722 research outputs found
(Re)constructing Homescapes: âArchaeological remote sensingâ and ground-truthing of the Walker Place homestead at Spirit Hill Farm, Tate County, Mississippi
This thesis focuses on an early nineteenth-century homestead known as the Walker Place homestead at Spirit Hill Farm in northern Mississippi. The goal of this thesis is to conduct a ground-penetrating radar (GPR) and shovel test survey to explore how changing landscapes simultaneously (re)create and destroy senses of place or Homescapes. Homescapes have received little attention in the field of archaeology and have not been applied to Euro-American Homescapes. I apply this theoretical construct in a novel way as a venture to further develop an avenue in archaeology to be collaborative and understand the past in a way that accurately reflects the realities of the past. I utilize historical records, oral histories, archaeological materials, and GPR to deepen our understanding of this site and to demonstrate the value of holistic archaeology and collaborating with the descendant community
Approximation of Optimal Control Surfaces for the Bass Model with Stochastic Dynamics
The Bass diffusion equation is a well-known and established modeling approach
for describing new product adoption in a competitive market. This model also
describes diffusion phenomena in various contexts: infectious disease spread
modeling and estimation, rumor spread on social networks, prediction of
renewable energy technology markets, among others. Most of these models,
however, consider a deterministic trajectory of the associated state variable
(e.g., market-share). In reality, the diffusion process is subject to noise,
and a stochastic component must be added to the state dynamics. The stochastic
Bass model has also been studied in many areas, such as energy markets and
marketing. Exploring the stochastic version of the Bass diffusion model, we
propose in this work an approximation of (stochastic) optimal control surfaces
for a continuous-time problem arising from a skew symmetric
evolutionary game, providing the stochastic counter-part of the Fourier-based
optimal control approximation already existent in the literature
A Multidimensional Fourier Approximation of Optimal Control Surfaces
This work considers the problem of approximating initial condition and
time-dependent optimal control and trajectory surfaces using multivariable
Fourier series. A modified Augmented Lagrangian algorithm for translating the
optimal control problem into an unconstrained optimization one is proposed and
two problems are solved: a quadratic control problem in the context of
Newtonian mechanics, and a control problem arising from an odd-circulant game
ruled by the replicator dynamics. Various computational results are presented.
Use of automatic differentiation is explored to circumvent the elaborated
gradient computation in the first-order optimization procedure. Furthermore,
mean square error bounds are derived for the case of one and two-dimensional
Fourier series approximations, inducing a general bound for problems of
dimensions
Multicolour interphase cytogenetics: 24 chromosome probes, 6 colours, 4 layers
From the late 1980s onwards, the use of DNA probes to visualise sequences on individual chromosomes (fluorescent in-situ hybridisation - FISH) revolutionised the study of cytogenetics. Following single colour experiments, more fluorochromes were added, culminating in a 24 colour assay that could distinguish all human chromosomes. Interphase cytogenetics (the detection of chromosome copy number in interphase nuclei) soon followed, however 24 colour experiments are hampered for this application as mixing fluorochromes to produce secondary colours produces images that are not easily distinguishable from overlapping signals. This study reports the development and use of a novel protocol, new fast hybridising FISH probes, and a bespoke image capture system for the assessment of chromosome copy number in interphase nuclei. The multicolour probe sets can be used individually or in sequential hybridisation layers to assess ploidy of all 24 human chromosomes in the same nucleus. Applications of this technique are in the investigation of chromosome copy number and the assessment of nuclear organisation for a range of different cell types including human sperm, cancer cells and preimplantation embryos
CHIANTI - An atomic database for emission lines. XI. EUV emission lines of Fe VII, Fe VIII and Fe IX observed by Hinode/EIS
A detailed study of emission lines from Fe VII, Fe VIII and Fe IX observed by
the EUV Imaging Spectrometer on board the Hinode satellite is presented.
