WE-AB-BRB-08: Progress Towards a 2D OSL Dosimetry System Using Al2O3:C Films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, M F; Yukihara, E; Schnell, E

Purpose: To develop a 2D dosimetry system based on the optically stimulated luminescence (OSL) of Al{sub 2}O{sub 3}:C films for medical applications. Methods: A 2D laser scanning OSL reader was built for readout of newly developed Al2O3:C films (Landauer Inc.). An image reconstruction algorithm was developed to correct for inherent effects introduced by reader design and detector properties. The system was tested using irradiations with photon and carbon ion beams. A calibration was obtained using a 6 MV photon beam from clinical accelerator and the dose measurement precision was tested using a range of doses and different dose distributions (flatmore » field and wedge field). The dynamic range and performance of the system in the presence of large dose gradients was also tested using 430 MeV/u {sup 12}C single and multiple pencil beams. All irradiations were performed with Gafchromic EBT3 film for comparison. Results: Preliminary results demonstrate a near-linear OSL dose response to photon fields and the ability to measure dose in dose distributions such as flat field and wedge field. Tests using {sup 12}C pencil beam demonstrate ability to measure doses over four orders of magnitude. The dose profiles measured by the OSL film generally agreed well with that measured by the EBT3 film. The OSL image signal-to-noise ratio obtained in the current conditions require further improvement. On the other hand, EBT3 films had large uncertainties in the low dose region due to film-to-film or intra-film variation in the background. Conclusion: A 2D OSL dosimetry system was developed and initial tests have demonstrated a wide dynamic range as well as good agreement between the delivered and measured doses. The low background, wide dynamic range and wide range of linearity in dose response observed for the Al{sub 2}O{sub 3}:C OSL film can be beneficial for dosimetry in radiation therapy applications, especially for small field dosimetry. This work has been funded by Landauer Inc. Dr. Eduardo G. Yukihara also would like to thank the Alexander von Humboldt Foundation for his support at the DKFZ.« less

Optically stimulated luminescence in Cu+ doped lithium orthophosphate

NASA Astrophysics Data System (ADS)

Barve, R. A.; Patil, R. R.; Moharil, S. V.; Bhatt, B. C.; Kulkarni, M. S.

2015-02-01

Optically stimulated luminescence (OSL) in Cu+ doped Li3PO4 synthesized by co-precipitation technique using different phosphorus precursors was studied. Changes in the luminescent properties were observed with change in the phosphorus precursors. All the synthesized phosphors showed intense fading but the OSL sensitivity was comparable to that of the commercially available Al2O3:C (Landauer Inc.). In general, BSL (blue stimulated luminescence) decay was very fast but the GSL (green stimulated luminescence) decay was comparable to that of Al2O3:C phosphor. Phosphors with fast decay, good sensitivity and intense fading are suitable for real-time dosimetry. Therefore, Cu-doped Li3PO4 could be developed for real-time dosimetry using a fiber optic based OSL reader system.

GryphSens: A Smartphone-Based Portable Diagnostic Reader for the Rapid Detection of Progesterone in Milk

PubMed Central

Jang, Hyunwook; Ahmed, Syed Rahin; Neethirajan, Suresh

2017-01-01

Enzyme-linked immunosorbent assay (ELISA) is a popular assay technique for the detection and quantification of various biological substances due its high sensitivity and specificity. More often, it requires large and expensive laboratory instruments, which makes it difficult to conduct when the tests must be performed quickly at the point-of-care (POC). To increase portability and ease of use, we propose a portable diagnostic system based on a Raspberry Pi imaging sensor for the rapid detection of progesterone in milk samples. We designed, assembled, and tested a standalone portable diagnostic reader and validated it for progesterone detection against a standard ELISA assay using a commercial plate reader. The portable POC device yielded consistent results, regardless of differences in the cameras and flashlights between various smartphone devices. An Android application was built to provide front-end access to users, control the diagnostic reader, and display and store the progesterone measurement on the smartphone. The diagnostic reader takes images of the samples, reads the pixel values, processes the results, and presents the results on the handheld device. The proposed POC reader can perform to superior levels of performance as a plate reader, while adding the desirable qualities of portability and ease of use. PMID:28489036

GryphSens: A Smartphone-Based Portable Diagnostic Reader for the Rapid Detection of Progesterone in Milk.

PubMed

Jang, Hyunwook; Ahmed, Syed Rahin; Neethirajan, Suresh

2017-05-10

Enzyme-linked immunosorbent assay (ELISA) is a popular assay technique for the detection and quantification of various biological substances due its high sensitivity and specificity. More often, it requires large and expensive laboratory instruments, which makes it difficult to conduct when the tests must be performed quickly at the point-of-care (POC). To increase portability and ease of use, we propose a portable diagnostic system based on a Raspberry Pi imaging sensor for the rapid detection of progesterone in milk samples. We designed, assembled, and tested a standalone portable diagnostic reader and validated it for progesterone detection against a standard ELISA assay using a commercial plate reader. The portable POC device yielded consistent results, regardless of differences in the cameras and flashlights between various smartphone devices. An Android application was built to provide front-end access to users, control the diagnostic reader, and display and store the progesterone measurement on the smartphone. The diagnostic reader takes images of the samples, reads the pixel values, processes the results, and presents the results on the handheld device. The proposed POC reader can perform to superior levels of performance as a plate reader, while adding the desirable qualities of portability and ease of use.

Development of a personal dosimetry system based on optically stimulated luminescence of alpha-Al2O3:C for mixed radiation fields.

PubMed

Lee, S Y; Lee, K J

2001-04-01

To develop a personal optically stimulated luminescence (OSL) dosimetry system for mixed radiation fields using alpha-Al2O3:C, a discriminating badge filter system was designed by taking advantage of its optically stimulable properties and energy dependencies. This was done by designing a multi-element badge system for powder layered alpha-Al2O3:C material and an optical reader system based on high-intensity blue light-emitting diode (LED). The design of the multielement OSL dosimeter badge system developed allows the measurement of a personal dose equivalent value Hp(d) in mixed radiation fields of beta and gamma. Dosimetric properties of the personal OSL dosimeter badge system investigated here were the dose response, energy response and multi-readability. Based on the computational simulations and experiments of the proposed dosimeter design, it was demonstrated that a multi-element dosimeter system with an OSL technology based on alpha-Al2O3:C is suitable to obtain personal dose equivalent information in mixed radiation fields.

Time-resolved optically stimulated luminescence of Al2O3:C for ion beam therapy dosimetry

NASA Astrophysics Data System (ADS)

Yukihara, Eduardo G.; Doull, Brandon A.; Ahmed, Md; Brons, Stephan; Tessonnier, Thomas; Jäkel, Oliver; Greilich, Steffen

2015-09-01

The objective of this study was to characterize the time-resolved (TR) optically stimulated luminescence (OSL) from Al2O3:C detectors and investigate methodologies to improve the accuracy of these detectors in ion beam therapy dosimetry, addressing the reduction in relative response to high linear energy transfer (LET) particles common to solid-state detectors. Al2O3:C OSL detectors (OSLDs) were exposed to proton, 4He, 12C and 16O beams in 22 particle/energy combinations and read using a custom-built TR-OSL reader. The OSL response {{r}\\text{OSL}} , relative to 60Co gamma dose to water, and the ratio between the UV and blue OSL emission bands of Al2O3:C (UV/blue ratio) were determined as a function of the LET. Monte-Carlo simulations with the multi-purpose interaction and transport code FLUKA were used to estimate the absorbed doses and particle energy spectra in the different irradiation conditions. The OSL responses {{r}\\text{OSL}} varied from 0.980 (0.73 keV μm-1) to 0.288 (120.8 keV μm-1). The OSL UV/blue ratio varied by a factor of two in the investigated LET range, but the variation for 12C beams was only 11%. OSLDs were also irradiated at different depths of carbon ion spread-out Bragg peaks (SOBPs), where it was shown that doses could be obtained with an accuracy of  ±2.0% at the entrance channel and within the SOBP using correction factors calculated based on the OSL responses obtained in this study. The UV/blue ratio did not allow accurate estimation of the dose-averaged LET for 12C SOBPs, although the values obtained can be explained with the data obtained in this study and the additional information provided by the Monte-Carlo simulations. The results demonstrate that accurate OSLD dosimetry can be performed in ion beam therapy using appropriate corrections for the OSL response.

Characterization of OSL dosimeters for use in dose assessment in Computed Tomography procedures.

PubMed

Giansante, Louise; Santos, Josilene C; Umisedo, Nancy K; Terini, Ricardo A; Costa, Paulo R

2018-03-01

This study describes the characterization of an Al 2 O 3 :C OSLD (Landauer's Luxel™ tape) for dose evaluation in Computed Tomography. The irradiations were conducted using both a constant potential X-ray equipment and a 64-slice clinical CT scanner, and the readouts were performed using a Risø TL/OSL reader. The following aspects were studied: batch homogeneity, energy response, linearity of dose response, reproducibility, reusability, and effect of uncertainties with the normalization of OSL signals per their response to beta radiation. A group of 330 dosimeters from the 452 irradiated with the same dose presented OSL signals within the interval of 4.7% from the average. The dosimeters presented energy-dependent response in good agreement with results found in the literature. The air kerma response of the OSL signal showed a linear trend for both the constant potential X-ray device and the clinical CT scanner, with differences in their slopes of approximately 10%. Reproducibility, reusability, and effect of beta normalization were analyzed by separating 72 dosimeters in 3 groups. The results obtained in this study together with those of previous works indicate that this type of dosimeter is adequate for dose evaluation in CT clinical applications. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A reusable OSL-film for 2D radiotherapy dosimetry

NASA Astrophysics Data System (ADS)

Wouter, Crijns; Dirk, Vandenbroucke; Paul, Leblans; Tom, Depuydt

2017-11-01

Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N.V. produced a new experimental OSL-film for RT dosimetry. This film had a lower effective atomic number compared to the films used in radiology. Typical 2D dosimeter requirements such as uniformity, dose response, signal stability with time, and angular dependence were evaluated. Additionally, the impact of a possible residual energy dependence was assessed for the infield as well as the out-of-field region of both static beams and standard intensity modulated patterns (chair and pyramid). The OSL-film’s reusable nature allowed for a film specific absolute and linear calibration including a flood-field uniformity correction. The OSL-film was scanned with a CR-15X engine based reader using a strict timing (i.e. 4 min after ‘beam on’ or as soon as possible) to account for spontaneous recombination. The OSL-film had good basic response properties: non-uniformities  ⩽2.6%, a linear dose response (0-32 Gy), a linear signal decay (0.5% min-1) over the 20 min measured, and limited angular dependence  ⩽2.6%. Due to variations of the energy spectrum, larger dose differences were noted outside the central region of the homogenous phantom and outside both static and IMRT fields. However, the OSL-film’s measured dose differences of the IMRT patterns were lower than those of Gafchromic EBT measurements ([-1.6%, 2.1%] versus [-2.9%, 3.6%]). The current OSL-film could be used as a reusable high resolution dosimeter with read-out immediately after irradiation. Inside the (IMRT) treatment fields residual energy dependent effects were not observed. Novelty and significance: Implementing a reusable optical stimulated luminescence (OSL) film for radiotherapy dosimetry would enable user-friendly, sub(mm) resolution 2D dosimetry with instantaneous read-out. Radiology OSL-films have a strong energy dependent response which hampers accurate dosimetry. The current work reports measurements with a first 2D OSL-film tailored to the radiotherapy needs: including an improved water equivalent composition. The dosimeter adds the ability for sub-mm resolution repeated measurements to the portfolio of radiotherapy dosimetry.

A reusable OSL-film for 2D radiotherapy dosimetry.

PubMed

Wouter, Crijns; Dirk, Vandenbroucke; Paul, Leblans; Tom, Depuydt

2017-10-19

Optical stimulated luminescence (OSL) combines reusability, sub-mm resolution, and a linear dose response in a single radiation detection technology. Such a combination is currently lacking in radiotherapy dosimetry. But OSL-films have a strong energy dependent response to keV photons due to a relative high effective atomic number (Z eff ). The current work studied the applicability of a 2D OSL-film with a reduced Z eff as (IMRT/VMAT) dosimeter. Based on their commercial OSL-film experience, Agfa Healthcare N.V. produced a new experimental OSL-film for RT dosimetry. This film had a lower effective atomic number compared to the films used in radiology. Typical 2D dosimeter requirements such as uniformity, dose response, signal stability with time, and angular dependence were evaluated. Additionally, the impact of a possible residual energy dependence was assessed for the infield as well as the out-of-field region of both static beams and standard intensity modulated patterns (chair and pyramid). The OSL-film's reusable nature allowed for a film specific absolute and linear calibration including a flood-field uniformity correction. The OSL-film was scanned with a CR-15X engine based reader using a strict timing (i.e. 4 min after 'beam on' or as soon as possible) to account for spontaneous recombination. The OSL-film had good basic response properties: non-uniformities  ⩽2.6%, a linear dose response (0-32 Gy), a linear signal decay (0.5% min -1 ) over the 20 min measured, and limited angular dependence  ⩽2.6%. Due to variations of the energy spectrum, larger dose differences were noted outside the central region of the homogenous phantom and outside both static and IMRT fields. However, the OSL-film's measured dose differences of the IMRT patterns were lower than those of Gafchromic EBT measurements ([-1.6%, 2.1%] versus [-2.9%, 3.6%]). The current OSL-film could be used as a reusable high resolution dosimeter with read-out immediately after irradiation. Inside the (IMRT) treatment fields residual energy dependent effects were not observed. Novelty and significance: Implementing a reusable optical stimulated luminescence (OSL) film for radiotherapy dosimetry would enable user-friendly, sub(mm) resolution 2D dosimetry with instantaneous read-out. Radiology OSL-films have a strong energy dependent response which hampers accurate dosimetry. The current work reports measurements with a first 2D OSL-film tailored to the radiotherapy needs: including an improved water equivalent composition. The dosimeter adds the ability for sub-mm resolution repeated measurements to the portfolio of radiotherapy dosimetry.

An Efficient, Affordable Optically Stimulated Luminescent (OSL) Annealer.

PubMed

Abraham, Sara A; Frank, Samuel J; Kearfott, Kimberlee J

2017-07-01

Optically stimulated luminescent (OSL) dosimeters are devices used for measuring doses of ionizing radiation. Signal is stored within an OSL material so that when stimulated with light, light of a specific wavelength is emitted in proportion to the integrated ionizing radiation dose. Each interrogation of the material results in the loss of a small fraction of signal, thus allowing multiple interrogations leading to more accurate measurements of dose. In order to reuse a dosimeter, the residual signals from prior doses must be taken into account and subtracted from current readings, adding uncertainty to any future measurements. To reduce these errors when they become large, it is desirable to completely clear the stored signal or anneal the dosimeter. Traditionally, heating the material has accomplished this. In a commercially available dosimeter badge system, the OSL material Al2O3:C is incorporated into a plastic slide that would melt at the necessary high temperatures, which can reach 900 °C, required for annealing. Fortunately, due to the material's high sensitivity to light, OSLs can be optically annealed instead. In order to do this, an affordable OSL dosimeter annealer was designed with inexpensive, exchangeable blue, green, and white high intensity light-emitting diodes (LEDs). Several dosimeters were repeatedly annealed for recorded intervals and then read out. A single dosimeter was partially annealed through repeated interrogations with the LED array from a commercial reader. The signal loss due to the exposure to each light was analyzed to determine the practicality and efficiency of each color. The rate and extent of signal loss was dependent not only on the spectrum of annealing light but on the initial signal levels as well. These findings suggest that blue LEDs are the most promising for effective and rapid clearing of the OSL material Al2O3:C.

High-precision dosimetry for radiotherapy using the optically stimulated luminescence technique and thin Al2O3:C dosimeters.

PubMed

Yukihara, E G; Yoshimura, E M; Lindstrom, T D; Ahmad, S; Taylor, K K; Mardirossian, G

2005-12-07

The potential of using the optically stimulated luminescence (OSL) technique with aluminium oxide (Al(2)O(3):C) dosimeters for a precise and accurate estimation of absorbed doses delivered by high-energy photon beams was investigated. This study demonstrates the high reproducibility of the OSL measurements and presents a preliminary determination of the depth-dose curve in water for a 6 MV photon beam from a linear accelerator. The uncertainty of a single OSL measurement, estimated from the variance of a large sample of dosimeters irradiated with the same dose, was 0.7%. In the depth-dose curve obtained using the OSL technique, the difference between the measured and expected doses was < or =0.7% for depths between 1.5 and 10 cm, and 1.1% for a depth of 15 cm. The readout procedure includes a normalization of the response of the dosimeter with respect to a reference dose in order to eliminate variations in the dosimeter mass, dosimeter sensitivity, and the reader's sensitivity. This may be relevant for quality assurance programmes, since it simplifies the requirements in terms of personnel training to achieve the precision and accuracy necessary for radiotherapy applications. We concluded that the OSL technique has the potential to be reliably incorporated in quality assurance programmes and dose verification.

Determining the applicability of the Landauer nanoDot as a general public dosimeter in a research imaging facility.

PubMed

Charlton, Michael A; Thoreson, Kelly F; Cerecero, Jennifer A

2012-11-01

The Research Imaging Institute (RII) building at the University of Texas Health Science Center at San Antonio (UTHSCSA) houses two cyclotron particle accelerators, positron emission tomography (PET) machines, and a fluoroscopic unit. As part of the radiation protection program (RPP) and meeting the standard for achieving ALARA (as low as reasonably achievable), it is essential to minimize the ionizing radiation exposure to the general public through the use of controlled areas and area dose monitoring. Currently, thirty-four whole body Luxel+ dosimeters, manufactured by Landauer, are being used in various locations within the RII to monitor dose to the general public. The intent of this research was to determine if the nanoDot, a single point dosimeter, can be used as a general public dosimeter in a diagnostic facility. This was tested by first verifying characteristics of the nanoDot dosimeter including dose linearity, dose rate dependence, angular dependence, and energy dependence. Then, the response of the nanoDot dosimeter to the Luxel+ dosimeter when placed in a continuous, low dose environment was investigated. Finally, the nanoDot was checked for appropriate response in an acute, high dose environment. Based on the results, the current recommendation is that the nanoDot should not replace the Luxel+ dosimeter without further work to determine the energy spectra in the RII building and without considering the limitation of the microStar reader, portable on-site OSL reader, at doses below 0.1 mGy (10 mrad).

Luminescence signal profiling: a new proxy for sedimentologically "invisible" marine Mass Transport Deposits (MTDs)

NASA Astrophysics Data System (ADS)

López, Gloria I.; Bialik, Or; Waldmann, Nicolas

2017-04-01

When dealing with fine-grained, organic-rich, colour-monotone, underwater marine sediment cores retrieved from the continental shelf or slope, the initial visual impression, upon split-opening the vessels, is often of a "disappointing" homogeneous, monotonous, continuous archive. Only after thorough, micro- to macro-scale, multi-parameter investigations the sediment reveals its treasures, initially by performing some measurements on the intact core itself, hence depicting for the first time its contents, and subsequently by carrying out the destructive, multi-proxy sample-based analyses. Usually, routine Multi-Sensor Core Logger (MSCL) measurements of petrophysical parameters (e.g. magnetic susceptibility, density, P-Wave velocity) on un-split sediment cores are the first undertaken while still on-board in the field or back at the laboratory. Less often done, but equally valuable, are continuous X-Ray and CT scan imaging of the same intact archives. Upon splitting, routine granulometry, micro- and macro-fossil and invertebrate identification, total organic / inorganic carbon content (TOC / TIC), amid other analyses take place. The geochronology component is also established usually by AMS 14C on selected organic-rich units, and less common is Optically Stimulated Luminescence (OSL) dating used on the coarser-grained, siliciclastic layers. A relatively new tool used in Luminescence, the Portable OSL Reader, employed to rapidly assess the luminescence signal of untreated poly-mineral samples to assist with targeted field sampling for full OSL dating, was used for the first time in marine sediment cores as a novel petrophysical characterization tool with astonishing results. In this study, two 2 m-long underwater piston sediment cores recovered from 200 m depths on the continental shelf off-southern Israel, were subjected to pulsed-photon stimulation (PPSL) obtaining favourable luminescence signals along their entire lengths. Astoundingly, luminescence signals were obtained on both, already split-opened cores. Both cores depicted the monotonous characteristics of homogeneousness down-core as per most of the results obtained from the non-destructive and destructive tests. One of the cores showed several small higher energy events, including a Mass Transport Deposit (MTD) within its first 10 cm, only fully visible on the CT scan imaging, the PPSL profile and particle size distribution plot. This initial investigation demonstrates the feasibility and usefulness of luminescence profiling as a new sedimentological and petrophysical proxy to better visualize homogeneous yet complex, fine-grained, underwater archives. Moreover, it helps to understand the continuity of the stratigraphy and linearity of deposition of the sediment, besides assisting on the estimation of relative ages provided that good OSL ages are obtained throughout the recovered archive.

Cathodoluminescence and Thermoluminescence of Undoped LTB and LTB:A (A = Cu, Ag, Mn)

DTIC Science & Technology

2013-03-01

operated, tabletop instrument for thermoluminescent dosimetry (TLD) measurements seen in Figure 3-8. It reads one dosimeter per loading and...the more sophisticated Riso TL/ OSL reader that Brant used at the University of Cincinnati [9]. Figure 4-12: TL data for LTB: Ag irradiated with 5

Determination of multislice computed tomography dose index (CTDI) using optically stimulated luminescence technology.

PubMed

Ruan, Chun; Yukihara, Eduardo G; Clouse, William J; Gasparian, Patricia B R; Ahmad, Salahuddin

2010-07-01

The extensive use of multislice computed tomography (MSCT) and the associated increase in patient dose calls for an accurate dose evaluation technique. Optically stimulated luminescence (OSL) dosimetry provides a potential solution to the arising concerns over patient dose. This study was intended to evaluate the feasibility and accuracy of OSL dosimeter systems in the diagnostic CT x-ray beam energy range. MSCT dose profiles were measured by irradiating OSL strips placed inside the extended PMMA head and body phantoms at different scan conditions by varying kVp settings (100, 120, and 140 kVp) and collimated beam widths (5, 10, 20, and 40 mm). All scans in this study were performed using a GE Lightspeed VCT scanner in axial mode. The exposed strips were then read out using a custom-made OSL strip reader and corrected with field-specific conversion factors. Based on the corrected OSL dose profile, the CTDI(450-OSL) and CTDI(l00-OSL) were evaluated. CTDI(100-IC) was also obtained using a 100 mm long pencil ionization chamber for accuracy verification. CTDI(100-efficiency) can be further evaluated by calculating the ratio of CTDI(100-OSL) and CTDI(450-OSL), which was compared to results from previous studies as well. The OSL detectors were found to have good sensitivity and dose response over a wide range of diagnostic CT x-ray beam energy viz. the primary beam and the scatter tail section of the dose profile. The differences between CTDI100 values obtained using the OSL strips and those obtained with 100 mm long pencil ionization chamber were < +/- 5% for all scan conditions, indicating good accuracy of the OSL system. It was also found that the CTDI(100-efficiency) did not significantly change as the beam width increased and tube voltage changed. The average CTDI(100-efficiency) at the center of the head and body phantoms were 72.6% and 56.2%, respectively. The corresponding values for the periphery of the head and body phantoms were 85.0% and 81.7%. These results agreed very well with previous results from the literature using other detection techniques or Monte Carlo simulations. The LED-based OSL system can be an accurate alternative device for CT dose evaluations. CTDI100 measurement with the use of a 100 mm pencil ionization chamber substantially underestimates the CTDIinfinity value even with 5 mm collimated beam width. The established complete set of CTDI(100-efficiency) correction factors for various scan parameters allows for accurately estimating CTDIinfinity with the current use of pencil chamber and dose phantoms. Combined with the simple calibration, it gives this work great potential to be used not only in routine clinical quality assurance checks but also as a promising tool for patient organ dose assessment.

Retrospective dosimetry using OSL of tooth enamel and dental repair materials irradiated under wet and dry conditions.

PubMed

Geber-Bergstrand, Therése; Bernhardsson, Christian; Mattsson, Sören; Rääf, Christopher L

2012-11-01

Following a radiological or nuclear emergency event, there is a need for quick and reliable dose estimations of potentially exposed people. In situations where dosimeters are not readily available, the dose estimations must be carried out using alternative methods. In the present study, the optically stimulated luminescence (OSL) properties of tooth enamel and different dental repair materials have been examined. Specimens of the materials were exposed to gamma and beta radiation in different types of liquid environments to mimic the actual irradiation situation in the mouth. Measurements were taken using a Risø TL/OSL reader, and irradiations were made using a (90)Sr/(90)Y source and a linear accelerator (6 MV photons). Results show that the OSL signal from tooth enamel decreases substantially when the enamel is kept in a wet environment. Thus, tooth enamel is not reliable for retrospective dose assessment without further studies of the phenomenon. Dental repair materials, on the other hand, do not exhibit the same effect when exposed to liquids. In addition, dose-response and fading measurements of the dental repair materials show promising results, making these materials highly interesting for retrospective dosimetry. The minimum detectable dose for the dental repair materials has been estimated to be 20-185 mGy.

Germanium-doped optical fiber for real-time radiation dosimetry

NASA Astrophysics Data System (ADS)

Mizanur Rahman, A. K. M.; Zubair, H. T.; Begum, Mahfuza; Abdul-Rashid, H. A.; Yusoff, Z.; Ung, N. M.; Mat-Sharif, K. A.; Wan Abdullah, W. S.; Amouzad Mahdiraji, Ghafour; Amin, Y. M.; Maah, M. J.; Bradley, D. A.

2015-11-01

Over the past three decades growing demand for individualized in vivo dosimetry and subsequent dose verification has led to the pursuit of newer, novel and economically feasible materials for dosimeters. These materials are to facilitate features such as real-time sensing and fast readouts. In this paper, purposely composed SiO2:Ge optical fiber is presented as a suitable candidate for dosimetry. The optical fiber is meant to take advantage of the RL/OSL technique, providing both online remote monitoring of dose rate, and fast readouts for absorbed dose. A laboratory-assembled OSL reader has been used to acquire the RL/OSL response to LINAC irradiations (6 MV photons). The notable RL characteristics observed include constant level of luminescence for the same dose rate (providing better consistency compared to TLD-500), and linearity of response in the radiotherapy range (1 Gy/min to 6 Gy/min). The OSL curve was found to conform to an exponential decay characteristic (illumination with low LED source). The Ge doping resulted in an effective atomic number, Zeff, of 13.5 (within the bone equivalent range). The SiO2:Ge optical fiber sensor, with efficient coupling, can be a viable solution for in vivo dosimetry, besides a broad range of applications.

Optically stimulated luminescence in vivo dosimetry for radiotherapy: physical characterization and clinical measurements in (60)Co beams.

PubMed

Mrčela, I; Bokulić, T; Izewska, J; Budanec, M; Fröbe, A; Kusić, Z

2011-09-21

A commercial optically stimulated luminescence (OSL) dosimetry system was investigated for in vivo dosimetry in radiation therapy. Dosimetric characteristics of InLight dot dosimeters and a microStar reader (Landauer Inc.) were tested in (60)Co beams. The reading uncertainty of a single dosimeter was 0.6%. The reproducibility of a set of dosimeters after a single irradiation was 1.6%, while in repeated irradiations of the same dosimeters it was found to be 3.5%. When OSL dosimeters were optically bleached between exposures, the reproducibility of repeated measurements improved to 1.0%. Dosimeters were calibrated for the entrance dose measurements and a full set of correction factors was determined. A pilot patient study that followed phantom validation testing included more than 100 measured fields with a mean relative difference of the measured entrance dose from the expected dose of 0.8% and the standard deviation of 2.5%. In conclusion, these results demonstrate that OSL dot dosimeters represent a valid alternative to already established in vivo dosimetry systems.

Optically stimulated luminescence in vivo dosimetry for radiotherapy: physical characterization and clinical measurements in 60Co beams

NASA Astrophysics Data System (ADS)

Mrčela, I.; Bokulić, T.; Izewska, J.; Budanec, M.; Fröbe, A.; Kusić, Z.

2011-09-01

A commercial optically stimulated luminescence (OSL) dosimetry system was investigated for in vivo dosimetry in radiation therapy. Dosimetric characteristics of InLight dot dosimeters and a microStar reader (Landauer Inc.) were tested in 60Co beams. The reading uncertainty of a single dosimeter was 0.6%. The reproducibility of a set of dosimeters after a single irradiation was 1.6%, while in repeated irradiations of the same dosimeters it was found to be 3.5%. When OSL dosimeters were optically bleached between exposures, the reproducibility of repeated measurements improved to 1.0%. Dosimeters were calibrated for the entrance dose measurements and a full set of correction factors was determined. A pilot patient study that followed phantom validation testing included more than 100 measured fields with a mean relative difference of the measured entrance dose from the expected dose of 0.8% and the standard deviation of 2.5%. In conclusion, these results demonstrate that OSL dot dosimeters represent a valid alternative to already established in vivo dosimetry systems.

Optically Stimulated Luminescence Response to Ionizing Radiation of Red Bricks (SiO2, Al2O3, and Fe2O3) Used as Building Materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogard, James S; Espinosa Garcia, Guillermo

2007-01-01

Quartz is the most common mineral in our environment. It is found in granite, hydrothermal veins and volcanic rocks, as well as in sedimentary deposits derived from such solid materials. These sediments are also made into building materials, such as bricks and pottery. Thus the potential use of a dose reconstruction technique based on quartz grains is enormous, whether as a dating tool in archaeology and quaternary geology, or in nuclear accident dosimetry. This work describes the Optically Stimulated Luminescence (OSL) response of red brick to ionizing radiation. The bricks, from the state of Puebla, Mexico, represent another class ofmore » materials that can be used in retrospective dosimetry following nuclear or radiological incidents. The chemical composition of fifteen bricks (three samples from five different brick factories) was determined, using energy dispersive spectroscopy (EDS), be primarily SiO{sub 2}, Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} and is believed to be representative for this common building material. Individual aliquots from these bricks were powdered in agate mortars and thermally annealed. Replicate samples of the aliquots were then irradiated with beta particles from a sealed source of {sup 90}Sr/{sup 90}Y. The OSL response was measured with a Daybreak Model 2200 High-Capacity OSL Reader System. We present here for this material the characteristic OSL response to beta particles; the reproducibility of the OSL response; the linearity of the response in the dose range 0.47 Gy to 47 Gy; and the fading characteristics.« less

Proceedings of the 4th New World Luminescence Dating and Dosimetry Workshop, Denver, Colorado, May 31 June 2, 2006

USGS Publications Warehouse

Wise, Richard A.

2006-01-01

Introduction: Optically stimulated luminescence (OSL) is one of a class of measurements known as stimulated phenomena. Such phenomena may be stimulated thermally or optically and the reader is referred to works by Aitken (1998) and Botter-Jensen and others (2003) for more detail. In recent years OSL has become a popular procedure for the determination of environmental radiation doses absorbed by archeological and geological materials in an attempt to date these materials. The first OSL measurements on quartz and feldspar were made using an argon ion-laser (Huntley et al., 1985). However, the development of cheaper stimulation systems based first on filtered lamps and then on light- emitting diodes (LEDs) (Spooner, et al., 1990; Botter-Jensen, and others, 1999) has led to a massive expansion in OSL dating applications. The abstracts in this volume represent presentations from a workshop held in May-June 2006, at the Denver Federal Center, Denver, Colorado, in which OSL methodologies and applications were summarized and integrated to provide a current synthesis of the OSL science being applied throughout North America. The workshop, sponsored by the U.S. Geological Survey Crustal Imaging and Characterization Team and North Dakota State University, was open to all scientists interested in OSL dating techniques and radiation dosimetry. Participants included thirty-six research scientists and students in geology, archaeology, and physics from the U.S. Geological Survey, Los Alamos National Labs, Kentucky Geological Survey, eight universities in the United States, one university in Canada, one university in India, and Riso National Labs of Denmark. The workshop included two keynote speakers: Dr. Ashok Singhvi (Physical Research Laboratory, Ahmedabad, India) spoke on 'Some Unexplored Methodological Aspects and Some New Applications of Luminescence Dating,' while Dr. Jim Feathers (University of Seattle, WA) spoke on OSL Dating of Sediments From Paleoindian Sites in Brazil. The workshop encouraged everyone to interact more to develop a broader perspective on the types of research and the problems encountered when reporting OSL ages. This meeting follows the first North American Luminescence Dating Workshop held in Tulsa, OK, by Oklahoma State University (2001), in Albuquerque, NM, by Los Alamos National Labs (2002), and in Halifax, Nova Scotia, by Dalhousie University (2004, with a name change to New World Luminescence Dating Workshop). These workshops were interspersed with the international meetings on luminescence that were held in Reno, NV, (2002), and Cologne, Germany; (2005).

Novel versatile smart phone based Microplate readers for on-site diagnoses.

PubMed

Fu, Qiangqiang; Wu, Ze; Li, Xiuqing; Yao, Cuize; Yu, Shiting; Xiao, Wei; Tang, Yong

2016-07-15

Microplate readers are important diagnostic instruments, used intensively for various readout test kits (biochemical analysis kits and ELISA kits). However, due to their expensive and non-portability, commercial microplate readers are unavailable for home testing, community and rural hospitals, especially in developing countries. In this study, to provide a field-portable, cost-effective and versatile diagnostic tool, we reported a novel smart phone based microplate reader. The basic principle of this devise relies on a smart phone's optical sensor that measures transmitted light intensities of liquid samples. To prove the validity of these devises, developed smart phone based microplate readers were applied to readout results of various analytical targets. These targets included analanine aminotransferase (ALT; limit of detection (LOD) was 17.54 U/L), alkaline phosphatase (AKP; LOD was 15.56 U/L), creatinine (LOD was 1.35μM), bovine serum albumin (BSA; LOD was 0.0041mg/mL), prostate specific antigen (PSA; LOD was 0.76pg/mL), and ractopamine (Rac; LOD was 0.31ng/mL). The developed smart phone based microplate readers are versatile, portable, and inexpensive; they are unique because of their ability to perform under circumstances where resources and expertize are limited. Copyright © 2016 Elsevier B.V. All rights reserved.

An investigation into the feasibility of locating portable medical devices using radio frequency identification devices and technology.

PubMed

Britton, J

2007-01-01

Portable medical devices represent an important resource for assisting healthcare delivery. The movement of portable devices often results in them being unavailable when needed. Tracking equipment using radiofrequency identification technology/devices (RFID) may provide a promising solution to the problems encountered in locating portable equipment. An RFID technology trial was undertaken at Royal Alexandra Hospital, Paisley. This involved the temporary installation of three active readers and attaching actively transmitting radio frequency tags to different portable medical devices. The active readers and computer system were linked using a bespoke data network. Tags and readers from two separate manufacturers were tested. Reliability difficulties were encountered when testing the technology from the first manufacturer, probably due to the casing of the medical device interfering with the signal from the tag. Improved results were obtained when using equipment from the second manufacturer with an overall error rate of 12.3%. Tags from this manufacturer were specifically designed to overcome problems observed with the first system tested. Findings from this proof of concept trial suggest that RFID technology could be used to track the location of equipment in a hospital.

Microprocessor controlled portable TLD system

NASA Technical Reports Server (NTRS)

Apathy, I.; Deme, S.; Feher, I.

1996-01-01

An up-to-date microprocessor controlled thermoluminescence dosemeter (TLD) system for environmental and space dose measurements has been developed. The earlier version of the portable TLD system, Pille, was successfully used on Soviet orbital stations as well as on the US Space Shuttle, and for environmental monitoring. The new portable TLD system, Pille'95, consists of a reader and TL bulb dosemeters, and each dosemeter is provided with an EEPROM chip for automatic identification. The glow curve data are digitised and analysed by the program of the reader. The measured data and the identification number appear on the LED display of the reader. Up to several thousand measured data together with the glow curves can be stored on a removable flash memory card. The whole system is supplied either from built-in rechargeable batteries or from the mains of the space station.

SU-E-T-87: The Effect of Bleaching Wavelengths on the Regeneration of the Optically Stimulated Luminescence Signal of NanoDot Dosimeters Pre-Exposed to High-Doses.

PubMed

Omotayo, A; Cygler, J; Sawakuchi, G

2012-06-01

To investigate the effect of bleaching wavelengths on the regeneration of optically stimulated luminescence (OSL) signals in Al 2 O 3 :C nanoDot dosimeters pre-exposed to high doses. Regeneration is the increase in the OSL signal during storage of a bleached nanoDot that was previously pre-exposed to a high dose. This phenomenon affects the accuracy of a calibration protocol proposed by Jursinic 2010 (Med. Phys. 37:102) in which pre-exposure of nanoDots to a high-dose was used to minimize changes in the sensitivity of the detector as a function of accumulated dose. Al 2 O 3 :C OSLDs of the type nanoDot were used throughout this study. Readout was performed using the microStar reader. Bleaching of the OSLDs was performed with four 26 W fluorescent light bulbs in two modes: (i) directly under the lamps; and (ii) with the aid of a long-pass optical filter placed over the nanoDots, partially blocking wavelengths below 495 nm. Eighteen nanoDots were pre-exposed to 1 kGy dose. Then the pre-exposed nanoDots were bleached in two sets of 9 to very low residual OSL signals using bleaching modes (i) and (ii) for 12 h and 45 h, respectively. The nanoDots were then stored in dark and readout after various time intervals to monitor the regeneration of the OSL signal. We fitted the regeneration of the OSL signal using a saturation function and obtained rise-time values of 563 h and 630 h, for bleaching modes (i) and (ii), respectively. At the saturation level, the equivalent doses were about 1.18 Gy and 0.38 Gy for modes (i) and (ii), respectively. The regeneration rates of nanoDot OSLDs pre-exposed to high doses depend on the bleaching light wavelength used to reset the detectors. A bleaching source that has a low component of wavelengths below 495 nm can minimize the regeneration of the OSL signal. Natural Sciences and Engineering Research Council of Canada. © 2012 American Association of Physicists in Medicine.

Response of optically stimulated luminescence dosimeters subjected to X-rays in diagnostic energy range

NASA Astrophysics Data System (ADS)

Musa, Y.; Hashim, S.; Karim, M. K. A.; Bakar, K. A.; Ang, W. C.; Salehhon, N.

2017-05-01

The use of optically stimulated luminescence (OSL) for dosimetry applications has recently increased considerably due to availability of commercial OSL dosimeters (nanoDots) for clinical use. The OSL dosimeter has a great potential to be used in clinical dosimetry because of its prevailing advantages in both handling and application. However, utilising nanoDot OSLDs for dose measurement in diagnostic radiology can only be guaranteed when the performance and characteristics of the dosimeters are apposite. In the present work, we examined the response of commercially available nanoDot OSLD (Al2O3:C) subjected to X-rays in general radiography. The nanoDots response with respect to reproducibility, dose linearity and signal depletion were analysed using microStar reader (Landauer, Inc., Glenwood, IL). Irradiations were performed free-in-air using 70, 80 and 120 kV tube voltages and tube currents ranging from 10 - 100 mAs. The results showed that the nanoDots exhibit good linearity and reproducibility when subjected to diagnostic X-rays, with coefficient of variations (CV) ranging between 2.3% to 3.5% representing a good reproducibility. The results also indicated average of 1% signal reduction per readout. Hence, the nanoDots showed a promising potential for dose measurement in general X-ray procedure.

Investigation of the response characteristics of OSL albedo neutron dosimeters in a 241AmBe reference neutron field

NASA Astrophysics Data System (ADS)

Liamsuwan, T.; Wonglee, S.; Channuie, J.; Esoa, J.; Monthonwattana, S.

2017-06-01

The objective of this work was to systematically investigate the response characteristics of optically stimulated luminescence Albedo neutron (OSLN) dosimeters to ensure reliable personal dosimetry service provided by Thailand Institute of Nuclear Technology (TINT). Several batches of InLight® OSLN dosimeters were irradiated in a reference neutron field generated by the in-house 241AmBe neutron irradiator. The OSL signals were typically measured 24 hours after irradiation using the InLight® Auto 200 Reader. Based on known values of delivered neutron dose equivalent, the reading correction factor to be used by the reader was evaluated. Subsequently, batch homogeneity, dose linearity, lower limit of detection and fading of the OSLN dosimeters were examined. Batch homogeneity was evaluated to be 0.12 ± 0.05. The neutron dose response exhibited a linear relationship (R2=0.9974) within the detectable neutron dose equivalent range under test (0.4-3 mSv). For this neutron field, the lower limit of detection was between 0.2 and 0.4 mSv. Over different post-irradiation storage times of up to 180 days, the readings fluctuated within ±5%. Personal dosimetry based on the investigated OSLN dosimeter is considered to be reliable under similar neutron exposure conditions, i.e. similar neutron energy spectra and dose equivalent values.

The effect of different bleaching wavelengths on the sensitivity of Al{sub 2}O{sub 3}:C optically stimulated luminescence detectors (OSLDs) exposed to 6 MV photon beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omotayo, Azeez A.; Cygler, Joanna E.; Sawakuchi, Gabriel O.

2012-09-15

Purpose: To determine the effect of different bleaching wavelengths on the response of Al{sub 2}O{sub 3}:C optically stimulated luminescence detectors (OSLDs) exposed to accumulated doses of 6 MV photon beams. Methods: In this study the authors used nanoDot OSLDs readout with a MicroStar reader. The authors first characterized the dose-response, fading, and OSL signal loss of OSLDs exposed to doses from 0.5 to 10 Gy. To determine the effect of different bleaching wavelengths on the OSLDs' response, the authors optically treated the OSLDs with 26 W fluorescent lamps in two modes: (i) directly under the lamps for 10, 120, andmore » 600 min and (ii) with a long-pass filter for 55, 600, and 2000 min. Changes in the OSLDs' sensitivity were determined for an irradiation-readout-bleaching-readout cycle after irradiations with 1 and 10 Gy dose fractions. Results: The OSLDs presented supralinearity for doses of 2 Gy and above. The signal loss rates for sequential readouts were (0.287 {+-} 0.007)% per readout in the reader's strong-stimulation mode, and (0.019 {+-} 0.002)% and (0.035 {+-} 0.007)% per readout for doses of 0.2 and 10 Gy, respectively, in the reader's weak-stimulation mode. Fading half-life values ranged from (0.98 {+-} 0.14) min to (1.77 {+-} 0.24) min and fading showed dose dependence for the first 10-min interval. For 10 and 55 min bleaching using modes (i) and (ii), the OSL signal increased 14% for an accumulated dose of 7 Gy (1 Gy fractions). For OSLDs exposed to 10 Gy fractions, the OSL signal increased 30% and 25% for bleaching modes (i) and (ii) and accumulated dose of 70 Gy, respectively. For 120 and 600 min bleaching using modes (i) and (ii), the OSL signal increased 2.7% and 1.5% for an accumulated dose of 7 Gy (1 Gy fractions), respectively. For 10 Gy fractions, the signal increased 14% for bleaching mode (i) (120 min bleaching) and decreased 1.3% for bleaching mode (ii) (600 min bleaching) for an accumulated dose of 70 Gy. For 600 and 2000 min bleaching using modes (i) and (ii), the signal increased 2.3% and 1.8% for an accumulated dose of 7 Gy (1 Gy fractions), respectively. For 10 Gy fractions, the signal increased 10% for mode (i) (600 min bleaching) and decreased 2.5% for mode (ii) (2000 min bleaching) for an accumulated dose of 70 Gy. Conclusions: The dose-response of nanoDot OSLDs read using the MicroStar reader presented supralinearity for doses of 2 Gy and above. The signal loss as a function of sequential readouts depended on dose. Fading also depended on dose for the first 10-min interval. For dose fractions of 1 and 10 Gy, OSLDs may be reused within 3% and 5% accuracies up to the maximum accumulated dose of 7 and 70 Gy investigated in this study, respectively. These accuracies were obtained after the OSLDs were bleached with a light source with wavelengths above about 495 nm. The authors also concluded that changes in sensitivity of OSLDs depended on bleaching time, accumulated dose, and wavelength spectrum of the bleaching source.« less

Ultra low-cost, portable smartphone optosensors for mobile point-of-care diagnostics

NASA Astrophysics Data System (ADS)

Wang, Li-Ju; Chang, Yu-Chung; Sun, Rongrong; Li, Lei

2018-02-01

Smartphone optosensors with integrated optical components make mobile point-of-care (MPoC) diagnostics be done near patients' side. It'll especially have a significant impact on healthcare delivery in rural or remote areas. Current FDA-approved PoC devices achieving clinical level are still at high cost and not affordable in rural hospitals. We present a series of ultra low-cost smartphone optical sensing devices for mobile point-of-care diagnosis. Aiming different targeting analytes and sensing mechanisms, we developed custom required optical components for each smartphone optosensros. These optical devices include spectrum readers, colorimetric readers for microplate, lateral flow device readers, and chemiluminescence readers. By integrating our unique designed optical components into smartphone optosening platform, the anlaytes can be precisely detected. Clinical testing results show the clinical usability of our smartphone optosensors. Ultra low-cost portable smartphone optosensors are affordable for rural/remote doctors.

A smartphone colorimetric reader integrated with an ambient light sensor and a 3D printed attachment for on-site detection of zearalenone.

PubMed

Chen, Yuan; Fu, Qiangqiang; Li, Dagang; Xie, Jun; Ke, Dongxu; Song, Qifang; Tang, Yong; Wang, Hong

2017-11-01

Smartphone biosensors could be cost-effective, portable instruments to be used for the readout of liquid colorimetric assays. However, current reported smartphone colorimetric readers have relied on photos of liquid assays captured using a camera, and then analyzed using software programs. This approach results in a relatively low accuracy and low generality. In this work, we reported a novel smartphone colorimetric reader that has been integrated with an ambient light sensor and a 3D printed attachment for the readout of liquid colorimetric assays. The portable and low-cost ($0.15) reader utilized a simplified electronic and light path design. Furthermore, our reported smartphone colorimetric reader can be compatible with different smartphones. As a proof of principle, the utility of this device was demonstrated using it in conjunction with an enzyme-linked immunosorbent assay to detect zearalenone. Results were consistent with those obtained using a professional microplate reader. The developed smartphone colorimetric reader was capable of providing scalable, cost-effective, and accurate results for liquid colorimetric assays that related to clinical diagnoses, environment pollution, and food testing. Graphical abstract A novel smartphone colorimetric reader that has been integrated with an ambient light sensor and a 3D printed attachment for the readout of liquid colorimetric assays.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thompson, Deanna Lynn; Coleman, Matthew A; Lane, Stephen M

A hand-held portable microarray reader for biodetection includes a microarray reader engineered to be small enough for portable applications. The invention includes a high-powered light-emitting diode that emits excitation light, an excitation filter positioned to receive the excitation light, a slide, a slide holder assembly for positioning the slide to receive the excitation light from the excitation filter, an emission filter positioned to receive the excitation light from the slide, a lens positioned to receive the excitation light from the emission filter, and a CCD camera positioned to receive the excitation light from the lens.

Exploring e-readers to support clinical medical education: two case studies*†

PubMed Central

von Isenburg, Megan

2011-01-01

Question: Can e-readers loaded with medical textbooks and other relevant material benefit medical students, residents, and preceptors in clinical settings? Settings: The settings are North Carolina community clinics served by Duke University Medical Center and St. Joseph's Hospital in Bryan, Texas, and Scott and White Memorial Hospital in Temple, Texas. Methods: Duke University: Twenty second-year medical students and fourteen family medicine clerkship preceptors used Kindle e-readers in clinics during eight months of rotations. Students and preceptors provided feedback through an anonymous online survey. Texas A&M University: Nine fourth-year medical students in an elective compared medical textbooks in print, online, and on a Kindle. Six residents at a local hospital completed an anonymous online survey after a three-week loan of a Kindle loaded with medical textbooks. Results: The e-reader's major advantages in clinical settings are portability and searchability. The selected e-reader's limitations include connection speed, navigation, and display. User preferences varied, but online resources were preferred. Participants suggested additional uses for Kindles in medical education. Conclusions: The selected e-reader's limitations may be resolved with further development of the device. Investigation of other e-readers is needed. Criteria for evaluating e-readers in clinical settings should include portability, searchability, speed, navigation, and display. Research comparing e-readers and mobile devices in clinical education is also warranted. PMID:21464848

McGill Library Makes E-Books Portable: E-Reader Loan Service in a Canadian Academic Library

ERIC Educational Resources Information Center

Savova, Maria; Garsia, Matthew

2012-01-01

E-readers are increasingly popular personal devices, but can they be effectively used for the needs of academic libraries' clients? This paper employs an evidence-based approach that examines the role and efficacy of implementing an E-reader Loan Service at McGill University Library. Suggestions are offered as to what lending model and device…

Development of OCR system for portable passport and visa reader

NASA Astrophysics Data System (ADS)

Visilter, Yury V.; Zheltov, Sergey Y.; Lukin, Anton A.

1999-01-01

The modern passport and visa documents include special machine-readable zones satisfied the ICAO standards. This allows to develop the special passport and visa automatic readers. However, there are some special problems in such OCR systems: low resolution of character images captured by CCD-camera (down to 150 dpi), essential shifts and slopes (up to 10 degrees), rich paper texture under the character symbols, non-homogeneous illumination. This paper presents the structure and some special aspects of OCR system for portable passport and visa reader. In our approach the binarization procedure is performed after the segmentation step, and it is applied to the each character site separately. Character recognition procedure uses the structural information of machine-readable zone. Special algorithms are developed for machine-readable zone extraction and character segmentation.

Automated Low-Cost Smartphone-Based Lateral Flow Saliva Test Reader for Drugs-of-Abuse Detection.

PubMed

Carrio, Adrian; Sampedro, Carlos; Sanchez-Lopez, Jose Luis; Pimienta, Miguel; Campoy, Pascual

2015-11-24

Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. While automated test readers providing a result-consistent solution are widely available, they usually lack portability. In this paper, we present a smartphone-based automated reader for drug-of-abuse lateral flow assay tests, consisting of an inexpensive light box and a smartphone device. Test images captured with the smartphone camera are processed in the device using computer vision and machine learning techniques to perform automatic extraction of the results. A deep validation of the system has been carried out showing the high accuracy of the system. The proposed approach, applicable to any line-based or color-based lateral flow test in the market, effectively reduces the manufacturing costs of the reader and makes it portable and massively available while providing accurate, reliable results.

Characterization of Al2O3 optically stimulated luminescence films for 2D dosimetry using a 6 MV photon beam

NASA Astrophysics Data System (ADS)

Ahmed, M. F.; Shrestha, N.; Schnell, E.; Ahmad, S.; Akselrod, M. S.; Yukihara, E. G.

2016-11-01

This work evaluates the dosimetric properties of newly developed optically stimulated luminescence (OSL) films, fabricated with either Al2O3:C or Al2O3:C,Mg, using a prototype laser scanning reader, a developed image reconstruction algorithm, and a 6 MV therapeutic photon beam. Packages containing OSL films (Al2O3:C and Al2O3:C,Mg) and a radiochromic film (Gafchromic EBT3) were irradiated using a 6 MV photon beam using different doses, field sizes, with and without wedge filter. Dependence on film orientation of the OSL system was also tested. Diode-array (MapCHECK) and ionization chamber measurements were performed for comparison. The OSLD film doses agreed with the MapCHECK and ionization chamber data within the experimental uncertainties (<2% at 1.5 Gy). The system background and minimum detectable dose (MDD) were  <0.5 mGy, and the dose response was approximately linear from the MDD up to a few grays (the linearity correction was  <10% up to ~2-4 Gy), with no saturation up to 30 Gy. The dose profiles agreed with those obtained using EBT3 films (analyzed using the triple channel method) in the high dose regions of the images. In the low dose regions, the dose profiles from the OSLD films were more reproducible than those from the EBT3 films. We also demonstrated that the OSL film data are independent on scan orientation and field size over the investigated range. The results demonstrate the potential of OSLD films for 2D dosimetry, particularly for the characterization of small fields, due to their wide dynamic range, linear response, resolution and dosimetric properties. The negligible background and potential simple calibration make these OSLD films suitable for remote audits. The characterization presented here may motivate further commercial development of a 2D dosimetry system based on the OSL from Al2O3:C or Al2O3:C,Mg.

Automated Low-Cost Smartphone-Based Lateral Flow Saliva Test Reader for Drugs-of-Abuse Detection

PubMed Central

Carrio, Adrian; Sampedro, Carlos; Sanchez-Lopez, Jose Luis; Pimienta, Miguel; Campoy, Pascual

2015-01-01

Lateral flow assay tests are nowadays becoming powerful, low-cost diagnostic tools. Obtaining a result is usually subject to visual interpretation of colored areas on the test by a human operator, introducing subjectivity and the possibility of errors in the extraction of the results. While automated test readers providing a result-consistent solution are widely available, they usually lack portability. In this paper, we present a smartphone-based automated reader for drug-of-abuse lateral flow assay tests, consisting of an inexpensive light box and a smartphone device. Test images captured with the smartphone camera are processed in the device using computer vision and machine learning techniques to perform automatic extraction of the results. A deep validation of the system has been carried out showing the high accuracy of the system. The proposed approach, applicable to any line-based or color-based lateral flow test in the market, effectively reduces the manufacturing costs of the reader and makes it portable and massively available while providing accurate, reliable results. PMID:26610513

Simultaneous Quantitative Detection of Helicobacter Pylori Based on a Rapid and Sensitive Testing Platform using Quantum Dots-Labeled Immunochromatiographic Test Strips

NASA Astrophysics Data System (ADS)

Zheng, Yu; Wang, Kan; Zhang, Jingjing; Qin, Weijian; Yan, Xinyu; Shen, Guangxia; Gao, Guo; Pan, Fei; Cui, Daxiang

2016-02-01

Quantum dots-labeled urea-enzyme antibody-based rapid immunochromatographic test strips have been developed as quantitative fluorescence point-of-care tests (POCTs) to detect helicobacter pylori. Presented in this study is a new test strip reader designed to run on tablet personal computers (PCs), which is portable for outdoor detection even without an alternating current (AC) power supply. A Wi-Fi module was integrated into the reader to improve its portability. Patient information was loaded by a barcode scanner, and an application designed to run on tablet PCs was developed to handle the acquired images. A vision algorithm called Kmeans was used for picture processing. Different concentrations of various human blood samples were tested to evaluate the stability and accuracy of the fabricated device. Results demonstrate that the reader can provide an easy, rapid, simultaneous, quantitative detection for helicobacter pylori. The proposed test strip reader has a lighter weight than existing detection readers, and it can run for long durations without an AC power supply, thus verifying that it possesses advantages for outdoor detection. Given its fast detection speed and high accuracy, the proposed reader combined with quantum dots-labeled test strips is suitable for POCTs and owns great potential in applications such as screening patients with infection of helicobacter pylori, etc. in near future.

TL-OSL correlation studies of LiMgPO4:Tb,B dosimetric phosphor

NASA Astrophysics Data System (ADS)

Singh, A. K.; Menon, S. N.; Dhabekar, Bhushan; Kadam, Sonal; Chougaonkar, M. P.; Mayya, Y. S.

2012-03-01

The recently synthesized LiMgPO4:Tb,B (LMP) is a highly sensitive Optically Stimulated Luminescence (OSL) phosphor for dosimetric applications. Studies were carried out to assess the correlation between thermoluminescence (TL) and OSL of this phosphor. Measurements like Residual TL (R-TL), Continuous Wave OSL (CW-OSL) and Linearly Modulated OSL (LM-OSL) of LMP were carried out and various curves thus obtained were de-convolved using Computerized Curve Deconvolution (CCD) program. The deconvolution of CW-OSL and LM-OSL curves showed five different first order components in LMP. It was observed that OSL signal of LMP has its origin from five traps having different photo-ionization cross-sections. Same traps were found to be responsible for both TL and OSL in this phosphor. Bleaching decay rates were calculated for each R-TL glow peaks and compared with the decay rates of individual OSL components. The value of decay rates of R-TL and OSL matches well. Experimental verification of presence of individual OSL components using tbleach-tmax method was carried out.

Enabling Handicapped Nonreaders to Independently Obtain Information: Initial Development of an Inexpensive Bar Code Reader System.

ERIC Educational Resources Information Center

VanBiervliet, Alan

A project to develop and evaluate a bar code reader system as a self-directed information and instructional aid for handicapped nonreaders is described. The bar code technology involves passing a light sensitive pen or laser over a printed code with bars which correspond to coded numbers. A system would consist of a portable device which could…

Ultra-low current biosensor output detection using portable electronic reader

NASA Astrophysics Data System (ADS)

Yahaya, N. A. N.; Rajapaksha, R. D. A. A.; Uda, M. N. Afnan; Hashim, U.

2017-09-01

Generally, the electrical biosensor usually shows extremely low current signal output around pico ampere to microampere range. In this research, electronic reader with amplifier has been demonstrated to detect ultra low current via the biosensor. The operational amplifier Burr-Brown OPA 128 and Arduino Uno board were used to construct the portable electronic reader. There are two cascaded inverting amplifier were used to detect ultra low current through the biosensor from pico amperes (pA) to nano amperes ranges (nA). A small known input current was form by applying variable voltage between 0.1V to 5.0V across a 5GΩ high resistor to check the amplifier circuit. The amplifier operation was measured with the high impedance current source and has been compared with the theoretical measurement. The Arduino Uno was used to convert the analog signal to digital signal and process the data to display on reader screen. In this project, Proteus software was used to design and test the circuit. Then it was implemented together with Arduino Uno board. Arduino board was programmed using C programming language to make whole circuit communicate each order. The current was measured then it shows a small difference values compared to theoretical values, which is approximately 14pA.

Portable Immune-Assessment System

NASA Technical Reports Server (NTRS)

Pierson, Duane L.; Stowe, Raymond P.; Mishra, Saroj K.

1995-01-01

Portable immune-assessment system developed for use in rapidly identifying infections or contaminated environment. System combines few specific fluorescent reagents for identifying immune-cell dysfunction, toxic substances, buildup of microbial antigens or microbial growth, and potential identification of pathogenic microorganisms using fluorescent microplate reader linked to laptop computer. By using few specific dyes for cell metabolism, DNA/RNA conjugation, specific enzyme activity, or cell constituents, one makes immediate, onsite determination of person's health or of contamination of environment.

The Use of eReaders in the Classroom and at Home to Help Third-Grade Students Improve Their Reading and English/Language Arts Standardized Test Scores

ERIC Educational Resources Information Center

Union, Craig D.; Union, Lori Walker; Green, Tim D.

2015-01-01

This study explored the effects of a portable technology intervention, the Nook Simple Touch eReader, on student performance in Reading and English/Language Arts when included as an integral part of the teaching and learning process in an elementary third-grade classroom. This study used the participating students' end-of-year second-grade scores…

Component resolved bleaching study in natural calcium fluoride using CW-OSL, LM-OSL and residual TL glow curves after bleaching.

PubMed

Angeli, Vasiliki; Polymeris, George S; Sfampa, Ioanna K; Tsirliganis, Nestor C; Kitis, George

2017-04-01

Natural calcium fluoride has been commonly used as thermoluminescence (TL) dosimeter due to its high luminescence intensity. The aim of this work includes attempting a correlation between specific TL glow curves after bleaching and components of linearly modulated optically stimulated luminescence (LM-OSL) as well as continuous wave OSL (CW-OSL). A component resolved analysis was applied to both integrated intensity of the RTL glow curves and all OSL decay curves, by using a Computerized Glow-Curve De-convolution (CGCD) procedure. All CW-OSL and LM-OSL components are correlated to the decay components of the integrated RTL signal, apart from two RTL components which cannot be directly correlated with either LM-OSL or CW-OSL component. The unique, stringent criterion for this correlation deals with the value of the decay constant λ of each bleaching component. There is only one, unique bleaching component present in all three luminescence entities which were the subject of the present study, indicating that each TL trap yields at least three different bleaching components; different TL traps can indicate bleaching components with similar values. According to the data of the present work each RTL bleaching component receives electrons from at least two peaks. The results of the present study strongly suggest that the traps that contribute to TL and OSL are the same. Copyright © 2017 Elsevier Ltd. All rights reserved.

Setting Age Limits for TT-OSL Dating - the Local Effect

NASA Astrophysics Data System (ADS)

Faershtein, G.; Porat, N.; Guralnik, B.; Matmon, A.

2017-12-01

Luminescence dating techniques, especially Optically Stimulated Luminescence (OSL) on quartz, are widely used for dating middle Pleistocene to late Holocene sediments from different geological settings. The dating limit of a particular luminescence method depends on signal saturation and its thermal stability. The OSL signal saturates at doses of 200 Gy, equivalent to ages of 150-300 ka. Thermally Transferred OSL (TT-OSL) is a developmental technique, which potentially extends the luminescence dating range up to 1000 ka. For the Chinese Loess Plateau, experiments have shown that the natural TT-OSL signal saturates at 2200 Gy (Chapot et al., 2016). Regarding thermal stability, different studies report a wide range of estimates (0.24-861 Ma), suggesting that the thermal lifetime of TT-OSL is (i) currently poorly constrained, and (ii) may vary both by sample and region. Here, we investigated the dating limit of TT-OSL, using quartz of Nilotic origin (Israel), obtained from two sediment sections of similar depth but different dose rates. Natural dose response curves (DRC) of the TT-OSL signal were constructed for each section separately. In both sections, luminescence intensity grows sub-linearly up to 450 Gy, beyond which it remains constant with depth. The absence of equivalent doses (De) over 600 Gy, at both sections (as well as elsewhere regionally), suggest that TT-OSL signal saturation may be an intrinsic property, related to quartz provenance, and independent of the specific ionizing dose rate at each section. The thermal stability of TT-OSL was investigated on a modern sample from one section, using a combination of analytical techniques (varying heating rates, and isothermal storage). The obtained TT-OSL lifetimes range between 105-107 ka, and reinforce a significant inter sample variability. A synthesis of our results suggests that TT-OSL ages of Nilotic quartz derived from De values over 450 Gy, are likely underestimates, and should be treated as minimum ages. The limiting value of 600 Gy for local quartz TT-OSL is likely representative of a steady-state between TT-OSL trap filling due to ionizing radiation, and the concurrent thermal empting of these traps.

Development of europium doped BaSO4 TL OSL dual phosphor for radiation dosimetry applications

NASA Astrophysics Data System (ADS)

Patle, Anita; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

2015-08-01

This paper presents the results on the preparation and characterization of Europium-doped Barium sulfate (BaSO4: Eu) TL /OSL dual phosphor. The OSL sensitivity was found to be 11% of the commercially available Al2O3: C, using area integration method. The sample also shows good TL sensitivity and the dosimetric peak appears around 190°C with a shoulder at 282°C. After OSL readout, No change in the TL glow curve is observed. Since the observed TL peaks are not responsible for the observed OSL, good OSL as well as TL sensitivity and low fading will make this phosphor suitable for applications in radiation dosimetry using OSL as well as TL.

Electrophoretic display technologies for e-book readers: system integration aspects

NASA Astrophysics Data System (ADS)

Gentric, Philippe

2011-03-01

Emerging screen technologies, such as Electrophoretic Displays (EPD) used in E-book Readers, are changing product power requirements due to their advantageous properties such as bi-stability (effective "zero power" static display) and reflective mode of operation (no backlight). We will first review the emerging screen technologies under the angle of system and IC design impact. We will explain power management consequences for IC design, with a focus on Application Engine SOCs for the wireless/portable markets.

Development of europium doped BaSO{sub 4} TL OSL dual phosphor for radiation dosimetry applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patle, Anita, E-mail: patle.anita25@gmail.com; Patil, R. R.; Kulkarni, M. S.

This paper presents the results on the preparation and characterization of Europium-doped Barium sulfate (BaSO{sub 4}: Eu) TL /OSL dual phosphor. The OSL sensitivity was found to be 11% of the commercially available Al{sub 2}O{sub 3}: C, using area integration method. The sample also shows good TL sensitivity and the dosimetric peak appears around 190°C with a shoulder at 282°C. After OSL readout, No change in the TL glow curve is observed. Since the observed TL peaks are not responsible for the observed OSL, good OSL as well as TL sensitivity and low fading will make this phosphor suitable formore » applications in radiation dosimetry using OSL as well as TL.« less

Experimental features of natural thermally assisted OSL (NTA-OSL) signal in various quartz samples; preliminary results

NASA Astrophysics Data System (ADS)

Polymeris, George S.; Şahiner, Eren; Meriç, Niyazi; Kitis, George

2015-04-01

The access to the OSL signals from very deep traps is achieved by an alternative experimental method which comprises combined action of thermal and optical stimulation, termed as thermally assisted OSL (TA-OSL). This experimental technique was suggested in order to not only measure the signal of the deep traps without heating the sample to temperatures greater than 500 °C, but also use the former for dosimetry purposes as well, due to exhibiting a number of interesting properties which could be effectively used towards dosimetry purposes, especially for large accumulated artificial doses. The present study provides for the first time in the literature with preliminary results towards the feasibility study of the naturally occurring TA-OSL signal in coarse grains of natural quartz towards its effective application to geological dating. The samples subjected to the present study were collected from fault lines in Kütahya-Simav, Western Anatolia Region, Turkey; independent luminescence approaches yielded an equivalent dose larger than 100 Gy. Several experimental luminescence features were studied, such as sensitivity, reproducibility, TA-OSL curve shape as well as the correlation between NTA-OSL and NTL/NOSL. Nevertheless, special emphasis was addressed towards optimizing the measuring conditions of the TA-OSL signal. The high intensity of the OSL signal confirms the existence of a transfer phenomenon from deep electron traps. The increase of the integrated TA-OSL signal as a function of temperature is monitored for temperatures up to 180 °C, indicating the later as the most effective stimulation temperature. At all temperatures of the studied temperature range between 75 and 260 °C, the shape of the signal resembles much the shape of a typical CW-OSL curve. However, a long-lived, residual NTA-OSL component was monitored after the primary, initial NTA-OSL measured at 180 °C; the intensity of this component increases with increasing stimulation temperature. The prevalence of these luminescent features was investigated, while the implications on dating applications of these features were also discussed.

Deconvolution Method on OSL Curves from ZrO2 Irradiated by Beta and UV Radiations

NASA Astrophysics Data System (ADS)

Rivera, T.; Kitis, G.; Azorín, J.; Furetta, C.

This paper reports the optically stimulated luminescent (OSL) response of ZrO2 to beta and ultraviolet radiations in order to investigate the potential use of this material as a radiation dosimeter. The experimentally obtained OSL decay curves were analyzed using the computerized curve de-convolution (CCD) method. It was found that the OSL curve structure, for the short (practical) illumination time used, consists of three first order components. The individual OSL dose response behavior of each component was found. The values of the time at the OSL peak maximum and the decay constant of each component were also estimated.

Apparatus And Method For Osl-Based, Remote Radiation Monitoring And Spectrometry

DOEpatents

Miller, Steven D.; Smith, Leon Eric; Skorpik, James R.

2006-03-07

Compact, OSL-based devices for long-term, unattended radiation detection and spectroscopy are provided. In addition, a method for extracting spectroscopic information from these devices is taught. The devices can comprise OSL pixels and at least one radiation filter surrounding at least a portion of the OSL pixels. The filter can modulate an incident radiation flux. The devices can further comprise a light source and a detector, both proximally located to the OSL pixels, as well as a power source and a wireless communication device, each operably connected to the light source and the detector. Power consumption of the device ranges from ultra-low to zero. The OSL pixels can retain data regarding incident radiation events as trapped charges. The data can be extracted wirelessly or manually. The method for extracting spectroscopic data comprises optically stimulating the exposed OSL pixels, detecting a readout luminescence, and reconstructing an incident-energy spectrum from the luminescence.

Apparatus and method for OSL-based, remote radiation monitoring and spectrometry

DOEpatents

Smith, Leon Eric [Richland, WA; Miller, Steven D [Richland, WA; Bowyer, Theodore W [Oakton, VA

2008-05-20

Compact, OSL-based devices for long-term, unattended radiation detection and spectroscopy are provided. In addition, a method for extracting spectroscopic information from these devices is taught. The devices can comprise OSL pixels and at least one radiation filter surrounding at least a portion of the OSL pixels. The filter can modulate an incident radiation flux. The devices can further comprise a light source and a detector, both proximally located to the OSL pixels, as well as a power source and a wireless communication device, each operably connected to the light source and the detector. Power consumption of the device ranges from ultra-low to zero. The OSL pixels can retain data regarding incident radiation events as trapped charges. The data can be extracted wirelessly or manually. The method for extracting spectroscopic data comprises optically stimulating the exposed OSL pixels, detecting a readout luminescence, and reconstructing an incident-energy spectrum from the luminescence.

A Novel Marking Reader for Progressive Addition Lenses Based on Gabor Holography.

PubMed

Perucho, Beatriz; Picazo-Bueno, José Angel; Micó, Vicente

2016-05-01

Progressive addition lenses (PALs) are marked with permanent engraved marks (PEMs) at standardized locations. Permanent engraved marks are very useful through the manufacturing and mounting processes, act as locator marks to re-ink the removable marks, and contain useful information about the PAL. However, PEMs are often faint and weak, obscured by scratches, partially occluded, and difficult to recognize on tinted lenses or with antireflection or scratch-resistant coatings. The aim of this article is to present a new generation of portable marking reader based on an extremely simplified concept for visualization and identification of PEMs in PALs. Permanent engraved marks on different PALs are visualized using classical Gabor holography as underlying principle. Gabor holography allows phase sample visualization with adjustable magnification and can be implemented in either classical or digital versions. Here, visual Gabor holography is used to provide a magnified defocused image of the PEMs onto a translucent visualization screen where the PEM is clearly identified. Different types of PALs (conventional, personalized, old and scratched, sunglasses, etc.) have been tested to visualize PEMs with the proposed marking reader. The PEMs are visible in every case, and variable magnification factor can be achieved simply moving up and down the PAL in the instrument. In addition, a second illumination wavelength is also tested, showing the applicability of this novel marking reader for different illuminations. A new concept of marking reader ophthalmic instrument has been presented and validated in the laboratory. The configuration involves only a commercial-grade laser diode and a visualization screen for PEM identification. The instrument is portable, economic, and easy to use, and it can be used for identifying patient's current PAL model and for marking removable PALs again or finding test points regardless of the age of the PAL, its scratches, tints, or coatings.

Fiber-Coupled, Time-Gated { {Al}}_{2}{ {O}}_{3} : { {C}} Radioluminescence Dosimetry Technique and Algorithm for Radiation Therapy With LINACs

NASA Astrophysics Data System (ADS)

Magne, Sylvain; Deloule, Sybelle; Ostrowsky, Aimé; Ferdinand, Pierre

2013-08-01

An original algorithm for real-time In Vivo Dosimetry (IVD) based on Radioluminescence (RL) of dosimetric-grade Al2O3:C crystals is described and demonstrated in reference conditions with 12-MV photon beams from a Saturne 43 linear accelerator (LINAC), simulating External Beam Radiation Therapy (EBRT) treatments. During the course of irradiation, a portion of electrons is trapped within the Al2O3:C crystal while another portion recombines and generates RL, recorded on-line using an optical fiber. The RL sensitivity is dose-dependent and increases in accordance with the concentration of trapped electrons. Once irradiation is completed, the Al2O3:C crystal is reset by laser light (reusable) and the resultant OSL (Optically Stimulated Luminescence) is also collected back by the remote RL-OSL reader and finally integrated to yield the absorbed dose. During irradiation, scintillation and Cerenkov lights generated within the optical fiber (“stem effect”) are removed by a time-discrimination method involving a discriminating unit and a fiber-coupled BGO scintillator placed in the irradiation room, next to the LINAC. The RL signals were then calibrated with respect to reference dose and dose rate data using an ionization chamber (IC). The algorithm relies upon the integral of the RL and provides the accumulated dose (useful to the medical physicist) at any time during irradiation, the dose rate being derived afterwards. It is tested with both step and arbitrary dose rate profiles, manually operated from the LINAC control desk. The doses measured by RL and OSL are both compared to reference doses and deviations are about ±2% and ±1% respectively, thus demonstrating the reliability of the algorithm for arbitrary profiles and wide range of dose rates. Although the calculation was done off-line, it is amenable to real-time processing during irradiation.

SEMICONDUCTOR PHYSICS Dose-rate dependence of optically stimulated luminescence signal

NASA Astrophysics Data System (ADS)

Pingqiang, Wei; Zhaoyang, Chen; Yanwei, Fan; Yurun, Sun; Yun, Zhao

2010-10-01

Optically stimulated luminescence (OSL) is the luminescence emitted from a semiconductor during its exposure to light. The OSL intensity is a function of the total dose absorbed by the sample. The dose-rate dependence of the OSL signal of the semiconductor CaS doped Ce and Sm was studied by numerical simulation and experiments. Based on a one-trap/one-center model, the whole OSL process was represented by a series of differential equations. The dose-rate properties of the materials were acquired theoretically by solving the equations. Good coherence was achieved between numerical simulation and experiments, both of which showed that the OSL signal was independent of dose rate. This result validates that when using OSL as a dosimetry technique, the dose-rate effect can be neglected.

Studying CaSO4:Eu as an OSL phosphor

NASA Astrophysics Data System (ADS)

Guckan, Veysi; Altunal, Volkan; Nur, Necmettin; Depci, Tolga; Ozdemir, Adnan; Kurt, Kasim; Yu, Yan; Yegingil, Ihami; Yegingil, Zehra

2017-09-01

This study was carried out to investigate the properties of the OSL signal from Eu-doped calcium sulfate (CaSO4:Eu) phosphor and study on its thermal behavior as a function of temperature under a series of luminescence experiments. The suitability of its usage as an optically stimulated luminescence (OSL) dosimeter was also checked. CaSO4:Eu was synthesized using the precipitation method and prepared in pellet form. The dopant concentration value was performed as 0.1 mol%. The synthesized CaSO4:Eu was analyzed by X-ray diffraction (XRD) method to confirm the product. To have an idea about the crystallography and microstructure morphology of the material, scanning electron microscope (SEM) analysis were carried out. It was found that the OSL signal is a resultant signal having three components and exhibits thermal quenching above 150 °C. The excitation spectrum of CaSO4:Eu showed different peaks in the region 220-360 nm with the highest one at 269 nm. Thermoluminescence (TL) signals of CaSO4:Eu pellets were obtained and compared with the TL signals obtained after OSL measurements of the same pellets by blue light stimulation. The low temperature peak near 180 °C did not show any significant change in TL after OSL measurement whereas the high temperature peak at 240 °C was bleached with the blue light illumination and might be responsible for the observed OSL signal. The dosimetric properties such as dose response, minimum detectable dose, energy response, reusability, fading properties, thermal stability and effect of reading temperatures on OSL signals were examined. OSL signals of CaSO4:Eu pellets were decreased by approximately 8% at the end of the 24 h and by about 7% at the end of 28 days when compared with the first readout. The thermal stability of the ∼240 °C TL peak and OSL signal using isothermal decay measurements were used to determine the trap parameters. The CaSO4:Eu OSL dosimeter in accordance with the presented study allows a high-sensitivity OSL phosphor whose host material was previously known as conventional synthetic CaSO4 TLD material.

Enhancing the Usability of an Optical Reader System to Support Point-of-Care Rapid Diagnostic Testing: An Iterative Design Approach.

PubMed

Hohenstein, Jess; O'Dell, Dakota; Murnane, Elizabeth L; Lu, Zhengda; Erickson, David; Gay, Geri

2017-11-21

In today's health care environment, increasing costs and inadequate medical resources have created a worldwide need for more affordable diagnostic tools that are also portable, fast, and easy to use. To address this issue, numerous research and commercial efforts have focused on developing rapid diagnostic technologies; however, the efficacy of existing systems has been hindered by usability problems or high production costs, making them infeasible for deployment in at-home, point-of-care (POC), or resource-limited settings. The aim of this study was to create a low-cost optical reader system that integrates with any smart device and accepts any type of rapid diagnostic test strip to provide fast and accurate data collection, sample analysis, and diagnostic result reporting. An iterative design methodology was employed by a multidisciplinary research team to engineer three versions of a portable diagnostic testing device that were evaluated for usability and overall user receptivity. Repeated design critiques and usability studies identified a number of system requirements and considerations (eg, software compatibility, biomatter contamination, and physical footprint) that we worked to incrementally incorporate into successive system variants. Our final design phase culminated in the development of Tidbit, a reader that is compatible with any Wi-Fi-enabled device and test strip format. The Tidbit includes various features that support intuitive operation, including a straightforward test strip insertion point, external indicator lights, concealed electronic components, and an asymmetric shape, which inherently signals correct device orientation. Usability testing of the Tidbit indicates high usability for potential user communities. This study presents the design process, specification, and user reception of the Tidbit, an inexpensive, easy-to-use, portable optical reader for fast, accurate quantification of rapid diagnostic test results. Usability testing suggests that the reader is usable among and can benefit a wide group of potential users, including in POC contexts. Generally, the methodology of this study demonstrates the importance of testing these types of systems with potential users and exemplifies how iterative design processes can be employed by multidisciplinary research teams to produce compelling technological solutions. ©Jess Hohenstein, Dakota O'Dell, Elizabeth L Murnane, Zhengda Lu, David Erickson, Geri Gay. Originally published in JMIR Human Factors (http://humanfactors.jmir.org), 21.11.2017.

