216 research outputs found
A Method for siting and prioritizing the removal of derelict vessels in Florida Coastal Waters: test applications in the Florida Keys
Increased boating activities and new waterfront developments have contributed an
estimated 3,000 dismantled, abandoned, junked, wrecked, derelict vessels to Florida
coastal waters. This report outlines a method of siting and prioritizing derelict vessel
removal using the Florida Keys as a test area. The data base was information on 240
vessels, obtained from Florida Marine Patrol files. Vessel location was plotted on 1:250,000
regional and 1:5,000 and 1:12,000 site maps. Type of vessel, length, hull material, engine,
fuel tanks, overall condition, afloat and submerged characteristics, and accessibility, were
used to derive parametric site indices of removal priority and removal difficulty.
Results indicate 59 top priority cases which should be the focus of immediate clean
up efforts in the Florida Keys. Half of these cases are rated low to moderate in removal
difficulty; the remainder are difficult to remove. Removal difficulty is a surrogate for
removal cost: low difficulty -low cost, high difficulty - high cost. The rating scheme offers
coastal planners options of focusing removal operations either on (1) specific areas with
clusters of high priority derelict vessels or on (2) selected targeted derelicts at various,
specific locations. (PDF has 59 pages.
A Study of Mormon Errors in View of the Holy Bible
https://digitalcommons.acu.edu/crs_books/1261/thumbnail.jp
A double-slit `which-way' experiment on the complementarity--uncertainty debate
A which-way measurement in Young's double-slit will destroy the interference
pattern. Bohr claimed this complementarity between wave- and particle behaviour
is enforced by Heisenberg's uncertainty principle: distinguishing two positions
a distance s apart transfers a random momentum q \sim \hbar/s to the particle.
This claim has been subject to debate: Scully et al. asserted that in some
situations interference can be destroyed with no momentum transfer, while
Storey et al. asserted that Bohr's stance is always valid. We address this
issue using the experimental technique of weak measurement. We measure a
distribution for q that spreads well beyond [-\hbar/s, \hbar/s], but
nevertheless has a variance consistent with zero. This weakvalued
momentum-transfer distribution P_{wv}(q) thus reflects both sides of the
debate.Comment: 13 pages, 4 figure
High-precision position control of a heavy-lift manipulator in a dynamic environment
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, June 2005."June 2005."Includes bibliographical references (leaves 81-83).This thesis considers the control of a heavy-lift serial manipulator operating on the deck of a large ocean vessel. This application presents a unique challenge for high- precision control because the system must contend with both high levels of joint friction and oscillatory motions in the manipulator's base. Due to the uncontrolled outdoor environment, the behavior of these disturbances in the field cannot be accurately predicted using models developed offline. To achieve high-precision control, the system must therefore be capable of effectively estimating and compensating for these disturbances online. This thesis presents the design of a position control system to allow high-precision control of the manipulator's payload by a human user. The design features a standard decentralized linear control architecture augmented by a combination of adaptive and sensor-based techniques to estimate and compensate for base-motions and joint friction. A procedure is also suggested by which a parametric friction model can be extracted from adaptive estimates recorded over a period of time. This extracted model can be used to temporarily replace the adaptive estimation in compensating for joint friction when the manipulator is in contact with the environment. Performance of the control methods developed here are evaluated using simulation studies conducted with a high-fidelity dynamic model of the mechanical system. These studies demonstrate the tracking capability of the control system for various representative tasks.by Justin R. Garretson.S.M
Politeness at work in the Clinton Email Corpus: A first look at the effects of status and gender
