539 research outputs found
A new sap beetle (Coleoptera: Nitidulidae) to the United States with a revised key to the Camptodes Erichson occurring in America north of Mexico
A new beetle to the United States, Camptodes communis Erichson, is briefly described below. A diagnosis from the other Camptodes known to occur in the United States is provided. An updated key to the Camptodes of the United States is given
Revision of Pocadius Erichson (Coleoptera: Nitidulidae)
A revision of Pocadius Erichson (Coleoptera: Nitidulidae) was completed. A total of 46 species were (re)described, including 25 new species, a key to species constructed, and phylogenetic analysis performed. Taxonomic changes, including nomenclatural emendations, reinstatement of species, and description of new taxa, within this dissertation do not constitute formal changes as defined by the International Code of Zoological Nomenclature. Illustrations of the genitalia, key characters, and dorsal habitus of species are provided. The phylogeny demonstrates a monophyletic Pocadius. The phylogeny suggests a Palearctic origin of the genus with subsequent speciation into the Old World tropics and New World. Host specialization on gasteromycetes fungi by Pocadius species was shown not to be obligate but rather facultative. Some sympatric species were shown to have temporally disjunct occurrences that may provide reproductive isolation
Political Culture and Moral Literacy: Using Words to Create Better Workers
Integrity is commonly conflated with basic literacy in assessments of the skills workers need. This case study of a word-based character education program in Springfield, Missouri examines how business leaders may blame a lack of skills by employees on a lack of moral literacy. The premise of this essay is that the expression of a literacy program by participating institutions will be influenced by the political culture of the region in which the institutions reside. Considering the influence of political culture on community literacy programs is important because such influence is likely to privilege certain sets of socio-political and economic values, and ways of knowing, over others
Nonabelian dark matter: models and constraints
Numerous experimental anomalies hint at the existence of a dark matter (DM)
multiplet chi_i with small mass splittings. We survey the simplest such models
which arise from DM in the low representations of a new SU(2) gauge symmetry,
whose gauge bosons have a small mass mu < 1 GeV. We identify preferred
parameters M_chi ~ 1 TeV, mu ~ 100 MeV, alpha_g ~ 0.04 and the chi chi -> 4e
annihilation channel, for explaining PAMELA, Fermi, and INTEGRAL/SPI lepton
excesses, while remaining consistent with constraints from relic density,
diffuse gamma rays and the CMB. This consistency is strengthened if DM
annihilations occur mainly in subhalos, while excitations (relevant to the
excited DM proposal to explain the 511 keV excess) occur in the galactic center
(GC), due to higher velocity dispersions in the GC, induced by baryons. We
derive new constraints and predictions which are generic to these models.
Notably, decays of excited DM states chi' -> chi gamma arise at one loop and
could provide a new signal for INTEGRAL/SPI; big bang nucleosynthesis (BBN)
constraints on the density of dark SU(2) gauge bosons imply a lower bound on
the mixing parameter epsilon between the SU(2) gauge bosons and photon. These
considerations rule out the possibility of the gauge bosons that decay into
e^+e^- being long-lived. We study in detail models of doublet, triplet and
quintuplet DM, showing that both normal and inverted mass hierarchies can
occur, with mass splittings that can be parametrically smaller, e.g., O(100)
keV, than the generic MeV scale of splittings. A systematic treatment of Z_2
symmetry which insures the stability of the intermediate DM state is given for
cases with inverted mass hierarchy, of interest for boosting the 511 keV signal
from the excited dark matter mechanism.Comment: 28 pages, 17 figures; v2. added brief comment, reference
Metastable dark matter mechanisms for INTEGRAL 511 keV rays and DAMA/CoGeNT events
We explore dark matter mechanisms that can simultaneously explain the
galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual
modulation, and the excess of low-recoil dark matter candidates observed by
CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7
GeV mass range, with splittings respectively of order an MeV and a few keV. The
top two states have the small mass gap and transitions between them, either
exothermic or endothermic, can account for direct detections. Decays from one
of the top states to the ground state produce low-energy positrons in the
galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can
happen spontaneously, if the excited state is metastable (longer-lived than the
age of the universe), or it can be triggered by inelastic scattering of the
metastable states into the shorter-lived ones. We focus on a simple model where
the DM is a triplet of an SU(2) hidden sector gauge symmetry, broken at the
scale of a few GeV, giving masses of order \lsim 1 GeV to the dark gauge
bosons, which mix kinetically with the standard model hypercharge. The purely
decaying scenario can give the observed angular dependence of the 511 keV
signal with no positron diffusion, while the inelastic scattering mechanism
requires transport of the positrons over distances \sim 1 kpc before
annihilating. We note that an x-ray line of several keV in energy, due to
single-photon decays involving the top DM states, could provide an additional
component to the diffuse x-ray background. The model is testable by proposed
low-energy fixed target experiments.Comment: 27 pp, 19 figures; v2. minor clarification, added refs; v3. corrected
observed rate of positron production, added new section responding to
criticisms of arXiv:0904.1025; v4. corrected typos in eqs. (6) and (40
Predictions of the causal entropic principle for environmental conditions of the universe
The causal entropic principle has been proposed as a superior alternative to
the anthropic principle for understanding the magnitude of the cosmological
constant. In this approach, the probability to create observers is assumed to
be proportional to the entropy production \Delta S in a maximal causally
connected region -- the causal diamond. We improve on the original treatment by
better quantifying the entropy production due to stars, using an analytic model
for the star formation history which accurately accounts for changes in
cosmological parameters. We calculate the dependence of \Delta S on the density
contrast Q=\delta\rho/\rho, and find that our universe is much closer to the
most probable value of Q than in the usual anthropic approach and that
probabilities are relatively weakly dependent on this amplitude. In addition,
we make first estimates of the dependence of \Delta S on the baryon fraction
and overall matter abundance. Finally, we also explore the possibility that
decays of dark matter, suggested by various observed gamma ray excesses, might
produce a comparable amount of entropy to stars.Comment: RevTeX4, 13pp, 10 figures; v2. clarified introduction, added ref
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