Preparation of waterproof OSL dosimeters from hygroscopic materials with a special reference to NaCl:Cu

NASA Astrophysics Data System (ADS)

More, Y. K.; Wankhede, S. P.; Patil, R. R.; Kulkarni, M. S.; Kumar, Munish; Moharil, S. V.

2016-05-01

Optically stimulated luminescence (OSL) originally developed for geological/archaeological dating, has been found very useful for diverse applications in the field of radiation dosimetry. There is still a scarcity of OSL materials with demonstrated properties suited to dosimetry applications. Progress on the development of OSL materials with engineered properties has been slow and most research has focused on the OSL characterization of existing materials. One of the reasons for availability of only a handful of OSL dosimetry materials with adequate properties is that they have to satisfy certain stringent conditions necessary for such applications. Especially, hygroscopic materials are considered totally unsuitable. The efforts were made in our laboratory to overcome this problem. It is shown here that "water-proof" dosimeters can be prepared from even hygroscopic materials such as NaCl.

Optically stimulated luminescence in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass

NASA Astrophysics Data System (ADS)

Nanto, H.; Nakagawa, R.; Takei, Y.; Hirasawa, K.; Miyamoto, Y.; Masai, H.; Kurobori, T.; Yanagida, T.; Fujimoto, Y.

2015-06-01

An intense optically stimulated luminescence (OSL) was observed, for the first time, in x-ray irradiated xSnO-(25-x)SrO-75B2O3 glass. It was found that the peak wavelength of OSL emission spectrum and its stimulation spectrum is about 400 nm and 600 nm, respectively. The OSL intensity is depended on the SnO contents (x=0.05-1.5) and the most intense OSL was observed in 1.0 mol% SnO doped glass. It was found that the OSL intensity is increased with increasing x-ray absorbed dose. Fairly good fading characteristics were observed in the x-ray irradiated glass, showing that this glass is useful as a candidate for OSL sensor materials for ionizing radiation monitoring.

Entrance surface dose measurements using a small OSL dosimeter with a computed tomography scanner having 320 rows of detectors.

PubMed

Takegami, Kazuki; Hayashi, Hiroaki; Yamada, Kenji; Mihara, Yoshiki; Kimoto, Natsumi; Kanazawa, Yuki; Higashino, Kousaku; Yamashita, Kazuta; Hayashi, Fumio; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

2017-03-01

Entrance surface dose (ESD) measurements are important in X-ray computed tomography (CT) for examination, but in clinical settings it is difficult to measure ESDs because of a lack of suitable dosimeters. We focus on the capability of a small optically stimulated luminescence (OSL) dosimeter. The aim of this study is to propose a practical method for using an OSL dosimeter to measure the ESD when performing a CT examination. The small OSL dosimeter has an outer width of 10 mm; it is assumed that a partial dose may be measured because the slice thickness and helical pitch can be set to various values. To verify our method, we used a CT scanner having 320 rows of detectors and checked the consistencies of the ESDs measured using OSL dosimeters by comparing them with those measured using Gafchromic™ films. The films were calibrated using an ionization chamber on the basis of half-value layer estimation. On the other hand, the OSL dosimeter was appropriately calibrated using a practical calibration curve previously proposed by our group. The ESDs measured using the OSL dosimeters were in good agreement with the reference ESDs from the Gafchromic™ films. Using these data, we also estimated the uncertainty of ESDs measured with small OSL dosimeters. We concluded that a small OSL dosimeter can be considered suitable for measuring the ESD with an uncertainty of 30 % during CT examinations in which pitch factors below 1.000 are applied.

LiMgPO 4:Tb,B - A new sensitive OSL phosphor for dosimetry

NASA Astrophysics Data System (ADS)

Dhabekar, Bhushan; Menon, S. N.; Alagu Raja, E.; Bakshi, A. K.; Singh, A. K.; Chougaonkar, M. P.; Mayya, Y. S.

2011-08-01

Optically Stimulated Luminescence (OSL) technique has emerged as a serious competitor to Thermally Stimulated Luminescence (TSL) technique in various dosimetric applications, especially after the development of crystalline alumina (Al 2O 3:C) doped with carbon. Since then, several attempts are being made to develop other possible materials for OSL based dosimetric applications. Efforts conducted in our laboratory in this direction have led to the development of a new phosphor, Lithium Magnesium Phosphate doped with terbium and boron (LiMgPO 4:Tb,B). This phosphor is prepared by solid-state diffusion method involving conventional air furnaces with operating temperature 1000 °C and easily amenable to large scale production without compromising primary dosimetric advantages. In this work we present some of the dosimetric OSL characteristics of this phosphor. The phosphor exhibits a main TSL peak at 250 °C. The phosphor also emits OSL, when the irradiated phosphor is stimulated with 470 nm light with the OSL sensitivity 1.3 times that of commercially available Al 2O 3:C. Photoluminescence (PL) emission spectrum consists of sharp lines characteristics of Tb 3+ emission. The OSL discs made out of this phosphor are reusable up to at least 50 cycles, the phosphor exhibits dose linearity up to 1 kGy. Minimum detectable dose is found to be 20 μGy and fading of the OSL signal is found to be about 16% in four days, after which the OSL signal stabilizes.

Gamma response characterizations of optically stimulated luminescence (OSL) affects personal dosimetry

NASA Astrophysics Data System (ADS)

Monthonwattana, S.; Esor, J.; Rungseesumran, T.; Intang, A.

2017-06-01

Optically Stimulated Luminescence (OSL) is the current technique of personal dosimetry changed by Nuclear Technology Service Center instead of Thermoluminescence dosimetry (TLD) because OSL has more advantages, such as repeat reading and elimination of heating process. In this study, OSL was used to test the gamma response characterizations. Detailed OSL investigation on personal dosimetry was carried out in the dose range of 0.2 - 3.0 mSv. The batch homogeneity was 7.66%. R2 value of the linear regression was 0.9997. The difference ratio of angular dependence at ± 60° was 8.7%. Fading of the reading was about 3%.

Tl And Osl Response Of Turquoise For Dosimetric Application

NASA Astrophysics Data System (ADS)

Subedi, B.; Afouxenidis, D.; Polymeris, G. S.; Tsirlignanis, N.; Paraskevopoulos, K. M.; Kitis, G.

Turquoise is one of the amongst first gem stones used in jewelry and possessing cultural value since 2000 BC (at least). This work attempts characterize this stone scientifically using both thermally (TL) and optically stimulated luminescence (OSL) techniques. The experimental investigation included 1) the study of the natural TL and OSL signals, 2) the reproducibility of TL sensitivity over repeated irradiation and TL readout cycles, 3) dependence of sensitivity on annealing temperatures and 4) the TL and OSL dose response curves. The potential use of the TL and OSL techniques in determination of provenance, accidental dosimetry and probably to authenticity and dating purposes are then discussed.

Hormones and growth factors in the pathogenesis of spinal ligament ossification

PubMed Central

Li, Hai; Jiang, Lei-Sheng

2007-01-01

Ossification of the spinal ligaments (OSL) is a pathologic condition that causes ectopic bone formation and subsequently results in various degrees of neurological deficit, but the etiology of OSL remains almost unknown. Some systemic hormones, such as 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin and leptin, and local growth factors, such as transforming growth factor-β (TGF-β), and bone morphogenetic protein (BMP), have been studied and are thought to be involved in the initiation and development of OSL. This review article summarizes these studies, delineates the possible mechanisms, and puts forward doubts and new questions. The related findings from studies of genes and target cells in the ligament of OSL are also discussed. Although these findings may be helpful in understanding the pathogenesis of OSL, much more research needs to be conducted in order to investigate the nature of OSL. PMID:17426989

Hormones and growth factors in the pathogenesis of spinal ligament ossification.

PubMed

Li, Hai; Jiang, Lei-Sheng; Dai, Li-Yang

2007-08-01

Ossification of the spinal ligaments (OSL) is a pathologic condition that causes ectopic bone formation and subsequently results in various degrees of neurological deficit, but the etiology of OSL remains almost unknown. Some systemic hormones, such as 1,25-dihydroxyvitamin D, parathyroid hormone (PTH), insulin and leptin, and local growth factors, such as transforming growth factor-beta (TGF-beta), and bone morphogenetic protein (BMP), have been studied and are thought to be involved in the initiation and development of OSL. This review article summarizes these studies, delineates the possible mechanisms, and puts forward doubts and new questions. The related findings from studies of genes and target cells in the ligament of OSL are also discussed. Although these findings may be helpful in understanding the pathogenesis of OSL, much more research needs to be conducted in order to investigate the nature of OSL.

Preparation of waterproof OSL dosimeters from hygroscopic materials with a special reference to NaCl:Cu

DOE Office of Scientific and Technical Information (OSTI.GOV)

More, Y. K., E-mail: moreyogesh153@gmail.com; Moharil, S. V.; Wankhede, S. P.

Optically stimulated luminescence (OSL) originally developed for geological/archaeological dating, has been found very useful for diverse applications in the field of radiation dosimetry. There is still a scarcity of OSL materials with demonstrated properties suited to dosimetry applications. Progress on the development of OSL materials with engineered properties has been slow and most research has focused on the OSL characterization of existing materials. One of the reasons for availability of only a handful of OSL dosimetry materials with adequate properties is that they have to satisfy certain stringent conditions necessary for such applications. Especially, hygroscopic materials are considered totally unsuitable.more » The efforts were made in our laboratory to overcome this problem. It is shown here that “water-proof” dosimeters can be prepared from even hygroscopic materials such as NaCl.« less

Basic Internet Software Toolkit.

ERIC Educational Resources Information Center

Buchanan, Larry

1998-01-01

Once schools are connected to the Internet, the next step is getting network workstations configured for Internet access. This article describes a basic toolkit comprising software currently available on the Internet for free or modest cost. Lists URLs for Web browser, Telnet, FTP, file decompression, portable document format (PDF) reader,…

OSL properties of KMgF3:Tm3+ for dosimetric applications as OSL dosimeter.

PubMed

Camargo, Luis; Cruz, Lituania Pérez; Cruz-Zaragoza, Epifanio; Ovalle, Segundo Martínez; Marcazzó, Julián

2018-04-06

The optically stimulated luminescence (OSL) properties of undoped and Tm 3+ -doped KMgF 3 fluoroperovskite have been investigated for the first time. KMgF 3 compounds were synthesized by solid state reaction method and two different procedures were employed to improve the contact among the reagents, namely, the compressed powder was put either in an alumina crucible or in a platinum foil. The maximum OSL emission was found in samples prepared in an alumina crucible and doped with 0.5% mol of thulium. The radioluminescence (RL) spectrum shows two emission peaks at 455 and 360 nm, which can be ascribed to the 1 D 2 - 3 F 4 and 1 D 2 - 3 H 6 transitions of Tm 3+ cations. The OSL dosimetric properties of the most promising composition, namely, KMgF 3 :Tm 3+ (0.5% mol), have also been determined and analyzed. This compound exhibits good linearity in the dose range from 0.1 up to 100 Gy and satisfactory repeatability with a percentage standard deviation of 2.4%. Therefore, an OSL fading of approximately 75% in the first 36 h of storage is observed and then, the response remains almost constant. These characteristics, together with a minimum detectable dose of 0.04 Gy and the rapid erasing of the OSL signal after 100 s of stimulation, which makes feasible to bleach completely the residual OSL in order to restore the sample between dose measurements, suggest the potential of this perovskite as OSL dosimeter. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optically Stimulated Luminescence Analysis Method for High Dose Rate Using an Optical Fiber Type Dosimeter

NASA Astrophysics Data System (ADS)

Ueno, Katsunori; Tominaga, Kazuo; Tadokoro, Takahiro; Ishizawa, Koji; Takahashi, Yoshinori; Kuwabara, Hitoshi

2016-08-01

The investigation of air dose rates at locations in the Fukushima Dai-ichi Nuclear Power Station is necessary for safe removal of the molten nuclear fuel. The target performance for the investigation is to analyze a dose rate in the range of 10-3 Gy/h to 102 Gy/h with a measurement precision of ±4.0% full scale (F.S.) at a measurement interval of 60 s. In order to achieve this target, the authors proposed an optically stimulated luminescence (OSL) analysis method using prompt OSL for a wide dynamic range of dose rates; the OSL is generated using BaFBr:Eu with a fast decay time constant. The luminescence intensity by prompt OSL was formulated by the electron concentration of the trapping state during gamma ray and stimulation light irradiations. The prototype OSL monitor using BaFBr:Eu was manufactured for investigation of prompt OSL and evaluation of the measurement precision. The time dependence of the luminescence intensity by prompt OSL was analyzed by irradiating the OSL sensor in a 60Co irradiation facility. The measured dose rates were obtained in a prompt mode and an accumulating mode with a precision of ±3.3% F.S. for the dose rate range of 9.5 ×10-4 Gy/h to 1.2 ×102 Gy/h.

Evaluation of a real-time BeO ceramic fiber-coupled luminescence dosimetry system for dose verification of high dose rate brachytherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Santos, Alexandre M. Caraça, E-mail: alexandre.santos@adelaide.edu.au; Mohammadi, Mohammad; Shahraam, Afshar V.

Purpose: The authors evaluate the capability of a beryllium oxide (BeO) ceramic fiber-coupled luminescence dosimeter, named radioluminescence/optically stimulated luminescence (RL/OSL) BeO FOD, for dosimetric verification of high dose rate (HDR) treatments. The RL/OSL BeO FOD is capable of RL and OSL measurements. Methods: The RL/OSL BeO FOD is able to be inserted in 6F proguide needles, used in interstitial HDR treatments. Using a custom built Perspex phantom, 6F proguide needles could be submerged in a water tank at 1 cm separations from each other. A second background fiber was required to correct for the stem effect. The stem effect, dosemore » linearity, reproducibility, depth-dose curves, and angular and temperature dependency of the RL/OSL BeO FOD were characterised using an Ir-192 source. The RL/OSL BeO FOD was also applied to the commissioning of a 10 mm horizontal Leipzig applicator. Results: Both the RL and OSL were found to be reproducible and their percentage depth-dose curves to be in good agreement with those predicted via TG-43. A combined uncertainty of 7.9% and 10.1% (k = 1) was estimated for the RL and OSL, respectively. For the 10 mm horizontal Leipzig applicator, measured percentage depth doses were within 5% agreement of the published reference calculations. The output at the 3 mm prescription depth for a 1 Gy delivery was verified to be 0.99 ± 0.08 Gy and 1.01 ± 0.10 Gy by the RL and OSL, respectively. Conclusions: The use of the second background fiber under the current setup means that the two fibers cannot fit into a single 6F needle. Hence, use of the RL is currently not adequate for the purpose of in vivo brachytherapy dosimetry. While not real-time, the OSL is shown to be adequate for in vivo brachytherapy dosimetry.« less

Evaluation of a real-time BeO ceramic fiber-coupled luminescence dosimetry system for dose verification of high dose rate brachytherapy.

PubMed

Santos, Alexandre M Caraça; Mohammadi, Mohammad; Afshar V, Shahraam

2015-11-01

The authors evaluate the capability of a beryllium oxide (BeO) ceramic fiber-coupled luminescence dosimeter, named radioluminescence/optically stimulated luminescence (RL/OSL) BeO FOD, for dosimetric verification of high dose rate (HDR) treatments. The RL/OSL BeO FOD is capable of RL and OSL measurements. The RL/OSL BeO FOD is able to be inserted in 6F proguide needles, used in interstitial HDR treatments. Using a custom built Perspex phantom, 6F proguide needles could be submerged in a water tank at 1 cm separations from each other. A second background fiber was required to correct for the stem effect. The stem effect, dose linearity, reproducibility, depth-dose curves, and angular and temperature dependency of the RL/OSL BeO FOD were characterised using an Ir-192 source. The RL/OSL BeO FOD was also applied to the commissioning of a 10 mm horizontal Leipzig applicator. Both the RL and OSL were found to be reproducible and their percentage depth-dose curves to be in good agreement with those predicted via TG-43. A combined uncertainty of 7.9% and 10.1% (k=1) was estimated for the RL and OSL, respectively. For the 10 mm horizontal Leipzig applicator, measured percentage depth doses were within 5% agreement of the published reference calculations. The output at the 3 mm prescription depth for a 1 Gy delivery was verified to be 0.99±0.08 Gy and 1.01±0.10 Gy by the RL and OSL, respectively. The use of the second background fiber under the current setup means that the two fibers cannot fit into a single 6F needle. Hence, use of the RL is currently not adequate for the purpose of in vivo brachytherapy dosimetry. While not real-time, the OSL is shown to be adequate for in vivo brachytherapy dosimetry.

Are Ebooks Any Good?

ERIC Educational Resources Information Center

Guernsey, Lisa

2011-01-01

Until recently, ebooks for young children haven't been part of the hyped vernacular of "game-changing" technology. Instead, ebook conversations have focused on textbooks for older students or text-heavy, adult-oriented titles downloaded to ereaders like the Kindle, Nook, and Sony e-Reader. The arrival of portable, full-color, touchscreen devices…

Optically stimulated luminescence in doped NaCl

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gaikwad, S. U., E-mail: gaikwadsonali09@yahoo.com; Patil, R. R.; Kulkarni, M. S.

NaCl:Ca,Cu,P NaCl:Mg,Cu,P OSL phosphors are synthesized. Intense OSL is observed in these samples which is 14 times more than Al{sub 2}O{sub 3}:C. Same samples coated with PVA (poly vinyl actetae) polymer also show similar OSL properties and these coated samples are found to be less susceptible to the moisture due to protected layer of hydrophobic polymer. These coated samples may be useful as OSL dosimetersdue to high sensitivity and less or no susceptibility to moisture.

Influence of shallow traps on time-resolved optically stimulated luminescence measurements of Al2O3:C,Mg

NASA Astrophysics Data System (ADS)

Denis, G.; Akselrod, M. S.; Yukihara, E. G.

2011-05-01

The objective of this paper is to investigate the influence of shallow traps on the signals from Al2O3:C,Mg obtained using time-resolved optically stimulated luminescence (TR-OSL) measurements through experiments and numerical simulations. TR-OSL measurements of Al2O3:C,Mg were carried out and the resulting optically stimulated luminescence (OSL) curves were investigated as a function of the temperature. The numerical simulations were carried out using the rate-equations for a simplified model of Al2O3:C,Mg containing two types of luminescence centers with different luminescence lifetimes and three types of electron traps (a shallow trap, a main dosimetric trap, and a thermally disconnected deep trap). Both experimental results and simulations show that the OSL signals during and between the stimulation pulses are affected by the presence of shallow traps. However, with an appropriate choice of timing parameters, the influence of shallow traps can be reduced by calculating the difference between the signals during and between stimulation pulses. Therefore, TR-OSL can be useful in dosimetry using materials having a large concentration of shallow traps and OSL components with short luminescence lifetimes, for example Al2O3:C,Mg and BeO. Our results also show that the presence of shallow traps has to be taken into account when using the TR-OSL for discrimination between luminescence centers with different luminescence lifetimes, or separation between the OSL from different materials based on their characteristic luminescence lifetimes. The experimental results also show evidence of thermal assistance in the OSL process of Al2O3:C,Mg.

OSL studies of local bricks for retrospective dosimetric application

NASA Astrophysics Data System (ADS)

Singh, A. K.; Menon, S. N.; Kadam, S. Y.; Koul, D. K.; Datta, D.

2016-09-01

Luminescence properties of quartz extracted from bricks has been reported worldwide for its use in dose estimation in case of nuclear or radiological accident. Accordingly, in this study the feasibility of utilizing the optically stimulated luminescence (OSL) emission of quartz extracted from red bricks collected from three different locations in and around Mumbai, India for retrospective dosimetry was explored. Thermoluminescence and OSL characterization of the samples were carried out. The growth curve, thermal stability and equivalent dose plateau of the OSL signal suggested the signals to be well behaving. Subsequently, the dose recovery tests carried for different administered doses, using single aliquot regenerative protocol, demonstrated the feasibility of the OSL emissions of these samples for dose evaluation in retrospective dosimetry.

OSL studies of alkali fluoroperovskite single crystals for radiation dosimetry

NASA Astrophysics Data System (ADS)

Daniel, D. Joseph; Raja, A.; Madhusoodanan, U.; Annalakshmi, O.; Ramasamy, P.

2016-08-01

This paper presents a preliminary investigation of the optically stimulated luminescence (OSL) of alkali fluoroperovskite single crystals for radiation dosimetry. The perovskite-like KMgF3, NaMgF3 and LiBaF3 polycrystalline compounds doped with rare earths (Eu2+ and Ce3+) were synthesized by standard solid state reaction technique. Phase purity of the synthesized compounds was analyzed by powder X-ray diffraction technique. Single crystals of these compounds have been grown from melt by using vertical Bridgman-Stockbarger method. The Linearly Modulated OSL and Continuous Wave OSL measurements were performed in these alkali fluorides using blue light stimulation. Thermal bleaching experiments have shown that OSL signals originate from traps which are unstable near 200 °C, thus proving the suitability of the signals for dosimetric purposes. Optical bleaching measurements were also performed for these fluoride samples. OSL dose response was studied as a function of dose which was found to increase with beta dose.

The use of stimulated electron emission (SEE) in homeland security applications

NASA Astrophysics Data System (ADS)

Ing, H.; Andrews, H. R.; Facina, M.; Lee, W. T.; Niu, H. W.

2012-06-01

Certain insulating solids can store a fraction of the absorbed energy when irradiated by ionizing radiation. The stored energy can be released subsequently by heating or optical stimulation. As a result, light may be emitted through Thermoluminescence (TL) or Optically-Stimulated Luminescence (OSL) and electrons may be emitted through Thermally-Stimulated Electron Emission (TSEE) or Optically-Stimulated Electron Emission (OSEE). TL and OSL are widely used in current radiation dosimetry systems. However, despite considerable research effort during the early 1970s, SEE was not commonly adopted for dosimetry applications. One of the main reasons is that SEE is a surface phenomenon, while luminescence is a bulk phenomenon, making SEE more susceptible to humidity, absorption of gases, minor physical defects and handling, both before and after irradiation. Nevertheless, it has been recognized that SEE may be useful for homeland security applications in nuclear forensics, where dose accuracy is not the primary performance metric. In this research, we are investigating the use of SEE for nuclear forensic applications. Many common materials, both natural and man-made, exhibit the phenomenon, providing an opportunity to use the environment itself as an in-situ radiation detector. We have designed and constructed a unique prototype reader for conducting SEE measurements. We have demonstrated that the SEE measurements from a variety of materials are quantitatively reproducible and correlated to radiation exposure. Due to the broad applicability of SEE, significant additional studies are warranted to optimize this novel technique for nuclear forensic and other applications.

An IoT Reader for Wireless Passive Electromagnetic Sensors.

PubMed

Galindo-Romera, Gabriel; Carnerero-Cano, Javier; Martínez-Martínez, José Juan; Herraiz-Martínez, Francisco Javier

2017-03-28

In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of the sensing system. In this work, a novel low-cost and portable Internet-of-Things (IoT) reader for passive wireless electromagnetic sensors is proposed. The reader is used to interrogate the sensors within a short-range wireless link avoiding the direct contact with the substances under test. The IoT functionalities of the reader allows remote sensing from computers and handheld devices. For that purpose, the proposed design is based on four functional layers: the radiating layer, the RF interface, the IoT mini-computer and the power unit. In this paper a demonstrator of the proposed reader is designed and manufactured. The demonstrator shows, through the remote measurement of different substances, that the proposed system can estimate the dielectric permittivity. It has been demonstrated that a linear approximation with a small error can be extracted from the reader measurements. It is remarkable that the proposed reader can be used with other type of electromagnetic sensors, which transduce the magnitude variations in the frequency domain.

An IoT Reader for Wireless Passive Electromagnetic Sensors

PubMed Central

Galindo-Romera, Gabriel; Carnerero-Cano, Javier; Martínez-Martínez, José Juan; Herraiz-Martínez, Francisco Javier

2017-01-01

In the last years, many passive electromagnetic sensors have been reported. Some of these sensors are used for measuring harmful substances. Moreover, the response of these sensors is usually obtained with laboratory equipment. This approach highly increases the total cost and complexity of the sensing system. In this work, a novel low-cost and portable Internet-of-Things (IoT) reader for passive wireless electromagnetic sensors is proposed. The reader is used to interrogate the sensors within a short-range wireless link avoiding the direct contact with the substances under test. The IoT functionalities of the reader allows remote sensing from computers and handheld devices. For that purpose, the proposed design is based on four functional layers: the radiating layer, the RF interface, the IoT mini-computer and the power unit. In this paper a demonstrator of the proposed reader is designed and manufactured. The demonstrator shows, through the remote measurement of different substances, that the proposed system can estimate the dielectric permittivity. It has been demonstrated that a linear approximation with a small error can be extracted from the reader measurements. It is remarkable that the proposed reader can be used with other type of electromagnetic sensors, which transduce the magnitude variations in the frequency domain. PMID:28350356

OSL response bleaching of BeO samples, using fluorescent light and blue LEDs

NASA Astrophysics Data System (ADS)

Groppo, D. P.; Caldas, L. V. E.

2016-07-01

The optically stimulated luminescence (OSL) is widely used as a dosimetric technique for many applications. In this work, the OSL response bleaching of BeO samples was studied. The samples were irradiated using a beta radiation source (90Sr+90Y); the bleaching treatments (fluorescent light and blue LEDs) were performed, and the results were compared. Various optical treatment time intervals were tested until reaching the complete bleaching of the OSL response. The best combination of the time interval and bleaching type was analyzed.

[Fabrication of annealing equipment for optically stimulated luminescence (OSL) dosimeter].

PubMed

Nakagawa, Kohei; Hayashi, Hiroaki; Okino, Hiroki; Takegami, Kazuki; Okazaki, Tohru; Kobayashi, Ikuo

2014-10-01

The optically stimulated luminescence (OSL) dosimeter is a useful detector for measuring absorbed doses of X-rays. A small-type OSL dosimeter, "nanoDot", has recently been developed by Landauer, Inc., who also manufacture "microStar" reading equipment. However, additional annealing equipment is needed if the nanoDot OSL dosimeter is used repeatedly. The aim of this study was to fabricate suitable annealing equipment using commonly available products. Our device positions four fluorescent light tubes in a close configuration. The heat from the fluorescent light tubes is dissipated using fans. Experiments using diagnostic X-ray equipment were carried out to evaluate the capability of our annealing equipment. The results indicated that our equipment can fully anneal the nanoDot OSL dosimeter with annealing times of approximately 20 hours.

An optically stimulated luminescence system to measure dose profiles in x-ray computed tomography

NASA Astrophysics Data System (ADS)

Yukihara, E. G.; Ruan, C.; Gasparian, P. B. R.; Clouse, W. J.; Kalavagunta, C.; Ahmad, S.

2009-10-01

This paper describes an LED-based optically stimulated luminescence (OSL) system for dose profile measurements using OSL detector strips and investigates its performance in x-ray computed tomography (CT) dosimetry. To compensate for the energy response of the Al2O3:C OSL detectors, which have an effective atomic number of 11.28, field-specific energy correction factors were determined using two methods: (a) comparing the OSL profiles with ionization chamber point measurements (0.3 cm3 ionization chamber) and (b) comparing the OSL profiles integrated over a 100 mm length with 100 mm long pencil ionization chamber measurements. These correction factors were obtained for the CT body and head phantoms, central and peripheral positions and three x-ray tube potential differences (100 kVp, 120 kVp and 140 kVp). The OSL dose profiles corrected by the energy dependence agreed with the ionization chamber point measurements over the entire length of the phantom (300 mm). For 120 kVp x-ray tube potential difference, the CTDI100 values calculated using the OSL dose profiles corrected for the energy dependence and those obtained from an independent measurement with a 100 mm long pencil ionization chamber also agreed within ±5%.

Fundamentals of materials, techniques and instrumentation for OSL and FNTD dosimetry

NASA Astrophysics Data System (ADS)

Akselrod, M. S.

2013-02-01

The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al2O3:C as a material of choice for many dosimetric applications including fiberoptic OSL/RL sensors with diameters as small as 300 μm. A new RL/OSL fiberoptic system has a high potential for in vivo and in vitro dosimetry in both radiation therapy and diagnostic mammography. Different aspects of instrumentation, data processing algorithms, post-irradiation and real-time measurements are described. The next technological breakthrough was done with Fluorescent Nuclear Track detectors (FNTD) that has some important advantages in measuring fast neutron and high energy heavy charge particles that became the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology were engineered and successfully demonstrated for occupational and accident dosimetry, for medical dosimetry and radiobiological research.

76 FR 27309 - Committee on Measures of Student Success

Federal Register 2010, 2011, 2012, 2013, 2014

2011-05-11

... version of this document is the document published in the Federal Register. Free Internet access to the... text or Adobe Portable Document Format (PDF) on the Internet at the following site: http://www.ed.gov/news/fed-register/index.html . To use PDF you must have Adobe Acrobat Reader, which is available free...

77 FR 37893 - Privacy Act of 1974; System of Records

Federal Register 2010, 2011, 2012, 2013, 2014

2012-06-25

... official versions of these documents are the documents published in the Federal Register. Free Internet... telephone (TTY), call the Federal Relay Service (FRS), toll free, at 1- 800-877-8339. Individuals with... Portable Document Format (PDF). To use PDF you must have Adobe Acrobat Reader, which is available free at...

MONITORING CULVERT PASSAGE OF JUVENILE SALMONIDS WITH PIT TAGS AND STATIONARY AND PORTABLE PIT-TAG READERS

EPA Science Inventory

Federal land management agencies in the PNW face increasing pressure to replace culverts that do not pass all life history stages of anadromous salmon and trout. Prioritization of culverts for replacement is often based on the physical parameters of culverts, and not on how fish...

Commentary on A Successful Microfiche Program

ERIC Educational Resources Information Center

Campbell, Bill W.

1978-01-01

A chart is given showing external document requests filled by hard copy versus microfiche from January 1976 to January 1977. The main factor contributing to the success of the microfiche program of this aircraft company's library has been getting portable readers into the hands of those engineers most open to the use of film. (Author/JPF)

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications.

PubMed

Pradhan, A S; Lee, J I; Kim, J L

2008-07-01

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al(2)O(3):C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al(2)O(3):C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF(3):Eu(2+) appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al(2)O(3):C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose measurements in clinical applications. A brief review of the recent developments is presented.

Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications

PubMed Central

Pradhan, A. S.; Lee, J. I.; Kim, J. L.

2008-01-01

During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al2O3:C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al2O3:C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF3:Eu2+ appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al2O3:C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose measurements in clinical applications. A brief review of the recent developments is presented. PMID:19893698

Technical Note: Precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vrieze, Thomas J.; Sturchio, Glenn M.; McCollough, Cynthia H.

Purpose: To determine the precision and accuracy of CTDI{sub 100} measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. Methods: One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements weremore » made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI{sub 100}. Results: The mean precision averaged over 28 datasets containing five measurements each was 1.4%{+-} 0.6%, range = 0.6%-2.7% for OSL and 0.08%{+-} 0.06%, range = 0.02%-0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI{sub 100} values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI{sub 100} relative to the ion chamber 21/28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Conclusions: Measurements of CTDI{sub 100} with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI{sub 100} values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile.« less

Technical Note: Precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index

PubMed Central

Vrieze, Thomas J.; Sturchio, Glenn M.; McCollough, Cynthia H.

2012-01-01

Purpose: To determine the precision and accuracy of CTDI100 measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. Methods: One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements were made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI100. Results: The mean precision averaged over 28 datasets containing five measurements each was 1.4% ± 0.6%, range = 0.6%–2.7% for OSL and 0.08% ± 0.06%, range = 0.02%–0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI100 values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI100 relative to the ion chamber 21/28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Conclusions: Measurements of CTDI100 with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI100 values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile. PMID:23127052

Technical note: precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index.

PubMed

Vrieze, Thomas J; Sturchio, Glenn M; McCollough, Cynthia H

2012-11-01

To determine the precision and accuracy of CTDI(100) measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements were made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI(100). The mean precision averaged over 28 datasets containing five measurements each was 1.4% ± 0.6%, range = 0.6%-2.7% for OSL and 0.08% ± 0.06%, range = 0.02%-0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI(100) values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI(100) relative to the ion chamber 21∕28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Measurements of CTDI(100) with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI(100) values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile.

WE-D-17A-06: Optically Stimulated Luminescence Detectors as ‘LET-Meters’ in Proton Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Granville, D; Sahoo, N; Sawakuchi, GO

Purpose: To demonstrate and evaluate the potential of optically stimulated luminescence (OSL) detectors (OSLDs) for measurements of linear energy transfer (LET) in therapeutic proton beams. Methods: Batches of Al2O2:C OSLDs were irradiated with an absorbed dose of 0.2 Gy in un-modulated proton beams of varying LET (0.67 keV/μm to 2.58 keV/μm). The OSLDs were read using continuous wave (CW-OSL) and pulsed (P-OSL) stimulation modes. We parameterized and calibrated three characteristics of the OSL signals as functions of LET: CW-OSL curve shape, P-OSL curve shape and the ratio of the two OSL emission band intensities (ultraviolet/blue ratio). Calibration curves were createdmore » for each of these characteristics to describe their behaviors as functions of LET. The true LET values were determined using a validated Monte Carlo model of the proton therapy nozzle used to irradiate the OSLDs. We then irradiated batches of OSLDs with an absorbed dose of 0.2 Gy at various depths in two modulated proton beams (140 MeV, 4 cm wide spread-out Bragg peak (SOBP) and 250 MeV, 10 cm wide SOBP). The LET values were calculated using the OSL response and the calibration curves. Finally, measured LET values were compared to the true values determined using Monte Carlo simulations. Results: The CW-OSL curve shape, P-OSL curve shape and the ultraviolet/blue-ratio provided proton LET estimates within 12.4%, 5.7% and 30.9% of the true values, respectively. Conclusion: We have demonstrated that LET can be measured within 5.7% using Al2O3:C OSLDs in the therapeutic proton beams used in this investigation. From a single OSLD readout, it is possible to measure both the absorbed dose and LET. This has potential future applications in proton therapy quality assurance, particularly for treatment plans based on optimization of LET distributions. This research was partially supported by the Natural Sciences and Engineering Research Council of Canada.« less

A portable eBook reader for the blind.

PubMed

Velazquez, Ramiro; Hernandez, Hermes; Preza, Enrique

2010-01-01

This paper presents the design and first prototype of the TactoBook system, a novel concept of reading assistive device that aims to make eBooks accessible to the blind. The TactoBook consists of a computer-based software translator that converts fast and automatically any eBook into Braille. The Braille version of the eBook is then encrypted as a file and stored in a USB memory drive which is later inserted and reproduced in a compact, lightweight, and highly-portable tactile terminal. Braille readers can store multiple eBooks in the same USB and access/reproduce them in the tactile terminal without this being plugged to a computer. The first Braille terminal developed is a 10-cell prototype based on a piezoelectric ultrasonic actuation approach. Its overall performance is quite similar to the one obtained with traditional Braille terminals. However, unlike them, the full device is only 1 kg mass and its compact dimensions (20 × 15 × 10 cm) make it easily carried by the user. A technical overview of all subsystems is presented and discussed.

TL and OSL studies of carbon doped magnesium aluminate (MgAl2O4:C)

NASA Astrophysics Data System (ADS)

Raj, Sanu S.; Mishra, D. R.; Soni, Anuj; Grover, V.; Polymeris, G. S.; Muthe, K. P.; Jha, S. K.; Tyagi, A. K.

2016-10-01

The MgAl2O4:C has been synthesized by using two different methods by electron gun and vacuum assisted melting of MgAl2O4 in presence of graphite. The MgAl2O4:C phosphor thus developed by these two different methods have similar types of the TL/OSL defects with multiple overlapping TL glow peaks from 100 °C to 400 °C. The Computerized Curve De-convolution Analysis (CCDA) has been used to measure TL parameters such as thermal trap depth, frequency factor and order of kinetic associated with charge transfer process in TL phenomenon. The investigated TL/OSL results show that these two methods of incorporating carbon in MgAl2O4 have generated closely resemble the defects of similar types in MgAl2O4:C lattice. However, the MgAl2O4:C synthesized by electron gun shows relatively larger concentration of the TL/OSL defects as compared to MgAl2O4:C synthesized using vacuum assisted melting method. The photo-ionization cross-section (PIC) associated with fastest OSL component of MgAl2O4: C is found to be ∼ 0.5 times than that of fastest OSL component of commercially available dosimetric grade α-Al2O3:C. The MgAl2O4:C thus developed shows good dynamic OSL dose linearity from few mGy to 1 Gy. This work reveals that MgAl2O4:C could be developed as potential tissue equivalent OSL / TL material.

Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams.

PubMed

Magne, S; Auger, L; Bordy, J M; de Carlan, L; Isambert, A; Bridier, A; Ferdinand, P; Barthe, J

2008-01-01

This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve.

Fundamentals of Materials, Techniques, and Instrumentation for OSL and FNTD Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akselrod, M. S.

The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al{sub 2}O{sub 3}:C as a material of choice for many dosimetric applications. Different aspects of OSL theory, materials optical and dosimetric properties,more » instrumentation, and data processing algorithms are described. The next technological breakthrough was done with Fluorescent Nuclear Track Detectors (FNTD) that have some important advantages in measuring fast neutron and high energy heavy charge particles that have become the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research.« less

Fundamentals of Materials, Techniques, and Instrumentation for OSL and FNTD Dosimetry

NASA Astrophysics Data System (ADS)

Akselrod, M. S.

2011-05-01

The optically stimulated luminescence (OSL) technique has already become a successful commercial tool in personal radiation dosimetry, medical dosimetry, diagnostic imaging, geological and archeological dating. This review briefly describes the history and fundamental principles of OSL materials, methods and instrumentation. The advantages of OSL technology and instrumentation in comparison with thermoluminescent technique are analyzed. Progress in material and detector engineering has allowed new and promising developments regarding OSL applications in the medical field. Special attention is dedicated to Al2O3:C as a material of choice for many dosimetric applications. Different aspects of OSL theory, materials optical and dosimetric properties, instrumentation, and data processing algorithms are described. The next technological breakthrough was done with Fluorescent Nuclear Track Detectors (FNTD) that have some important advantages in measuring fast neutron and high energy heavy charge particles that have become the latest tool in radiation therapy. New Mg-doped aluminum oxide crystals and novel type of imaging instrumentation for FNTD technology are discussed with regard to application in mixed neutron-gamma fields, medical dosimetry and radiobiological research.

Study of optically stimulated luminescence in LiSrAlF6:Eu2+

NASA Astrophysics Data System (ADS)

More, Y. K.; Nikam, M. S.; Wankhede, S. P.; Moharil, S. V.

2018-05-01

In this context the results on beta induced thermoluminescence and optically stimulated luminescence properties of LiSrAlF6:Eu2+ are reported. Phosphor shows good luminescence properties for both thermal and optical stimulation. The continuous wave optically stimulated luminescence (CW-OSL) signal as recorded using blue (470 nm) stimulation was found to be 37 % that of standard phosphor Lithium Magnesium Phosphate. The phosphor shows linear response of CW-OSL for various exposures ranging from 20 mGy to 10 Gy with minimum detectable dose approximately equal to 13 µGy. About 20% reduction in the TL signal of the phosphor after OSL readout was observed. About 50% fading of OSL signal was observed within three days of irradiation out of which about 35% OSL signal depleted within a day after irradiation.

The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles

NASA Technical Reports Server (NTRS)

Gaza, R.; Yukihara, E. G.; McKeever, S. W. S.

2004-01-01

The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelerator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel(TM) dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4He (150 MeV/u), 12C (400 MeV/u), 28Si (490 MeV/us) and 56Fe (500 MeV/u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV/micrometers in water and doses from 1 to 100 mGy (to water). A 90Sr/90Y beta source, calibrated against a 60Co secondary standard, was used for calibration purposes. For OSL, we used both continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. c2004 Elsevier Ltd. All rights reserved.

The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles.

PubMed

Gaza, R; Yukihara, E G; McKeever, S W S

2004-01-01

The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelerator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel(TM) dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4He (150 MeV/u), 12C (400 MeV/u), 28Si (490 MeV/us) and 56Fe (500 MeV/u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV/micrometers in water and doses from 1 to 100 mGy (to water). A 90Sr/90Y beta source, calibrated against a 60Co secondary standard, was used for calibration purposes. For OSL, we used both continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. c2004 Elsevier Ltd. All rights reserved.

OSL dating of fine-grained quartz from Holocene Yangtze delta sediments

NASA Astrophysics Data System (ADS)

Sugisaki, S.; Buylaert, J. P.; Murray, A. S.; Tada, R.; Zheng, H.; Ke, W.; Saito, K.; Irino, T.; Chao, L.; Shiyi, L.; Uchida, M.

2014-12-01

Flood events in the Yangtze River are associated with variation in East Asian Summer Monsoon (EASM) precipitation. Understanding the frequency and scale of the EASM precipitation during the Holocene is a key to understanding the mechanism and cyclicity of floods and droughts. Because about 70% of the annual discharge occurs during the flood season, the Yangtze delta sediments provide a good archive of EASM precipitation. In this study, we investigate the possibility of applying OSL dating to establishing high-resolution chronologies for the Yangtze delta sediment cores YD13-1H and G3. The objectives of this study are: (1) test whether fine grained quartz in present day suspended particle matter (SPM) is fully bleached or reset before deposition, (2) where possible, test quartz fine- and coarse-grain OSL dating against radiocarbon shell ages, (3) interpret the sediment transport processes through the differential bleaching of quartz and feldspar OSL signals. We show that the SPM collected from the surface water column of the Yangtze River during the flood season is well-bleached (offset ~60 years). Fine-grained pro-delta sediments are thus potentially a good dosimeter for OSL dating. OSL ages sediment cores indicate a pronounced change in sedimentation rate at ~6 ka and ~2ka. These events are consistent with what is known of the evolution of the Yangtze catchment and delta. The delta began to build at ~6 ka (Zhao et al., 1979), and human activities increased significantly in the catchment at ~2ka　(Chen et al., 1985). It is however surprising that the entire top 9 m of sediment only records these two events. The question of whether significant deposition was limited to 2 ka and 6 ka, or whether the record has been disturbed by erosion/reworking remains. These issues are discussed in terms of the reliability of the quartz OSL ages, the degree of bleaching by comparison with polymineral OSL signals, and the relationship of the OSL ages to the sedimentary record.

Effect of high-dose irradiation on the optically stimulated luminescence of Al2O3:C

NASA Technical Reports Server (NTRS)

Yukihara, E. G.; Whitley, V. H.; McKeever, S. W. S.; Akselrod, A. E.; Akselrod, M. S.

2004-01-01

This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F+ -centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed. c2004 Elsevier Ltd. All rights reserved.

Image reconstruction algorithm for optically stimulated luminescence 2D dosimetry using laser-scanned Al2O3:C and Al2O3:C,Mg films

NASA Astrophysics Data System (ADS)

Ahmed, M. F.; Schnell, E.; Ahmad, S.; Yukihara, E. G.

2016-10-01

The objective of this work was to develop an image reconstruction algorithm for 2D dosimetry using Al2O3:C and Al2O3:C,Mg optically stimulated luminescence (OSL) films imaged using a laser scanning system. The algorithm takes into account parameters associated with detector properties and the readout system. Pieces of Al2O3:C films (~8 mm  ×  8 mm  ×  125 µm) were irradiated and used to simulate dose distributions with extreme dose gradients (zero and non-zero dose regions). The OSLD film pieces were scanned using a custom-built laser-scanning OSL reader and the data obtained were used to develop and demonstrate a dose reconstruction algorithm. The algorithm includes corrections for: (a) galvo hysteresis, (b) photomultiplier tube (PMT) linearity, (c) phosphorescence, (d) ‘pixel bleeding’ caused by the 35 ms luminescence lifetime of F-centers in Al2O3, (e) geometrical distortion inherent to Galvo scanning system, and (f) position dependence of the light collection efficiency. The algorithm was also applied to 6.0 cm  ×  6.0 cm  ×  125 μm or 10.0 cm  ×  10.0 cm  ×  125 µm Al2O3:C and Al2O3:C,Mg films exposed to megavoltage x-rays (6 MV) and 12C beams (430 MeV u-1). The results obtained using pieces of irradiated films show the ability of the image reconstruction algorithm to correct for pixel bleeding even in the presence of extremely sharp dose gradients. Corrections for geometric distortion and position dependence of light collection efficiency were shown to minimize characteristic limitations of this system design. We also exemplify the application of the algorithm to more clinically relevant 6 MV x-ray beam and a 12C pencil beam, demonstrating the potential for small field dosimetry. The image reconstruction algorithm described here provides the foundation for laser-scanned OSL applied to 2D dosimetry.

Thermally-assisted optically stimulated luminescence from deep electron traps in α-Al2O3:C,Mg

NASA Astrophysics Data System (ADS)

Kalita, J. M.; Chithambo, M. L.; Polymeris, G. S.

2017-07-01

We report thermally-assisted optically stimulated luminescence (TA-OSL) in α-Al2O3:C,Mg. The OSL was measured at elevated temperatures between 50 and 240 °C from a sample preheated to 500 °C after irradiation to 100 Gy. That OSL could be measured even after the preheating is direct evidence of the existence of deep electron traps in α-Al2O3:C,Mg. The TA-OSL intensity goes through a peak with measurement temperature. The initial increase is ascribed to thermal assistance to optical stimulation whereas the subsequent decrease in intensity is deduced to reflect increasing incidences of non-radiative recombination, that is, thermal quenching. The activation energy for thermal assistance corresponding to a deep electron trap was estimated as 0.667 ± 0.006 eV whereas the activation energy for thermal quenching was calculated as 0.90 ± 0.04 eV. The intensity of the TA-OSL was also found to increase with irradiation dose. The dose response is sublinear from 25 to 150 Gy but saturates with further increase of dose. The TA-OSL dose response has been discussed by considering the competition for charges at the deep traps. This study incidentally shows that TA-OSL can be effectively used in dosimetry involving large doses.

Extending the upper age limit for luminescence dating using the thermally transferred optically stimulated luminescence signal from quartz

NASA Astrophysics Data System (ADS)

Duller, Geoff A. T.; Wintle, Ann G.

2010-05-01

The optically stimulated luminescence (OSL) signal from quartz has been exploited for the last 20 years to date heated and unheated materials. While methods based on this signal have been extremely successful and are now widely adopted in laboratories around the world, growth of the signal with dose is affected by saturation and this commonly limits application to samples with equivalent doses of ~100 to 300 Gy. In most environments this limits application of the method to the last 100-150 ka. Studies of OSL from quartz in the late 1980's showed that if the OSL signal from a sample was reduced to background level by measurement, and the sample then heated, further optical stimulation gave a significant signal. This recuperated OSL was viewed as a problem to be avoided, particularly for young samples. Three years ago papers were published showing that this recuperated signal has the potential to be valuable in dosimetry, and in particular that the signal continues to grow to doses in excess of 10,000 Gy offering the possibility of extending the age range over which quartz can be used to as much as 1 Ma. The first work on this signal was undertaken on fine grain quartz extracted from Chinese loess, and ages back to the Brunhes-Matuyama boundary were obtained. The signal is now commonly referred to as thermally transferred optically stimulated luminescence (TT-OSL). Intense research on the signal has focussed on a number of areas, including, (a) understanding the origin of the charge measured in TT-OSL, (b) improving methods for measuring the TT-OSL signal, and (c) developing protocols for using TT-OSL in dose estimation, and these are reviewed in this presentation.

Luminescence properties of Eu{sup 2+} doped SrB{sub 4}O{sub 7} phosphor for radiation dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palan, C.B., E-mail: chetanpalan27@yahoo.in; Bajaj, N.S.; Omanwar, S.K.

Highlights: • Report TL/OSL properties of SrB{sub 4}O{sub 7}:Eu{sup 2+} under beta irradiations. • OSL Sensitivity was about 33% than that of commercially available α-Al{sub 2}O{sub 3.} • TL glow peaks was appear at 305° C and TL sensitivity about 200 times higher than TLD-500. • OSL decay pattern was faster than α- Al{sub 2}O{sub 3}:C and dose response was linear nature. - Abstract: In this report, we presented the TL/OSL properties of Eu doped SrB{sub 4}O{sub 7} phosphor under β-irradiation. This phosphor was synthesized by using solid state method. The phosphor shows OSL sensitivity about 33% than that ofmore » commercially available α-Al{sub 2}O{sub 3}: C phosphor. CW-OSL curve possess two components having photoionization cross-sections 0.707 × 10{sup −17} and 18.58 × 10{sup −17} cm{sup 2} respectively and TL sensitivity about 200 times higher than TLD-500. The kinetic parameters such as activation energy, frequency factor and order of kinetics of TL curve were calculated by using peak shape method. In TL/OSL mode dose-response was almost linear in the range of measurements. The MDD was found to be 1.26 mGy with 3σ of background. Also reusability studies showed the phosphor can be reused for 10 cycles with 1% change in the OSL output. The PL spectra of SrB{sub 4}O{sub 7} showed emission in NUV region when excited with 318 nm under UV source.« less

INTEGRATED CIRCUITS FROM MOBILE PHONES AS POSSIBLE EMERGENCY OSL/TL DOSIMETERS.

PubMed

Sholom, S; McKeever, S W S

2016-09-01

In this article, optically stimulated luminescence (OSL) data are presented from integrated circuits (ICs) extracted from mobile phones. The purpose is to evaluate the potential of using OSL from components in personal electronic devices such as smart phones as a means of emergency dosimetry in the event of a large-scale radiological incident. ICs were extracted from five different makes and models of mobile phone. Sample preparation procedures are described, and OSL from the IC samples following irradiation using a (90)Sr/(90)Y source is presented. Repeatability, sensitivity, dose responses, minimum measureable doses, stability and fading data were examined and are described. A protocol for measuring absorbed dose is presented, and it was concluded that OSL from these components is a viable method for assessing dose in the days following a radiological incident. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Optically stimulated luminescence of borate glasses containing magnesia, quicklime, lithium and potassium carbonates

NASA Astrophysics Data System (ADS)

Valença, J. V. B.; Silveira, I. S.; Silva, A. C. A.; Dantas, N. O.; Antonio, P. L.; Caldas, L. V. E.; d'Errico, F.; Souza, S. O.

2017-11-01

The OSL characteristics of three different borate glass matrices containing magnesia (LMB), quicklime (LCB) or potassium carbonate (LKB) were examined. Five different formulations for each composition were produced using a melt-quenching method and analyzed in terms of both dose-response curves and OSL shape decay. The samples were irradiated using a 90Sr/90Y beta source with doses up to 30 Gy. Dose-response curves were plotted using the initial OSL intensity as the chosen parameter. The OSL analysis showed that LKB glasses are the most sensitive to beta irradiation. For the most sensitive LKB composition, the irradiation process was also done using a 60Co gamma source in a dose range from 200 to 800 Gy. In all cases, no saturation was observed. A fitting process using a three-term exponential function was performed for the most sensitive formulations of each composition, which suggested a similar behavior in the OSL decay.

New data on OSL dating of Early Khalynian deposits of Northern Caspian

NASA Astrophysics Data System (ADS)

Sychev, Nikita; Yanina, Tamara; Svitoch, Alexander; Kurbanov, Redzhep; Badyukova, Ekaterina

2016-04-01

Ponto-Caspian region is the key region the study of which can provide information about the paleogeographic history of the central Eurasia, particularly revealing the history of the East European Plain, the Caucasus and Central Asia. However, despite the long history of the study, today there is no accepted general stratigraphic scheme of the Caspian Sea. One of the most interesting and important stages of Late Pleistocene history of Caspian is Khalynian transgression which is divided into two major phases: early and ate. In the Caspian lowland Lower Khalynian stage are represented by a unique type of deposit - "chocolate clays". A distinctive feature of these sediments is widely distributed among Lower Khalynian deposits of Northern Caspian and the Volga region. All clay deposits are confined to the diverse origins of depression before-Khalynian relief. Chocolate clays formation consists of facies: mono-clay (typological), layered, sand- and silty-clay (Svitoch, Yanina, 1997). Determining the age of chocolate clays by optically stimulated luminescence (OSL) in our view will allow bettering the understanding of their genesis. Age of chocolate clays of Lower Volga was widely dated using the radiocarbon. However, the existing chronology is controversial, raises a number of issues, primarily due to the material of which are used for dating - thin shells of Caspian mollusks of the Didacna Eichw. genus, which are characterized by a significant isotopic exchange with the enclosing sediments (Arslanov, 2015). Lower Volga region is characterized by very complex geological structure of the Late Pleistocene deposits (alternating continental aeolian, alluvial and slope sediments with marine Caspian deposits of different age). There are many conflicting opinions, not only with respect to paleogeographic features of the area, but also to its precise chronology. The differences in opinion over the age of the individual stages of development of the Caspian Sea (transgressions and regressions) reaches high values (Arslanov, 2015). Therefore in this paper we describe the new OSL-dating results of Khalynian transgression sediments. Two key sections were selected for study: Srednaya Akhtuba and Nizhneye Zaymische. The first section - Srednaya Akhtuba is located in the slope of the ravine, cutting through the marine plain, 1 km above the bridge across the Akhtuba river. Nizhneye Zaymische located in the slope of Volga-Akhtuba valley, cutting through the marine Khalynian plain. For the dating of these deposits we used Risø OSL-reader (provided by Nordic luminescence Lab and DTU), and standard SAR protocol (Murray, 2004). The obtained results characterize 5 equivalent doses of chocolate clays samples. The first date was obtained for the top of the chocolate clay, one for the bottom. Accordingly, two calculated OSL-dates indicate the age of these deposits corresponding to initial stage of the first marine isotope stage (MIS-1). These dates are well correlated with the characteristics of age, obtained by radiocarbon and U-Th methods that show their high reliability. The equivalent dose obtained for chocolate clays of Nizhneye Zaimishce is 43 Gy, radiation dose in Akhtuba sediments was about 3.1 Gy per thousand years. This research was supported by the Russian Science Foundation Project 14-17-00705.

[Comparative Study of Patient Identifications for Conventional and Portable Chest Radiographs Utilizing ROC Analysis].

PubMed

Kawashima, Hiroki; Hayashi, Norio; Ohno, Naoki; Matsuura, Yukihiro; Sanada, Shigeru

2015-08-01

To evaluate the patient identification ability of radiographers, previous and current chest radiographs were assessed with observer study utilizing a receiver operating characteristics (ROCs) analysis. This study included portable and conventional chest radiographs from 43 same and 43 different patients. The dataset used in this study was divided into the three following groups: (1) a pair of portable radiographs, (2) a pair of conventional radiographs, and (3) a combination of each type of radiograph. Seven observers participated in this ROC study, which aimed to identify same or different patients, using these datasets. ROC analysis was conducted to calculate the average area under ROC curve obtained by each observer (AUCave), and a statistical test was performed using the multi-reader multi-case method. Comparable results were obtained with pairs of portable (AUCave: 0.949) and conventional radiographs (AUCave: 0.951). In a comparison between the same modality, there were no significant differences. In contrast, the ability to identify patients by comparing a portable and conventional radiograph (AUCave: 0.873) was lower than with the matching datasets (p=0.002 and p=0.004, respectively). In conclusion, the use of different imaging modalities reduces radiographers' ability to identify their patients.

Using Electronic Readers: Action Research in an Intermediate Adult ESL Class

ERIC Educational Resources Information Center

Fraser, Monica; Abbott, Marilyn

2016-01-01

The use of portable electronic reading devices in the English as a second language (ESL) classroom has the potential to positively impact learners' reading engagement and language skill development. However, due to the lack of research, few guidelines are available to inform instructors of the benefits and challenges of using these devices in ESL…

Make That to Go: Re-Engineering a Web Portal for Mobile Access

ERIC Educational Resources Information Center

Spitzer, Stephan

2012-01-01

The fact that people now live in a world of abundant portable electronic devices is important to any organization that maintains a web presence, including libraries. No longer tied to a desktop, the patrons' netbooks, tablets, ebook readers, and, of course, cellphones all become potential tools for remote access to library content. About a year…

Empowering Personalized Learning with an Interactive E-Book Learning System for Elementary School Students

ERIC Educational Resources Information Center

Huang, Yueh-Min; Liang, Tsung-Ho; Su, Yen-Ning; Chen, Nian-Shing

2012-01-01

Today various types of tablet computers are used, including iPad and Android Tablets. These individual portable digital devices can be used as e-book readers to support mobile personalized learning. Though many studies have investigated e-books by targeting undergraduate students, yet less attention has been paid to children. Therefore, an…

Are Teenagers "Really" Keen Digital Readers? Adolescent Engagement in Ebook Reading and the Relevance of Paper Books Today

ERIC Educational Resources Information Center

Merga, Margaret K.

2014-01-01

Digital reading technologies may be intuitively appealing. They offer many possibilities, including great potential for interactivity around books, portability of whole libraries in one small reading unit, and almost instant satisfaction of demand for a particular book. Though there is limited research exploring the appeal of digital reading for…

Using Technology To Combat Truancy. Number 10 in a Series of CTC Trust Publications.

ERIC Educational Resources Information Center

Haigh, Gerald

The 14 City Technology Colleges (CTCs) opened so far in Great Britain are achieving an average attendance rate of between 90 percent and 97 percent. This high level of attendance has been assisted by the use of electronic registration (role taking) devices, including smart cards, portable computers, and optical readers. This report compares…

OSL technique for studies of jasper samples

NASA Astrophysics Data System (ADS)

Teixeira, Maria Inês; Caldas, Linda V. E.

2014-02-01

Jasper samples (green, red, brown, ocean and striped) were studied in relation to their optically stimulated luminescence (OSL) dosimetric properties, in this work. Since 2000, the radiation metrology group of IPEN has studied different stones as new materials for application in high-dose dosimetry. The jasper samples were exposed to different radiation doses, using the Gamma-cell 220 system (60Co) of IPEN. Calibration curves were obtained for the jasper samples between 50 Gy and 300 kGy. The reproducibility of the OSL response and the lower detection doses were determined. All five types of jasper samples showed their usefulness as irradiation indicators and as high-dose dosimeters, using the OSL technique.

Performance of Al2O3:C optically stimulated luminescence dosimeters for clinical radiation therapy applications.

PubMed

Hu, B; Wang, Y; Zealey, W

2009-12-01

A commercial Optical Stimulated Luminescence (OSL) dosimetry system developed by Landauer was tested to analyse the possibility of using OSL dosimetry for external beam radiotherapy planning checks. Experiments were performed to determine signal sensitivity, dose response range, beam type/energy dependency, reproducibility and linearity. Optical annealing processes to test OSL material reusability were also studied. In each case the measurements were converted into absorbed dose. The experimental results show that OSL dosimetry provides a wide dose response range, good linearity and reproducibility for the doses up to 800cGy. The OSL output is linear with dose up to 600cGy range showing a maximum deviation from linearity of 2.0% for the doses above 600cGy. The standard deviation in response of 20 dosimeters was 3.0%. After optical annealing using incandescent light, the readout intensity decreased by approximately 98% in the first 30 minutes. The readout intensity, I, decreased after repeated optical annealing as a power law, given by I infinity t (-1.3). This study concludes that OSL dosimetry can provide an alternative dosimetry technique for use in in-vivo dosimetry if rigorous measurement protocols are established.

Comparison of Cottonwood Dendrochronology and Optically Stimulated Luminescence Geochronometers Along a High Plains Meandering River, Powder River, Montana, USA

NASA Astrophysics Data System (ADS)

Hasse, T. R.; Schook, D. M.

2017-12-01

Geochronometers at centennial scales can aid our understanding of process rates in fluvial geomorphology. Plains cottonwood trees (Populus deltoides ssp. Monilifera) in the high plains of the United States are known to germinate on freshly created deposits such as point bars adjacent to rivers. As the trees mature they may be partially buried (up to a few meters) by additional flood deposits. Cottonwood age gives a minimum age estimate of the stratigraphic surface where the tree germinated and a maximum age estimate for overlying sediments, providing quantitative data on rates of river migration and sediment accumulation. Optically Stimulated Luminescence (OSL) of sand grains can be used to estimate the time since the sand grains were last exposed to sunlight, also giving a minimum age estimate of sediment burial. Both methods have disadvantages: Browsing, partial burial, and other damage to young cottonwoods can increase the time required for the tree to reach a height where it can be sampled with a tree corer, making the germination point a few years to a few decades older than the measured tree age; fluvial OSL samples can have inherited age (when the OSL age is older than the burial age) if the sediment was not completely bleached prior to burial. We collected OSL samples at 8 eroding banks of the Powder River Montana, and tree cores at breast height (±1.2 m) from cottonwood trees growing on the floodplain adjacent to the OSL sample locations. Using the Minimum Age Model (MAM) we found that OSL ages appear to be 500 to 1,000 years older than the adjacent cottonwood trees which range in age (at breast height) from 60 to 185 years. Three explanations for this apparent anomaly in ages are explored. Samples for OSL could be below a stratigraphic unconformity relative to the cottonwood germination elevation. Shallow samples for OSL could be affected by anthropogenic mixing of sediments due to plowing and leveling of hay fields. The OSL samples could have significant inherited ages due to partial bleaching during sediment transport in this high plains river with high suspended sediment loads. The dendrochronology of the adjacent cottonwood trees then offers an independent measurement of the inherited age of the OSL samples.

A 3D-Printed, Portable, Optical-Sensing Platform for Smartphones Capable of Detecting the Herbicide 2,4-Dichlorophenoxyacetic Acid.

PubMed

Wang, Yijia; Zeinhom, Mohamed M A; Yang, Mingming; Sun, Rongrong; Wang, Shengfu; Smith, Jordan N; Timchalk, Charles; Li, Lei; Lin, Yuehe; Du, Dan

2017-09-05

Onsite rapid detection of herbicides and herbicide residuals in environmental and biological specimens are important for agriculture, environmental concerns, food safety, and health care. The traditional method for herbicide detection requires expensive laboratory equipment and a long turnaround time. In this work, we developed a single-stripe microliter plate smartphone-based colorimetric device for rapid and low-cost in-field tests. This portable smartphone platform is capable of screening eight samples in a single-stripe microplate. The device combined the advantages of small size (50 × 100 × 160 mm 3 ) and low cost ($10). The platform was calibrated by using two different dye solutions, i.e. methyl blue (MB) and rhodamine B, for the red and green channels. The results showed good correlation with results attained from a traditional laboratory reader. We demonstrated the application of this platform for detection of the herbicide 2,4-dichlorophenoxyacetic acid in the range of 1 to 80 ppb. Spiked samples of tap water, rat serum, plasma, and human serum were tested by our device. Recoveries obtained varied from 95.6% to 105.2% for all of the spiked samples using the microplate reader and from 93.7% to 106.9% for all of the samples using the smartphone device. This work validated that the smartphone optical-sensing platform is comparable to the commercial microplate reader; it is eligible for onsite, rapid, and low-cost detection of herbicides for environmental evaluation and biological monitoring.

A 3D-Printed, Portable, Optical-Sensing Platform for Smartphones Capable of Detecting the Herbicide 2,4-Dichlorophenoxyacetic Acid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Yijia; Zeinhom, Mohamed M. A.; Yang, Mingming

Onsite rapid detection of herbicide and herbicide residuals in environmental and biological specimens is important for agriculture, environment, food safety, and health care. Traditional method for herbicide detection requires expensive laboratory equipment and a long turn-round time. In this work, we developed a single-stripe microliter plate smartphone colorimetric device for rapid and low-cost in-field test. This portable smartphone platform is capable of screening 8 samples in a microplate single-stripe. The device combined the advantages of small size (50×100×160 mm3) and low cost ($10). The platform was calibrated by using two different dye solutions, i.e. methyl blue (MB) and Rhodamine B,more » for green and red channels. The results showed good correlation with results attained from a traditional laboratory reader. We demonstrated the application of this platform for an herbicide, 2,4-Dichlorophenoxyacetic acid detection in the range of 1 ppb to 80 ppb. Spiked samples of tap water, rat serum, plasma and human serum were tested by our device. Recoveries obtained varied from 95.6% to 105.2% for all spiked samples using the microplate reader and from 93.7% to 106.9% using the smartphone device. This work validated that the smartphone optical sensing platform is comparable to the commercial microplate reader, it is eligible for onsite rapid and low-cost detection of herbicide for environmental evaluation and biological monitoring.« less

MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

NASA Astrophysics Data System (ADS)

Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

2016-04-01

The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy-30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6-7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping.

MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

PubMed Central

Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

2016-01-01

The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy–30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6–7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping. PMID:27076349

Investigation of a BeO-based optically stimulated luminescence dosemeter.

PubMed

Sommer, M; Henniger, J

2006-01-01

The optical sensitivity of BeO-based luminophors has been well-known for many years. The optical stimulation of BeO with blue light is most effective. Then the dosemeters emit luminescent light in the ultraviolet-range around 325 nm. Matched on these facts a simple optically stimulated luminescence (OSL) treatment has been developed. Intense blue light-emitting diodes are used for cw-stimulation. A Hamamatsu solar blind photomultiplier detects the OSL-light. Good separation of both spectral ranges by optical filters is very important. The dosemeter has a linear dose response between approximately 20 muGy and >10 Gy. It was suggested, that a modification of stimulation conditions would allow measurements down to 1 muGy. Fading, photon energy dependence and reproducibility of OSL-signal correspond well with requirements to clinical and personal dosemeters. In addition, basic questions of the OSL-process in BeO have been investigated. A relevant point of interest was the dependency of the OSL-signal on stimulation power.

Highly sensitive Europium doped SrSO4 OSL nanophosphor for radiation dosimetry applications

NASA Astrophysics Data System (ADS)

Patle, Anita; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

2015-10-01

Highly sensitive Europium doped SrSO4 optically stimulated luminescent (OSL) phosphor was developed by synthesizing a nano phosphor which is treated at 1000 °C. Excellent OSL properties are observed in the developed phosphor and the sensitivity is found to be 1.26 times to that of the commercial Al2O3:C (Landauer Inc.) phosphor based on area integration method. The sample showed a single TL glow peak around 230 °C which is found to reduce by 47% after the OSL readout. Sublinear dose response with the saturation around 100 mGy is observed in this sample which suggests that it is extremely sensitive and hence will be suitable in detecting very low dose levels. Minimum measurable dose on the used set up is estimated to be 1.42 μGy. Practically no fading is observed for first ten days and the phosphor has excellent reusability. High sensitivity, low fading, excellent reusability will make this phosphor suitable for radiation dosimetry applications using OSL.

1997 NRL Review

DTIC Science & Technology

1997-04-01

are subsequently read out using a low- doped Glasses power, solid-state diode laser. Figure 4 shows a schematic of the OSL dosimeter . The 807-nm A.L...Huston, S, Rychnovsky, and B.L. Justus (near infrared) diode laser light stimulates blue OSL Optical Sciences Division emission from the dosimeter , and...The sensitivity of the hole pairs become trapped and may persist until prototype OSL dosimeter exceeds that of the stimulated to luminesce by the

Emergency EPR and OSL dosimetry with table vitamins and minerals.

PubMed

Sholom, S; McKeever, S W S

2016-12-01

Several table vitamins, minerals and L-lysine amino acid have been preliminarily tested as potential emergency dosemeters using electron paramagnetic resonance (EPR) and optically stimulated luminescence (OSL) techniques. Radiation-induced EPR signals were detected in samples of vitamin B2 and L-lysine while samples of multivitamins of different brands as well as mineral Mg demonstrated prominent OSL signals after exposure to ionizing radiation doses. Basic dosimetric properties of the radiation-sensitive substances were studied, namely dose response, fading of the EPR or OSL signals and values of minimum measurable doses (MMDs). For EPR-sensitive samples, the EPR signal is converted into units of dose using a linear dose response and correcting for fading using the measured fading dependence. For OSL-sensitive materials, a multi-aliquot, enhanced-temperature protocol was developed to avoid the problem of sample sensitization and to minimize the influence of signal fading. The sample dose in this case is also evaluated using the dose response and fading curves. MMDs of the EPR-sensitive samples were below 2 Gy while those of the OSL-sensitive materials were below 500 mGy as long as the samples are analyzed within 1 week after exposure. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Direct evidence for the participation of band-tails and excited-state tunnelling in the luminescence of irradiated feldspars

NASA Astrophysics Data System (ADS)

Poolton, N. R. J.; Kars, R. H.; Wallinga, J.; Bos, A. J. J.

2009-12-01

The significance and extent of band-tail states in the luminescence and dosimetry properties of natural aluminosilicates (feldspars) is investigated by means of studies using low temperature (10 K) irradiation and optically stimulated luminescence (OSL) stimulation spectroscopy, and thermoluminescence (TL) in the range 10-200 K, made in comparison with high temperature (300 K) irradiation and photo-transferred OSL and TL investigations undertaken at low temperature. These measurements allow mappings of the band-tails to be made; they are found to be ~0.4 eV in extent in the typical materials studied. Furthermore, by populating charge trapping centres at high temperature (300 K) and monitoring the OSL stimulation spectra at temperatures in the range 10-300 K, clear evidence is presented for the presence of both thermally activated and non-thermally activated OSL processes; it is argued that the former result from thermally activated hopping through the band-tail states, whilst the latter are due to tunnelling processes, either from the excited state of the OSL centres or through the tail states. The spectral measurements are supported by analysis of the temporal dependence of the OSL signals, which correspond to either tunnelling or general order kinetic decay processes.

A Study on Mobile Learning as a Learning Style in Modern Research Practice

ERIC Educational Resources Information Center

Joan, D. R. Robert

2013-01-01

Mobile learning is a kind of learning that takes place via a portable handheld electronic device. It also refers to learning via other kinds of mobile devices such as tablet computers, net-books and digital readers. The objective of mobile learning is to provide the learner the ability to assimilate learning anywhere and at anytime. Mobile devices…

All is not lost: deriving a top-down mass budget of plastic at sea

NASA Astrophysics Data System (ADS)

Koelmans, Albert A.; Kooi, Merel; Lavender Law, Kara; van Sebille, Erik

2017-11-01

Understanding the global mass inventory is one of the main challenges in present research on plastic marine debris. Especially the fragmentation and vertical transport processes of oceanic plastic are poorly understood. However, whereas fragmentation rates are unknown, information on plastic emissions, concentrations of plastics in the ocean surface layer (OSL) and fragmentation mechanisms is available. Here, we apply a systems engineering analytical approach and propose a tentative ‘whole ocean’ mass balance model that combines emission data, surface area-normalized plastic fragmentation rates, estimated concentrations in the OSL, and removal from the OSL by sinking. We simulate known plastic abundances in the OSL and calculate an average whole ocean apparent surface area-normalized plastic fragmentation rate constant, given representative radii for macroplastic and microplastic. Simulations show that 99.8% of the plastic that had entered the ocean since 1950 had settled below the OSL by 2016, with an additional 9.4 million tons settling per year. In 2016, the model predicts that of the 0.309 million tons in the OSL, an estimated 83.7% was macroplastic, 13.8% microplastic, and 2.5% was < 0.335 mm ‘nanoplastic’. A zero future emission simulation shows that almost all plastic in the OSL would be removed within three years, implying a fast response time of surface plastic abundance to changes in inputs. The model complements current spatially explicit models, points to future experiments that would inform critical model parameters, and allows for further validation when more experimental and field data become available.

The Influence of Added Mass on Optimal Step Length in Running.

PubMed

Reenalda, Jasper; Maas, Maurice T F; de Koning, Jos J

2016-10-01

To examine the influence of induced changes in the morphology of the leg by adding mass on the optimal step length (OSL) in experienced runners to get more insight into parameters that influence preferred step length (PSL) and OSL. Thirteen experienced male runners (mean age 26.9 ± 6.1 y, height 183.7 ± 7.1 cm, mass 71.8 ± 5.9 kg) ran on a treadmill in 3 different conditions: unloaded (UL), loaded with 2 kg mass at the ankles (MA), and loaded with 2 kg mass at the hips (MH) at 7 different step lengths (SLs). SL deviations were expressed as deviations in relative leg length (%LL) from the individual PSL: 0%LL, ±5%LL, ±10%LL, and ±15%LL. Trials lasted 8 min, and 8 min of rest was given between trials. Oxygen uptake (V̇O 2 ) was expressed as a fraction of V̇O 2 at PSL + 0%LL in the unloaded condition (%V̇O 2 ). The %SL with the lowest value of %V̇O 2 was considered the OSL for this group of participants. OSL at the UL condition was 6% shorter than PSL. The MA condition resulted in a 7%LL larger OSL than at UL and MH (P < .05). The mass distribution of the leg is a determinant of the OSL. As a consequence of the added mass to the ankles, OSL was 7%LL longer. Morphological characteristics of the leg might therefore play an important role in determining the runner's individual optimal SL.

High resolution optically stimulated luminescence dating of a sediment core from the southwestern Sea of Okhotsk

NASA Astrophysics Data System (ADS)

Sugisaki, S.; Buylaert, J. P.; Murray, A. S.; Harada, N.; Kimoto, K.; Okazaki, Y.; Sakamoto, T.; Iijima, K.; Tsukamoto, S.; Miura, H.; Nogi, Y.

2012-05-01

Optically stimulated luminescence (OSL) dating is now widely accepted as a chronometer for terrestrial sediment. More recently, it has been suggested that OSL may also be useful in the dating of deep-sea marine sediments. In this paper, we test the usefulness of high resolution quartz OSL dating in application to a 19 m marine sediment core (MR0604-PC04A) taken from the southwestern Sea of Okhotsk, immediately to the north of Hokkaido, Japan. Fine-grained quartz (4 to 11μm) was chosen as the dosimeter, and a single-aliquot regenerative-dose protocol was used for the determination of equivalent dose (De), with stimulation by both infrared and blue light. The suitability of the measurement procedure was confirmed using dose recovery tests. A high resolution record (˜2 OSL ages/m) identified clear sedimentation rate changes down the core. The OSL ages are significantly dependent on the water content model chosen; two alternative interpretations are discussed, and the geologically preferred model identified. However, ages resulting from the observed (non-modeled) water content lie closest to the available radiocarbon ages (in the range back to 20 ka). Our OSL ages confirm the known high sedimentation rates in this locality, and for the first time demonstrate clear differences in sedimentation rate before, during and after deglaciation. Although the apparent accuracy of single sample ages is not always consistent with expectations, average ages are accurate, and our data show that OSL dating can be a powerful method for establishing high resolution marine chronologies.

Impedance measurements of the human cochlear partition

NASA Astrophysics Data System (ADS)

Raufer, Stefan; Nakajima, Hideko H.

2018-05-01

The cochlea is a mechanical frequency analyzer, owing its characteristics to the impedance of the cochlear partition. In humans, the impedance of the partition has not been measured directly, and estimates of the stiffness (a principal component of the impedance) are based on loose assumptions. In this study, we examine not only the stiffness of the basilar membrane (BM), but also the osseous spiral lamina (OSL), which, in human, vibrates substantially. We hypothesize that the OSL contributes significantly to the volume stiffness of the cochlear partition (CP). We measured velocities of the BM and OSL at different radial locations 1 mm from the base of the cochlea in a fresh human cadaveric specimen. Simultaneously, we measured intracochlear pressures on the other side of the partition, in scala vestibuli. With the velocity and pressure measurements we can estimate the specific acoustic impedance of the BM and OSL (Z = p/v). At frequencies well below the resonant frequency, the stiffness of these structures can be extracted by multiplying the impedance by the radian frequency. The specific acoustic stiffness was found to be 1.2 GPa/m on the BM, 6 GPa/m at the juncture where the BM attaches to the OSL, and 10 GPa/m at the midpoint of the OSL. A beam model, appropriate to model the radial motion of the BM in guinea pig or gerbil, cannot describe the displacement of the human CP in the base. Instead, we find that the OSL is hinged near the modiolus and vibrates significantly near the connection to the more compliant BM, contributing greatly the volume compliance of the CP.