This article introduces the Clinton Email Corpus, comprising 33,000 recently released email messages sent to and from Hillary Clinton during her tenure as United States Secretary of State, and presents the results of a first investigation into the effect of status and gender on politeness-related linguistic choices within the corpus, based on a sample of 500 emails. We describe the composition of the corpus and mention the technical challenges inherent in its creation, and then present the 500-email subset, in which all messages are categorized according to sender and recipient gender, position in the workplace hierarchy, and personal closeness to Clinton. The analysis looks at the most frequent bigrams in each of these subsets as a starting point for the identification of linguistic differences. We find that the main differences relate to the content and function of the messages rather than their tone. Individuals lower in the hierarchy but not in Clinton’s inner circle are more often engaged in practical tasks, while members of the inner circle primarily discuss issues and use email to arrange in-person conversations. Clinton herself is generally found to engage neither in extensive politeness nor in overt displays of power. These findings present further evidence of how corpus linguistics can be used to advance our understanding of workplace pragmatics
Measuring measurement--disturbance relationships with weak values
Using formal definitions for measurement precision {\epsilon} and disturbance
(measurement backaction) {\eta}, Ozawa [Phys. Rev. A 67, 042105 (2003)] has
shown that Heisenberg's claimed relation between these quantities is false in
general. Here we show that the quantities introduced by Ozawa can be determined
experimentally, using no prior knowledge of the measurement under investigation
--- both quantities correspond to the root-mean-squared difference given by a
weak-valued probability distribution. We propose a simple three-qubit
experiment which would illustrate the failure of Heisenberg's
measurement--disturbance relation, and the validity of an alternative relation
proposed by Ozawa
Dark Energy in an Axion Model with Explicit Z(N) Symmetry Breaking
We point out that a well known axion model with an explicit Z(N) symmetry
breaking term predicts both dark energy and cold dark matter. We estimate the
parameters of this model which fit the observed densities of the dark
components of the universe. We find that the parameters do not conflict with
any observations.Comment: 5 pages, minor change
Transgelin Induces Dysfunction of Fetal Endothelial Colony-Forming Cells From Gestational Diabetic Pregnancies
Fetal exposure to gestational diabetes mellitus (GDM) predisposes children to future health complications including hypertension and cardiovascular disease. A key mechanism by which these complications occur is through the functional impairment of vascular progenitor cells, including endothelial colony-forming cells (ECFCs). Previously, we showed that fetal ECFCs exposed to GDM have decreased vasculogenic potential and altered gene expression. In this study, we evaluate whether transgelin (TAGLN), which is increased in GDM-exposed ECFCs, contributes to vasculogenic dysfunction. TAGLN is an actin-binding protein involved in the regulation of cytoskeletal rearrangement. We hypothesized that increased TAGLN expression in GDM-exposed fetal ECFCs decreases network formation by impairing cytoskeletal rearrangement resulting in reduced cell migration. To determine if TAGLN is required and/or sufficient to impair ECFC network formation, TAGLN was reduced and overexpressed in ECFCs from GDM and uncomplicated pregnancies, respectively. Decreasing TAGLN expression in GDM-exposed ECFCs improved network formation and stability as well as increased migration. In contrast, overexpressing TAGLN in ECFCs from uncomplicated pregnancies decreased network formation, network stability, migration, and alignment to laminar flow. Overall, these data suggest that increased TAGLN likely contributes to the vasculogenic dysfunction observed in GDM-exposed ECFCs, as it impairs ECFC migration, cell alignment, and network formation. Identifying the molecular mechanisms underlying fetal ECFC dysfunction following GDM exposure is key to ascertain mechanistically the basis for cardiovascular disease predisposition later in life
The Cosmic Microwave Background and Helical Magnetic Fields: the tensor mode
We study the effect of a possible helicity component of a primordial magnetic
field on the tensor part of the cosmic microwave background temperature
anisotropies and polarization. We give analytical approximations for the tensor
contributions induced by helicity, discussing their amplitude and spectral
index in dependence of the power spectrum of the primordial magnetic field. We
find that an helical magnetic field creates a parity odd component of gravity
waves inducing parity odd polarization signals. However, only if the magnetic
field is close to scale invariant and if its helical part is close to maximal,
the effect is sufficiently large to be observable. We also discuss the
implications of causality on the magnetic field spectrum.Comment: We have corrected a normalisation error which was pointed out to us
by Antony Lewis. It enhances our limits on the magnetic fields by
(2\pi)^{3/4} ~
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