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The development of forecast techniques for wave and surf conditions over the bars in the Columbia River Mouth and at the entrance to Yaquina Bay : final report
This investigation has been carried out primarily to define the Columbia
River bar crossing problem, to determine the physical factors involved in
hazardous transit developments, and to develop a method for predicting
hazardous bar transit conditions sufficiently in advance to allow proper
safety precautions to be effected.
Actual records of periods of bar closure for the years 1963 - 1969,
as determined by the Columbia River Bar Pilots Association, provide a firm
foundation for the entry into this study. Meteorological and oceanographic
conditions leading to the closures, as well as those occurring during
periods of closure, are being analyzed to identify the more immediate
causes for such situations and also to determine the nature of their temporal
and spatial evolution. Much of the background material necessary for this
study has been compiled, and case histories on conditions leading to closure
circumstances are being prepared to determine the various types of
situation development
Reionization and the abundance of galactic satellites
One of the main challenges facing standard hierarchical structure formation
models is that the predicted abundance of galactic subhalos with circular
velocities of 10-30 km/s is an order of magnitude higher than the number of
satellites actually observed within the Local Group. Using a simple model for
the formation and evolution of dark halos, based on the extended
Press-Schechter formalism and tested against N-body results, we show that the
theoretical predictions can be reconciled with observations if gas accretion in
low-mass halos is suppressed after the epoch of reionization. In this picture,
the observed dwarf satellites correspond to the small fraction of halos that
accreted substantial amounts of gas before reionization. The photoionization
mechanism naturally explains why the discrepancy between predicted halos and
observed satellites sets in at about 30 km/s, and for reasonable choices of the
reionization redshift (z_re = 5-12) the model can reproduce both the amplitude
and shape of the observed velocity function of galactic satellites. If this
explanation is correct, then typical bright galaxy halos contain many low-mass
dark matter subhalos. These might be detectable through their gravitational
lensing effects, through their influence on stellar disks, or as dwarf
satellites with very high mass-to-light ratios. This model also predicts a
diffuse stellar component produced by large numbers of tidally disrupted
dwarfs, perhaps sufficient to account for most of the Milky Way's stellar halo.Comment: 5 pages, 2 figures, Submitted to Ap
Current oscillations in Vanadium Dioxide: evidence for electrically triggered percolation avalanches
In this work, we experimentally and theoretically explore voltage controlled
oscillations occurring in micro-beams of vanadium dioxide. These oscillations
are a result of the reversible insulator to metal phase transition in vanadium
dioxide. Examining the structure of the observed oscillations in detail, we
propose a modified percolative-avalanche model which allows for
voltage-triggering. This model captures the periodicity and waveshape of the
oscillations as well as several other key features. Importantly, our modeling
shows that while temperature plays a critical role in the vanadium dioxide
phase transition, electrically induced heating cannot act as the primary
instigator of the oscillations in this configuration. This realization leads us
to identify electric field as the most likely candidate for driving the phase
transition
Aquatic biosurvey of the Lovell River on UNH land
We assessed the physical, chemical and biological conditions at two sites along the Lovell River on University of New Hampshire (UNH) -owned conservation land. The discharge was 4.4 m3 s-1 at Site 1 and 5.7 m3 s -1 downstream at Site 2. Canopy coverage ranged from 8-25%. Canopy was dominated by Eastern Hemlock (79-84%). Much of the stream was strewn with large boulders and the substrate consisted of rocks of highly variable sizes ( 3-549 cm dia.). Specific conductivity (22.1-23.3 µS), pH (6.4) and temperature (7.9-8.3 °C) varied little between sites. Macro-invertebrate bio-indices indicated either excellent water quality with no apparent organic pollution (3.0/10) or good water quality with possible slight organic pollution (4.4/10)
Screen Channel Liquid Acquisition Device Outflow Tests in Liquid Hydrogen
This paper presents experimental design and test results of the recently concluded 1-g inverted vertical outflow testing of two 325x2300 full scale liquid acquisition device (LAD) channels in liquid hydrogen (LH2). One of the channels had a perforated plate and internal cooling from a thermodynamic vent system (TVS) to enhance performance. The LADs were mounted in a tank to simulate 1-g outflow over a wide range of LH2 temperatures (20.3 - 24.2 K), pressures (100 - 350 kPa), and flow rates (0.010 - 0.055 kg/s). Results indicate that the breakdown point is dominated by liquid temperature, with a second order dependence on mass flow rate through the LAD. The best performance is always achieved in the coldest liquid states for both channels, consistent with bubble point theory. Higher flow rates cause the standard channel to break down relatively earlier than the TVS cooled channel. Both the internal TVS heat exchanger and subcooling the liquid in the propellant tank are shown to significantly improve LAD performance
Mode effects between computer self-administration and telephone interviewer-administration of the PROMIS® pediatric measures, self- and proxy report
To test equivalence of scores obtained with the PROMIS® pediatric Depressive Symptoms, Fatigue, and Mobility measures across two modes of administration: computer self-administration and telephone interviewer-administration. If mode effects are found, to estimate the magnitude and direction of the mode effects
Fish Colonization of a Newly Deployed Vessel-reef off Southeast Florida: Preliminary Results
Fish colonization on the Ebenezer II, a 25.5m merchant marine vessel, was studied from May 2002 - July 2003. The ship was scuttled in May 2002 off Broward County, Florida at a depth of 21m and was censused 10 times during the study period using a modified Bohnsack and Bannerot visual census method. Adjacent natural reefs and the Mcallister, a nearby, 30m tugboat deployed in June 1998, were censused during the same period.