The effect of pre-dose on thermally and optically stimulated luminescence from α-Al2O3:C,Mg and α-Al2O3:C.

PubMed

Kalita, J M; Chithambo, M L

2018-06-15

We report the effect of pre-dose on the thermoluminescence (TL) and optically stimulated luminescence (OSL) dose response of α-Al 2 O 3 :C,Mg and α-Al 2 O 3 :C. Before any luminescence measurement, the samples were irradiated with different doses, namely 100, 500 and 1000 Gy to populate the deep electron traps. This is the pre-dose. The results from TL and OSL studies are compared with results from samples used without any pre-measurement dose. The TL glow curves and OSL decay curves of α-Al 2 O 3 :C,Mg recorded after pre-doses of 100, 500 and 1000 Gy are identical to those from a sample used without any pre-dose. Further, the TL and OSL dose response of all α-Al 2 O 3 :C,Mg samples are similar regardless of pre-dose. In comparison, the TL glow curves and OSL decay curves of α-Al 2 O 3 :C are influenced by pre-dose. We conclude that the differences in the TL and OSL dose response of various pre-dosed samples of α-Al 2 O 3 :C are due to the concentration of charge in the deep traps. On the other hand, owing to the lower concentration of such deep traps in α-Al 2 O 3 :C,Mg, the TL or OSL dose responses are not affected by pre-dose in this material. Copyright © 2018 Elsevier Ltd. All rights reserved.

Optical Encoding Technology for Viral Screening Panels Final Report CRADA No TC02132.0

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lenhoff, R.; Haushalter, R.

This was a collaborative effort between Lawrence Livermore National Security, LLC, Lawrence Livermore National Laboratory (LLNL) and Parallel Synthesis Technologies, Inc. (PSTI), to develop Optical Encoding Technology for Viral Screening Panels. The goal for this effort was to prepare a portable bead reader system that would enable the development of viral and bacterial screening panels which could be used for the detection of any desired set of bacteria or viruses in any location. The main objective was to determine if the combination of a bead-based, PCR suspension array technology, formulated from Parallume encoded beads and PSTI’s multiplex assay reader systemmore » (MARS), could provide advantages in terms of the number of simultaneously measured samples, portability, ruggedness, ease of use, accuracy, precision or cost as compared to the Luminexbased system developed at LLNL. The project underwent several no cost extensions however the overall goal of demonstrating the utility of this new system was achieved. As a result of the project a significant change to the type of bead PSTI used for the suspension system was implemented allowing better performance than the commercial Luminex system.« less

SU-F-18C-09: Assessment of OSL Dosimeter Technology in the Validation of a Monte Carlo Radiation Transport Code for CT Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carver, D; Kost, S; Pickens, D

Purpose: To assess the utility of optically stimulated luminescent (OSL) dosimeter technology in calibrating and validating a Monte Carlo radiation transport code for computed tomography (CT). Methods: Exposure data were taken using both a standard CT 100-mm pencil ionization chamber and a series of 150-mm OSL CT dosimeters. Measurements were made at system isocenter in air as well as in standard 16-cm (head) and 32-cm (body) CTDI phantoms at isocenter and at the 12 o'clock positions. Scans were performed on a Philips Brilliance 64 CT scanner for 100 and 120 kVp at 300 mAs with a nominal beam width ofmore » 40 mm. A radiation transport code to simulate the CT scanner conditions was developed using the GEANT4 physics toolkit. The imaging geometry and associated parameters were simulated for each ionization chamber and phantom combination. Simulated absorbed doses were compared to both CTDI{sub 100} values determined from the ion chamber and to CTDI{sub 100} values reported from the OSLs. The dose profiles from each simulation were also compared to the physical OSL dose profiles. Results: CTDI{sub 100} values reported by the ion chamber and OSLs are generally in good agreement (average percent difference of 9%), and provide a suitable way to calibrate doses obtained from simulation to real absorbed doses. Simulated and real CTDI{sub 100} values agree to within 10% or less, and the simulated dose profiles also predict the physical profiles reported by the OSLs. Conclusion: Ionization chambers are generally considered the standard for absolute dose measurements. However, OSL dosimeters may also serve as a useful tool with the significant benefit of also assessing the radiation dose profile. This may offer an advantage to those developing simulations for assessing radiation dosimetry such as verification of spatial dose distribution and beam width.« less

Surface dose measurements with commonly used detectors: a consistent thickness correction method.

PubMed

Reynolds, Tatsiana A; Higgins, Patrick

2015-09-08

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30-360) with other parallel plate chambers RMI-449 (Attix), Capintec PS-033, PTW 30-329 (Markus) and Memorial. Measurements of surface dose for 6MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (-0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid-state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three-detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth-dose curves and is not recommended for these types of measurements.

SU-E-T-91: Correction Method to Determine Surface Dose for OSL Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reynolds, T; Higgins, P

Purpose: OSL detectors are commonly used in clinic due to their numerous advantages, such as linear response, negligible energy, angle and temperature dependence in clinical range, for verification of the doses beyond the dmax. Although, due to the bulky shielding envelope, this type of detectors fails to measure skin dose, which is an important assessment of patient ability to finish the treatment on time and possibility of acute side effects. This study aims to optimize the methodology of determination of skin dose for conventional accelerators and a flattening filter free Tomotherapy. Methods: Measurements were done for x-ray beams: 6 MVmore » (Varian Clinac 2300, 10×10 cm{sup 2} open field, SSD = 100 cm) and for 5.5 MV (Tomotherapy, 15×40 cm{sup 2} field, SAD = 85 cm). The detectors were placed at the surface of the solid water phantom and at the reference depth (dref=1.7cm (Varian 2300), dref =1.0 cm (Tomotherapy)). The measurements for OSLs were related to the externally exposed OSLs measurements, and further were corrected to surface dose using an extrapolation method indexed to the baseline Attix ion chamber measurements. A consistent use of the extrapolation method involved: 1) irradiation of three OSLs stacked on top of each other on the surface of the phantom; 2) measurement of the relative dose value for each layer; and, 3) extrapolation of these values to zero thickness. Results: OSL measurements showed an overestimation of surface doses by the factor 2.31 for Varian 2300 and 2.65 for Tomotherapy. The relationships: SD{sup 2300} = 0.68 × M{sup 2300}-12.7 and SDτoμo = 0.73 × Mτoμo-13.1 were found to correct the single OSL measurements to surface doses in agreement with Attix measurements to within 0.1% for both machines. Conclusion: This work provides simple empirical relationships for surface dose measurements using single OSL detectors.« less

An Analysis of Emergency Department Overcrowding at The Johns Hopkins Hospital

DTIC Science & Technology

2001-06-20

Jefferson 3rd floor (JEF3), Medical Care Progressive Unit ( MPC4 ), Nelson 4th floor (NEL4), Osler 4th floor (OSL4), Osler 5th floor (OSL5), and Osler...ranged from a low of 73.78% for OSL5 to a high of 94.60% for JEF3. The LOS for the DOM units ranged from 2.89 days for HAL5 to 10.39 days for MPC4

SU-E-T-592: OSL Response of Al2O3:C Detectors Exposed to Therapeutic Proton Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Granville, DA; Flint, DB; Sawakuchi, GO

Purpose: To characterize the response of Al{sub 2}O{sub 3}:C optically stimulated luminescence (OSL) detectors (OSLDs) exposed to therapeutic proton beams of differing beam quality. Methods: We prepared Al{sub 2}O{sub 3}:C OSLDs from the same material as commercially available nanoDot dosimeters (Landauer, Inc). We irradiated the OSLDs in modulated proton beams of varying quality, as defined by the residual range. An absorbed dose to water of 0.2 Gy was delivered to all OSLDs with the residual range values varying from 0.5 to 23.5 cm (average LET in water from ∼0.5 to 2.5 keV/µm). To investigate the beam quality dependence of differentmore » emission bands within the OSL spectrum, we performed OSLD readouts using both continuous-wave stimulation (CW-OSL) and pulsed stimulation (P-OSL) with two sets of optical filters (Hoya U-340 and Kopp 5113). For all readout modes, the relative absorbed dose sensitivity ( S{sub rel}) for each beam quality was calculated using OSLDs irradiated in a 6 MV photon beam as a reference. Results: We found that the relative absorbed dose sensitivity was highly dependent on both readout mode and integration time of the OSL signal. For CW-OSL signals containing only the blue emission band, S{sub rel} was between 0.85 and 0.94 for 1 s readouts and between 0.82 and 0.93 for 10 s readouts. Similarly, for P-OSL readouts containing only the blue emission band S{sub rel} ranged from 0.86 to 0.91, and 0.82 to 0.93 for 1 s and 10 s readouts, respectively. For OSLD signals containing only the UV emission band, S{sub rel} ranged from 1.00 to 1.46, and 0.97 to 1.30 for P-OSL readouts of 1 s and 10 s, respectively. Conclusion: For measurements of absorbed dose using Al{sub 2}O{sub 3}:C OSLDs in therapeutic proton beams, dependence on beam quality was smallest for readout protocols that selected the blue emission band with small integration times. DA Granville received financial support from the Natural Sciences and Engineering Research Council of Canada.« less

Colorimetric detection for paper-based biosensing applications

NASA Astrophysics Data System (ADS)

Brink, C.; Joubert, T.-H.

2016-02-01

Research on affordable point-of-care health diagnostics is rapidly advancing1. Colorimetric biosensor applications are typically qualitative, but recently the focus has been shifted to quantitative measurements2,3. Although numerous qualitative point-of-care (POC) health diagnostic devices are available, the challenge exists of developing a quantitative colorimetric array reader system that complies with the ASSURED (Affordable, Sensitive, Specific, User-friendly, Rapid and Robust, Equipment-free, Deliverable to end-users) principles of the World Health Organization4. This paper presents a battery powered 8-bit tonal resolution colorimetric sensor circuit for paper microfluidic assays using low cost photo-detection circuitry and a low-power LED light source. A colorimetric 3×3-pixel array reader was developed for rural environments where resources and personnel are limited. The device sports an ultralow-power E-ink paper display. The colorimetric device includes integrated GPS functionality and EEPROM memory to log measurements with geo-tags for possible analysis of regional trends. The device competes with colour intensity measurement techniques using smartphone cameras, but proves to be a cheaper solution, compensating for the typical performance variations between cameras of different brands of smartphones. Inexpensive methods for quantifying bacterial assays have been shown using desktop scanners, which are not portable, and cameras, which suffer severely from changes in ambient light in different environments. Promising colorimetric detection results have been demonstrated using devices such as video cameras5, digital colour analysers6, flatbed scanners7 or custom portable readers8. The major drawback of most of these methods is the need for specialized instrumentation and for image analysis on a computer.

Use of OSL dating to establish the stratigraphic framework of Quaternary eolian sediments, Anton scarp upper trench, Northeastern Colorado High Plains, USA

USGS Publications Warehouse

Mahan, S.A.; Noe, D.C.; McCalpin, J.P.

2009-01-01

This paper contains the results of the optically stimulated luminescence (OSL) dating used to establish stratigraphic ages and relationships of eolian sediments in a trench in northeastern Colorado, USA. This trench was located in the upper face of the Anton scarp, a major topographic lineament trending NW-SE for a distance of 135 km, in anticipation of intersecting near-surface faulting. The trench was 180 m long, 4.5-6.0 m deep, and exposed 22 m of stratigraphic section, most of which dipped gently west and was truncated by gulley channeling at the face of the scarp. No direct evidence of faulting was found in the upper trench. The stratigraphy from the trench was described, mapped and dated using OSL on quartz and potassium feldspar, and 14C obtained from woody material. OSL dating identified two upper loess units as Peoria Loess and Gilman Canyon Loess, deposited between 16 and 30 ka ago. The bottom layers of the trench were substantially older, giving OSL ages in excess of 100 ka. These older ages are interpreted as underestimates, owing to saturation of the fast component of OSL. Using OSL and 14C dating, we can constrain the erosion and down cutting of the scarp face as occurring between 16 and 5.7 ka. As the trenching investigation continues in other parts of the scarp face, the results of this preliminary study will be of importance in relating the ages of the strata that underlie different parts of the scarp, and in determining whether Quaternary faulting was a mechanism that contributed to the formation of this regional geomorphic feature.

Magnetic resonance imaging, ultrasonography and histology of the suspensory ligament origin: a comparative study of normal anatomy of warmblood horses.

PubMed

Bischofberger, A S; Konar, M; Ohlerth, S; Geyer, H; Lang, J; Ueltschi, G; Lischer, C J

2006-11-01

The diagnosis of lameness caused by proximal metacarpal and metatarsal pain can be challenging. Magnetic resonance imaging (MRI) offers the possibility for further diagnosis but there have been no studies on the normal MRI appearance of the origin of the suspensory ligament (OSL) in conjunction with ultrasonography and histology. To describe the MRI appearance of the OSL in fore- and hindlimbs of sound horses and compare it to the ultrasonographic and histological appearance. The findings can be used as reference values to recognise pathology in the OSL. The OSL in the fore- and hindlimbs of 6 sound horses was examined by ultrasonography prior to death, and MRI and histology post mortem. Qualitative evaluation and morphometry of the OSL were performed and results of all modalities compared. Muscular tissue, artefacts, variable SL size and shape complicated ultrasonographic interpretation. In MRI and histology the forelimb OSL consisted of 2 portions, the lateral being significantly thicker than medial. The hindlimb SL had a single large area of origin. In fore- and hindlimbs, the amount of muscular tissue was significantly larger laterally than medially. Overall SL measurements using MRI were significantly higher than using histology and ultrasonography and histological higher than ultrasonographic measurements. Morphologically, there was a good correlation between MRI and histology. MRI provides more detailed information than ultrasonography regarding muscle fibre detection and OSL dimension and correlates morphologically well with histology. Therefore, ultrasonographic results should be regarded with caution. MRI may be a diagnostic aid when other modalities fail to identify clearly the cause of proximal metacarpal and metatarsal pain; and may improve selection of adequate therapy and prognosis for injuries in this region.

Influence of carbon on the thermoluminescence and optically stimulated luminescence of α-Al2O3:C crystals

NASA Astrophysics Data System (ADS)

Yang, Xin-Bo; Li, Hong-Jun; Bi, Qun-Yu; Cheng, Yan; Tang, Qiang; Xu, Jun

2008-12-01

α-Al2O3:C crystal shows excellent thermoluminescence (TL) and optically stimulated luminescence (OSL) properties but the real role carbon plays in this crystal is still not clearly understood so far. In this work, α-Al2O3:C crystal doping with different amounts of carbon were grown by the temperature gradient technique, and TL and OSL properties of as-grown crystals were investigated. Additionally, a mechanism was proposed to explain the role of carbon in forming the TL and OSL properties of α-Al2O3:C. TL and OSL intensities of as-grown crystals increase with the increasing amount of carbon doping in the crystal, but no shift is found in the glow peak location at 465 K. As the amount of carbon doping in the crystals decreases, OSL decay rate becomes faster. With the increase in heating rate, the integral TL response of as-grown crystals decreases and glow peak shifts to higher temperatures. TL response decrease rate increases with the increasing amount of carbon doping in the crystals. All the TL and OSL response curves of as-grown crystals show linear-sublinear-saturation characteristic, and OSL dose response exhibits higher sensitivity and wider linear dose range than that of TL. The crystal doping with 5000 ppm carbon shows the best dosimetric properties. Carbon plays the role of a dopant in α-Al2O3:C crystal and four-valent carbon anions replace the two-valent anions of oxygen during the crystal growth process, and large amounts of oxygen vacancies were formed, which corresponds to the high absorption coefficient of F and F+ centers in the crystals.

Synthesis and evaluation of new antimalarial analogues of quinoline alkaloids derived from Cinchona ledgeriana Moens ex Trimen.

PubMed

Park, Byeoung-Soo; Kim, Dae-Young; Rosenthal, Philip J; Huh, Sun-Chul; Lee, Belinda J; Park, Eun -u; Kim, Sung-Min; Kim, Jang-Eok; Kim, Mi-Hee; Huh, Tae-Lin; Choi, Young-Jae; Suh, Ki-Hyung; Choi, Won-Sik; Lee, Sung-Eun

2002-05-20

In the course of attempts to develop antimalarial drugs, we have designed and synthesized a series of quinoline alkaloide derivatives. Three of them, N-(4-methoxy-3,5-di-tert-butylbenzyl)cinchonidinium bromide (OSL-5), O-benzyl-N-(3,5-di-tert-butyl-4-methoxybenzyl)cinchonidinium bromide (OSL-7), and N-(3,5-di-tert-butyl-4-methoxybenzyl)quininium bromide (OSL-14) show potent activity against Plasmodium falciparum.

Quartz OSL Dating of the loess deposit in the eastern Tibetan Plateau and its environment implications since the Last Glaciation

NASA Astrophysics Data System (ADS)

Yang, S.; Cheng, T.; Liu, W.; Fang, X.

2017-12-01

Loess deposit is widespread in the Chuanxi Plateau, the eastern Tibetan Plateau, which is a critical archive for understanding the aeolian process, the evolution of the westerly and the environment changes on the Plateau. Previous studies have shown its aeolian origin, and mainly transported by wind from the western part of the Tibetan Plateau. However, the aeolian processes of the loess and its environment implications are not well understood mainly due to lack of detailed age controls. We carry out a combined quartz optically stimulated luminescence (OSL) dating and accelerator mass spectrometry radiocarbon dating (AMS 14-C) for the loess deposits in Garzê and Jinchuan. The results indicate that the quartz OSL dating can provide reliable age controls for the loess-paleosol sequences from the Chuanxi Plateau, showing the potential of OSL to date loess in the high altitude region. The results indicate that the OSL ages are in agreement with the observed stratigraphy in the field. The constructed OSL and AMS 14-C chronology of the Garzê loess reveals that the widespread loess in Ganzi Region deposited since the Last Glacial. The dust accumulation is rapid during marine isotope stage (MIS) 3 and 2, and a relative low accumulation rate in the Holocene, which may related with the desertification processes of the inner Tibetan Plateau.

Measurements of eye lens doses in interventional cardiology using OSL and electronic dosemeters†.

PubMed

Sanchez, R M; Vano, E; Fernandez, J M; Ginjaume, M; Duch, M A

2014-12-01

The purpose of this paper is to test the appropriateness of OSL and electronic dosemeters to estimate eye lens doses at interventional cardiology environment. Using TLD as reference detectors, personal dose equivalent was measured in phantoms and during clinical procedures. For phantom measurements, OSL dose values resulted in an average difference of -15 % vs. TLD. Tests carried out with other electronic dosemeters revealed differences up to ±20 % versus TLD. With dosemeters positioned outside the goggles and when TLD doses were >20 μSv, the average difference OSL vs. TLD was -9 %. Eye lens doses of almost 700 μSv per procedure were measured in two cases out of a sample of 33 measurements in individual clinical procedures, thus showing the risk of high exposure to the lenses of the eye when protection rules are not followed. The differences found between OSL and TLD are acceptable for the purpose and range of doses measured in the survey. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Reconstruction of settlement phases at Intermediate Bronze Age structures in the Negev Highlands (Israel) using luminescence dating

NASA Astrophysics Data System (ADS)

Junge, Andrea; Lomax, Johanna; Shahack-Gross, Ruth; Dunseth, Zachary C.; Finkelstein, Israel; Fuchs, Markus

2016-04-01

OSL dating is usually applied to sediments in paleoenvironmental sciences. However, there is only limited experience with determining the age of archaeological stone structures by OSL using dust deposits associated with these structures. The age of trapped dust deposits may be used to date the onset of settlement (sediment below structures), settlement activity (occupation layer), or the time after settlement (sediment between collapsed walls and roofs). In this study, OSL dating is applied for establishing a chronology of settlement structures situated in the Negev Highlands, Israel. Two archaeological sites are investigated to identify the occupation history, by dating the aeolian dust trapped within the remains of ancient buildings. OSL dating techniques are applied using coarse grain quartz and a standard SAR protocol. First results indicate that the luminescence properties of the trapped sediments are suitable for OSL dating. Therefore, it was possible to date the onset of sedimentation in a later phase of the human occupation or shortly after the settlement was abandoned, which is supported by archaeological evidence gained from pottery finds and the architecture of the buildings.

In-Situ Dating on Mars: The Potential of OSL Dating

NASA Technical Reports Server (NTRS)

Blair, M. W.; Kalchgruber, R.; Yukihara, E. G.; Bulur, E.; Kim, S. S.; McKeever, W. S.

2004-01-01

More and more evidence is being accumulated that Mars has experienced aeolian, fluvial, and periglacial activity in the (relatively) recent past [1, 2, 3]. However, the temporal scale on which these processes took place is very poorly constrained since crater counting has errors comparable to the age for younger terrains (approx. 1 Ma). Consequently, many researchers have called for methods to establish the climatic and geomorphic history of Mars [4]. Lepper and McKeever [5] suggested developing optically stimulated luminescence (OSL) dating techniques for in-situ dating of martian sediments. Electron paramagnetic resonance (EPR) is closely related to OSL and could easily be incorporated on the same instrument platform [6]. These two methods can aid in developing a geological and climatic history of Mars over the last approx. one million years. Since the initial investigations, work has been carried out to develop OSL instrumentation and dating procedures that are suitable to the unique challenges of the martian environment. In this paper, we highlight the advances made in this project, focusing on OSL dating principles, assumptions, and procedures.

A short-time fading study of Al2O3:C

NASA Astrophysics Data System (ADS)

Nascimento, L. F.; Vanhavere, F.; Silva, E. H.; Deene, Y. De

2015-01-01

This paper studies the short-time fading from Al2O3:C by measuring optically stimulated luminescence (OSL) signals (Total OSL: TOSL, and Peak OSL: POSL) from droplets and Luxel™ pellets. The influence of various bleaching regimes (blue, green and white) and light power is compared. The fading effect is the decay of the OSL signal in the dark at room temperature. Al2O3:C detectors were submitted to various bleaching regimes, irradiated with a reference dose and read out after different time spans. Investigations were carried out using 2 mm size droplet detectors, made of thin Al2O3:C powder mixed with a photocured polymer. Tests were compared to Luxel™-type detectors (Landauer Inc.). Short-time post-irradiation fading is present in OSL results (TOSL and POSL) droplets for time spans up to 200 s. The effect of short-time fading can be lowered/removed when treating the detectors with high-power and/or long time bleaching regimes; this result was observed in both TOSL and POSL from droplets and Luxel™.

Correlation of basic TL, OSL and IRSL properties of ten K-feldspar samples of various origins

NASA Astrophysics Data System (ADS)

Sfampa, I. K.; Polymeris, G. S.; Pagonis, V.; Theodosoglou, E.; Tsirliganis, N. C.; Kitis, G.

2015-09-01

Feldspars stand among the most widely used minerals in dosimetric methods of dating using thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Having very good dosimetric properties, they can in principle contribute to the dating of every site of archaeological and geological interest. The present work studies basic properties of ten naturally occurring K-feldspar samples belonging to three feldspar species, namely sanidine, orthoclase and microcline. The basic properties studied are (a) the influence of blue light and infrared stimulation on the thermoluminescence glow-curves, (b) the growth of OSL, IRSL, residual TL and TL-loss as a function of OSL and IRSL bleaching time and (c) the correlation between the OSL and IRSL signals and the energy levels responsible for the TL glow-curve. All experimental data were fitted using analytical expressions derived from a recently developed tunneling recombination model. The results show that the analytical expressions provide excellent fits to all experimental results, thus verifying the tunneling recombination mechanism in these materials and providing valuable information about the concentrations of luminescence centers.

Replacing the Orchestra? – The Discernibility of Sample Library and Live Orchestra Sounds

PubMed Central

Wolf, Anna; Platz, Friedrich; Mons, Jan

2016-01-01

Recently, musical sounds from pre-recorded orchestra sample libraries (OSL) have become indispensable in music production for the stage or popular charts. Surprisingly, it is unknown whether human listeners can identify sounds as stemming from real orchestras or OSLs. Thus, an internet-based experiment was conducted to investigate whether a classic orchestral work, produced with sounds from a state-of-the-art OSL, could be reliably discerned from a live orchestra recording of the piece. It could be shown that the entire sample of listeners (N = 602) on average identified the correct sound source at 72.5%. This rate slightly exceeded Alan Turing's well-known upper threshold of 70% for a convincing, simulated performance. However, while sound experts tended to correctly identify the sound source, participants with lower listening expertise, who resembled the majority of music consumers, only achieved 68.6%. As non-expert listeners in the experiment were virtually unable to tell the real-life and OSL sounds apart, it is assumed that OSLs will become more common in music production for economic reasons. PMID:27382932

On the use of new generation mobile phone (smart phone) for retrospective accident dosimetry

NASA Astrophysics Data System (ADS)

Lee, J. I.; Chang, I.; Pradhan, A. S.; Kim, J. L.; Kim, B. H.; Chung, K. S.

2015-11-01

Optically stimulated luminescence (OSL) characteristics of resistors, inductors and integrated-circuit (IC) chips, extracted from new generation smart phones, were investigated for the purpose of retrospective accident dosimetry. Inductor samples were found to exhibit OSL sensitivity about 5 times and 40 times higher than that of the resistors and the IC chips, respectively. On post-irradiation storage, the resistors exhibited a much higher OSL fading (about 80 % in 36 h as compared to the value 3 min after irradiation) than IC chips (about 20 % after 36 h) and inductors (about 50 % in 36 h). Higher OSL sensitivity, linear dose response (from 8.7 mGy up to 8.9 Gy) and acceptable fading make inductors more attractive for accident dosimetry than widely studied resistors.

Determination of transmission factors for beta radiation using Al 2O 3:C commercial OSL dosimeters

NASA Astrophysics Data System (ADS)

Pinto, T. N. O.; Caldas, L. V. E.

2010-07-01

In recent years, the optically stimulated luminescence (OSL) technique has been used in personal dosimetry, and aluminum oxide (Al 2O 3:C) has become a very useful material for this technique. The objective of this work was the determination of the transmission factors for beta radiation using Al 2O 3:C commercial dosimeters and the OSL method. The obtained results were similar to the transmission factors reported in the beta source calibration certificates.

In Vitro Partial-Body Dose Assessment Using a Radiation Responsive Protein Biomarker

DTIC Science & Technology

2005-01-01

would design and evaluate the dosimetry of the murine in vivo partial-body irradiation set-up. Thermo-luminescent dosimeter (TLD) chips or Optically...Stimulated Luminescent ( OSL ) should be placed near the mice in the plexiglass tubes in order to measure the dose profile to the mice. GAFCHROMIC...TLDs) chips or ( OSLs ) will be placed near the mice in the Plexiglas tubes in order to measure the dose to the mice. TLDs or OSLs will be placed

Photoluminescence and Optically Stimulated Luminescence Studies of LiAlO2 and LiGaO2 Crystals

DTIC Science & Technology

2015-03-26

tests from the past. In terms of personal dosimetry, OSL dosimeters could potentially replace ther- moluminescence dosimeters (TLDs) which are widely...used by individuals conducting research and maintaining nuclear weapons ( OSL dosimeters are a promising alterna- tive to TLDs because they do not...because they contain lithium, unlike Al2O3:C, the most commonly used OSL dosimeter [2]. The large neutron 1 cross section of lithium-6 makes enriched

An Assessment of the Shipboard Training Effectiveness of the Integrated Damage Control Training Technology (IDCTT) Version 3.0

DTIC Science & Technology

1998-03-01

damage control actions in an assigned area of the ship. Reports are received from the On Scene Leader ( OSL ) and Investigators. Simultaneously, the RPL...control location. A phone talker and plotter will perform in unison with their counterparts in DCC. Key members of the repair party, the OSL and...the obligation of the On Scene Leader ( OSL ). This experienced petty officer is tasked with directing the ATL’s actions and informing the RPL of repair

Using new luminescence methods to date the Palaeolithic: the example of Kalambo Falls

NASA Astrophysics Data System (ADS)

Duller, Geoff; Tooth, Stephen; Barham, Larry

2013-04-01

The Palaeolithic site of Kalambo Falls in the north of Zambia was the subject of detailed study by J.D. Clark in the 1950s with 4 excavations being located within 1 km of each other in a basin upstream of the falls. A rich palaeolithic tool record was recovered, but the value of this record was limited by the lack of chronological information available. In 2006, one of the excavation sites was re-investigated (Barham et al., 2009), including examination of the stratigraphic context and collection of samples for luminescence dating. Many of the sediments in the Kalambo basin were deposited by fluvial activity. Dose distributions in the single grain quartz optically stimulated luminescence (OSL) measurements of the youngest sediments are consistent with incomplete bleaching. However, the residual doses obtained are typically less than 10 Gy, and so for older sediments the impact of incomplete bleaching becomes insignificant. The oldest samples are affected by a different problem, namely saturation of the OSL signal, and many grains are saturated. However in all cases some grains give finite equivalent dose values, making it feasible to calculate single grain quartz OSL ages, but it is difficult to assess whether these ages are reliable or not. Thermally transferred OSL (TT-OSL) from quartz is able to date much older samples due to the high saturation dose of this signal (Duller and Wintle, 2012). Comparison of the TT-OSL and OSL demonstrates that the OSL signal yields age underestimates as samples near saturation. Only by using the two luminescence methods is it possible to create an absolute chronology for this key site stretching back over half a million years. This study demonstrates the potential of using these two luminescence signals together for dating Palaeolithic sites throughout Africa and beyond. Barham, L., Duller, G. A. T., Plater, A. J., Tooth, S. and Turner, S. (2009). Recent excavations at Kalambo Falls, Zambia. Antiquity 83(322). Duller, G. A. T. and Wintle, A. G. (2012). The potential of the thermally transferred optically stimulated luminescence signal from quartz for dating sediments. Quaternary Geochronology 7: 6-20.

Surface dose measurements with commonly used detectors: a consistent thickness correction method

PubMed Central

Higgins, Patrick

2015-01-01

The purpose of this study was to review application of a consistent correction method for the solid state detectors, such as thermoluminescent dosimeters (chips (cTLD) and powder (pTLD)), optically stimulated detectors (both closed (OSL) and open (eOSL)), and radiochromic (EBT2) and radiographic (EDR2) films. In addition, to compare measured surface dose using an extrapolation ionization chamber (PTW 30‐360) with other parallel plate chambers RMI‐449 (Attix), Capintec PS‐033, PTW 30‐329 (Markus) and Memorial. Measurements of surface dose for 6 MV photons with parallel plate chambers were used to establish a baseline. cTLD, OSLs, EDR2, and EBT2 measurements were corrected using a method which involved irradiation of three dosimeter stacks, followed by linear extrapolation of individual dosimeter measurements to zero thickness. We determined the magnitude of correction for each detector and compared our results against an alternative correction method based on effective thickness. All uncorrected surface dose measurements exhibited overresponse, compared with the extrapolation chamber data, except for the Attix chamber. The closest match was obtained with the Attix chamber (−0.1%), followed by pTLD (0.5%), Capintec (4.5%), Memorial (7.3%), Markus (10%), cTLD (11.8%), eOSL (12.8%), EBT2 (14%), EDR2 (14.8%), and OSL (26%). Application of published ionization chamber corrections brought all the parallel plate results to within 1% of the extrapolation chamber. The extrapolation method corrected all solid‐state detector results to within 2% of baseline, except the OSLs. Extrapolation of dose using a simple three‐detector stack has been demonstrated to provide thickness corrections for cTLD, eOSLs, EBT2, and EDR2 which can then be used for surface dose measurements. Standard OSLs are not recommended for surface dose measurement. The effective thickness method suffers from the subjectivity inherent in the inclusion of measured percentage depth‐dose curves and is not recommended for these types of measurements. PACS number: 87.56.‐v PMID:26699319

Position requirements for space station personnel and linkages to portable microcomputer performance assessment

NASA Technical Reports Server (NTRS)

Jeanneret, P. R.

1988-01-01

The development and use of a menu of performance tests that can be self-administered on a portable microcomputer are investigated. In order to identify, develop, or otherwise select the relevant human capabilities/attributes to measure and hence include in the performance battery, it is essential that an analysis be conducted of the jobs or functions that will be performed throughout a space shuttle mission. The primary job analysis instrument, the Position Analysis Questionnaire (PAQ), is discussed in detail so the reader will have sufficient background for understanding the application of the instrument to the various work activities included within the scope of the study, and the derivation of the human requirements (abilities/attributes) from the PAQ analyses. The research methodology is described and includes the procedures used for gathering the PAQ data. The results are presented in detail with specific emphasis on identifying critical requirements that can be measured with a portable computerized assessment battery. A discussion of the results is given with implications for future research.

SU-E-CAMPUS-T-05: Preliminary Results On a 2D Dosimetry System Based On the Optically Stimulated Luminescence of Al2O3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, M; Eller, S; Yukihara, E

2014-06-15

Purpose: To develop a precise 2D dose mapping technique based on the optically stimulated luminescence (OSL) from Al{sub 2}O{sub 3} films for medical applications. Methods: A 2D laser scanning reader was developed using fast F{sup +}-center (lifetime of <7 ns) and slow F-center (lifetime of 35 ms) OSL emission from newly developed Al{sub 2}O{sub 3} films (Landauer Inc.). An algorithm was developed to correct images for both material and system properties. Since greater contribution of the F??-center emission in the recorded signal increases the readout efficiency and robustness of image corrections, Al{sub 2}O{sub 3}:C,Mg film samples are being investigated inmore » addition to Al{sub 2}O{sub 3}:C samples. Preliminary investigations include exposure of the films to a 6 MV photon beam at 10 cm depth in solid water phantom with an SSD of 100 cm, using a 10 cm × 10 cm flat field or a 4 cm × 4 cm field with a 60° wedge filter. Kodak EDR2 radiographic film and EBT2 Gafchromic film were also exposed for comparison. Results: The results indicate that the algorithm is able to correct images and calculate 2D dose. For the wedge field irradiation, the calculated dose at the center of the field was 0.9 Gy for Al{sub 2}O{sub 3}:C and 0.87 Gy for Al{sub 2}O{sub 3}:C,Mg, whereas, the delivered dose was 0.95 Gy. A good qualitative agreement of the dose profiles was obtained between the OSL films and EDR2 and EBT2 films. Laboratory tests using a beta source suggest that a large dynamic range (10{sup −2}−10{sup 2} Gy) can be achieved using this technique. Conclusion: A 2D dosimetry system and an in-house image correction algorithm were developed for 2D film dosimetry in medical applications. The system is in the preliminary stage of development, but the data demonstrates the feasibility of this approach. This work was supported by Landauer, Inc.« less

Optically stimulated luminescence of natural NaCl mineral from Dead Sea exposed to gamma radiation.

PubMed

Roman-Lopez, J; Piña López, Y I; Cruz-Zaragoza, E; Marcazzó, J

2018-08-01

In this work, the continuous wave - optically stimulated luminescence (CW-OSL) emissions of natural salt minerals, collected from Dead Sea in summer of 2015, were studied. The CW-OSL dose response of natural salt showed a linear range between 0.5Gy and 10Gy of gamma radiation of 60 Co. Samples exposed at 3Gy exhibited good repeatability with a variation coefficient of 4.6%. The CW-OSL response as function of the preheating temperature (50-250°C) was analyzed. An increase of 15% of the CW-OSL response was observed in NaCl samples during storage period of 336h. The results showed that the natural Dead Sea salt minerals could be applied as natural dosimeter of gamma radiation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Synthesis and TL/OSL properties of a novel high-sensitive blue-emitting LiSrPO4:Eu2+ phosphor for radiation dosimetry

NASA Astrophysics Data System (ADS)

Palan, C. B.; Koparkar, K. A.; Bajaj, N. S.; Soni, A.; Omanwar, S. K.

2016-07-01

In this study, a series of Eu2+-doped LiSrPO4 phosphors were synthesized via solid-state method. The structural and morphological characterizations were done through X-ray diffraction and scanning electronic microscope. Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically stimulated luminescence (OSL) behaviours of LiSrPO4:Eu2+ phosphors were studied. The LiSrPO4:Eu2+ phosphor shows OSL sensitivity about 8 times than that of α-Al2O3:C phosphor and 6 times than that of LiMgPO4:Tb3+, B phosphor. Moreover, TL sensitivity was about 15 times more as compared to α-Al2O3:C phosphor. The kinetic parameters of TL curve were calculated using peak shape method. In TL/OSL mode, dose-response was almost linear nature, in the range of measurement. The minimum detectable dose was found to be 25.18 μGy with 3 σ of background. Also, reusability was also studies, which shows the phosphor can be reusable for 10 cycles with 0.1 % change in OSL output.

Disposable cartridge biosensor platform for portable diagnostics

NASA Astrophysics Data System (ADS)

Yaras, Yusuf S.; Cakmak, Onur; Gunduz, Ali B.; Saglam, Gokhan; Olcer, Selim; Mostafazadeh, Aref; Baris, Ibrahim; Civitci, Fehmi; Yaralioglu, Goksen G.; Urey, Hakan

2017-03-01

We developed two types of cantilever-based biosensors for portable diagnostics applications. One sensor is based on MEMS cantilever chip mounted in a microfluidic channel and the other sensor is based on a movable optical fiber placed across a microfluidic channel. Both types of sensors were aimed at direct mechanical measurement of coagulation time in a disposable cartridge using plasma or whole blood samples. There are several similarities and also some important differences between the MEMS based and the optical fiber based solutions. The aim of this paper is to provide a comparison between the two solutions and the results. For both types of sensors, actuation of the cantilever or the moving fiber is achieved using an electro coil and the readout is optical. Since both the actuation and sensing are remote, no electrical connections are required for the cartridge. Therefore it is possible to build low cost disposable cartridges. The reader unit for the cartridge contains light sources, photodetectors, the electro coil, a heater, analog electronics, and a microprocessor. The reader unit has different optical interfaces for the cartridges that have MEMS cantilevers and moving fibers. MEMS based platform has better sensitivity but optomechanical alignment is a challenge and measurements with whole blood were not possible due to high scattering of light by the red blood cells. Fiber sensor based platform has relaxed optomechanical tolerances, ease of manufacturing, and it allows measurements in whole blood. Both sensors were tested using control plasma samples for activated-Partial-Thromboplastin-Time (aPTT) measurements. Control plasma test results matched with the manufacturer's datasheet. Optical fiber based system was tested for aPTT tests with human whole blood samples and the proposed platform provided repeatable test results making the system method of choice for portable diagnostics.

SU-E-T-75: Commissioning Optically Stimulated Luminescence Dosimeters for Fast Neutron Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, L; Yang, F; Sandison, G

Purpose: Fast neutrons therapy used at the University of Washington is clinically proven to be more effective than photon therapy in treating salivary gland and other cancers. A nanodot optically stimulated luminescence (OSL) system was chosen to be commissioned for patient in vivo dosimetry for neutron therapy. The OSL-based radiation detectors are not susceptible to radiation damage caused by neutrons compared to diodes or MOSFET systems. Methods: An In-Light microStar OSL system was commissioned for in vivo use by radiating Landauer nanodots with neutrons generated from 50.0 MeV protons accelerated onto a beryllium target. The OSLs were calibrated the depthmore » of maximum dose in solid water localized to 150 cm SAD isocenter in a 10.3 cm square field. Linearity was tested over a typical clinical dose fractionation range i.e. 0 to 150 neutron-cGy. Correction factors for transient signal fading, trap depletion, gantry angle, field size, and wedge factor dependencies were also evaluated. The OSLs were photo-bleached between radiations using a tungsten-halogen lamp. Results: Landauer sensitivity factors published for each nanodot are valid for measuring photon and electron doses but do not apply for neutron irradiation. Individually calculated nanodot calibration factors exhibited a 2–5% improvement over calibration factors computed by the microStar InLight software. Transient fading effects had a significant impact on neutron dose reading accuracy compared to photon and electron in vivo dosimetry. Greater accuracy can be achieved by calibrating and reading each dosimeter within 1–2 hours after irradiation. No additional OSL correction factors were needed for field size, gantry angle, or wedge factors in solid water phantom measurements. Conclusion: OSL detectors are a useful for neutron beam in vivo dosimetry verification. Dosimetric accuracy comparable to conventional diode systems can be achieved. Accounting for transient fading effects during the neutron beam calibration is a critical component for achieving comparable accuracy.« less

Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Buhao; Xu, Xuhui; Li, Qianyue

Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R{sup 3+} ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}. The greatly improved LPL performance was observed in Nd{sup 3+} co-doped samples, which indicates that the incorporation of Nd{sup 3+} creates suitable traps for LPL. While co-doping Tm{sup 3+} ions, the intensity of high temperature of thermoluminescence band in CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors is enhanced for the formation of the most suitable trapsmore » which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R{sup 3+} ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} exhibits different read-in/read-out performance as well. - Graphical abstract: OSL emission spectra of Ca{sub 0.995}Al{sub 2}O{sub 4}:0.0025Eu{sup 2+}, 0.0025R{sup 3+} (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100 s). Inset: Blue emission pictures under varying stimulation time. - Highlights: • The LPL and OSL properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} were investigated. • An alternative approach to control the trap depth of CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor was proposed. • A new oxide ETM phosphor exhibiting intense and stable OSL was explored.« less

Validations of a portable home sleep study with twelve-lead polysomnography: comparisons and insights into a variable gold standard.

PubMed

Michaelson, Peter G; Allan, Patrick; Chaney, John; Mair, Eric A

2006-11-01

Accurate and timely diagnosis for patients with obstructive sleep apnea (OSA) is imperative. Unfortunately, growing interest in this diagnosis has resulted in increased requests and waiting times for polysomnography (PSG), as well as a potential delay in diagnosis and treatment. This study evaluated the accuracy and viability of utilizing SNAP (SNAP Laboratories, LLC, Wheeling, Illinois), a portable home sleep test, as an alternative to traditional PSG in diagnosing OSA. This prospective clinical trial included 59 patients evaluated at our institution's sleep laboratory. Concurrent PSG and SNAP testing was performed for 1 night on each patient. Independent, blinded readers at our institution and at an outside-accredited institution read the PSG data, and 2 independent, blinded readers interpreted the SNAP data at SNAP laboratories. The apnea-hypopnea index (AHI) was used to compare the 2 testing modalities. The correlation coefficient, receiver operating characteristic curve analysis, and the Bland-Altman curves, as well as sensitivity, specificity, inter-reader variability, positive predictive value, and negative predictive value, were used to compare SNAP and PSG. There is a definitive, statistically sound correlation between the AHIs determined from both PSG and SNAP. This relationship holds true for all measures of comparison, while displaying a concerning, weaker correlation between the different PSG interpretations. There is a convincing correlation between the study-determined AHIs of both PSG and SNAP. This finding supports SNAP as a suitable alternative to PSG in identifying OSA, while accentuating the inherent variation present in a PSG-derived AHI. This test expands the diagnostic and therapeutic prowess of the practicing otolaryngologist by offering an alternative OSA testing modality that is associated with not only less expense, decreased waiting time, and increased convenience, but also statistically proven accuracy.

Dosimetry of Al2O3 optically stimulated luminescent dosimeter at high energy photons and electrons

NASA Astrophysics Data System (ADS)

Yusof, M. F. Mohd; Joohari, N. A.; Abdullah, R.; Shukor, N. S. Abd; Kadir, A. B. Abd; Isa, N. Mohd

2018-01-01

The linearity of Al2O3 OSL dosimeters (OSLD) were evaluated for dosimetry works in clinical photons and electrons. The measurements were made at a reference depth of Zref according to IAEA TRS 398:2000 codes of practice at 6 and 10 MV photons and 6 and 9 MeV electrons. The measured dose was compared to the thermoluminescence dosimeters (TLD) and ionization chamber commonly used for dosimetry works for higher energy photons and electrons. The results showed that the measured dose in OSL dosimeters were in good agreement with the reported by the ionization chamber in both high energy photons and electrons. A reproducibility test also reported excellent consistency of readings with the OSL at similar energy levels. The overall results confirmed the suitability of OSL dosimeters for dosimetry works involving high energy photons and electrons in radiotherapy.

A laser based frequency modulated NL-OSL phenomenon

NASA Astrophysics Data System (ADS)

Mishra, D. R.; Bishnoi, A. S.; Soni, Anuj; Rawat, N. S.; Bhatt, B. C.; Kulkarni, M. S.; Babu, D. A. R.

2015-01-01

The detailed theoretical and experimental approach to novel technique of pulse frequency modulated stimulation (PFMS) method has been described for NL-OSL phenomenon. This method involved pulsed frequency modulation with respect to time for fixed pulse width of 532 nm continuous wave (CW)-laser light. The linearly modulated (LM)-, non-linearly (NL)-stimulation profiles have been generated using fast electromagnetic optical shutter. The PFMS parameters have been determined for present experimental setup. The PFMS based LM-, NL-OSL studies have been carried out on dosimetry grade single crystal α-Al2O3:C. The photo ionization cross section of α-Al2O3:C has been found to be ∼9.97 × 10-19 cm2 for 532 nm laser light using PFMS LM-OSL studies under assumption of first order of kinetic. This method of PFMS is found to be a potential alternative to generate different stimulation profiles using CW-light sources.

Leaving the structural ivory tower, assisted by interactive 3D PDF.

PubMed

Kumar, Pravin; Ziegler, Alexander; Grahn, Alexander; Hee, Chee Seng; Ziegler, Andreas

2010-08-01

The ability to embed interactive three-dimensional (3D) models into electronic publications in portable document format (PDF) greatly enhances the accessibility of molecular structures. Here, we report advances in this procedure and discuss what is needed to develop this format into a truly useful tool for the structural biology community as well as for readers who are less well trained in molecular visualization. Copyright 2010 Elsevier Ltd. All rights reserved.

Mobile Learning Panel (Briefing Slides)

DTIC Science & Technology

2010-08-12

00-2010 4 . TITLE AND SUBTITLE Mobile Learning Panel 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT...the Air Force and draw information from an enterprise knowledge base. • Self-paced individual training • Mandatory annual training • Classroom...iPhone • Sony Playstation Portable • Sony e-Reader • HTC, Palm, and Android CONTACT Leeescoemobile@conus.army.mil EVENT FACEBOOK Fort Lee

Development of OSL system using two high-density blue LEDs equipped with liquid light guides

NASA Astrophysics Data System (ADS)

Choi, J. H.; Kim, M. J.; Cheong, C. S.; Hong, D. G.

2014-03-01

In recent years, considerable developments in optically stimulated luminescence (OSL) have been made in the fields of radiation dosimetry, age determination, and medical applications. A compact and economical OSL system comprising a precision x-y-z stage for loading 12 samples, a small X-ray generator for radiation dosing, and two powerful blue light emitting diodes (LEDs) for optical stimulation equipped with VIS liquid light guides (VIS-LLGs) has been developed. This paper describes the principal features of the system along with the examples of measurements performed by the system.

Optically Stimulated Luminescence (OSL) of Tooth Enamel and its Potential Use in Post-Radiation Exposure Triage

PubMed Central

DeWitt, R.; Klein, D. M.; Yukihara, E. G.; Simon, S. L.; McKeever, S. W. S.

2009-01-01

Optically stimulated luminescence (OSL) properties of dental enamel are discussed with a view to the development of an in-vivo dose assessment technique for medical triage following a radiological/nuclear accident or terrorist event. In the OSL technique, past radiation exposure is assessed by stimulating the sample with light of one wavelength and monitoring the luminescence at another wavelength under the assumption that the luminescence originates from the recombination of radiation-induced charges trapped at metastable defects in the enamel and that the intensity of the luminescence signal is in proportion to the absorbed radiation dose. Several primary findings emerged from this research: (a) sensitivities varied considerably between different teeth and also between fragments of the same tooth, (b) OSL signals were found to decay rapidly during the first 12 hours after irradiation and slower afterwards, (c) the fading rate of the luminescence signal varied between fragments, (d) blue light stimulation yields greater sensitivity than infra-red stimulation, while the OSL signal obtained with a high-intensity pulsed green-light laser was found to be not correlated with the radiation dose. Significant challenges remain to developing a practical in-vivo technique including the development of calibration procedures and lowering minimum detectable doses. PMID:20065717

Optically stimulated luminescence (OSL) of carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for film dosimetry in radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schembri, V.; Heijmen, B. J. M.

2007-06-15

Introduction and Purpose: Conventional x-ray films and radiochromic films have inherent challenges for high precision radiotherapy dosimetry. Here we have investigated basic characteristics of optically stimulated luminescence (OSL) of irradiated films containing carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for dosimetry in therapeutic photon and electron beams. Materials and Methods: The OSL films consist of a polystyrene sheet, with a top layer of a mixture of single crystals of Al{sub 2}O{sub 3}:C, ground into a powder, and a polyester base. The total thickness of the films is 0.3 mm. Measurements have been performed in a water equivalent phantom, using 4, 6,more » 10, and 18 MV photon beams, and 6-22 MeV electron beams. The studies include assessment of the film response (acquired OSL signal/delivered dose) on delivered dose (linearity), dose rate (1-6 Gy/min), beam quality, field size and depth (6 MV, ranges 4x4-30x30 cm{sup 2}, d{sub max}-35 cm). Doses have been derived from ionization chamber measurements. OSL films have also been compared with conventional x-ray and GafChromic films for dosimetry outside the high dose area, with a high proportion of low dose scattered photons. In total, 787 OSL films have been irradiated. Results: Overall, the OSL response for electron beams was 3.6% lower than for photon beams. Differences between the various electron beam energies were not significant. The 6 and 18 MV photon beams differed in response by 4%. No response dependencies on dose rate were observed. For the 6 MV beam, the field size and depth dependencies of the OSL response were within {+-}2.5%. The observed inter-film response variation for films irradiated with the same dose varied from 1% to 3.2% (1 SD), depending on the measurement day. At a depth of 20 cm, 5 cm outside the 20x20 cm{sup 2} 6 and 18 MV beams, an over response of 17% was observed. In contrast to GafChromic and conventional x-ray films, the response of the Al{sub 2}O{sub 3}:C films is linear in the clinically relevant dose range 0-200 cGy. Conclusions: Measurement of the OSL signal of irradiated films containing Al{sub 2}O{sub 3}:C is a promising technique for film dosimetry in radiotherapy with no or small response variations with dose rate, beam quality, field size and depth, and a linear response from 0 to 200 cGy.« less

Estimation of identification limit for a small-type OSL dosimeter on the medical images by measurement of X-ray spectra.

PubMed

Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

2016-07-01

Our aim in this study is to derive an identification limit on a dosimeter for not disturbing a medical image when patients wear a small-type optically stimulated luminescence (OSL) dosimeter on their bodies during X-ray diagnostic imaging. For evaluation of the detection limit based on an analysis of X-ray spectra, we propose a new quantitative identification method. We performed experiments for which we used diagnostic X-ray equipment, a soft-tissue-equivalent phantom (1-20 cm), and a CdTe X-ray spectrometer assuming one pixel of the X-ray imaging detector. Then, with the following two experimental settings, corresponding X-ray spectra were measured with 40-120 kVp and 0.5-1000 mAs at a source-to-detector distance of 100 cm: (1) X-rays penetrating a soft-tissue-equivalent phantom with the OSL dosimeter attached directly on the phantom, and (2) X-rays penetrating only the soft-tissue-equivalent phantom. Next, the energy fluence and errors in the fluence were calculated from the spectra. When the energy fluence with errors concerning these two experimental conditions was estimated to be indistinctive, we defined the condition as the OSL dosimeter not being identified on the X-ray image. Based on our analysis, we determined the identification limit of the dosimeter. We then compared our results with those for the general irradiation conditions used in clinics. We found that the OSL dosimeter could not be identified under the irradiation conditions of abdominal and chest radiography, namely, one can apply the OSL dosimeter to measurement of the exposure dose in the irradiation field of X-rays without disturbing medical images.

TL and OSL characterization of Eu3+ doped Y2O3: Application in dosimetry

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Coetsee, E.; Swart, H. C.

2018-05-01

Thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of beta irradiated Eu3+ doped Y2O3 nanophosphor have been investigated in this paper. The Eu3+ doped Y2O3 nanophosphor was synthesized by solution combustion technique and synthesized material was annealed at 900°C. The annealed materials were exposed to β-ray for various dose. TL glow with prominent peak at 403 K and weak glow peak at 660 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 8.125 - 40.625 Gy. The TL kinetic parameters were calculated using glow curve deconvoluted (GCD) and peak shape methods. The TL glows exhibits general order kinetics. Intense continuous wave optical stimulated luminescence (CW-OSL) was observed in the sample. These material exhibits linearity at low dose, good reproducibility and response of intense OSL and hence, these results suggests that this material may be suitable for dosimetry applications.

Single photon detection and signal analysis for high sensitivity dosimetry based on optically stimulated luminescence with beryllium oxide

NASA Astrophysics Data System (ADS)

Radtke, J.; Sponner, J.; Jakobi, C.; Schneider, J.; Sommer, M.; Teichmann, T.; Ullrich, W.; Henniger, J.; Kormoll, T.

2018-01-01

Single photon detection applied to optically stimulated luminescence (OSL) dosimetry is a promising approach due to the low level of luminescence light and the known statistical behavior of single photon events. Time resolved detection allows to apply a variety of different and independent data analysis methods. Furthermore, using amplitude modulated stimulation impresses time- and frequency information into the OSL light and therefore allows for additional means of analysis. Considering the impressed frequency information, data analysis by using Fourier transform algorithms or other digital filters can be used for separating the OSL signal from unwanted light or events generated by other phenomena. This potentially lowers the detection limits of low dose measurements and might improve the reproducibility and stability of obtained data. In this work, an OSL system based on a single photon detector, a fast and accurate stimulation unit and an FPGA is presented. Different analysis algorithms which are applied to the single photon data are discussed.

Investing the temporal and spatial scale variations of luminescence sensitivity of loess in the Chinese Loess Plateau since the last interglacial

NASA Astrophysics Data System (ADS)

Lv, T.; Sun, J.; Gong, Z.

2017-12-01

The provenance of the eolian deposits on the Loess Plateau has long been one of the most important issues. Although the luminescence sensitivity of the quartz grains of desert sands has been used in tracing provenance, and the vertical variation of OSL sensitivity of Loess in the central Chinese Loess plateau (CLP) has been studied, it still remains uncertain about the temporal and spatial scale variations of luminescence sensitivity of loess. This paper chose the eolian deposits of Shimao (SM) section in the northern margin of the Chinese Loess Plateau and of Luochuan (LC) section in the central Chinese Loess Plateau. Firstly, the temporal scale variations of luminescence sensitivity of different quartz grians (38-64 and 64-90μm) from sand/loess of SM section have been studied respectively. Our results indicate that they both have similar trend in the strength of luminescence sensitivity, characterized by lower values in sand/loess beds and higher values in soils. The OSL sensitivity of quartz grains of the sand-loess-soil sequence shows very similar trend to the magnetic susceptibility fluctuations. Secondly, the spatial scale variations of luminescence sensitivity of loess in the Chinese Loess Plateau since the last interglacial were studied by comparing the values of SM section and LC section. The OSL sensitivity of quartz grains from the two sections since the last interglacial change synchronously. However, the OSL sensitivity values of quartz grains from the same loess/paleosol beds of LC section are higher than these values of SM section. We suggest that the temporal variation of OSL sensitivity of SM is main influenced by the retreat-advance of deserts. The spatial variation of OSL sensitivity mainly is due to the different sedimentary history, containing of repeated erosion, transport and deposition cycles which controlled by cyclic climatic change. The higher OSL sensitivity values of quartz grains in LC section relates of longer transport distance and of more sedimentary history than these values in SM section. Keywords: Luminescence sensitivity; Quartz; provenance; Loess Plateau

An application of artificial neural intelligence for personal dose assessment using a multi-area OSL dosimetry system.

PubMed

Lee, S Y; Kim, B H; Lee, K J

2001-06-01

Significant advances have been made in recent years to improve measurement technology and performance of phosphor materials in the fields of optically stimulated luminescence (OSL) dosimetry. Pulsed and continuous wave OSL studies recently carried out on alpha-Al2O3:C have shown that the material seems to be the most promising for routine application of OSL for dosimetric purposes. The main objective of the study is to propose a new personal dosimetry system using alpha-Al2O3:C by taking advantage of its optical properties and energy dependencies. In the process of the study, a new dose assessment algorithm was developed using artificial neural networks in hopes of achieving a higher degree of accuracy and precision in personal OSL dosimetry system. The original hypothesis of this work is that the spectral information of X- and gamma-ray fields may be obtained by the analysis of the response of a multi-element system. In this study, a feedforward neural network using the error back-propagation method with Bayesian optimization was applied for the response unfolding procedure. The validation of the proposed algorithm was investigated by unfolding the 10 measured responses of alpha-Al2O3:C for arbitrarily mixed photon fields which range from 20 to 662 keV. c2001 Elsevier Science Ltd. All rights reserved.

Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C.

PubMed

Yukihara, E G; Gaza, R; McKeever, S W S; Soares, C G

2004-02-01

The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. c2003 Elsevier Ltd. All rights reserved.

Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C

NASA Technical Reports Server (NTRS)

Yukihara, E. G.; Gaza, R.; McKeever, S. W. S.; Soares, C. G.

2004-01-01

The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. c2003 Elsevier Ltd. All rights reserved.

Collective odor source estimation and search in time-variant airflow environments using mobile robots.

PubMed

Meng, Qing-Hao; Yang, Wei-Xing; Wang, Yang; Zeng, Ming

2011-01-01

This paper addresses the collective odor source localization (OSL) problem in a time-varying airflow environment using mobile robots. A novel OSL methodology which combines odor-source probability estimation and multiple robots' search is proposed. The estimation phase consists of two steps: firstly, the separate probability-distribution map of odor source is estimated via Bayesian rules and fuzzy inference based on a single robot's detection events; secondly, the separate maps estimated by different robots at different times are fused into a combined map by way of distance based superposition. The multi-robot search behaviors are coordinated via a particle swarm optimization algorithm, where the estimated odor-source probability distribution is used to express the fitness functions. In the process of OSL, the estimation phase provides the prior knowledge for the searching while the searching verifies the estimation results, and both phases are implemented iteratively. The results of simulations for large-scale advection-diffusion plume environments and experiments using real robots in an indoor airflow environment validate the feasibility and robustness of the proposed OSL method.

Collective Odor Source Estimation and Search in Time-Variant Airflow Environments Using Mobile Robots

PubMed Central

Meng, Qing-Hao; Yang, Wei-Xing; Wang, Yang; Zeng, Ming

2011-01-01

This paper addresses the collective odor source localization (OSL) problem in a time-varying airflow environment using mobile robots. A novel OSL methodology which combines odor-source probability estimation and multiple robots’ search is proposed. The estimation phase consists of two steps: firstly, the separate probability-distribution map of odor source is estimated via Bayesian rules and fuzzy inference based on a single robot’s detection events; secondly, the separate maps estimated by different robots at different times are fused into a combined map by way of distance based superposition. The multi-robot search behaviors are coordinated via a particle swarm optimization algorithm, where the estimated odor-source probability distribution is used to express the fitness functions. In the process of OSL, the estimation phase provides the prior knowledge for the searching while the searching verifies the estimation results, and both phases are implemented iteratively. The results of simulations for large-scale advection–diffusion plume environments and experiments using real robots in an indoor airflow environment validate the feasibility and robustness of the proposed OSL method. PMID:22346650

Late Quaternary stratigraphy and luminescence geochronology of the northeastern Mojave Desert

USGS Publications Warehouse

Mahan, S.A.; Miller, D.M.; Menges, C.M.; Yount, J.C.

2007-01-01

The chronology of the Holocene and late Pleistocene deposits of the northeastern Mojave Desert have been largely obtained using radiocarbon ages. Our study refines and extends this framework using optically stimulated luminescence (OSL) to date deposits from Valjean Valley, Silurian Lake Playa, Red Pass, and California Valley. Of particular interest are eolian fine silts incorporated in ground-water discharge (GWD) deposits bracketed at 185-140 and 20-50 ka. Alluvial fan deposits proved amenable for OSL by dating both eolian sand lenses and reworked eolian sand in a matrix of gravel that occurs within the fan stratigraphy. Lacustrine sand in spits and bars also yielded acceptable OSL ages. These OSL ages fill gaps in the geochronology of desert deposits, which can provide data relevant to understanding the responses of several depositional systems to regional changes in climate. This study identifies the most promising deposits for future luminescence dating and suggests that for several regions of the Mojave Desert, sediments from previously undated landforms can be more accurately placed within correct geologic map units.

Multichannel Dosimeter and α-Al2O3:C Optically Stimulated Luminescence (OSL) Fiber Sensors for Use in Radiation Therapy—Evaluation With Photon Beams

NASA Astrophysics Data System (ADS)

Magne, Sylvian; de Carlan, Loïc; Bordy, Jean-Marc; Isambert, Aurélie; Bridier, André; Ferdinand, Pierre

2011-04-01

A multichannel OSL fiber optic dosimeter based on optically stimulated luminescence (OSL) of alumina is proposed for online in vivo dosimetry (IVD) in radiation therapy (RT). Two types of dosimetric-grade Al2O3:C crystals are compared and show different behavior according to manufacturing process. Metrological validations have been performed with a Saturne 43 LINAC in reference conditions at CEA LIST LNHB (French Ionizing Radiation Reference Laboratory). The dose response of OSL integrals under photon beam irradiation (6, 12, and 20 MV) show sublinearity behavior modeled by second-order equations and exhibit a small energy dependence (between 0.7% and 1.4%), explained by a modified intermediate cavity model adapted to a LINAC photon spectrum. Preclinical tests at Institut Gustave Roussy (IGR) prove that a proper design for a PMMA build-up cap leads to a low dependence vs photon beam orientation (± 1.5% and ± 0.9%) and vs field size in view of surface measurements.

Late Cenozoic Deformation in the Western Tarim Basin, NW China

NASA Astrophysics Data System (ADS)

Thompson, J. A.; Burbank, D. W.; Chen, J.; Li, T.

2009-12-01

The Tian Shan in NW China is one of the most active regions of intracontinental deformation in the world, accommodating a large fraction (~40%) of the shortening from the Indo-Eurasian collision. The western Tarim Basin, situated between the southern Tian Shan and Pamir Mountains, manifests this deformation through a series of east-west trending fault-related folds that have formed during the late Cenozoic. Previous studies in this region have focused on the kinematics, style, and timing of detachment folds related to folding within the foreland basin of the southern Tian Shan. In contrast, this study focuses on the deformation caused by fault-propagation folding resulting from the northward movement of the Pamir. The rates of deformation are calculated using a combination of optically stimulated luminescence (OSL) ages, structural mapping and differential GPS surveys of fault scarps and deformed terrace surfaces crossing active folds. OSL dating provides the time since the sediment was last exposed to daylight, i.e., time since burial. Consequently, OSL is useful for dating the abandonment of terrace surfaces due to tectonic (fold growth) or climatic events. OSL quartz samples were collected from silt lenses within gravel topping the terraces. Most of the quartz OSL signals are weak, thus several grain sizes (silt (4-11 µm, 8-15 µm) and sand (90-125 µm)) were analyzed and different integrations of the shine-down curves were explored to calculate equivalent doses. The implications for different equivalent doses and ages on the calculation of rates of deformation are also addressed.

[BeO-OSL detectors for dose measurements in cell cultures].

PubMed

Andreeff, M; Sommer, D; Freudenberg, R; Reichelt, U; Henniger, J; Kotzerke, J

2009-01-01

The absorbed dose is an important parameter in experiments involving irradiation of cells in vitro with unsealed radionuclides. Typically, this is estimated with a model calculation, although the results thus obtained cannot be verified. Generally used real-time measurement methods are not applicable in this setting. A new detector material with in vitro suitability is the subject of this work. Optically-stimulated luminescence (OSL) dosimeters based on beryllium oxide (BeO) were used for dose measurement in cell cultures exposed to unsealed radionuclides. Their qualitative properties (e. g. energy-dependent count rate sensitivity, fading, contamination by radioactive liquids) were determined and compared to the results of a Monte Carlo simulation (using AMOS software). OSL dosimeters were tested in common cell culture setups with a known geometry. Dose reproducibility of the OSL dosimeters was +/-1.5%. Fading at room temperature was 0.07% per day. Dose loss (optically-stimulated deletion) under ambient lighting conditions was 0.5% per minute. The Monte Carlo simulation for the relative sensitivity at different beta energies provided corresponding results to those obtained with the OSL dosimeters. Dose profile measurements using a 6 well plate and 14 ml PP tube showed that the geometry of the cell culture vessel has a marked influence on dose distribution with 188Re. A new dosimeter system was calibrated with beta-emitters of different energy. It turned out as suitable for measuring dose in liquids. The dose profile measurements obtained are suitably precise to be used as a check against theoretical dose calculations.

Temperature-dependent OSL properties of nano-phosphors LiAlO2:C and α-Al2O3:C

NASA Astrophysics Data System (ADS)

Agarwal, Mini; Garg, Sandeep K.; Asokan, K.; Kumar, Pratik

2018-06-01

The present study focuses on the synthesis and characterization of carbon doped nano-phosphors, LiAlO2 and α-Al2O3 and their temperature-dependent optically stimulated luminescence (TA-OSL) characteristics in the temperature ranges of 25-350 °C. These nano-phosphors with the carbon concentration of 0.01 mol% exhibits high luminescent intensity for LiAlO2:C in the low dose range of 1 mGy-7 Gy and for α-Al2O3:C in the range of 100 mGy-1 kGy. Both these nano-phosphors are of polycrystalline in nature, having grain size 15-50 nm as confirmed by the X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM), respectively. The maximum TA-OSL intensities are observed at 125 °C for LiAlO2:C and 200 °C for Al2O3:C, and reveal the presence of deep defect centres. The Arrhenius analysis shows the activation energies Ea = 0.06 ± 0.02 eV for LiAlO2:C and Ea = 0.04 ± 0.01 eV, & Eb = 0.48 ± 0.07 eV for Al2O3:C. The TA-OSL and OSL characteristics are discussed with special reference to the medical and high radiation dosimetry. These compounds, LiAlO2:C and α-Al2O3:C, are non-toxic, robust and are potential candidates for reusable dosimetry.

OSL surface exposure dating of wave-emplaced coastal boulders - Research concept and first results from the Rabat coast, Morocco

NASA Astrophysics Data System (ADS)

Brill, Dominik; May, Simon Matthias; Mhammdi, Nadia; King, Georgina; Brückner, Helmut

2017-04-01

Fields of wave-emplaced blocks and boulders represent impressive evidence of cyclone and tsunami flooding over Holocene time scales. Unfortunately, their use for coastal hazard assessment is in many cases impeded by the absence of appropriate dating approaches, which are needed to generate robust chronologies. The commonly applied AMS-14C, U/Th or ESR dating of coral-reef rocks and marine organisms attached to the clasts depends on a - mostly hypothetical - coincidence between the organisms' death and boulder displacement, and inferred event chronologies may be biased by the marine 14C-reservoir effect and reworked organisms. Here we discuss the potential of the recently developed optically stimulated luminescence (OSL) surface exposure dating technique to directly date the relocation process of wave-emplaced boulders. By measuring the depth-dependent resetting of luminescence signals in exposed rock surfaces and comparing it to the signal-depth profiles of known-age samples, OSL surface exposure dating may be capable to model direct depositional ages for boulder transport. Thereby, it promises to overcome the limitations of existing dating techniques, and to decipher complex transport histories of clasts that underwent multiple phases of exposure and burial. The concept and some first results of OSL surface exposure dating shall be presented for coastal boulders from the Rabat coast, Morocco, where the preconditions for successful dating are promising: (i) Several coastal boulders show clear indication of overturning during wave transport in the form of downward-facing bio-eroded surfaces; (ii) the boulders are composed of different types of sandstone that contain quartz and feldspar, the required dosimeters for OSL dating; (iii) all boulders are of Holocene age and, therefore, in the dating range of OSL surface exposure dating. The main challenges for a successful application are the intensive bio-erosion and weathering of some surfaces exposed after transport, and the need for method calibration using surfaces with similar lithology and known exposure ages. However, in the best case, OSL surface exposure dating will provide quantitative information about the frequency-magnitude relationship of extreme wave events at the Rabat coast, in particular determining whether severe tsunami-induced flooding can be expected (e.g. during the 1755 Lisbon tsunami and similar events), or if boulders were only moved during flooding by exceptional winter storms.

SU-F-T-327: Total Body Irradiation In-Vivo Dose Measurements Using Optically Stimulated Luminescence (OSL) NanoDots and Farmer Type Ion Chamber

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kaur, H; Kumar, S; Sarkar, B

Purpose: This study was performed to analyze the agreement between optically stimulated luminescence (OSL) nanoDots measured doses and 0.6 cc Farmer type ionization chamber measured doses during total body irradiation (TBI). Methods: In-vivo dose measurements using OSL nanoDots and Farmer chamber were done in a total of twelve patients who received TBI at our center by bilateral parallel-opposed beams technique. In this technique, the patient is kept inside the TBI box which is filled with rice bags and irradiated using two bilateral parallel opposed beams of 40×40 cm{sup 2} size with 45° collimator rotation at an SSD of 333.5 cmmore » in an Elekta Synergy linear accelerator. All patients received a dose of 2 Gy in single fraction as conditioning regimen. The beams were equally weighted at the midplane of the box. The nanoDots were placed over forehead, right and left neck, right and left lung, umbilicus, right and left abdomen, medial part of thigh, knee and toe. A 0.6 cc Farmer chamber was placed in between the thighs of the patient. Measured doses are reported along with the statistical comparisons using paired sample t-test. Results: For the above sites the mean doses were 212.2±21.1, 218.2±7.6, 218.7±9.3, 215.6±9.5, 217.5±11.5, 214.5±7.7, 218.3±6.8, 221.5±15, 229.1±11.0, 220.5±7.7 and 223.3±5.1 cGy respectively. For all OSL measurements the mean dose was 218.6±11.8 cGy. Farmer chamber measurements yielded a mean dose of 208.8±15.6 cGy. Statistical analysis revealed that there was no significant difference between OSL measured doses in forehead, right and left neck, right and left lung, umbilicus, right and left abdomen and toe and Farmer chamber measured doses (0.72≤p≤0.06). However the mean OSL doses at thigh and knee were statistically different (p<0.05) from the Farmer chamber measurements. Conclusion: OSL measurements were found to be in agreement with Farmer type ionization chamber measurements in in-vivo dosimetry of TBI.« less

Verifying the new luminescence surface-exposure dating technique--rock falls in Canyonlands National Park, Utah

NASA Astrophysics Data System (ADS)

Pederson, J. L.; Sohbati, R.; Murray, A. S.; Jain, M.

2015-12-01

Recent studies have helped develop the optically stimulated luminescence (OSL) dating of rock surfaces, as applied to the age of the famous Great Gallery rock art panel in Canyonlands National Park. Chapot et al. (2012) dated a key rock fall to ~900 yrs ago by applying OSL to the outer 1-mm buried surface of a sandstone talus boulder, an age confirmed by independent radiocarbon dating. Later, in a novel approach and with the use of a local known-age calibration sample, Sohbati et al. (2012) modelled the millimeter-scale OSL-depth profile to determine a pre-burial exposure duration of ~700 years for the same rock fall. This combination of rock-fall dating and exposure dating--an approach with broad potential to date Holocene mass movements--constrains the creation of the Great Gallery rock art to a time window of 900 to ~1600 years ago (Pederson et al., 2014), a result met with some controversy. Here we report on a new phase of research to verify these results and further refine OSL-profile exposure dating for mass movements. New analyses from within and near the Great Gallery alcove include: i) exposure dating of the same alcove surface upon which the rock art is painted with a predicted exposure age of ~1600 years; ii) exposure dating of the top (light-exposed) side of the same rock-fall boulder whose buried side was previously dated to test for reproduction of the known age; and iii) an improved calibration sample from a nearby trail/road-cut for verification. The residual OSL signal is measured with depth in millimeter-thick increments of all samples. We first determine the site-specific luminescence reduction rate at the rock surface by fitting the OSL surface-exposure dating model to the calibration profile from the trail/road-cut. This parameterized model then provides exposure ages for the bleaching profiles observed in the other samples. Results have implications for the application of OSL rock-surface and exposure-profile dating in other settings where quartz-rich rock is available. We discuss how the light-exposed top and buried underside of clasts can be used in tandem for calibration. The technique has particular relevance to younger timescales over which cosmogenic nuclides are of limited application.

Three-dimensional portable document format: a simple way to present 3-dimensional data in an electronic publication.

PubMed

Danz, Jan C; Katsaros, Christos

2011-08-01

Three-dimensional (3D) models of teeth and soft and hard tissues are tessellated surfaces used for diagnosis, treatment planning, appliance fabrication, outcome evaluation, and research. In scientific publications or communications with colleagues, these 3D data are often reduced to 2-dimensional pictures or need special software for visualization. The portable document format (PDF) offers a simple way to interactively display 3D surface data without additional software other than a recent version of Adobe Reader (Adobe, San Jose, Calif). The purposes of this article were to give an example of how 3D data and their analyses can be interactively displayed in 3 dimensions in electronic publications, and to show how they can be exported from any software for diagnostic reports and communications among colleagues. Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Desktop document delivery using portable document format (PDF) files and the Web.

PubMed Central

Shipman, J P; Gembala, W L; Reeder, J M; Zick, B A; Rainwater, M J

1998-01-01

Desktop access to electronic full-text literature was rated one of the most desirable services in a client survey conducted by the University of Washington Libraries. The University of Washington Health Sciences Libraries (UW HSL) conducted a ten-month pilot test from August 1996 to May 1997 to determine the feasibility of delivering electronic journal articles via the Internet to remote faculty. Articles were scanned into Adobe Acrobat Portable Document Format (PDF) files and delivered to individuals using Multipurpose Internet Mail Extensions (MIME) standard e-mail attachments and the Web. Participants retrieved scanned articles and used the Adobe Acrobat Reader software to view and print files. The pilot test required a special programming effort to automate the client notification and file deletion processes. Test participants were satisfied with the pilot test despite some technical difficulties. Desktop delivery is now offered as a routine delivery method from the UW HSL. PMID:9681165

Desktop document delivery using portable document format (PDF) files and the Web.

PubMed

Shipman, J P; Gembala, W L; Reeder, J M; Zick, B A; Rainwater, M J

1998-07-01

Desktop access to electronic full-text literature was rated one of the most desirable services in a client survey conducted by the University of Washington Libraries. The University of Washington Health Sciences Libraries (UW HSL) conducted a ten-month pilot test from August 1996 to May 1997 to determine the feasibility of delivering electronic journal articles via the Internet to remote faculty. Articles were scanned into Adobe Acrobat Portable Document Format (PDF) files and delivered to individuals using Multipurpose Internet Mail Extensions (MIME) standard e-mail attachments and the Web. Participants retrieved scanned articles and used the Adobe Acrobat Reader software to view and print files. The pilot test required a special programming effort to automate the client notification and file deletion processes. Test participants were satisfied with the pilot test despite some technical difficulties. Desktop delivery is now offered as a routine delivery method from the UW HSL.

Proceedings of the First Annual NRO-OSL/GSFC-ATS Rideshare Conference

NASA Technical Reports Server (NTRS)

Cutlip, William (Editor)

1999-01-01

This document contains the proceedings of the First Annual NRO-OSL/GSFC-ATS Rideshare Conference. The conference was held April 16-16, 1999, at the Litton/TASC Facility, Dulles, Virginia, and was co-chaired by William Cutlip, Goddard Space Flight Center Access to Space Group, and Jim Liller, National Reconnaissance Office, Office of Space Launch.

Wringing the last drop of optically stimulated luminescence response for accurate dating of glacial sediments

NASA Astrophysics Data System (ADS)

Medialdea, Alicia; Bateman, Mark D.; Evans, David J.; Roberts, David H.; Chiverrell, Richard C.; Clark, Chris D.

