1,118 research outputs found
Soils and geologic investigation, Kamehame Ridge Subdivision, Oahu, Hawaii
W.O. 285-10, tax map key: 3-9-10: 7Sections: site conditions, field exploration, laboratory testing, geology and site conditions, recommendations, logs of test pits, field and laboratory specifications, earthwork specifications, general grading details, and site plan.Grant Company of Hawai
Preliminary soils investigation -- Makaua Subdivision, Kaaawa, Oahu, Hawaii
W.O. 312-10Sections: proposed development, site conditions, geology, field exploration, laboratory testing, soil conditions, recommendations, and limitations.William Hee and Associates, Inc
Improved analytical methods for microarray-based genome-composition analysis
BACKGROUND: Whereas genome sequencing has given us high-resolution pictures of many different species of bacteria, microarrays provide a means of obtaining information on genome composition for many strains of a given species. Genome-composition analysis using microarrays, or 'genomotyping', can be used to categorize genes into 'present' and 'divergent' categories based on the level of hybridization signal. This typically involves selecting a signal value that is used as a cutoff to discriminate present (high signal) and divergent (low signal) genes. Current methodology uses empirical determination of cutoffs for classification into these categories, but this methodology is subject to several problems that can result in the misclassification of many genes. RESULTS: We describe a method that depends on the shape of the signal-ratio distribution and does not require empirical determination of a cutoff. Moreover, the cutoff is determined on an array-to-array basis, accounting for variation in strain composition and hybridization quality. The algorithm also provides an estimate of the probability that any given gene is present, which provides a measure of confidence in the categorical assignments. CONCLUSIONS: Many genes previously classified as present using static methods are in fact divergent on the basis of microarray signal; this is corrected by our algorithm. We have reassigned hundreds of genes from previous genomotyping studies of Helicobacter pylori and Campylobacter jejuni strains, and expect that the algorithm should be widely applicable to genomotyping data
Graph Signal Restoration Using Nested Deep Algorithm Unrolling
Graph signal processing is a ubiquitous task in many applications such as
sensor, social, transportation and brain networks, point cloud processing, and
graph neural networks. Graph signals are often corrupted through sensing
processes, and need to be restored for the above applications. In this paper,
we propose two graph signal restoration methods based on deep algorithm
unrolling (DAU). First, we present a graph signal denoiser by unrolling
iterations of the alternating direction method of multiplier (ADMM). We then
propose a general restoration method for linear degradation by unrolling
iterations of Plug-and-Play ADMM (PnP-ADMM). In the second method, the unrolled
ADMM-based denoiser is incorporated as a submodule. Therefore, our restoration
method has a nested DAU structure. Thanks to DAU, parameters in the proposed
denoising/restoration methods are trainable in an end-to-end manner. Since the
proposed restoration methods are based on iterations of a (convex) optimization
algorithm, the method is interpretable and keeps the number of parameters small
because we only need to tune graph-independent regularization parameters. We
solve two main problems in existing graph signal restoration methods: 1)
limited performance of convex optimization algorithms due to fixed parameters
which are often determined manually. 2) large number of parameters of graph
neural networks that result in difficulty of training. Several experiments for
graph signal denoising and interpolation are performed on synthetic and
real-world data. The proposed methods show performance improvements to several
existing methods in terms of root mean squared error in both tasks
Quantifying Stock Price Response to Demand Fluctuations
We address the question of how stock prices respond to changes in demand. We
quantify the relations between price change over a time interval
and two different measures of demand fluctuations: (a) , defined as the
difference between the number of buyer-initiated and seller-initiated trades,
and (b) , defined as the difference in number of shares traded in buyer
and seller initiated trades. We find that the conditional expectations and of price change for a given or
are both concave. We find that large price fluctuations occur when demand is
very small --- a fact which is reminiscent of large fluctuations that occur at
critical points in spin systems, where the divergent nature of the response
function leads to large fluctuations.Comment: 4 pages (multicol fomat, revtex
