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Groundwater maps of the Hanford Site, December 1994
This report is a continuation of a series of reports (see Serkowski et al 1994) that the configuration of the uppermost unconfined aquifer beneath the Hanford Site. This series presents the results of the semiannual water level measurement program and the water table maps generated from these measurements. The reports document the changes in the groundwater level at the Hanford Site during the transition from nuclear material production to environmental restoration and remediation. In addition, these reports provide water level data to support the various site characterization and groundwater monitoring programs currently in progress on the Hanford Site
The STACEE-32 Ground Based Gamma-ray Detector
We describe the design and performance of the Solar Tower Atmospheric
Cherenkov Effect Experiment detector in its initial configuration (STACEE-32).
STACEE is a new ground-based gamma ray detector using the atmospheric Cherenkov
technique. In STACEE, the heliostats of a solar energy research array are used
to collect and focus the Cherenkov photons produced in gamma-ray induced air
showers. The large Cherenkov photon collection area of STACEE results in a
gamma-ray energy threshold below that of previous detectors.Comment: 45 pages, 25 figures, Accepted for publication in Nuclear Instruments
and Methods
Ultra-fast propagation of Schr\"odinger waves in absorbing media
We identify the characteristic times of the evolution of a quantum wave
generated by a point source with a sharp onset in an absorbing medium. The
"traversal'' or "B\"uttiker-Landauer'' time (which grows linearly with the
distance to the source) for the Hermitian, non-absorbing case is substituted by
three different characteristic quantities. One of them describes the arrival of
a maximum of the density calculated with respect to position, but the maximum
with respect to time for a given position becomes independent of the distance
to the source and is given by the particle's ``survival time'' in the medium.
This later effect, unlike the Hartman effect, occurs for injection frequencies
under or above the cut-off, and for arbitrarily large distances. A possible
physical realization is proposed by illuminating a two-level atom with a
detuned laser
Generalized Jacobi identities and ball-box theorem for horizontally regular vector fields
We consider a family of vector fields and we assume a horizontal regularity
on their derivatives. We discuss the notion of commutator showing that
different definitions agree. We apply our results to the proof of a ball-box
theorem and Poincar\'e inequality for nonsmooth H\"ormander vector fields.Comment: arXiv admin note: material from arXiv:1106.2410v1, now three separate
articles arXiv:1106.2410v2, arXiv:1201.5228, arXiv:1201.520
MeV-mass dark matter and primordial nucleosynthesis
The annihilation of new dark matter candidates with masses in the MeV
range may account for the galactic positrons that are required to explain the
511 keV -ray flux from the galactic bulge. We study the impact of
MeV-mass thermal relic particles on the primordial synthesis of H, He,
and Li. If the new particles are in thermal equilibrium with neutrinos
during the nucleosynthesis epoch they increase the helium mass fraction for
m_X\alt 10 MeV and are thus disfavored. If they couple primarily to the
electromagnetic plasma they can have the opposite effect of lowering both
helium and deuterium. For --10 MeV they can even improve the overall
agreement between the predicted and observed H and He abundances.Comment: 11 pages, 10 figures, references and two appendices added,
conclusions unchanged; accepted for publication in Phys.Rev.
A first EGRET-UNID-related agenda for the next-generation Cherenkov telescopes
The next generation of Imaging Atmospheric Cherenkov Telescopes (IACTs) will
open the regime between approx. 30 GeV and 200 GeV to ground-based gamma
observations with unprecedented point source sensitivity and source location
accuracy. I examine the prospects of observing the unidentified objects (UNIDs)
of the Third EGRET Catalog using the IACT observatories currently under
construction by the CANGAROO, HESS, MAGIC and VERITAS collaborations. Assuming
a modest spectral steepening similar to that observed in the inverse Compton
component of the Crab Nebula spectrum and taking into account the sensitivity
of the instruments and its zenith angle dependence, a detailed list of 78
observable objects is derived which is then further constrained to 38 prime
candidates. The characteristics of this agenda are discussed.Comment: 21 pages, 5 figures, to be published in Carraminana, Reimer &
Thompson (eds.) Proc. "The nature of unidentified high-energy gamma-ray
sources (Tonantzintla, Mexico, October 2000)", Kluwer Academi
Modeling the Emission Processes in Blazars
Blazars are the most violent steady/recurrent sources of high-energy
gamma-ray emission in the known Universe. They are prominent emitters of
electromagnetic radiation throughout the entire electromagnetic spectrum. The
observable radiation most likely originates in a relativistic jet oriented at a
small angle with respect to the line of sight. This review starts out with a
general overview of the phenomenology of blazars, including results from a
recent multiwavelength observing campaign on 3C279. Subsequently, issues of
modeling broadband spectra will be discussed. Spectral information alone is not
sufficient to distinguish between competing models and to constrain essential
