320 research outputs found
Diagnostic Accuracy of Confocal Laser Endomicroscopy for the Diagnosis of Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis
Published: 25 November 2021Background: Advances in treatment approaches for patients with oral squamous cell carcinoma (OSCC) have been unsuccessful in preventing frequent recurrences and distant metastases, leading to a poor prognosis. Early detection and prevention enable an improved 5-year survival and better prognosis. Confocal Laser Endomicroscopy (CLE) is a non-invasive imaging instrument that could enable an earlier diagnosis and possibly help in reducing unnecessary invasive surgical procedures. Objective: To present an up to date systematic review and meta-analysis assessing the diagnostic accuracy of CLE in diagnosing OSCC. Materials and Methods. PubMed, Scopus, and Web of Science databases were explored up to 30 June 2021, to collect articles concerning the diagnosis of OSCC through CLE. Screening: data extraction and appraisal was done by two reviewers. The quality of the methodology followed by the studies included in this review was assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. A random effects model was used for the meta-analysis. Results: Six studies were included, leading to a total number of 361 lesions in 213 patients. The pooled sensitivity and specificity were 95% (95% CI, 92–97%; I2 = 77.5%) and 93% (95% CI, 90–95%; I2 = 68.6%); the pooled positive likelihood ratios and negative likelihood ratios were 10.85 (95% CI, 5.4–21.7; I2 = 55.9%) and 0.08 (95% CI, 0.03–0.2; I2 = 83.5%); and the pooled diagnostic odds ratio was 174.45 (95% CI, 34.51–881.69; I2 = 73.6%). Although risk of bias and heterogeneity is observed, this study validates that CLE may have a noteworthy clinical influence on the diagnosis of OSCC, through its high sensitivity and specificity. Conclusions: This review indicates an exceptionally high sensitivity and specificity of CLE for diagnosing OSCC. Whilst it is a promising diagnostic instrument, the limited number of existing studies and potential risk of bias of included studies does not allow us to draw firm conclusions. A conclusive inference can be drawn when more studies, possibly with homogeneous methodological approach, are performed.Sneha Sethi, Xiangqun Ju, Richard M. Logan, Paul Sambrook, Robert A. McLaughlin and Lisa M. Jamieso
Optimal mixing of buoyant jets and plumes in stratified fluids: Theory and experiments
The influence of ambient fluid stratification on buoyant miscible jets and plumes is studied theoretically and experimentally. Given a fixed set of jet/plume parameters, and an ambient fluid stratification sandwiched between top and bottom homogeneous densities, a theoretical criterion is identified to show how step-like density profiles constitute the most effective mixers within a broad class of stable density transitions. This is assessed both analytically and experimentally, respectively by establishing rigorous a priori estimates on generalized Morton-Taylor-Turner (MTT) models (Morton et al., Proc. R. Soc. Lond. A, vol. 234, 1956, pp. 1-23; Fischer et al., Mixing in Inland and Coastal Waters. Academic, 1979), and by studying a critical phenomenon determined by the distance between the jet/plume release height with respect to the depth of the ambient density transition. For fluid released sufficiently close to the background density transition, the buoyant jet fluid escapes and rises indefinitely. For fluid released at locations lower than a critical depth, the buoyant fluid stops rising and is trapped indefinitely. A mathematical formulation providing rigorous estimates on MTT models is developed along with nonlinear jump conditions and an exact critical-depth formula that is in good quantitative agreement with the experiments. Our mathematical analysis provides rigorous justification for the critical trapping/escaping criteria, first presented in Caulfield & Woods (J. Fluid Mech., vol. 360, 1998, pp. 229-248), within a class of algebraic density decay rates. Further, the step-like background stratification is shown to be the most efficient mixing profile amongst a broad family of stably stratified profiles sharing the same density transition within a fixed distance. Finally, the analysis uncovers surprising differences between the Gaussian and top-hat profile closures concerning initial mixing of the jet and ambient fluid
Ephemeral aggregate layers in the water column leave lasting footprints in the carbon cycle
Marine aggregates play a critical role in the biological pump, both as a dominant component of carbon flux and as hotspots for organic matter remineralization by microbial communities. In this study, we used laboratory experiments to investigate how aggregate thin layers, such as those commonly found in the coastal ocean, affect the distribution of bacteria and their activity. Diatom aggregates were added to a stratified water column, forming layers within which both microbial concentration and extracellular enzyme activity were substantially increased relative to background levels. Importantly, this enhancement of bacterial concentration and activity persisted long after the marine snow aggregates settled through the tank—that is, 10 times longer than the duration of the aggregate layer at the density interface. Thus, these small-scale microbial interactions within aggregate layers leave behind considerable “carbon processing footprints” in the water column that may affect biogeochemical cycles at much larger temporal and spatial scales
Review article: MHD wave propagation near coronal null points of magnetic fields
We present a comprehensive review of MHD wave behaviour in the neighbourhood
of coronal null points: locations where the magnetic field, and hence the local
Alfven speed, is zero. The behaviour of all three MHD wave modes, i.e. the
Alfven wave and the fast and slow magnetoacoustic waves, has been investigated
in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null
points, for a variety of assumptions, configurations and geometries. In
general, it is found that the fast magnetoacoustic wave behaviour is dictated
by the Alfven-speed profile. In a plasma, the fast wave is focused
towards the null point by a refraction effect and all the wave energy, and thus
current density, accumulates close to the null point. Thus, null points will be
locations for preferential heating by fast waves. Independently, the Alfven
wave is found to propagate along magnetic fieldlines and is confined to the
fieldlines it is generated on. As the wave approaches the null point, it
