 8 km long hydroelectric storage reservoir, is a small (2.5 km2), 50 m deep, warm monomictic, gorge-type lake whose internal circulation is controlled by the inflowing Rangitaiki River which drains a greywacke and acid volcanic catchment. Three major proximal to distal subenvironments are defined for the lake on the basis of surficial sediment character and dominant depositional process: (a) fluvial-glassy, quartzofeld-spathic, and lithic gravel-sand mixtures deposited from contact and saltation loads in less than 3 m depth; (b) (pro-)deltaic-quartzofeldspathic and glassy sand-silt mixtures deposited from graded and uniform suspension loads in 3-20 m depth; and (c) basinal-diatomaceous, argillaceous, and glassy silt-clay mixtures deposited from uniform and pelagic suspension loads in 20-50 m depth. The delta face has been prograding into the lake at a rate of 35-40 m/year and vertical accretion rates in pro-delta areas are 15-20 cm/year. Basinal deposits are fed mainly from river plume dispersion involving overflows, interflows, and underflows, and by pelagic settling, and sedimentation rates behind the dam have averaged about 2 cm/year. Occasional fine sand layers in muds of basinal cores attest to density currents or underflows generated during river flooding flowing the length of the lake along a sublacustrine channel marking the position of the now submerged channel of the Rangitaiki River
Structural and dynamical uncertainties in modeling axisymmetric elliptical galaxies
Quantitative dynamical models of galaxies require deprojecting the observed
surface brightness to determine the luminosity density of the galaxy. Existing
deprojection methods for axisymmetric galaxies assume that a unique
deprojection exists for any given inclination, even though the projected
density is known to be degenerate to the addition of "konus densities" that are
invisible in projection. We develop a deprojection method based on linear
regularization that can explore the range of luminosity densities statistically
consistent with an observed surface brightness distribution. The luminosity
density is poorly constrained at modest inclinations (i > ~30 deg), even in the
limit of vanishing observational errors. In constant mass-to-light ratio,
axisymmetric, two-integral dynamical models, the uncertainties in the
luminosity density result in large uncertainties in the meridional plane
velocities. However, the projected line-of-sight velocities show variations
comparable to current typical observational uncertainties.Comment: 20 pages, 8 Postscript figures, LaTeX, aaspp4.sty, submitted to
MNRAS; paper w/figs (600 kb) also available at
http://cfa-www.harvard.edu/~romanow/ell.mn.ps.gz GIF-format figures replaced
by PostScrip
The State of the Art in Performance Management: Learnings from Discussions with Leading Organizations
Performance management is one of the fundamental HR tools that has been part of organizational life for decades and has long been the backbone of other activities of the HR system (e.g., pay decisions, development plans). Despite the importance of performance management, it has historically been rated by employees, managers, and the HR function itself as one of the least effective and understood HR practices. Given the stagnation in academic research on the topic and discontent on the part of organizational stakeholders, we decided it was an opportune time to meet with leading companies to understand the state of the art in performance management. Specifically, we held two working group meetings with a total of 32 HR executives from 20 companies to discuss current challenges and best practices in the area of performance management. The discussions provided us with a deeper understanding of the dilemmas and challenges associated with performance management in large, multinational companies. We were also able to extract a handful of promising directions for enhancing the effectiveness of the performance management process
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An Exploration of Spotted White Dwarfs from K2
The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018The Kepler K2 mission has discovered a significant
population of white dwarf stars that exhibit
photometric variability due to surface inhomogeneities
likely related to magnetism. These âspottedâ
white dwarfs present not only in temperature
regimes where we expect convection to dominate
white dwarf photospheres, but also where
radiation should dominate. We present an exploration
of spotted white dwarfs as a function of
various physical characteristics, including temperature,
magnetic field strength, and rotational period,
in order to better understand the origins of
these photometric variations.Astronom
Galaxy Aggregates in the Coma Cluster
We present evidence for a new morphologically defined form of small-scale
substructure in the Coma Cluster, which we call galaxy aggregates. These
aggregates are dominated by a central galaxy, which is on average three
magnitudes brighter than the smaller aggregate members nearly all of which lie
to one side of the central galaxy. We have found three such galaxy aggregates
dominated by the S0 galaxies RB 55, RB 60, and the star-bursting SBb, NGC 4858.
RB 55 and RB 60 are both equi-distant between the two dominate D galaxies NGC
4874 and NGC 4889, while NGC 4858 is located next to the larger E0 galaxy NGC
4860. All three central galaxies have redshifts consistant with Coma Cluster
membership. We describe the spatial structures of these unique objects and
suggest several possible mechanisms to explain their origin. These include:
chance superpositions from background galaxies, interactions between other
galaxies and with the cluster gravitational potential, and ram pressure. We
conclude that the most probable scenario of creation is an interaction with the
cluster through its potential.Comment: Ten Pages with six figures; submitted to MNRAS letter
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