parameters, in particular related to the primary particle acceleration and
radiation mechanisms in the jet. Short-term spectral variability information
may help to break such model degeneracies, which will require snap-shot
spectral information on intraday time scales, which may soon be achievable for
many blazars even in the gamma-ray regime with the upcoming GLAST mission and
current advances in Atmospheric Cherenkov Telescope technology. In addition to
pure leptonic and hadronic models of gamma-ray emission from blazars,
leptonic/hadronic hybrid models are reviewed, and the recently developed
hadronic synchrotron mirror model for TeV gamma-ray flares which are not
accompanied by simultaneous X-ray flares (``orphan TeV flares'') is revisited.Comment: Invited Review at "The Multimessenger Approach to Gamma-Ray Sources",
Barcelona, Spain, July 2006; submitted to Astrophysics and Space Science. 10
pages, including 6 eps figures. Uses Springer's ApSS macro
On the Recognition of Four-Directional Orthogonal Ray Graphs
Orthogonal ray graphs are the intersection graphs of horizontal and vertical rays (i.e. half-lines) in the plane. If the rays can have any possible orientation (left/right/up/down) then the graph is a 4-directional orthogonal ray graph (4-DORG). Otherwise, if all rays are only pointing into the positive x and y directions, the intersection graph is a 2-DORG. Similarly, for 3-DORGs, the horizontal rays can have any direction but the vertical ones can only have the positive direction. The recognition problem of 2-DORGs, which are a nice subclass of bipartite comparability graphs, is known to be polynomial, while the recognition problems for 3-DORGs and 4-DORGs are open. Recently it has been shown that the recognition of unit grid intersection graphs, a superclass of 4-DORGs, is NP-complete. In this paper we prove that the recognition problem of 4-DORGs is polynomial, given a partition {L,R,U,D} of the vertices of G (which corresponds to the four possible ray directions). For the proof, given the graph G, we first construct two cliques G 1,G 2 with both directed and undirected edges. Then we successively augment these two graphs, constructing eventually a graph TeX with both directed and undirected edges, such that G has a 4-DORG representation if and only if TeX has a transitive orientation respecting its directed edges. As a crucial tool for our analysis we introduce the notion of an S-orientation of a graph, which extends the notion of a transitive orientation. We expect that our proof ideas will be useful also in other situations. Using an independent approach we show that, given a permutation π of the vertices of U (π is the order of y-coordinates of ray endpoints for U), while the partition {L,R} of V ∖ U is not given, we can still efficiently check whether G has a 3-DORG representation
Towards a population of HMXB/NS microquasars as counterparts of low-latitude unidentified EGRET sources
The discovery of the microquasar LS 5039 well within the 95% conficence
contour of the Unidentified EGRET Source (UES) 3EG J1824-1514 was a major step
towards the possible association between microquasars (MQs) and UESs. The
recent discovery of precessing relativistic radio jets in LS I +61 303, a
source associated for long time with 2CG 135+01 and with the UES 3EG
J0241+6103, has given further support to this idea. Finally, the very recently
proposed association between the microquasar candidate AX J1639.0-4642 and the
UES 3EG J1639-4702 points towards a population of High Mass X-ray Binary
(HMXB)/Neutron Star (NS) microquasars as counterparts of low-latitude
unidentified EGRET sources.Comment: 12 pages, 7 figures. Proceedings of the Conference "The
Multiwavelength Approach to Unidentified Gamma-ray Sources", to appear in the
journal Astrophysics and Space Scienc
"MOODY BLUES": Affect Interpretation of Infant Facial Expressions and Negative Affect in Mothers of Preterm and Term Infants
Preterm birth places infants at increased risk for adverse developmental outcomes, with self- and affect regulation problems among the most important impairments. However, few studies have empirically examined maternal interpretation of infant affect in mothers of pre- and term infants. The current study examines how negative affect of mothers of preterm and term infants is associated with their interpretation of infant facial expressions.One hundred and sixty-eight mothers with their infants (64 term and 104 preterm) participated. Seven days after birth, mothers completed the UWIST Mood Adjective Checklist (UMACL; Matthews, Jones, & Chamberlain, 1990) to assess maternal negative affect. During a home visit, six months after birth, mothers additionally completed a task developed to measure infant affect interpretation (Interpreting Facial Expressions of Emotions through Looking at Pictures task, IFEEL pictures task; Emde, Osofsky, & Butterfield, 1993).Mothers of preterm infants reported more negative affect than mothers of term infants. However, the relationship between infant birth status (i.e., term vs. preterm) and maternal interpretation of infant facial expressions was moderated by the mother\u27s own negative affectivity. Surprisingly, particularly mothers of term infants who also reported high levels of negative affect were found to interpret infant affect significantly more negatively.Prematurity itself does not seem to be a dominant factor in determining maternal infant affect interpretation, though maternal psychological negative mood does. Both theoretical and practical implications of the results are discussed
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