615 research outputs found
Oral mucosal precancer and cancer: a helpful discriminating clinical tool
The authors have collaborated with many colleagues in several countries in formulating a useful and practical
clinical tool for evaluating oral mucosal findings on routine examination.
Consideration of several factors including history, evolution of positive findings and clinical information allows
placement of examination results into one of three categories which are graded by a color scheme along a spectrum of concerns (green to red, or no concern to serious concern). Afforded to the clinician is a straightforward
grading system as a starting point for office end clinic use for all patients
The influence of lateral advection on the residual estuarine circulation : a numerical modeling study of the Hudson River Estuary
Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 39 (2009): 107-124, doi:10.1175/2008JPO3952.1.In most estuarine systems it is assumed that the dominant along-channel momentum balance is between the integrated pressure gradient and bed stress. Scaling the amplitude of the estuarine circulation based on this balance has been shown to have predictive skill. However, a number of authors recently highlighted important nonlinear processes that contribute to the subtidal dynamics at leading order. In this study, a previously validated numerical model of the Hudson River estuary is used to examine the forces driving the residual estuarine circulation and to test the predictive skill of two linear scaling relationships. Results demonstrate that the nonlinear advective acceleration terms contribute to the subtidal along-channel momentum balance at leading order. The contribution of these nonlinear terms is driven largely by secondary lateral flows. Under a range of forcing conditions in the model runs, the advective acceleration terms nearly always act in concert with the baroclinic pressure gradient, reinforcing the residual circulation. Despite the strong contribution of the nonlinear advective terms to the subtidal dynamical balance, a linear scaling accurately predicts the strength of the observed residual circulation in the model. However, this result is largely fortuitous, as this scaling does not account for two processes that are fundamental to the estuarine circulation. The skill of this scaling results because of the compensatory relationship between the contribution of the advective acceleration terms and the suppression of turbulence due to density stratification. Both of these processes, neither of which is accounted for in the linear scaling, increase the residual estuarine circulation but have an opposite dependence on tidal amplitude and, consequently, strength of stratification.This research was supported by the
Beacon Institute for Rivers and Estuaries—Woods
Hole Oceanographic Institution postdoctoral fellowship
program, as well as NSF Grants OCE-0452054 and
OCE-0451740
Comparative Benchmark Dose Modeling as a Tool to Make the First Estimate of Safe Human Exposure Levels to Lunar Dust
Brief exposures of Apollo Astronauts to lunar dust occasionally elicited upper respiratory irritation; however, no limits were ever set for prolonged exposure ot lunar dust. Habitats for exploration, whether mobile of fixed must be designed to limit human exposure to lunar dust to safe levels. We have used a new technique we call Comparative Benchmark Dose Modeling to estimate safe exposure limits for lunar dust collected during the Apollo 14 mission
Quantum control of EIT dispersion via atomic tunneling in a double-well Bose-Einstein condensate
Electromagnetically induced transparency (EIT) is an important tool for
controlling light propagation and nonlinear wave mixing in atomic gases with
potential applications ranging from quantum computing to table top tests of
general relativity. Here we consider EIT in an atomic Bose-Einstein Condensate
(BEC) trapped in a double well potential. A weak probe laser propagates through
one of the wells and interacts with atoms in a three-level
configuration. The well through which the probe propagates is dressed by a
strong control laser with Rabi frequency , as in standard EIT
systems. Tunneling between the wells at the frequency provides a coherent
coupling between identical electronic states in the two wells, which leads to
the formation of inter-well dressed states. The tunneling in conjunction with
the macroscopic interwell coherence of the BEC wave function, results in the
formation of two ultra-narrow absorption resonances for the probe field that
are inside of the ordinary EIT transparency window. We show that these new
resonances can be interpreted in terms of the inter-well dressed states and the
formation of a novel type of dark state involving the control laser and the
inter-well tunneling. To either side of these ultra-narrow resonances there is
normal dispersion with very large slope controlled by . For realistic values
of , the large slope of this dispersion yields group velocities for the
probe field that are two orders of magnitude slower than standard EIT systems.