2017-04-01

BRITICE-CHRONO is a NERC-funded consortium project of more than 40 researchers aiming to establish the retreat patterns of the last British and Irish Ice Sheet. For this purpose, optically stimulated luminescence (OSL) dating, among other dating techniques, has been used in order to establish accurate chronology. More than 150 samples from glacial environments have been dated and provide key information for modelling of the ice retreat. Nevertheless, luminescence dating of glacial sediments has proven to be challenging: first, glacial sediments were often affected by incomplete bleaching and secondly, quartz grains within the sediments sampled were often characterized by complex luminescence behaviour; characterized by dim signal and low reproducibility. Specific statistical approaches have been used to over come the former to enable the estimated ages to be based on grain populations most likely to have been well bleached. This latest work presents how issues surrounding complex luminescence behaviour were over-come in order to obtain accurate OSL ages. This study has been performed on two samples of bedded sand originated on an ice walled lake plain, in Lincolnshire, UK. Quartz extracts from each sample were artificially bleached and irradiated to known doses. Dose recovery tests have been carried out under different conditions to study the effect of: preheat temperature, thermal quenching, contribution of slow components, hot bleach after a measuring cycles and IR stimulation. Measurements have been performed on different luminescence readers to study the possible contribution of instrument reproducibility. These have shown that a great variability can be observed not only among the studied samples but also within a specific site and even a specific sample. In order to determine an accurate chronology and realistic uncertainties to the estimated ages, this variability must be taken into account. Tight acceptance criteria to measured doses from natural, not exposed, aliquots have been applied. These derived on reproducible dose distributions from which accurate ages could be estimated.

Portable Diagnostics and Rapid Germination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dunn, Zachary Spencer

In the Bioenergy and Defense Department of Sandia National Laboratories, characterization of the BaDx (Bacillus anthracis diagnostic cartridge) was performed and rapid germination chemistry was investigated. BaDx was tested with complex sample matrixes inoculated with Bacillus anthracis, and the trials proved that BaDx will detect Bacillus anthracis in a variety of the medium, such as dirt, serum, blood, milk, and horse fluids. The dimensions of the device were altered to accommodate an E. coli or Listeria lateral flow immunoassay, and using a laser printer, BaDx devices were manufactured to identify E. coli and Listeria. Initial testing with E. coli versionsmore » of BaDx indicate that the device will be viable as a portable diagnostic cartridge. The device would be more effective with faster bacteria germination; hence studies were performed the use of rapid germination chemistry. Trials with calcium dipicolinic acid displayed increased cell germination, as shown by control studies using a microplate reader. Upon lyophilization the rapid germination chemistry failed to change growth patterns, indicating that the calcium dipicolinic acid was not solubilized under the conditions tested. Although incompatible with the portable diagnostic device, the experiments proved that the rapid germination chemistry was effective in increasing cell germination.« less

Portable Microplate Analyzer with a Thermostatic Chamber Based on a Smartphone for On-site Rapid Detection.

PubMed

Wan, Zijian; Zhong, Longjie; Pan, Yuxiang; Li, Hongbo; Zou, Quchao; Su, Kaiqi; Wang, Ping

2017-01-01

A microplate method provides an efficient way to use modern detection technology. However, there are some difficulties concerning on-site detection, such as being non-portable and time-consuming. In this work, a novel portable microplate analyzer with a thermostatic chamber based on a smartphone was designed for rapid on-site detection. An analyzer with a wide-angle lens and an optical filter provides a proper environment for the microplate. A smartphone app-iPlate Monitor was used for RGB analyze of image. After a consistency experiment with a microtiter plate reader (MTPR), the normalized calibration curves were y = 0.7276x + 0.0243 (R 2 = 0.9906) and y = 0.3207x + 0.0094 (R 2 = 0.9917) with a BCA protein kit as well as y = 0.182x + 0.0134 (R 2 = 0.994) and y = 0.0674x + 0.0003 (R 2 = 0.9988) with a glucose kit. The times for obtaining the detection requirement were 15 and 10 min for the BCA protein kit and the glucose kit at 37°C; in contrast, it required more than 30 and 20 min at ambient temperature. Meanwhile, it also showed good repeatability for detections.

OSL dating of a Pleistocene maar: Birket Ram, the Golan heights

USGS Publications Warehouse

Shaanan, U.; Porat, N.; Navon, O.; Weinberger, R.; Calvert, A.; Weinstein, Y.

2011-01-01

Direct dating of maars and their phreatomagmatic deposits is difficult due to the dominance of lithic (host rock) fragments and glassy particles of the juvenile magma. In this paper we demonstrate that optically stimulated luminescence (OSL) dating can be successfully used for age determination of phreatomagmatic deposits. We studied the tuff deposit of Birket Ram, a basanitic maar located at the northern edge of the Golan heights on the western Arabian plate. The maar is underlain by a thick section of Pleistocene basalts, and currently hosts a small lake. It is filled by approximately 90m of lacustrine sediments with radiocarbon ages extrapolated to 108ka at the base. OSL was applied to quartz grains extracted from tuffs and paleosols in order to set the time frame of the phreatomagmatism at the site. A maximum age constraint of 179??13ka was determined for a paleosol that underlies the maar ejecta. Quartz grains from two layers in the tuff section yielded a direct age of 129??6ka for the phreatomagmatic eruption. A younger age of 104??7ka, which was determined for a tuff layer underlying a basaltic flow, was attributed to thermal resetting during the lava emplacement. This was confirmed by an 40Ar/39Ar age of 101??3ka determined on the overlying basalt. The internal consistency of the OSL ages and the agreement with the 40Ar/39Ar age determination as well as with previous estimates demonstrates the potential of OSL for maar dating. ?? 2010 Elsevier B.V.

Practical calibration curve of small-type optically stimulated luminescence (OSL) dosimeter for evaluation of entrance skin dose in the diagnostic X-ray region.

PubMed

Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Kobayashi, Ikuo

2015-07-01

For X-ray diagnosis, the proper management of the entrance skin dose (ESD) is important. Recently, a small-type optically stimulated luminescence dosimeter (nanoDot OSL dosimeter) was made commercially available by Landauer, and it is hoped that it will be used for ESD measurements in clinical settings. Our objectives in the present study were to propose a method for calibrating the ESD measured with the nanoDot OSL dosimeter and to evaluate its accuracy. The reference ESD is assumed to be based on an air kerma with consideration of a well-known back scatter factor. We examined the characteristics of the nanoDot OSL dosimeter using two experimental conditions: a free air irradiation to derive the air kerma, and a phantom experiment to determine the ESD. For evaluation of the ability to measure the ESD, a calibration curve for the nanoDot OSL dosimeter was determined in which the air kerma and/or the ESD measured with an ionization chamber were used as references. As a result, we found that the calibration curve for the air kerma was determined with an accuracy of 5 %. Furthermore, the calibration curve was applied to the ESD estimation. The accuracy of the ESD obtained was estimated to be 15 %. The origin of these uncertainties was examined based on published papers and Monte-Carlo simulation. Most of the uncertainties were caused by the systematic uncertainty of the reading system and the differences in efficiency corresponding to different X-ray energies.

Overview of physical dosimetry methods for triage application integrated in the new European network RENEB.

PubMed

Trompier, François; Burbidge, Christopher; Bassinet, Céline; Baumann, Marion; Bortolin, Emanuela; De Angelis, Cinzia; Eakins, Jonathan; Della Monaca, Sara; Fattibene, Paola; Quattrini, Maria Cristina; Tanner, Rick; Wieser, Albrecht; Woda, Clemens

2017-01-01

In the EC-funded project RENEB (Realizing the European Network in Biodosimetry), physical methods applied to fortuitous dosimetric materials are used to complement biological dosimetry, to increase dose assessment capacity for large-scale radiation/nuclear accidents. This paper describes the work performed to implement Optically Stimulated Luminescence (OSL) and Electron Paramagnetic Resonance (EPR) dosimetry techniques. OSL is applied to electronic components and EPR to touch-screen glass from mobile phones. To implement these new approaches, several blind tests and inter-laboratory comparisons (ILC) were organized for each assay. OSL systems have shown good performances. EPR systems also show good performance in controlled conditions, but ILC have also demonstrated that post-irradiation exposure to sunlight increases the complexity of the EPR signal analysis. Physically-based dosimetry techniques present high capacity, new possibilities for accident dosimetry, especially in the case of large-scale events. Some of the techniques applied can be considered as operational (e.g. OSL on Surface Mounting Devices [SMD]) and provide a large increase of measurement capacity for existing networks. Other techniques and devices currently undergoing validation or development in Europe could lead to considerable increases in the capacity of the RENEB accident dosimetry network.

Thermoluminescence and optically stimulated luminescence properties of Dy3+-doped CaO-Al2O3-B2O3-based glasses

NASA Astrophysics Data System (ADS)

Yahaba, T.; Fujimoto, Y.; Yanagida, T.; Koshimizu, M.; Tanaka, H.; Saeki, K.; Asai, K.

2017-02-01

We developed Dy3+-doped CaO-Al2O3-B2O3 based glasses with Dy concentrations of 0.5, 1.0, and 2.0 mol% using a melt-quenching technique. The as-synthesized glasses were applicable as materials exhibiting thermoluminescence (TL) and optically stimulated luminescence (OSL). The optical and radiation response properties of the glasses were characterized. In the photoluminescence (PL) spectra, two emission bands due to the 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions of Dy3+ were observed at 480 and 580 nm. In the OSL spectra, the emission band due to the 4F9/2 → 6H15/2 transition of Dy3+ was observed. Excellent TL and OSL responses were observed for dose ranges of 0.1-90 Gy. In addition, TL fading behavior was better than that of OSL in term of the long-time storage. These results indicate that the Dy3+-doped CaO-Al2O3-B2O3-based glasses are applicable as TL materials.

TL and OSL properties of Mn2+-doped MgGa2O4 phosphor

NASA Astrophysics Data System (ADS)

Luchechko, A.; Zhydachevskyy, Ya; Maraba, D.; Bulur, E.; Ubizskii, S.; Kravets, O.

2018-04-01

The oxide MgGa2O4 spinel ceramics doped with Mn2+ ions was synthesized by a solid-state reaction at 1200 °C in air. The activator concentration was equal 0.05 mol% of MnO. Phase purity of the synthesized samples was analyzed by X-ray diffraction technique. This spinel ceramics show efficient green emission in the range from 470 to 550 nm with a maximum at about 505 nm under UV or X-ray excitations, which is due to Mn2+ ions. MgGa2O4: Mn2+ exhibits intense thermoluminescence (TL) and optically stimulated luminescence (OSL) after influence of ionizing radiation. Are complex nature of the TL glow curves is associated with a significant number of structural defects that are responsible for the formation of shallow and deep electron traps. In this work, time-resolved OSL characteristics of the samples exposed to beta particles are reported for the first time. A light from green LED was used for optical stimulation. Obtained TL and OSL results suggest MgGa2O4:Mn2+ as perspective material for further research and possible application in radiation dosimetry.

Luminescence dating of ancient Darhad basin, Mongolia

NASA Astrophysics Data System (ADS)

Cheul Kim, Jin; Yi, Sangheon; Lim, Jaesoo; Kim, Ju-Yong

2016-04-01

Darhad basin is located in the northern Mongolia, in the western end of the Baikal Rift Zone. In contrast to the neighboring Lake Hovsgol, Mongolia's largest and deepest lake, the Darhad is a drained lake basin. It is ~100 km long (north-south), 20-40 km wide and covered by sediments which locally exceed 500 m thickness (Zorin et al., 1989). Darhad basin is characterized by alternating episodes of expansion and desiccation that are closely related with the Pleistocene damming events. Previous studies of the Darhad Basin suggest that the last paleolake was dammed by a large glacier or the sediments (Selivanov, 1967, 1968; Krivonogov et al., 2005; Gillespie et al., 2008). Especially, recent expansion of the paleolake might be caused by the two glacial maxima during MIS 4 and 2. However, glacier-dammed lakes might be short-lived, dried up and permafrost occurred in the drained basin during the Holocene period. The uppermost paleolake sediments (13.2 m depth) are exposed following the curvature of the meandering river (called "Hodon outcrop"). It is considered the most likely site for the youngest paleolake sediments because it is distributed in the northern middle part of the paleolake. Krivonogov et al. 2012 described the Hodon outcrop with the sedimentological and chronological data. Age dating of 16 samples (11 mollusk shells, 5 wood fragments) indicated that Hodon outcrop sediments were deposited between 10.1±7 and 4.9±5 ka. However, the ages obtained on shells much older dates than the matched wood samples because of ingestion of old carbon by mollusks. The age difference between shells and wood fragments is a minimum of 1.73 ka and a maximum of 3.41 ka (average 2.5 ka). In this case, 14C ages from shells should be corrected with appropriate correction factor. However, the old carbon effects could vary temperally and spatially in the Darhad paleolake. The limited number of the 14C ages from wood fragments result in a simple linear trend in the depth-age curve. Thus, age control on existing 14C ages from this site is limited, chronological interpretation based on the 14C ages is still incomplete in Hodon outcrop sediments. OSL (Optically Stimulated Luminescence) is an alternative method for dating to overcome the problems associated with 14C methods. OSL has been extensively used for dating arctic sediments (Thomas et al., 2006; more). Previous optical ages on Darhad paleolake sediments obtained using IRSL (Infrared-stimulated luminescence) on feldspars (Gillespie et al., 2008; Batbaatar et al., 2009). Feldspar has much brighter luminescence than quartz, while the OSL signal of feldspars bleaches at least one order of magnitude slower than the OSL signal of quartz (Godfrey-Smith et al., 1988; Huntly and Lamothe, 2001; Mauz and Bungenstock, 2007; Kim et al., 2012). In glaciofluvial, glaciolacustrine environments, inadequate bleaching of the OSL signal is known to be a potential problem of burial ages (Thomas et al., 2006). OSL dating of permafrost deposits may also involve uncertainty about the inhomogeneous radiation field surrounding the dosimeter and the absorption of ionizing energy alternately by water and ice in a not-constant pore volume (Haeberli et al., 2003). In this study, we test the applicability of quartz OSL dating for the uppermost paleolake sediments in the Hodon outcrop of the Darhad basin. The OSL results were systematically compared with additional radiocarbon ages from wood fragments to conclude the reliability of the OSL dates and to construct intensive chronology for Late-Pleistocene Darhad paleolake. To evaluate the time of recent expansion of the paleolake, the northern piedmont (Talyn outcrop) of the basin was dated by OSL.

Emergency OSL/TL dosimetry with integrated circuits from mobile phones

NASA Astrophysics Data System (ADS)

Sholom, S.; McKeever, S. W. S.

2014-09-01

Integrated circuits (ICs) from several mobile phones were studied as possible emergency dosimeters using optically stimulated luminescence (OSL) and thermoluminescence (TL) techniques. Measurement protocols were developed for ICs that take into consideration the effect of sensitization of the samples with increasing dose as well as fading of the signals after sample exposure. It was found that the OSL technique has a higher sensitivity with ICs when compared to TL, while the TL signals were characterized by better stability with time after exposure. Values of minimum measurable doses were found to be in the range between a few tens of mGy and several tens of mGy for the tested samples. It was concluded that ICs from mobile phones could be used for emergency dose reconstruction.

Species-Level Identification of Orthopoxviruses with an Oligonucleotide Microchip

PubMed Central

Lapa, Sergey; Mikheev, Maxim; Shchelkunov, Sergei; Mikhailovich, Vladimir; Sobolev, Alexander; Blinov, Vladimir; Babkin, Igor; Guskov, Alexander; Sokunova, Elena; Zasedatelev, Alexander; Sandakhchiev, Lev; Mirzabekov, Andrei

2002-01-01

A method for species-specific detection of orthopoxviruses pathogenic for humans and animals is described. The method is based on hybridization of a fluorescently labeled amplified DNA specimen with the oligonucleotide DNA probes immobilized on a microchip (MAGIChip). The probes identify species-specific sites within the crmB gene encoding the viral analogue of tumor necrosis factor receptor, one of the most important determinants of pathogenicity in this genus of viruses. The diagnostic procedure takes 6 h and does not require any sophisticated equipment (a portable fluorescence reader can be used). PMID:11880388

Luminescence chronology of the loess record from the Tönchesberg section - a comparison of using quartz and feldspar as dosimeter to extend the age range beyond the Eemian

NASA Astrophysics Data System (ADS)

Dorothe Schmidt, Esther; Frechen, Manfred; Murray, Andrew S.; Tsukamoto, Sumiko

2010-05-01

The loess-paleosol sequences of the Tönchesberg section, located in the East Eifel Volcanic field (Germany) provide an excellent climate archive of the late Middle and the Upper Pleistocene in the Middle Rhine area. Loess deposits from the last Glacial (Würmian) and the penultimate Glacial (Rissian) are up to 12 m and 15 m thick, respectively, and intercalated by palaeosols. Optically stimulated luminescence (OSL), thermally transferred optically stimulated luminescence (TT-OSL) and infrared stimulated luminescence (IRSL) measurements were carried out on 14 samples from the Tönchesberg section to determine the deposition age and to set up a more reliable chronological framework for the penultimate and last interglacial-glacial cycle. The fine-grained quartz OSL and polymineral IRSL ages are in good agreement with each other and also with the geologically estimated age, but the quartz TT-OSL ages are overestimated. The OSL and IRSL ages range from 16.8 ± 1.2 to 189 ± 16 ka indicating that the youngest loess and the weakly developed soils were deposited during marine isotope stage (MIS) 2 and 3 and that the two marker loess were most likely accumulated in the transition MIS 4/5. Loess and reworked loess postdating the Eemian soil yield ages of 110-115 ka indicating that these deposits very likely correlate to MIS 5d. Loess deposits taken below the Eemian soil are attributed to the transition MIS 6/7. A weakly developed soil above the Tönchesberg scoria yield an age of 189 ± 16 ka indicating an interstadial soil formation during MIS 7. This is in good agreement with preliminary 40Ar/39Ar-ages for the Tönchesberg scoria and the intercalated tephra layers. Reliable age estimates up to ~70 ka could be obtained using quartz OSL and up to ~190 ka using the pulsed post-IR IR signal from feldspar. Hence the infrared stimulated luminescence (IRSL) is considered as the best approach to date the loess from the Middle Rhine area > 70 ka.

Luminescence ages for alluvial-fan deposits in Southern Death Valley: Implications for climate-driven sedimentation along a tectonically active mountain front

USGS Publications Warehouse

Sohn, M.F.; Mahan, S.A.; Knott, J.R.; Bowman, D.D.

2007-01-01

Controversy exists over whether alluvial-fan sedimentation along tectonically active mountain fronts is driven by climatic changes or tectonics. Knowing the age of sedimentation is the key to understanding the relationship between sedimentation and its cause. Alluvial-fan deposits in Death Valley and throughout the arid southwestern United States have long been the subjects of study, but their ages have generally eluded researchers until recently. Most mapping efforts have recognized at least four major relative-age groupings (Q1 (oldest), Q2, Q3, and Q4 (youngest)), using observed changes in surface soils and morphology, relation to the drainage net, and development of desert pavement. Obtaining numerical age determinations for these morphologic stages has proven challenging. We report the first optically stimulated luminescence (OSL) ages for three of these four stages deposited within alluvial-fans along the tectonically active Black Mountains of Death Valley. Deposits showing distinct, remnant bar and swale topography (Q3b) have OSL ages from 7 to 4 ka., whereas those with moderate to poorly developed desert pavement and located farther above the active channel (Q3a) have OSL ages from 17 to 11 ka. Geomorphically older deposits with well-developed desert pavement (Q2d) have OSL ages ???25 ka. Using this OSL-based chronology, we note that alluvial-fan deposition along this tectonically active mountain front corresponds to both wet-to-dry and dry-to-wet climate changes recorded globally and regionally. These findings underscore the influence of climate change on alluvial fan deposition in arid and semi-arid regions. ?? 2007 Elsevier Ltd and INQUA.

Comparison of ferumoxytol-enhanced MRA with conventional angiography for assessment of severity of transplant renal artery stenosis.

PubMed

Fananapazir, Ghaneh; Bashir, Mustafa R; Corwin, Michael T; Lamba, Ramit; Vu, Catherine T; Troppmann, Christoph

2017-03-01

To determine the accuracy of ferumoxytol-enhanced magnetic resonance angiography (MRA) in assessing the severity of transplant renal artery stenosis (TRAS), using digital subtraction angiography (DSA) as the reference standard. Our Institutional Review Board approved this retrospective, Health Insurance Portability and Accountability Act-compliant study. Thirty-three patients with documented clinical suspicion for TRAS (elevated serum creatinine, refractory hypertension, edema, and/or audible bruit) and/or concerning sonographic findings (elevated renal artery velocity and/or intraparenchymal parvus tardus waveforms) underwent a 1.5T MRA with ferumoxytol prior to DSA. All DSAs were independently reviewed by an interventional radiologist and served as the reference standard. The MRAs were reviewed by three readers who were blinded to the ultrasound and DSA findings for the presence and severity of TRAS. Sensitivity, specificity, and accuracy for identifying substantial stenoses (>50%) were determined. Intraclass correlation coefficients (ICCs) were calculated among readers. Mean differences between the percent stenosis from each MRA reader and DSA were calculated. On DSA, a total of 42 stenoses were identified in the 33 patients. The sensitivity, specificity, and accuracy of MRA in detecting substantial stenoses were 100%, 75-87.5%, and 95.2-97.6%, respectively, among the readers. There was excellent agreement among readers as to the percent stenosis (ICC = 0.82). MRA overestimated the degree of stenosis by 3.9-9.6% compared to DSA. Ferumoxytol-enhanced MRA provides high sensitivity, specificity, and accuracy for determining the severity of TRAS. Our results suggest that it can potentially be used as a noninvasive examination following ultrasound to reduce the number of unnecessary conventional angiograms. 3 J. Magn. Reson. Imaging 2017;45:779-785. © 2016 International Society for Magnetic Resonance in Medicine.

Unprecedented last-glacial mass accumulation rates determined by luminescence dating of loess from western Nebraska

USGS Publications Warehouse

Roberts, H.M.; Muhs, D.R.; Wintle, A.G.; Duller, G.A.T.; Bettis, E. Arthur

2003-01-01

A high-resolution chronology for Peoria (last glacial period) Loess from three sites in Nebraska, midcontinental North America, is determined by applying optically stimulated luminescence (OSL) dating to 35-50 ??m quartz. At Bignell Hill, Nebraska, an OSL age of 25,000 yr near the contact of Peoria Loess with the underlying Gilman Canyon Formation shows that dust accumulation occurred early during the last glacial maximum (LGM), whereas at Devil's Den and Eustis, Nebraska, basal OSL ages are significantly younger (18,000 and 21,000 yr, respectively). At all three localities, dust accumulation ended at some time after 14,000 yr ago. Mass accumulation rates (MARs) for western Nebraska, calculated using the OSL ages, are extremely high from 18,000 to 14,000 yr-much higher than those calculated for any other pre-Holocene location worldwide. These unprecedented MARs coincide with the timing of a mismatch between paleoenvironmental evidence from central North America, and the paleoclimate simulations from atmospheric global circulation models (AGCMs). We infer that the high atmospheric dust loading implied by these MARs may have played an important role, through radiative forcing, in maintaining a colder-than-present climate over central North America for several thousand years after summer insolation exceeded present-day values. ?? 2003 Elsevier Science (USA). All rights reserved.

The applicability of OSL as a sedimentological proxy: new avenues to distinguish extreme events

NASA Astrophysics Data System (ADS)

Lopez, G. I.

2012-12-01

Signature underwater tsunami deposits have been relatively recently found in the upper Mediterranean shelf offshore Israel. They have been attributed as a potential cause for the demise of the ancient Roman city of Caesarea Maritima and its artificial Herodian harbour of Sebastos. Present annual large winter storm activity (2010-2011; waves heights up to 14 m) has severely impacted the area, showing increased coastal erosion and rigorous movement of nearshore sands, complicating the stratigraphical histories of the near offshore record. Recent sedimentological and geoarchaeological studies conducted in and around the harbour have been aimed to investigate extreme event characterization by different means, using Optically Stimulated Luminescence (OSL). A comparative study of modern and palaeo-storm sediments was launched in order to obtain physical correlation between offshore sediments, enabling further comparison with historical tsunami deposits, as well as modern and ancient sands emplaced during normal marine conditions. A suite of previously collected and identified sediment samples was selected from the same area where the modern storm analogues were collected. The palaeo-samples came from long-vertical hydraulic percussion cores (14-30 m depths) and small horizontal tubes pushed into excavated underwater sediment walls (2-12 m depths). The uniqueness of OSL relays on its capacity to date the last time a mineral grain was effectively exposed to sunlight, just prior to its burial. It is intrinsically related to final depositional process, which should reflect the completeness of the OSL signal resetting (zeroing process), evidenced by the normality and modality of the Equivalent Dose (DE) distribution. In Optical Dating, DE over-dispersion values have been used as a measure of inhomogeneitiy in the natural palaeo-dose of sediments. Such heterogeneity can be due to an array of causes, including insufficient zeroing during transport and deposition, or turbation processes after burial. Environments where sediments are well exposed to daylight at deposition (e.g. aeolian and some coastal) do not show extreme over-dispersion values but rather well clustered DE's as noted by probability-distribution plots. The degrees of variance and skewness of Gaussian or relative-probability distributions are intrinsically related to the scatter factor. Hence, the latter could be used to differentiate between depositional mechanisms and/or environmental settings. In this study, the single-aliquot regenerative-dose (SAR) protocol was used to measure the OSL signals from single grains of quartz from tsunami, storm and normal marine conditions deposits. Over-dispersion analyses were conducted on all samples. Preliminary results suggest the possibility of differentiating between all three types of deposits based on pre-established over-dispersion values and representative single-dose population distributions. Further comparative OSL experiments are currently being carried out on other known tsunamigenic analogues to further evaluate OSL signal behaviours and constrain the findings (2011 Tohoku Tsunami; 1979 night Petatlán Tsunami). Rather than a dating tool, OSL was used to identify signal patterns exclusive to known depositional conditions, in hope of applying it as sedimentological proxy in event stratigraphy and palaeoseismic tsunami research.

Investigating Advances in the Acquisition of Systems Based on Open Architecture and Open Source Software

DTIC Science & Technology

2011-08-01

dominates the global mobile application market and mobile computing software ecosystems. But overall, OA systems are not necessarily excluded from...License 3.0 (OSL)  Corel Transactional License ( CTL ) The licenses were chosen to represent a variety of kinds of licenses, and include one...proprietary ( CTL ), three academic (Apache, BSD, MIT), and six reciprocal licenses (CPL, EPL, GPL, LGPL, MPL, OSL) that take varying approaches in

TL, OSL and C-14 dating results of the sediments and bricks from mummified nuns' grave.

PubMed

Tudela, Diego R G; Tatumi, Sonia H; Yee, Márcio; Brito, Silvio L M; Morais, José L; Morais, Daisy de; Piedade, Silvia C; Munita, Casimiro S P; Hazenfratz, Roberto

2012-06-01

This paper presents the results of TL and OSL dating of soil and fragments of bricks from a grave, which was occupied by two mummified nuns, found at "Luz" Monastery, located in the state of São Paulo, Brazil. The TL and OSL ages were compared to C-14 dating ones obtained from bone collagens of the mummies. The majority of the ages is related to the eighteenth century. The gamma-ray spectroscopy was used to evaluate natural radioisotope concentrations in the samples, and by using these concentrations the annual dose rates, from 3.0 to 5.3 Gy/kyr, were obtained. Neutron activation analysis was performed and the radioisotope contents results are in agreement with those obtained by gamma-ray spectroscopy. The contents of U, Th and Ce elements were higher than those found in usual sediments.

Luminescence quartz dating of lime mortars. A first research approach.

PubMed

Zacharias, N; Mauz, B; Michael, C T

2002-01-01

Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870 +/- 230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095 +/- 190 a.

Synthesis and luminescence properties of KSrPO4:Eu2+ phosphor for radiation dosimetry

NASA Astrophysics Data System (ADS)

Palan, C. B.; Bajaj, N. S.; Omanwar, S. K.

2016-05-01

The KSrPO4:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO4:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO4:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al2O3:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activation energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.

Surface dose measurement for helical tomotherapy.

PubMed

Snir, Jonatan A; Mosalaei, Homeira; Jordan, Kevin; Yartsev, Slav

2011-06-01

To compare the surface dose measurements made by different dosimeters for the helical tomotherapy (HT) plan in the case of the target close to the surface. Surface dose measurements in different points for the HT plan to deliver 2 Gy to the planning target volume (PTV) at 5 mm below the surface of the cylindrical phantom were performed by radiochromic films, single use metal oxide semiconductor field-effect transistor (MOSFET) dosimeters, silicon IVD QED diode, and optically stimulated luminescence (OSL) dosimeters. The measured doses by all dosimeters were within 12 +/- 8% difference of each other. Radiochromic films, EBT, and EBT2, provide high spatial resolution, although it is difficult to get accurate measurements of dose. Both the OSL and QED measured similar dose to that of the MOSFET detectors. The QED dosimeter is promising as a reusable on-line wireless dosimeter, while the OSL dosimeters are easier to use, require minimum setup time and are very precise.

Chronology of Quaternary coastal aeolianite deposition and the drowned shorelines of southwestern Western Australia - a reappraisal

NASA Astrophysics Data System (ADS)

Brooke, B. P.; Olley, J. M.; Pietsch, T.; Playford, P. E.; Haines, P. W.; Murray-Wallace, C. V.; Woodroffe, C. D.

2014-06-01

Aeolianite successions of low-gradient continental margins commonly show complex records of coastal dune deposition linked to a wide range of sea-level positions and climatic periods of the middle and late Pleistocene, recording both regional and broader-scale drivers of sediment production, coastal dune development and landform preservation. To better characterise the general pattern of sedimentation that occurs over Quaternary glacial-interglacial cycles on low-gradient, temperate carbonate continental shelves we examine the morphology, stratigraphy and age of aeolianite deposits in the Perth region, Western Australia. This includes an analysis of well-defined drowned coastal landforms preserved on the adjacent shelf. New and previously published optical ages provide a preliminary timeframe for the deposition of aeolianite in the Perth region and on Rottnest Island, 17 km offshore. An extensive aeolianite ridge near Perth, representing a former barrier, has Optically Stimulated Luminesence (OSL) ages that range from 120 ± 12 to 103 ± 10 ka (MIS 5e-5a in the context of associated age uncertainties). OSL ages for an exposure in the same ridge 2.5 km inland, record the onlap of much older aeolianite, OSL age 415 ± 70 ka, by shell-rich estuarine beds, OSL age 290 ± 30 ka. A further 5.5 km inland from the coast, two thick aeolianite units, separated by a well-developed palaeosol, have stratigraphically consistent OSL ages of 310 ± 30 and 155 ± 20 ka. In contrast, aeolianite units that form the northern coast of Rottnest Island have OSL ages of 77 ± 12 ka and 27 ± 5 ka. The new OSL ages and previously reported TL and U/Th ages indicate that the bulk of the island comprises dunes deposited around the end of the Last Interglacial sensu lato (MIS 5a-4) and during the Last Glacial (MIS 4-2), accumulating over a Last Interglacial coral reef and basal calcarenite. Drowned barrier and dune landforms preserved on the adjacent continental shelf reveal that barriers were formed during periods of intermediate sea level (e.g. MIS 3) and significant dune mobility occurred when the shelf was subaerially exposed. The pattern of shelf sedimentation discernible in the Perth region - large-scale coastal carbonate dune deposition during periods of high and intermediate sea level and reactivation during glacial lowstands - is largely consistent with published stratigraphic and age data for large-scale aeolianite deposits on other low-gradient carbonate shelves. Based on these data, a general model is proposed for the cycle of Quaternary sedimentation and landform evolution that occurs on these shelves, which are dynamic sedimentary environments with coastal landforms and sedimentary successions that are very sensitive to erosion and sediment reworking.

Luminescence and Radiocarbon dating of roman time harbour sediments from Cologne - A comparison of different methods

NASA Astrophysics Data System (ADS)

Lauer, Tobias; Frechen, Manfred; Fuchs, Magret C.; Trier, Marcus; Tsukamoto, Sumiko

2010-05-01

Optically stimulated luminescence (OSL) dating was applied to fluvial and colluvial deposits which were taken from a roman time harbour basin in Cologne. Hence, independent age control was given by roman artefacts (coins, bricks) of known age and by three radiocarbon data. For one sample (well sorted fluvial sand), a single aliquot regenerative (SAR) protocol was applied to coarse grain quartz. A large number of equivalent doses (80) were collected and after De-measurements, different statistical approaches were tested. The results show, that calculating the age by using the Mean or Median of all accepted De-values yields OSL ages of 3.5 ± 0.3 ka and 2.8 ± 0.3 ka, respectively, what would be significantly too old. The application of the Leading Edge Method (Lepper & McKeever 2002), the statistical approach after Fuchs & Lang (2001) or the Minimum Age Method (MAM3) after Galbraith et al. (1999) yield OSL age estimates of 2.0 ± 0.1 ka, 2.1 ± 0.1 ka and 1.7 ± 0.6 ka, respectively. Those ages fit very well to the 14C-ages and are in better agreement with the known archaeological background. For the colluvial sample, the quartz OSL signal was effected by feldspar impurities. For this sample, different methodological approaches were tested to see which one has the best potential to minimize the feldspar contribution. Therefore the post-IR blue stimulated quartz luminescence was recorded. The quartz signal was measured using continuous wave (CW) and pulsed OSL (POSL). For the CW measurements, it was tested if a prior IR-bleach @ 50°C or @ 225°C has better potential for minimizing the feldspar signal. In this case, an IR-bleach @ 225°C (Buylaert et al. in press) was the most effective way to obtain a higher purity of the quartz OSL signal. Buylaert, J.P., Murray, A.S., Thomsen, K.J., Jain, M.: The effect of preheating on the IRSL signal from feldspar. In press. - Radiat. Meas., special issue, LED08. Fuchs, M. & Lang, A. (2001): OSL dating of coarse-grain fluvial quartz using single-aliquot protocols on sediments from NE Peloponnese, Greece. - Quaternary Science Reviews, 20: 783-787. Galbraith, R. F., Roberts, R. G., Laslett, G. M., Yoshida, H. & Olley, J. M. (1999): Optical dating of single and multiple grains of quartz from Jinmium Rock Shelter, northern Australia: Part 1, experimental design and statistical models. - Archaeometry, 41: 339-364. Lepper, K. & McKeever, S.W.S. (2002): An objective methodology for dose distribution analysis. Radiation Protection Dosimetry. - Solid State Dosimetry, 101: 349-352.

A hand-powered, portable, low-cost centrifuge for diagnosing anemia in low-resource settings.

PubMed

Brown, Jocelyn; Theis, Lauren; Kerr, Lila; Zakhidova, Nazima; O'Connor, Kelly; Uthman, Margaret; Oden, Z Maria; Richards-Kortum, Rebecca

2011-08-01

This report describes the development of a hand-powered centrifuge to determine hematocrit values in low-resource settings. A hand-powered centrifuge was constructed by using a salad spinner. Hematocrit values were measured by using the hand-powered device, and results were compared with those of a benchtop centrifuge. The packed cell volume (PCV) measured with the hand-powered device correlated linearly with results obtained with a benchtop centrifuge (r = 0.986, P < 0.001). The PCVs measured with the hand-powered centrifuge were consistently 1.14 times higher than those measured with the benchtop system. The 14% increase in PCV measured with the hand-powered centrifuge is caused by increased plasma trapped in the cell column. The reader card was adjusted to compensate for trapped plasma. A hand-powered centrifuge and calibrated reader card can be constructed for U.S. $35 and can accurately determine hematocrit values. It is suitable for use in low-resource settings because it is mechanically-powered, inexpensive, and accurate.

A Hand-Powered, Portable, Low-Cost Centrifuge for Diagnosing Anemia in Low-Resource Settings

PubMed Central

Brown, Jocelyn; Theis, Lauren; Kerr, Lila; Zakhidova, Nazima; O'Connor, Kelly; Uthman, Margaret; Oden, Z. Maria; Richards-Kortum, Rebecca

2011-01-01

This report describes the development of a hand-powered centrifuge to determine hematocrit values in low-resource settings. A hand-powered centrifuge was constructed by using a salad spinner. Hematocrit values were measured by using the hand-powered device, and results were compared with those of a benchtop centrifuge. The packed cell volume (PCV) measured with the hand-powered device correlated linearly with results obtained with a benchtop centrifuge (r = 0.986, P < 0.001). The PCVs measured with the hand-powered centrifuge were consistently 1.14 times higher than those measured with the benchtop system. The 14% increase in PCV measured with the hand-powered centrifuge is caused by increased plasma trapped in the cell column. The reader card was adjusted to compensate for trapped plasma. A hand-powered centrifuge and calibrated reader card can be constructed for U.S. $35 and can accurately determine hematocrit values. It is suitable for use in low-resource settings because it is mechanically-powered, inexpensive, and accurate. PMID:21813855

WRAP low level waste restricted waste management (LLW RWM) glovebox acceptance test report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leist, K.J.

1997-11-24

On April 22, 1997, the Low Level Waste Restricted Waste Management (LLW RWM) glovebox was tested using acceptance test procedure 13027A-87. Mr. Robert L. Warmenhoven served as test director, Mr. Kendrick Leist acted as test operator and test witness, and Michael Lane provided miscellaneous software support. The primary focus of the glovebox acceptance test was to examine glovebox control system interlocks, operator Interface Unit (OIU) menus, alarms, and messages. Basic drum port and lift table control sequences were demonstrated. OIU menus, messages, and alarm sequences were examined, with few exceptions noted. Barcode testing was bypassed, due to the lack ofmore » installed equipment as well as the switch from basic reliance on fixed bar code readers to the enhanced use of portable bar code readers. Bar code testing was completed during performance of the LLW RWM OTP. Mechanical and control deficiencies were documented as Test Exceptions during performance of this Acceptance Test. These items are attached as Appendix A to this report.« less

Measurement of dose given by Co-60 in radiotherapy with TLD-500

NASA Astrophysics Data System (ADS)

Tanır, Güneş; Cengiz, Ferhat; Hicabi Bölükdemir, M.

2012-04-01

The uses of dosimeters based on optically stimulated luminescence technique have become widespread in clinical applications. In the present study, the dose values given by Cobalt-60 radiotherapy machine were measured with optically stimulated luminescence (OSL) technique using TLD-500 and compared with those of commonly used ionization chamber dosimeter system. The percentage depth dose (DD%) values and graphs were formed. OSL system with TLD-500 can be reliably used as medical and personal dosimeter.

Performance and stability of an expanded granular sludge bed reactor modified with zeolite addition subjected to step increases of organic loading rate (OLR) and to organic shock load (OSL).

PubMed

Pérez-Pérez, T; Pereda-Reyes, I; Pozzi, E; Oliva-Merencio, D; Zaiat, M

2018-01-01

This paper shows the effect of organic shock loads (OSLs) on the anaerobic digestion (AD) of synthetic swine wastewater using an expanded granular sludge bed (EGSB) reactor modified with zeolite. Two reactors (R1 and R2), each with an effective volume of 3.04 L, were operated for 180 days at a controlled temperature of 30 °C and hydraulic retention time of 12 h. In the case of R2, 120 g of zeolite was added. The reactors were operated with an up-flow velocity of 6 m/h. The evolution of pH, total Kjeldahl nitrogen, chemical oxygen demand (COD) and volatile fatty acids (VFAs) was monitored during the AD process with OSL and increases in the organic loading rate (OLR). In addition, the microbial composition and changes in the structure of the bacterial and archaeal communities were assessed. The principal results demonstrate that the presence of zeolite in an EGSB reactor provides a more stable process at higher OLRs and after applying OSL, based on both COD and VFA accumulation, which presented with significant differences compared to the control. Denaturing gradient gel electrophoresis band profiles indicated differences in the populations of Bacteria and Archaea between the R1 and R2 reactors, attributed to the presence of zeolite.

Emergency Optically Stimulated Luminescence Dosimetry Using Different Materials

PubMed Central

Sholom, S; DeWitt, R; Simon, SL; Bouville, A; McKeever, SWS

2011-01-01

Several materials were tested as possible individual emergency dosimeters using Optically Stimulated Luminescence (OSL) as means to assess the exposure. Materials investigated included human nails, business cards and plastic buttons. The OSL properties of these materials were studied in comparison with those of teeth. Most samples revealed OSL signals only after exposure to ionizing radiation; some samples of business cards, however, displayed a strong initial “native” signal (i.e. existing in the samples prior to irradiation). The sensitivity (minimum measurable dose) of the samples was found to vary significantly from sample to sample of the same material and was in the range from several tens of mGy to a few dozens of Gy. The dose response curves were linear for doses below 10 Gy. Fading of the OSL signals was estimated for different lenghts of times and found to be ~95%, 45%, 30% and 15% for samples of teeth, business cards, buttons and nails, respectively, following storage at room temperature in the dark for a period of 3 weeks after exposure. For samples stored under routine laboratory light, fading was much faster and the radiation-induced signals almost disappeared after a few hours of such illumination. It was concluded that the tested materials could be used in triage situations to detect and estimate the possible overexposure of individuals if the measurements can be performed soon enough after exposure. PMID:22125409

Measurement of radiation dose with BeO dosimeters using optically stimulated luminescence technique in radiotherapy applications.

PubMed

Şahin, Serdar; Güneş Tanır, A; Meriç, Niyazi; Aydınkarahaliloğlu, Ercan

2015-09-01

The radiation dose delivered to the target by using different radiotherapy applications has been measured with the help of beryllium oxide (BeO) dosimeters to be placed inside the rando phantom. Three-Dimensional Conformal Radiotherapy (3DCRT), Intensity-Modulated Radiotherapy (IMRT) and Intensity-Modulated Arc Therapy (IMAT) have been used as radiotherapy application. Individual treatment plans have been made for the three radiotherapy applications of rando phantom. The section 4 on the phantom was selected as target and 200 cGy doses were delivered. After the dosimeters placed on section 4 (target) and the sections 2 and 6 (non-target) were irradiated, the result was read through the OSL technique on the Risø TL/OSL system. This procedure was repeated three times for each radiotherapy application. The doses delivered to the target and the non-target sections as a result of the 3DCRT, IMRT and IMAT plans were analyzed. The doses received by the target were measured as 204.71 cGy, 204.76 cGy and 205.65 cGy, respectively. The dose values obtained from treatment planning system (TPS) were compared to the dose values obtained using the OSL technique. It has been concluded that, the radiation dose can be measured with the OSL technique by using BeO dosimeters in medical practices. Copyright © 2015 Elsevier Ltd. All rights reserved.

Emergency Optically Stimulated Luminescence Dosimetry Using Different Materials.

PubMed

Sholom, S; Dewitt, R; Simon, Sl; Bouville, A; McKeever, Sws

2011-12-01

Several materials were tested as possible individual emergency dosimeters using Optically Stimulated Luminescence (OSL) as means to assess the exposure. Materials investigated included human nails, business cards and plastic buttons. The OSL properties of these materials were studied in comparison with those of teeth. Most samples revealed OSL signals only after exposure to ionizing radiation; some samples of business cards, however, displayed a strong initial "native" signal (i.e. existing in the samples prior to irradiation). The sensitivity (minimum measurable dose) of the samples was found to vary significantly from sample to sample of the same material and was in the range from several tens of mGy to a few dozens of Gy. The dose response curves were linear for doses below 10 Gy. Fading of the OSL signals was estimated for different lenghts of times and found to be ~95%, 45%, 30% and 15% for samples of teeth, business cards, buttons and nails, respectively, following storage at room temperature in the dark for a period of 3 weeks after exposure. For samples stored under routine laboratory light, fading was much faster and the radiation-induced signals almost disappeared after a few hours of such illumination. It was concluded that the tested materials could be used in triage situations to detect and estimate the possible overexposure of individuals if the measurements can be performed soon enough after exposure.

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors.

PubMed

Karsch, L; Beyreuther, E; Burris-Mog, T; Kraft, S; Richter, C; Zeil, K; Pawelke, J

2012-05-01

The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10(11) Gy∕s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the number of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. The dosimeters are dose rate independent up to 4●10(9) Gy∕s within 2% (OSL and TLD) and up to 15●10(9) Gy∕s within 5% (EBT films). The diamond detectors show strong dose rate dependence. TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.

Dose rate dependence for different dosimeters and detectors: TLD, OSL, EBT films, and diamond detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karsch, L.; Beyreuther, E.; Burris-Mog, T.

Purpose: The use of laser accelerators in radiation therapy can perhaps increase the low number of proton and ion therapy facilities in some years due to the low investment costs and small size. The laser-based acceleration technology leads to a very high peak dose rate of about 10{sup 11} Gy/s. A first dosimetric task is the evaluation of dose rate dependence of clinical dosimeters and other detectors. Methods: The measurements were done at ELBE, a superconductive linear electron accelerator which generates electron pulses with 5 ps length at 20 MeV. The different dose rates are reached by adjusting the numbermore » of electrons in one beam pulse. Three clinical dosimeters (TLD, OSL, and EBT radiochromic films) were irradiated with four different dose rates and nearly the same dose. A faraday cup, an integrating current transformer, and an ionization chamber were used to control the particle flux on the dosimeters. Furthermore two diamond detectors were tested. Results: The dosimeters are dose rate independent up to 410{sup 9} Gy/s within 2% (OSL and TLD) and up to 1510{sup 9} Gy/s within 5% (EBT films). The diamond detectors show strong dose rate dependence. Conclusions: TLD, OSL dosimeters, and EBT films are suitable for pulsed beams with a very high pulse dose rate like laser accelerated particle beams.« less

Dating Saharan dust deposits on Lanzarote (Canary Islands) by luminescence dating techniques and their implication for palaeoclimate reconstruction of NW Africa

NASA Astrophysics Data System (ADS)

von Suchodoletz, H.; Fuchs, M.; ZöLler, L.

2008-02-01

Lava flow dammed valleys (Vegas) on Lanzarote (Canary Islands) represent unique sediment traps, filled with autochthonous volcanic material and allochthonous Saharan dust. These sediments and the intercalated palaeosoil sediments document past environmental change of the last glacial-interglacial cycles, both on Lanzarote and in NW Africa. A reliable chronology must be established to use these sediment archives for palaeoclimate reconstructions. Owing to the lack of organic material and the limiting time range of the 14C-dating method, luminescence dating is the most promising method for these sediments. However, the fluvio-eolian character of these sediments is a major problem for luminescence dating, because these sediments are prone to insufficient resetting of the parent luminescence signal (bleaching) prior to sedimentation. To check for the best age estimates, we compare the bleaching behavior of (1) different grain sizes (coarse- versus fine-grain quartz OSL) and (2) different minerals (fine-grain feldspar IRSL versus fine-grain quartz OSL). The results show that owing to its bleaching characteristics, quartz is the preferable mineral for luminescence dating. On the basis of the fine- and coarse-grain quartz OSL age estimates, a chronostratigraphy up to 100 ka could be established. Beyond this age limit for OSL quartz, the chronostratigraphy could be extended up to 180 ka by correlating the vega sediments with dated marine sediment archives.

Construction ages of the Upton Stone Chamber: Preliminary findings and suggestions for future luminescence research

USGS Publications Warehouse

Mahan, Shannon; Martin, Frederick; Taylor, Cathy

2015-01-01

The Upton Chamber in Massachusetts, an earth-covered stone structure 3.4 meters (m) in diameter, with a corbelled stone dome, and a 4.3 m long entrance passageway, is studied with the aim of determining whether optically stimulated luminescence (OSL) dating methods can be used to establish the approximate construction date of the entranceway. Three samples, taken from soil behind the lowest stones in the wall of the entrance passageway, returned OSL ages between 385 and 660 years ago (or from 1625 A.D. to 1350 A.D.; using the year 2011 as the 0 year). One sample, taken below the bottom of the artifact layers in an archeological test pit in front of the chamber entrance, returned OSL ages between 650 and 880 years ago. A modern sample collected from a nearby fluvial channel returned an age between 55 and 175 years. The Upton Chamber OSL sampling results are challenging to interpret because there are mixtures in the samples of both younger and older grains that likely result from human modification, root or soil processes, animal bioturbation (i.e. ants and worms), and/or partial bleaching. The ages were determined using the lowest component of the finite mixture model as applied to a distribution of quartz grains. Further research may enable us to determine whether older components are of anthropomorphic or geological origin.

Optically stimulated Al2O3:C luminescence dosimeters for teletherapy: Hp(10) performance evaluation.

PubMed

Hashim, S; Musa, Y; Ghoshal, S K; Ahmad, N E; Hashim, I H; Yusop, M; Bradley, D A; Kadir, A B A

2018-05-01

The performance of optically stimulated luminescence dosimeters (OSLDs, Al 2 O 3 :C) was evaluated in terms of the operational quantity of H P (10) in Co-60 external beam teletherapy unit. The reproducibility, signal depletion, and dose linearity of each dosimeter was investigated. For ten repeated readouts, each dosimeter exposed to 50mSv was found to be reproducible below 1.9 ± 3% from the mean value, indicating good reader stability. Meanwhile, an average signal reduction of 0.5% per readout was found. The dose response revealed a good linearity within the dose range of 5-50mSv having nearly perfect regression line with R 2 equals 0.9992. The accuracy of the measured doses were evaluated in terms of operational quantity H P (10), wherein the trumpet curve method was used respecting the 1990 International Commission on Radiological Protection (ICRP) standard. The accuracy of the overall measurements from all dosimeters was discerned to be within the trumpet curve and devoid of outlier. It is established that the achieved OSL Al 2 O 3 :C dosimeters are greatly reliable for equivalent dose assessment. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Si; Xu, Yuesheng, E-mail: yxu06@syr.edu; Zhang, Jiahan

Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work.more » Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean square errors (MSEs), and report the convergence speed and computation time. Results: HOTV-PAPA yields the best signal-to-noise ratio, followed by TV-PAPA and TV-OSL/GPF-EM. The local spatial resolution of HOTV-PAPA is somewhat worse than that of TV-PAPA and TV-OSL. Images reconstructed using HOTV-PAPA have the lowest local noise power spectrum (LNPS) amplitudes, followed by TV-PAPA, TV-OSL, and GPF-EM. The LNPS peak of GPF-EM is shifted toward higher spatial frequencies than those for the three other methods. The PAPA-type methods exhibit much lower ensemble noise, ensemble voxel variance, and image roughness. HOTV-PAPA performs best in these categories. Whereas images reconstructed using both TV-PAPA and TV-OSL are degraded by severe staircase artifacts; HOTV-PAPA substantially reduces such artifacts. It also converges faster than the other three methods and exhibits the lowest overall reconstruction error level, as measured by MSE. Conclusions: For high-noise simulated SPECT data, HOTV-PAPA outperforms TV-PAPA, GPF-EM, and TV-OSL in terms of hot lesion detectability, noise suppression, MSE, and computational efficiency. Unlike TV-PAPA and TV-OSL, HOTV-PAPA does not create sizable staircase artifacts. Moreover, HOTV-PAPA effectively suppresses noise, with only limited loss of local spatial resolution. Of the four methods, HOTV-PAPA shows the best lesion detectability, thanks to its superior noise suppression. HOTV-PAPA shows promise for clinically useful reconstructions of low-dose SPECT data.« less

Effective noise-suppressed and artifact-reduced reconstruction of SPECT data using a preconditioned alternating projection algorithm

PubMed Central

Li, Si; Zhang, Jiahan; Krol, Andrzej; Schmidtlein, C. Ross; Vogelsang, Levon; Shen, Lixin; Lipson, Edward; Feiglin, David; Xu, Yuesheng

2015-01-01

Purpose: The authors have recently developed a preconditioned alternating projection algorithm (PAPA) with total variation (TV) regularizer for solving the penalized-likelihood optimization model for single-photon emission computed tomography (SPECT) reconstruction. This algorithm belongs to a novel class of fixed-point proximity methods. The goal of this work is to investigate how PAPA performs while dealing with realistic noisy SPECT data, to compare its performance with more conventional methods, and to address issues with TV artifacts by proposing a novel form of the algorithm invoking high-order TV regularization, denoted as HOTV-PAPA, which has been explored and studied extensively in the present work. Methods: Using Monte Carlo methods, the authors simulate noisy SPECT data from two water cylinders; one contains lumpy “warm” background and “hot” lesions of various sizes with Gaussian activity distribution, and the other is a reference cylinder without hot lesions. The authors study the performance of HOTV-PAPA and compare it with PAPA using first-order TV regularization (TV-PAPA), the Panin–Zeng–Gullberg one-step-late method with TV regularization (TV-OSL), and an expectation–maximization algorithm with Gaussian postfilter (GPF-EM). The authors select penalty-weights (hyperparameters) by qualitatively balancing the trade-off between resolution and image noise separately for TV-PAPA and TV-OSL. However, the authors arrived at the same penalty-weight value for both of them. The authors set the first penalty-weight in HOTV-PAPA equal to the optimal penalty-weight found for TV-PAPA. The second penalty-weight needed for HOTV-PAPA is tuned by balancing resolution and the severity of staircase artifacts. The authors adjust the Gaussian postfilter to approximately match the local point spread function of GPF-EM and HOTV-PAPA. The authors examine hot lesion detectability, study local spatial resolution, analyze background noise properties, estimate mean square errors (MSEs), and report the convergence speed and computation time. Results: HOTV-PAPA yields the best signal-to-noise ratio, followed by TV-PAPA and TV-OSL/GPF-EM. The local spatial resolution of HOTV-PAPA is somewhat worse than that of TV-PAPA and TV-OSL. Images reconstructed using HOTV-PAPA have the lowest local noise power spectrum (LNPS) amplitudes, followed by TV-PAPA, TV-OSL, and GPF-EM. The LNPS peak of GPF-EM is shifted toward higher spatial frequencies than those for the three other methods. The PAPA-type methods exhibit much lower ensemble noise, ensemble voxel variance, and image roughness. HOTV-PAPA performs best in these categories. Whereas images reconstructed using both TV-PAPA and TV-OSL are degraded by severe staircase artifacts; HOTV-PAPA substantially reduces such artifacts. It also converges faster than the other three methods and exhibits the lowest overall reconstruction error level, as measured by MSE. Conclusions: For high-noise simulated SPECT data, HOTV-PAPA outperforms TV-PAPA, GPF-EM, and TV-OSL in terms of hot lesion detectability, noise suppression, MSE, and computational efficiency. Unlike TV-PAPA and TV-OSL, HOTV-PAPA does not create sizable staircase artifacts. Moreover, HOTV-PAPA effectively suppresses noise, with only limited loss of local spatial resolution. Of the four methods, HOTV-PAPA shows the best lesion detectability, thanks to its superior noise suppression. HOTV-PAPA shows promise for clinically useful reconstructions of low-dose SPECT data. PMID:26233214

Defining the upper age limit of luminescence dating: A case study using long lacustrine records from Chew Bahir, Ethiopia

NASA Astrophysics Data System (ADS)

Chapot, Melissa S.; Roberts, Helen M.; Lamb, Henry F.; Schäbitz, Frank; Asrat, Asfawossen; Trauth, Martin H.

2017-04-01

Optically stimulated luminescence (OSL) dating is a family of numerical chronometric techniques applied to quartz or feldspar mineral grains to assess the time since these grains were last exposed to sunlight (i.e. deposited), based on the amount of energy they absorbed from ambient radiation during burial. The maximum limit of any OSL dating technique is not defined by a fixed upper age limit, but instead by the maximum radiation dose the sample can accurately record before the OSL signal saturates. The challenge is to assess this upper limit of accurate age determination without necessitating comparison to independent age control. Laboratory saturation of OSL signals can be observed using a dose response curve (DRC) plotting OSL signal intensity against absorbed laboratory radiation dose. When a DRC is fitted with a single saturating exponential, one of the equation's parameters can be used to define a pragmatic upper limit beyond which uncertainties become large and asymmetric (Wintle and Murray, 2006). However, many sub-samples demonstrate DRCs that are best defined by double saturating exponential equations, which cannot be used to define this upper limit. To investigate the reliability of luminescence ages approaching saturation, Chapot et al. (2012) developed the Natural DRC concept, which uses expected ages derived from independent age control, combined with sample-specific measurements of ambient radioactivity, to calculate expected doses of absorbed radiation during burial. Natural OSL signal intensity is then plotted against these expected doses and compared to laboratory-generated DRCs. Using this approach, discrepancies between natural and laboratory DRCs have been observed for the same mineral material as natural OSL signal intensities saturate at absorbed radiation doses lower than the pragmatic upper limit defined by laboratory DRCs, leading to increasing age underestimation with depth without a metric for questioning the age reliability. The present study explores a means of defining the upper limit for reliable luminescence ages for sedimentary records without an established chronologic framework, using a long ( 280m; Cohen et al., 2016) lacustrine record from Chew Bahir, Ethiopia, drilled as part of the Hominin Sites and Paleolakes Drilling Project (HSPDP) of the International Continental Scientific Drilling Programme (ICDP) and CRC806 "Our way to Europe". Natural saturation of OSL signals is explored by plotting natural signal intensity against depth, creating a pseudo-Natural DRC that can be compared to laboratory DRCs. Unlike the homogenous deposits of the Chinese Loess Plateau where the Natural DRC concept was developed, the 280m composite core from Chew Bahir shows significant variation in lithology enabling investigation of the effects of sample to sample variability on Natural DRC construction, and facilitating comparison between signals from fine-quartz, fine-polymineral, and coarse-potassium feldspar grains. This work demonstrates how the concepts of Natural DRCs can be used to define the upper dating limit of sample suites without independent age control, providing valuable information for long sedimentary sequences such as the lacustrine deposits from Chew Bahir. Chapot M.S., et al. (2012), Radiation Measurements 47: 1045-1052. Cohen A, et al. (2016), Scientific Drilling 21: 1-16. Wintle, A.G., Murray, A.S. (2006) Radiation Measurements 41: 369-391.

Including Deposition Rate in Models of Cosmogenic Nuclide Accumulation in Fluvial Sediments to Improve Terrace Abandonment Ages

NASA Astrophysics Data System (ADS)

Norton, K. P.; Wang, N.; Van Dissen, R. J.; Little, T.

2017-12-01

Fluvial sediments are archives of the erosional, transport, and depositional processes occurring in the catchment. Terraces become robust markers for geomorphic analysis if their time of abandonment can be determined. Methods such as OSL can determine burial ages for fine grained sediments within the terrace fill but may not be directly related to the terrace abandonment age. Cosmogenic nuclides can be used to determine exposure ages for geologically young terraces but the surface being dated may have been subsequently eroded and the material itself may have been deposited with an inherited nuclide concentration. To deal with this problem, many researchers collect multiple samples with depth to model the depth-dependent nuclide concentration to help constrain inheritance and post-depositional erosion. It is often, however, assumed that the entire sediment pile accumulated instantaneously. In this submission, we present the results of a depth profile model that incorporates sediment accumulation rate to improve terrace age estimates. We test this model on fault-offset river terraces near Kaikoura, New Zealand. We measured depth profiles of OSL ages and cosmogenic nuclide concentrations of two late Quaternary terraces that are offset by up to 800 m across the Kekerengu Fault. OSL ages and dated tephras in the overlying loess provide minimum age constraints for both terraces while OSL ages of fine-grained sediments within the fill provide depositional ages. The predicted sedimentation rates for the terraces are as high as 0.5m/yr, consistent with geologically instantaneous deposition. Modelled abandonment ages from cosmogenic nuclides for the terraces are consistent with OSL and tephra constraints at 9.7 +/- 3.8 ka and 30.4 +/- 2.1 ka, respectively. These terrace abandonment ages yield dextral slip rates of 18.5-20.5 mm/yr and 25-28 mm/yr, respectively, consistent with the rapid slip rate on the adjacent Hope Fault.

Quartz and K-feldspar luminescence dating of sedimentation in the North Bohai coastal area (NE China) since the late pleistocene

NASA Astrophysics Data System (ADS)

Li, Yan; Shang, Zhiwen; Tsukamoto, Sumiko; Tamura, Toru; Yi, Liang; Wang, Hong; Frechen, Manfred; Li, Jianfen; Jiang, Xingyu

2018-02-01

In this study, luminescence dating of core sediments from the North Bohai Coast (China) was applied to provide a high-resolution chronological constraint, on a better understanding of the Holocene marine-terrestrial interaction. The studied sedimentary sequence contains a terrigenous deposit, a transgressive deposit and a prograding deltaic succession; all are believed to have formed during the late Pleistocene. To establish a reliable luminescence chronology, the luminescence signals of ten samples were investigated in order to quantify the degree of bleaching. This approach involved the use of quartz OSL, K-feldspar infrared stimulated luminescence (IRSL) and post-IR IRSL (pIRIR) ages. The resulting data were then compared with radiocarbon ages. The quartz OSL signals were well-bleached for all the samples, and the feldspar pIRIR150 and pIRIR225 signals yielded reliable ages for the pre-Holocene deposits but overestimated ages for late Holocene deposits (<1000 years). Radiocarbon data appeared to slightly overestimate the age of the young Holocene samples, therefore the chronological framework was established using quartz OSL ages. The early-mid Holocene transgressive deposits are relatively thin, which was attributed to the low-gradient relief and weak riverine fluvial input. Rapid deltaic progradation with high sedimentation rates over the last millennia, was revealed by the quartz OSL age results. This was supported by historical records for this section of the coastline. Episodic deposition around 700 years ago most likely triggered by frequent flooding events, was highlighted by the clustered OSL ages. While the sediment increment was 2.7 × 104 m3 a-1 for the period of ∼6-1 ka, this increased considerably to 9.1 × 106 m3 a-1 during the rapid progradation of the last millennium. The increase appears related to winter monsoon enhancement and human activity during the last 1000 years.

Experimental investigations of OSL signal changes of quartz gouge during low- to high-velocity friction

NASA Astrophysics Data System (ADS)

Oohashi, K.; Akasegawa, K.; Hasebe, N.; Miura, K.; Minomo, Y.

2017-12-01

Luminescence dating methods such as OSL and TL are mainly used to characterize an age of sediments based on trapping of electron by natural radiation exposure. Recent research suggests its potential applicability for direct age measurement of faulting. The idea behind to the luminescence dating for a determination of paleo-earthquake event is the accumulated natural radiation damage in intra-fault materials becomes to zero by the frictional heating and/or grinding. However, a relationship between fault motion and annihilation of luminescence signals, and its mechanism has not been understood. In this study, we conduct low- to high-velocity friction experiments using quartz gouge under various displacements and moisture conditions to establish an empirical relationship of OSL signal change upon shearing. In the friction experiments, we used quartz grains of <150 μm separated from the Cretaceous granite, taken from the east wall of the Nojima fault Ogura trench site, western Japan, as an analogue gouge. Our results of the OSL measurements are (1) <75 μm fraction of sheared gouge have high fast component ratio than the pre-sheared grains, (2) the fast component ratio of <75 μm fraction increases with increasing slip rate from 200 μm/s to 0.13 m, (3) OSL signal becomes to zero in the experiment sheared under 0.65 m/s. The increase of the fast component ratio found in relatively low slip-rate experiments may be caused by addition of ionized electrons, that emitted from newly formed fracture surface during comminution, in electron center. The signal zeroing observed in the high-velocity friction experiment is attributable to rapid frictional heating up to 700 °C estimated by temperature measurement and calculation. Based on the calculation of frictional energy we added to the experiment sheared under 0.65 m/s, we estimated the zeroing depth in natural conditions of earthquake (1.6 m in displacement) to 192 m.

SU-E-I-60: Validation of An Optically Stimulated Luminescent (OSL) Dosimeter for Use in Output Exposure Control Verification of Mammography Imaging Systems.

PubMed

Ranger, R; Butler, P; Yahnke, C; Valentino, D

2012-06-01

To develop and validate an Optically Stimulated Luminescent (OSL) dosimeter for exposure control verification of x-ray projection mammography imaging systems. The active detection element of the dosimeter is a strip of OSL material 3.0 mm wide, 0.13 mm thick and 30.0 mm long with an overlying aluminum step wedge with thicknesses of 0, 0.2, 0.4 and 0.6 mm Al, encapsulated in a light-tight plastic enclosure with outer dimensions of 10.0 mm wide, 5.4 mm thick, and 54.0 mm long. The dosimeter is used in conjunction with a breast phantom for the purpose of estimating the half-value layer (HVL), entrance surface exposure (ESE), and average glandular dose (AGD) in conventional projection mammography. ESE and HVL were computed based on analysis of exposure profiles obtained from exposed strip dosimeters. The AGD was estimated by multiplying the ESE by the appropriate exposure to dose conversion factor for the thickness and % glandular tissue fraction represented by the phantom and target-filter combination employed. The accuracy and reproducibility of the ESE, HVL and AGD estimates obtained using the dosimeter positioned on the surface of the ACR phantom at the chest wall edge, was evaluated using mammography systems utilizing different imaging receptor technology, i.e. screen-film (SF), computed radiography (CR) and direct radiography (DR) and compared against results obtained using a calibrated ion chamber fitted with a mammography probe. ESE, AGD and HVL results obtained using the OSL mammography QA dosimeter agreed with results obtained using an ion chamber to within 5-10%, depending on the target-filter combination used. Repeat readings were highly consistent with a coefficient of variation = 5%. The OSL mammography QA dosimeter has been shown to effectively estimate ESE, HVL and AGD, demonstrating its usefulness for secondary monitoring of output exposure of mammography imaging systems. © 2012 American Association of Physicists in Medicine.

OSL properties of three commonly available salt brands in India for its use in accident dosimetry

NASA Astrophysics Data System (ADS)

Singh, A. K.; Menon, S. N.; Kadam, S. Y.; Koul, D. K.; Datta, D.

2018-03-01

Thermally stimulated luminescence (TL) and Optically Stimulated Luminescence (OSL) characterization of three commonly available salt brands in India were undertaken for their application in accident dosimetry. The investigations showed that the luminescence properties differed to some extent with that reported in literature. Dosimetric properties of these salt samples showed that these can be useful in accident dosimetry. Based on the sensitization and fading behaviour of the samples a Single Aliquot Regenerative (SAR) protocol has been proposed for dose estimation.

Smartphone-based colorimetric ELISA implementation for determination of women's reproductive steroid hormone profiles.

PubMed

Ogirala, Tejaswi; Eapen, Ashley; Salvante, Katrina G; Rapaport, Tomas; Nepomnaschy, Pablo A; Parameswaran, Ash M

2017-10-01

Biologists frequently collect and analyze biospecimens in naturalistic (i.e., field) conditions to ascertain information regarding the physiological status of their study participants. Generally, field-collected biospecimens need to be stored frozen in the field and then transported frozen to laboratory facilities where traditional biomarker assays, such as enzyme-linked immunosorbent assays (ELISAs), are conducted. As proper storage and transport of frozen specimens is often logistically difficult and expensive, particularly in nonurban field settings, methods that reduce the need for specimen storage and transport would benefit field-research dependent disciplines such as biology, ecology and epidemiology. One limiting factor to running assays in the field is the use of large and expensive equipment to visualize and quantify the assays, such as microplate readers. Here, we describe an implementation of colorimetric ELISA visualization and quantification using two novel and portable imaging instrumentation systems and data processing techniques for the determination of women's reproductive steroid hormone profiles. Using the light absorbance and transmittance properties of the chemical compounds that make up the hormone assay, we were able to estimate unknown hormone concentrations using a smartphone system and a webcam system. These estimates were comparable to those from a standard laboratory multiple reader (smartphone: accuracy = 82.20%, R 2  > 0.910; webcam: accuracy = 87.59%, R 2  > 0.942). This line of applied research, in the long run, is expected to provide necessary information for examining the extent to which reproductive function varies within and between populations and how it is influenced by psychosocial, energetic and environmental challenges. Our validation of these novel, portable visualization and quantification systems allows for the eventual development of a compact and economical closed system which can be used to quantify biomarker concentrations in remote areas.

Developing OSL Geological Dating Techniques for Use on Future Missions to Mars

NASA Technical Reports Server (NTRS)

Blair, M. W.; Kalchgruber, R.; Deo, S.; McKeever, S. W. S.

2005-01-01

The surface of Mars has been subject to aeolian, fluvial, and periglacial activity in the (relatively) recent past. Unfortunately, chronological dating of recent events on Mars is difficult as the errors associated with crater counting are comparable to younger ages (approx. 1 Ma). Consequently, techniques to quantify the ages of geological processes on Mars have become an important area of research. Optically stimulated luminescence (OSL) dating is one candidate technique for in-situ dating of the deposition of Martian surface sediments. This method can aid in developing a geological and climatic history of the last million years on Mars. The current paper addresses some of the challenges and progress associated with developing OSL as a viable in-situ dating technique for Mars. Some of the challenges include the mineral composition, the effectiveness of solar resetting under Martian conditions, the temperature regime, and determining the natural dose rate on Mars. All of these topics are currently under investigation, and some preliminary results are presented.

Synthesis and luminescence properties of KSrPO{sub 4}:Eu{sup 2+} phosphor for radiation dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Palan, C. B., E-mail: chetanpalan27@yahoo.in; Bajaj, N. S.; Omanwar, S. K.

The KSrPO{sub 4}:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO{sub 4}:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO{sub 4}:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al{sub 2}O{sub 3}:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activationmore » energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.« less

Thermoluminescence and optically stimulated luminescence disadvantages of α-Al2O3:C crystal grown by the temperature gradient technique

NASA Astrophysics Data System (ADS)

Yang, Xin-Bo; Xu, Jun; Li, Hong-Jun; Bi, Qun-Yu; Cheng, Yan; Su, Liang-Bi; Tang, Qiang

2010-04-01

Recently, α-Al2O3:C crystal with highly sensitive thermoluminescence (TL) and optically stimulated luminescence (OSL) has been successfully grown by the temperature gradient technique. This paper investigates the heating rate dependence of TL sensitivity, light-induced fading of TL signals and thermal stability of OSL of α-Al2O3:C crystals. As the heating rate increases, the integral TL response decreases and the dosimetric glow peak shifts to higher temperatures in α-Al2O3:C crystals. Light-induced fading of TL increases with the irradiation dose, and TL response decreases as the exposure time increases, especially in the first 15 minutes. With the increasing intensity of the exposure light, the TL fading of α-Al2O3:C crystal increases sharply. The OSL response of as-grown α-Al2O3:C crystal is quite stable below 373 K and decreases sharply for higher temperatures.

Optically stimulated luminescence in an imaging plate using BaFi:Eu.

PubMed

Nanto, H; Araki, T; Daimon, M; Kusano, E; Kinbara, A; Kawabata, K; Nakano, Y

2002-01-01

BaFI:Eu phosphors are fabricated using a new method of synthesis: liquid phase synthesis, in which the phosphor particles are formed through the association of Ba2+ ions, F-ions and Eu2+ ions in solution. An intense optically stimulated luminescence (OSL) peak at about 410 nm is observed by stimulating X ray irradiated BaFI:Eu phosphor with about 550-750 nm light. It is found that the peak wavelength of the optically stimulation spectrum is about 690 nm. This result suggests that the semiconductor laser can be used as the stimulating light source. It is also found that the OSL intensity is increased with increasing the X ray dose. The BaFI:Eu phosphor as a photostimulable material for the imaging plate of a computed radiography system provides the following advantages; (1) high X ray absorption coefficient, (2) high monodispersion in size which would contribute to sharp images, (3) high OSL and thus low luminescence mottle and (4) high DQE (detective quantum efficiency).

The benefits of endurance exercise and Tai Chi Chuan for the task-switching aspect of executive function in older adults: an ERP study.

PubMed

Fong, Dong-Yang; Chi, Li-Kang; Li, Fuzhong; Chang, Yu-Kai

2014-01-01

This study was designed to determine the relationship between physical activity and the task-switching aspect of executive function by investigating the modulating roles of age, modality of physical activity, and type of cognitive function using behavioral and event-related potential (ERP) assessments. Sixty-four participants were assigned to one of four groups based on age and history of physical activity: older adults performing endurance exercise (OEE), older adults practicing Tai Chi Chuan (OTC), older adults with a sedentary lifestyle (OSL), and young adults (YA). Study participants completed a task-switching task under homogeneous and heterogeneous conditions while ERPs were recorded. The results revealed that YA had shortest reaction times compared with the three older adults groups, with OSL exhibiting the longest reaction time. YA also exhibited shorter P3 latency than OSL. No differences were observed in P3 amplitude between YA, OEE, and OTC; however, all three groups had significantly larger P3 amplitude compared with OSL in both task conditions. In conclusion, age and participation in physical activity influence the relationship between physical activity and task-switching, and a positive relationship was observed regardless of the modality of physical activity and type of cognitive function. Our ERP findings support the model of the scaffolding theory of aging and cognition (STAC) and suggest that regular participation in endurance exercise and Tai Chi Chuan may have equivalent beneficial effects on cognition at the behavioral and neuroelectric levels.

The benefits of endurance exercise and Tai Chi Chuan for the task-switching aspect of executive function in older adults: an ERP study

PubMed Central

Fong, Dong-Yang; Chi, Li-Kang; Li, Fuzhong; Chang, Yu-Kai

2014-01-01

This study was designed to determine the relationship between physical activity and the task-switching aspect of executive function by investigating the modulating roles of age, modality of physical activity, and type of cognitive function using behavioral and event-related potential (ERP) assessments. Sixty-four participants were assigned to one of four groups based on age and history of physical activity: older adults performing endurance exercise (OEE), older adults practicing Tai Chi Chuan (OTC), older adults with a sedentary lifestyle (OSL), and young adults (YA). Study participants completed a task-switching task under homogeneous and heterogeneous conditions while ERPs were recorded. The results revealed that YA had shortest reaction times compared with the three older adults groups, with OSL exhibiting the longest reaction time. YA also exhibited shorter P3 latency than OSL. No differences were observed in P3 amplitude between YA, OEE, and OTC; however, all three groups had significantly larger P3 amplitude compared with OSL in both task conditions. In conclusion, age and participation in physical activity influence the relationship between physical activity and task-switching, and a positive relationship was observed regardless of the modality of physical activity and type of cognitive function. Our ERP findings support the model of the scaffolding theory of aging and cognition (STAC) and suggest that regular participation in endurance exercise and Tai Chi Chuan may have equivalent beneficial effects on cognition at the behavioral and neuroelectric levels. PMID:25389403

Luminescence dating of anthropogenic features of the San Luis Valley, Colorado: from stone huts to stone walls

USGS Publications Warehouse

Mahan, Shannon; Donlan, Rebecca A.; Kardos, Barbara Maat

2015-01-01

The Snake Nest Wall site and the Crestone Stone Huts are in the northern San Luis Valley, Colorado, and provide a unique opportunity to date high-altitude archeological sites of unknown age and origin using optically stimulated luminescence (OSL). We sampled sediment underlying foundation stones of these structures to establish a chronological framework for each site's construction. OSL dating of the quartz grains directly under the Snake Nest Wall suggest that the stones and, therefore, the structure was most recently emplaced between 1855 and 1890 A.D. Dating of the sediment beneath the Crestone Stone Huts suggests the construction time of these huts is between 1860 and 1890 A.D. Analysis of the equivalent dose (DE) dispersion of the OSL samples at Snake Nest Wall and the Crestone Huts shows that the majority of sediments were fully bleached prior to deposition and the low scatter suggests that short-term or shallow alluvial processes were the dominant transport for sediments. In both cases, the OSL ages show that the construction was during very recent historical times, although it is likely that the Snake Nest Wall was rebuilt in the late 19th century. Further study is warranted at the Snake Nest Wall since it shows signs of greater antiquity and a continued presence of human use. The Crestone Huts are shown to be a product of railroad building during the boomtown days of Lucky and Crestone.

Bioactivity characterization of 45S5 bioglass using TL, OSL and EPR: Comparison with the case of 58S sol-gel bioactive glass.

PubMed

Polymeris, G S; Giannoulatou, V; Kyriakidou, A; Sfampa, I K; Theodorou, G S; Şahiner, E; Meriç, N; Kitis, G; Paraskevopoulos, K M

2017-01-01

The current work exploits the effective application of thermoluminescence (TL), optically stimulated luminescence (OSL) and the possibility of applying Electron Paramagnetic Resonance (EPR) for the discrimination between different bioactive responses in the case of the 45S5 bioactive glass (SiO 2 45, Na 2 O 24.5, CaO 24.5, P 2 O 5 6 in wt%), which was synthesized through melting process. These techniques are suggested mainly due to their low spectroscopic detection thresholds. The original 45S5 in grain size range of 20-40μm was immersed in the Simulated Body Fluid (SBF) for various different immersion times ranging over one week. In this work the 110°C TL peak, a specific OSL component and the EPR signal at g=2.013 ascribed to oxygen hole center (OHC) are used due to their sensitivity to the different bioactive responses. For all luminescence and EPR components, the intensity plot versus immersion time yields sharp discontinuities, resulting in effective probes regarding the timescale for both the beginning as well as the end of the procedure of the crystalline HCAp formation respectively. On the contrary to the smooth decreasing pattern of both luminescence entities, the peak to peak amplitude of the EPR signal indicates an initial increase for the initial 16min of immersion, followed by a further decrease throughout the immersion time duration. The discontinuities monitored for both sensitivity of TL, OSL and EPR, in conjunction with the discontinuities monitored for the sensitization of TL and OSL, when plotted versus immersion time, provide an individual time scale for each one of the chemical reactions involved in the five steps of the aforementioned procedure. According to the authors' best knowledge, scarce characterization techniques could provide this time scale frame, while it is the first time that such an application of OSL and EPR is attempted. Finally, the bioactive response of the 45S5 bioglass was compared with that of the 58S sol-gel bioactive glass, in terms of the timescale of these five stages required for the final formation of the HCAp. The techniques of luminescence and EPR which take advantage of trapped charges are proposed as alternative cheap and prompt effective techniques towards discrimination between different bioactive responses in bioactive glasses. Copyright © 2016. Published by Elsevier B.V.