Spectra in the ranges 170-212 A and 246-292 A show strongly enhanced lines from
the upper solar transition region (temperatures 5.4 <= log T <= 5.9) allowing a
number of new line identifications to be made. Comparisons of Fe VII lines with
predictions from a new atomic model reveal new plasma diagnostics, however
there are a number of disagreements between theory and observation for emission
line ratios insensitive to density and temperature, suggesting improved atomic
data are required. Line ratios for Fe VIII also show discrepancies with theory,
with the strong 185.21 and 186.60 lines under-estimated by 60-80 % compared to
lines between 192 and 198 A. A newly-identified multiplet between 253.9 and
255.8 A offers excellent temperature diagnostic opportunities relative to the
lines between 185-198 A, however the atomic model under-estimates the strength
of these lines by factors 3-6. Two new line identifications are made for Fe IX
at wavelengths 176.959 A and 177.594 A, while seven other lines between 186 and
200 A are suggested to be due to Fe IX but for which transition identifications
can not be made. The new atomic data for Fe VII and Fe IX are demonstrated to
significantly modify models for the response function of the TRACE 195 A
imaging channel, affecting temperature determinations from this channel. The
data will also affect the response functions for other solar EUV imaging
instruments such as SOHO/EIT, STEREO/EUVI and the upcoming AIA instrument on
the Solar Dynamics Observatory.Comment: 51 pages, submitted to Ap
The efficacy of the new SCD Response Compression System in the prevention of venous stasis
AbstractObjective: The current commercially available sequential intermittent pneumatic compression device used for the prevention of deep venous thrombosis has a constant cycle of 11 secondsâ compression and 60 secondsâ deflation. This deflation period ensures that the veins are filled before the subsequent cycle begins. It has been suggested that in some positions (eg, semirecumbent or sitting) and with different patients (eg, those with venous reflux), refilling of the veins may occur much earlier than 60 seconds, and thus a more frequent cycle may be more effective in expelling blood proximally. The aim of the study was to test the effectiveness of a new sequential compression system (the SCD Response Compression System), which has the ability to detect the change in the venous volume and to respond by initiating the subsequent cycle when the veins are substantially full. Methods: In an open controlled trial at an academic vascular laboratory, the SCD Response Compression System was tested against the existing SCD Sequel Compression System in 12 healthy volunteers who were in supine, semirecumbent, and sitting positions. The refilling time sensed by the device was compared with that determined from recordings of femoral vein flow velocity by the use of duplex ultrasound scan. The total volume of blood expelled per hour during compression was compared with that produced by the existing SCD system in the same volunteers and positions. Results: The refilling time determined automatically by the SCD Response Compression System varied from 24 to 60 seconds in the subjects tested, demonstrating individual patient variation. The refilling time (mean ± SD) in the sitting position was 40.6 ± 10.0 seconds, which was significantly longer (P <.001) than that measured in the supine and semirecumbent positions, 33.8 ± 4.1 and 35.6 ± 4.9 seconds, respectively. There was a linear relationship between the duplex scanâderived refill time (mean of 6 readings per leg) and the SCD Response deviceâderived refill time (r = 0.85, P <.001). The total volume of blood (mean ± SD) expelled per hour by the existing SCD Sequel device in the supine, semirecumbent, and sitting positions was 2.23 ± 0.90 L/h, 2.47 ± 0.86 L/h, and 3.28 ± 1.24 L/h, respectively. The SCD Response device increased the volume expelled to 3.92 ± 1.60 L/h or a 76% increase (P =.001) in the supine position, to 3.93 ± 1.55 L/h or a 59% increase (P =.001) in the semirecumbent position, and to 3.97 ± 1.42 L/h or a 21% increase (P =.026) in the sitting position. Conclusions: By achieving more appropriately timed compression cycles over time, the new SCD Response System is effective in preventing venous stasis by means of a new method that improves on the clinically documented effectiveness of the existing SCD system. Further studies testing its potential for improved efficacy in preventing deep venous thrombosis are justified. (J Vasc Surg 2000;32:932-40.
Updated Atomic Data and Calculations for X-ray Spectroscopy
We describe the latest release of AtomDB, version 2.0.2, a database of atomic
data and a plasma modeling code with a focus on X-ray astronomy. This release
includes several major updates to the fundamental atomic structure and process
data held within AtomDB, incorporating new ionization balance data,
state-selective recombination data, and updated collisional excitation data for
many ions, including the iron L-shell ions from Fe to Fe and
all of the hydrogen- and helium-like sequences. We also describe some of the
effects that these changes have on calculated emission and diagnostic line
ratios, such as changes in the temperature implied by the He-like G-ratios of
up to a factor of 2.Comment: Submitted to ApJ, 12 pages, 9 figure
The complete submillimetre spectrum of NGC 891
Submillimetre maps of NGC 891 have been obtained with the PRONAOS
balloon-borne telescope and with the ISOPHOT instrument on board the ISO
satellite. In this article, we also gather data from IRAS and SCUBA to present
the complete submillimetre spectrum of this nearby edge-on spiral galaxy. We
derive submillimetre emission profiles along the major axis. The modified
blackbody fits, assuming a single dust component, lead to temperatures of 19-24
K toward the centre and 18-20 K toward the edges, with possible variations of
the dust spectral index from 1.4 to 2. The two-component fits lead to a warm
component temperature of 29 K all along the galaxy with a cold component at 16
K. The interstellar medium masses derived by these two methods are quite
different: 4.6 x 10^9 Mo in the case of the one-component model and 12 x 10^9
Mo in the case of the two-component one. This two-component fit indicates that
the cold dust to warm dust ratio is 20 to 40, the highest values being in the
wings of this galaxy. Comparing to dust mass estimates, both estimations of the
ISM mass are consistent with a gas to dust mass ratio of 240, which is close to
the Milky Way value. Our results illustrate the importance of accurate
submillimetre spectra to derive masses of the interstellar medium in galaxies.Comment: 5 pages, 2 figures, accepted May 2003 in the MNRA
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