Charge-based silicon quantum computer architectures using controlled single-ion implantation
We report a nanofabrication, control and measurement scheme for charge-based
silicon quantum computing which utilises a new technique of controlled single
ion implantation. Each qubit consists of two phosphorus dopant atoms ~50 nm
apart, one of which is singly ionized. The lowest two energy states of the
remaining electron form the logical states. Surface electrodes control the
qubit using voltage pulses and dual single electron transistors operating near
the quantum limit provide fast readout with spurious signal rejection. A low
energy (keV) ion beam is used to implant the phosphorus atoms in high-purity
Si. Single atom control during the implantation is achieved by monitoring
on-chip detector electrodes, integrated within the device structure, while
positional accuracy is provided by a nanomachined resist mask. We describe a
construction process for implanted single atom and atom cluster devices with
all components registered to better than 20 nm, together with electrical
characterisation of the readout circuitry. We also discuss universal one- and
two-qubit gate operations for this architecture, providing a possible path
towards quantum computing in silicon.Comment: 9 pages, 5 figure
Structural Properties of Self-Attracting Walks
Self-attracting walks (SATW) with attractive interaction u > 0 display a
swelling-collapse transition at a critical u_{\mathrm{c}} for dimensions d >=
2, analogous to the \Theta transition of polymers. We are interested in the
structure of the clusters generated by SATW below u_{\mathrm{c}} (swollen
walk), above u_{\mathrm{c}} (collapsed walk), and at u_{\mathrm{c}}, which can
be characterized by the fractal dimensions of the clusters d_{\mathrm{f}} and
their interface d_{\mathrm{I}}. Using scaling arguments and Monte Carlo
simulations, we find that for u<u_{\mathrm{c}}, the structures are in the
universality class of clusters generated by simple random walks. For
u>u_{\mathrm{c}}, the clusters are compact, i.e. d_{\mathrm{f}}=d and
d_{\mathrm{I}}=d-1. At u_{\mathrm{c}}, the SATW is in a new universality class.
The clusters are compact in both d=2 and d=3, but their interface is fractal:
d_{\mathrm{I}}=1.50\pm0.01 and 2.73\pm0.03 in d=2 and d=3, respectively. In
d=1, where the walk is collapsed for all u and no swelling-collapse transition
exists, we derive analytical expressions for the average number of visited
sites and the mean time to visit S sites.Comment: 15 pages, 8 postscript figures, submitted to Phys. Rev.
Effects of Pore Walls and Randomness on Phase Transitions in Porous Media
We study spin models within the mean field approximation to elucidate the
topology of the phase diagrams of systems modeling the liquid-vapor transition
and the separation of He--He mixtures in periodic porous media. These
topologies are found to be identical to those of the corresponding random field
and random anisotropy spin systems with a bimodal distribution of the
randomness. Our results suggest that the presence of walls (periodic or
otherwise) are a key factor determining the nature of the phase diagram in
porous media.Comment: REVTeX, 11 eps figures, to appear in Phys. Rev.
Scaling of the distribution of fluctuations of financial market indices
We study the distribution of fluctuations over a time scale (i.e.,
the returns) of the S&P 500 index by analyzing three distinct databases.
Database (i) contains approximately 1 million records sampled at 1 min
intervals for the 13-year period 1984-1996, database (ii) contains 8686 daily
records for the 35-year period 1962-1996, and database (iii) contains 852
monthly records for the 71-year period 1926-1996. We compute the probability
distributions of returns over a time scale , where varies
approximately over a factor of 10^4 - from 1 min up to more than 1 month. We
find that the distributions for 4 days (1560 mins) are
consistent with a power-law asymptotic behavior, characterized by an exponent
, well outside the stable L\'evy regime . To
test the robustness of the S&P result, we perform a parallel analysis on two
other financial market indices. Database (iv) contains 3560 daily records of
the NIKKEI index for the 14-year period 1984-97, and database (v) contains 4649
daily records of the Hang-Seng index for the 18-year period 1980-97. We find
estimates of consistent with those describing the distribution of S&P
500 daily-returns. One possible reason for the scaling of these distributions
is the long persistence of the autocorrelation function of the volatility. For
time scales longer than days, our results are
consistent with slow convergence to Gaussian behavior.Comment: 12 pages in multicol LaTeX format with 27 postscript figures
(Submitted to PRE May 20, 1999). See
http://polymer.bu.edu/~amaral/Professional.html for more of our work on this
are
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