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

PubMed Central

Zhang, Da; Li, Xinhua; Gao, Yiming; Xu, X. George; Liu, Bob

2013-01-01

Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues. Conclusions: The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols. PMID:23927332

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms.

PubMed

Zhang, Da; Li, Xinhua; Gao, Yiming; Xu, X George; Liu, Bob

2013-08-01

To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters "nanoDots" and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method--a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. A standard ATOM phantom has densely located holes (in 3×3 cm or 1.5×1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues. The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols.

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Da; Li, Xinhua; Liu, Bob

Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters “nanoDots” and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method—a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future.Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified themore » conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations.Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues.Conclusions: The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols.« less

Respiratory Motion-Resolved Compressed Sensing Reconstruction of Free-Breathing Radial Acquisition for Dynamic Liver Magnetic Resonance Imaging.

PubMed

Chandarana, Hersh; Feng, Li; Ream, Justin; Wang, Annie; Babb, James S; Block, Kai Tobias; Sodickson, Daniel K; Otazo, Ricardo

2015-11-01

This study aimed to demonstrate feasibility of free-breathing radial acquisition with respiratory motion-resolved compressed sensing reconstruction [extra-dimensional golden-angle radial sparse parallel imaging (XD-GRASP)] for multiphase dynamic gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced liver imaging, and to compare image quality to compressed sensing reconstruction with respiratory motion-averaging (GRASP) and prior conventional breath-held Cartesian-sampled data sets [BH volume interpolated breath-hold examination (VIBE)] in same patients. In this Health Insurance Portability and Accountability Act-compliant prospective study, 16 subjects underwent free-breathing continuous radial acquisition during Gd-EOB-DTPA injection and had prior BH-VIBE available. Acquired data were reconstructed using motion-averaging GRASP approach in which consecutive 84 spokes were grouped in each contrast-enhanced phase for a temporal resolution of approximately 14 seconds. Additionally, respiratory motion-resolved reconstruction was performed from the same k-space data by sorting each contrast-enhanced phase into multiple respiratory motion states using compressed sensing algorithm named XD-GRASP, which exploits sparsity along both the contrast-enhancement and respiratory-state dimensions.Contrast-enhanced dynamic multiphase XD-GRASP, GRASP, and BH-VIBE images were anonymized, pooled together in a random order, and presented to 2 board-certified radiologists for independent evaluation of image quality, with higher score indicating more optimal examination. The XD-GRASP reconstructions had significantly (all P < 0.05) higher overall image quality scores compared to GRASP for early arterial (reader 1: 4.3 ± 0.6 vs 3.31 ± 0.6; reader 2: 3.81 ± 0.8 vs 3.38 ± 0.9) and late arterial (reader 1: 4.5 ± 0.6 vs 3.63 ± 0.6; reader 2: 3.56 ± 0.5 vs 2.88 ± 0.7) phases of enhancement for both readers. The XD-GRASP also had higher overall image quality score in portal venous phase, which was significant for reader 1 (4.44 ± 0.5 vs 3.75 ± 0.8; P = 0.002). In addition, the XD-GRASP had higher overall image quality score compared to BH-VIBE for early (reader 1: 4.3 ± 0.6 vs 3.88 ± 0.6; reader 2: 3.81 ± 0.8 vs 3.50 ± 1.0) and late (reader 1: 4.5 ± 0.6 vs 3.44 ± 0.6; reader 2: 3.56 ± 0.5 vs 2.94 ± 0.9) arterial phases. Free-breathing motion-resolved XD-GRASP reconstructions provide diagnostic high-quality multiphase images in patients undergoing Gd-EOB-DTPA-enhanced liver examination.

AN ADVANCED CALIBRATION PROCEDURE FOR COMPLEX IMPEDANCE SPECTRUM MEASUREMENTS OF ADVANCED ENERGY STORAGE DEVICES

DOE Office of Scientific and Technical Information (OSTI.GOV)

William H. Morrison; Jon P. Christophersen; Patrick Bald

With the increasing demand for electric and hybrid electric vehicles and the explosion in popularity of mobile and portable electronic devices such as laptops, cell phones, e-readers, tablet computers and the like, reliance on portable energy storage devices such as batteries has likewise increased. The concern for the availability of critical systems in turn drives the availability of battery systems and thus the need for accurate battery health monitoring has become paramount. Over the past decade the Idaho National Laboratory (INL), Montana Tech of the University of Montana (Tech), and Qualtech Systems, Inc. (QSI) have been developing the Smart Batterymore » Status Monitor (SBSM), an integrated battery management system designed to monitor battery health, performance and degradation and use this knowledge for effective battery management and increased battery life. Key to the success of the SBSM is an in-situ impedance measurement system called the Impedance Measurement Box (IMB). One of the challenges encountered has been development of an accurate, simple, robust calibration process. This paper discusses the successful realization of this process.« less

Performance of optically stimulated luminescence Al₂O₃ dosimeter for low doses of diagnostic energy X-rays.

PubMed

Lim, Chang Seon; Lee, Sang Bock; Jin, Gye Hwan

2011-10-01

Personal dosimeters measure the radiation dose from exposure to hazardous sources outside the body. The present manuscript evaluates the performance of a commercially available optically stimulated luminescence (OSL) Al₂O₃ dosimeter using diagnostic energy X-rays. The OSL system satisfies the ANSI N13.11-2001 performance criteria for low dose diagnostic energy X-rays. Non-uniformity of sensitivity, dose linearity, X-ray energy response, and angular performance are all within the criteria of IEC-62387-1(2007). Copyright © 2011 Elsevier Ltd. All rights reserved.

A Rapid and Sensitive Strip-Based Quick Test for Nerve Agents Tabun, Sarin, and Soman Using BODIPY-Modified Silica Materials.

PubMed

Climent, Estela; Biyikal, Mustafa; Gawlitza, Kornelia; Dropa, Tomáš; Urban, Martin; Costero, Ana M; Martínez-Máñez, Ramón; Rurack, Knut

2016-08-01

Test strips that in combination with a portable fluorescence reader or digital camera can rapidly and selectively detect chemical warfare agents (CWAs) such as Tabun (GA), Sarin (GB), and Soman (GD) and their simulants in the gas phase have been developed. The strips contain spots of a hybrid indicator material consisting of a fluorescent BODIPY indicator covalently anchored into the channels of mesoporous SBA silica microparticles. The fluorescence quenching response allows the sensitive detection of CWAs in the μg m(-3) range in a few seconds. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

A Novel Intracranial Pressure Readout Circuit for Passive Wireless LC Sensor.

PubMed

Wang, Fa; Zhang, Xuan; Shokoueinejad, Mehdi; Iskandar, Bermans J; Medow, Joshua E; Webster, John G

2017-10-01

We present a wide frequency range, low cost, wireless intracranial pressure monitoring system, which includes an implantable passive sensor and an external reader. The passive sensor consists of two spiral coils and transduces the pressure change to a resonant frequency shift. The external portable reader reads out the sensor's resonant frequency over a wide frequency range (35 MHz-2.7 GHz). We propose a novel circuit topology, which tracks the system's impedance and phase change at a high frequency with low-cost components. This circuit is very simple and reliable. A prototype has been developed, and measurement results demonstrate that the device achieves a suitable measurement distance (>2 cm), sufficient sample frequency (>6 Hz), fine resolution, and good measurement accuracy for medical practice. Responsivity of this prototype is 0.92 MHz/mmHg and resolution is 0.028 mmHg. COMSOL specific absorption rate simulation proves that this system is safe. Considerations to improve the device performance have been discussed, which include the size of antenna, the power radiation, the Analog-to-digital converter (ADC) choice, and the signal processing algorithm.

The timing of sediment transport down Monterey Submarine Canyon, offshore California

USGS Publications Warehouse

Stevens, Thomas; Paull, Charles K.; Ussler, William III; McGann, Mary; Buylaert, Jan-Pieter; Lundsten, Eve M.

2013-01-01

While submarine canyons are the major conduits through which sediments are transported from the continents out into the deep sea, the time it takes for sediment to pass down through a submarine canyon system is poorly constrained. Here we report on the first study to couple optically stimulated luminescence (OSL) ages of quartz sand deposits and accelerator mass spectrometry 14C ages measured on benthic foraminifera to examine the timing of sediment transport through the axial channel of Monterey Submarine Canyon and Fan, offshore California. The OSL ages date the timing of sediment entry into the canyon head while the 14C ages of benthic foraminifera record the deposition of hemipelagic sediments that bound the sand horizons. We use both single-grain and small (∼2 mm area) single-aliquot regeneration approaches on vibracore samples from fining-upward sequences at various water depths to demonstrate relatively rapid, decadal-scale sand transport to at least 1.1 km depth and more variable decadal- to millennial-scale transport to a least 3.5 km depth on the fan. Significant differences between the time sand was last exposed at the canyon head (OSL age) and the timing of deposition of the sand (from 14C ages of benthic foraminifera in bracketing hemipelagic sediments) are interpreted as indicating that the sand does not pass through the entire canyon instantly in large individual events, but rather moves multiple times before emerging onto the fan. The increased spread in single-grain OSL dates with water depth provides evidence of mixing and temporary storage of sediment as it moves through the canyon system. The ages also indicate that the frequency of sediment transport events decreases with distance down the canyon channel system. The amalgamated sands near the canyon head yield OSL ages that are consistent with a sub-decadal recurrence frequency while the fining-upward sand sequences on the fan indicate that the channel is still experiencing events with a 150–250 year recurrence frequency out to 3.5 km water depths.    

Landform evolution modeling of fine-grained sedimentation on alluvial fans on Mars and Earth

NASA Astrophysics Data System (ADS)

Morgan, A. M.; Howard, A. D.; Moore, J. M.; Swander, Z. J.; Fink, D.; Korup, O.; Hesse, P. P.; Singh, T.; Srivastava, P.

2017-12-01

Reconstructing how rivers respond to changes in runoff or sediment supply by incising or aggrading has been pivotal in gauging the role of the Indian Summer Monsoon (ISM) as a geomorphic driver in the Himalayas. Here we present new data on how the fluvial systems of the Lesser Himalaya of India has responded to late Quaternary climate change. Our study is based on new chronological data for fluvial aggradation and incision from the Donga alluvial fan and several reaches of the upper Alaknanda River, as well as a meta-analysis of previous work. Fluvial sediments in the Himalayas in general, and quartz from the region in particular, have been previously noted for a number of unsuitable OSL properties including large recuperation and the existence of unremovable feldspar signals, leading to controversial discussions with regard to the reliability of existing OSL chronologies in this region. In order to improve the applicability and validity of OSL in the Lesser Himalaya, we have tested and applied pulsed OSL signals (POSL) to quartz grains from alluvial terrace and fan sediments, and propose a new chronology of regional fluvial aggradation. For previously dated terraces and alluvial fan sections, our POSL ages are systematically older than previously reported OSL ages. These results suggest periods of aggradation in the Alaknanda and Dehradun Valleys mainly between 20 and 50 ka. This most likely reflects decreased stream power during periods of weakened monsoon. The concentration of in-situ cosmogenic beryllium-10 from fluvial bedrock surfaces was also used to infer bedrock surface exposure ages, which should inform about episodes of active fluvial erosion. Resulting exposure ages span between 1.3 and 9.0 ka, suggesting that strath terraces were exposed relatively recently, and incision was dominant through most of the Holocene. In combination, our results support a precipitation-driven climatic control on fluvial dynamics, which regulates the balance between stream power and sediment supply. On a larger spatial scale, however, fluvial dynamics are probably not homogeneous as aggradation was taking place in adjacent catchments while incision dominated in the study area.

SU-D-304-06: Measurement of LET in Patient-Specific Proton Therapy Treatment Fields Using Optically Stimulated Luminescence Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Granville, DA; Sahoo, N; Sawakuchi, GO

Purpose: To investigate the use of optically stimulated luminescence (OSL) detectors (OSLDs) for measurements of dose-averaged linear energy transfer (LET) in patient-specific proton therapy treatment fields. Methods: We used Al{sub 2}O{sub 3}:C OSLDs made from the same material as commercially available nanoDot OSLDs from Landauer, Inc. We calibrated two parameters of the OSL signal as functions of LET in therapeutic proton beams: the ratio of the ultraviolet and blue emission intensities (UV/blue ratio) and the OSL curve shape. These calibration curves were created by irradiating OSLDs in passively scattered beams of known LET (0.96 to 3.91 keV/µm). The LET valuesmore » were determined using a validated Monte Carlo model of the beamline. We then irradiated new OSLDs with the prescription dose (16 to 74 cGy absorbed dose to water) at the center of the spread-out Bragg peak (SOBP) of four patient-specific treatment fields. From readouts of these OSLDs, we determined both the UV/blue ratio and OSL curve shape parameters. Combining these parameters with the calibration curves, we were able to measure LET using the OSLDs. The measurements were compared to the theoretical LET values obtained from Monte Carlo simulations of the patient-specific treatments fields. Results: Using the UV/blue ratio parameter, we were able to measure LET within 3.8%, 6.2%, 5.6% and 8.6% of the Monte Carlo value for each of the patient fields. Similarly, using the OSL curve shape parameter, LET measurements agreed within 0.5%, 11.0%, 2.5% and 7.6% for each of the four fields. Conclusion: We have demonstrated a method to verify LET in patient-specific proton therapy treatment fields using OSLDs. The possibility of enhancing biological effectiveness of proton therapy treatment plans by including LET in the optimization has been previously shown. The LET verification method we have demonstrated will be useful in the quality assurance of such LET optimized treatment plans. DA Granville received financial support from the Natural Sciences and Engineering Research Council of Canada.« less

A methodology for on‐board CBCT imaging dose using optically stimulated luminescence detectors

PubMed Central

Yusuf, Muhammad; Alothmany, Nazeeh; Kinsara, A. Abdulrahman; Abdulkhaliq, Fahad; Ghamdi, Suliman M.; Saoudi, Abdelhamid

2016-01-01

Cone‐beam computed tomography CBCT systems are used in radiation therapy for patient alignment and positioning. The CBCT imaging procedure for patient setup adds substantial radiation dose to patient's normal tissue. This study presents a complete procedure for the CBCT dosimetry using the InLight optically‐stimulated‐luminescence (OSL) nanoDots. We report five dose parameters: the mean slice dose (DMSD); the cone beam dose index (CBDIW); the mean volume dose (DMVD); point‐dose profile, D(FOV); and the off‐field Dose. In addition, CBCT skin doses for seven pelvic tumor patients are reported. CBCT‐dose measurement was performed on a custom‐made cylindrical acrylic body phantom (50 cm length, 32 cm diameter). We machined 25 circular disks (2 cm thick) with grooves and holes to hold OSL‐nanoDots. OSLs that showed similar sensitivities were selected and calibrated against a Farmer‐type ionization‐chamber (0.6 CT) before being inserted into the grooves and holes. For the phantom scan, a standard CBCT‐imaging protocol (pelvic sites: 125 kVp, 80 mA and 25 ms) was used. Five dose parameters were quantified: DMSD, CBDIW, DMVD, D(FOV), and the off‐field dose. The DMSD for the central slice was 31.1±0.85 mGy, and CBDIW was 34.5±0.6 mGy at 16 cm FOV. The DMVD was 25.6±1.1 mGy. The off‐field dose was 10.5 mGy. For patients, the anterior and lateral skin doses attributable to CBCT imaging were 39.04±4.4 and 27.1±1.3 mGy, respectively. OSL nanoDots were convenient to use in measuring CBCT dose. The method of selecting the nanoDots greatly reduced uncertainty in the OSL measurements. Our detailed calibration procedure and CBCT dose measurements and calculations could prove useful in developing OSL routines for CBCT quality assessment, which in turn gives them the property of high spatial resolution, meaning that they have the potential for measurement of dose in regions of severe dose‐gradients. PACS number(s): 87.57.‐s, 87.57.Q, 87.57.uq PMID:27685143

Effects of nanostructuring on luminescence properties of SrS:Ce,Sm phosphor: An experimental and phenomenological study

NASA Astrophysics Data System (ADS)

Yazdanmehr, Mohsen; Sadeghi, Hossein; Tehrani, Masoud Kavosh; Hashemifar, Seyed Javad; Mahdavi, Mohammad

2018-01-01

In this work, we employ various experimental techniques to illustrate the effects of nanostructuring on improvement of the luminescence properties of the polycrystalline SrS co-activated by cerium and samarium dopants (SrS : Ce , Sm). The nano and microstructure SrS : Ce , Sm powders were synthesized by the co-precipitation and solid state diffusion methods, respectively, followed by the spark plasma sintering (SPS) process to densify powders into pellet shape. It is observed that the photo-luminescence (PL), radio-luminescence (RL), and optically stimulated luminescence (OSL) emission intensity of the nanostructure samples are significantly improved with respect to the microstructure samples. Moreover, by using an accurate photomultiplier tube, we measured the CW-OSL decay curves of the samples to demonstrate much higher and faster sensitivity of the nanostructure SrS : Ce , Sm for in-flight and online OSL radiation dosimetry. The obtained absorption and emission spectra are used for phenomenology of the electronic band structure of the SrS : Ce , Sm micro and nano-phosphors inside the band gap. The proposed phenomenological electronic structures are then used to clarify the role of Ce3+ and Sm3+ localized energy levels in the luminescence properties of the nano and microstructure samples. It is argued that electronic transitions from the 2T2g state of Ce3+ and the 4G5/2 state of Sm3+ have strong contribution to the PL and RL emission spectra, while in the OSL mechanism, the Sm3+ 4G5/2 state is mainly responsible for electrons trapping.

Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

PubMed

Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

2016-01-01

For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region.

Luminescence of quartz and feldspar fingerprints provenance and correlates with the source area denudation in the Amazon River basin

NASA Astrophysics Data System (ADS)

Sawakuchi, A. O.; Jain, M.; Mineli, T. D.; Nogueira, L.; Bertassoli, D. J.; Häggi, C.; Sawakuchi, H. O.; Pupim, F. N.; Grohmann, C. H.; Chiessi, C. M.; Zabel, M.; Mulitza, S.; Mazoca, C. E. M.; Cunha, D. F.

2018-06-01

The Amazon region hosts the world's largest watershed spanning from high elevation Andean terrains to lowland cratonic shield areas in tropical South America. This study explores variations in optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) signals in suspended silt and riverbed sands retrieved from major Amazon rivers. These rivers drain Pre-Cambrian to Cenozoic source rocks in areas with contrasting denudation rates. In contrast to the previous studies, we do not observe an increase in the OSL sensitivity of quartz with transport distance; for example, Tapajós and Xingu Rivers show more sensitive quartz than Solimões and Madeira Rivers, even though the latter have a significantly larger catchment area and longer sediment transport distance. Interestingly, high sensitivity quartz is observed in rivers draining relatively stable Central Brazil and Guiana shield areas (denudation rate ξ = 0.04 mmyr-1), while low sensitivity quartz occurs in less stable Andean terrains (ξ = 0.24 mmyr-1). An apparent linear correlation between quartz OSL sensitivity and denudation rate suggests that OSL sensitivity may be used as a proxy for erosion rates in the Amazon basin. Furthermore, luminescence sensitivity measured in sand or silt arises from the same mineral components (quartz and feldspar) and clearly discriminates between Andean and shield sediments, avoiding the grain size bias in provenance analysis. These results have implications for using luminescence sensitivity as a proxy for Andean and shield contributions in the stratigraphic record, providing a new tool to reconstruct past drainage configurations within the Amazon basin.

Photon energy dependence of three fortuitous dosemeters from personal electronic devices, measured by optically stimulated luminescence.

PubMed

Beerten, Koen; Vanhavere, Filip

2010-08-01

New data are presented with regard to the relative OSL sensitivity of three different emergency dosemeters irradiated to various photon energies approximately between 48 and 1250 keV using blue excitation light. Investigated components extracted from commonly worn objects include those from USB flash drives (alumina substrate), mobile phones (Ba-rich silicate) and credit cards (chip card module). Several basic properties have been investigated such as the overall radiation sensitivity, the shape of the decay curve and fading of the OSL signal. An increase of the sensitivity for low energies relative to (60)Co gamma rays can be observed for the three dosemeters, the increase being very pronounced for the Ba-rich component (factor of 10) and less pronounced for the chip card module (factor of 2). It is concluded that proper dose correction factors for photon energy have to be applied in order to accurately determine the absorbed dose to tissue. The OSL sensitivity to neutron irradiation was investigated as well, but this was found to be less than the gamma sensitivity.

Abrupt sand-dune accumulation at the northeastern margin of the Tibetan Plateau challenges the wet MIS3a inferred from numerous lake-highstands

PubMed Central

Long, Hao; Fuchs, Markus; Yang, Linhai; Cheng, Hongyi

2016-01-01

Over the Tibetan Plateau and adjacent regions, numerous 14C-based lake records revealed a ubiquitous wet climatic period during 40–25 ka (late MIS 3), which is in contradiction with the global pattern of generally cold and dry climates. This paper focuses on OSL dating results of a large set of sand dunes and alluvial sediments (50 OSL ages) from the Qinwangchuan (QWC) Basin at the northeast edge of the Tibetan Plateau, with the aim to test the validity of the anomalous wet condition for the late MIS 3 interval, evidenced by numerous lake highstands. The abrupt sand dune accumulation as indication of increased aridity in the study area was OSL dated to ~40–13 ka. This dry climatic inference of the sand dune system from QWC apparently shows no wet MIS 3a event. Thus, the anomalous wet conditions revealed by high lake levels for the late MIS 3 phase may not be a universal phenomena across entire western China. PMID:27172907

Sol-gel derived copper-doped silica glass as a sensitive material for X-ray beam dosimetry

NASA Astrophysics Data System (ADS)

Capoen, Bruno; Hamzaoui, Hicham El; Bouazaoui, Mohamed; Ouerdane, Youcef; Boukenter, Aziz; Girard, Sylvain; Marcandella, Claude; Duhamel, Olivier

2016-01-01

The light emission from a sol-gel-derived Cu-doped silica glass was studied under 10 keV X-ray irradiation using a fibered setup. Both radioluminescence (RL) and optically stimulated luminescence (OSL) were analyzed at different high dose rates up to 50 Gy/s and for different exposure times, yielding accumulated doses up to 50 kGy (in SiO2). Even if a darkening effect appears at this dose level, the material remains X-sensitive after exposure to several kGy. At low dose rate, the scintillation mechanisms are similar to photoluminescence, involving the Cu+ ions electronic levels, contrary to the nonlinear domain (for dose rates higher than 30 Gy/s). This RL, as well as the OSL, could be exploited in their linear domain to measure doses as high as 3 kGy. A thorough study of the OSL signal has shown that it must be employed with caution in order to take the fading phenomenon and the response dependency on stimulation source intensity into consideration.

Energy absorption buildup factors, exposure buildup factors and Kerma for optically stimulated luminescence materials and their tissue equivalence for radiation dosimetry

NASA Astrophysics Data System (ADS)

Singh, Vishwanath P.; Badiger, N. M.

2014-11-01

Optically stimulated luminescence (OSL) materials are sensitive dosimetric materials used for precise and accurate dose measurement for low-energy ionizing radiation. Low dose measurement capability with improved sensitivity makes these dosimeters very useful for diagnostic imaging, personnel monitoring and environmental radiation dosimetry. Gamma ray energy absorption buildup factors and exposure build factors were computed for OSL materials using the five-parameter Geometric Progression (G-P) fitting method in the energy range 0.015-15 MeV for penetration depths up to 40 mean free path. The computed energy absorption buildup factor and exposure buildup factor values were studied as a function of penetration depth and incident photon energy. Effective atomic numbers and Kerma relative to air of the selected OSL materials and tissue equivalence were computed and compared with that of water, PMMA and ICRU standard tissues. The buildup factors and kerma relative to air were found dependent upon effective atomic numbers. Buildup factors determined in the present work should be useful in radiation dosimetry, medical diagnostics and therapy, space dosimetry, accident dosimetry and personnel monitoring.

TL-OSL study of Li{sub 3}PO{sub 4}: Mg, Cu phosphor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rahangdale, S. R., E-mail: sachin.rahangdale1@gmail.com; Wankhede, S. P.; Dhabekar, B. S.

In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li{sub 3}PO{sub 4} phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li{sub 3}PO{sub 4} shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

Measurement of the distribution of radiation in the area surrounding the target mass using optically stimulated luminescence technique.

PubMed

Tanır, A Güneş; Yedek, Hatice; Koç, Kemal; Bölükdemir, M Hicabi

2017-01-01

The scattered doses received by the area surrounding the target that has been subjected to x-rays were investigated. Two experiments were carried out: 1- Al 2 O 3 : C was used as dosimeter and the luminescence counts was measured using both the RisØ TL/OSL system and an ion chamber. 2- BeO aliquots were used and the counts were read using the IBEOX/OSL system. According to the results, the doses absorbed by the area surrounding the target are significantly amount. Copyright © 2016 Elsevier Ltd. All rights reserved.

TL-OSL study of Li3PO4: Mg, Cu phosphor

NASA Astrophysics Data System (ADS)

Rahangdale, S. R.; Wankhede, S. P.; Dhabekar, B. S.; Palikundwar, U. A.; Moharil, S. V.

2015-08-01

In the present work, we report the thermoluminescence and optically stimulated luminescence properties of Mg and Cu doped Li3PO4 phosphor. The phosphor was synthesized by precipitation method. The thermoluminescence dosimetric peak temperature for the phosphor varies with concentrations of Mg and Cu. Li3PO4 shows good response to 470nm optical stimulation. The OSL sensitivity of the phosphor is approximately 12 times than that of standard Lithium magnesium phosphate. This study may help to develop this material for the application in real time dosimetry using optically stimulated luminescence.

OSL and pollen concentrate 14C dating of dammed lake sediments at Maoxian, east Tibet, and implications for two historical earthquakes in AD 638 and 952

NASA Astrophysics Data System (ADS)

Xu, H.; Jiang, H.; Yu, S.; Yang, H.; Chen, J.

2016-12-01

Formation of dammed lakes provides exceptionally important information of continental geological processes, responding to tectonic and climatic influences. Establishing accurate geochronological frameworks within lake strata is challenging because the stratigraphy is often bereft of biostratigraphy and directly dateable material. Optically Stimulated Luminescence (OSL) and AMS 14C dating of pollen concentrates are well-established tools for dating lake sediments. Whether they are suitable for lake sediments in high-alpine settings remains uncertain. In this study, OSL and AMS 14C dating of pollen concentrate were conducted on the Diaolin section in a high-alpine setting in the eastern Tibetan Plateau. Good match of both dating results suggests that they are fit for dating lake sediments in high alpine settings. More than 300 g of sediment is required for preparation of pollen concentrates. During the pretreatment, 3% NaOH solution should be added to the sample, and then heated until just boiling ( 5 min) because NaOH treatment easily destroys pollen grains. Applying the heavy liquid flotation with specific gravity of 1.74-1.76 is useful to isolate relatively pure pollen grains. Sieving with a 20-μm and 63-μm mesh can concentrate pollen grains substantially. The OSL and AMS 14C dating yielded the basal age of the Diaolin section (650 AD). This indicates that the dammed-lake formed around 650 AD, probably caused by the earthquake occurring in the study area in 638 AD. The seismites characterized by soft-sediment deformation and phyllite layer happened at 780-980 AD, probably corresponding to the earthquake occurring on November 20, 952 AD in the study area.

Evaluation of Al2O3:C optically stimulated luminescence (OSL) dosimeters for passive dosimetry of high-energy photon and electron beams in radiotherapy.

PubMed

Yukihara, E G; Mardirossian, G; Mirzasadeghi, M; Guduru, S; Ahmad, S

2008-01-01

This article investigates the performance of Al2O3: C optically stimulated luminescence dosimeters (OSLDs) for application in radiotherapy. Central-axis depth dose curves and optically stimulated luminescence (OSL) responses were obtained in a water phantom for 6 and 18 MV photons, and for 6, 9, 12, 16, and 20 MeV electron beams from a Varian 21EX linear accelerator. Single OSL measurements could be repeated with a precision of 0.7% (one standard deviation) and the differences between absorbed doses measured with OSLDs and an ionization chamber were within +/- 1% for photon beams. Similar results were obtained for electron beams in the low-gradient region after correction for a 1.9% photon-to-electron bias. The distance-to-agreement values were of the order of 0.5-1.0 mm for electrons in high dose gradient regions. Additional investigations also demonstrated that the OSL response dependence on dose rate, field size, and irradiation temperature is less than 1% in the conditions of the present study. Regarding the beam energy/quality dependence, the relative response of the OSLD for 18 MV was (0.51 +/- 0.48)% of the response for the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam was in average 1.9% higher, but this result requires further confirmation. The relative response did not seem to vary with electron energy at dmax within the experimental uncertainties (0.5% in average) and, therefore, a fixed correction factor of 1.9% eliminated the energy dependence in our experimental conditions.

Evaluation of Al{sub 2}O{sub 3}:C optically stimulated luminescence (OSL) dosimeters for passive dosimetry of high-energy photon and electron beams in radiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yukihara, E. G.; Mardirossian, G.; Mirzasadeghi, M.

This article investigates the performance of Al{sub 2}O{sub 3}:C optically stimulated luminescence dosimeters (OSLDs) for application in radiotherapy. Central-axis depth dose curves and optically stimulated luminescence (OSL) responses were obtained in a water phantom for 6 and 18 MV photons, and for 6, 9, 12, 16, and 20 MeV electron beams from a Varian 21EX linear accelerator. Single OSL measurements could be repeated with a precision of 0.7% (one standard deviation) and the differences between absorbed doses measured with OSLDs and an ionization chamber were within {+-}1% for photon beams. Similar results were obtained for electron beams in the low-gradientmore » region after correction for a 1.9% photon-to-electron bias. The distance-to-agreement values were of the order of 0.5-1.0 mm for electrons in high dose gradient regions. Additional investigations also demonstrated that the OSL response dependence on dose rate, field size, and irradiation temperature is less than 1% in the conditions of the present study. Regarding the beam energy/quality dependence, the relative response of the OSLD for 18 MV was (0.51{+-}0.48)% of the response for the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam. The OSLD response for the electron beams relative to the 6 MV photon beam was in average 1.9% higher, but this result requires further confirmation. The relative response did not seem to vary with electron energy at d{sub max} within the experimental uncertainties (0.5% in average) and, therefore, a fixed correction factor of 1.9% eliminated the energy dependence in our experimental conditions.« less

Geochronological (OSL) and geomorphological investigations at the presumed Frankfurt ice marginal position in northeast Germany

NASA Astrophysics Data System (ADS)

Hardt, Jacob; Lüthgens, Christopher; Hebenstreit, Robert; Böse, Margot

2016-12-01

The Weichselian Frankfurt ice marginal position in northeast Germany has been critically discussed in the past owing to weak morphological evidence and a lack of clear sedimentological records. This study aims to contribute to this discussion with new geochronological and geomorphological results. Apart from very few cosmogenic exposure ages, the time frame is to date still based on long distance correlation with radiocarbon chronologies. We selected a study site in a key position regarding the classic location of the Frankfurt ice marginal position and the recently described arcuate ridge structures on the Barnim plateau. For the first time we present Optically Stimulated Luminescence (OSL) ages of quartz from glaciofluvial deposits for this Weichselian phase. Our results indicate an advance of the Scandinavian Ice Sheet (SIS) at around 34.1 ± 4.6 ka. This is in agreement with OSL ages from sandur deposits at the Brandenburg ice marginal position located farther south and could also be correlated with the Klintholm advance in Denmark. The subsequent meltdown phase lasted until around 26.3 ± 3.7 ka. During the meltdown phase a minor oscillation of the SIS caused the formation of the recently described arcuate ridges on the Barnim till plain. Recalculated surface exposure ages of glacigenic boulders with an updated global production rate indicate a landscape stabilization phase at around 22.7 ± 1.6 ka, which is in agreement with our ages. A phase of strong aeolian activity has been dated with OSL to 1 ± 0.1 ka; this may have been triggered by human activities that are documented in this region for the medieval period.

Southern Salish Sea Habitat Map Series: Admiralty Inlet

USGS Publications Warehouse

Cochrane, Guy R.; Dethier, Megan N.; Hodson, Timothy O.; Kull, Kristine K.; Golden, Nadine E.; Ritchie, Andrew C.; Moegling, Crescent; Pacunski, Robert E.; Cochrane, Guy R.

2015-01-01

This publication includes four map sheets, explanatory text, and a descriptive pamphlet. Each map sheet is published as a portable document format (PDF) file. ESRI ArcGIS compatible geotiffs (for example, bathymetry) and shapefiles (for example video observation points) will be available for download in the data catalog associated with this publication (Cochrane, 2015). An ArcGIS Project File with the symbology used to generate the map sheets is also provided. For those who do not own the full suite of ESRI GIS and mapping software, the data can be read using ESRI ArcReader, a free viewer that is available at http://www.esri.com/software/arcgis/arcreader/index.html.

Sensors Applications, Volume 3, Sensors in Medicine and Health Care

NASA Astrophysics Data System (ADS)

Öberg, P. Åke; Togawa, Tatsuo; Spelman, Francis A.

2004-08-01

Taken as a whole, this series covers all major fields of application for commercial sensors, as well as their manufacturing techniques and major types. As such the series does not treat bulk sensors, but rather places strong emphasis on microsensors, microsystems and integrated electronic sensor packages. Each of the individual volumes is tailored to the needs and queries of readers from the relevant branch of industry. A review of applications for point-of-care diagnostics, their integration into portable systems and the comfortable, easy-to-use sensors that allow patients to monitor themselves at home. The book covers such advanced topics as minimal invasive surgery, implantable sensors and prostheses, as well as biocompatible sensing.

Development of a luminescence planetary surface dating instrument

NASA Astrophysics Data System (ADS)

Jain, M.; Lapp, T.; Andersen, M. T.; Hannemann, S.; Murray, A. S.; Duller, G. A. T.; Merrrisen, J.

2012-04-01

Luminescence dating (LD) is uniquely positioned for absolute, in-situ, dating of recent (< 1Ma) events on Mars such as the formation of sedimentary landforms, volcanic rocks and salt precipitates. These data can in turn help understand and predict the impact of climate-driven changes on Mars, for example, atmosphere-land interactions, global sand and dust movements and redistribution of volatiles (H2O and CO2). This understanding is critical for any manned mission to Mars and for our understanding of the planetary surface evolution. Despite this potential, the technology transfer from terrestrial to in-situ Martian dating is not trivial. Here we first provide a brief overview of the scientific issues involved in luminescence dating on Mars (e.g. dosimetric characteristics of Martian materials and modelling of cosmic-ray dose rate) and then the technical constraints on an instrument design appropriate for remotely-programmable mobile use on the Martian surface. The challenge is to develop a miniaturised portable luminescence reader that is as sensitive as a laboratory-based instrument and at the same time has sufficient flexibility for fully automated performance. Such an instrument could provide stratigraphic ages if deployed on a rover with a sub-surface drilling capability, or provide a survey of surface chronologies over extensive areas. To this end we have designed and manufactured an 'elegant breadboard' Planetary Surface Dating Instrument (PSDI) in a project supported by ESA. The PSDI is light weight and compact (~1 kg, ~1.4 litres) and has 3 different reloadable sample positions which can be rotated to sit under 3 different optical subunits or an x-ray irradiator. The optical subunits consists of three different detection channels (one red and two UV/blue) each based on a miniature photomultiplier tube, and three types of laser light stimulation sources (two 915 nm, one 530 nm and one 405 nm) that can be operated in continuous-wave or pulsed mode. The samples can be heated using an innovative heating concept where the sample disc (aluminium) absorbs energy from an IR laser below and a thermopile detector ensures the temperature control. The samples can thus be heated in a controlled manner to ~300°C for thermoluminescence (TL) or to ~250°C for elevated temperature optically stimulated luminescence (OSL) measurements. Calibration doses are given by a miniature X-ray tube, although to reduce power consumption the irradiator may be replaced by an unshielded beta source in a flight model. There is an artificial phosphor chip fixed to the rotating plate for checks on 'in situ' performance, calibration or surface dose-rate measurements. The rotation of the samples is automatically controlled to ensure correct positioning for dose measurements, and for sample loading or unloading. The luminescence signals can be measured in 3D time-resolved mode; these signals give information on mineralogy as well as age. The PSDI has been tested thoroughly and the results show a standard deviation of 1-2% for repeated measurements using different optical schemes. In terms of measurements of Martian analogue basalt samples, the sensitivity of the PSDI is better than the standard laboratory reader that weighs ~80 kg. Moreover, the PSDI has a greater number of measurement schemes which can all be programmed and run remotely. This combination offers the flexibility required to date deposits of previously unknown luminescence/dosimetric characteristics. We conclude that this instrument is a very promising candidate for a future Mars mission.

Properties of lithium aluminate for application as an OSL dosimeter

NASA Astrophysics Data System (ADS)

Twardak, A.; Bilski, P.; Marczewska, B.; Lee, J. I.; Kim, J. L.; Gieszczyk, W.; Mrozik, A.; Sądel, M.; Wróbel, D.

2014-11-01

Several samples of undoped and carbon or copper doped lithium aluminate (LiAlO2) were prepared in an attempt to achieve a material, which can be applicable in optically stimulated luminescence (OSL) dosimetry. All investigated samples are highly sensitive to ionizing radiation and show good reproducibility. The undoped and copper doped samples exhibit sensitivity several times higher than that of Al2O3:C, while sensitivity of the carbon doped samples is lower. The studied samples exhibit significant fading, but dynamics of signal loss is different for differently doped samples, what indicates a possibility of improving this characteristic by optimizing dopant composition.

Thermally and optically stimulated radiative processes in Eu and Y co-doped LiCaAlF6 crystal

NASA Astrophysics Data System (ADS)

Fukuda, Kentaro; Yanagida, Takayuki; Fujimoto, Yutaka

2015-06-01

Yttrium co-doping was attempted to enhance dosimeter performance of Eu doped LiCaAlF6 crystal. Eu doped and Eu, Y co-doped LiCaAlF6 were prepared by the micro-pulling-down technique, and their dosimeter characteristics such as optically stimulated luminescence (OSL) and thermally stimulated luminescence (TSL) were investigated. By yttrium co-doping, emission intensities of OSL and TSL were enhanced by some orders of magnitude. In contrast, scintillation characteristics of yttrium co-doped crystal such as intensity of prompt luminescence induced by X-ray and light yield under neutron irradiation were degraded.

Investigation of OSL signal of resistors from mobile phones for accidental dosimetry

NASA Astrophysics Data System (ADS)

Mrozik, A.; Marczewska, B.; Bilski, P.; Gieszczyk, W.

2014-12-01

Resistors from mobile phones, usually located near the human body, are considered as individual dosimeters of ionizing radiation in emergency situations. The resistors contain Al2O3, which is optically stimulated luminescence (OSL) material sensitive to ionizing radiation. This work is focused on determination of dose homogeneity within a mobile phones which was carried out by OSL measurements of resistors placed in different parts inside the mobile phone. Separate, commercially available resistors, similar in the shape and size to the resistors from circuit board of the studied mobile phone, were situated in different locations inside it. The irradiations were performed in uniform 60Co and 137Cs radiation fields, with the mobile phones connected and not connected to the cellular network. The dose decrease of 9% was measured for original resistors situated between layer of copper-clad laminate and battery, in comparison to the dose at the front of the phone. The resistors showed the lower signal when the mobile phone was connected to the cellular network, due to higher temperature inside the housing. The profile of fading was investigated within 3 month period for resistors irradiated with 1 Gy of gamma rays to estimate of the fading coefficient.

SU-E-T-264: Preliminary Results On New Optically Stimulated Luminescent Materials for Proton Therapy Dosimetry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Doull, B; Zheng, Y; Procure Proton Therapy Center, Oklahoma City, OK

2014-06-01

Purpose: The objective of this work is to test the premise that luminescence materials with less under-response to proton beams can be identified by testing their dose response to low-LET radiation. The goal is to develop new Optically Stimulated Luminescence (OSL) materials with improved response for proton therapy dosimetry. Methods: We first measured the dose response of new OSL materials, synthesized in our laboratory, to low-LET radiation (beta rays from a {sup 90}Sr/{sup 90}Y source) and selected two materials having different OSL saturation characteristics and good dosimetric properties, namely MgB4O7:Ce,Li and MgO:Li. Commercial Al2O3:C was also used for comparison. Thesemore » materials were then irradiated at several depths along a pristine proton beam. The luminescence responses of the materials, relative to the entrance response, were compared with the depth dose profile measured by a multiple-layer ion chamber. Results: The OSL signals of MgB4O7:Ce,Li and MgO:Li were characterized for signal stability, dose response, and response to a clinical proton beam. The materials were also compared with the commercial Al2O3:C. The signals from both MgB4O7:Ce,Li and MgO:Li were relatively stable after a one day delay following irradiation. The low-LET dose response of the materials showed that, over the dose range investigated (up to ∼800 Gy), MgB4O7:Ce,Li did not saturate, whereas MgO:Li and Al2O3:C saturated at doses of ∼100 Gy. MgB4O7:Ce,Li showed less underresponse to proton beams than MgO:Li and Al2O3:C. Conclusion: In general the material with the highest saturation doses for low-LET radiation (MgB4O7:Ce,Li) showed the least under-response to proton beams, which suggests that it may be possible to develop better OSL materials for proton dosimetry if the dose response can be controlled during synthesis. Nevertheless, the degree in which the response to proton beams can be controlled remains to be determined. The research is funded by the Oklahoma Center for the Advancement of Science and Technology (OCAST), project number HR12-055.« less

Clinical comparison of CR and screen film for imaging the critically ill neonate

NASA Astrophysics Data System (ADS)

Andriole, Katherine P.; Brasch, Robert C.; Gooding, Charles A.; Gould, Robert G.; Cohen, Pierre A.; Rencken, Ingo R.; Huang, H. K.

1996-05-01

A clinical comparison of computed radiography (CR) versus screen-film for imaging the critically-ill neonate is performed, utilizing a modified (hybrid) film cassette containing a CR (standard ST-V) imaging plate, a conventional screen and film, allowing simultaneous acquisition of perfectly matched CR and plain film images. For 100 portable neonatal chest and abdominal projection radiographs, plain film was subjectively compared to CR hardcopy. Three pediatric radiologists graded overall image quality on a scale of one (poor) to five (excellent), as well as visualization of various anatomic structures (i.e., lung parenchyma, pulmonary vasculature, tubes/lines) and pathological findings (i.e., pulmonary interstitial emphysema, pleural effusion, pneumothorax). Results analyzed using a combined kappa statistic of the differences between scores from each matched set, combined over the three readers showed no statistically significant difference in overall image quality between screen- film and CR (p equals 0.19). Similarly, no statistically significant difference was seen between screen-film and CR for anatomic structure visualization and for visualization of pathological findings. These results indicate that the image quality of CR is comparable to plain film, and that CR may be a suitable alternative to screen-film imaging for portable neonatal chest and abdominal examinations.

Clinical evaluation of CR versus plain film for neonatal ICU applications

NASA Astrophysics Data System (ADS)

Andriole, Katherine P.; Brasch, Robert C.; Gooding, Charles A.; Gould, Robert G.; Huang, H. K.

1995-05-01

The clinical utility of computed radiography (CR) versus screen-film for neonatal intensive care unit (ICU) applications is investigated. The latest versions of standard ST-V and high- resolution HR-V CR imaging plates were compared via measurements of image contrast, spatial resolution and signal-to-noise. The ST-V imaging plate was found to have equivalent spatial resolution and object detectability at a lower required dose than the HR-V, and was therefore chosen as the CR plate to use in clinical trials in which a modified film cassette containing the CR imaging plate, a conventional screen and film was utilized. For 50 portable neonatal chest examinations, plain film was subjectively compared to the perfectly matched, simultaneously obtained CR hardcopy and softcopy images. Grading of overall image quality was on a scale of one (poor) to five (excellent). Readers rated the visualization of various structures in the chest (i.e., lung parenchyma, pulmonary vasculature, tubes/lines) as well as the visualization of pathologic findings. Preliminary results indicate that the image quality of both CR soft and hardcopy are comparable to plain film and that CR may be a suitable alternative to screen-film imaging for portable neonatal chest x rays.

Device to monitor sock use in people using prosthetic limbs: technical report.

PubMed

Sanders, Joan E; Murthy, Revathi; Cagle, John C; Allyn, Katheryn J; Phillips, Reid H; Otis, Brian P

2012-01-01

A device using radio frequency identification (RFID) technology was developed to continuously monitor sock use in people who use prosthetic limbs. RFID tags were placed on prosthetic socks worn by subjects with transtibial limb loss, and a high-frequency RFID reader and antenna were placed in a portable unit mounted to the outside of the prosthetic socket. Bench testing showed the device to have a maximum read range between 5.6 cm and 12.7 cm, depending on the RFID tag used. Testing in a laboratory setting on three participants with transtibial amputation showed that the device correctly monitored sock presence during sitting, standing, and walking activity when one or two socks were worn but was less reliable when more socks were used. Accurate detection was sensitive to orientation of the tag relative to the reader, presence of carbon fiber in the prosthetic socket, pistoning of the limb in the socket, and overlap among the tags. Use of ultra-high-frequency RFID may overcome these limitations. With improvements, the technology may prove useful to practitioners prescribing volume accommodation strategies for patients by providing information about sock use between clinical visits, including timing and consistency of daily sock-ply changes.

Technical Report: A device to monitor sock use on people using prosthetic limbs

PubMed Central

Sanders, Joan; Murthy, Revathi; Cagle, John; Allyn, Katheryn; Phillips, Reid

2015-01-01

A device using radio frequency identification technology (RFID) was developed to continuously monitor sock use on people using prosthetic limbs. RFID tags were placed on prosthetic socks worn by subjects with transtibial limb loss, and a high-frequency (HF) RFID reader and antenna were placed in a portable unit mounted to the outside of the prosthetic socket. Bench testing showed the device to have a maximum read range between 5.6 cm and 12.7 cm, depending on the RFID tag used. Testing in a laboratory setting on three participants with transtibial amputation showed that the device correctly monitored sock presence during sitting, standing, and walking activity when one or two socks were worn but was less reliable when more socks were used. Accurate detection was sensitive to orientation of the tag relative to the reader, presence of carbon fiber in the prosthetic socket, pistoning of the limb in the socket, and overlap among the tags. Use of ultra high frequency (UHF) RFID may overcome these limitations. With improvements, the technology may prove useful to practitioners prescribing volume accommodation strategies for patients by providing information about sock use between clinical visits, including timing and consistency of daily sock ply changes. PMID:23341315

Metal oxide based multisensor array and portable database for field analysis of antioxidants

PubMed Central

Sharpe, Erica; Bradley, Ryan; Frasco, Thalia; Jayathilaka, Dilhani; Marsh, Amanda; Andreescu, Silvana

2014-01-01

We report a novel chemical sensing array based on metal oxide nanoparticles as a portable and inexpensive paper-based colorimetric method for polyphenol detection and field characterization of antioxidant containing samples. Multiple metal oxide nanoparticles with various polyphenol binding properties were used as active sensing materials to develop the sensor array and establish a database of polyphenol standards that include epigallocatechin gallate, gallic acid, resveratrol, and Trolox among others. Unique charge-transfer complexes are formed between each polyphenol and each metal oxide on the surface of individual sensors in the array, creating distinct optically detectable signals which have been quantified and logged into a reference database for polyphenol identification. The field-portable Pantone/X-Rite© CapSure® color reader was used to create this database and to facilitate rapid colorimetric analysis. The use of multiple metal-oxide sensors allows for cross-validation of results and increases accuracy of analysis. The database has enabled successful identification and quantification of antioxidant constituents within real botanical extractions including green tea. Formation of charge-transfer complexes is also correlated with antioxidant activity exhibiting electron transfer capabilities of each polyphenol. The antioxidant activity of each sample was calculated and validated against the oxygen radical absorbance capacity (ORAC) assay showing good comparability. The results indicate that this method can be successfully used for a more comprehensive analysis of antioxidant containing samples as compared to conventional methods. This technology can greatly simplify investigations into plant phenolics and make possible the on-site determination of antioxidant composition and activity in remote locations. PMID:24610993

Rock art at the pleistocene/holocene boundary in Eastern South America.

PubMed

Neves, Walter A; Araujo, Astolfo G M; Bernardo, Danilo V; Kipnis, Renato; Feathers, James K

2012-01-01

Most investigations regarding the first americans have primarily focused on four themes: when the New World was settled by humans; where they came from; how many migrations or colonization pulses from elsewhere were involved in the process; and what kinds of subsistence patterns and material culture they developed during the first millennia of colonization. Little is known, however, about the symbolic world of the first humans who settled the New World, because artistic manifestations either as rock-art, ornaments, and portable art objects dated to the Pleistocene/Holocene transition are exceedingly rare in the Americas. Here we report a pecked anthropomorphic figure engraved in the bedrock of Lapa do Santo, an archaeological site located in Central Brazil. The horizontal projection of the radiocarbon ages obtained at the north profile suggests a minimum age of 9,370 ± 40 BP, (cal BP 10,700 to 10,500) for the petroglyph that is further supported by optically stimulated luminescence (OSL) dates from sediment in the same stratigraphic unit, located between two ages from 11.7 ± 0.8 ka BP to 9.9 ± 0.7 ka BP. These data allow us to suggest that the anthropomorphic figure is the oldest reliably dated figurative petroglyph ever found in the New World, indicating that cultural variability during the Pleistocene/Holocene boundary in South America was not restricted to stone tools and subsistence, but also encompassed the symbolic dimension.

Science Data Center concepts for moderate-sized NASA missions

NASA Technical Reports Server (NTRS)

Price, R.; Han, D.; Pedelty, J.

1991-01-01

The paper describes the approaches taken by the NASA Science Data Operations Center to the concepts for two future NASA moderate-sized missions, the Orbiting Solar Laboratory (OSL) and the Tropical Rainfall Measuring Mission (TRMM). The OSL space science mission will be a free-flying spacecraft with a complement of science instruments, placed in a high-inclination, sun synchronous orbit to allow continuous study of the sun for extended periods. The TRMM is planned to be a free-flying satellite for measuring tropical rainfall and its variations. Both missions will produce 'standard' data products for the benefit of their communities, and both depend upon their own scientific community to provide algorithms for generating the standard data products.

Proceedings of the Annual Symposium on Frequency Control (42nd) Held in Baltimore, Maryland on 1-3 June 1988

DTIC Science & Technology

1988-06-03

STrRIP IN FiG.2. 402 rV - C U’ 0-Z --. *L ot ’Z - 0o l or Pe T -lo 000r- O*SL- 0,X01- O’SZI- DlOSI- Osl - 00&z- OH/ Pul) IN 1 3v (1 4 d S)S0’I0I I-1...current, ac short-circuit current, and small-signal ac shunt resistance. Sulfur dosimeters were used to determine the All of these quantities were...measured in the photovoltaic incremental neutron fluences. The tolerance 2 of such mode under conditions of constant illumination using the dosimeters

Using Interactive 3D PDF for Exploring Complex Biomedical Data: Experiences and Solutions.

PubMed

Newe, Axel; Becker, Linda

2016-01-01

The Portable Document Format (PDF) is the most commonly used file format for the exchange of electronic documents. A lesser-known feature of PDF is the possibility to embed three-dimensional models and to display these models interactively with a qualified reader. This technology is well suited to present, to explore and to communicate complex biomedical data. This applies in particular for data which would suffer from a loss of information if it was reduced to a static two-dimensional projection. In this article, we present applications of 3D PDF for selected scholarly and clinical use cases in the biomedical domain. Furthermore, we present a sophisticated tool for the generation of respective PDF documents.

Tabular data and graphical images in support of the U.S. Geological Survey National Oil and Gas Assessment -- San Joaquin Basin (5010): Chapter 28 in Petroleum systems and geologic assessment of oil and gas in the San Joaquin Basin Province, California

USGS Publications Warehouse

Klett, T.R.; Le, P.A.

2007-01-01

This chapter describes data used in support of the assessment process. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on this CD–ROM. Computers and software may import the data without transcription from the portable document format (.pdf) files of the text by the reader. Because of the number and variety of platforms and software available, graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files).

Chapter 2: Tabular Data and Graphical Images in Support of the U.S. Geological Survey National Oil and Gas Assessment - The Wind River Basin Province

USGS Publications Warehouse

Klett, T.R.; Le, P.A.

2007-01-01

This chapter describes data used in support of the process being applied by the U.S. Geological Survey (USGS) National Oil and Gas Assessment (NOGA) project. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on this CD-ROM. Computers and software may import the data without transcription from the Portable Document Format files (.pdf files) of the text by the reader. Graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files) because of the number and variety of platforms and software available.

Novel label-free biosensing technology for monitoring of aqueous solutions (Conference Presentation)

NASA Astrophysics Data System (ADS)

Kehl, Florian; Bielecki, Robert; Follonier, Stephane; Dorokhin, Denis

2016-03-01

Waste water, drinking water and other industrial water sources are more and more/increasingly polluted with a large variety of contaminants, such as pesticides or residuals of pharmaceuticals. These compounds can impact human and animal organisms and lead to serious health issues. Today, in order to analyze the presence and quantity of the abovementioned micropollutants, samples are typically sent to specialized centralized laboratories and their processing may take up to several days. In order to meet the demand for continuous and consistent monitoring of aqueous solutions we propose a novel label-free technology system comprising proprietary chip and reader device designs. The core of the system is constituted by a planar-grated-waveguide (PGW) chip. Label-free biosensors, based on PGWs are sensitive to effective refractive index changes caused by the adsorption of biomolecules (micropollutants) onto the sensor surface or due to refractive index changes of the bulk solution. The presented reader device operates with a novel readout concept based on a scanning MEMS mirror for the angular interrogation of input grating couplers at a high repetition rate. The reader has fully integrated optics, electronics and fluidics and at the same time consumes limited energy (portable, field use ready). In the recent experiments, the effectiveness of the technology has been demonstrated with various liquids and bioassays showing (i) an excellent refractometric sensitivity with a limit of detection towards effective refractive index changes of ▵neff < 2 x 10-7, and (ii) the capability to perform affinity measurements for large (<150 kDa) and small (<250 Da) molecules.

An Interlaboratory Comparison of Dosimetry for a Multi-institutional Radiobiological

PubMed Central

Seed, TM; Xiao, S; Manley, N; Nikolich-Zugich, J; Pugh, J; van den Brink, M; Hirabayashi, Y; Yasutomo, K; Iwama, A; Koyasu, S; Shterev, I; Sempowski, G; Macchiarini, F; Nakachi, K; Kunugi, KC; Hammer, CG; DeWerd, LA

2016-01-01

Purpose An interlaboratory comparison of radiation dosimetry was conducted to determine the accuracy of doses being used experimentally for animal exposures within a large multi-institutional research project. The background and approach to this effort are described and discussed in terms of basic findings, problems and solutions. Methods Dosimetry tests were carried out utilizing optically stimulated luminescence (OSL) dosimeters embedded midline into mouse carcasses and thermal luminescence dosimeters (TLD) embedded midline into acrylic phantoms. Results The effort demonstrated that the majority (4/7) of the laboratories was able to deliver sufficiently accurate exposures having maximum dosing errors of ≤ 5%. Comparable rates of ‘dosimetric compliance’ were noted between OSL- and TLD-based tests. Data analysis showed a highly linear relationship between ‘measured’ and ‘target’ doses, with errors falling largely between 0–20%. Outliers were most notable for OSL-based tests, while multiple tests by ‘non-compliant’ laboratories using orthovoltage x-rays contributed heavily to the wide variation in dosing errors. Conclusions For the dosimetrically non-compliant laboratories, the relatively high rates of dosing errors were problematic, potentially compromising the quality of ongoing radiobiological research. This dosimetry effort proved to be instructive in establishing rigorous reviews of basic dosimetry protocols ensuring that dosing errors were minimized. PMID:26857121

[Measurement of scatter radiation on MDCT equipment using an OSL dosimeter].

PubMed

Tomita, Hironobu; Morozumi, Kunihiko

2004-11-01

The recent introduction of multi-detector row computed tomography (MDCT) has made it possible to scan the entire abdomen within approximately 10 sec in procedures such as interventional radiology computed tomography (IVRCT), which are associated with operator exposure. Therefore, anxious patients and patients who are not able to remain still can be examined with an assistant. In the present study, radiation exposure to the assistant was estimated, and the distribution of scattered radiation near the gantry was measured using an optically stimulated luminescence (OSL) dosimeter. Simultaneous measurements were obtained using a direction storage (DIS) dosimeter for reference. The maximum value of 1.47 mSv per examination was obtained at the point closest to the gantry's center (50 cm from the center at a height of 150 cm above the floor) . In addition, scattered radiation decreased as the measurement point was moved further from the gantry's center, falling below the limit of detection (0.1 mSv or less) at 200 cm and at the sides of the gantry. OSL dosimeters are also employed as personal dosimeters, permitting reliable values to be obtained easily. They were found to be an effective tool for the measurement of scattered radiation, as in the present study, helping to provide better understanding of the distribution of scattered radiation within the CT room.

An interlaboratory comparison of dosimetry for a multi-institutional radiobiological research project: Observations, problems, solutions and lessons learned.

PubMed

Seed, Thomas M; Xiao, Shiyun; Manley, Nancy; Nikolich-Zugich, Janko; Pugh, Jason; Van den Brink, Marcel; Hirabayashi, Yoko; Yasutomo, Koji; Iwama, Atsushi; Koyasu, Shigeo; Shterev, Ivo; Sempowski, Gregory; Macchiarini, Francesca; Nakachi, Kei; Kunugi, Keith C; Hammer, Clifford G; Dewerd, Lawrence A

2016-01-01

An interlaboratory comparison of radiation dosimetry was conducted to determine the accuracy of doses being used experimentally for animal exposures within a large multi-institutional research project. The background and approach to this effort are described and discussed in terms of basic findings, problems and solutions. Dosimetry tests were carried out utilizing optically stimulated luminescence (OSL) dosimeters embedded midline into mouse carcasses and thermal luminescence dosimeters (TLD) embedded midline into acrylic phantoms. The effort demonstrated that the majority (4/7) of the laboratories was able to deliver sufficiently accurate exposures having maximum dosing errors of ≤5%. Comparable rates of 'dosimetric compliance' were noted between OSL- and TLD-based tests. Data analysis showed a highly linear relationship between 'measured' and 'target' doses, with errors falling largely between 0 and 20%. Outliers were most notable for OSL-based tests, while multiple tests by 'non-compliant' laboratories using orthovoltage X-rays contributed heavily to the wide variation in dosing errors. For the dosimetrically non-compliant laboratories, the relatively high rates of dosing errors were problematic, potentially compromising the quality of ongoing radiobiological research. This dosimetry effort proved to be instructive in establishing rigorous reviews of basic dosimetry protocols ensuring that dosing errors were minimized.

Luminescence dating of the Zeketai loess section in the Ili Basin, northwestern China: Methodological considerations

NASA Astrophysics Data System (ADS)

Qin, Jintang; Zhou, Liping

2018-04-01

Loess deposits in Xinjiang, northwestern China are ideal archives for past environmental changes in the Westerlies-dominated central Asia. Among previous luminescence dating studies of loess in Xinjiang, few have attempted to systematically investigate the methodological aspects. In this study, we report results of a multiple-procedure luminescence dating of the Zeketai loess section in the Ili Basin, central Xinjiang. Optically stimulated luminescence (OSL) and post-infrared infrared stimulated luminescence (pIRIR) signals were used for quartz and polymineral grains of different sizes. The pIRIR ages obtained with two protocols agree well with each other and constrain the loess deposition between 50 ka and 88 ka. The OSL ages of fine-grained quartz are in stratigraphic order and range from 37 ka to 61 ka, but are ∼30% younger than the pIRIR295 ages of both fine and medium grained polyminerals. Although the causes of the discrepancy between the ages derived from different luminescence dating protocols are still to be understood, we stress that the quartz OSL ages of loess in this region are likely to be underestimated, especially for samples older than 40 ka. The polymineral or potassium feldspar pIRIR signal is recommended for dating loess in the Ili Basin, at least as an internal check.

The notion of climate-driven strath-terrace production assessed via dissimilar stream-process response to late Quaternary climate

USGS Publications Warehouse

García, Antonio F.; Mahan, Shannon

2014-01-01

Previous research results from the Gabilan Mesa are combined with new optically stimulated luminescence (OSL) age estimates and sedimentological analyses with the aim of identifying factors that inhibit climate-driven strath-terrace production, and factors that make possible strath-terrace production independent of climate forcing. The factors are revealed by comparing the morphostratigraphy and OSL age estimates of terraces in the adjacent San Lorenzo Creek and Pancho Rico Creek drainage basins of the central California Coast Ranges. OSL age estimates on San Lorenzo Creek fill-terrace alluvium overlying bedrock at two paleofluvial levels range between 50.5 and 41.3 ka and between 33.4 and 18.2 ka. These OSL age estimates indicate that although the channel of Pancho Rico Creek was degrading at these times, San Lorenzo Creek aggradation was synchronous with previously documented regional, climatically driven aggradation that elsewhere in southern California led to strath production and alluvial deposition. The regional-scale climate forcing events had different effects on San Lorenzo and Pancho Rico Creeks because of the influences of drainage-basin lithology on bedload size and tectonic tilting direction on base-level fall. The Holocene history of channel denudation and strath production of Pancho Rico Creek is also different from that of San Lorenzo Creek, and different from that of many other streams in southern California. After Pancho Rico Creek captured the upper part of the drainage basin of San Lorenzo Creek sometime after 15.5 to 11.7 ka, Pancho Rico Creek has been producing unpaired, erosional strath terraces. The weak, clay rich, fine-grained sedimentary rock underlying Pancho Rico Valley is an ideal substrate in which to form straths. The meandering channel of Pancho Rico Creek produces straths, and weathering resistant, relatively hard bedload introduced by stream capture ensures their preservation as strath terraces.

Preliminary results of chronostratigraphic field work, OSL-dating and morphogenetic reconstruction of an alluvial apron at Alborz southern foothill, Damghan basin, Iran

NASA Astrophysics Data System (ADS)

Büdel, Christian; Fuchs, Markus; Majid Padashi, Seyed; Baumhauer, Roland

2014-05-01

Here we present preliminary results of a chronostratigraphic study of an alluvial fan in the Damghan Basin, northern Iran. The basin sediments date back to the Mio- and Pliocene and therefore represent the starting point of alluvial fan aggradation. Today, the still active alluvial fans prograde from the Albors Mountain ranges and sit on the older sediment bodies. In this study, our focus is on the late Pleistocene to Holocene alluvial fan sedimentation history. The upper stratigraphy of the alluvial fans and intercalated lake deposits is characterized by six individual layers of gravels and fines, representing six different stratigraphic units. These units are described and classified by detailed geomorphological and stratigraphic mapping. To establish an alluvial fan chronology, six profiles were sampled for OSL dating. As expected, due to the high-energy transport system of alluvial fan aggradation in semi-desert environments, OSL dating of these sediments is challenging due to the problem of insufficient bleaching. Consequently, most of the samples are interpreted as maximum ages. However, the measurements show a consistent internal age structure and the overall OSL-based chronology is in agreement with the age model derived from our geomorphological analysis. As a first interpretation, based on surveyed geomorphological features and chronological analysis, we could identify seven morphodynamic phases, leading to a genetic model of alluvial fan aggradation. The oldest Pleistocene age estimate is derived from a former lake terrace. The following ages represent ongoing lake sediment deposition and the development of a proximal and mid-fan gravel cover. After the youngest lake deposits were accumulated within the Holocene, the lake starts to retreat and small alluvial fans are filling up the former lake bottom. This last sedimentation phase can be divided in at least two sub-phases, probably coupled to a lateral shifting of the active depositional lobe and to the abandonment and shallow incision of mid fan surfaces.

Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

PubMed

Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

2015-01-01

The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies.

Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy

PubMed Central

Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

2015-01-01

The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (−50 to −6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

Thermochronometry using red TL of quartz - a feasibility study from in-situ drill-hole samples

NASA Astrophysics Data System (ADS)

Schmidt, Christoph; Zöller, Ludwig

2015-04-01

Thermochronometry - the revelation of the temperature history of rock related to subsidence or uplift and erosion - relies on methods with closure temperatures >40-70 °C, such as (U-Th-Sm)/He or fission track analysis on apatite. These methods are applicable to young and tectonically active mountain ranges, but results of calculated mean denudation rates are too imprecise for older orogens. Several studies attested the quartz luminescence signal (325 °C TL peak, OSL fast component) isothermal decay at ambient temperatures as low as 56 °C (Prokein and Wagner, 1994; Herman et al., 2010; de Sarkar et al., 2013). The so far determined closure temperatures of the quartz luminescence thermochronometry system vary between ~35 °C for the OSL fast component (Herman et al., 2010) and ~70 °C for red thermoluminescence (RTL; Tsuchiya and Fujino, 2000) and are dependent on the cooling rate and the charge trap parameters. Although featuring a favourably low closure temperature - thus allowing to study the geologically most recent temperature history -, especially quartz OSL suffers from low dose saturation, limiting the application to highly erosive orogens. Saturation doses of RTL exceed those of OSL by a factor of 10 or more (Fattahi and Stokes, 2000), what opens up new perspectives in low-temperature thermochronometry. We here present experimental results on the general suitability of RTL for thermochronometry, obtained for samples from a drilling hole in the granitic basement of the Variscan Fichtelgebirge (Franconia, Germany). The samples allowed studying the RTL signal saturation level in-situ at different ambient temperatures up to ~55 °C (at 1831 m depth). Measurements confirmed depletion of the 325 °C RTL peak for ambient temperatures >25 °C, most probably for even lower temperatures. Irradiation experiments showed that the RTL signal is not in saturation for ambient temperatures >25 °C, even for this 'old' mountain range. We could further demonstrate that the luminescence sensitivity of samples strongly increases with rising ambient temperature, opposite to the findings of Ypma and Hochman (1991) for samples from sedimentary basins. References Fattahi, M., Stokes, S., 2000. Extending the time range of luminescence dating using red TL (RTL) from volcanic quartz. Radiation Measurements 32, 479-485. Herman, F., Rhodes, E.J., Braun, J., Heiniger, L., 2010. Uniform erosion rates and relief amplitude during glacial cycles in the Southern Alps of New Zealand, as revealed from OSL-thermochronology. Earth and Planetary Science Letters 297, 183-189. Prokein, J., Wagner, G.A., 1994. Analysis of thermoluminescent glow peaks in quartz derived from the KTB-drill hole. Radiation Measurements 23, 85-94. de Sarkar, S., Mathew, G., Pande, K., Chauhan, N., Singhvi, A.K., 2013. Rapid denudation of Higher Himalaya during late Pleistocence, evidence from OSL thermochronology. Geochronometria 40, 304-310. Tsuchiya, N., Fujino, K., 2000. Evaluation of cooling history of the Quaternary Takidani pluton using thermoluminescence technique. Proceedings World Geothermal Congress, Kyushu-Tohoku, Japan. Ypma, P.J., Hochman, M.B., 1991. Thermoluminescence geothermometry - a case study of the Otway basin. APEA Journal, 312-324.

Scintillation and storage luminescence properties of MgF2 transparent ceramics doped with Ce3+

NASA Astrophysics Data System (ADS)

Nakamura, Fumiya; Kato, Takumi; Okada, Go; Kawaguchi, Noriaki; Fukuda, Kentaro; Yanagida, Takayuki

2017-10-01

In this paper, we report basic optical properties and scintillation and storage luminescence properties of MgF2:Ce transparent ceramics with different doping concentrations of Ce (0.01, 0.1 and 1%) synthesized by spark plasma sintering (SPS). In scintillation, thermally-stimulated luminescence (TSL) and optically-stimulated luminescence (OSL), the dominant emissions were due to the 5d-4f transitions of Ce3+ which appeared in the near-UV region peaking around 320 and 360 nm. The scintillation was evaluated by X-ray irradiation while OSL was observed under 540 nm stimulation. In particular, the TSL sensitivity was high and showed a good linearity from 0.1 mGy to 1000 mGy.

Portable point-of-care blood analysis system for global health (Conference Presentation)

NASA Astrophysics Data System (ADS)

Dou, James J.; Aitchison, James Stewart; Chen, Lu; Nayyar, Rakesh

2016-03-01

In this paper we present a portable blood analysis system based on a disposable cartridge and hand-held reader. The platform can perform all the sample preparation, detection and waste collection required to complete a clinical test. In order to demonstrate the utility of this approach a CD4 T cell enumeration was carried out. A handheld, point-of-care CD4 T cell system was developed based on this system. In particular we will describe a pneumatic, active pumping method to control the on-chip fluidic actuation. Reagents for the CD4 T cell counting assay were dried on a reagent plug to eliminate the need for cold chain storage when used in the field. A micromixer based on the active fluidic actuation was designed to complete sample staining with fluorescent dyes that was dried on the reagent plugs. A novel image detection and analysis algorithm was developed to detect and track the flight of target particles and cells during each analysis. The handheld, point-of-care CD4 testing system was benchmarked against clinical cytometer. The experimental results demonstrated experimental results were closely matched with the flow cytometry. The same platform can be further expanded into a bead-array detection system where other types of biomolecules such as proteins can be detected using the same detection system.

Fissile material holdup measurement systems: an historical review of hardware and software

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chapman, Jeffrey Allen; Smith, Steven E; Rowe, Nathan C

The measurement of fissile material holdup is accomplished by passively measuring the energy-dependent photon flux and/or passive neutron flux emitted from the fissile material deposited within an engineered process system. Both measurement modalities--photon and neutron--require the implementation of portable, battery-operated systems that are transported, by hand, from one measurement location to another. Because of this portability requirement, gamma-ray spectrometers are typically limited to inorganic scintillators, coupled to photomultiplier tubes, a small multi-channel analyzer, and a handheld computer for data logging. For neutron detection, polyethylene-moderated, cadmium-back-shielded He-3 thermal neutron detectors are used, coupled to nuclear electronics for supplying high voltage tomore » the detector, and amplifying the signal chain to the scaler for counting. Holdup measurement methods, including the concept of Generalized Geometry Holdup (GGH), are well presented by T. Douglas Reilly in LA-UR-07-5149 and P. Russo in LA-14206, yet both publications leave much of the evolutionary hardware and software to the imagination of the reader. This paper presents an historical review of systems that have been developed and implemented since the mid-1980s for the nondestructive assay of fissile material, in situ. Specifications for the next-generation holdup measurements systems are conjectured.« less

Public accessibility of biomedical articles from PubMed Central reduces journal readership--retrospective cohort analysis.

PubMed

Davis, Philip M

2013-07-01

Does PubMed Central--a government-run digital archive of biomedical articles--compete with scientific society journals? A longitudinal, retrospective cohort analysis of 13,223 articles (5999 treatment, 7224 control) published in 14 society-run biomedical research journals in nutrition, experimental biology, physiology, and radiology between February 2008 and January 2011 reveals a 21.4% reduction in full-text hypertext markup language (HTML) article downloads and a 13.8% reduction in portable document format (PDF) article downloads from the journals' websites when U.S. National Institutes of Health-sponsored articles (treatment) become freely available from the PubMed Central repository. In addition, the effect of PubMed Central on reducing PDF article downloads is increasing over time, growing at a rate of 1.6% per year. There was no longitudinal effect for full-text HTML downloads. While PubMed Central may be providing complementary access to readers traditionally underserved by scientific journals, the loss of article readership from the journal website may weaken the ability of the journal to build communities of interest around research papers, impede the communication of news and events to scientific society members and journal readers, and reduce the perceived value of the journal to institutional subscribers.

Personal medical information system using laser card

NASA Astrophysics Data System (ADS)

Cho, Seong H.; Kim, Keun Ho; Choi, Hyung-Sik; Park, Hyun Wook

1996-04-01

The well-known hospital information system (HIS) and the picture archiving and communication system (PACS) are typical applications of multimedia to medical area. This paper proposes a personal medical information save-and-carry system using a laser card. This laser card is very useful, especially in emergency situations, because the medical information in the laser card can be read at anytime and anywhere if there exists a laser card reader/writer. The contents of the laser card include the clinical histories of a patient such as clinical chart, exam result, diagnostic reports, images, and so on. The purpose of this system is not a primary diagnosis, but emergency reference of clinical history of the patient. This personal medical information system consists of a personal computer integrated with laser card reader/writer, color frame grabber, color CCD camera and a high resolution image scanner optionally. Window-based graphical user interface was designed for easy use. The laser card has relatively sufficient capacity to store the personal medical information, and has fast access speed to restore and load the data with a portable size as compact as a credit card. Database items of laser card provide the doctors with medical data such as laser card information, patient information, clinical information, and diagnostic result information.

Chapter 3: Tabular Data and Graphical Images in Support of the U.S. Geological Survey National Oil and Gas Assessment - Western Gulf Province, Smackover-Austin-Eagle Ford Composite Total Petroleum System (504702)

USGS Publications Warehouse

Klett, T.R.; Le, P.A.

2006-01-01

This chapter describes data used in support of the process being applied by the U.S. Geological Survey (USGS) National Oil and Gas Assessment (NOGA) project. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on this CD-ROM. Computers and software may import the data without transcription from the Portable Document Format files (.pdf files) of the text by the reader. Because of the number and variety of platforms and software available, graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files).

Current trends in explosive detection techniques.

PubMed

Caygill, J Sarah; Davis, Frank; Higson, Seamus P J

2012-01-15

The detection of explosives and explosive-related compounds has become a heightened priority in recent years for homeland security and counter-terrorism applications. There has been a huge increase in research within this area-through both the development of new, innovative detection approaches and the improvement of existing techniques. Developments for miniaturisation, portability, field-ruggedisation and improvements in stand-off distances, selectivity and sensitivity have been necessary to develop and improve techniques. This review provides a consolidation of information relating to recent advances in explosive detection techniques without being limited to one specific research area or explosive type. The focus of this review will be towards advances in the last 5 years, with the reader being referred to earlier reviews where appropriate. Copyright © 2011. Published by Elsevier B.V.

A luminescence dating study of the sediment stratigraphy of the Lajia Ruins in the upper Yellow River valley, China

NASA Astrophysics Data System (ADS)

Zhang, Yuzhu; Huang, Chun Chang; Pang, Jiangli; Zhou, Yali; Zha, Xiaochun; Wang, Longsheng; Zhou, Liang; Guo, Yongqiang; Wang, Leibin

2014-06-01

Pedo-sedimentological fieldwork were carried out in the Lajia Ruins within the Guanting Basin along the upper Yellow River valley. In the eolian loess-soil sections on the second river terrace in the Lajia Ruins, we find that the land of the Qijia Culture (4.20-3.95 ka BP) are fractured by several sets of earthquake fissures. A conglomerated red clay covers the ground of the Qijia Culture and also fills in the earthquake fissures. The clay was deposited by enormous mudflows in association with catastrophic earthquakes and rainstorms. The aim of this study is to provide a luminescence chronology of the sediment stratigraphy of the Lajia Ruins. Eight samples were taken from an eolian loess-soil section (Xialajia section) in the ruins for optically stimulated luminescence (OSL) dating. The OSL ages are in stratigraphic order and range from (31.94 ± 1.99) ka to (0.76 ± 0.02) ka. Combined OSL and 14C ages with additional stratigraphic correlations, a chronological framework is established. We conclude that: (1) the second terrace of the upper part of Yellow River formed 35.00 ka ago, which was followed by the accumulation of the eolian loess-soil section; and (2) the eolian loess-soil section is composed of the Malan Loess of the late last glacial (MIS-2) and Holocene loess-soil sequences.

