The wall-pressure fluctuations beneath a turbulent boundary layer have been conditionally sampled on basis of the high-frequency activity pressure themselves, streamwise velocity in vicinity wall, and excursions wall. This has led to identification characteristic fluctuation pattern which is associated with burst–sweep cycle events wall region. form an overpressure over extent about 1·5−2·0δ*, region underpressure minimum either side it, distance between minima being 3·0−3·5δ*. convected at...

Directly comparable spectral measurements with piezoelectric and pinhole-microphone transducers show pinhole to be significantly in error. The increase measured rms pressure reduction of transducer size is not nearly as dramatic previous work has suggested.

Introduction Increasing episodes of violence against healthcare workers (HCWs) are growing global concern. The World Health Organization (WHO) reports 8% - 38% HCWs having experienced physical at least once in their lifetime. Healthcare settings recognized as high-risk workplaces by the WHO. In response to widespread protests murder a house surgeon Kottarakara Taluk Hospital 2023, government Kerala strengthened 2012 legislation with Service Persons, and Institutions (Prevention Violence...

The smoke wire technique was used to initial formation and growth of turbulent spots in a laminar boundary layer. were observed result not from the breakdown wave packets arising at spot generator but longitudinal structures which preceded packets. original packet turn ultimately take form oblique waves trailing spot. These had little apparent involvement did appear be associated with new within region visualized.

We describe initial experiences with an in-house, fast, large field-of-view optical-CT telecentric scanner (the Duke Large field of view Optical-CT Scanner (DLOS)). The DLOS system is designed to enable imaging dosimeters up 24 cm in diameter a spatial resolution 1 mm3, approximately 10 minutes. These capabilities render the unique device at present. scaled version early prototypes our lab. This scaling introduces several challenges, including accurate measurement greatly increased range...

PRESAGETM dosimeter has been proved useful for 3D dosimetry in conventional photon therapy and IMRT [1–5]. Our objective is to examine the use of verification depth dose distribution proton beam therapy. Three samples were irradiated with a 79 MeV un-modulated beam. Percent profile measured from compared data obtained water phantom using parallel plate Advanced Markus chamber. The Bragg-peak position determined within 2 mm measurements water. shows highly linear response dose. However, also...

A midsized broad beam Optical-CT scanner is being developed for collaborative research between Duke and the Radiological Physics Center (RPC). The Midsized Scanner (DMOS-RPC) designed to be compatible with several of RPC phantoms, including head neck, stereotactic SRS, lung phantoms. Preliminary data investigating basic performance described. Two 10 cm PRESAGE cylinders were irradiated simple test plans. Projections ~80 μm resolution each dosimeter collected at 1 degree intervals over a full...

The purpose of this study is to determine whether organ sparing and target coverage can be simultaneously maintained for pencil beam scanning (PBS) proton therapy treatment thoracic tumors in the presence motion, stopping power uncertainties patient setup variations. Ten consecutive patients that were previously treated with 66.6/1.8 Gy (RBE) using double scattering (DS) replanned PBS. Minimum maximum intensity images from 4DCT used introduce flexible smearing determination specific PTV...

Achieving adequate verification and quality-assurance (QA) for radiosurgery treatment of trigeminal-neuralgia (TGN) is particularly challenging because the combination very small fields, high doses, complex irradiation geometries (multiple gantry couch combinations). TGN treatments have extreme requirements dosimetry tools QA techniques, to ensure verification. In this work we evaluate potential Presage/Optical-CT system as a tool distributions in high-resolution 3D. A was planned delivered...

The serious impact of the Covid-19 pandemic underscores need for rapid, reliable, and high-throughput diagnosis methods infection. Current analytical methods, either point-of-care or centralized detection, are not able to satisfy requirements patient-friendly testing, high demand, reliability results. Here, we propose a two-point separation on-demand diagnostic strategy that uses laser desorption/ionization time-of-flight mass spectrometry (LDI-TOF MS) adopts stable yet cleavable ionic probe...

Clinical recommendations to address tumor motion management have been derived from studies dealing with simulations and 2D measurements. 3D measurements may provide more insight possibly alter the current guidelines. This study provides an initial look at true involving leaf deliveries by use of a phantom PRESAGE/DLOS dosimetry system. An IMRT VMAT plan were delivered analyzed means DVHs determine whether expansion treatment volumes based on known imaging adequately cover target. confirmed...

Optical-CT performed with a broad spectrum light source can lead to inaccurate reconstructed attenuation coefficients (and hence dose) due 'spectral warping' as the beam passes through dosimeter. Some wavelengths will be attenuated more strongly than others depending on absorption of radiochromic A simulation was run characterize error introduced by warping phenomena. Simulations typical dosimeter and delivered dose (6cm diameter, 2 Gy irradiation) showed in >12% when compared those obtained...

The flow of a laminar boundary layer into suction slot has been examined experimentally in low-turbulence water channel. Dimensional analysis shows that the Reynolds number and parameter describes mean velocity gradient above are important variables problem. Measurements reported length scales separation region within slot-pressure loss. These data correlate terms similarity may be used as predictive design tool. mean-flow profiles slot, both upstream downstream directions, were also...

The RadBall dosimeter is a novel device for providing 3-D information on the magnitude and distribution of contaminant sources unknown radiation in given hot cell, glovebox, or contaminated room. presently under evaluation by National Nuclear Lab (NNL, UK) Savannah River Laboratory (SRNL, US), application as diagnostic such contaminants nuclear industry. A critical component technique imaging dose recorded using optical-CT scanning. Here we present our initial investigations Duke Mid-sized...

Optical computed tomography (optical-CT) and optical-emission (optical-ECT) are new techniques for imaging the 3D structure function (including gene expression) of whole unsectioned tissue samples. This work presents a method improving quantitative accuracy optical-ECT by correcting 'self'-attenuation photons emitted within sample. The correction is analogous to commonly applied in single-photon-emission reconstruction. performance was investigated application transparent cylindrical gelatin...

Purpose: To commission and benchmark a 3D dosimetry system for clinical use, in particular, verification commissioning of complex radiation treatments like VMAT, IMRT gated treatments. The is composed two parts: radiochromic plastic dosimeter Presage, which responds to absorbed dose with linear change optical‐density; the Duke Large field view Optical‐CT Scanner (DLOS). Methods: DLOS involved creating stray light spectral corrections, determining dynamic range, spatial resolution, noise,...

Six base of skull IMRT treatment plans were delivered to Presage dosimeters within the RPC Head and Neck Phantom for quality assurance (QA) verification. Isotropic 2mm 3D data acquired by optical-CT scanning with DLOS system (Duke Large Optical-CT Scanner) compared Eclipse (Varian) plan. Normalized Dose Distribution (NDD) pass rates obtained a number criteria. High dosimetry was observed from system, illustrated here through colormaps, isodose lines, profiles. Excellent agreement planned...