spreads out due to the diverging fieldlines. Eventually, the Alfven wave
accumulates along the separatrices (in 2D) or along the spine or fan-plane (in
3D). Hence, Alfven wave energy will be preferentially dissipated at these
locations. It is clear that the magnetic field plays a fundamental role in the
propagation and properties of MHD waves in the neighbourhood of coronal null
points. This topic is a fundamental plasma process and results so far have also
lead to critical insights into reconnection, mode-coupling, quasi-periodic
pulsations and phase-mixing.Comment: 34 pages, 5 figures, invited review in Space Science Reviews => Note
this is a 2011 paper, not a 2010 pape
Potential for Supernova Neutrino Detection in MiniBooNE
The MiniBooNE detector at Fermilab is designed to search for oscillation appearance at and to make a
decisive test of the LSND signal. The main detector (inside a veto shield) is a
spherical volume containing 0.680 ktons of mineral oil. This inner volume,
viewed by 1280 phototubes, is primarily a \v{C}erenkov medium, as the
scintillation yield is low. The entire detector is under a 3 m earth
overburden. Though the detector is not optimized for low-energy (tens of MeV)
events, and the cosmic-ray muon rate is high (10 kHz), we show that MiniBooNE
can function as a useful supernova neutrino detector. Simple trigger-level cuts
can greatly reduce the backgrounds due to cosmic-ray muons. For a canonical
Galactic supernova at 10 kpc, about 190 supernova
events would be detected. By adding MiniBooNE to the international network of
supernova detectors, the possibility of a supernova being missed would be
reduced. Additionally, the paths of the supernova neutrinos through Earth will
be different for MiniBooNE and other detectors, thus allowing tests of
matter-affected mixing effects on the neutrino signal.Comment: Added references, version to appear in PR
Photon interferometry and size of the hot zone in relativistic heavy ion collisions
The parameters obtained from the theoretical analysis of the single photon
spectra observed by the WA98 collaboration at SPS energies have been used to
evaluate the two photon correlation functions. The single photon spectra and
the two photon correlations at RHIC energies have also been evaluated, taking
into account the effects of the possible spectral change of hadrons in a
thermal bath. We find that the ratio for SPS and
for RHIC energy.Comment: text changed, figures adde
Pulsar Timing and its Application for Navigation and Gravitational Wave Detection
Pulsars are natural cosmic clocks. On long timescales they rival the
precision of terrestrial atomic clocks. Using a technique called pulsar timing,
the exact measurement of pulse arrival times allows a number of applications,
ranging from testing theories of gravity to detecting gravitational waves. Also
an external reference system suitable for autonomous space navigation can be
defined by pulsars, using them as natural navigation beacons, not unlike the
use of GPS satellites for navigation on Earth. By comparing pulse arrival times
measured on-board a spacecraft with predicted pulse arrivals at a reference
location (e.g. the solar system barycenter), the spacecraft position can be
determined autonomously and with high accuracy everywhere in the solar system
and beyond. We describe the unique properties of pulsars that suggest that such
a navigation system will certainly have its application in future astronautics.
We also describe the on-going experiments to use the clock-like nature of
pulsars to "construct" a galactic-sized gravitational wave detector for
low-frequency (f_GW ~1E-9 - 1E-7 Hz) gravitational waves. We present the
current status and provide an outlook for the future.Comment: 30 pages, 9 figures. To appear in Vol 63: High Performance Clocks,
Springer Space Science Review
Stochastic Production Of Kink-Antikink Pairs In The Presence Of An Oscillating Background
We numerically investigate the production of kink-antikink pairs in a
dimensional field theory subject to white noise and periodic driving.
The twin effects of noise and periodic driving acting in conjunction lead to
considerable enhancement in the kink density compared to the thermal
equilibrium value, for low dissipation coefficients and for a specific range of
frequencies of the oscillating background. The dependence of the kink-density
on the temperature of the heat bath, the amplitude of the oscillating
background and value of the dissipation coefficient is also investigated. An
interesting feature of our result is that kink-antikink production occurs even
though the system always remains in the broken symmetry phase.Comment: Revtex, 21 pages including 7 figures; more references adde
Estudo fitoquímico biomonitorado pelos ensaios de toxicidade frente à Artemia salina e de atividade antiplasmódica do caule de aninga (Montrichardia linifera)
The Number Of Magnetic Null Points In The Quiet Sun Corona
The coronal magnetic field above a particular photospheric region will vanish
at a certain number of points, called null points. These points can be found
directly in a potential field extrapolation or their density can be estimated
from Fourier spectrum of the magnetogram. The spectral estimate, which assumes
that the extrapolated field is random, homogeneous and has Gaussian statistics,
is found here to be relatively accurate for quiet Sun magnetograms from SOHO's
MDI. The majority of null points occur at low altitudes, and their distribution
is dictated by high wavenumbers in the Fourier spectrum. This portion of the
spectrum is affected by Poisson noise, and as many as five-sixths of null
points identified from a direct extrapolation can be attributed to noise. The
null distribution above 1500 km is found to depend on wavelengths that are
reliably measured by MDI in either its low-resolution or high-resolution mode.
After correcting the spectrum to remove white noise and compensate for the
modulation transfer function we find that a potential field extrapolation
contains, on average, one magnetic null point, with altitude greater than 1.5
Mm, above every 322 square Mm patch of quiet Sun. Analysis of 562 quiet Sun
magnetograms spanning the two latest solar minimum shows that the null point
density is relatively constant with roughly 10% day-to-day variation. At
heights above 1.5 Mm, the null point density decreases approximately as the
inverse cube of height. The photospheric field in the quiet Sun is well
approximated as that from discrete elements with mean flux 1.0e19 Mx
distributed randomly with density n=0.007 per square Mm
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