OSL - Orbiting Solar Laboratory: Our Window on the Sun

NASA Technical Reports Server (NTRS)

1991-01-01

The Sun, the nearest star, is crucial for life on Earth and has always been an object of intense study. Indeed, many of the fundamental principles of astrophysics, which seek to understand the physical nature of the universe, have been established through study of the Sun. Magnetic activity with the Sun drives powerful events on its surface and in its atmosphere. From the the Earth, these events can be seen as active region with their sunspots and solar flares. But to observe such phenomena in detail require more finely-tuned and powerful instruments, operating in space, across a broader range of the electomagnetic spectrum, than have ever been available in the past. Earth's atmosphere has always blurred the images received by visible-light telescopes on the ground. The atmosphere also acts as a barrier to the ultraviolet, extreme ultraviolet, and x rays that are similarly emitted from the Sun. All these wavelengths need to be captured, at the same moment in time, before the complex interrelationships of solar activity can be truly understood. The Orbiting Solar Laboratory (OSL), the prime NASA solar mission for the 1990's, is uniquely designed to 'see' across the wavelengths and so observe the fine evolving details of a wide range of phenomena on the surface of the Sun. By the turn of the century, OSL will enable scientists to solve mysteries that humankind has sought to unravel for thousands of years.

Dose profiles for lung and breast regions at prospective and retrospective CT coronary angiography using optically stimulated luminescence dosimeters on a 64-detector CT scanner.

PubMed

Funama, Yoshinori; Taguchi, Katsuyuki; Utsunomiya, Daisuke; Oda, Seitaro; Murasaki, Hiroo; Yamashita, Yasuyuki; Awai, Kazuo

2012-01-01

The purpose of our study was to acquire dose profiles at critical organs of lung and breast regions using optically stimulated luminescence (OSL) dosimeters; assess the actual radiation dose delivered at retrospective and prospective computed tomography coronary angiography (CTCA). Using a chest CT phantom we applied a prospectively-gated step-and-shoot- and a retrospectively-gated helical mode on a 64-detector row CT scanner. Retrospective scan mode was used with and without electrocardiogram (ECG) based tube current modulation. OSL dosimeters were used to measure dose profiles. In the both scan modes we acquired dose profiles and determined the mean and maximum dose in left lung and in left breast regions. In prospective mode, the mean dose was 21.53 mGy in left lung- and 23.59 mGy in left breast region. With respect to the retrospective mode, the mean dose with tube current modulation was 38.63 mGy for left lung- and 46.02 mGy for left breast region, i.e. 0.56 and 0.55 times lower than the mean dose without modulation. The OSL dosimeter is useful for measurement of the actual radiation dose along z-axis at lung and breast regions in the prospective and the retrospective CTCA. Copyright © 2011 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

A comparative evaluation of luminescence detectors: RPL-GD-301, TLD-100 and OSL-AL2O3:C, using Monte Carlo simulations

NASA Astrophysics Data System (ADS)

Benali, A.-H.; Medkour Ishak-Boushaki, G.; Nourreddine, A.-M.; Allab, M.; Papadimitroulas, P.

2017-07-01

The luminescent dosimeters are widely used in clinical practice, for the monitoring of patient dose in external radiation therapy. Three of the most common dosimeter categories are the thermoluminescence (TLDs), the radiophotoluminescence (RPLs) and the optically stimulated luminescence (OSLs), with similar physical processes on their properties. The aim of the present study is to compare and evaluate the dosimetric properties of three specific luminescent detectors namely: a) RPL glass dosimeter, commercially known as GD-301, b) lithium fluoride TLD-100 (LiF:Mg,Ti) and c) carbon-doped aluminum oxide (Al2O3:C). For this purpose, Monte Carlo simulations were applied, using the MCNP5 code to estimate the responses of these dosimeters in terms of absorbed dose, output factor, the angular and energy dependence. In the present study, we found that the differences between the output factors were less than ± 4.2% for all detector materials RPLGD, TLD and OSLD. The variations in sensitivity for angles up to ± 80 degrees from the central axis of the beam were approximately 0.5%, 0.8% and 1.5% for the TLD-100, GD-301 and Al2O3:C, respectively. The energy dependence of the RPL and OSL dosimeters are stated as less than a 2.2%, and within 5.8% for TLD.

Femoral head avascular necrosis: a frequently missed incidental finding on multidetector CT.

PubMed

Barille, M F; Wu, Jim S; McMahon, Colm J

2014-03-01

To determine the incidence of missed femoral head avascular necrosis (AVN) on pelvic computed tomography (CT) performed for clinical indications other than assessment for AVN. The study was a Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study. The picture archiving and communication system (PACS) database was queried for patients with diagnosis of femoral head AVN on magnetic resonance imaging (MRI), who also underwent pelvic multidetector CT after or <30 days before the MRI examination. The MRI and CT images of 144 hips of 72 patients (39 patients with reported AVN on MRI and 33 age-matched controls; mean age = 60 years, 28 male, 44 female), were reviewed in consensus by two readers in a randomized, blinded manner. Using MRI-proven CT-visible AVN as a reference standard, the incidence of missed AVN on initial CT interpretation was determined. Readers confirmed AVN in 33 patients on the MRI images. Nine hips with AVN underwent joint replacement of the affected joint(s) prior to subsequent CT and were excluded. Forty-three MRI-proven AVN cases in 28 patients (15 bilateral, 13 unilateral) were available for analysis. The study readers diagnosed 35/43 (81%) MRI-proven AVN cases in 22/28 (79%) patients. Four of the 35 (11%) cases of MRI-proven, CT-visible AVN were prospectively reported in 3/22 (14%) patients at initial clinical interpretation, with a miss rate of 89% per hip and 86% per patient. Multidetector CT has high accuracy for detection of AVN; however, this is frequently missed as an incidental finding (89% missed in the present study). Assessment for signs of femoral AVN should be part of routine search pattern in interpretation of pelvic CT. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Repeatability of Computerized Tomography-Based Anthropomorphic Measurements of Frailty in Patients With Pulmonary Fibrosis Undergoing Lung Transplantation.

PubMed

McClellan, Taylor; Allen, Brian C; Kappus, Matthew; Bhatti, Lubna; Dafalla, Randa A; Snyder, Laurie D; Bashir, Mustafa R

To determine interreader and intrareader repeatability and correlations among measurements of computerized tomography-based anthropomorphic measurements in patients with pulmonary fibrosis undergoing lung transplantation. This was an institutional review board-approved, Health Insurance Portability and Accountability Act-compliant retrospective study of 23 randomly selected subjects (19 male and 4 female; median age = 69 years; range: 66-77 years) with idiopathic pulmonary fibrosis undergoing pulmonary transplantation, who had also undergone preoperative thoracoabdominal computerized tomography. Five readers of varying imaging experience independently performed the following cross-sectional area measurements at the inferior endplate of the L3 vertebral body: right and left psoas muscles, right and left paraspinal muscles, total abdominal musculature, and visceral and subcutaneous fat. The following measurements were obtained at the inferior endplate of T6: right and left paraspinal muscles with and without including the trapezius muscles and subcutaneous fat. Three readers repeated all measurements to assess intrareader repeatability. Intrareader repeatability was nearly perfect (interclass correlation coefficients = 0.99, P < 0.001). Interreader agreement was excellent across all 5 readers (interclass correlation coefficients: 0.71-0.99, P < 0.001). Coefficients of variance between measures ranged from 3.2%-6.8% for abdominal measurements, but were higher for thoracic measurements, up to 23.9%. Correlation between total paraspinal and total psoas muscle area was strong (r 2 = 0.67, P < 0.001). Thoracic and abdominal musculature had a weaker correlation (r 2 = 0.35-0.38, P < 0.001). Measures of thoracic and abdominal muscle and fat area are highly repeatable in patients with pulmonary fibrosis undergoing lung transplantation. Measures of muscle area are strongly correlated among abdominal locations, but inversely correlated between abdominal and thoracic locations. Copyright © 2017 Elsevier Inc. All rights reserved.

Bone suppression technique for chest radiographs

NASA Astrophysics Data System (ADS)

Huo, Zhimin; Xu, Fan; Zhang, Jane; Zhao, Hui; Hobbs, Susan K.; Wandtke, John C.; Sykes, Anne-Marie; Paul, Narinder; Foos, David

2014-03-01

High-contrast bone structures are a major noise contributor in chest radiographic images. A signal of interest in a chest radiograph could be either partially or completely obscured or "overshadowed" by the highly contrasted bone structures in its surrounding. Thus, removing the bone structures, especially the posterior rib and clavicle structures, is highly desirable to increase the visibility of soft tissue density. We developed an innovative technology that offers a solution to suppress bone structures, including posterior ribs and clavicles, on conventional and portable chest X-ray images. The bone-suppression image processing technology includes five major steps: 1) lung segmentation, 2) rib and clavicle structure detection, 3) rib and clavicle edge detection, 4) rib and clavicle profile estimation, and 5) suppression based on the estimated profiles. The bone-suppression software outputs an image with both the rib and clavicle structures suppressed. The rib suppression performance was evaluated on 491 images. On average, 83.06% (±6.59%) of the rib structures on a standard chest image were suppressed based on the comparison of computer-identified rib areas against hand-drawn rib areas, which is equivalent to about an average of one rib that is still visible on a rib-suppressed image based on a visual assessment. Reader studies were performed to evaluate reader performance in detecting lung nodules and pneumothoraces with and without a bone-suppression companion view. Results from reader studies indicated that the bone-suppression technology significantly improved radiologists' performance in the detection of CT-confirmed possible nodules and pneumothoraces on chest radiographs. The results also showed that radiologists were more confident in making diagnoses regarding the presence or absence of an abnormality after rib-suppressed companion views were presented

Research, Recruitment, and Assessment Strategies From The Dune Undergraduate Geomorphology and Geochronology (DUGG) REU Site at the University of Wisconsin-Platteville

NASA Astrophysics Data System (ADS)

Rawling, J.; Presiado, R. S.; Hanson, P. R.

2013-12-01

The goals of the DUGG REU project included providing students with 1) significant field and laboratory training in geomorphology and geochronology, 2) an opportunity to participate in a project of regional significance to geomorphologists and Quaternary scientists and 3) cohort building opportunities resulting in relationships that will serve them throughout their graduate and/or professional STEM careers. Each cohort was provided with three opportunities to visit their chosen study sites and collect data. Students were introduced to their sites with geophysical surveying by conducting ground-penetrating radar transects. During the second and third field excursions students collected subsurface sediment samples with either a bucket auger or a portable vibracoring device. Student generated data from previous trips, including preliminary OSL data before the third trip, better informed subsequent sampling strategies. In total, the students measured the particle-size distributions from ~950 samples taken from 160 sites and dated 65 sand samples using optically-stimulated luminescence (OSL) dating. Efforts made to ensure a diverse applicant pool included the standard NSF and university websites, targeted emails, targeted recruitment at conferences, university visits, and collaborations with other undergraduate research centers. In total, approximately 25% of the participating DUGG students were members of minority groups underrepresented in the sciences (n=5), 65% were women (n=14) and one was a veteran of the Iraq conflict. The DUGG project included a Council on Undergraduate Research review during year one of the program to have external input on the project, and an aggressive internal assessment protocol that evaluated five measures related to the impact the project was having on the students. Over the three years of the project, the multiple annual program assessments were able to document increases in participants' technology literacy, perception toward geosciences, research techniques, and oral presentation skills from the beginning to the end of each DUGG cycle. The DUGG program also yielded effective gains in the student's geoscience content knowledge as measured by the assessment instruments. It is clear from the project assessments that the three years of DUGG had significant successes, and was a direct result of the careful consideration of each year's experience and evaluations. The combination of multiple visits to the research sites, rapid data turn around, diversity recruitment, and rigorous assessment ensured the successful achievement of the program goals and resulted in exceptional experiences for the DUGG students.

New optically stimulated luminescence ages provide evidence of MIS3 and MIS2 eolian activity on Black Mesa, northeastern Arizona, USA

USGS Publications Warehouse

Ellwein, A.L.; Mahan, S.A.; McFadden, L.D.

2011-01-01

Eolian deposition on the semiarid southern Colorado Plateau has been attributed to episodic aridity during the Quaternary Period. However, OSL ages from three topographically controlled (e.g. falling) dunes on Black Mesa in northeastern Arizona indicate that eolian sediments there were deposited in deep tributary valleys as early as 35-30. ka, with most sand deposited before 20. ka. In contrast, the oldest OSL ages for sand sheets fall within the Pleistocene-Holocene climatic transition (~. 12-8. ka). Thus most eolian sediment accumulated on Black Mesa under climatic conditions that were in general cooler, moister, and more variable than today, not more arid, pointing to a considerable increase in sediment supply. ?? 2010 University of Washington.

TL and OSL properties of beta irradiated Y2O3 nanocrystal

NASA Astrophysics Data System (ADS)

Shivaramu, N. J.; Lakshminarasappa, B. N.; Nagabhushana, K. R.; Tatumi, S. H.; Rocca, R. R.; Singh, Fouran

2017-05-01

Nanocrystalline yttrium oxide (Y2O3) is synthesized by low temperature sol-gel technique and synthesized material is annealed at 900°C. The annealed β-rayed Y2O3 two TL glows with prominent peak at 407 K and weak glow peak at 643 K were observed in all irradiated samples. It is found that TL glow peaks intensity linearly increases with increase in β-dose from 0.813 - 40.625 Gy. The TL kinetic parameters are calculated using glow curve deconvoluted (GCD) method. The TL glows exhibits general order kinetics. Intense optical stimulated luminescence (OSL) is observed in the Y2O3 sample. These material exhibits linearity and reproducibility and hence, it suggests that this material may be used as dosimetric applications.

Finnish spectrolite as high-dose gamma detector

NASA Astrophysics Data System (ADS)

Antonio, Patrícia L.; Caldas, Linda V. E.

2015-11-01

A natural material called spectrolite, from Finland, was studied in this work. The purpose was to test it in gamma radiation beams to verify its performance as a high-dose detector. From this material, pellets were manufactured with two different concentrations of Teflon and spectrolite, and their responses were verified using two luminescent techniques: thermoluminescence (TL) and optically stimulated luminescence (OSL). The TL and OSL signals were evaluated by means of characterization tests of the material response, after exposure to a nominal absorbed dose interval of 5 Gy to 10 kGy. The results obtained, for both concentrations, showed a good performance of this material in beams of high-dose gamma radiation. Both techniques were utilized in order to investigate the properties of the spectrolite+Teflon samples for different applications.

Detection of ESKAPE Bacterial Pathogens at the Point of Care Using Isothermal DNA-Based Assays in a Portable Degas-Actuated Microfluidic Diagnostic Assay Platform

PubMed Central

Renner, Lars D.; Zan, Jindong; Hu, Linda I.; Martinez, Manuel; Resto, Pedro J.; Siegel, Adam C.; Torres, Clint; Hall, Sara B.; Slezak, Tom R.

2016-01-01

ABSTRACT An estimated 1.5 billion microbial infections occur globally each year and result in ∼4.6 million deaths. A technology gap associated with commercially available diagnostic tests in remote and underdeveloped regions prevents timely pathogen identification for effective antibiotic chemotherapies for infected patients. The result is a trial-and-error approach that is limited in effectiveness, increases risk for patients while contributing to antimicrobial drug resistance, and reduces the lifetime of antibiotics. This paper addresses this important diagnostic technology gap by describing a low-cost, portable, rapid, and easy-to-use microfluidic cartridge-based system for detecting the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacterial pathogens that are most commonly associated with antibiotic resistance. The point-of-care molecular diagnostic system consists of a vacuum-degassed microfluidic cartridge preloaded with lyophilized recombinase polymerase amplification (RPA) assays and a small portable battery-powered electronic incubator/reader. The isothermal RPA assays detect the targeted ESKAPE pathogens with high sensitivity (e.g., a limit of detection of ∼10 nucleic acid molecules) that is comparable to that of current PCR-based assays, and they offer advantages in power consumption, engineering, and robustness, which are three critical elements required for the point-of-care setting. IMPORTANCE This paper describes a portable system for rapidly identifying bacteria in resource-limited environments; we highlight the capabilities of the technology by detecting different pathogens within the ESKAPE collection, which cause nosocomial infections. The system is designed around isothermal DNA-based assays housed within an autonomous plastic cartridge that are designed with the end user in mind, who may have limited technological training. Displaying excellent sensitivity and specificity, the assay systems that we demonstrate may enable future diagnoses of bacterial infection to guide the development of effective chemotherapies and may have a role in areas beyond health where rapid detection is valuable, including in industrial processing and manufacturing, food security, agriculture, and water quality testing. PMID:27986722

Detection of ESKAPE Bacterial Pathogens at the Point of Care Using Isothermal DNA-Based Assays in a Portable Degas-Actuated Microfluidic Diagnostic Assay Platform.

PubMed

Renner, Lars D; Zan, Jindong; Hu, Linda I; Martinez, Manuel; Resto, Pedro J; Siegel, Adam C; Torres, Clint; Hall, Sara B; Slezak, Tom R; Nguyen, Tuan H; Weibel, Douglas B

2017-02-15

An estimated 1.5 billion microbial infections occur globally each year and result in ∼4.6 million deaths. A technology gap associated with commercially available diagnostic tests in remote and underdeveloped regions prevents timely pathogen identification for effective antibiotic chemotherapies for infected patients. The result is a trial-and-error approach that is limited in effectiveness, increases risk for patients while contributing to antimicrobial drug resistance, and reduces the lifetime of antibiotics. This paper addresses this important diagnostic technology gap by describing a low-cost, portable, rapid, and easy-to-use microfluidic cartridge-based system for detecting the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) bacterial pathogens that are most commonly associated with antibiotic resistance. The point-of-care molecular diagnostic system consists of a vacuum-degassed microfluidic cartridge preloaded with lyophilized recombinase polymerase amplification (RPA) assays and a small portable battery-powered electronic incubator/reader. The isothermal RPA assays detect the targeted ESKAPE pathogens with high sensitivity (e.g., a limit of detection of ∼10 nucleic acid molecules) that is comparable to that of current PCR-based assays, and they offer advantages in power consumption, engineering, and robustness, which are three critical elements required for the point-of-care setting. This paper describes a portable system for rapidly identifying bacteria in resource-limited environments; we highlight the capabilities of the technology by detecting different pathogens within the ESKAPE collection, which cause nosocomial infections. The system is designed around isothermal DNA-based assays housed within an autonomous plastic cartridge that are designed with the end user in mind, who may have limited technological training. Displaying excellent sensitivity and specificity, the assay systems that we demonstrate may enable future diagnoses of bacterial infection to guide the development of effective chemotherapies and may have a role in areas beyond health where rapid detection is valuable, including in industrial processing and manufacturing, food security, agriculture, and water quality testing. Copyright © 2017 Renner et al.

Middle to Late Pleistocene coastal deposits of Eivissa (Western Mediterranean): Chronology and evolution.

NASA Astrophysics Data System (ADS)

Del Valle, Laura; Pomar, Francisco; Fornós, Joan J.; Gómez-Pujol, Lluís; Anechitei-Deacu, Valentina; Timar-Gabor, Alida

2016-04-01

This study deals with the sedimentary and stratigraphical description of Pleistocene deposits from seven coastal areas of Eivissa (Balearic Islands). Twenty two sedimentary facies have been described involving the succession of eolian, colluvial and edaphic environments. Carbonate sandstones, breccias and silty deposits are the main component of these sequences. Despite the extensive eolian systems outcropping along the coast of Eivissa, there are very few studies performed to chronological framework of these deposits. Luminescence measurements were carried out using an automated RisØ TL/OSL-DA-20 reader in the Luminescence Dating Laboratory of Babes-Bolyai University (Cluj-Napoca, Romania) under low intensity red light. OSL dating of nineteen eolian levels indicate that their deposition took place between the Middle and Late Pleistocene, establishing a paleoclimatic evolution of Eivissa Island since 755 ka to 70 Ka. Eolian activity in the Eivissa Island can be correlated with regression episodes which took place during cold periods associated with different isotopic stages, concretely the MIS 18, 16, 12, 10, 8, 6 and 4. Similar results have been obtained from many sites along the western Mediterranean Sea such as Mallorca (Pomar i Cuerda, 1979; Nielsen et al, 2004; Fornós et al, 2009), Sardinia (Andreucci et al, 2009; Pascucci et al, 2014), Liguria (Pappalardo et al., 2013). Keywords: Eolian dunes, Pleistocene, Climatic evolution, Eivissa. References - Andreucci, S.; Pascucci, V.; Murray, A. S.; Clemmensen, L. B. 2009. Late Pleistocene coastal evolution of San Giovanni di Sinis, west Sardinia (Western Mediterranean). Sedimentary Geology, 216: 104- 116 - Fornós, J.J.; Clemmensen, L.B.; Gómez-Pujol, L.; Murray, A. 2009. Late Pleistocene carbonate aeolianites on Mallorca, Western Mediterranean: a luminescence chronology. Quaternary Science reviews 28: 2697-2709. -Nielsen, K.A.; Clemmensen, L.B.; Fornós, J.J. 2004. Middle Pleistocene magnetostratigraphy and susceptibility stratigraphy: data from a carbonate aeolian system, Mallorca, Western Mediterranean. Quaternary Science Reviews, 23: 1733-1756 -Pappalardo, M.; Chelli, A.; Ciampalini, A.; Rellini, I.; Biagioni, F.; Brückner, H.; Fülling, A.; Firpo, M. 2013. Evolution of an Upper Pleistocene aeolianite in the northern Mediterranean (Liguria, NW Italy). Ital. j. Geosci. Vol. 132, 2: 290-303 -Pascucci, V.; Sechi, D.; Andreucci, S. 2014. Middle Pleistocene to Holocene coastal evolution of NW Sardinia (Mediterranean Sea, Italy). Quaternary International, 328-329: 3-20 -Pomar, L.; Cuerda, J. 1979. Los depósitos marinos pleistocénicos en Mallorca Acta Geológica Hispánica. Homenatge a Lluís Soler i Sarabaris. Vol. 14: 505-513

Rock Art at the Pleistocene/Holocene Boundary in Eastern South America

PubMed Central

Neves, Walter A.; Araujo, Astolfo G. M.; Bernardo, Danilo V.; Kipnis, Renato; Feathers, James K.

2012-01-01

Background Most investigations regarding the First Americans have primarily focused on four themes: when the New World was settled by humans; where they came from; how many migrations or colonization pulses from elsewhere were involved in the process; and what kinds of subsistence patterns and material culture they developed during the first millennia of colonization. Little is known, however, about the symbolic world of the first humans who settled the New World, because artistic manifestations either as rock-art, ornaments, and portable art objects dated to the Pleistocene/Holocene transition are exceedingly rare in the Americas. Methodology/Principal Findings Here we report a pecked anthropomorphic figure engraved in the bedrock of Lapa do Santo, an archaeological site located in Central Brazil. The horizontal projection of the radiocarbon ages obtained at the north profile suggests a minimum age of 9,370±40 BP, (cal BP 10,700 to 10,500) for the petroglyph that is further supported by optically stimulated luminescence (OSL) dates from sediment in the same stratigraphic unit, located between two ages from 11.7±0.8 ka BP to 9.9±0.7 ka BP. Conclusions These data allow us to suggest that the anthropomorphic figure is the oldest reliably dated figurative petroglyph ever found in the New World, indicating that cultural variability during the Pleistocene/Holocene boundary in South America was not restricted to stone tools and subsistence, but also encompassed the symbolic dimension. PMID:22384187

Provenance of sands from the confluence of the Amazon and Madeira rivers based on detrital heavy minerals and luminescence of quartz and feldspar

NASA Astrophysics Data System (ADS)

do Nascimento, Daniel R.; Sawakuchi, André O.; Guedes, Carlos C. F.; Giannini, Paulo C. F.; Grohmann, Carlos H.; Ferreira, Manuela P.

2015-03-01

Source-to-sink systems are poorly known in tropical rivers. For the Amazonian rivers, the majority of the provenance studies remain focused on the suspended load, implying a poor understanding of the processes governing production and distribution of sands. In this study, we perform heavy mineral and optically stimulated luminescence (OSL) analysis to cover the entire spectrum (heavy and light minerals fraction) of 29 sand samples of the Lower Madeira river region (Amazon and Madeira rivers), of which the main goal was to find provenance indicators specific to these rivers. Despite the tropical humid climate, the sands of the Amazon and Lower Madeira rivers are rich in unstable heavy minerals as augite, hypersthene, green hornblende and andalusite. The Madeira river is highlighted by its higher content of andalusite, with source attributed to the Amazon Craton (medium-to-high grade metamorphic rocks), while the Amazon river, upstream of the Madeira river mouth, has a signature of augite and hypersthene, that suggests an Andean provenance (volcanic rocks). Sands from the Madeira river can be tracked in the Amazon river by the increasing concentration in andalusite. OSL analysis of the light minerals fraction was used as an index of feldspar concentration and sedimentary history of quartz grains. Lower feldspar concentration and quartz grains with longer sedimentary history (higher OSL sensitivity) also point to a major contribution of cratonic sources for the sands in the Madeira river. While the sands from the Lower Madeira would be mainly supplied by cratonic rocks, previous work recognised that suspended sediments (silt and clay) are derived from Andean rocks. Therefore, we interpret a decoupling between the sources of sand and mud (silt and clay) under transport in the Madeira river. Andean sands (rich in augite and hypersthene) would be trapped in the foreland zones of the Beni and Mamoré tributaries. In the Amazon river sands, the low OSL sensitivity of the quartz, higher content of feldspar and unstable heavy mineral assemblage dominated by augite and hypersthene suggest both a fast transport from Andean sources with fine sediment bypass over foreland areas.

Procedural revision to the use-dilution methods: establishment of maximum log density value for test microbes on inoculated carriers.

PubMed

Tomasino, Stephen F; Pines, Rebecca M; Hamilton, Gordon C

2012-01-01

(Staphylococcus aureus) and 964.02 (Pseudomonas aeruginosa), were revised in 2009 to include a standardized procedure to measure the log density of the test microbe and to establish a minimum mean log density value of 6.0 (geometric mean of 1.0 x 10(6) CFU/carrier) to qualify the test results. This report proposes setting a maximum mean log density value of 7.0 (geometric mean of 1.0 x 10(7) CFU/carrier) to further standardize the procedure. The minimum value was based on carrier count data collected by four laboratories over an 8-year period (1999-2006). The data have been updated to include an additional 4 years' worth of data (2006-2010) collected by the same laboratories. A total of 512 tests were conducted on products bearing claims against P. aeruginosa and S. aureus with and without an organic soil load (OSL) added to the inoculum (as specified on the product label claim). Six carriers were assayed in each test, for a total of 3072 carriers. Mean log densities for each of the 512 tests were at least 6.0. With the exception of two tests, one for P. aeruginosa without OSL and one for S. aureus with OSL, the mean log densities did not exceed 7.5 (geometric mean of 3.2 x 10(7) CFU/carrier). Across microbes and OSL treatments, the mean log density (+/- SEM) was 6.80 (+/- 0.07) per carrier (a geometric mean of 6.32 x 10(6) CFUlcarrier) and acceptable repeatability (0.28) and reproducibility (0.31) SDs were exhibited. A maximum mean log density per carrier of 7.0 is being proposed here as a validity requirement for S. aureus and P. aeruginosa. A modification to the method to allow for dilution of the final test cultures to achieve carrier counts within 6.0-7.0 logs is also being proposed. Establishing a range of 6.0-7.0 logs will help improve the reliability of the method and should allow for more consistent results within and among laboratories.

Preliminary constraints on the kinetics of OSL thermochronology

NASA Astrophysics Data System (ADS)

Guralnik, B.; Herman, F.; Lowick, S.; Preusser, F.; Rhodes, E. J.

2010-12-01

Utilizing the fact that temperature exerts a strong control on the retention of radiogenic products at their production sites (and hence their rate of accumulation), thermochronology is an extension of geochronology used to elucidate the cooling histories (t-T trajectories) of rocks over time (Dodson, 1973). Here we present a potential thermochronometer based on the optically stimulated luminescence (OSL) signal of bedrock quartz, with an estimated “closure” temperature of ~25-40°C (-dT/dt=10°C/Ma). In this method, the radiogenic “products” measured are electrons trapped at the naturally occurring lattice defects (electrically unbalanced sites). These electrons can be subsequently released back into the conduction band by exposure to heat and/or light. The mean lifetime of an electron in a particular trapping site is well described by an Arrhenius relationship of the form τ=s-1exp(-E/kT), where E and s are activation energy and frequency factors, respectively, and k is Boltzmann’s constant. Reported lifetimes of the major trap types at 20°C are well beyond Ma-timescale, but for typical natural radioactivity dose rates, these traps saturate well before ~0.5 Ma. In the current work, we analyzed the OSL signals of bedrock quartz from the KTB-VB drillhole (Southern Germany), where long-term stable temperature conditions provide a natural isothermal holding experiment at a Ma-timescale. Eleven core samples from a depth range of 560 m - 2335 m (22°C - 71°C, respectively), were processed to obtain an unbleached quartz fraction of 180-250 µm. Natural and regenerated luminescence signals were measured by stimulation with infrared and then blue light using a single-aliquot regeneration (SAR) protocol. As a function of sample depth, the measured OSL signal varies from a saturated signal at shallow depths to reset signals below a depth of 1 km (i.e., ambient rock temperature higher than 40°C). Several unstable trapping sites with potentially different closure temperatures are suggested by comparison of the natural to regenerated signals.

Stratigraphic Reconstruction of a Late Pleistocene Cypress Forest Discovered on the Northern Gulf of Mexico Continental Shelf

NASA Astrophysics Data System (ADS)

Gonzalez Rodriguez, S. M.; Bentley, S. J.; Obelcz, J.; Truong, J. T.; DeLong, K. L.; Xu, K.; Harley, G. L.; Reese, C. A.; Caporaso, A.; Shen, Z.

2017-12-01

A previously buried bald cypress forest (Taxodium distichum) was discovered on the continental shelf, offshore of Orange Beach, Alabama, USA, in 20 m water depth. The forest was possibly exhumed by Hurricane Ivan in 2004, and is now exposed as stumps in life position in a trough located in the northern Gulf of Mexico continental shelf seafloor. We are investigating the local stratigraphy, paleo-landscape, and mode of forest preservation of this unique site. In August 2015 and July 2016, submersible vibracores (18 in total) were collected. Core analysis included: bulk density and imaging via Geotek multi sensor core logger, sediment grain size, structure, and organic content via loss-on-ignition. Selected samples have been dated using 14C and optically stimulated luminescence (OSL) methods. Multibeam and CHIRP subbottom bathymetry provide context for litho- and chrono-stratigraphy of the site. Integration of core lithostratigraphy and modern shelf bathymetry reveal Holocene transgressive sands blanketing diverse sedimentary facies that are truncated by the late Pleistocene-early Holocene ravinement. Deposits below the ravinement surface include interbedded sand and mud (exact age unknown, but possibly pertaining to a shallow marine environment), overlying a floodplain/swamp facies of woody debris, peat, and mud (provisionally dated by 14C to 41-45 ka). These units grade laterally into paleosols that appear to be 10-15 ka older, based on recently obtained preliminary OSL dates. Occurrence of paleosols and swamp deposits of broadly similar age and elevation suggests that the ancient landscape possessed topographic relief that allowed wetland and upland habitats to develop in close proximity. These new OSL dates enhance our initial hypothesis that floodplain aggradation in the area was a key factor that might have allowed forest preservation. The timing of temporary sea level rises (SLR) ca. 40 and 60 ka. with our 14C and preliminary OSL dates, suggests that floodplain aggradation associated with SLRs could have buried the swamp and forest sediments. Variable paleo-topography in the area at the time of burial provided enough sediment to keep the cypress forest blanketed, withstanding periods of erosion as sea level fluctuated through the late Pleistocene to Holocene, thus facilitating forest preservation.

SU-G-IeP2-04: Dosimetric Accuracy of a Monte Carlo-Based Tool for Cone-Beam CT Organ Dose Calculation: Validation Against OSL and XRQA2 Film Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chesneau, H; Lazaro, D; Blideanu, V

Purpose: The intensive use of Cone-Beam Computed Tomography (CBCT) during radiotherapy treatments raise some questions about the dose to healthy tissues delivered during image acquisitions. We hence developed a Monte Carlo (MC)-based tool to predict doses to organs delivered by the Elekta XVI kV-CBCT. This work aims at assessing the dosimetric accuracy of the MC tool, in all tissue types. Methods: The kV-CBCT MC model was developed using the PENELOPE code. The beam properties were validated against measured lateral and depth dose profiles in water, and energy spectra measured with a CdTe detector. The CBCT simulator accuracy then required verificationmore » in clinical conditions. For this, we compared calculated and experimental dose values obtained with OSL nanoDots and XRQA2 films inserted in CIRS anthropomorphic phantoms (male, female, and 5-year old child). Measurements were performed at different locations, including bone and lung structures, and for several acquisition protocols: lung, head-and-neck, and pelvis. OSLs and film measurements were corrected when possible for energy dependence, by taking into account for spectral variations between calibration and measurement conditions. Results: Comparisons between measured and MC dose values are summarized in table 1. A mean difference of 8.6% was achieved for OSLs when the energy correction was applied, and 89.3% of the 84 dose points were within uncertainty intervals, including those in bones and lungs. Results with XRQA2 are not as good, because incomplete information about electronic equilibrium in film layers hampered the application of a simple energy correction procedure. Furthermore, measured and calculated doses (Fig.1) are in agreement with the literature. Conclusion: The MC-based tool developed was validated with an extensive set of measurements, and enables the organ dose calculation with accuracy. It can now be used to compute and report doses to organs for clinical cases, and also to drive strategies to optimize imaging protocols.« less

Optimizing combined GPR, OSL and LiDAR (GOaL) to extract paleoenvironmental records and decipher shoreline evolution

NASA Astrophysics Data System (ADS)

Dougherty, A. J.; Choi, J. H.; Turney, C. S.; Dosseto, A.

2017-12-01

Records of past sea levels, storms, sediment supply and their impacts on the coastline are crucial for projecting likely shoreline changes resulting from anthropogenic warming. High-resolution geophysics, geochronology, and remote sensing techniques offer an optimal way to extract these records and decipher shoreline evolution. These methods include Light Detection and Ranging (LiDAR for imaging barrier morphologies in three dimensions), Ground Penetrating Radar (GPR for detecting paleo-dune, beach and nearshore stratigraphy) and Optically Stimulated Luminescence (OSL for dating deposition of sand grains along paleoshorelines). Each of these teqniques have been applied to coastal research over the decades since they were first introduced. Recently there has been a rapid increase their use since LiDAR became more available, GPR more user-friendly, and OSL more accessible. These methods have the potential to produce both detailed and voluminous datasets that can overwhelm or obscure significant features, such that discrepancies in analysis and/or presentation may lead to erroneous interpretations. In contrast, when utilized correctly on prograded barriers these methods (independently or in various combinations) have produced storm records, constructed sea-level curves, quantified sediment budgets, and deciphered coastal evolution. Therefore, combining the application of GPR, OSL, and LiDAR (GOaL) on one prograded barrier has the potential to generate detailed records of storms, sea level, and sediment supply for that coastline. Obtaining this GOaL hat-trick can provide valuable insights into how these three factors influenced past and future barrier evolution. Here we argue that systematically achieving GOaL hat-tricks on some of the 300+ prograded barriers worldwide would allow us to disentangle local patterns of sediment supply from regional effects of storms or global changes in sea level, allowing direct comparison to climate proxy records. To fully realize this aim requires standardization of methods to optimize results. The impetus for this initiative is to establish a framework for consistent data analysis that maximizes the potential of GOaL to contribute to climate change research and assist coastal communities in mitigating future impacts of global warming.

Mid-Holocene stabilization of the Karakum and Kyzylkum sand seas, central Asia - evidence from OSL ages

NASA Astrophysics Data System (ADS)

Maman, Shimrit; Tsoar, Haim; Blumberg, Dan G.; Porat, Naomi

2013-04-01

Sand seas (ergs) are large areas of deserts covered by wind-swept sand with varying degrees of vegetation cover. The Kyzylkum and Karakum ergs have accumulated in the Turan basin, northwest of the Hindu Kush range, and span from south Turkmenistan to the Syrdarya River in Kazakhstan. These ergs are dissected by the Amudarya River; To the north lies the Kyzylkum (red sands) and to the south the Karakum (black sands). This area is understudied, and little information has been published regarding the sands stabilization processes and deposition ages. This research focuses on identifying and mapping the ergs of Central Asia and analyzing the climate factors that set the dunes into motion and that stabilized them. A variety of spaceborne imagery with varying spectral and spatial resolutions was used. These images provide the basis for mapping sand distribution, dune forms, and vegetation cover. Wilson (1973) defined these ergs as active based on precipitation. Our results show that they are mostly stabilized, with an estimated area of ~260,000 sq. Km for Kara-Kum , and ~195,500 sq. Km for the Kyzyl-Kum . Meteorological analysis of wind and precipitation data indicate a low wind energy environment (DP<200) and sufficient rainfall (>100 mm) to which is essential for vegetation cover. We present the first optically stimulated luminescence (OSL) ages from the upper meter of 14 exposed sections from both ergs. The age of the sand samples was determined as ~Mid-Holocene by OSL, which provides an insight into past climate characteristics. These ages indicate extensive sand and dune stabilization during the Mid-Holocene. GIS analysis was performed in parallel with field work to validate and verify the results. The OSL ages, coupled with a compilation of regional palaeoclimatic data, corroborate and reinforce the previously proposed Mid-Holocene Liavliakan phase, known to reflect a warmer, wetter, less windy climate than persists today and that resulted in dune stabilization around Mid-Holocene. This study emphasizes the importance of regional climatic control on aeolian activity and is the first to show when these vast sand seas were stabilized.

Central Asian sand seas climate change as inferred from OSL dating

NASA Astrophysics Data System (ADS)

Maman, Shimrit; Tsoar, Haim; Blumberg, Dan; Porat, Naomi

2014-05-01

Luminescence dating techniques have become more accessible, widespread, more accurate and support studies of climate change. Optically stimulated luminescence (OSL) is used to determine the time elapsed since quartz grains were last exposed to sunlight, before they were buried and the dune stabilized. Many sand seas have been dated extensively by luminescence, e.g., the Kalahari, Namib the Australian linear dunes and the northwestern Negev dune field, Israel. However, no ages were published so far from the central Asian sand seas. The lack of dune stratigraphy and numerical ages precluded any reliable assessment of the paleoclimatic significance of dunes in central Asia. Central Asian Sand seas (ergs) have accumulated in the Turan basin, north-west of the Hindu Kush range, and span from south Turkmenistan to the Syr-Darya River in Kazakhstan. These ergs are dissected by the Amu-Darya River; to its north lies the Kyzylkum (red sands) and to its south lies the Karakum (black sands). Combined, they form one of the largest sand seas in the world. This area is understudied, and little information has been published regarding the sands stabilization processes and deposition ages. In this study, OSL ages for the Karakum and Kyzylkum sands are presented and analysis of the implications of these results is provided. Optical dates obtained in this study are used to study the effects climatic changes had on the mobility and stability of the central Asian sand seas. Optically stimulated luminescence ages derived from the upper meter of the interdune of 14 exposed sections from both ergs, indicate extensive sand and dune stabilization during the mid-Holocene. This stabilization is understood to reflect a transition to a warmer, wetter, and less windy climate that generally persisted until today. The OSL ages, coupled with a compilation of regional paleoclimatic data, corroborate and reinforce the previously proposed Mid-Holocene Liavliakan phase, known to reflect a warmer, wetter, and less windy climate that persists until today and resulted in dune stabilization around the Mid-Holocene. This study, solidifies our results regarding the Kyzylkum and Karakum sand seas dynamics, ages, and emphasizes the importance of regional climatic control on aeolian activity.

Soil development in OSL dated sandy dune substrates under Quercus robur Forest (Netherlands)

NASA Astrophysics Data System (ADS)

van Mourik, J. M.; Nierop, Ir. K.; Verstraten, J. M.

2009-04-01

Coastal dune landscapes are very dynamic. The present distribution of vegetation and soil is the result of over 2000 years of natural processes and human management. The initial soil development was controlled by an increase of the organic matter content, which consisted mainly of decomposed roots of grasses (rhizomull), and a decrease of the soil pH to 3-4 by decalcification. This stage was followed by the development of a deciduous forest, which was dominated by Quercus robur. Since 1600 AD, a large part of the deciduous forest that dominated the east side of the coastal dune landscape transferred in expensive residential areas and urbanizations. Nevertheless some parts of the oak forest belt remained. The present forest soils are acid and the controlling soil processes are leaching of sesquioxides and storage of organic matter in mormoder humus forms. The sustainability of ecosystems is closely related to the quality of the humus form, controlling nutrient cycling and water supply. Therefore, improve of knowledge of humus form development and properties is important. We applied soil micromorphology and pyrolysis-gas chromatography/mass spectrometry (GC/MS) to investigate more details of humus form development at two locations (Duivendrift and Hoek van Klaas) in the coastal dune area of the Amsterdamse Waterleidingduinen (near Haarlem, the Netherlands). However, to understand forest soil development, including the organic matter composition in the humus form, the age of the substrate and the forest is required. Therefore, we used tradition techniques as pollen analysis and radiocarbon dating but also the recently introduced optical stimulated luminescence (OSL) dating technique. OSL dating works excellent for aeolian sandy deposits with a high percentage of quartz grains. The OSL age is defined as the time after the last bleaching by solar radiation of mineral grains. Or in other words, the start of a stable period without sand drifting. In the Ah horizons we observed palynological traces of a former dune landscape with grasses and typical dune land shrubs. The F and H horizons were dominated by Quercus pollen. In thin sections we found that in the upper part of the F horizons the soil skeleton was formed by leaf litter fragments that were fragmented and decomposed by fungi and micro arthropods. The soil skeleton of the lower part of the F horizons consisted of a mixture of leaf litter fragments and (dead) root fragments. In this part of the profile, fungi and micro arthropods were also responsible for the physical and chemical organic matter decomposition. The soil skeleton of the Ah horizons was formed by mineral grains in which small sized organic aggregates occurred. These aggregates may have four possible sources: (1) sinsedimentary aggregates, involved in sand drifting, (2) fecal relicts from decomposed (older) roots of a former dune land vegetation, (2) fecal relicts from decomposed (younger) roots of the forest and its understory, and (3) infiltrated parts of fecal pallets from the overlying F horizons. The calibrated radiocarbon dates of organic matter from the upper 5 cm of the Ah horizons go back to around 1960 AD. This points to a 45 year period for the development of the ectorganic horizons, assuming that fresh organic matter did not ‘contaminate' the radiocarbon dating. The OSL the ages of quartz grains from the upper 5 cm of the Ah horizons indicate landscape stabilization around 1800AD implying that two centuries were available for vegetation and soil development. There seems to be a significant difference between the OSL and 14C ages of the top of the Ah horizon. The OSL dates are very reliable. They indicate the correct time of the transformation of drift sand into stable, vegetated landscape. The pollen spectra of the Ah horizon show traces of dune grass and shrub landscape, but probably these pollen grains originate from sinsedimentary organic aggregates. And during the juvenile phase of a quercus forest, the quercus pollen production is very low and other wind pollinated grains from dune grasses and shrubs can dominate the pollen spectra. Based upon OSL dates, a period of 200 year forest soil development is more reliable than the 14C based 45 year. We must reject the 14C ages, due to complexity of sources of soil organic matter in the Ah horizon The organic matter as investigated by analytical pyrolysis and thermally assisted hydrolysis and methylation and subsequent analysis by GC/MS revealed a major oak-derived picture. The L+F1 horizons reflected relatively undecomposed organic matter mainly derived from leaves. By contrast, in both F2+H and the Ah horizons leaf material was accompanied by root-derived components, particularly suberin. The latter may originate from barks as well, but in the Ah horizons the contribution of roots was most probably much greater. Apart from a common transformation pattern (decrease of polysaccharides, degradation of lignin and accumulation of lipids), a very small contribution of C26 alkanol indicated a chemical fingerprint of the previous grass vegetation. In conclusion: chemical analysis confirmed the soil micromorphological data, and the application of OSL dating improves our knowledge about geochronology of the system.

CW-OSL measurement protocols using optical fibre Al2O3:C dosemeters.

PubMed

Edmund, J M; Andersen, C E; Marckmann, C J; Aznar, M C; Akselrod, M S; Bøtter-Jensen, L

2006-01-01

A new system for in vivo dosimetry during radiotherapy has been introduced. Luminescence signals from a small crystal of carbon-doped aluminium oxide (Al2O3:C) are transmitted through an optical fibre cable to an instrument that contains optical filters, a photomultiplier tube and a green (532 nm) laser. The prime output is continuous wave optically stimulated luminescence (CW-OSL) used for the measurement of the integrated dose. We demonstrate a measurement protocol with high reproducibility and improved linearity, which is suitable for clinical dosimetry. A crystal-specific minimum pre-dose is necessary for signal stabilisation. Simple background subtraction only partially removes the residual signal present at long integration times. Instead, the measurement protocol separates the decay curve into three individual components and only the fast and medium components were used.

Monolithic Integrated Radiation Sensor Using Stimulated Luminescence From Alumina

NASA Technical Reports Server (NTRS)

McKeever, S. W. S.; Yukihara, E. G.; Stoebe, T. G.; Chen, T.-C.

2005-01-01

The project goal was to design and test a monolithic integrated device for radiation sensing, using optically stimulated luminescence (OSL) from Al2O3:C. The device would consist of GaN/InGaN-based components epitaxially grown on each side of a A12O3:C substrate. Radiation energy stored in the substrate would be stimulated by visible emission from a GaN light-emitting diode (LED) grown on one side of the device, and the OSL emission from the substrate (in the blue region of the spectrum) would be detected by the InGaN pi-n diode grown on the other side of the substrate. The primary application of the device would be in space radiation environments. Thus, two major research thrusts were launched during this project. Firstly, research at Oklahoma State University (Dr. Stephen W.S. McKeever and Dr. E.G. Yukihara) concentrated on characterization of the OSL properties of Al2O3:C in radiation fields typical of those experienced in low-Earth orbit. Secondly, research at the University of Washington (Co-Is, Dr. T.G. Stoebe and Dr. T. Chen) focused of device development and GaN/InGaN epitaxial growth. While progress in each line of research has been substantial, the ultimate goal (that of producing a working prototype device) has not yet been reached. We detail the research progress and identify outstanding issues in this paper.

Assessing sedimentation rates at Usumacinta and Grijalva river basin (Southern Mexico) using OSL and suspended sediment load analysis: A study from the Maya Classic Period

NASA Astrophysics Data System (ADS)

Munoz-Salinas, E.; Castillo, M.; Sanderson, D.; Kinnaird, T.; Cruz-Zaragoza, E.

2013-12-01

Studying sedimentation rates on floodplains is key to understanding environmental changes occurred through time in river basins. The Usumacinta and Grijalva rivers flow most of their travel through the southern part of Mexico, forming a large river basin, crossing the states of Chiapas and Tabasco. The Usumacinta-Grijalva River Basin is within the 10 major rivers of North America, having a basin area of ~112 550 km2. We use the OSL technique for dating two sediment profiles and for obtaining luminescence signals in several sediment profiles located in the streambanks of the main trunk of the Usumacinta and Grijalva rivers. We also use mean annual values of suspended sediment load spanning ~50 years to calculate the sedimentation rates. Our OSL dating results start from the 4th Century, when the Maya Civilization was at its peak during the Classic Period. Sedimentation rates show a notable increase at the end of the 19th Century. The increase of the sedimentation rates seems to be related to changes in land uses in the Sierra Madre de Chiapas and Altos de Chiapas, based on deforestation and land clearing for developing new agrarian and pastoral activities. We conclude that the major environmental change in the basin of the Usumacinta and Grijalva Rivers since the Maya Classic Period was generated since the last Century as a result of an intense anthropogenic disturbance of mountain rain forest in Chiapas.

Chapter 6. Tabular data and graphical images in support of the U.S. Geological Survey National Oil and Gas Assessment-East Texas basin and Louisiana-Mississippi salt basins provinces, Jurassic Smackover interior salt basins total petroleum system (504902), Travis Peak and Hosston formations.

USGS Publications Warehouse

,

2006-01-01

This chapter describes data used in support of the process being applied by the U.S. Geological Survey (USGS) National Oil and Gas Assessment (NOGA) project. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on the CD-ROM. Computers and software may import the data without transcription from the Portable Document Format files (.pdf files) of the text by the reader. Because of the number and variety of platforms and software available, graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files).

Chapter 3. Tabular data and graphical images in support of the U.S. Geological Survey National Oil and Gas Assessment--East Texas basin and Louisiana-Mississippi salt basins provinces, Jurassic Smackover Interior salt basins total petroleum system (504902), Cotton Valley group.

USGS Publications Warehouse

Klett, T.R.; Le, P.A.

2006-01-01

This chapter describes data used in support of the process being applied by the U.S. Geological Survey (USGS) National Oil and Gas Assessment (NOGA) project. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on the CD-ROM. Computers and software may import the data without transcription from the Portable Document Format files (.pdf files) of the text by the reader. Because of the number and variety of platforms and software available, graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files).

Vodcasting for Everyone

NASA Astrophysics Data System (ADS)

Hurt, R.; Christensen, L. L.

2008-06-01

Video podcasting, or vodcasting, is the latest evolution of the podcast revolution. The market for on-demand content spans the gamut, ranging from portable media players to computers, and increasingly to televisions through home media centers. This new mode of accessing video content is rapidly growing in popularity, particularly among younger audiences. Because it allows a direct link between consumer and content producer, bypassing traditional media networks, it is ideal for EPO efforts. Even modest budgets can yield compelling astronomy vodcasts that will appeal to a large audience. Gateways like the iTunes Music Store and YouTube have created new content markets where none existed before. This paper highlights the key steps for producing a vodcast. The reader will see how to make (or improve) a video podcast for science communication purposes learn about some of the latest developments in this rapidly-evolving field.

Vodcasting for Everyone

NASA Astrophysics Data System (ADS)

Christensen, L. L.; Hurt, R. L.

2008-06-01

Video podcasting, or vodcasting, is the latest evolution of the podcast revolution. The market for on-demand content spans the gamut, ranging from portable media players to computers, and increasingly to televisions through home media centres. This new mode of accessing video content is rapidly growing in popularity, particularly among younger audiences. Because it allows a direct link between consumer and content producer, bypassing traditional media networks, it is ideal for EPO efforts. Even modest budgets can yield compelling astronomy vodcasts that will appeal to a large audience. Gateways like the iTunes Music Store and YouTube have created new content markets where none existed before. This paper highlights the key steps for producing a vodcast. The reader will see how to make (or improve) a video podcast for science communication purposes learn about some of the latest developments in this rapidly-evolving field.

Barcoded microchips for biomolecular assays.

PubMed

Zhang, Yi; Sun, Jiashu; Zou, Yu; Chen, Wenwen; Zhang, Wei; Xi, Jianzhong Jeff; Jiang, Xingyu

2015-01-20

Multiplexed assay of analytes is of great importance for clinical diagnostics and other analytical applications. Barcode-based bioassays with the ability to encode and decode may realize this goal in a straightforward and consistent manner. We present here a microfluidic barcoded chip containing several sets of microchannels with different widths, imitating the commonly used barcode. A single barcoded microchip can carry out tens of individual protein/nucleic acid assays (encode) and immediately yield all assay results by a portable barcode reader or a smartphone (decode). The applicability of a barcoded microchip is demonstrated by human immunodeficiency virus (HIV) immunoassays for simultaneous detection of three targets (anti-gp41 antibody, anti-gp120 antibody, and anti-gp36 antibody) from six human serum samples. We can also determine seven pathogen-specific oligonucleotides by a single chip containing both positive and negative controls.

A Portable Analyzer for Pouch-Actuated, Immunoassay Cassettes

PubMed Central

Qiu, Xianbo; Liu, Changchun; Mauk, Michael G.; Hart, Robert W.; Chen, Dafeng; Qiu, Jing; Kientz, Terry; Fiene, Jonathan; Bau, Haim H.

2011-01-01

A portable, small footprint, light, general purpose analyzer (processor) to control the flow in immunoassay cassettes and to facilitate the detection of test results is described. The durable analyzer accepts disposable cassettes that contain pouches and reaction chambers for various unit operations such as hydration of dry reagents, stirring, and incubation. The analyzer includes individually controlled, linear actuators to compress the pouches in the cassette, which facilitates the pumping and mixing of sample and reagents, and to close diaphragm-based valves for flow control. The same types of actuators are used to compress pouches and actuate valves. The analyzer also houses a compact OEM scanner/reader to excite fluorescence and detect emission from labels. The analyzer is hydraulically isolated from the cassette, reducing the possibility of cross-contamination. The analyzer facilitates programmable, automated execution of a sequence of operations such as pumping and valving in a timely fashion, reducing the level of expertise required from the operator and the possibility for errors. The analyzer’s design is modular and expandable to accommodate cassettes of various complexities and additional functionalities. In this paper, the utility of the analyzer has been demonstrated with the execution of a simple, consecutive, lateral flow assay of a model biological system and the test results were detected with up converting phosphor labels that are excited at infrared frequencies and emit in the visible spectrum. PMID:22125359

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor.

PubMed

Xiao, Wei; Xiao, Meng; Fu, Qiangqiang; Yu, Shiting; Shen, Haicong; Bian, Hongfen; Tang, Yong

2016-11-08

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg 2+ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg 2+ , which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg 2+ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg 2+ concentration in the range of 1 ng/mL-32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg 2+ . The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment.

A Portable Smart-Phone Readout Device for the Detection of Mercury Contamination Based on an Aptamer-Assay Nanosensor

PubMed Central

Xiao, Wei; Xiao, Meng; Fu, Qiangqiang; Yu, Shiting; Shen, Haicong; Bian, Hongfen; Tang, Yong

2016-01-01

The detection of environmental mercury (Hg) contamination requires complex and expensive instruments and professional technicians. We present a simple, sensitive, and portable Hg2+ detection system based on a smartphone and colorimetric aptamer nanosensor. A smartphone equipped with a light meter app was used to detect, record, and process signals from a smartphone-based microwell reader (MR S-phone), which is composed of a simple light source and a miniaturized assay platform. The colorimetric readout of the aptamer nanosensor is based on a specific interaction between the selected aptamer and Hg2+, which leads to a color change in the reaction solution due to an aggregation of gold nanoparticles (AuNPs). The MR S-phone-based AuNPs-aptamer colorimetric sensor system could reliably detect Hg2+ in both tap water and Pearl River water samples and produced a linear colorimetric readout of Hg2+ concentration in the range of 1 ng/mL–32 ng/mL with a correlation of 0.991, and a limit of detection (LOD) of 0.28 ng/mL for Hg2+. The detection could be quickly completed in only 20 min. Our novel mercury detection assay is simple, rapid, and sensitive, and it provides new strategies for the on-site detection of mercury contamination in any environment. PMID:27834794

Low-cost chlorophyll meter (LCCM): portable measuring device for leaf chlorophyll

NASA Astrophysics Data System (ADS)

Hutomo E. P., Evan; Adibawa, Marcelinus Alfasisurya S.; Prilianti, Kestrilia R.; Heriyanto, Heriyanto; Brotosudarmo, Tatas H. P.

2016-11-01

Portable leaf chlorophyll meter, named low-cost chlorophyll meter (LCCM), has been created. This device was created to help farmer determining the health condition of plant based on the greenness level of leaf surface. According to previous studies, leaf greenness with a certain amount of chlorophyll level has a direct correlation with the amount of nitrogen in the leaf that indicates health of the plant and this fact needed to provide an estimate of further measures to keep the plants healthy. Device that enables to measure the leaf color change is soil plant analysis development (SPAD) meter 502 from Konica Minolta but it is relatively expensive. To answer the need of low-cost chlorophyll scanner device, this research conducted experiment using light reflectance as the base mechanism. Reflectance system from LCCM consists of near-infrared light emitting diode (LED) and red LED as light resources and photodiode. The output from both of light resources calculated using normalized difference vegetation index (NDVI) formula as the results fetched and displayed on the smartphone application using Bluetooth communication protocol. Finally, the scanner has been made as well as the Android application named NDVI Reader. The LCCM system which has been tested on 20 sample of cassava leaf with SPAD meter as a variable control showed coefficient of determination 0.9681 and root-mean-square error (RMSE) 0.014.

Hardware Architecture for Measurements for 50-V Battery Modules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patrick Bald; Evan Juras; Jon P. Christophersen

Energy storage devices, especially batteries, have become critical for several industries including automotive, electric utilities, military and consumer electronics. With the increasing demand for electric and hybrid electric vehicles and the explosion in popularity of mobile and portable electronic devices such as laptops, cell phones, e-readers, tablet computers and the like, reliance on portable energy storage devices such as batteries has likewise increased. Because many of the systems these batteries integrated into are critical, there is an increased need for an accurate in-situ method of monitoring battery state-of-health. Over the past decade the Idaho National Laboratory (INL), Montana Tech ofmore » the University of Montana (Tech), and Qualtech Systems, Inc. (QSI) have been developing the Smart Battery Status Monitor (SBSM), an integrated battery management system designed to monitor battery health, performance and degradation and use this knowledge for effective battery management and increased battery life. Key to the success of the SBSM is an in-situ impedance measurement system called the Impedance Measurement Box (IMB). One of the challenges encountered has been development of a compact IMB system that will perform rapid accurate measurements of a battery impedance spectrum working with higher voltage batteries of up to 300 volts. This paper discusses the successful realization of a system that will work up to 50 volts.« less

Miniaturised wireless smart tag for optical chemical analysis applications.

PubMed

Steinberg, Matthew D; Kassal, Petar; Tkalčec, Biserka; Murković Steinberg, Ivana

2014-01-01

A novel miniaturised photometer has been developed as an ultra-portable and mobile analytical chemical instrument. The low-cost photometer presents a paradigm shift in mobile chemical sensor instrumentation because it is built around a contactless smart card format. The photometer tag is based on the radio-frequency identification (RFID) smart card system, which provides short-range wireless data and power transfer between the photometer and a proximal reader, and which allows the reader to also energise the photometer by near field electromagnetic induction. RFID is set to become a key enabling technology of the Internet-of-Things (IoT), hence devices such as the photometer described here will enable numerous mobile, wearable and vanguard chemical sensing applications in the emerging connected world. In the work presented here, we demonstrate the characterisation of a low-power RFID wireless sensor tag with an LED/photodiode-based photometric input. The performance of the wireless photometer has been tested through two different model analytical applications. The first is photometry in solution, where colour intensity as a function of dye concentration was measured. The second is an ion-selective optode system in which potassium ion concentrations were determined by using previously well characterised bulk optode membranes. The analytical performance of the wireless photometer smart tag is clearly demonstrated by these optical absorption-based analytical experiments, with excellent data agreement to a reference laboratory instrument. © 2013 Elsevier B.V. All rights reserved.

Medically relevant assays with a simple smartphone and tablet based fluorescence detection system.

PubMed

Wargocki, Piotr; Deng, Wei; Anwer, Ayad G; Goldys, Ewa M

2015-05-20

Cell phones and smart phones can be reconfigured as biomedical sensor devices but this requires specialized add-ons. In this paper we present a simple cell phone-based portable bioassay platform, which can be used with fluorescent assays in solution. The system consists of a tablet, a polarizer, a smart phone (camera) and a box that provides dark readout conditions. The assay in a well plate is placed on the tablet screen acting as an excitation source. A polarizer on top of the well plate separates excitation light from assay fluorescence emission enabling assay readout with a smartphone camera. The assay result is obtained by analysing the intensity of image pixels in an appropriate colour channel. With this device we carried out two assays, for collagenase and trypsin using fluorescein as the detected fluorophore. The results of collagenase assay with the lowest measured concentration of 3.75 µg/mL and 0.938 µg in total in the sample were comparable to those obtained by a microplate reader. The lowest measured amount of trypsin was 930 pg, which is comparable to the low detection limit of 400 pg for this assay obtained in a microplate reader. The device is sensitive enough to be used in point-of-care medical diagnostics of clinically relevant conditions, including arthritis, cystic fibrosis and acute pancreatitis.

A portable optical reader and wall projector towards enumeration of bio-conjugated beads or cells

PubMed Central

McArdle, Niamh A.; Kendlin, Jane L.; O’Connell, Triona M.; Ducrée, Jens

2017-01-01

Measurement of the height of a packed column of cells or beads, which can be direclty related to the number of cells or beads present in a chamber, is an important step in a number of diagnostic assays. For example, haematocrit measurements may rapidly identify anemia or polycthemia. Recently, user-friendly and cost-efficient Lab-on-a-Chip devices have been developed towards isolating and counting cell sub-populations for diagnostic purposes. In this work, we present a low-cost optical module for estimating the filling level of packed magnetic beads within a Lab-on-a-Chip device. The module is compatible with a previously introduced, disposable microfluidic chip for rapid determination of CD4+ cell counts. The device is a simple optical microscope module is manufactured by 3D printing. An objective lens directly interrogates the height of packed beads which are efficiently isolated on the finger-actuated chip. Optionally, an inexpensive, battery-powered Light Emitting Diode may project a shadow of the microfluidic chip at approximately 50-fold magnification onto a nearby surface. The reader is calibrated with the filling levels of known concentrations of paramagnetic beads within the finger actuated chip. Results in direct and projector mode are compared to measurements from a conventional, inverted white-light microscope. All three read-out methods indicate a maximum variation of 6.5% between methods. PMID:29267367

Assigning sex and reproductive stage to adult Lake Sturgeon using ultrasonography and common morphological measurements

USGS Publications Warehouse

Chiotti, Justin A.; Boase, James C.; Hondorp, Darryl W.; Briggs, Andrew S.

2016-01-01

Sex determination of fish species is difficult to assess when sexual dimorphism and gametes are not apparent. For threatened and endangered fish species, noninvasive techniques are needed when determining sex to minimize stress and the potential for mortality. We evaluated the use of a portable ultrasound unit to determine sex of Lake Sturgeon Acipenser fulvescens in the field. Ultrasound images were collected from 9 yellow-egg (F2, F3), 32 black-egg (F4, F5), and 107 fully developed male (M2) Lake Sturgeon. Two readers accurately assigned sex to 88–96% of fish, but accuracy varied in relation to maturity stage. Black-egg females and fully developed males were correctly identified for 89–100% of the fish sampled, while these two readers identified yellow-egg females only 33% and 67% of the time. Time spent collecting images ranged between 2 and 3 min once the user was comfortable with operating procedures. Discriminant analysis revealed the total length : girth ratio was a strong predictor of sex and maturity, correctly classifying 81% of black-egg females and 97% of the fully developed males. However, yellow-egg females were incorrectly classified on all occasions. This study shows the utility of using ultrasonography and a total length : girth ratio for sex determination of Lake Sturgeon in later reproductive stages around the spawning season.

Single-Grain OSL Dating of Early Middle Palaeolithic Deposits at Cuesta de la Bajada, Ebro Basin, Spain

NASA Astrophysics Data System (ADS)

Arnold, L. J.; Demuro, M.; Santonja, M.; Perez-Gonzalez, A.

2012-12-01

The open-air site of Cuesta de la Bajada comprises a 2-2.5 m-thick sequence of fluvial-lacustrine sediments inset into the +50-60 m terrace deposits preserved along the south-eastern margins of the Alfambra river valley, Teruel, Spain. The main archaeological horizons lie ~20 m above the present-day river level and consists of an upward-fining sequence of massive fluvial silts and fine sands with dispersed gravels, detritic marls and shales that collectively overlie a series of planar bedded fluvial gravels. These units have yielded ~3000 lithic artefacts displaying reduction techniques characteristic of an early Middle Palaeolithic techno-complex, as well as a multitude of faunal remains indicative of a late Middle Pleistocene origin. The paucity of open-air Palaeolithic sites in the interior eastern sector of the Iberian Peninsula, and the relatively low number of documented early Middle Palaeolithic archives in this region, means that Cuesta de la Bajada is of key importance for understanding the coexistence/transition of Iberian Acheulean and Mousterian techno-complexes during the Middle Pleistocene period. Establishing reliable absolute chronologies at Cuesta de la Bajada remains essential for understanding the regional significance of this site. In an attempt to redress the existing chronological uncertainty we are undertaking an interdisciplinary dating study of the Middle Palaeolithic deposits using OSL dating, ESR/U-series dating of teeth and ESR dating of sedimentary quartz. Here we present results obtained using quartz single-grain OSL dating of 4 samples collected from a 7 m vertical profile bracketing the archaeological horizons. 2 samples were collected from the archaeology-bearing silt and fine sand horizons, while the remaining samples were obtained from well-bedded fine-sands and silts 3.5 m above and 3 m below the main excavation. The measured quartz grains are characterised by relatively bright OSL signals and typically display dose-response curves with very high saturation limits. The latter offers the advantage of extending the age range over which single-grain techniques can be applied in this Middle Pleistocene context. Dose-recovery tests performed at high doses of 470 Gy yielded accurate equivalent dose (De) results with low overdispersion, providing reasonable confidence in the chosen measurement conditions. 3 of the samples display single-grain De distributions with low levels of dispersion indicating that the sediments were adequately bleached prior to burial and remained undisturbed thereafter. The fourth sample displays higher De dispersion and a younger subpopulation of grains, which could be explained by beta-dose heterogeneity associated with interspersed gravels within the basal archaeological horizon. We apply various statistical age models to derive final chronologies and compare the resultant single-grain ages with those obtained using different absolute dating methods. We also report on experiments performed using 'synthetic multi-grain aliquots' created from the single-grain De datasets, and discuss their implications for the reliability of multi-grain OSL dating techniques in this context.

Single-grain OSL dating of Early Middle Palaeolithic deposits at Cuesta de la Bajada, Ebro Basin, Spain

NASA Astrophysics Data System (ADS)

Arnold, Lee; Demuro, Martina; Santonja, Manuel; Perez-Gonzalez, Alfredo; Pares, Josep

2013-04-01

The open-air site of Cuesta de la Bajada comprises a 2-2.5 m-thick sequence of fluvial-lacustrine sediments inset into the +50-60 m terrace deposits preserved along the south-eastern margins of the Alfambra river valley, Teruel, Spain. The main archaeological horizons lie ~20 m above the present-day river level and consists of an upward-fining sequence of massive fluvial silts and fine sands with dispersed gravels, detritic marls and shales that collectively overlie a series of planar bedded fluvial gravels. These units have yielded ~3000 lithic artefacts displaying reduction techniques characteristic of an early Middle Palaeolithic techno-complex, as well as a multitude of faunal remains indicative of a late Middle Pleistocene origin. The paucity of open-air Palaeolithic sites in the interior eastern sector of the Iberian Peninsula, and the relatively low number of documented early Middle Palaeolithic archives in this region, means that Cuesta de la Bajada is of key importance for understanding the coexistence/transition of Iberian Acheulean and Mousterian techno-complexes during the Middle Pleistocene period. Establishing reliable absolute chronologies at Cuesta de la Bajada remains essential for understanding the regional significance of this site. In an attempt to redress the existing chronological uncertainty we are undertaking an interdisciplinary dating study of the Middle Palaeolithic deposits using OSL dating, ESR/U-series dating of teeth and ESR dating of sedimentary quartz. Here we present results obtained using quartz single-grain OSL dating of 4 samples collected from a 7 m vertical profile bracketing the archaeological horizons. 2 samples were collected from the archaeology-bearing silt and fine sand horizons, while the remaining samples were obtained from well-bedded fine-sands and silts 3.5 m above and 3 m below the main excavation. The measured quartz grains are characterised by relatively bright OSL signals and typically display dose-response curves with very high saturation limits. The latter offers the advantage of extending the age range over which single-grain techniques can be applied in this Middle Pleistocene context. Dose-recovery tests performed at high doses of 470 Gy yielded accurate equivalent dose (De) results with low overdispersion, providing reasonable confidence in the chosen measurement conditions. Three of the samples display single-grain De distributions with low levels of dispersion indicating that the sediments were adequately bleached prior to burial and remained undisturbed thereafter. The fourth sample displays higher De dispersion and a younger subpopulation of grains, which could be explained by beta-dose heterogeneity associated with interspersed gravels within the basal archaeological horizon. We apply various statistical age models to derive final chronologies and compare the resultant single-grain ages with those obtained using different absolute dating methods. We also report on experiments performed using 'synthetic multi-grain aliquots' created from the single-grain De datasets, and discuss their implications for the reliability of multi-grain OSL dating techniques in this context.

MEASUREMENT OF RADIATION DOSES TO THE EYE LENS DURING ORTHOPEDIC SURGERY USING AN C-ARM X-RAY SYSTEM.

PubMed

Suzuki, Akira; Matsubara, Kosuke; Sasa, Yuko

2018-04-01

The present study aimed to determine doses delivered to the eye lenses of surgeons while using the inverted-C-arm technique and the protective effect of leaded spectacles during orthopedic surgery. The kerma in air was measured at five positions on leaded glasses positioned near the eye lens and on the neck using small optically stimulated luminescence (OSL) dosemeters. The lens equivalent dose was also measured at the neck using an OSL dosemeter. The maximum equivalent dose to the eye lens and the maximum kerma were 0.8 mSv/month and 0.66 mGy/month, respectively. The leaded glasses reduced the exposure by ~60%. Even if the surgeons are exposed to the maximum dose of X-ray radiation for 5 years, the equivalent doses to the eye lens will not exceed the present limit recommended by the ICRP.

Synthesis and characterization of luminescent materials for thermal sensing and proton dosimetry

NASA Astrophysics Data System (ADS)

Doull, Brandon Arthur

The work presented in this thesis is the materials synthesis, investigation of synthesis parameters, and basic luminescent characterizations of MgB 4O7, Li2B4O7, and MgO for the applications of thermal sensing using thermoluminescence (TL) and proton dosimetry using optically stimulated luminescence (OSL). The materials were synthesized using solution combustion synthesis and characterized by x-ray diffraction, radioluminescence, thermoluminescence, and optically stimulated luminescence. Based upon the basic characterizations MgB 4O7:Li,Dy and Li2B4O7:Cu,Ag were selected for their potential for use as TL materials for thermal sensing while MgB4O7:Li,Ce and MgO:Li were chosen for use as OSL materials in proton dosimetry. Furthermore, MgB4O7:Li,Ce and MgO:Li were fabricated into detector assemblies and exposed to a clinical proton beam for analysis.

Development and validation of a GEANT4 radiation transport code for CT dosimetry

PubMed Central

Carver, DE; Kost, SD; Fernald, MJ; Lewis, KG; Fraser, ND; Pickens, DR; Price, RR; Stabin, MG

2014-01-01

We have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate our simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air, a standard 16-cm acrylic head phantom, and a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of our Monte Carlo simulations. We found that simulated and measured CTDI values were within an overall average of 6% of each other. PMID:25706135

Study of radiation induced effects in the luminescence of nanostructured Al2O3: Yb, Er crystals

NASA Astrophysics Data System (ADS)

Gonçalves, K. A.; Bitencourt, J. F. S.; Mittani, J. C. R.; Tatumi, S. H.

2010-11-01

Alumina crystals doped with Yb and Er were obtained by sol gel process and their morphologies and luminescence properties were discussed. Nanocrystals formations composed by Er2O3, Yb2O3 e Yb3Al5O12 were observed by TEM images, EDS, electron beam diffraction and XRD, at the surface of the alumina grains. The size of the nanocrystals were of about (36±2) nm and (182±8) nm for the samples calcinated at 1200oC and 1600oC, respectively. The sample codoped with 1mol% of Er and 2 mol% of Yb supplied the best results for Thermoluminescence (TL) and Optically Stimulated Luminescence (OSL). The growth intensity of dosimetric TL peak at 205oC was linear with gamma radiation doses and the same behavior was observed in OSL results.

Development and validation of a GEANT4 radiation transport code for CT dosimetry.

PubMed

Carver, D E; Kost, S D; Fernald, M J; Lewis, K G; Fraser, N D; Pickens, D R; Price, R R; Stabin, M G

2015-04-01

The authors have created a radiation transport code using the GEANT4 Monte Carlo toolkit to simulate pediatric patients undergoing CT examinations. The focus of this paper is to validate their simulation with real-world physical dosimetry measurements using two independent techniques. Exposure measurements were made with a standard 100-mm CT pencil ionization chamber, and absorbed doses were also measured using optically stimulated luminescent (OSL) dosimeters. Measurements were made in air with a standard 16-cm acrylic head phantom and with a standard 32-cm acrylic body phantom. Physical dose measurements determined from the ionization chamber in air for 100 and 120 kVp beam energies were used to derive photon-fluence calibration factors. Both ion chamber and OSL measurement results provide useful comparisons in the validation of the Monte Carlo simulations. It was found that simulated and measured CTDI values were within an overall average of 6% of each other.

An optical age chronology of late Quaternary extreme fluvial events recorded in Ugandan dambo soils

USGS Publications Warehouse

Mahan, S.A.; Brown, D.J.

2007-01-01

There is little geochonological data on sedimentation in dambos (seasonally saturated, channel-less valley floors) found throughout Central and Southern Africa. Radiocarbon dating is problematic for dambos due to (i) oxidation of organic materials during dry seasons; and (ii) the potential for contemporary biological contamination of near-surface sediments. However, for luminescence dating the equatorial site and semi-arid climate facilitate grain bleaching, while the gentle terrain ensures shallow water columns, low turbidity, and relatively long surface exposures for transported grains prior to deposition and burial. For this study, we focused on dating sandy strata (indicative of high-energy fluvial events) at various positions and depths within a second-order dambo in central Uganda. Blue-light quartz optically stimulated luminescences (OSL) ages were compared with infrared stimulated luminescence (IRSL) and thermoluminescence (TL) ages from finer grains in the same sample. A total of 8 samples were dated, with 6 intervals obtained at ???35, 33, 16, 10.4, 8.4, and 5.9 ka. In general, luminescence ages were stratigraphically, geomorphically and ordinally consistent and most blue-light OSL ages could be correlated with well-dated climatic events registered either in Greenland ice cores or Lake Victoria sediments. Based upon OSL age correlations, we theorize that extreme fluvial dambo events occur primarily during relatively wet periods, often preceding humid-to-arid transitions. The optical ages reported in this study provide the first detailed chronology of dambo sedimentation, and we anticipate that further dambo work could provide a wealth of information on the paleohydrology of Central and Southern Africa. ?? 2006 Elsevier Ltd. All rights reserved.

Palaeoclimatic implications of aeolian sediments on the Miaodao Islands, Bohai Sea, East China, based on OSL dating and proxies

NASA Astrophysics Data System (ADS)

Xu, Shujian; Ding, Xinchao; Yu, Lupeng; Ni, Zhichao

2015-12-01

The loess-paleosol sequences in Shandong Province, East China, is an important aeolian archive, which can provide information for aeolian activity, palaeoclimatic change and sea level change in eastern coast of China since the last interglacial period. However, for so long, most of the studies about loess have been focused on the Chinese Loess Plateau, remaining many questions and disputes about the loess in East China. The Xianjingyuan (XJY) section on the TIA, Bohai Sea, is a representative aeolian section for islands off the eastern coast of China. In this study, optically stimulated luminescence (OSL) dating, particle size and magnetic susceptibility were applied to date and analysis the loess-paleosol sequences in this section. The results show that: (1) The OSL ages at the depths of 0.8 m, 2.5 m, and 3.9 m are 12.6 ± 1.0 ka, 19.2 ± 1.1 ka and 56.9 ± 2.6 ka, respectively, and the loess started to accumulate at ca. 86.5 ka according to the depositional rates (2) The loess accumulated mainly during the Marine Isotope Stage (MIS) 2, i.e., Last glacial maximum and deglaciation, MIS4 and MIS3b with higher depositional rate, coarser grain size, and higher magnetic susceptibility; while paleosol mainly developed during MIS3a, MIS3c and MIS5 with lower depositional rate, finer grain size and lower magnetic susceptibility. (3) The palaeoclimatic changes and aeolian sediments evolution were mainly controlled by the changes of East Asian summer monsoon and sea levels.

