5,567 research outputs found
Recommended from our members
Near-infrared imaging of demineralization on the occlusal surfaces of teeth without the interference of stains.
Most new caries lesions are found in the pits and fissures of the occlusal surface. Radiographs have extremely low sensitivity for early occlusal decay, and by the time the lesion is severe enough to appear on a radiograph, it typically has penetrated well into the dentin and surgical intervention is required. The occlusal surfaces are often heavily stained, and visual and tactile detection have poor sensitivity and specificity. Previous near-infrared imaging studies at wavelengths beyond 1300 nm have demonstrated that stains are not visible and demineralization on the occlusal surfaces can be viewed without interference from stains. The objective of our study is to determine how the contrast between sound and lesion areas on occlusal surfaces varies with wavelength from the visible to 2350 nm and determine to what degree stains interfere with that contrast. The lesion contrast for reflectance is measured in 55 extracted teeth with suspected occlusal lesions from 400 to 2350 nm employing silicon and indium gallium arsenide imaging arrays. In addition, the lesion contrast is measured on 25 extracted teeth with suspected occlusal lesions from 400 to 1600 nm in reflectance and from 830 to 1400 nm in transillumination before and after stains are removed using a ultrasonic scaler. The highest lesion contrast in reflectance is measured at wavelengths >1700 nm. Stains interfere significantly at wavelengths <1150 nm (400 to 1150) for both reflectance and transillumination measurements. Our study suggests that the optimum wavelengths for imaging decay in the occlusal surfaces are >1700 nm for reflectance (1700 to 2350 nm) and near 1300 nm (1250 to 1350 nm) for transillumination
Near-inertial wave scattering by random flows
The impact of a turbulent flow on wind-driven oceanic near-inertial waves is
examined using a linearised shallow-water model of the mixed layer. Modelling
the flow as a homogeneous and stationary random process with spatial scales
comparable to the wavelengths, we derive a transport (or kinetic) equation
governing wave-energy transfers in both physical and spectral spaces. This
equation describes the scattering of the waves by the flow which results in a
redistribution of energy between waves with the same frequency (or,
equivalently, with the same wavenumber) and, for isotropic flows, in the
isotropisation of the wave field. The time scales for the scattering and
isotropisation are obtained explicitly and found to be of the order of tens of
days for typical oceanic parameters. The predictions inferred from the
transport equation are confirmed by a series of numerical simulations.
Two situations in which near-inertial waves are strongly influenced by flow
scattering are investigated through dedicated nonlinear shallow-water
simulations. In the first, a wavepacket propagating equatorwards as a result
from the -effect is shown to be slowed down and dispersed both zonally
and meridionally by scattering. In the second, waves generated by moving
cyclones are shown to be strongly disturbed by scattering, leading again to an
increased dispersion.Comment: Accepted for publication in Phys. Rev. Fluid
Recommended from our members
Lifespan-increasing drug nordihydroguaiaretic acid inhibits p300 and activates autophagy.
Aging is characterized by the progressive loss of physiological function in all organisms. Remarkably, the aging process can be modulated by environmental modifications, including diet and small molecules. The natural compound nordihydroguaiaretic acid (NDGA) robustly increases lifespan in flies and mice, but its mechanism of action remains unclear. Here, we report that NDGA is an inhibitor of the epigenetic regulator p300. We find that NDGA inhibits p300 acetyltransferase activity in vitro and suppresses acetylation of a key p300 target in histones (i.e., H3K27) in cells. We use the cellular thermal shift assay to uniquely demonstrate NDGA binding to p300 in cells. Finally, in agreement with recent findings indicating that p300 is a potent blocker of autophagy, we show that NDGA treatment induces autophagy. These findings identify p300 as a target of NDGA and provide mechanistic insight into its role in longevity
Effective Assessment of Power Standing Device to Adults with Permanent Lower Limb Paralysis
Introduction: Standing routine is a known beneficial daily activity for both healthy and disabled persons, especially those with permanent lower limb paralysis. However, the prescription of standing device for adults with permanent paralysis was inadequate and non-standard in existing local practice because of lack of good design and evidence based funding support. Objective: In view of the availability of new advances in power standing device, we aim to perform an effective health technology assessment (HTA) from professional and users perspectives to develop the decision pathway in prescription for long term home use. Methodology: A functional test and social cost analysis was performed on one high cost new standing mobile devices in recent market. A practical workshop and surveys were performed to collect feedback from 24 healthcare professionals and 8 expert users on a spectrum of new standing mobile device. Results: From the survey results, there was consensus among all participants that ‘Standing’ as daily routine at home is essential and beneficial. 62.5% of healthcare professionals would provide training to users and their cares to facilitate users to perform standing at home. Eight factors were identified from factor analysis in affecting the choice of standing devices for home use by healthcare professionals and users. Users scored high (mean=9.25/10) in “compliance with the new power standing mobile device”. The cost analysis showed considerable savings in social costs in using even the high-cost power standing mobile device. Discussion: The group welcomed power standing device with or without mobile function to support their standing activity at home. A possible clinical decision for prescribing different standing devices with identified factors was summarized. Conclusion: More recent researches have reported the negative health issues associated with prolonged sitting. With more innovative product designs, the power standing devices with or without mobile function is a new concept welcomed by both healthcare professionals and users in promotion of their health, preventing complications as well as independent living in home environment. A larger scale of HTA with structured cost-effectiveness analysis is essential to inform the healthcare resources planners
The Effect of Sodium on the Catalytic Activity of ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5 for the Transesterification of Vegetable Oil with Methanol
In order to elucidate the effect of sodium on the activity of ZSM-5 supported metal oxides catalysts (ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5) for the transesterification of soybean oil with methanol, ZSM-5 supported metal oxides were prepared with and without sodium hydroxide by impregnation. The metal compositions of the ZSM-5 supported metal oxide catalysts and the metal concentrations dissolved from the catalysts to the methylester phase were measured by SEM-EDS and inductive coupled plasma spectroscopy, respectively. The catalytic activity of ZnO-Al2O3/ZSM-5 and SnO-Al2O3/ZSM-5 containing sodium did not originate from surface metal oxides sites, but from surface sodium sites or dissolved sodium leached from the catalyst surface
- …