Distinct changes in the fish assemblage on the Ebenezer II were observed throughout the sample period. A pioneer assemblage was observed during the first three months, characterized by the settlement of juvenile fishes «5 cm). Subsequently, numbers of juveniles decreased either through emigration, predation or growth. Resident species made up 52.5% of the total abundance but transient fish species made up 78% of the total fish biomass during the study period.
Surprisingly, attraction of adult fish from both natural reefs and the Mcallister was not a major factor in assemblage fonnation. The primary adult fishes attracted to the Ebenezer II were herbivores. These fishes steadily increased in abundance throughout the study period, presumably due to increased food availability as benthic algal communities developed. A similar trend of increasing herbivores with increasing soak time was observed on the Spiegel Grove, a 153m vessel-reef sunk off Key Largo in May 2002.
The fish assemblages on the artificial reefs were more similar to each other than to natural reefs. Vessel-reefs had sixty species in common, while the Ebenezer II only had thirty-nine species in common with natural reefs. Several species common to vessel-reefs were absent or rare on nearby natural reefs. This may indicate that vessel-reefs are providing early juvenile and adult habitat that is not available on natural reefs
Getting beta-alpha without penguins
Oscillation effects in B0 -> Ks D0 and related processes are considered to
determine delta=beta-alpha+pi. We suggest that D0 decays to CP eigenstates used
in concert with inclusive D0 decays provide a powerful method for determining
delta cleanly i.e. without any complication from penguin processes. The CP
asymmetry is expected to be <=40% for D0 decays to non-CP eigenstates and <=80%
for decays to CP eigenstates. This method can lead to a fairly accurate
determination of delta with O(10^8-10^9) B-mesons.Comment: 4 pages 1 figure; Version 2: minor changes; references added; Some
changes in response to Referee Comment
Modeling Kepler transit light curves as false positives: Rejection of blend scenarios for Kepler-9, and validation of Kepler-9d, a super-Earth-size planet in a multiple system
Light curves from the Kepler Mission contain valuable information on the
nature of the phenomena producing the transit-like signals. To assist in
exploring the possibility that they are due to an astrophysical false positive,
we describe a procedure (BLENDER) to model the photometry in terms of a "blend"
rather than a planet orbiting a star. A blend may consist of a background or
foreground eclipsing binary (or star-planet pair) whose eclipses are attenuated
by the light of the candidate and possibly other stars within the photometric
aperture. We apply BLENDER to the case of Kepler-9, a target harboring two
previously confirmed Saturn-size planets (Kepler-9b and Kepler-9c) showing
transit timing variations, and an additional shallower signal with a 1.59-day
period suggesting the presence of a super-Earth-size planet. Using BLENDER
together with constraints from other follow-up observations we are able to rule
out all blends for the two deeper signals, and provide independent validation
of their planetary nature. For the shallower signal we rule out a large
fraction of the false positives that might mimic the transits. The false alarm
rate for remaining blends depends in part (and inversely) on the unknown
frequency of small-size planets. Based on several realistic estimates of this
frequency we conclude with very high confidence that this small signal is due
to a super-Earth-size planet (Kepler-9d) in a multiple system, rather than a
false positive. The radius is determined to be 1.64 (+0.19/-0.14) R(Earth), and
current spectroscopic observations are as yet insufficient to establish its
mass.Comment: 20 pages in emulateapj format, including 8 tables and 16 figures. To
appear in ApJ, 1 January 2010. Accepted versio
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