Optical dating of eolian deposits since the last interglacial along the northern margin of the Chinese Loess Plateau

NASA Astrophysics Data System (ADS)

Lü, Tongyan; Sun, Jimin; Gong, Zhijun

2018-04-01

Understanding the chronology of eolian sand-loess-paleosol sequences along the northern margin of the Chinese Loess Plateau (CLP) is crucial for comprehending climate change and the advance and retreat of the adjacent Mu Us desert. In this study, a sand-loess-soil sequence from the northern margin of the CLP was studied by applying the single aliquot regenerative (SAR) protocol to quartz grains, and the multi-elevated-temperature post-IR IRSL (MET-pIRIR) protocol to K-feldspar grains. For equivalent dose (De) determination, 63-90 μm quartz and K-feldspar grains were used. Our results indicate that the MET-pIRIR ages of K-feldspar grains in this sequence range from 94.4 ± 7.0 ka to 148.3 ± 13.3 ka for the last interglacial paleosol (S1); for the upper part of the section, quartz-based SAR-OSL dating was used, yielding ages spanning from 5.8 ± 0.4 ka to 35.9 ± 4.1 ka. After cross-checking these results with previously-reported isochron OSL and TL ages, the reliability of the MET-pIRIR protocol when applied to the last interglacial paleosol was confirmed. Based on a new OSL chronology of the Shimao profile, the studied eolian deposits can be broadly correlated with the last glacial-interglacial cycle, but their dating also points to sedimentary hiatuses occurring at 94.4 ka, 35.9 ka and 5.8 ka, due most probably to strong wind erosion caused by intensified cold-dry winter monsoonal circulations during the last glacial maxima.

Characterization of a fiber-coupled Al2O3:C luminescence dosimetry system for online in vivo dose verification during 192Ir brachytherapy.

PubMed

Andersen, Claus E; Nielsen, Søren Kynde; Greilich, Steffen; Helt-Hansen, Jakob; Lindegaard, Jacob Christian; Tanderup, Kari

2009-03-01

A prototype of a new dose-verification system has been developed to facilitate prevention and identification of dose delivery errors in remotely afterloaded brachytherapy. The system allows for automatic online in vivo dosimetry directly in the tumor region using small passive detector probes that fit into applicators such as standard needles or catheters. The system measures the absorbed dose rate (0.1 s time resolution) and total absorbed dose on the basis of radioluminescence (RL) and optically stimulated luminescence (OSL) from aluminum oxide crystals attached to optical fiber cables (1 mm outer diameter). The system was tested in the range from 0 to 4 Gy using a solid-water phantom, a Varian GammaMed Plus 192Ir PDR afterloader, and dosimetry probes inserted into stainless-steel brachytherapy needles. The calibrated system was found to be linear in the tested dose range. The reproducibility (one standard deviation) for RL and OSL measurements was 1.3%. The measured depth-dose profiles agreed well with the theoretical expectations computed with the EGSNRC Monte Carlo code, suggesting that the energy dependence for the dosimeter probes (relative to water) is less than 6% for source-to-probe distances in the range of 2-50 mm. Under certain conditions, the RL signal could be greatly disturbed by the so-called stem signal (i.e., unwanted light generated in the fiber cable upon irradiation). The OSL signal is not subject to this source of error. The tested system appears to be adequate for in vivo brachytherapy dosimetry.

The chronology of Late Pleistocene thermal contraction cracking derived from sand wedge OSL dating in central and southern France

NASA Astrophysics Data System (ADS)

Andrieux, Eric; Bateman, Mark D.; Bertran, Pascal

2018-03-01

Much of France remained unglaciated during the Late Quaternary and was subjected to repeated phases of periglacial activity. Numerous periglacial features have been reported but disentangling the environmental and climatic conditions they formed under, the timing and extent of permafrost and the role of seasonal frost has remained elusive. The primary sandy infillings of relict sand-wedges and composite-wedge pseudomorphs record periglacial activity. As they contain well-bleached quartz-rich aeolian material they are suitable for optically stimulated luminescence dating (OSL). This study aims to reconstruct when wedge activity took place in two regions of France; Northern Aquitaine and in the Loire valley. Results from single-grain OSL measurements identify multiple phases of activity within sand wedges which suggest that wedge activity in France occurred at least 11 times over the last 100 ka. The most widespread events of thermal contraction cracking occurred between ca. 30 and 24 ka (Last Permafrost Maximum) which are concomitant with periods of high sand availability (MIS 2). Although most phases of sand-wedge growth correlate well with known Pleistocene cold periods, the identification of wedge activity during late MIS 5 and the Younger Dryas strongly suggests that these features do not only indicate permafrost but also deep seasonal ground freezing in the context of low winter insolation. These data also suggest that the overall young ages yielded by North-European sand-wedges likely result from poor record of periglacial periods concomitant with low sand availability and/or age averaging inherent with standard luminescence methods.

Development and demonstration of 2D dosimetry using optically stimulated luminescence from new Al2O3 films for radiotherapy applications

NASA Astrophysics Data System (ADS)

Ahmed, Md Foiez

Scope and Method of Study: The goal of this work was to develop and demonstrate a 2D dosimetry system based on the optically stimulated luminescence (OSL) from new Al2O3 films for radiotherapy applications. A 2D laser-scanning system was developed for the readout and two OSL films (Al2O3:C and Al2O3:C,Mg) were tested. A dose reconstruction algorithm addressing corrections required for the characteristic material properties and the properties related to the system design was developed. The dosimetric properties of the system were tested using clinical X-ray (6 MV) beam. The feasibility of small field dosimetry was tested using heavy ion beams (221 MeV proton and 430 MeV 12C beam). For comparison, clinical tests were performed with ionization chamber, diode arrays and the commercial radiochromic films (Gafchromic EBT3) when applicable. Findings and Conclusions: The results demonstrate that the developed image reconstruction algorithm enabled > 300x faster laser-scanning readout of the Al2O3 films, eliminating the restriction imposed by its slow luminescence decay. The algorithm facilitates submillimeter spatial resolution, reduces the scanner position dependence (of light collection efficiency) and removes the inherent galvo geometric distortion, among other corrections. The system has a background signal < 1 mGy, linearity correction factor of < 10% up to ˜4.0 Gy and < 2% dose uncertainty over the clinically relevant dose range of 0.1 - 30 Gy. The system has a dynamic range of 4 - 5 orders, only limited by PMT linearity. The absolute response from Al2O2:C films is higher than Al2O 2:C,Mg films, but with lower image signal-to-noise ratio due to lower concentration of fast F+-center emission. As a result, Al2O2:C,Mg films are better suited than Al2O3:C films for small field dosimetry, which requires precise dosimetry with sub-millimeter spatial resolution. The dose uncertainty associated with OSL film dosimetry is lower than that associated with EBT3 film dosimetry due to lower background, simpler calibration and wider dynamic range. In conclusion, this work demonstrates excellent potentials of the 2D OSL dosimetry system for both relative and absolute dosimetry in radiotherapy applications, with especial emphasis on small fields.

Development of direct dating methods of fault gouges: Deep drilling into Nojima Fault, Japan

NASA Astrophysics Data System (ADS)

Miyawaki, M.; Uchida, J. I.; Satsukawa, T.

2017-12-01

It is crucial to develop a direct dating method of fault gouges for the assessment of recent fault activity in terms of site evaluation for nuclear power plants. This method would be useful in regions without Late Pleistocene overlying sediments. In order to estimate the age of the latest fault slip event, it is necessary to use fault gouges which have experienced high frictional heating sufficient for age resetting. It is said that frictional heating is higher in deeper depths, because frictional heating generated by fault movement is determined depending on the shear stress. Therefore, we should determine the reliable depth of age resetting, as it is likely that fault gouges from the ground surface have been dated to be older than the actual age of the latest fault movement due to incomplete resetting. In this project, we target the Nojima fault which triggered the 1995 Kobe earthquake in Japan. Samples are collected from various depths (300-1,500m) by trenching and drilling to investigate age resetting conditions and depth using several methods including electron spin resonance (ESR) and optical stimulated luminescence (OSL), which are applicable to ages later than the Late Pleistocene. The preliminary results by the ESR method show approx. 1.1 Ma1) at the ground surface and 0.15-0.28 Ma2) at 388 m depth, respectively. These results indicate that samples from deeper depths preserve a younger age. In contrast, the OSL method dated approx. 2,200 yr1) at the ground surface. Although further consideration is still needed as there is a large margin of error, this result indicates that the age resetting depth of OSL is relatively shallow due to the high thermosensitivity of OSL compare to ESR. In the future, we plan to carry out further investigation for dating fault gouges from various depths up to approx. 1,500 m to verify the use of these direct dating methods.1) Kyoto University, 2017. FY27 Commissioned for the disaster presentation on nuclear facilities (Drilling borehole survey at the Nojima fault), Technical Report. (in Japanese)2) T. Fukuchi, 2001, Assessment of fault activity by ESR dating of fault gouge; an example of the 500m core samples drilled into the Nojima Earthquake Fault in Japan. Quaternary Science Reviews, 20, 1005-1008.

Chronostratigraphic Analysis of Geomorphic Features within the Former Sinepuxent Inlet: A Wave-Dominated Tidal Inlet along Assateague Island, MD, USA

NASA Astrophysics Data System (ADS)

Seminack, C.; McBride, R.; Petruny, L. M.

2017-12-01

The former Sinepuxent Inlet, located along the mixed-energy, wave-dominated Assateague Island, MD-VA, USA, contains some of the most robust recurved-spit ridges along the span of the barrier island. In addition, this former tidal inlet exhibits a poorly developed flood-tidal delta containing at least two sets of curvilinear ridges known as "washarounds". Historical maps and nautical charts indicate that the former Sinepuxent Inlet was open from 1755 to 1832. However, previous studies conducted at the former Sinepuxent Inlet hypothesized that the site was exposed to episodic breaching events because of the extensive width of the former inlet throat, constrained by the northern and southern recurved-spit ridges. A total of 16 sediment cores, 10 optically stimulated luminescence (OSL) samples, and three 14C samples (mixed benthic foraminifera and eastern mud snail [Ilyanassa obsolete]) were collected from the former Sinepuxent Inlet to place morphostratigraphic units into a chronological context. Six OSL samples were collected from the northern and southern recurved-spit ridges at mean sea level (MSL) to constrain genesis ages. Southern recurved-spit ages varied more than their northern counterparts, ranging from 1640 to 1990 AD. The northern recurved-spit ridges varied in age from 1770 to 1900 AD. Two OSL samples collected from flood-tidal delta ridges yielded ages from 1680 to 2000 AD. In addition, two 14C samples collected at 128 and 101 cm below MSL within the inlet throat yielded ages between 1720 and post-1950 AD. Ultimately, these dates overlap with the inlet activity phase as indicated in historical documents. Conversely, two OSL samples (155 and 201 cm below MSL) and one 14C sample (134 cm below MSL) collected from the inlet throat returned ages between 760 and 1465 AD. The contrast in ages between the older inlet throat and subaerial ridge samples supports the hypothesis that the former Sinepuxent Inlet was reactivated numerous times. Thus, the three age groupings of geomorphic features (1. older inlet throat, 2. southern recurved-spit ridges & flood-tidal delta ridges, and 3. northern recurved-spit ridges & younger inlet throat) at the former Sinepuxent Inlet likely record the response of Assateague Island to at least three intense storms over the past 1,200 years.

Design and implementation of relational databases relevant to the diverse needs of a tuberculosis case contact study in the Gambia.

PubMed

Jeffries, D J; Donkor, S; Brookes, R H; Fox, A; Hill, P C

2004-09-01

The data requirements of a large multidisciplinary tuberculosis case contact study are complex. We describe an ACCESS-based relational database system that meets our rigorous requirements for data entry and validation, while being user-friendly, flexible, exportable, and easy to install on a network or stand alone system. This includes the development of a double data entry package for epidemiology and laboratory data, semi-automated entry of ELISPOT data directly from the plate reader, and a suite of new programmes for the manipulation and integration of flow cytometry data. The double entered epidemiology and immunology databases are combined into a separate database, providing a near-real-time analysis of immuno-epidemiological data, allowing important trends to be identified early and major decisions about the study to be made and acted on. This dynamic data management model is portable and can easily be applied to other studies.

Effectively incorporating selected multimedia content into medical publications

PubMed Central

2011-01-01

Until fairly recently, medical publications have been handicapped by being restricted to non-electronic formats, effectively preventing the dissemination of complex audiovisual and three-dimensional data. However, authors and readers could significantly profit from advances in electronic publishing that permit the inclusion of multimedia content directly into an article. For the first time, the de facto gold standard for scientific publishing, the portable document format (PDF), is used here as a platform to embed a video and an audio sequence of patient data into a publication. Fully interactive three-dimensional models of a face and a schematic representation of a human brain are also part of this publication. We discuss the potential of this approach and its impact on the communication of scientific medical data, particularly with regard to electronic and open access publications. Finally, we emphasise how medical teaching can benefit from this new tool and comment on the future of medical publishing. PMID:21329532

PACS-Based Computer-Aided Detection and Diagnosis

NASA Astrophysics Data System (ADS)

Huang, H. K. (Bernie); Liu, Brent J.; Le, Anh HongTu; Documet, Jorge

The ultimate goal of Picture Archiving and Communication System (PACS)-based Computer-Aided Detection and Diagnosis (CAD) is to integrate CAD results into daily clinical practice so that it becomes a second reader to aid the radiologist's diagnosis. Integration of CAD and Hospital Information System (HIS), Radiology Information System (RIS) or PACS requires certain basic ingredients from Health Level 7 (HL7) standard for textual data, Digital Imaging and Communications in Medicine (DICOM) standard for images, and Integrating the Healthcare Enterprise (IHE) workflow profiles in order to comply with the Health Insurance Portability and Accountability Act (HIPAA) requirements to be a healthcare information system. Among the DICOM standards and IHE workflow profiles, DICOM Structured Reporting (DICOM-SR); and IHE Key Image Note (KIN), Simple Image and Numeric Report (SINR) and Post-processing Work Flow (PWF) are utilized in CAD-HIS/RIS/PACS integration. These topics with examples are presented in this chapter.

Tabular data and graphical images in support of the U.S. Geological Survey National Oil and Gas Assessment--San Juan Basin Province (5022): Chapter 7 in Total petroleum systems and geologic assessment of undiscovered oil and gas resources in the San Juan Basin Province, exclusive of Paleozoic rocks, New Mexico and Colorado

USGS Publications Warehouse

Klett, T.R.; Le, P.A.

2013-01-01

This chapter describes data used in support of the process being applied by the U.S. Geological Survey (USGS) National Oil and Gas Assessment (NOGA) project. Digital tabular data used in this report and archival data that permit the user to perform further analyses are available elsewhere on this CD–ROM. Computers and software may import the data without transcription from the Portable Document Format files (.pdf files) of the text by the reader. Because of the number and variety of platforms and software available, graphical images are provided as .pdf files and tabular data are provided in a raw form as tab-delimited text files (.tab files).

SCIMITAR: subject-carried implant monitoring inductive telemetric ambulatory reader for remote data acquisition from implanted orthopaedic prostheses.

PubMed

Hao, Shiying; Gorjon, Jose; Taylor, Stephen

2014-03-01

This work describes the functions of the external, portable part of a telemetry system for powering and interrogating implantable electrical devices built within orthopaedic implants for real-time data acquisition of strain, load, temperature, humidity and other relevant data (e.g. from inertial sensors). The system contains a battery powered inductive energiser and demodulator to remotely power the implant electronics and demodulate the signals transmitted from the implanted device. Due to the housing of the internal coil, sufficient inductive coupling is obtained between the external and internal tuned circuits to enable simultaneous power and data transmission over the same inductive link. The actual performance of this system when used with one specific implant was studied, and some correspondence made to the relevant theory. Performance factors relating to both power efficiency and data reconstruction were identified. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

A Hands-on Guide to Video Podcasting

NASA Astrophysics Data System (ADS)

Christensen, L. L.; Hurt, R.

2008-02-01

Video podcasting, or vodcasting, is the latest evolution of the podcast revolution. The market for on demand multimedia content spans the gamut, ranging from portable media players to computers, and increasingly to televisions through home media centres. This new mode of accessing content is rapidly growing in popularity, particularly among younger audiences. Vodcasting allows a direct link between consumer and content producer, bypassing traditional media networks, making it ideal for EPO efforts. Even modest budgets can yield compelling astronomy vodcasts that will appeal to a large audience. Gateways like the iTunes Store and video community websites such as Veoh and YouTube have created new content markets where none existed before. This paper highlights the key steps for producing a vodcast and shows some statistics from two leading astronomy vodcasts. The reader will see how to make (or improve) a science video podcast and learn about some of the latest developments in this rapidly-evolving field.

Effectively incorporating selected multimedia content into medical publications.

PubMed

Ziegler, Alexander; Mietchen, Daniel; Faber, Cornelius; von Hausen, Wolfram; Schöbel, Christoph; Sellerer, Markus; Ziegler, Andreas

2011-02-17

Until fairly recently, medical publications have been handicapped by being restricted to non-electronic formats, effectively preventing the dissemination of complex audiovisual and three-dimensional data. However, authors and readers could significantly profit from advances in electronic publishing that permit the inclusion of multimedia content directly into an article. For the first time, the de facto gold standard for scientific publishing, the portable document format (PDF), is used here as a platform to embed a video and an audio sequence of patient data into a publication. Fully interactive three-dimensional models of a face and a schematic representation of a human brain are also part of this publication. We discuss the potential of this approach and its impact on the communication of scientific medical data, particularly with regard to electronic and open access publications. Finally, we emphasise how medical teaching can benefit from this new tool and comment on the future of medical publishing.

Hg diffusion in books of XVIII and XIX centuries by synchrotron microprobe

NASA Astrophysics Data System (ADS)

Pessanha, S.; Carvalho, M. L.; Manso, M.; Guilherme, A.; Marques, A. F.; Perez, C. A.

2009-08-01

The pigment vermilion (HgS) was used to color the fore edge, tail and head of books. Dissemination and quantification of Hg present in the ink used to color books from XVIII and XIX centuries are reported. Mercury is a very toxic element for the human body, therefore it is extremely important to know whether Hg tends to disseminate throughout the paper or stays confined to the borders of the books with less danger for readers. Synchrotron X-ray microprobe was used to evaluate Hg dissemination from the border to the centre of the paper sheet. The diffusion pattern of Hg was compared with the results obtained by a portable X-ray fluorescence spectrometer and mean quantitative calculations were obtained by a stationary X-ray fluorescence system with triaxial geometry. The results showed high concentrations of Hg in the external regions, but no diffusion was observed for the inner parts of the paper.

Research on imaging, sensing, and characterization of cells at Research Center for Applied Sciences (RCAS), Academia Sinica

NASA Astrophysics Data System (ADS)

Tsai, Hui-Chen; Chang, Chun-Fang; Chen, Bi-Chang; Cheng, Ji-Yen; Chu, Chih-Wei; Han, Hsieh-Cheng; Hatanaka, Koji; Hsieh, Tung-Han; Lee, Chau-Hwang; Lin, Jung-Hsin; Tung, Yi-Chung; Wei, Pei-Kuen; Yang, Fu-Liang; Tsai, Din Ping

2015-12-01

Development of imaging, sensing, and characterization of cells at Research Center for Applied Sciences (RCAS) of Academia Sinica in Taiwan is progressing rapidly. The research on advanced lattice light sheet microscopy for temporal visualization of cells in three dimensions at sub-cellular resolution shows novel imaging results. Label-free observation on filopodial dynamics provides a convenient assay on cancer cell motility. The newly-developed software enables us to track the movement of two types of particles through different channels and reconstruct the co-localized tracks. Surface plasmon resonance (SPR) for detecting urinary microRNA for diagnosis of acute kidney injury demonstrates excellent sensitivity. A fully automated and integrated portable reader was constructed as a home-based surveillance system for post-operation hepatocellular carcinoma. New microfluidic cell culture devices for fast and accurate characterizations prove various diagnosis capabilities.

Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in vivo studies.

PubMed

Petibon, Yoann; Rakvongthai, Yothin; El Fakhri, Georges; Ouyang, Jinsong

2017-05-07

Dynamic PET myocardial perfusion imaging (MPI) used in conjunction with tracer kinetic modeling enables the quantification of absolute myocardial blood flow (MBF). However, MBF maps computed using the traditional indirect method (i.e. post-reconstruction voxel-wise fitting of kinetic model to PET time-activity-curves-TACs) suffer from poor signal-to-noise ratio (SNR). Direct reconstruction of kinetic parameters from raw PET projection data has been shown to offer parametric images with higher SNR compared to the indirect method. The aim of this study was to extend and evaluate the performance of a direct parametric reconstruction method using in vivo dynamic PET MPI data for the purpose of quantifying MBF. Dynamic PET MPI studies were performed on two healthy pigs using a Siemens Biograph mMR scanner. List-mode PET data for each animal were acquired following a bolus injection of ~7-8 mCi of 18 F-flurpiridaz, a myocardial perfusion agent. Fully-3D dynamic PET sinograms were obtained by sorting the coincidence events into 16 temporal frames covering ~5 min after radiotracer administration. Additionally, eight independent noise realizations of both scans-each containing 1/8th of the total number of events-were generated from the original list-mode data. Dynamic sinograms were then used to compute parametric maps using the conventional indirect method and the proposed direct method. For both methods, a one-tissue compartment model accounting for spillover from the left and right ventricle blood-pools was used to describe the kinetics of 18 F-flurpiridaz. An image-derived arterial input function obtained from a TAC taken in the left ventricle cavity was used for tracer kinetic analysis. For the indirect method, frame-by-frame images were estimated using two fully-3D reconstruction techniques: the standard ordered subset expectation maximization (OSEM) reconstruction algorithm on one side, and the one-step late maximum a posteriori (OSL-MAP) algorithm on the other side, which incorporates a quadratic penalty function. The parametric images were then calculated using voxel-wise weighted least-square fitting of the reconstructed myocardial PET TACs. For the direct method, parametric images were estimated directly from the dynamic PET sinograms using a maximum a posteriori (MAP) parametric reconstruction algorithm which optimizes an objective function comprised of the Poisson log-likelihood term, the kinetic model and a quadratic penalty function. Maximization of the objective function with respect to each set of parameters was achieved using a preconditioned conjugate gradient algorithm with a specifically developed pre-conditioner. The performance of the direct method was evaluated by comparing voxel- and segment-wise estimates of [Formula: see text], the tracer transport rate (ml · min -1 · ml -1 ), to those obtained using the indirect method applied to both OSEM and OSL-MAP dynamic reconstructions. The proposed direct reconstruction method produced [Formula: see text] maps with visibly lower noise than the indirect method based on OSEM and OSL-MAP reconstructions. At normal count levels, the direct method was shown to outperform the indirect method based on OSL-MAP in the sense that at matched level of bias, reduced regional noise levels were obtained. At lower count levels, the direct method produced [Formula: see text] estimates with significantly lower standard deviation across noise realizations than the indirect method based on OSL-MAP at matched bias level. In all cases, the direct method yielded lower noise and standard deviation than the indirect method based on OSEM. Overall, the proposed direct reconstruction offered a better bias-variance tradeoff than the indirect method applied to either OSEM and OSL-MAP. Direct parametric reconstruction as applied to in vivo dynamic PET MPI data is therefore a promising method for producing MBF maps with lower variance.

Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in-vivo studies

PubMed Central

Petibon, Yoann; Rakvongthai, Yothin; Fakhri, Georges El; Ouyang, Jinsong

2017-01-01

Dynamic PET myocardial perfusion imaging (MPI) used in conjunction with tracer kinetic modeling enables the quantification of absolute myocardial blood flow (MBF). However, MBF maps computed using the traditional indirect method (i.e. post-reconstruction voxel-wise fitting of kinetic model to PET time-activity-curves -TACs) suffer from poor signal-to-noise ratio (SNR). Direct reconstruction of kinetic parameters from raw PET projection data has been shown to offer parametric images with higher SNR compared to the indirect method. The aim of this study was to extend and evaluate the performance of a direct parametric reconstruction method using in-vivo dynamic PET MPI data for the purpose of quantifying MBF. Dynamic PET MPI studies were performed on two healthy pigs using a Siemens Biograph mMR scanner. List-mode PET data for each animal were acquired following a bolus injection of ~7-8 mCi of 18F-flurpiridaz, a myocardial perfusion agent. Fully-3D dynamic PET sinograms were obtained by sorting the coincidence events into 16 temporal frames covering ~5 min after radiotracer administration. Additionally, eight independent noise realizations of both scans - each containing 1/8th of the total number of events - were generated from the original list-mode data. Dynamic sinograms were then used to compute parametric maps using the conventional indirect method and the proposed direct method. For both methods, a one-tissue compartment model accounting for spillover from the left and right ventricle blood-pools was used to describe the kinetics of 18F-flurpiridaz. An image-derived arterial input function obtained from a TAC taken in the left ventricle cavity was used for tracer kinetic analysis. For the indirect method, frame-by-frame images were estimated using two fully-3D reconstruction techniques: the standard Ordered Subset Expectation Maximization (OSEM) reconstruction algorithm on one side, and the One-Step Late Maximum a Posteriori (OSL-MAP) algorithm on the other side, which incorporates a quadratic penalty function. The parametric images were then calculated using voxel-wise weighted least-square fitting of the reconstructed myocardial PET TACs. For the direct method, parametric images were estimated directly from the dynamic PET sinograms using a maximum a posteriori (MAP) parametric reconstruction algorithm which optimizes an objective function comprised of the Poisson log-likelihood term, the kinetic model and a quadratic penalty function. Maximization of the objective function with respect to each set of parameters was achieved using a preconditioned conjugate gradient algorithm with a specifically developed pre-conditioner. The performance of the direct method was evaluated by comparing voxel- and segment-wise estimates of K1, the tracer transport rate (mL.min−1.mL−1), to those obtained using the indirect method applied to both OSEM and OSL-MAP dynamic reconstructions. The proposed direct reconstruction method produced K1 maps with visibly lower noise than the indirect method based on OSEM and OSL-MAP reconstructions. At normal count levels, the direct method was shown to outperform the indirect method based on OSL-MAP in the sense that at matched level of bias, reduced regional noise levels were obtained. At lower count levels, the direct method produced K1 estimates with significantly lower standard deviation across noise realizations than the indirect method based on OSL-MAP at matched bias level. In all cases, the direct method yielded lower noise and standard deviation than the indirect method based on OSEM. Overall, the proposed direct reconstruction offered a better bias-variance tradeoff than the indirect method applied to either OSEM and OSL-MAP. Direct parametric reconstruction as applied to in-vivo dynamic PET MPI data is therefore a promising method for producing MBF maps with lower variance. PMID:28379843

Direct parametric reconstruction in dynamic PET myocardial perfusion imaging: in vivo studies

NASA Astrophysics Data System (ADS)

Petibon, Yoann; Rakvongthai, Yothin; El Fakhri, Georges; Ouyang, Jinsong

2017-05-01

Dynamic PET myocardial perfusion imaging (MPI) used in conjunction with tracer kinetic modeling enables the quantification of absolute myocardial blood flow (MBF). However, MBF maps computed using the traditional indirect method (i.e. post-reconstruction voxel-wise fitting of kinetic model to PET time-activity-curves-TACs) suffer from poor signal-to-noise ratio (SNR). Direct reconstruction of kinetic parameters from raw PET projection data has been shown to offer parametric images with higher SNR compared to the indirect method. The aim of this study was to extend and evaluate the performance of a direct parametric reconstruction method using in vivo dynamic PET MPI data for the purpose of quantifying MBF. Dynamic PET MPI studies were performed on two healthy pigs using a Siemens Biograph mMR scanner. List-mode PET data for each animal were acquired following a bolus injection of ~7-8 mCi of 18F-flurpiridaz, a myocardial perfusion agent. Fully-3D dynamic PET sinograms were obtained by sorting the coincidence events into 16 temporal frames covering ~5 min after radiotracer administration. Additionally, eight independent noise realizations of both scans—each containing 1/8th of the total number of events—were generated from the original list-mode data. Dynamic sinograms were then used to compute parametric maps using the conventional indirect method and the proposed direct method. For both methods, a one-tissue compartment model accounting for spillover from the left and right ventricle blood-pools was used to describe the kinetics of 18F-flurpiridaz. An image-derived arterial input function obtained from a TAC taken in the left ventricle cavity was used for tracer kinetic analysis. For the indirect method, frame-by-frame images were estimated using two fully-3D reconstruction techniques: the standard ordered subset expectation maximization (OSEM) reconstruction algorithm on one side, and the one-step late maximum a posteriori (OSL-MAP) algorithm on the other side, which incorporates a quadratic penalty function. The parametric images were then calculated using voxel-wise weighted least-square fitting of the reconstructed myocardial PET TACs. For the direct method, parametric images were estimated directly from the dynamic PET sinograms using a maximum a posteriori (MAP) parametric reconstruction algorithm which optimizes an objective function comprised of the Poisson log-likelihood term, the kinetic model and a quadratic penalty function. Maximization of the objective function with respect to each set of parameters was achieved using a preconditioned conjugate gradient algorithm with a specifically developed pre-conditioner. The performance of the direct method was evaluated by comparing voxel- and segment-wise estimates of {{K}1} , the tracer transport rate (ml · min-1 · ml-1), to those obtained using the indirect method applied to both OSEM and OSL-MAP dynamic reconstructions. The proposed direct reconstruction method produced {{K}1} maps with visibly lower noise than the indirect method based on OSEM and OSL-MAP reconstructions. At normal count levels, the direct method was shown to outperform the indirect method based on OSL-MAP in the sense that at matched level of bias, reduced regional noise levels were obtained. At lower count levels, the direct method produced {{K}1} estimates with significantly lower standard deviation across noise realizations than the indirect method based on OSL-MAP at matched bias level. In all cases, the direct method yielded lower noise and standard deviation than the indirect method based on OSEM. Overall, the proposed direct reconstruction offered a better bias-variance tradeoff than the indirect method applied to either OSEM and OSL-MAP. Direct parametric reconstruction as applied to in vivo dynamic PET MPI data is therefore a promising method for producing MBF maps with lower variance.

Evaluation of the Deki Reader™, an automated RDT reader and data management device, in a household survey setting in low malaria endemic southwestern Uganda.

PubMed

Oyet, Caesar; Roh, Michelle E; Kiwanuka, Gertrude N; Orikiriza, Patrick; Wade, Martina; Parikh, Sunil; Mwanga-Amumpaire, Juliet; Boum, Yap

2017-11-07

Early diagnosis of suspected malaria cases with a rapid diagnostic test (RDT) has been shown to be an effective malaria control tool used in many resource-constrained settings. However, poor quality control and quality assurance hinder the accurate reporting of malaria diagnoses. Recent use of a portable, battery operated RDT reader (Deki Reader™, Fio Corporation) has shown to have high agreement with visual inspection across diverse health centre settings, however evidence of its feasibility and usability during cross sectional surveys are limited. This study aimed to evaluate the performance of the Deki Reader™ in a cross-sectional survey of children from southwestern Uganda. A two-stage, stratified cluster sampling survey was conducted between July and October 2014 in three districts of southwestern Uganda, with varying malaria transmission intensities. A total of 566 children aged 6-59 months were included in the analysis. Blood samples were collected and tested for malaria using: the SD Bioline Malaria Ag Pf/Pan RDT and microscopy. Results were compared between visual inspection of the RDT and by the Deki Reader™. Diagnostic performance of both methods were compared to gold-standard microscopy. The sensitivity and specificity of the Deki Reader™ was 94.1% (95% CI 69.2-99.6%) and 95.6% (95% CI 93.4-97.1%), respectively. The overall percent agreement between the Deki Reader™ and visual RDT inspection was 98.9% (95% CI 93.2-99.8), with kappa statistic of 0.92 (95% CI 0.85-0.98). The findings from this study suggest that the Deki Reader™ is comparable to visual inspection and performs well in detecting microscopy-positive Plasmodium falciparum cases in a household survey setting. However, the reader's performance was highly dependent on ensuring adequate battery life and a work environment free of dirt particles.

A portable data-logging system for industrial hygiene personal chlorine monitoring.

PubMed

Langhorst, M L; Illes, S P

1986-02-01

The combination of suitable portable sensors or instruments with small microprocessor-based data-logger units has made it possible to obtain detailed monitoring data for many health and environmental applications. Following data acquisition in field use, the logged data may be transferred to a desk-top personal computer for complete flexibility in manipulation of data and formating of results. A system has been assembled from commercial components and demonstrated for chlorine personal monitoring applications. The system consists of personal chlorine sensors, a Metrosonics data-logger and reader unit, and an Apple II Plus personal computer. The computer software was developed to handle sensor calibration, data evaluation and reduction, report formating and long-term storage of raw data on a disk. This system makes it possible to generate time-concentration profiles, evaluate dose above a threshold, quantitate short-term excursions and summarize time-weighted average (TWA) results. Field data from plant trials demonstrated feasibility of use, ruggedness and reliability. No significant differences were found between the time-weighted average chlorine concentrations determined by the sensor/logger system and two other methods: the sulfamic acid bubbler reference method and the 3M Poroplastic diffusional dosimeter. The sensor/data-logger system, however, provided far more information than the other two methods in terms of peak excursions, TWAs and exposure doses. For industrial hygiene applications, the system allows better definition of employee exposures, particularly for chemicals with acute as well as chronic health effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Portable microfluidic and smartphone-based devices for monitoring of cardiovascular diseases at the point of care.

PubMed

Hu, Jie; Cui, Xingye; Gong, Yan; Xu, Xiayu; Gao, Bin; Wen, Ting; Lu, Tian Jian; Xu, Feng

2016-01-01

Cardiovascular diseases (CVDs) are the main causes of morbidity and mortality in the world where about 4 in every 5 CVD deaths happen in low- and middle-income countries (LMICs). Most CVDs are preventable and curable, which is largely dependent on timely and effective interventions, including diagnosis, prognosis and therapeutic monitoring. However, these interventions are high-cost in high income countries and are usually lacking in LMICs. Thanks to the rapid development of microfluidics and nanotechnology, lots of portable analytical devices are developed for detection of CVDs at the point-of-care (POC). In the meantime, smartphone, as a versatile and powerful handheld tool, has been employed not only as a reader for microfluidic assays, but also as an analyzer for physiological indexes. In this review, we present a comprehensive introduction of the current status and potential development direction on POC diagnostics for CVDs. First of all, we introduce some main facts about CVDs and their standard diagnostic procedures and methods. Second, we discuss about both commercially available POC devices and developed prototypes for detection of CVDs via immunoassays. Subsequently, we report the advances in smartphone-based readout for microfluidic assays. Finally, we present some examples using smartphone, individually or combined with other components or devices, for CVD monitoring. We envision an integrated smartphone-based system capable of functioning blood tests, disease examination, and imaging will come in the future. Copyright © 2016 Elsevier Inc. All rights reserved.

Analyzing Dental Implant Sites From Cone Beam Computed Tomography Scans on a Tablet Computer: A Comparative Study Between iPad and 3 Display Systems.

PubMed

Carrasco, Alejandro; Jalali, Elnaz; Dhingra, Ajay; Lurie, Alan; Yadav, Sumit; Tadinada, Aditya

2017-06-01

The aim of this study was to compare a medical-grade PACS (picture archiving and communication system) monitor, a consumer-grade monitor, a laptop computer, and a tablet computer for linear measurements of height and width for specific implant sites in the posterior maxilla and mandible, along with visualization of the associated anatomical structures. Cone beam computed tomography (CBCT) scans were evaluated. The images were reviewed using PACS-LCD monitor, consumer-grade LCD monitor using CB-Works software, a 13″ MacBook Pro, and an iPad 4 using OsiriX DICOM reader software. The operators had to identify anatomical structures in each display using a 2-point scale. User experience between PACS and iPad was also evaluated by means of a questionnaire. The measurements were very similar for each device. P-values were all greater than 0.05, indicating no significant difference between the monitors for each measurement. The intraoperator reliability was very high. The user experience was similar in each category with the most significant difference regarding the portability where the PACS display received the lowest score and the iPad received the highest score. The iPad with retina display was comparable with the medical-grade monitor, producing similar measurements and image visualization, and thus providing an inexpensive, portable, and reliable screen to analyze CBCT images in the operating room during the implant surgery.

Image stacking approach to increase sensitivity of fluorescence detection using a low cost complementary metal-oxide-semiconductor (CMOS) webcam.

PubMed

Balsam, Joshua; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

2012-01-01

Optical technologies are important for biological analysis. Current biomedical optical analyses rely on high-cost, high-sensitivity optical detectors such as photomultipliers, avalanched photodiodes or cooled CCD cameras. In contrast, Webcams, mobile phones and other popular consumer electronics use lower-sensitivity, lower-cost optical components such as photodiodes or CMOS sensors. In order for consumer electronics devices, such as webcams, to be useful for biomedical analysis, they must have increased sensitivity. We combined two strategies to increase the sensitivity of CMOS-based fluorescence detector. We captured hundreds of low sensitivity images using a Webcam in video mode, instead of a single image typically used in cooled CCD devices.We then used a computational approach consisting of an image stacking algorithm to remove the noise by combining all of the images into a single image. While video mode is widely used for dynamic scene imaging (e.g. movies or time-lapse photography), it is not used to capture a single static image, which removes noise and increases sensitivity by more than thirty fold. The portable, battery-operated Webcam-based fluorometer system developed here consists of five modules: (1) a low cost CMOS Webcam to monitor light emission, (2) a plate to perform assays, (3) filters and multi-wavelength LED illuminator for fluorophore excitation, (4) a portable computer to acquire and analyze images, and (5) image stacking software for image enhancement. The samples consisted of various concentrations of fluorescein, ranging from 30 μM to 1000 μM, in a 36-well miniature plate. In the single frame mode, the fluorometer's limit-of-detection (LOD) for fluorescein is ∼1000 μM, which is relatively insensitive. However, when used in video mode combined with image stacking enhancement, the LOD is dramatically reduced to 30 μM, sensitivity which is similar to that of state-of-the-art ELISA plate photomultiplier-based readers. Numerous medical diagnostics assays rely on optical and fluorescence readers. Our novel combination of detection technologies, which is new to biodetection may enable the development of new low cost optical detectors based on an inexpensive Webcam (<$10). It has the potential to form the basis for high sensitivity, low cost medical diagnostics in resource-poor settings.

Image stacking approach to increase sensitivity of fluorescence detection using a low cost complementary metal-oxide-semiconductor (CMOS) webcam

PubMed Central

Balsam, Joshua; Bruck, Hugh Alan; Kostov, Yordan; Rasooly, Avraham

2013-01-01

Optical technologies are important for biological analysis. Current biomedical optical analyses rely on high-cost, high-sensitivity optical detectors such as photomultipliers, avalanched photodiodes or cooled CCD cameras. In contrast, Webcams, mobile phones and other popular consumer electronics use lower-sensitivity, lower-cost optical components such as photodiodes or CMOS sensors. In order for consumer electronics devices, such as webcams, to be useful for biomedical analysis, they must have increased sensitivity. We combined two strategies to increase the sensitivity of CMOS-based fluorescence detector. We captured hundreds of low sensitivity images using a Webcam in video mode, instead of a single image typically used in cooled CCD devices.We then used a computational approach consisting of an image stacking algorithm to remove the noise by combining all of the images into a single image. While video mode is widely used for dynamic scene imaging (e.g. movies or time-lapse photography), it is not used to capture a single static image, which removes noise and increases sensitivity by more than thirty fold. The portable, battery-operated Webcam-based fluorometer system developed here consists of five modules: (1) a low cost CMOS Webcam to monitor light emission, (2) a plate to perform assays, (3) filters and multi-wavelength LED illuminator for fluorophore excitation, (4) a portable computer to acquire and analyze images, and (5) image stacking software for image enhancement. The samples consisted of various concentrations of fluorescein, ranging from 30 μM to 1000 μM, in a 36-well miniature plate. In the single frame mode, the fluorometer's limit-of-detection (LOD) for fluorescein is ∼1000 μM, which is relatively insensitive. However, when used in video mode combined with image stacking enhancement, the LOD is dramatically reduced to 30 μM, sensitivity which is similar to that of state-of-the-art ELISA plate photomultiplier-based readers. Numerous medical diagnostics assays rely on optical and fluorescence readers. Our novel combination of detection technologies, which is new to biodetection may enable the development of new low cost optical detectors based on an inexpensive Webcam (<$10). It has the potential to form the basis for high sensitivity, low cost medical diagnostics in resource-poor settings. PMID:23990697

HAZPAC; an interactive map of Pacific Rim natural hazards, population, and infrastructure

USGS Publications Warehouse

Bemis, B.L.; Goss, H.V.; Yurkovich, E.S.; Perron, T.J.; Howell, D.G.

2002-01-01

This is an online version of a CD-ROM publication. The text files that describe using this publication make reference to software provided on the disc. For this online version the software can be downloaded for free from Adobe Systems and Environmental Systems Research Institute, Inc. (ESRI). Welcome to HAZPAC! HAZPAC is an interactive map about natural hazard risk in the Pacific Rim region. It is intended to communicate to a broad audience the ideas of 'Crowding the Rim,' which is an international, public-private partnership that fosters collaborative solutions for regional risks. HAZPAC, which stands for 'HAZards of the PACific,' uses Geographic Information System (GIS) technology to help people visualize the socioeconomic connections and shared hazard vulnerabilities among Pacific Rim countries, as well as to explore the general nature of risk. Please refer to the 'INTRODUCTION TO HAZPAC' section of the readme file below to determine which HAZPAC project will be right for you. Once you have decided which HAZPAC project is suitable for you, please refer to the 'GETTING STARTED' sections in the readme file for some basic information that will help you begin using HAZPAC. Also, we highly recommend that you follow the Tutorial exercises in the project-specific HAZPAC User Guides. The User Guides are PDF (Portable Document Format) files that must be read with Adobe Acrobat Reader (a free copy of Acrobat Reader is available using the link near the bottom of this page).

Principles for new optical techniques in medical diagnostics for mHealth applications

NASA Astrophysics Data System (ADS)

Balsam, Joshua Michael

Medical diagnostics is a critical element of effective medical treatment. However, many modern and emerging diagnostic technologies are not affordable or compatible with the needs and conditions found in low-income and middle-income countries and regions. Resource-poor areas require low-cost, robust, easy-to-use, and portable diagnostics devices compatible with telemedicine (i.e. mHealth) that can be adapted to meet diverse medical needs. Many suitable devices will need to be based on optical technologies, which are used for many types of biological analyses. This dissertation describes the fabrication and detection principles for several low-cost optical technologies for mHealth applications including: (1) a webcam based multi-wavelength fluorescence plate reader, (2) a lens-free optical detector used for the detection of Botulinum A neurotoxin activity, (3) a low cost micro-array reader that allows the performance of typical fluorescence based assays demonstrated for the detection of the toxin staphylococcal enterotoxin (SEB), and (4) a wide-field flow cytometer for high throughput detection of fluorescently labeled rare cells. This dissertation discusses how these technologies can be harnessed using readily available consumer electronics components such as webcams, cell phones, CCD cameras, LEDs, and laser diodes. There are challenges in developing devices with sufficient sensitivity and specificity, and approaches are presented to overcoming these challenges to create optical detectors that can serve as low cost medical diagnostics in resource-poor settings for mHealth.

Fine Sediment Residency in Streambeds in Southeastern Australia.

NASA Astrophysics Data System (ADS)

Croke, J. C.; Thompson, C. J.; Rhodes, E.

2007-12-01

A detailed understanding of channel forming and maintenance processes in streams requires some measurement and/or prediction of bed load transport and sediment mobility. Traditional field based measurements of such processes are often problematic due to the high discharge characteristics of upland streams. In part to compensate for such difficulties, empirical flow competence equations have also been developed to predict armour or bedform stabilising grain mobility. These equations have been applied to individual reaches to predict the entrainment of a threshold grain size and the vertical extent of flushing. In cobble- and boulder-bed channels the threshold grain size relates to the size of the bedform stabilising grains (eg. D84, D90). This then allows some prediction of when transport of the matrix material occurs. The application of Optically Stimulated Luminescence (OSL) dating is considered here as an alternative and innovative way to determine fine sediment residency times in stream beds. Age estimates derived from the technique are used to assist in calibrating sediment entrainment models to specific channel types and hydrological regimes. The results from a one-dimensional HEC-RAS model indicate that recurrence interval floods exceeding bankfull up to 13 years are competent to mobilise the maximum overlying surface grain sizes at the sites. OSL minimum age model results of well bleached quartz in the fine matrix particles are in general agreement with selected competence equation predictions. The apparent long (100-1400y) burial age of most of the mineral quartz suggests that competent flows are not able to flush all subsurface fine-bed material. Maximum bed load exchange (flushing) depth was limited to twice the depth of the overlying D90 grain size. Application of OSL in this study provides important insight into the nature of matrix material storage and flushing in mountain streams.

Towards an Accurate and Precise Chronology for the Colonization of Australia: The Example of Riwi, Kimberley, Western Australia.

PubMed

Wood, Rachel; Jacobs, Zenobia; Vannieuwenhuyse, Dorcas; Balme, Jane; O'Connor, Sue; Whitau, Rose

An extensive series of 44 radiocarbon (14C) and 37 optically stimulated luminescence (OSL) ages have been obtained from the site of Riwi, south central Kimberley (NW Australia). As one of the earliest known Pleistocene sites in Australia, with archaeologically sterile sediment beneath deposits containing occupation, the chronology of the site is important in renewed debates surrounding the colonization of Sahul. Charcoal is preserved throughout the sequence and within multiple discrete hearth features. Prior to 14C dating, charcoal has been pretreated with both acid-base-acid (ABA) and acid base oxidation-stepped combustion (ABOx-SC) methods at multiple laboratories. Ages are consistent between laboratories and also between the two pretreatment methods, suggesting that contamination is easily removed from charcoal at Riwi and the Pleistocene ages are likely to be accurate. Whilst some charcoal samples recovered from outside hearth features are identified as outliers within a Bayesian model, all ages on charcoal within hearth features are consistent with stratigraphy. OSL dating has been undertaken using single quartz grains from the sandy matrix. The majority of samples show De distributions that are well-bleached but that also include evidence for mixing as a result of post-depositional bioturbation of the sediment. The results of the two techniques are compared and evaluated within a Bayesian model. Consistency between the two methods is good, and we demonstrate human occupation at this site from 46.4-44.6 cal kBP (95.4% probability range). Importantly, the lowest archaeological horizon at Riwi is underlain by sterile sediments which have been dated by OSL making it possible to demonstrate the absence of human occupation for between 0.9-5.2 ka (68.2% probability range) prior to occupation.

Towards an Accurate and Precise Chronology for the Colonization of Australia: The Example of Riwi, Kimberley, Western Australia

PubMed Central

Balme, Jane; O’Connor, Sue; Whitau, Rose

2016-01-01

An extensive series of 44 radiocarbon (14C) and 37 optically stimulated luminescence (OSL) ages have been obtained from the site of Riwi, south central Kimberley (NW Australia). As one of the earliest known Pleistocene sites in Australia, with archaeologically sterile sediment beneath deposits containing occupation, the chronology of the site is important in renewed debates surrounding the colonization of Sahul. Charcoal is preserved throughout the sequence and within multiple discrete hearth features. Prior to 14C dating, charcoal has been pretreated with both acid-base-acid (ABA) and acid base oxidation-stepped combustion (ABOx-SC) methods at multiple laboratories. Ages are consistent between laboratories and also between the two pretreatment methods, suggesting that contamination is easily removed from charcoal at Riwi and the Pleistocene ages are likely to be accurate. Whilst some charcoal samples recovered from outside hearth features are identified as outliers within a Bayesian model, all ages on charcoal within hearth features are consistent with stratigraphy. OSL dating has been undertaken using single quartz grains from the sandy matrix. The majority of samples show De distributions that are well-bleached but that also include evidence for mixing as a result of post-depositional bioturbation of the sediment. The results of the two techniques are compared and evaluated within a Bayesian model. Consistency between the two methods is good, and we demonstrate human occupation at this site from 46.4–44.6 cal kBP (95.4% probability range). Importantly, the lowest archaeological horizon at Riwi is underlain by sterile sediments which have been dated by OSL making it possible to demonstrate the absence of human occupation for between 0.9–5.2 ka (68.2% probability range) prior to occupation. PMID:27655174

Response of Nanodot Optically Stimulated Luminescence Dosimeters to Therapeutic Electron Beams.

PubMed

Ponmalar, Y Retna; Manickam, Ravikumar; Sathiyan, S; Ganesh, K M; Arun, R; Godson, Henry Finlay

2017-01-01

Response of Al 2 O 3 :C-based nanoDot optically stimulated luminescence (OSL) dosimeter was studied for the dosimetry of 6, 9, 12, 16, and 20 MeV therapeutic electron beams. With reference to ionization chamber, no change in the response was observed with the change in the energy of electron beams for the field size from 6 cm × 6 cm to 25 cm × 25 cm, dose rates from 100 MU/min to 600 MU/min, and the linearity in the response up to 300 cGy. The fading of the transient signal was higher for 20 MeV electron beam than that of 6 MeV electron beam by about 5% as compared to value at 20 min after irradiation. The depletion of OSL signal per readout in 200 successive readouts was also found to change with dose and energy of electron beam from 6 MeV (9% and 12% per readout at 2 and 10 Gy, respectively) to 20 MeV (9% and 16% at 2 and 10 Gy, respectively). The OSL sensitivity changed in the range from 2% to 6% with accumulated doses from 2 to 8 Gy and with electron energy from 6 to 20 MeV, but the sensitivity could be reset using an optical annealing treatment. Although negligible fading for postirradiation storage from 20 min to several months, acceptable precision and linearity in the desired range, and high reproducibility makes nanoDot dosimeters very attractive for the dosimetry of therapeutic electron beams, a note should be made for changes in sensitivity at doses beyond 2 Gy and electron beams energy dependence in reuse, short-term fading, and signal depletion on repeated readout.

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children

PubMed Central

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Objectives: Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot® (Landauer, Glenwood, IL, USA). Background: Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. Materials and Methods: The nanoDot® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. Results: A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3–86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values (R2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Conclusions: Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients. PMID:29440825

Response of Nanodot Optically Stimulated Luminescence Dosimeters to Therapeutic Electron Beams

PubMed Central

Ponmalar, Y. Retna; Manickam, Ravikumar; Sathiyan, S.; Ganesh, K. M.; Arun, R.; Godson, Henry Finlay

2017-01-01

Response of Al2O3:C-based nanoDot optically stimulated luminescence (OSL) dosimeter was studied for the dosimetry of 6, 9, 12, 16, and 20 MeV therapeutic electron beams. With reference to ionization chamber, no change in the response was observed with the change in the energy of electron beams for the field size from 6 cm × 6 cm to 25 cm × 25 cm, dose rates from 100 MU/min to 600 MU/min, and the linearity in the response up to 300 cGy. The fading of the transient signal was higher for 20 MeV electron beam than that of 6 MeV electron beam by about 5% as compared to value at 20 min after irradiation. The depletion of OSL signal per readout in 200 successive readouts was also found to change with dose and energy of electron beam from 6 MeV (9% and 12% per readout at 2 and 10 Gy, respectively) to 20 MeV (9% and 16% at 2 and 10 Gy, respectively). The OSL sensitivity changed in the range from 2% to 6% with accumulated doses from 2 to 8 Gy and with electron energy from 6 to 20 MeV, but the sensitivity could be reset using an optical annealing treatment. Although negligible fading for postirradiation storage from 20 min to several months, acceptable precision and linearity in the desired range, and high reproducibility makes nanoDot dosimeters very attractive for the dosimetry of therapeutic electron beams, a note should be made for changes in sensitivity at doses beyond 2 Gy and electron beams energy dependence in reuse, short-term fading, and signal depletion on repeated readout. PMID:28405107

Fiber-coupled Luminescence Dosimetry in Therapeutic and Diagnostic Radiology

NASA Astrophysics Data System (ADS)

Andersen, Claus E.

2011-05-01

Fiber-coupled luminescence dosimetry is an emerging technology with several potentially attractive features of relevance for uses in therapeutic and diagnostic radiology: direct water equivalence (i.e. no significant perturbation of the radiation field in a water phantom or a patient), sub-mm detector size, high dynamic range (below a mGy to several Gy), microsecond time resolution, and absence of electrical wires or other electronics in the dosimeter probe head. Fiber-coupled luminescence dosimetry systems typically consist of one or more small samples of phosphor, e.g. a mg of plastic scintillator, attached to 10-20 m long optical fiber cables of plastic. During irradiation, each dosimeter probe spontaneously emits radioluminescence (RL) in proportion to the dose rate. The luminescence intensity can be detected with photomultiplier tubes, CCD cameras or other highly sensitive photodetectors. Some crystalline phosphors, such as carbon-doped aluminium oxide (Al2O3:C) have the ability to store charge produced in the crystal during irradiation. The stored charge may later be released by fiber-guided laser light under emission of so-called optically stimulated luminescence (OSL). The OSL signal therefore reflects the passively integrated dose. In contrast to thermoluminescence dosimetry, fiber-coupled OSL dosimetry may be performed in vivo while the dosimeter is still in the patient. Within the last few years, several improvements and new applications of these techniques have been published, and the objective of this review is to provide an introduction to this field and to outline some of these new results. Emphasis will be given to applications in medical dosimetry such as in vivo real-time dose verification in brachytherapy and methods aimed for improved quality assurance of linear accelerators.

SU-E-J-11: Measurement of Eye Lens Dose for Varian On-Board Imaging with Different CBCT Acquisition Techniques

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deshpande, S; Dhote, D; Kumar, R

Purpose: To measure actual patient eye lens dose for different cone beam computed tomography (CBCT) acquisition protocol of Varian’s On Board Imagining (OBI) system using Optically Stimulated Luminescence (OSL) dosimeter and study the eye lens dose with patient geometry and distance of isocenter to the eye lens Methods: OSL dosimeter was used to measure eye lens dose of patient. OSL dosimeter was placed on patient forehead center during CBCT image acquisition to measure eye lens dose. For three different cone beam acquisition protocol (standard dose head, low dose head and high quality head) of Varian On-Board Imaging, eye lens dosesmore » were measured. Measured doses were correlated with patient geometry and distance between isocenter to eye lens. Results: Measured eye lens dose for standard dose head was in the range of 1.8 mGy to 3.2 mGy, for high quality head protocol dose was in range of 4.5mGy to 9.9 mGy whereas for low dose head was in the range of 0.3mGy to 0.7mGy. Dose to eye lens is depends upon position of isocenter. For posterioraly located tumor eye lens dose is less. Conclusion: From measured doses it can be concluded that by proper selection of imagining protocol and frequency of imaging, it is possible to restrict the eye lens dose below the new limit set by ICRP. However, undoubted advantages of imaging system should be counter balanced by careful consideration of imaging protocol especially for very intense imaging sequences for Adoptive Radiotherapy or IMRT.« less

The current status of eye lens dose measurement in interventional cardiology personnel in Thailand.

PubMed

Krisanachinda, Anchali; Srimahachota, Suphot; Matsubara, Kosuke

2017-06-01

Workers involved in interventional cardiology procedures receive high eye lens doses if radiation protection tools are not properly utilized. Currently, there is no suitable method for routine measurement of eye dose. In Thailand, the eye lens equivalent doses in terms of Hp(3) of the interventional cardiologists, nurses, and radiographers participating in interventional cardiology procedures have been measured at 12 centers since 2015 in the pilot study. The optically stimulated luminescence (OSL) dosimeter was used for measurement of the occupational exposure and the eye lens dose of 42 interventional cardiology personnel at King Chulalongkorn Memorial Hospital as one of the pilot centers. For all personnel, it is recommended that a first In Light OSL badge is placed at waist level and under the lead apron for determination of Hp(10); a second badge is placed at the collar for determination of Hp(0.07) and estimation of Hp(3). Nano Dots OSL dosimeter has been used as an eye lens dosimeter for 16 interventional cardiology personnel, both with and without lead-glass eyewear. The mean effective dose at the body, equivalent dose at the collar, and estimated eye lens dose were 0.801, 5.88, and 5.70 mSv per year, respectively. The mean eye lens dose measured by the Nano Dots dosimeter was 8.059 mSv per year on the left eye and 3.552 mSv per year on the right eye. Two of 16 interventional cardiologists received annual eye lens doses on the left side without lead glass that were higher than 20 mSv per year, the new eye lens dose limit as recommended by ICRP with the risk of eye lens opacity and cataract.

Comparison of skin dose measurement using nanoDot® dosimeter and machine readings of radiation dose during cardiac catheterization in children.

PubMed

Balaguru, Duraisamy; Rodriguez, Matthew; Leon, Stephanie; Wagner, Louis K; Beasley, Charles W; Sultzer, Andrew; Numan, Mohammed T

2018-01-01

Direct measurement of skin dose of radiation for children using optically stimulated luminescence (OSL) technology using nanoDot ® (Landauer, Glenwood, IL, USA). Radiation dose is estimated as cumulative air kerma (AK) and dosearea product based on standards established for adult size patients. Body size of pediatric patients who undergo cardiac catheterization for congenital heart disease vary widely from newborn to adolescence. Direct, skindose measurement applying OSL technology may eliminate errors in the estimate. The nanoDot ® (1 cm × 1 cm × flat plastic cassette) is applied to patient's skin using adhesive tape during cardiac catheterization and radiation skin doses were read within 24 hrs. nanoDot ® values were compared to the currently available cumulative AK values estimated and displayed on fluoroscopy monitor. A total of 12 children were studied, aged 4 months to 18 years (median 1.1 years) and weight range 5.3-86 kg (median 8.4 kg). nanoDot® readings ranged from 2.58 mGy to 424.8 mGy (median 84.1 mGy). Cumulative AK ranged from 16.2 mGy to 571.2 mGy (median 171.1 mGy). Linear correlation was noted between nanoDot® values and AK values ( R 2 = 0.88, R = 0.94). nanoDot® readings were approximately 65% of the estimated cumulative AK estimated using the International Electrotechnical Commission standards. Application of OSL technology using nanoDot® provides an alternative to directly measure fluoroscopic skin dose in children during cardiac catheterization. Our data show that the actual skin dose for children is approximately one-third lower than the AK estimated using international standards for adult size patients.

Using OSL to decipher past soil history in archaeological terraces, Judea Highlands, Israel

NASA Astrophysics Data System (ADS)

Porat, Naomi; Gadot, Yuval; Davidovich, Uri; Avni, Yoav; Avni, Gideon; Golan, Dani

2015-04-01

Archaeological terraces are the most prominent feature of the agricultural sphere in the hilly landscape throughout the Mediterranean. Using terrace walls for the artificial creation of arable plots of land was a major technological innovation that has completely altered the natural terrain. As such, the dating of these simply built features is of upmost importance. Archaeological excavations and OSL dating of the soil infill of terraces were carried out in three excavation areas at Mt. Eitan in the Judea Highlands, Israel. Previous survey showed that Mt. Eitan was settled continuously at least from the Middle Bronze Age (ca 3800 years ago) and until modern times. The OSL ages shows that all extant terraces were constructed in the past 550-200 years, in the Ottoman period. Older ages are limited only to the base of a few terraces, and they range from the Roman Period (ca 1800 years ago) to Mamluk times (ca 700 years ago). Many of the soil samples contain quartz grains with older ages, indicating incomplete bleaching of the sediment at the time of terrace construction. We used the finite mixture model to find out if there are distinct age clusters to these poorly bleached grains. Analyses were carried out on a compilation of all measured De values (small aliquots) from the entire study area, and for each area separately. Results show that the unbleached grains cluster into only a few periods and highlight four synchronous episodes of terrace building in the past 800 years. The Roman and Early Islamic periods are also represented, even in area where soils with such ages were not found. The unbleached grains preserve older episodes of terrace building no longer represented in the landscape.

Dating of river terraces along Lefthand Creek, western High Plains, Colorado, reveals punctuated incision

NASA Astrophysics Data System (ADS)

Foster, Melissa A.; Anderson, Robert S.; Gray, Harrison J.; Mahan, Shannon A.

2017-10-01

The response of erosional landscapes to Quaternary climate oscillations is recorded in fluvial terraces whose quantitative interpretation requires numerical ages. We investigate gravel-capped strath terraces along the western edge of Colorado's High Plains to constrain the incision history of this shale-dominated landscape. We use 10Be and 26Al cosmogenic radionuclides (CRNs), optically stimulated luminescence (OSL), and thermally transferred OSL (TT-OSL) to date three strath terraces, all beveled in shale bedrock and then deposited upon by Lefthand Creek, which drains the crystalline core of the Front Range. Our study reveals: (i) a long history (hundreds of thousands of years) of fluvial occupation of the second highest terrace, T2 (Table Mountain), with fluvial abandonment at 92 ± 3 ka; (ii) a brief occupation of a narrow and spatially confined terrace, T3, at 98 ± 7 ka; and (iii) a 10-25 thousand year period of cutting and fluvial occupation of a lower terrace, T4, marked by the deposition of a lower alluvial unit between 59 and 68 ka, followed by deposition of an upper alluvial package at 40 ± 3 ka. In conjunction with other recent CRN studies of strath terraces along the Colorado Front Range (Riihimaki et al., 2006; Dühnforth et al., 2012), our data reveal that long periods of lateral planation and fluvial occupation of strath terraces, sometimes lasting several glacial-interglacial cycles, are punctuated by brief episodes of rapid vertical bedrock incision. These data call into question what a singular terrace age represents, as the strath may be cut at one time (its cutting-age) and the terrace surface may be abandoned at a much later time (its abandonment age), and challenge models of strath terraces that appeal to simple pacing by the glacial-interglacial cycles.

Potential application of metal nanoparticles for dosimetric systems: Concepts and perspectives

NASA Astrophysics Data System (ADS)

Guidelli, Eder José; Baffa, Oswaldo

2014-11-01

Metallic nanoparticles increase the delivered dose and consequently enhance tissue radio sensitization during radiation therapy of cancer. The Dose Enhancement Factor (DEF) corresponds to the ratio between the dose deposited on a tissue containing nanoparticles, and the dose deposited on a tissue without nanoparticles. In this sense, we have used electron spin resonance spectroscopy (ESR) to investigate how silver and gold nanoparticles affect the dose deposition in alanine dosimeters, which act as a surrogate of soft tissue. Besides optimizing radiation absorption by the dosimeter, the optical properties of these metal nanoparticles could also improve light emission from materials employed as radiation detectors. Therefore, we have also examined how the plasmonic properties of noble metal nanoparticles could enhance radiation detection using optically stimulated luminescence (OSL) dosimetry. This work will show results on how the use of gold and silver nanoparticles are beneficial for the ESR and OSL dosimetric techniques, and will describe the difficulties we have been facing, the challenges to overcome, and the perspectives.

Evaluation of radiation exposure with Tru-Align intraoral rectangular collimation system using OSL dosimeters.

PubMed

Goren, Arthur D; Bonvento, Michael J; Fernandez, Thomas J; Abramovitch, Kenneth; Zhang, Wenjian; Roe, Nadine; Seltzer, Jared; Steinberg, Mitchell; Colosi, Dan C

2011-03-01

A pilot study to compare radiation exposure with the Tru-Align rectangular collimation system to round collimation exposures was undertaken. Radiation exposure at various points within the cross sections of the collimators and entrance, intraoral and exit dose measurements were measured using InLight OSL dosimeters. Overall dose reduction with the use of the rectangular collimation system was estimated by taking into account the ratios of collimator openings and the average radiation exposure at the measurement points. Use of the Tru-Align system resulted in an average radiation exposure within the perimeter of the projected outline of the rectangular collimator of 36.1 mR, compared to 148.5 mR with the round collimator. Our calculations indicate a dose reduction by a factor of approximately 3.2 in the case of the Tru-Align system compared to round collimation. The Tru-Align system was easy to use, but in some situations failed to allow Xray coverage of the entire surface of the image receptor, leading to cone cuts.

Photoluminescence, optically stimulated luminescence, and thermoluminescence study of RbMgF3:Eu2+

NASA Astrophysics Data System (ADS)

Dotzler, C.; Williams, G. V. M.; Rieser, U.; Robinson, J.

2009-01-01

Optically stimulated luminescence (OSL) and thermoluminescence are observed in polycrystalline RbMgF3:Eu2+ after x-ray, γ-ray, or β irradiation. The main electron traps are F-centers but there are other unidentified traps. The main hole traps at room temperature are probably Eu3+ and thermal or optical stimulation leads to electron-hole recombination at the Eu3+ site and Eu2+ emissions arising from P6J to S87/2 and 4f5d(Eg) to S87/2 transitions. We find that some of the electron traps can be emptied by infrared stimulation and all of the electron traps can be emptied by white light stimulation. The OSL dark decay is long and exceeds 5 days for traps that are emptied by white light stimulation after initial infrared bleaching. Our results show that this compound can be used as a radiation dosimeter for intermediate dose levels where the R87b self-dose does not significantly affect the dose reading.

TL and OSL dose response of LiF:Mg,Ti and Al2O3:C dosimeters using a PMMA phantom for IMRT technique quality assurance.

PubMed

Matsushima, Luciana C; Veneziani, Glauco R; Sakuraba, Roberto K; Cruz, José C; Campos, Letícia L

2015-06-01

The principle of IMRT is to treat a patient from a number of different directions (or continuous arcs) with beams of nonuniform fluences, which have been optimized to deliver a high dose to the target volume and an acceptably low dose to the surrounding normal structures (Khan, 2010). This study intends to provide information to the physicist regarding the application of different dosimeters type, phantoms and analysis technique for Intensity Modulated Radiation Therapy (IMRT) dose distributions evaluation. The measures were performed using dosimeters of LiF:Mg,Ti and Al2O3:C evaluated by techniques of thermoluminescent (TL) and Optically Stimulated Luminescence (OSL). A polymethylmethacrylate (PMMA) phantom with five cavities, two principal target volumes considered like tumours to be treated and other three cavities to measure the scattered radiation dose was developed to carried out the measures. Copyright © 2015 Elsevier Ltd. All rights reserved.

East Europe Report, Scientific Affairs, Number 749

DTIC Science & Technology

1982-07-23

Scientific Associate A. Andreev, Corresponding Member D. Shopov , Scientific Associate B. Kunev, V. Idakiev and A. Bankova. A collective at the Economic...operational systems — manual, automatic and remote control; control system — G P oSL ?nP™ y measurement ~ automatic and in percentage figures; power

New Quaternary geochronometric constraints on river incision in the Virginia Piedmont: Relative contributions of climate, base-level fall, knickpoint retreat, and active tectonics

NASA Astrophysics Data System (ADS)

Malenda, Helen Fitzgerald

River terraces are fluvial landforms that represent flood plains abandoned through river incision and, when accurately correlated and dated, can serve as paleogeodetic markers, indicating the elevation and location of past channels and the subsequent fluvial and tectonic processes shaping the landscape. Fluvial terraces are most useful when the incision processes that caused their abandonment and formation are better understood. This thesis studies river incision reconstructed from fluvial terraces of the South Anna River in the central Virginia Piedmont, USA. The South Anna River flows directly above an active fault, on which large, but infrequent seismic events have occurred, and the most recent event was the 23 August 2011 Mineral earthquake. Two conceptual incision models are tested to better understand the fluvial response to active tectonics in this region: 1) spatially-uniform vertical incision and 2) diachronous horizontal knickpoint retreat. Here, terraces and incision were evaluated in the context of a 1:24,000 scale surficial map of alluvial deposits, optically stimulated luminescence (OSL) and infrared luminescence (IRSL) geochronology, and knickpoint celerity modeling. The South Anna River and its tributaries traverse across the geologic, topographic and structural grain of central Virginia Piedmont, USA, a region known for Late Cenozoic base-level fall, high amplitude climate changes, and historic seismicity. Litho- and pedostratigraphically correlative deposits are found to form five groups of terraces (Qt1-Qt5) with similar, but not exact relative elevations above modern channel. Within these groups, the terraces have similar OSL/IRSL ages that do not systematically decrease in age upstream towards knickpoint in the modern channel. Similarly, the modeled rate of knickpoint retreat through the South Anna channel of ~7-14km/Ma is too slow to explain the time-transgressive OSL/IRSL dates for any terrace group. Terrace formation by knickpoint migration and horizontal floodplain abandonment is rejected as a dominant process in terrace formation, in favor of more spatially-uniform vertical incision. In this landscape, the OSL/IRSL results suggest that flood plains are widened and then are abandoned and become terraces as the South Anna channel responds to climatically-driven unsteady changes in discharge and sediment yield. The complex age-elevation relationships of terraces proximal to epicenter of the 23 August 2011 Mineral earthquake argue for a terrace correlation that allows for rock uplift consistent with the co-seismic response of the 2011 Mineral earthquake.

Ages, durations and behavioural implications of Middle Stone Age industries in southern Africa: advances in optical dating of individual grains of quartz

NASA Astrophysics Data System (ADS)

Jacobs, Z.

2009-04-01

Recent developments in OSL dating have focussed on the measurement of individual sand-sized grains of quartz. Single-grain dating allows the identification of contaminant grains in a sample and their exclusion before final age determination, and the ability to directly check the stratigraphic integrity of archaeological sequences and address concerns about post-deposition sediment mixing. These benefits result in single-grain OSL ages being both accurate and precise. Even greater precision can be attained by adopting a systematic approach to the collection and analysis of OSL data. This involves one operator using the same OSL stimulation and detection instrument, laboratory radiation sources, calibration standards, and analytical procedures for all samples. By holding these experimental parameters constant, sources of error common to all samples are removed, enabling far greater resolution of the true age structure. This approach was recently used to determine the timing and duration of two bursts of Middle Stone Age technological and behavioural innovation - the Still Bay (SB) and Howieson's Poort (HP) - in southern Africa. These distinctive artefacts are associated with the first evidence for symbols and personal ornaments, and may have been the catalyst for the expansion of Homo sapiens populations in Africa 80,000-60,000 years ago and for the subsequent migration of modern humans out of Africa. Testing such hypotheses, and the putative role of climate change, has been hampered by poor age constraints for the HP and SB industries. Previous attempts to resolve the start and end dates of these industries had been largely obscured by the chronological' haze' arising from a variety of different materials being dated by different methods using different equipment, calibration standards, measurement procedures and techniques of data analysis. By clearing this haze and placing all ages on a common timescale, we were able to constrain the timing of the SB and HP, and the gap between them, to better than 3000 years at the 95% confidence interval. Both industries occur within the interval of population expansions in Africa inferred from genetic studies. A meta-analysis shows that our new ages are consistent with previous estimates but are more precise, revealing a lack of spatial patterning of the HP and SB across varied climatic and ecological zones. We find a temporal coincidence with major swings in climate, but not uniquely with these industries. Environmental factors may, therefore, have been responsible for episodic occupation of rock shelters, but were not the forcing mechanism behind the emergence of modern human behaviour.

New age estimations for the western outer city wall of ancient Tayma (NW Saudi Arabia) based on OSL and radiocarbon data and geomorphologic evidence

NASA Astrophysics Data System (ADS)

Engel, M.; Klasen, N.; Brückner, H.; Eichmann, R.; Hausleiter, A.; Al-Najem, M. H.; Al-Said, S. F.; Schneider, P. I.

2009-04-01

Since 2004 tremendous progress has been achieved in deciphering the cultural genesis of the Tayma oasis (NW Saudi Arabia), due to the joint investigations of the German Archaeological Institute Berlin (DAI), the General Commission for Tourism and Antiquities, Kingdom of Saudi Arabia, and the Department of Archaeology and Epigraphy, King Saud University Riyadh. Nevertheless, archaeological research is still suffering from a lacking locally-based absolute chronology of buildings. The pattern of ancient constructions at Tayma is dominated by a prominent city wall system surrounding the ancient town center (Qraya) and stretching 15 km around the oasis. Its internal structure indicates several building periods, i.e. phases of wall modification or extension of the entire system. So far, according to silex and carnelian fragments included in the mud bricks and a previous 14C age of charcoal remains from the central excavation district (wall section at Area A), an initial construction date of the wall between the late 3rd and the early 2nd millennium BC seemed likely. At the excavated western outer city wall a new systematic dating approach - combining the optically stimulated luminescence (OSL) and 14C methods - has been applied to generate a reliable age for the oldest branch of the wall system which nowadays is covered by aeolian sand. The dune deposit is genetically related to the existence of the wall and, therefore, dating its accumulation provides termini ante quem for the construction of the wall. Five OSL dates were generated from the dune deposit providing ages between 4,900 and 3,500 yrs. Two radiocarbon ages support the dating sequence and also contribute to its consistency. By combining the results with geomorphologic evidence we draw the following conclusions: Initial settlement activities at Qraya were accompanied by a regulation of wadi dynamics and the construction of the outer city wall, indicated by the abrupt boundary between the pre-settlement alluvial silt and the overlying wall-related dune deposit. According to the OSL and 14C dating results from this deposit, the wall section at C1 (western part of the ancient settlement, north of Area A) dates back to the middle of the 3rd millennium BC or even earlier. Furthermore, the burying of the still existing remains of the city wall at C1 by sand was already completed at the beginning of the 2nd millennium BC.

Use of the QR Reader to Provide Real-Time Evaluation of Residents' Skills Following Surgical Procedures.

PubMed

Reynolds, Kellin; Barnhill, Danny; Sias, Jamie; Young, Amy; Polite, Florencia Greer

2014-12-01

A portable electronic method of providing instructional feedback and recording an evaluation of resident competency immediately following surgical procedures has not previously been documented in obstetrics and gynecology. This report presents a unique electronic format that documents resident competency and encourages verbal communication between faculty and residents immediately following operative procedures. The Microsoft Tag system and SurveyMonkey platform were linked by a 2-D QR code using Microsoft QR code generator. Each resident was given a unique code (TAG) embedded onto an ID card. An evaluation form was attached to each resident's file in SurveyMonkey. Postoperatively, supervising faculty scanned the resident's TAG with a smartphone and completed the brief evaluation using the phone's screen. The evaluation was reviewed with the resident and automatically submitted to the resident's educational file. The evaluation system was quickly accepted by residents and faculty. Of 43 residents and faculty in the study, 38 (88%) responded to a survey 8 weeks after institution of the electronic evaluation system. Thirty (79%) of the 38 indicated it was superior to the previously used handwritten format. The electronic system demonstrated improved utilization compared with paper evaluations, with a mean of 23 electronic evaluations submitted per resident during a 6-month period versus 14 paper assessments per resident during an earlier period of 6 months. This streamlined portable electronic evaluation is an effective tool for direct, formative feedback for residents, and it creates a longitudinal record of resident progress. Satisfaction with, and use of, this evaluation system was high.

Use of the QR Reader to Provide Real-Time Evaluation of Residents' Skills Following Surgical Procedures

PubMed Central

Reynolds, Kellin; Barnhill, Danny; Sias, Jamie; Young, Amy; Polite, Florencia Greer

2014-01-01

Background A portable electronic method of providing instructional feedback and recording an evaluation of resident competency immediately following surgical procedures has not previously been documented in obstetrics and gynecology. Objective This report presents a unique electronic format that documents resident competency and encourages verbal communication between faculty and residents immediately following operative procedures. Methods The Microsoft Tag system and SurveyMonkey platform were linked by a 2-D QR code using Microsoft QR code generator. Each resident was given a unique code (TAG) embedded onto an ID card. An evaluation form was attached to each resident's file in SurveyMonkey. Postoperatively, supervising faculty scanned the resident's TAG with a smartphone and completed the brief evaluation using the phone's screen. The evaluation was reviewed with the resident and automatically submitted to the resident's educational file. Results The evaluation system was quickly accepted by residents and faculty. Of 43 residents and faculty in the study, 38 (88%) responded to a survey 8 weeks after institution of the electronic evaluation system. Thirty (79%) of the 38 indicated it was superior to the previously used handwritten format. The electronic system demonstrated improved utilization compared with paper evaluations, with a mean of 23 electronic evaluations submitted per resident during a 6-month period versus 14 paper assessments per resident during an earlier period of 6 months. Conclusions This streamlined portable electronic evaluation is an effective tool for direct, formative feedback for residents, and it creates a longitudinal record of resident progress. Satisfaction with, and use of, this evaluation system was high. PMID:26140128

Historical files from Federal government mineral exploration-assistance programs, 1950 to 1974

USGS Publications Warehouse

Frank, David G.

2010-01-01

Congress enacted the Defense Production Act in 1950 to provide funding and support for the exploration and development of critical mineral resources. From 1950 to 1974, three Department of the Interior agencies carried out this mission. Contracts with mine owners provided financial assistance for mineral exploration on a joint-participation basis. These contracts are documented in more than 5,000 'dockets' now archived online by the U.S. Geological Survey. This archive provides access to unique and difficult to recreate information, such as drill logs, assay results, and underground geologic maps, that is invaluable to land and resource management organizations and the minerals industry. An effort to preserve the data began in 2009, and the entire collection of dockets was electronically scanned. The scanning process used optical character recognition (OCR) when possible, and files were converted into Portable Document Format (.pdf) files, which require Adobe Reader or similar software for viewing. In 2010, the scans were placed online (http://minerals.usgs.gov/dockets/) and are available to download free of charge.