We discuss prospects for observing these ultra-narrow resonances and the
corresponding regions of high dispersion experimentally
Effect of laser surface treatment on the corrosion and fatigue performance of aa5456-h116 alloys
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Generation of decoherence-free displaced squeezed states of radiation fields and a squeezed reservoir for atoms in cavity QED
We present a way to engineer an effective anti-Jaynes-Cumming and a
Jaynes-Cumming interaction between an atomic system and a single cavity mode
and show how to employ it in reservoir engineering processes. To construct the
effective Hamiltonian, we analyse considered the interaction of an atomic
system in a \{Lambda} configuration, driven by classical fields, with a single
cavity mode. With this interaction, we firstly show how to generate a
decoherence-free displaced squeezed state for the cavity field. In our scheme,
an atomic beam works as a reservoir for the radiation field trapped inside the
cavity, as employed recently by S. Pielawa et al. [Phys. Rev. Lett. 98, 240401
(2007)] to generate an Einstein-Podolsky-Rosen entangled radiation state in
high-Q resonators. In our scheme, all the atoms have to be prepared in the
ground state and, as in the cited article, neither atomic detection nor precise
interaction times between the atoms and the cavity mode are required. From this
same interaction, we can also generate an ideal squeezed reservoir for atomic
systems. For this purpose we have to assume, besides the engineered atom-field
interaction, a strong decay of the cavity field (i.e., the cavity decay must be
much stronger than the effective atom-field coupling). With this scheme, some
interesting effects in the dynamics of an atom in a squeezed reservoir could be
tested
Inhalation Toxicity of Ground Lunar Dust Prepared from Apollo-14 Soil
Within the decade one or more space-faring nations intend to return humans to the moon for more in depth exploration of the lunar surface and subsurface than was conducted during the Apollo days. The lunar surface is blanketed with fine dust, much of it in the respirable size range (<10 micron). Eventually, there is likely to be a habitable base and rovers available to reach distant targets for sample acquisition. Despite designs that could minimize the entry of dust into habitats and rovers, it is reasonable to expect lunar dust to pollute both as operations progress. Apollo astronauts were exposed briefly to dust at nuisance levels, but stays of up to 6 months on the lunar surface are envisioned. Will repeated episodic exposures to lunar dust present a health hazard to those engaged in lunar exploration? Using rats exposed to lunar dust by nose-only inhalation, we set out to investigate that question
On the suitability of slow strain rate tensile testing for assessing hydrogen embrittlement susceptibility
The onset of sub-critical crack growth during slow strain rate tensile
testing (SSRT) is assessed through a combined experimental and modeling
approach. A systematic comparison of the extent of intergranular fracture and
expected hydrogen ingress suggests that hydrogen diffusion alone is
insufficient to explain the intergranular fracture depths observed after SSRT
experiments in a Ni-Cu superalloy. Simulations of these experiments using a new
phase field formulation indicate that crack initiation occurs as low as 40% of
the time to failure. The implications of such sub-critical crack growth on the
validity and interpretation of SSRT metrics are then explored
Myocardial extracellular volume quantification by cardiovascularagn magnetic resonance and computed tomography
Purpose of review This review article discusses the evolution of extracellular volume (ECV) quantification using both cardiovascular magnetic resonance (CMR) and computed tomography (CT).
Recent findings Visualizing diffuse myocardial fibrosis is challenging and until recently, was restricted to the domain of the
pathologist. CMR and CT both use extravascular, extracellular contrast agents, permitting ECV measurement. The evidence base
around ECV quantification by CMR is growing rapidly and just starting in CT. In conditions with high ECV (amyloid, oedema
and fibrosis), this technique is already being used clinically and as a surrogate endpoint. Non-invasive diffuse fibrosis quantification is also generating new biological insights into key cardiac diseases.
Summary CMR and CT can estimate ECV and in turn diffuse myocardial fibrosis, obviating the need for invasive
endomyocardial biopsy. CT is an attractive alternative to CMR particularly in those individuals with contraindications to the
latter. Further studies are needed, particularly in CT
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