Adobe acrobat: an alternative electronic teaching file construction methodology independent of HTML restrictions.

PubMed

Katzman, G L

2001-03-01

The goal of the project was to create a method by which an in-house digital teaching file could be constructed that was simple, inexpensive, independent of hypertext markup language (HTML) restrictions, and appears identical on multiple platforms. To accomplish this, Microsoft PowerPoint and Adobe Acrobat were used in succession to assemble digital teaching files in the Acrobat portable document file format. They were then verified to appear identically on computers running Windows, Macintosh Operating Systems (OS), and the Silicon Graphics Unix-based OS as either a free-standing file using Acrobat Reader software or from within a browser window using the Acrobat browser plug-in. This latter display method yields a file viewed through a browser window, yet remains independent of underlying HTML restrictions, which may confer an advantage over simple HTML teaching file construction. Thus, a hybrid of HTML-distributed Adobe Acrobat generated WWW documents may be a viable alternative for digital teaching file construction and distribution.

Development and analytical performance evaluation of FREND-SAA and FREND-Hp

NASA Astrophysics Data System (ADS)

Choi, Eunha; Seong, Jihyun; Lee, Seiyoung; Han, Sunmi

2017-07-01

The FREND System is a portable cartridge reader, quantifying analytes by measuring laser-induced fluorescence in a single-use reagent cartridge. The objective of this study was to evaluate FREND-SAA and FREND-Hp assays. The FREND-SAA and Hp assays were standardized to the WHO and IFCC reference materials. Analytical performance studies of Precision, Linearity, Limits of Detections, Interferences, and Method Comparisons for both assays were performed according to the CLSI guidelines. Both assays demonstrated acceptable imprecision of %CV in three different levels of samples. The linearity of the assays was found to be acceptable (SAA 5 150 mg/L, Hp 30 400 mg/dL). The detection limits were 3.8 mg/L (SAA) and 10.2 mg/dL (Hp). No significant interference and no significant deviation from linearity was found in the both comparison studies. In conclusion, NanoEnTek's FREND-SAA and Hp assays represent rapid, accurate and convenient means to quantify SAA and Hp in human serum on FREND system.

Disposable luciferase-based microfluidic chip for rapid assay of water pollution.

PubMed

Denisov, Ivan; Lukyanenko, Kirill; Yakimov, Anton; Kukhtevich, Igor; Esimbekova, Elena; Belobrov, Peter

2018-06-21

In the present study, we demonstrate the use of a disposable luciferase-based microfluidic bioassay chip for environmental monitoring and methods for fabrication. The designed microfluidic system includes a chamber with immobilized enzymes of bioluminescent bacteria Photobacterium leiognathi and Vibrio fischeri and their substrates, which dissolve after the introduction of the water sample and thus activate bioluminescent reactions. Limits of detection for copper (II) sulfate, 1,3-dihydroxybenzene and 1,4-benzoquinone for the proposed microfluidic biosensor measured 3 μM, 15 mM, and 2 μM respectively, and these values are higher or close to the level of conventional environmental biosensors based on lyophilized bacteria. Approaches for entrapment of enzymes on poly(methyl methacrylate) (PMMA) plates using a gelatin scaffold and solvent bonding of PMMA chip plates under room temperature were suggested. The proposed microfluidic system may be used with some available luminometers and future portable luminescence readers. © 2018 John Wiley & Sons, Ltd.

Aptamer-Nanoparticle Strip Biosensor for Rapid and Sensitive Detection of Cancer Cells

PubMed Central

Mao, Xun; Phillips, Joseph A.; Xu, Hui; Tan, Weihong; Zeng, Lingwen; Liu, Guodong

2009-01-01

We report an aptamer-nanoparticle strip biosensor (ANSB) for the rapid, specific, sensitive and low-cost detection of circulating cancer cells. Known for their high specificity and affinity, aptamers were first selected from live cells by the cell-SELEX (systematic evolution of ligands by exponential enrichment) process. When next combined with the unique optical properties of gold nanoparticles (Au-NPs), ANSBs were prepared on a lateral flow device. Ramos cells were used as a model target cell to demonstrate proof of principle. Under optimal conditions, the ANSB was capable of detecting a minimum of 4000 Ramos cells without instrumentation (visual judgment) and 800 Ramos cells with a portable strip reader within 15 minutes. Importantly, ANSB has successfully detected Ramos cells in human blood, thus providing a rapid, sensitive and low-cost quantitative tool for the detection of circulating cancer cells. ANSB therefore shows great promise for in-field and point-of-care cancer diagnosis and therapy. PMID:19904989

Microfluidic device for novel breast cancer screening by blood test using miRNA beacon probe.

PubMed

Salim, Bindu; Athira, M V; Kandaswamy, A; Vijayakumar, Madhulika; Saravanan, T; Sairam, Thiagarajan

2017-09-30

Breast cancer is identified as the highest cause of death in women suffering from cancer. Early diagnosis is the key to increase the survival of breast cancer victims. Molecular diagnosis using biomarkers have advanced much in the recent years. The cost involved in such diagnosis is not affordable for most of the population. The concept being investigated here is to realize a simple diagnosis system for screening cancer by way of a blood test utilizing a miRNA based biomarker with a complementary molecular beacon probe. A microfluidic platform was designed and attached with a fluorescence reader, which is portable and cost effective. Experiments were performed with 51 blood samples of which 30 were healthy and 21 were positive for breast cancer, collected against institutional human ethical clearance, IHEC 16/180-7-9-2016. miRNA 21 was chosen as the biomarker because it is overexpressed 4-fold in the serum of breast cancer patients. This work involved design of an experiment to prove the concept of miRNA over expression followed by detection of miRNA 21 using the microfluidic platform attached with a fluorescence reader and validation of the results using quantitative Real Time Polymerase Chain Reaction (qRT-PCR). The results obtained from the microfluidic device concurred with qRT-PCR results. The device is suitable for point-of-care application in a mass-screening programme. The study also has revealed that the stage of the cancer could be indicated by this test, which will be further useful for deciding a therapeutic regime.

Developing a Tool for the Location Optimization of the Alert Aircraft with Changing Threat Anticipation

DTIC Science & Technology

2009-03-01

encountered. From individuals to large industries , people deal with such problems in order to maximize the benefit and gain. Third, the effect of the...Format”. http://www.cenapad.unicamp.br/ parque /manuais/OSL/oslweb/features/featur11.htm 17 December 2008 Chhajed, Dilip, Richard L. Francis, and

Open Simulation Laboratories [Guest editors' introduction

DOE PAGES

Alexander, Francis J.; Meneveau, Charles

2015-09-01

The introduction for the special issue on open simulation laboratories, the guest editors describe how OSLs will become more common as their potential is better understood and they begin providing access to valuable datasets to much larger segments of the scientific community. Moreover, new analysis tools and ways to do science will inevitably develop as a result.

The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere.

PubMed

Yang, Zhen; Chen, Bo; Zhuo, Weihai; Fan, Dunhuang; Zhao, Chao; Zhang, Yu

2015-12-01

For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of (137)Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmic rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account.

Optically- and thermally-stimulated luminescences of Ce-doped SiO2 glasses prepared by spark plasma sintering

NASA Astrophysics Data System (ADS)

Okada, Go; Kasap, Safa; Yanagida, Takayuki

2016-11-01

Rare-earth doped phosphors have been used in many applications including radiation measurements. In the latter applications, the radiation photons are converted to light so that we can indirectly detect the radiation using a conventional photodetector. In this work, we have prepared and characterized a Ce-doped SiO2 glass for dosimeter applications. Unlike conventional techniques such as sol-gel synthesis, the sample was prepared by spark plasma sintering. Although the PL emission seems to be only from the Ce3+ ions in the structure, due to the X-ray induced luminescence, we have also observed optically-stimulated luminescence (OSL), and thermally-stimulated luminescence (TSL), owing to a pair of silylenes and a set of dioxasilirane and silylene in addition to Ce3+. We have measured the detector response vs irradiation dose for both the OSL and TSL. The detector response in both cases is linear over the dose range from at least 1 mGy to 2 Gy. Particularly, the sensitivity of TSL is so high that it should be considered to be a good candidate for practical applications.

The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhen; Chen, Bo, E-mail: bochenfys@fudan.edu.cn; Zhuo, Weihai

For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of {sup 137}Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmicmore » rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account.« less

Athermal fading of luminescence in Al2 O3 ceramic substrates

NASA Astrophysics Data System (ADS)

Terry, Ian; Kouroukla, Eftychia; Bailiff, Ian K.

2015-03-01

Retrospective dosimetry aims to reconstruct ionising radiation dose to populations following a radiological incident using materials not designed for that purpose. Sintered alumina ceramic can function as a dosimeter with its luminescence properties and related trapped charge storage mechanism. Its widespread use as a substrate in surface mount devices and incorporation in devices such as mobile phones make it a ubiquitous potential dosimeter. We investigated the optically (OSL) and thermally (TL) stimulated luminescence properties of sintered alumina substrates. In contrast to their single crystal analogue developed for personal dosimetry, Al2O3:C, the substrates exhibit a significant loss of trapped charge (fading) within hours following irradiation at RT that seriously limits their utility for dosimetry over an extended timescale. The fading rates of OSL and TL signals of 0402 resistors were analysed under various storage conditions (time and temperature), complemented by a study of their microstructure. The results support a model of athermal loss of trapped charge due to electron tunnelling from trapping states; this contrasting behaviour is attributed to a physical modification of the trap environment arising from the manufacturing process.

The responses of three kinds of passive dosimeters to secondary cosmic rays in the lower atmosphere

NASA Astrophysics Data System (ADS)

Yang, Zhen; Chen, Bo; Zhuo, Weihai; Fan, Dunhuang; Zhao, Chao; Zhang, Yu

2015-12-01

For accurate measurements of the secondary cosmic rays by using passive dosimeters, the relative responses of the thermoluminescence dosimeter (TLD), optically stimulated luminescence (OSL) dosimeter, and radiophotoluminescent glass dosimeter (RPLGD) were studied. The cosmic-ray shower generator was used to simulate the secondary cosmic rays at the sea level. Monte Carlo simulations were performed to calculate the air kerma and absorbed doses in each kind of dosimeter. The results showed that compared with their responses to gamma rays of 137Cs, the relative responses of the TLD, OSL, and RPLGD were 0.786, 0.707, and 0.735 to the hard component of cosmic rays, respectively, and the values were 0.904, 0.838, and 0.857 to the soft component of cosmic rays, respectively. To verify the simulations results, an in situ measurement with the three kinds of dosimeters was performed at the same place. The results indicated that the secondary cosmic rays monitored with the three kinds of dosimeters were well consistent with each other provided their relative responses were taken into account.

Optimizing a readout protocol for low dose retrospective OSL-dosimetry using household salt.

PubMed

Christiansson, Maria; Mattsson, Sören; Bernhardsson, Christian; Rääf, Christopher L

2012-06-01

The authors' aim has been to find a single aliquot regenerative dose (SAR) protocol that accurately recovers an unknown absorbed dose in the region between 1-250 mGy in household salt. The main investigation has been conducted on a specific mine salt (>98.5% NaCl) intended for household use, using optical stimulation by blue LED (λ = 462 nm). The most accurate dose recovery for this brand of salt is found to be achieved when using Peak Signal Summing (PSS) of the OSL-decay and a preheat temperature of 200°C after the test dose. A SAR protocol for the household salt with preset values of regenerative doses (R1--R5) and a test dose (TED) of 17 mGy is also suggested here. Under laboratory conditions, the suggested protocol recovers unknown absorbed doses in this particular brand within 5% (2 SD) in the dose range between 1-250 mGy. This is a very promising result for low dose applications of household salt as a retrospective dosimeter after a nuclear or radiological event.

The R package 'RLumModel': Simulating charge transfer in quartz

NASA Astrophysics Data System (ADS)

Friedrich, Johannes; Kreutzer, Sebastian; Schmidt, Christoph

2017-04-01

Kinetic models of quartz luminescence have gained an important role for predicting experimental results and for understanding charge transfers in (natural) quartz as well as for other dosimetric materials, e.g., Al2O3:C. We present the R package 'RLumModel', offering an easy-to-use tool for simulating quartz luminescence signals (TL, OSL, LM-OSL and RF) based on five integrated and published parameter sets as well as the possibility to use own parameters. Simulation commands can be created (a) using the Risø Sequence Editor, (b) a built-in SAR sequence generator or (c) self-explanatory keywords for customised sequences. Results can be analysed seamlessly using the R package 'Luminescence' along with a visualisation of concentrations of electrons and holes in every trap/centre as well as in the valence and conduction band during all stages of the simulation. Modelling luminescence signals can help understanding charge transfer processes occurring in nature or during measurements in the laboratory. This will lead to a better understanding of several processes concerning geoscientific questions, because quartz is the second most abundant mineral in the Earth's continental crust.

Rapid and cyclic dust accumulation during MIS 2 in Central Asia inferred from loess OSL dating and grain-size analysis.

PubMed

Li, Yun; Song, Yougui; Lai, Zhongping; Han, Li; An, Zhisheng

2016-09-02

Due to lack of reliable proxies from the Westerlies-dominant region, the strength change of Northern Hemisphere Westerlies remains poorly understood. The aim of this study is to provide a reliable paleoclimatic proxy about the Northern Hemisphere Westerlies change. Here we report a 30.7 m thick loess section from the Ili basin directly controlled by the Westerlies. Based on optically stimulated luminescence (OSL) and high resolution grain-size records, we reconstruct the change history of the Westerlies strength during the last glacial period (mainly Marine Isotope Stages 2, MIS2), being similar with the Westerlies index recorded in the Qinghai Lake sediments. Within error limits, all ages are in stratigraphic order. We further compare the climatic records among the Ili loess, Qinghai Lake and the NGRIP, their similarity shows a good climatic coupling relationship among the Central Asia, East Asia and the North Atlantic, and the Westerlies plays a critical influence in transporting the North Atlantic signal to Central and East Asia.

The Joy of Playing with Oceanographic Data

NASA Astrophysics Data System (ADS)

Smith, A. T.; Xing, Z.; Armstrong, E. M.; Thompson, C. K.; Huang, T.

2013-12-01

The web is no longer just an after thought. It is no longer just a presentation layer filled with HTML, CSS, JavaScript, Frameworks, 3D, and more. It has become the medium of our communication. It is the database of all databases. It is the computing platform of all platforms. It has transformed the way we do science. Web service is the de facto method for communication between machines over the web. Representational State Transfer (REST) has standardized the way we architect services and their interfaces. In the Earth Science domain, we are familiar with tools and services such as Open-Source Project for Network Data Access Protocol (OPeNDAP), Thematic Realtime Environmental Distributed Data Services (THREDDS), and Live Access Server (LAS). We are also familiar with various data formats such as NetCDF3/4, HDF4/5, GRIB, TIFF, etc. One of the challenges for the Earth Science community is accessing information within these data. There are community-accepted readers that our users can download and install. However, the Application Programming Interface (API) between these readers is not standardized, which leads to non-portable applications. Webification (w10n) is an emerging technology, developed at the Jet Propulsion Laboratory, which exploits the hierarchical nature of a science data artifact to assign a URL to each element within the artifact. (e.g. a granule file). By embracing standards such as JSON, XML, and HTML5 and predictable URL, w10n provides a simple interface that enables tool-builders and researchers to develop portable tools/applications to interact with artifacts of various formats. The NASA Physical Oceanographic Distributed Active Archive Center (PO.DAAC) is the designated data center for observational products relevant to the physical state of the ocean. Over the past year PO.DAAC has been evaluating w10n technology by webifying its archive holdings to provide simplified access to oceanographic science artifacts and as a service to enable future tools and services development. In this talk, we will focus on a w10n-based system called Distributed Oceanographic Webification Service (DOWS) being developed at PO.DAAC to provide a newer and simpler method for working with observational data artifacts. As a continued effort at PO.DAAC to provide better tools and services to visualize our data, the talk will discuss the latest in web-based data visualization tools/frameworks (such as d3.js, Three.js, Leaflet.js, and more) and techniques for working with webified oceanographic science data in both a 2D and 3D web approach.

Constraining Big Hurricanes: Remotely sensing Galveston Islands' changing coastal landscape from days to millennia

NASA Astrophysics Data System (ADS)

Dougherty, A. J.; Choi, J. H.; Heo, S.; Dosseto, A.

2017-12-01

Climate change models forecast increased storm intensity, which will drive coastal erosion as sea-level rise accelerates with global warming. Over the last five years the largest hurricanes ever recorded in the Pacific (Patricia) and the Atlantic (Irma) occurred as well as the devastation of Harvey. The preceding decade was marked with Super Storm Sandy, Katrina and Ike. A century prior, the deadliest natural disaster in North America occurred as a category 4 hurricane known as `The 1900 Storm' hit Galveston Island. This research aims to contextualize the impact of storms long before infrastructure and historical/scientific accounts documented erosion. Unlike the majority of barrier islands in the US, Galveston built seaward over the Holocene. As the beach prograded it preserved a history of storms and shoreline change over millennia to the present-day. These systems (called prograded barriers) were first studied over 50 years ago using topographic profiles, sediment cores and radiocarbon dating. This research revisits some of these benchmark study sites to augment existing data utilizing state-of-the-art Light Detection and Ranging (LiDAR), Ground Penetrating Radar (GPR), and Optically Stimulated Luminescence (OSL) techniques. In 2016 GPR and OSL data were collected from Galveston Island, with the aim to combine GPR, OSL and LiDAR (GOaL) to extract a high-resolution geologic record spanning 6,000 years. The resulting millennia-scale coastal evolution can be used to contextualize the impact of historic hurricanes over the past century (`The 1900 Storm'), decade (Ike in 2008) and year (now with Harvey). Preliminary results reveal a recent change in shoreline behaviour, and data from Harvey are currently being accessed within the perspective of these initial findings. This dataset will be discussed with respect to the other two benchmark prograded barriers studied in North America: Nayarit Barrier (Mexico) that Hurricane Patricia passed directly over in 2013 and Kiawah Barrier (South Carolina), which was ultimately spared from Hurricane Irma 2017.

Improving the AOAC use-dilution method by establishing a minimum log density value for test microbes on inoculated carriers.

PubMed

Tomasino, Stephen F; Pines, Rebecca M; Hamilton, Martin A

2009-01-01

The AOAC Use-Dilution methods, 955.14 (Salmonella enterica), 955.15 (Staphylococcus aureus), and 964.02 (Pseudomonas aeruginosa), are used to measure the efficacy of disinfectants on hard inanimate surfaces. The methods do not provide procedures to assess log density of the test microbe on inoculated penicylinders (carrier counts). Without a method to measure and monitor carrier counts, the associated efficacy data may not be reliable and repeatable. This report provides a standardized procedure to address this method deficiency. Based on carrier count data collected by four laboratories over an 8 year period, a minimum log density value is proposed to qualify the test results. Carrier count data were collected concurrently with 242 Use-Dilution tests. The tests were conducted on products bearing claims against P. aeruginosa and S. aureus with and without an organic soil load (OSL) added to the inoculum (as specified on the product label claim). Six carriers were assayed per test for a total of 1452 carriers. All 242 mean log densities were at least 6.0 (geometric mean of 1.0 x 10(6) CFU/carrier). The mean log densities did not exceed 7.5 (geometric mean of 3.2 x 10(7) CFU/carrier). For all microbes and OSL treatments, the mean log density (+/- SEM) was 6.7 (+/- 0.07) per carrier (a geometric mean of 5.39 x 10(6) CFU/carrier). The mean log density for six carriers per test showed good repeatability (0.29) and reproducibility (0.32). A minimum mean log density of 6.0 is proposed as a validity requirement for S. aureus and P. aeruginosa. The minimum level provides for the potential inherent variability that may be experienced by a wide range of laboratories and the slight effect due to the addition of an OSL. A follow-up report is planned to present data to support the carrier count procedure and carrier counts for S. enterica.

An integrated OSL chronology, sedimentology and geochemical approach to loess deposits from Tuoji Island, Shandong Province: Implications for the late quaternary paleoenvironment in East China

NASA Astrophysics Data System (ADS)

Xu, Shujian; Kong, Fanbiao; Jia, Guangju; Miao, Xiaodong; Ding, Xinchao

2018-04-01

The Tuoji II (TJII) section on the Miaodao Islands in the Bohai Sea is a representative aeolian section off China's east coast. This study applied optically stimulated luminescence (OSL) dating, conducted grain size analysis, and examined major and trace element compositions, to investigate the loess-paleosol sequences. The OSL ages at depths of 0.6, 1.8, 2.8, 3.8, and 4.8 m were determined as 14.4 ± 0.4, 16.7 ± 1.3, 20.8 ± 1.0, 40.9 ± 1.5, and 47.9 ± 3.7 ka, respectively. It was projected that the loess started to accumulate at ca. 62.6 ka, according to presumed depositional rates. In this study, typical aeolian deposits elsewhere including the Luochuan (LC), Xiashu (XS), Wushan (WS), and Xifeng (XF) sections were compared with TJII section here. The results showed similarity in the geochemical characteristics of the deposits from the different areas of China and normalized upper continental crust, indicating aeolian origin of this island loess. In comparison with the LC, XS, WS, and XF samples, the aeolian deposits of the TJII section have higher concentrations of TiO2 and Zr and lower concentrations of Al2O3, Rb, and Ni, and they have higher SiO2/Al2O3 and TiO2/Al2O3 ratios and lower Al2O3/Na2O and Ba/Sr ratios. These features indicate the dust materials of the TJII section were derived from local sources of well-mixed sedimentary protoliths. Our results support the suggestion that paleoclimatic change and the evolution of aeolian sediments were controlled primarily by variation of the East Asian summer monsoon and sea level change.

Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition.

PubMed

Dong, Yajie; Wu, Naiqin; Li, Fengjiang; Huang, Linpei; Wen, Wenwen

2015-01-01

The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS) has previously been assumed to be synchronous with the Marine Isotope Stage (MIS) 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP). However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR) protocol to the 45-63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL) samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3-4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast.

Time-Transgressive Nature of the Magnetic Susceptibility Record across the Chinese Loess Plateau at the Pleistocene/Holocene Transition

PubMed Central

Dong, Yajie; Wu, Naiqin; Li, Fengjiang; Huang, Linpei; Wen, Wenwen

2015-01-01

The loess stratigraphic boundary at the Pleistocene/Holocene transition defined by the magnetic susceptibility (MS) has previously been assumed to be synchronous with the Marine Isotope Stage (MIS) 2/1 boundary, and approximately time-synchronous at different sections across the Chinese Loess Plateau (CLP). However, although this assumption has been used as a basis for proxy-age model of Chinese loess deposits, it has rarely been tested by using absolute dating methods. In this study, we applied a single-aliquot regenerative-dose (SAR) protocol to the 45–63 μm quartz grain-size fraction to derive luminescence ages for the last glacial and Holocene sections of three loess sections on a transect from southeast to northwest across the CLP. Based on the 33 closely spaced optically stimulated luminescence (OSL) samples from the three sections, OSL chronologies were established using a polynomial curve fit at each section. Based on the OSL chronology, the timing of the Pleistocene/Holocene boundary, as defined by rapid changes in MS values, is dated at ~10.5 ka, 8.5 ka and 7.5 ka in the Yaoxian section, Jingchuan and Huanxian sections respectively. These results are clearly inconsistent with the MIS 2/1 boundary age of 12.05 ka, and therefore we conclude that the automatic correlation of the Pleistocene/Holocene transition, as inferred from the MS record, with the MIS 2/1 boundary is incorrect. The results clearly demonstrate that the marked changes in MS along the southeast to northwest transect are time-transgressive among the different sites, with the timing of significant paleosol development as indicated by the MS record being delayed by 3–4 ka in the northwest compared to the southeast. Our results suggest that this asynchronous paleosol development during the last deglacial was caused by the delayed arrival of the summer monsoon in the northwest CLP compared to the southeast. PMID:26186443

Development of an objective dose distribution analysis method for OSL dating and pilot studies for planetary applications

NASA Astrophysics Data System (ADS)

Lepper, Kenneth Errol

Scope and method of study. Part I: In its simplest expression a luminescence age is the natural absorbed radiation dose (De) divided by the in-situ dose rate. The experimental techniques of Optically Stimulated Luminescence (OSL) dating have evolved to the point were hundreds of Des, and therefore depositional ages can be quickly and conveniently determined for a single sediment sample. The first major objective of this research was to develop an objective analysis method for analyzing dose distribution data and selecting an age-representative dose (Dp). The analytical method was developed based on dose data sets collected from 3 eolian and 3 fluvial sediment samples from Central Oklahoma. Findings and conclusions. Part I: An objective method of presenting the dose distribution data, and a mathematically rigorous means of determining the Dp, as well as a statistically meaningful definition of the uncertainty in Dp have been proposed. The concept of experimental error deconvolution was introduced. In addition a set of distribution shape parameters to facilitate comparison among samples have been defined. These analytical techniques hold the potential to greatly enhance the accuracy and utility of OSL dating for young fluvial sediments. Scope and method of study. Part II: The second major objective of this research was to propose the application of luminescence dating to sediments on Mars. A set of fundamental luminescence dating properties was evaluated for a martian surface materials analog and a polar deposit contextual analog. Findings and conclusions. Part II: The luminescence signals measured from the analogs were found to have a wide dynamic dose response range with no unusual or prohibitive short-term instabilities and were readily reset by exposure to sunlight. These properties form a stable base for continued investigations toward the development of luminescence dating instruments and procedures for Mars.

Quaternary alluvial fans of Ciudad Juárez, Chihuahua, northern México: OSL ages and implications for climatic history of the region

USGS Publications Warehouse

Zúñiga de León, David; Kershaw, Stephen; Mahan, Shannon

2016-01-01

Alluvial fans formed from sediments derived from erosion of the Juárez Mountains in northernmost México have a significant flood impact on the Ciudad Juárez, which is built on the fan system. The northern part of Ciudad Juárez is the most active; further south, older parts of the fan, upon which the rest of the city is built, were largely eroded by natural processes prior to human habitation and subsequently modified only recently by human construction. Three aeolian sand samples, collected from the uppermost (youngest) parts of the fan system in the city area, in places where human intervention has not disturbed the sediment, and constrain the latest dates of fan building. Depositional ages of the Quaternary alluvial fans were measured using Optically Stimulated Luminescence (OSL) on aeolian sands that have inter-fingered with alluvial fan material. These dates are: a) sample P1, 31 ka; b) sample P2, 41 ka; c) sample P3, 74 ka, between Oxygen Isotope Stages (OIS) 3 to 5. They demonstrate that fan development, in the area now occupied by the city, terminated in the Late Pleistocene, immediately after what we interpret to have been an extended period of erosion without further deposition, lasting from the Late Pleistocene to Holocene. The three dates broadly correspond to global glacial periods, implying that the cool, dry periods may reflect periods of aeolian transport in northern México in between phases that were wetter to form the alluvial fans. Alluvial fan margins inter-finger with fluvial terrace sediments derived from the Río Bravo, indicating an additional component of fan dissection by Río Bravo lateral erosion, presumed to be active during earlier times than our OSL ages, but these are not yet dated. Further dating is required to ascertain the controls on the fan and fluvial system.

Evaluation of external exposures of the population of Ozyorsk, Russia, with luminescence measurements of bricks.

PubMed

Woda, Clemens; Jacob, P; Ulanovsky, A; Fiedler, I; Mokrov, Y; Rovny, S

2009-11-01

Recently discovered historical documents indicate that large releases of noble gases (mainly (41)Ar and radioactive isotopes of Kr and Xe) from the Mayak Production Association (MPA) over the period from 1948 to 1956 may have caused considerable external exposures of both, inhabitants of Ozyorsk and former inhabitants of villages at the upper Techa River. To quantify this exposure, seven brick samples from three buildings in Ozyorsk, located 8-10 km north-northwest from the radioactive gas release points, were taken. The absorbed dose in brick was measured in a depth interval of 3-13 mm below the exposed surface of the bricks by means of the thermoluminescence (TL) and the optically stimulated luminescence (OSL) method. Generally, luminescence properties using TL were more favorable for precise dose determination than using OSL, but within their uncertainties the results from both methods agree well with each other. The absorbed dose due to natural radiation was assessed and subtracted under the assumption of the bricks to be completely dry. The weighted average of the anthropogenic dose for all samples measured by TL and OSL is 10 +/- 9 and 1 +/- 9 mGy, respectively. An upper limit for a possible anthropogenic dose in brick that would not be detected due to the measurement uncertainties is estimated at 24 mGy. This corresponds to an effective dose of about 21 mSv. A similar range of values is obtained in recently published dispersion calculations that were based on reconstructed MPA releases. It is concluded that the release of radioactive noble gases from the radiochemical and reactor plants at Mayak PA did not lead to a significant external exposure of the population of Ozyorsk. In addition, the study demonstrates the detection limit for anthropogenic doses in ca. 60-year-old bricks to be about 24 mGy, if luminescence methods are used.

Dating of river terraces along Lefthand Creek, western High Plains, Colorado, reveals punctuated incision

USGS Publications Warehouse

Foster, Melissa A.; Anderson, Robert S.; Gray, Harrison J.; Mahan, Shannon

2017-01-01

The response of erosional landscapes to Quaternary climate oscillations is recorded in fluvial terraces whose quantitative interpretation requires numerical ages. We investigate gravel-capped strath terraces along the western edge of Colorado's High Plains to constrain the incision history of this shale-dominated landscape. We use ¹⁰Be and ²⁶Al cosmogenic radionuclides (CRNs), optically stimulated luminescence (OSL), and thermally transferred OSL (TT-OSL) to date three strath terraces, all beveled in shale bedrock and then deposited upon by Lefthand Creek, which drains the crystalline core of the Front Range. Our study reveals: (i) a long history (hundreds of thousands of years) of fluvial occupation of the second highest terrace, T2 (Table Mountain), with fluvial abandonment at 92 ± 3 ka; (ii) a brief occupation of a narrow and spatially confined terrace, T3, at 98 ± 7 ka; and (iii) a 10–25 thousand year period of cutting and fluvial occupation of a lower terrace, T4, marked by the deposition of a lower alluvial unit between 59 and 68 ka, followed by deposition of an upper alluvial package at 40 ± 3 ka. In conjunction with other recent CRN studies of strath terraces along the Colorado Front Range (Riihimaki et al., 2006; Dühnforth et al., 2012), our data reveal that long periods of lateral planation and fluvial occupation of strath terraces, sometimes lasting several glacial-interglacial cycles, are punctuated by brief episodes of rapid vertical bedrock incision. These data call into question what a singular terrace age represents, as the strath may be cut at one time (its cutting-age) and the terrace surface may be abandoned at a much later time (its abandonment age), and challenge models of strath terraces that appeal to simple pacing by the glacial-interglacial cycles.

Commissioning optically stimulated luminescence in vivo dosimeters for fast neutron therapy.

PubMed

Young, Lori A; Yang, Fei; Woodworth, Davis; McCormick, Zephyr; Sandison, George

2016-01-01

Clinical in vivo dosimeters intended for use with photon and electron therapies have not been utilized for fast neutron therapy because they are highly susceptible to neutron damage. The objective of this work was to determine if a commercial optically stimulated luminescence (OSL) in vivo dosimetry system could be adapted for use in fast neutron therapy. A 50.5 MeV fast neutron beam generated by a clinical neutron therapy cyclotron was used to irradiate carbon doped aluminum oxide (Al2O3:C) optically simulated luminescence dosimeters (OSLDs) in a solid water phantom under standard calibration conditions, 150 cm SAD, 1.7 cm depth, and 10.3 × 10.0 cm field size. OSLD fading and electron trap depletion studies were performed with the OSLDs irradiated with 20 and 50 cGy and monitored over a 24-h period to determine the optimal time for reading the dosimeters during calibration. Four OSLDs per group were calibrated over a clinical dose range of 0-150 cGy. OSLD measurement uncertainties were lowered to within ±2%-3% of the expected dose by minimizing the effect of transient fading that occurs with neutron irradiation and maintaining individual calibration factors for each dosimeter. Dose dependent luminescence fading extended beyond the manufacturer's recommended 10 min period for irradiation with photon or electron beams. To minimize OSL variances caused by inconsistent fading among dosimeters, the observed optimal time for reading the OSLDs postirradiation was between 30 and 90 min. No field size, wedge factor, or gantry angle dependencies were observed in the OSLDs irradiated by the studied fast neutron beam. Measurements demonstrated that uncertainties less than ±3% were attainable in OSLDs irradiated with fast neutrons under clinical conditions. Accuracy and precision comparable to clinical OSL measurements observed with photons can be achieved by maintaining individual OSLD calibration factors and minimizing transient fading effects.

Commissioning optically stimulated luminescence in vivo dosimeters for fast neutron therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Young, Lori A., E-mail: layoung@uw.edu; Sandison, George; Yang, Fei

Purpose: Clinical in vivo dosimeters intended for use with photon and electron therapies have not been utilized for fast neutron therapy because they are highly susceptible to neutron damage. The objective of this work was to determine if a commercial optically stimulated luminescence (OSL) in vivo dosimetry system could be adapted for use in fast neutron therapy. Methods: A 50.5 MeV fast neutron beam generated by a clinical neutron therapy cyclotron was used to irradiate carbon doped aluminum oxide (Al{sub 2}O{sub 3}:C) optically simulated luminescence dosimeters (OSLDs) in a solid water phantom under standard calibration conditions, 150 cm SAD, 1.7more » cm depth, and 10.3 × 10.0 cm field size. OSLD fading and electron trap depletion studies were performed with the OSLDs irradiated with 20 and 50 cGy and monitored over a 24-h period to determine the optimal time for reading the dosimeters during calibration. Four OSLDs per group were calibrated over a clinical dose range of 0–150 cGy. Results: OSLD measurement uncertainties were lowered to within ±2%–3% of the expected dose by minimizing the effect of transient fading that occurs with neutron irradiation and maintaining individual calibration factors for each dosimeter. Dose dependent luminescence fading extended beyond the manufacturer’s recommended 10 min period for irradiation with photon or electron beams. To minimize OSL variances caused by inconsistent fading among dosimeters, the observed optimal time for reading the OSLDs postirradiation was between 30 and 90 min. No field size, wedge factor, or gantry angle dependencies were observed in the OSLDs irradiated by the studied fast neutron beam. Conclusions: Measurements demonstrated that uncertainties less than ±3% were attainable in OSLDs irradiated with fast neutrons under clinical conditions. Accuracy and precision comparable to clinical OSL measurements observed with photons can be achieved by maintaining individual OSLD calibration factors and minimizing transient fading effects.« less

Thermally assisted OSL application for equivalent dose estimation; comparison of multiple equivalent dose values as well as saturation levels determined by luminescence and ESR techniques for a sedimentary sample collected from a fault gouge

NASA Astrophysics Data System (ADS)

Şahiner, Eren; Meriç, Niyazi; Polymeris, George S.

2017-02-01

Equivalent dose estimation (De) constitutes the most important part of either trap-charge dating techniques or dosimetry applications. In the present work, multiple, independent equivalent dose estimation approaches were adopted, using both luminescence and ESR techniques; two different minerals were studied, namely quartz as well as feldspathic polymineral samples. The work is divided into three independent parts, depending on the type of signal employed. Firstly, different De estimation approaches were carried out on both polymineral and contaminated quartz, using single aliquot regenerative dose protocols employing conventional OSL and IRSL signals, acquired at different temperatures. Secondly, ESR equivalent dose estimations using the additive dose procedure both at room temperature and at 90 K were discussed. Lastly, for the first time in the literature, a single aliquot regenerative protocol employing a thermally assisted OSL signal originating from Very Deep Traps was applied for natural minerals. Rejection criteria such as recycling and recovery ratios are also presented. The SAR protocol, whenever applied, provided with compatible De estimations with great accuracy, independent on either the type of mineral or the stimulation temperature. Low temperature ESR signals resulting from Al and Ti centers indicate very large De values due to bleaching in-ability, associated with large uncertainty values. Additionally, dose saturation of different approaches was investigated. For the signal arising from Very Deep Traps in quartz saturation is extended almost by one order of magnitude. It is interesting that most of De values yielded using different luminescence signals agree with each other and ESR Ge center has very large D0 values. The results presented above highly support the argument that the stability and the initial ESR signal of the Ge center is highly sample-dependent, without any instability problems for the cases of quartz resulting from fault gouge.

OSL Dating and GPR Mapping of Palaeotsunami Inundation: A 4000-Year History of Indian Ocean Tsunamis as recorded in Sri Lanka

NASA Astrophysics Data System (ADS)

Premasiri, Ranjith; Styles, Peter; Shrira, Victor; Cassidy, Nigel; Schwenninger, Jean-Luc

2015-12-01

To evaluate and mitigate tsunami hazard, as long as possible records of inundations and dates of past events are needed. Coastal sediments deposited by tsunamis (tsunamites) can potentially provide this information. However, of the three key elements needed for reconstruction of palaeotsunamis (identification of sediments, dating and finding the inundation distance) the latter remains the most difficult. The existing methods for estimating the extent of a palaeotsunami inundation rely on extensive excavation, which is not always possible. Here, by analysing tsunamites from Sri Lanka identified using sedimentological and paleontological characteristics, we show that their internal dielectric properties differ significantly from surrounding sediments. The significant difference in the value of dielectric constant of the otherwise almost indistinguishable sediments is due to higher water content of tsunamites. The contrasts were found to be sharp and not to erode over thousands of years; they cause sizeable electromagnetic wave reflections from tsunamite sediments, which permit the use of ground-penetrating radar (GPR) to trace their extent and morphology. In this study of the 2004 Boxing Day Indian Ocean tsunami, we use GPR in two locations in Sri Lanka to trace four identified major palaeotsunami deposits for at least 400 m inland (investigation inland was constrained by inaccessible security zones). The subsurface extent of tsunamites (not available without extensive excavation) provides a good proxy for inundation. The deposits were dated using the established method of optically stimulated luminescence (OSL). This dating, partly corroborated by available historical records and independent studies, contributes to the global picture of tsunami hazard in the Indian Ocean. The proposed method of combined GPR/OSL-based reconstruction of palaeotsunami deposits enables estimates of inundation, recurrence and, therefore, tsunami hazard for any sandy coast with identifiable tsunamite deposits. The method could be also used for anchoring and synchronizing chronologies of ancient civilisations adjacent to the ocean shores.

Characteristics of an OSLD in the diagnostic energy range.

PubMed

Al-Senan, Rani M; Hatab, Mustapha R

2011-07-01

Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. NanoDot OSL dosimeters (OSLDs) were used in this study, which started with testing the homogeneity of a new packet of nanoDots. Reproducibility and the effect of optical treatment (bleaching) were then examined, followed by an investigation of the effect of accumulated dose on the OSLD indicated doses. OSLD linearity, angular dependence, and energy dependence were also studied. Furthermore, comparison with LiF:Mg,Ti TLD chips using standard CT dose phantoms at 80 and 120 kVp settings was performed. Batch homogeneity showed a coefficient of variation of <5%. Single-irradiation measurements with bleaching after each OSL readout was found to be associated with a 3.3% reproducibility (one standard deviation measured with a 8 mGy test dose), and no systematic change in OSLDs sensitivity could be noted from measurement to measurement. In contrast, the multiple-irradiation readout without bleaching in between measurements was found to be associated with an uncertainty (using a 6 mGy test dose) that systematically increased with accumulated dose, reaching 42% at 82 mGy. Good linearity was shown by nanoDots under general x-ray, CT, and mammography units with an R2 > 0.99. The angular dependence test showed a drop of approximately 70% in the OSLD response at 90 degrees in mammography (25 kVp). With the general radiography unit, the maximum drop was 40% at 80 kVp and 20% at 120 kVp, and it was only 10% with CT at both 80 and 120 kVp. The energy dependence study showed a range of ion chamber-to-OSLDs ratios between 0.81 and 1.56, at the energies investigated (29-62 keV). A paired t-test for comparing the OSLDs and TLDs showed no significant variation (p > 0.1). OSLDs exhibited good batch homogeneity (<5%) and reproducibility (3.3%), as well as a linear response. In addition, they showed no statistically significant difference with TLDs in CT measurements (p > 0.1). However, high uncertainty (42%) in the dose estimate was found as a result of relatively high accumulated dose. Furthermore, nanoDots showed high angular dependence (up to 70%) in low kVp techniques. Energy dependence of about 60% was found, and correction factors were suggested for the range of energies investigated. Therefore, if angular and energy dependences are taken into consideration and the uncertainty associated with accumulated dose is avoided, OSLDs (nanoDots) can be suitable for use as point dosimeters in diagnostic settings.

Multiphase materials with lignin. IV. Blends of hydroxypropyl cellulose with lignin

Treesearch

Timothy G. Rials; Wolfgang G. Glasser

1989-01-01

Polymer blends of hydroxypropyl cellulose (HPC) and organosolv lignin (OSL) were prepared by mixing in solutions of both pyridine and dioxane, and casting as films, and by mixing in the melt followed by extrusion. All preparations exhibited partial miscibility as evidenced by a single Tg up to a composition of 40 wt % lignin above which phase...

Development of a First Sergeant Guidebook

DTIC Science & Technology

1984-02-01

ANtSCLE IS 0IO. 0.)O~Iu CjCOURt-PItOAL ACTIOft *EVESR00S(@6 IS VNICE OSL Cmom T20vs %I T’a.s F& mc’ JISECTION It OIMPN REPORT FILL INinvestigation...use of radiation dosimeters and the~ principles ofrdainexposure cnrl 9. Recognize the existence of a chemical hazard and indications of a biological

Operation JANGLE. Airborne Particle Studies. Project 2.5a-1

DTIC Science & Technology

1979-10-01

dosimeter film, type 552. After an exposure of approxi- mately one month, the cones were removed and the film processed. This radioautograph (Fig...giving -•..eght to the idea that the base surge was Co,• osled of small particlej. 5.3 RADIOACTIVITY AS A FINCTION OF PARTICLE SIZE It was hoped that the

A Representative Survey of U.S. Space Systems and Methods for Estimating Their Costs

DTIC Science & Technology

1992-11-01

68 TETR.I Radose: U.S. Air Force satellites carrying radiation dosimeters Radose 06/15/63 07/30/63 Radose-5E1 09/28/63 SN39 Radose-5EIA 12105/63... OSL Orbiting Solar Laboratory OSO Orbiting Solar Observatory OSSA Office of Space Science and Applications OSSE Oriented Scintillation Spectrometer

Performance assessment of multi-frequency processing of ICU chest images for enhanced visualization of tubes and catheters

NASA Astrophysics Data System (ADS)

Wang, Xiaohui; Couwenhoven, Mary E.; Foos, David H.; Doran, James; Yankelevitz, David F.; Henschke, Claudia I.

2008-03-01

An image-processing method has been developed to improve the visibility of tube and catheter features in portable chest x-ray (CXR) images captured in the intensive care unit (ICU). The image-processing method is based on a multi-frequency approach, wherein the input image is decomposed into different spatial frequency bands, and those bands that contain the tube and catheter signals are individually enhanced by nonlinear boosting functions. Using a random sampling strategy, 50 cases were retrospectively selected for the study from a large database of portable CXR images that had been collected from multiple institutions over a two-year period. All images used in the study were captured using photo-stimulable, storage phosphor computed radiography (CR) systems. Each image was processed two ways. The images were processed with default image processing parameters such as those used in clinical settings (control). The 50 images were then separately processed using the new tube and catheter enhancement algorithm (test). Three board-certified radiologists participated in a reader study to assess differences in both detection-confidence performance and diagnostic efficiency between the control and test images. Images were evaluated on a diagnostic-quality, 3-megapixel monochrome monitor. Two scenarios were studied: the baseline scenario, representative of today's workflow (a single-control image presented with the window/level adjustments enabled) vs. the test scenario (a control/test image pair presented with a toggle enabled and the window/level settings disabled). The radiologists were asked to read the images in each scenario as they normally would for clinical diagnosis. Trend analysis indicates that the test scenario offers improved reading efficiency while providing as good or better detection capability compared to the baseline scenario.

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health.

PubMed

Rasooly, Reuven; Bruck, Hugh Alan; Balsam, Joshua; Prickril, Ben; Ossandon, Miguel; Rasooly, Avraham

2016-05-17

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings.

Improving the Sensitivity and Functionality of Mobile Webcam-Based Fluorescence Detectors for Point-of-Care Diagnostics in Global Health

PubMed Central

Rasooly, Reuven; Bruck, Hugh Alan; Balsam, Joshua; Prickril, Ben; Ossandon, Miguel; Rasooly, Avraham

2016-01-01

Resource-poor countries and regions require effective, low-cost diagnostic devices for accurate identification and diagnosis of health conditions. Optical detection technologies used for many types of biological and clinical analysis can play a significant role in addressing this need, but must be sufficiently affordable and portable for use in global health settings. Most current clinical optical imaging technologies are accurate and sensitive, but also expensive and difficult to adapt for use in these settings. These challenges can be mitigated by taking advantage of affordable consumer electronics mobile devices such as webcams, mobile phones, charge-coupled device (CCD) cameras, lasers, and LEDs. Low-cost, portable multi-wavelength fluorescence plate readers have been developed for many applications including detection of microbial toxins such as C. Botulinum A neurotoxin, Shiga toxin, and S. aureus enterotoxin B (SEB), and flow cytometry has been used to detect very low cell concentrations. However, the relatively low sensitivities of these devices limit their clinical utility. We have developed several approaches to improve their sensitivity presented here for webcam based fluorescence detectors, including (1) image stacking to improve signal-to-noise ratios; (2) lasers to enable fluorescence excitation for flow cytometry; and (3) streak imaging to capture the trajectory of a single cell, enabling imaging sensors with high noise levels to detect rare cell events. These approaches can also help to overcome some of the limitations of other low-cost optical detection technologies such as CCD or phone-based detectors (like high noise levels or low sensitivities), and provide for their use in low-cost medical diagnostics in resource-poor settings. PMID:27196933

Quantification of Plant Chlorophyll Content Using Google Glass

PubMed Central

Cortazar, Bingen; Koydemir, Hatice Ceylan; Tseng, Derek; Feng, Steve; Ozcan, Aydogan

2015-01-01

Measuring plant chlorophyll concentration is a well-known and commonly used method in agriculture and environmental applications for monitoring plant health, which also correlates with many other plant parameters including, e.g., carotenoids, nitrogen, maximum green fluorescence, etc. Direct chlorophyll measurement using chemical extraction is destructive, complex and time-consuming, which has led to the development of mobile optical readers, providing non-destructive but at the same time relatively expensive tools for evaluation of plant chlorophyll levels. Here we demonstrate accurate measurement of chlorophyll concentration in plant leaves using Google Glass and a custom-developed software application together with a cost-effective leaf holder and multi-spectral illuminator device. Two images, taken using Google Glass, of a leaf placed in our portable illuminator device under red and white (i.e., broadband) light-emitting-diode (LED) illumination are uploaded to our servers for remote digital processing and chlorophyll quantification, with results returned to the user in less than 10 seconds. Intensity measurements extracted from the uploaded images are mapped against gold-standard colorimetric measurements made through a commercially available reader to generate calibration curves for plant leaf chlorophyll concentration. Using five plant species to calibrate our system, we demonstrate that our approach can accurately and rapidly estimate chlorophyll concentration of fifteen different plant species under both indoor and outdoor lighting conditions. This Google Glass based chlorophyll measurement platform can display the results in spatiotemporal and tabular forms and would be highly useful for monitoring of plant health in environmental and agriculture related applications, including e.g., urban plant monitoring, indirect measurements of the effects of climate change, and as an early indicator for water, soil, and air quality degradation. PMID:25669673

Radiographic Detectability of Retained Neuropatties in a Cadaver Model.

PubMed

Luo, Wangjian Thomas; Almack, Robert; Mawson, John B; Cochrane, David Douglas

2015-08-01

Counts are the commonest method used to ensure that all sponges and neuropatties are removed from a surgical site before closure. When the count is not reconciled, plain radiographs of the operative site are taken to determine whether the missing patty has been left in the wound. The purpose of this study was to describe the detectability of commonly used neuropatties in the clinical setting using digital technologies. Neuropatties were implanted into the anterior and posterior cranial fossae and the thoracolumbar extradural space of a mature male cadaver. Four neuropatty sizes were used: 3 × 1 in, 2 × ½ in, ½ × ½ in, and ¼ × ¼ in. Neuropatties, with size and location chosen at random, were placed in the surgical sites and anteroposterior/posterior-anterior and lateral radiographs were taken using standard portable digital radiographic equipment. Six clinicians reviewed the digital images for the presence or absence of neuropatties. The readers were not aware of the number and size of the patties that were included in each image. The detectability of neuropatties is dependent on the size of the neuropatty's radiopaque marker and the operative site. Neuropatties measuring 2 × ½ in and 3 × 1 in were detected reliably regardless of the operative site. ¼ × ¼ in neuropatties were poorly detected by neurosurgeons and radiologists in all three operative sites. Readers of various experience and background were similar in their ability to detect neuropatties under these conditions. Under simulated operating room conditions and using currently available neuropatties and plain radiograph imaging technology, small ¼-in and ½-in neuropatties are poorly visible/detectable on digital images. Copyright © 2015 Elsevier Inc. All rights reserved.

Quantification of plant chlorophyll content using Google Glass.

PubMed

Cortazar, Bingen; Koydemir, Hatice Ceylan; Tseng, Derek; Feng, Steve; Ozcan, Aydogan

2015-04-07

Measuring plant chlorophyll concentration is a well-known and commonly used method in agriculture and environmental applications for monitoring plant health, which also correlates with many other plant parameters including, e.g., carotenoids, nitrogen, maximum green fluorescence, etc. Direct chlorophyll measurement using chemical extraction is destructive, complex and time-consuming, which has led to the development of mobile optical readers, providing non-destructive but at the same time relatively expensive tools for evaluation of plant chlorophyll levels. Here we demonstrate accurate measurement of chlorophyll concentration in plant leaves using Google Glass and a custom-developed software application together with a cost-effective leaf holder and multi-spectral illuminator device. Two images, taken using Google Glass, of a leaf placed in our portable illuminator device under red and white (i.e., broadband) light-emitting-diode (LED) illumination are uploaded to our servers for remote digital processing and chlorophyll quantification, with results returned to the user in less than 10 seconds. Intensity measurements extracted from the uploaded images are mapped against gold-standard colorimetric measurements made through a commercially available reader to generate calibration curves for plant leaf chlorophyll concentration. Using five plant species to calibrate our system, we demonstrate that our approach can accurately and rapidly estimate chlorophyll concentration of fifteen different plant species under both indoor and outdoor lighting conditions. This Google Glass based chlorophyll measurement platform can display the results in spatiotemporal and tabular forms and would be highly useful for monitoring of plant health in environmental and agriculture related applications, including e.g., urban plant monitoring, indirect measurements of the effects of climate change, and as an early indicator for water, soil, and air quality degradation.

A cost-effective smartphone-based antimicrobial susceptibility test reader for drug resistance testing (Conference Presentation)

NASA Astrophysics Data System (ADS)

Feng, Steve W.; Tseng, Derek; Di Carlo, Dino; Garner, Omai B.; Ozcan, Aydogan

2017-03-01

Antimicrobial susceptibility testing (AST) is commonly used for determining microbial drug resistance, but routine testing, which can significantly reduce the spread of multi-drug resistant organisms, is not regularly performed in resource-limited and field-settings due to technological challenges and lack of trained diagnosticians. We developed a portable cost-effective smartphone-based colorimetric 96-well microtiter plate (MTP) reader capable of automated AST without the need for a trained diagnostician. This system is composed of a smartphone used in conjunction with a 3D-printed opto-mechanical attachment, which holds a set of inexpensive light-emitting-diodes and fiber-optic cables coupled to the 96-well MTP for enabling the capture of the transmitted light through each well by the smartphone camera. Images of the MTP plate are captured at multiple exposures and uploaded to a local or remote server (e.g., a laptop) for automated processing/analysis of the results using a custom-designed smartphone application. Each set of images are combined to generate a high dynamic-range image and analyzed for well turbidity (indicative of bacterial growth), followed by interpretative analysis per plate to determine minimum inhibitory concentration (MIC) and drug susceptibility for the specific bacterium. Results are returned to the originating device within 1 minute and shown to the user in tabular form. We demonstrated the capability of this platform using MTPs prepared with 17 antibiotic drugs targeting Gram-negative bacteria and tested 82 patient isolate MTPs of Klebsiella pneumoniae, achieving well turbidity accuracy of 98.19%, MIC accuracy of 95.15%, and drug susceptibility interpretation accuracy of 99.06%, meeting the FDA defined criteria for AST.

Combating WMD Journal. Issue 2

DTIC Science & Technology

2008-03-01

can be conducted utilizing passive detectors such as thermoluminescent dosime- ters (TLDs) or optically stimulated luminescent ( OSL ) dosimeters ...reasonable estimate of the dose. The challenge in high-energy bremsstrahlung fields is that current (standard) dosimeters do not provide for CPE...above a few MeV. CPE can be obtained by placing tissue- equivalent material (such as a build- up cap) around the dosimeter . This Dosimetry Needs

Fluvial terraces of the Little River Valley, Atlantic Coastal Plain, North Carolina

Treesearch

Bradley Suther; David Leigh; George Brook

2011-01-01

An optically-stimulated luminescence (OSL) and radiocarbon chronology is presented for fluvial terraces of the Little River, a tributary to the Cape Fear River that drains 880 km2 of the Sandhills Province of the upper Coastal Plain of North Carolina. This study differs from previous work in the southeastern Atlantic Coastal Plain in that numerical age estimates are...

Constraints on the age of the Great Sand Dunes, Colorado, from subsurface stratigraphy and OSL dates

USGS Publications Warehouse

Madole, Richard F.; Mahan, Shannon; Romig, Joseph H.; Havens, Jeremy C.

2013-01-01

The age of the Great Sand Dunes has been debated for nearly 150 yr. Seven ages ranging from Miocene to late Holocene have been proposed for them. This paper presents new information—chiefly subsurface stratigraphic data, OSL dates, and geomorphic evidence—that indicates that the Great Sand Dunes began to form in the latter part of the middle Pleistocene. The dunes overlie a thick wedge of piedmont-slope deposits, which in turn overlies sediment of Lake Alamosa, a paleolake that began to drain about 440 ka. The wedge of piedmont-slope deposits extends westward for at least 23 km and is as much as 60 m thick at a distance of 10 km from the Sangre de Cristo Range. Ostracodes from one well indicate that the eastern shoreline of Lake Alamosa extended to within 4.3 km of where the Great Sand Dunes eventually formed. The time represented by the wedge of piedmont-slope deposits is not known exactly, but the wedge post-dates 440 ka and was in place prior to 130 ka because by then the dunes overlying it were sufficiently close and tall enough to obstruct streams draining from the Sangre de Cristo Range.

A non-destructive method for dating human remains

USGS Publications Warehouse

Lail, Warren K.; Sammeth, David; Mahan, Shannon; Nevins, Jason

2013-01-01

The skeletal remains of several Native Americans were recovered in an eroded state from a creek bank in northeastern New Mexico. Subsequently stored in a nearby museum, the remains became lost for almost 36 years. In a recent effort to repatriate the remains, it was necessary to fit them into a cultural chronology in order to determine the appropriate tribe(s) for consultation pursuant to the Native American Grave Protection and Repatriation Act (NAGPRA). Because the remains were found in an eroded context with no artifacts or funerary objects, their age was unknown. Having been asked to avoid destructive dating methods such as radiocarbon dating, the authors used Optically Stimulated Luminescence (OSL) to date the sediments embedded in the cranium. The OSL analyses yielded reliable dates between A.D. 1415 and A.D. 1495. Accordingly, we conclude that the remains were interred somewhat earlier than A.D. 1415, but no later than A.D. 1495. We believe the remains are from individuals ancestral to the Ute Mouache Band, which is now being contacted for repatriation efforts. Not only do our methods contribute to the immediate repatriation efforts, they provide archaeologists with a versatile, non-destructive, numerical dating method that can be used in many burial contexts.

Barrier island response to late Holocene climate events, North Carolina, USA

USGS Publications Warehouse

Mallinson, D.J.; Smith, C.W.; Mahan, S.; Culver, S.J.; McDowell, K.

2011-01-01

The Outer Banks barrier islands of North Carolina, USA, contain a geologic record of inlet activity that extends from ca. 2200. cal. yr BP to the present, and can be used as a proxy for storm activity. Optically stimulated luminescence (OSL) dating (26 samples) of inlet-fill and flood tide delta deposits, recognized in cores and geophysical data, provides the basis for understanding the chronology of storm impacts and comparison to other paleoclimate proxy data. OSL ages of historical inlet fill compare favorably to historical documentation of inlet activity, providing confidence in the technique. Comparison suggests that the Medieval Warm Period (MWP) and Little Ice Age (LIA) were both characterized by elevated storm conditions as indicated by much greater inlet activity relative to today. Given present understanding of atmospheric circulation patterns and sea-surface temperatures during the MWP and LIA, we suggest that increased inlet activity during the MWP responded to intensified hurricane impacts, while elevated inlet activity during the LIA was in response to increased nor'easter activity. A general decrease in storminess at mid-latitudes in the North Atlantic over the last 300. yr has allowed the system to evolve into a more continuous barrier with few inlets. ?? 2011 University of Washington.

Quaternary geologic map of the north-central part of the Salinas River Valley and Arroyo Seco, Monterey County, California

USGS Publications Warehouse

Taylor, Emily M.; Sweetkind, Donald S.

2014-01-01

Arroyo Seco, a perennial drainage in the central Coast Range of California, records a sequence of strath terraces. These terraces preserve an erosional and depositional history, controlled by both climate change and regional tectonics. These deposits have been mapped and correlated on the basis of field investigations, digital terrain analysis, stream gradient profiles, evaluation of published regional soil maps, and satellite imagery. Seven of the strath terraces and associated alluvial fans have been dated by optically stimulated luminescence (OSL) or infrared stimulated luminescence (IRSL). The OSL and IRSL dates on seven of the strath terraces and associated alluvial fans in Arroyo Seco are approximately >120 ka, >65 ka, 51–46 ka, 36–35 ka, 9 ka, and 2–1 ka. These dates generally fall within the range of ages reported from many well-dated marine terraces on the California coast that are formed during sea-level high stands. Tectonic movements, consistently upward, result in a constantly and slowly emerging coastline, however, the regional effects of climate change and resulting eustatic sea-level rises are interpreted as the driving mechanism for erosion and aggradation in Arroyo Seco.

Survey of patient dosimetry for head and neck cancer patients undergoing external radiotherapy treatment: a study from northeastern hospitals of India.

PubMed

Sharma, Arunkumar B; Singh, Tomcha Th; Singh, Khelendra N; Gartia, R K

2009-01-01

To study dosimetry of patients during the external radiotherapy of head and neck cancers from different hospitals of the northeastern region (NER) of India. 35 confirmed cases of head and neck cancers reporting to three different hospitals in the NER of India who underwent radiation treatment were the materials for the study. Dosimetry was carried out at 8(eight) anatomical points to these patients, namely, target (entrance and exit points), forehead, chest, abdomen, gonad, arm, and leg respectively by thermoluminescence (TL) as well as optically stimulated luminescence (OSL) dosimeters. Unlike conventional appliances, we used common iodized salt as TL/OSL phosphor. Patient dosimetry was found to vary with an average of 1.17 +/- 0.39 Sv at forehead, 1.24 +/- 0.39 Sv at chest, 0.52 +/- 0.13 Sv at gonad to a minimum of 0.26 +/- 0.07 Sv at leg areas when exposed to a cumulative dose of 65 Sv at the target. Maximum dose received from a stray radiation is about 1.5 Sv at forehead/chest and dosimetry of patient among the three centers is not significantly different at the 5% level of probability.

Optical, scintillation and dosimeter properties of MgO:Tb translucent ceramics synthesized by the SPS method

NASA Astrophysics Data System (ADS)

Kawano, Naoki; Kato, Takumi; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2017-11-01

MgO translucent ceramics doped with different concentrations of Tb (0.01, 0.05, 0.1, 0.5%) were prepared by the Spark Plasma Sintering (SPS) method. Further, the optical, scintillation, dosimeter properties of were evaluated systematically. In the photoluminescence (PL) and scintillation spectra, sharp emission peaks due to the 4f-4f transitions of Tb3+ were observed. In the PL and scintillation decay curves, the decay time constants were a few ms which were on a typical order of the 4f-4f transitions of Tb3+. The thermally-stimulated luminescence (TSL) glow curves exhibited glow peaks around 80, 160 °C after X ray irradiation of 10 mGy. The intensity of TSL peak at 160 °C exhibited a linear response against X-ray dose over a dose range of 0.1-10 mGy. The optically-stimulated luminescence (OSL) under 590 nm stimulation exhibited strong emissions due to Tb3+ around 385-550 nm after X-ray irradiation. As in TSL, the intensity of OSL peak showed a linear response to X-ray dose, and the dynamic range confirmed was 0.1-1000 mGy.

Tests and foreseen developments of fibered-OSLD gamma heating measurements in low-power reactors

NASA Astrophysics Data System (ADS)

Gruel, A.; Guillou, M. Le; Blaise, P.; Destouches, C.; Magne, S.

2018-01-01

In this paper are presented test measurements of a fibered-OSLD system performed during a dedicated experimental phase in EOLE zero-power reactor. The measurement setup consists of an OSLD crystal connected onto the extremity of an optical fiber and a laser stimulation system, manufactured by the CEA/LIST in Saclay. The OSL sensor is remotely stimulated via an optical fiber using a diode-pumped solid-state laser. The OSL light is collected and guided back along the same fiber to a photomultiplier tube. Results obtained using this system are compared to usual gamma heating measurement protocol using OSLD pellets. The presence of induced radio-luminescence in the OSLD during the irradiation was also observed and could be used to monitor the gamma flux. The feasibility of remote measurements is achieved, whereas further developments could be conducted to improve this technique since the readout procedure still requires to withdraw the OSLD off the gamma flux (hence from the core) on account of the dose rate (around a few Gy.h-1), and the readout time remains quite long for on-line applications. Several improvements are foreseen, and will be tested in the forthcoming years.

Late Quaternary environments of the Waco Mammoth site, Texas USA

NASA Astrophysics Data System (ADS)

Nordt, Lee; Bongino, John; Forman, Steven; Esker, Don; Benedict, Anita

2015-11-01

The Waco Mammoth Site (WMS) in central Texas contains the remains of the largest mammoth herd (Mammuthus columbi) in North America that died in a single catastrophic event. Most mammoths at the site died on a gravel bar of the ancient Bosque River adjacent to a collapsing tributary wall. However, the timing and cause of death of the 26 mammoths documented to date are controversial. The objectives of this research are to: describe and interpret the alluvial stratigraphy and infer the cause of death, employ optically stimulated luminescence (OSL) dating to determine the timing of death, and analyze stable C isotopes of pedogenic carbonate to infer local plant communities, dietary habits, and summer temperatures. Dating of quartz from seven sediment samples by OSL places the death event to a weighted mean of 66.8 ± 5.0 ka. The site is coeval with Marine Oxygen Isotope Stage 4, consistent with our reconstructed mean July temperatures 4°C cooler than today based on a buried soil isotopic transfer function. Our buried soil isotopic interpretation of a dominance of C3 plants is contrary to previous studies of mammoth tooth enamel at the site suggesting a dietary preference for warm season grasses (C4).

Timing and origin for sand dunes in the Green River Lowland of Illinois, upper Mississippi River Valley, USA

USGS Publications Warehouse

Miao, X.; Hanson, P.R.; Wang, Hongfang; Young, A.R.

2010-01-01

The recent increase in dune studies in North America has been heavily focused in the Great Plains, while less attention has historically been given to the dune fields east of the Mississippi River. Here we report ages and suggest a potential sediment source for sand dunes in the Green River Lowland, Illinois, which may provide a better understanding of the dynamic interactions between eolian, glacial, lacustrine and fluvial processes that shaped the landscapes of the upper Midwest. Seven coherent optically stimulated luminescence ages (OSL, or optical ages) obtained from four sites suggest that major dune construction in the Green River Lowland occurred within a narrow time window around 17,500 ago. This implies either an enhanced aridity or an episodic increase of sediment supply at 17,500 years ago, or combination of the both. Contrary to previous assertions that dune sand was sourced from the deflation of the underlying outwash sand deposited when the Lake Michigan Lobe retreated from the area, we propose that Green River Lowland dunes sand originated from the Green Bay Lobe through the Rock River. Specifically, sediment supply increased in the Rock River valley during drainage of Glacial Lake Scuppernong, which formed between ???18,000 and 17,000 years ago, when the Green Bay Lobe retreated from its terminal moraine. The lake drained catastrophically through the Rock River valley, providing glacial sediment and water to erode the preexisting sandy sediments. Throughout the remainder of the late Pleistocene, the Laurentide Ice Sheet drained into larger more northerly glacial lakes that in turn drained through other river valleys. Therefore, the dunes in the Green River Lowland formed only during the catastrophic drainage of Glacial Lake Scuppernong, but were stabilized through the remainder of the Pleistocene. This scenario explains the abrupt dune construction around 17,500 years ago, and explains the lack of later dune activity up to the Pleistocene-Holocene transition. OSL and radiocarbon ages also indicate that dunes were reactivated during the early, middle and late Holocene. Some eolian activation occurred within well-defined dry intervals in the upper Midwest, suggesting that increased aridity may have been the primary driver in mobilizing sand. However, many ages do not correspond to drier periods. In contrast to the relative coherency of the Pleistocene OSL ages from multiple study sites, the Holocene OSL ages do not overlap from one site to another, suggesting that increased aridity alone cannot explain the multiple phases of dune reactivation in the Holocene. Therefore, we conclude that the combined effect of localized disturbances and greater aridity acted in concert to increase eolian sand activity in the Holocene. The multiple periods of eolian activity during the Holocene suggest a high potential for future sand activation in the region, and these results are informative for environmental prediction and potential future mitigation.

Chronology of Terra Firme formation in western Amazonia and implications for the diversification of Amazonian biota

NASA Astrophysics Data System (ADS)

Pupim, Fabiano do N.; Sawakushi, André O.; Hartmann, Gelvam A.; Savian, Jairo F.; Kern, Andrea K.; Mineli, Thays D.; Cruz, Francisco W.; Almeida, Renato P.; Grohmann, Carlos H.; Ribas, Camila C.; d'Horta, Fernando M.; Bertassoli, Dailson J.; Marconato, André; Nogueira, Luciana; Lohmann, Lúcia G.

2017-04-01

The shift from a large wetland dominated by avulsive channels and flooded forests to the incised transcontinental Amazon River valley (Várzea) bounded by non-flooded forests (Terra Firme) is suggested as one of the main drivers of diversification of the mega diverse Amazonian Biota. Nonetheless, there is no consensus about the timing of this landscape shift, with the current literature suggesting a period that ranges from the Miocene (11 Ma) and the Late Pleistocene (100 ka). This uncertainty may be due to a lack of absolute ages for the sediments forming Terra Firme forest substrates in western Amazonian lowlands. In Brazil, the Içá Formation represents the uppermost fluvial deposits of Terra Firme forests substrates in western Amazonia. Therefore, a reliable chronology for the last depositional stage of the Içá Formation is key for an improved understanding of the formation of the current Terra Firme-Várzea system. Four sediment profiles were sampled along the margins of the Solimões and Içá rivers for Optically Stimulated Luminescence (OSL) dating, geomagnetic excursions, and palynological analysis. OSL dating was performed in twelve samples using a Single Aliquot Regeneration (SAR) protocol in quartz sand grains. The equivalent doses ranged from 47 to 130 Gy (Central Age Model) and the dose rate values ranged from 0.4 to 2.0 Gy/ka. The resulting sediment burial ages range from 48 to 112 ka. Paleomagnetic data were obtained from samples collected at same profiles sampled for OSL dating and results suggest the presence of Post-Blake geomagnetic excursion ( 100 ka). The age of 100 ka for Post-Blake excursion are adopted for the Geomagnetic Instability Time Scale. Pollen assemblage data show a similarity to a more modern flora and the presence of Alnus clearly points towards Pleistocene deposition as it is unknown before in South America. The combined OSL, paleomagnetism and pollen data is a robust geochronological dataset that indicates Late Pleistocene ages for the last stage of built up of the Terra Firme in a broad region of the western Brazilian Amazonian lowlands. Therefore, the present-day unconformity between Terra Firme and Várzea deposits were formed by fluvial incision during the late Pleistocene and Holocene, which seems to be related with precipitation changes in the South American monsoon system. Our geochronological dataset point to important landscape changes during the late Pleistocene, with expansion of non-flooded Terra Firme and retraction of Várzea floodplain forests. This transition probably had important implications for the development of modern phylogeographical and biogeographical patterns in western Amazonia during the Quaternary. Future efforts will focus on dating drill-core sediment records using cosmogenic nuclides to extend the age range. Financial support: FAPESP 2009/53988-8, 2012/50260-6, 2014/23334-4, 2014/09800-2, 2016/09293-9; 2016/02656-9; CNPq 3009223/2014-8, 307647/2015-3; NSF DEB 1241066 and NASA.

Characteristics of an OSLD in the diagnostic energy range

DOE Office of Scientific and Technical Information (OSTI.GOV)

Al-Senan, Rani M.; Hatab, Mustapha R.

2011-07-15

Purpose: Optically stimulated luminescence (OSL) dosimetry has been recently introduced in radiation therapy as a potential alternative to the thermoluminescent dosimeter (TLD) system. The aim of this study was to investigate the feasibility of using OSL point dosimeters in the energy range used in diagnostic imaging. Methods: NanoDot OSL dosimeters (OSLDs) were used in this study, which started with testing the homogeneity of a new packet of nanoDots. Reproducibility and the effect of optical treatment (bleaching) were then examined, followed by an investigation of the effect of accumulated dose on the OSLD indicated doses. OSLD linearity, angular dependence, and energymore » dependence were also studied. Furthermore, comparison with LiF:Mg,Ti TLD chips using standard CT dose phantoms at 80 and 120 kVp settings was performed. Results: Batch homogeneity showed a coefficient of variation of <5%. Single-irradiation measurements with bleaching after each OSL readout was found to be associated with a 3.3% reproducibility (one standard deviation measured with a 8 mGy test dose), and no systematic change in OSLDs sensitivity could be noted from measurement to measurement. In contrast, the multiple-irradiation readout without bleaching in between measurements was found to be associated with an uncertainty (using a 6 mGy test dose) that systematically increased with accumulated dose, reaching 42% at 82 mGy. Good linearity was shown by nanoDots under general x-ray, CT, and mammography units with an R{sup 2} > 0.99. The angular dependence test showed a drop of approximately 70% in the OSLD response at 90 deg. in mammography (25 kVp). With the general radiography unit, the maximum drop was 40% at 80 kVp and 20% at 120 kVp, and it was only 10% with CT at both 80 and 120 kVp. The energy dependence study showed a range of ion chamber-to-OSLDs ratios between 0.81 and 1.56, at the energies investigated (29-62 keV). A paired t-test for comparing the OSLDs and TLDs showed no significant variation (p > 0.1). Conclusions: OSLDs exhibited good batch homogeneity (<5%) and reproducibility (3.3%), as well as a linear response. In addition, they showed no statistically significant difference with TLDs in CT measurements (p > 0.1). However, high uncertainty (42%) in the dose estimate was found as a result of relatively high accumulated dose. Furthermore, nanoDots showed high angular dependence (up to 70%) in low kVp techniques. Energy dependence of about 60% was found, and correction factors were suggested for the range of energies investigated. Therefore, if angular and energy dependences are taken into consideration and the uncertainty associated with accumulated dose is avoided, OSLDs (nanoDots) can be suitable for use as point dosimeters in diagnostic settings.« less

Development of 3D in Vitro Technology for Medical Applications

PubMed Central

Ou, Keng-Liang; Hosseinkhani, Hossein

2014-01-01

In the past few years, biomaterials technologies together with significant efforts on developing biology have revolutionized the process of engineered materials. Three dimensional (3D) in vitro technology aims to develop set of tools that are simple, inexpensive, portable and robust that could be commercialized and used in various fields of biomedical sciences such as drug discovery, diagnostic tools, and therapeutic approaches in regenerative medicine. The proliferation of cells in the 3D scaffold needs an oxygen and nutrition supply. 3D scaffold materials should provide such an environment for cells living in close proximity. 3D scaffolds that are able to regenerate or restore tissue and/or organs have begun to revolutionize medicine and biomedical science. Scaffolds have been used to support and promote the regeneration of tissues. Different processing techniques have been developed to design and fabricate three dimensional scaffolds for tissue engineering implants. Throughout the chapters we discuss in this review, we inform the reader about the potential applications of different 3D in vitro systems that can be applied for fabricating a wider range of novel biomaterials for use in tissue engineering. PMID:25299693

Recent advances and product enhancements in reflective cholesteric displays

NASA Astrophysics Data System (ADS)

Khan, Asad; Schneider, Tod; Miller, Nick; Marhefka, Duane; Ernst, Todd; Nicholson, Forrest; Doane, Joseph W.

2005-04-01

Bistable reflective cholesteric displays are a liquid crystal display technology developed to fill a market need for very low power displays on a low-cost, high resolution passive matrix. Their unique look, high reflectivity, bistability, and simple structure make them an ideal flat panel display choice for handheld or other portable devices where small lightweight batteries with long lifetimes are important. We discuss recent advances in cholesteric display technology at Kent Displays such as progress towards single layer black and white displays, standard products, lower cost display modules, and various interface options for cholesteric display applications. It will be shown that inclusion of radio frequency (rf) control options and serial peripheral interface (spi) can greatly enhance the cholesteric display module market penetration by enabling quick integration into end devices. Finally, some discussion will be on the progress of the development of flexible reflective cholesteric displays. These flexible displays can dramatically change industrial design methods by enabling curved surfaces with displays integrated in them. Additional discussion in the paper will include applications of various display modes including signs, hand held instrumentation, and the electronic book and reader.

Discharge measurements at gaging stations

USGS Publications Warehouse

Turnipseed, D. Phil; Sauer, Vernon B.

2010-01-01

The techniques and standards for making discharge measurements at streamflow gaging stations are described in this publication. The vertical axis rotating-element current meter, principally the Price current meter, has been traditionally used for most measurements of discharge; however, advancements in acoustic technology have led to important developments in the use of acoustic Doppler current profilers, acoustic Doppler velocimeters, and other emerging technologies for the measurement of discharge. These new instruments, based on acoustic Doppler theory, have the advantage of no moving parts, and in the case of the acoustic Doppler current profiler, quickly and easily provide three-dimensional stream-velocity profile data through much of the vertical water column. For much of the discussion of acoustic Doppler current profiler moving-boat methodology, the reader is referred to U.S. Geological Survey Techniques and Methods 3-A22 (Mueller and Wagner, 2009). Personal digital assistants (PDAs), electronic field notebooks, and other personal computers provide fast and efficient data-collection methods that are more error-free than traditional hand methods. The use of portable weirs and flumes, floats, volumetric tanks, indirect methods, and tracers in measuring discharge are briefly described.

46 CFR 119.458 - Portable fuel systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Portable fuel systems. 119.458 Section 119.458 Shipping... Machinery Requirements § 119.458 Portable fuel systems. (a) Portable fuel systems, including portable tanks and related fuel lines and accessories, are prohibited except where used for portable dewatering pumps...

46 CFR 119.458 - Portable fuel systems.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Portable fuel systems. 119.458 Section 119.458 Shipping... Machinery Requirements § 119.458 Portable fuel systems. (a) Portable fuel systems, including portable tanks and related fuel lines and accessories, are prohibited except where used for portable dewatering pumps...

30 CFR 75.1100-2 - Quantity and location of firefighting equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

...-trip car, or personnel carrier shall be equipped with one portable fire extinguisher. (e) Electrical... loading point is provided with one of the following: (i) Two portable water cars; or (ii) Two portable chemical cars; or (iii) One portable water car or one portable chemical car, and either (a) a portable foam...

30 CFR 75.1100-2 - Quantity and location of firefighting equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

...-trip car, or personnel carrier shall be equipped with one portable fire extinguisher. (e) Electrical... loading point is provided with one of the following: (i) Two portable water cars; or (ii) Two portable chemical cars; or (iii) One portable water car or one portable chemical car, and either (a) a portable foam...

30 CFR 75.1100-2 - Quantity and location of firefighting equipment.

Code of Federal Regulations, 2014 CFR

2014-07-01

...-trip car, or personnel carrier shall be equipped with one portable fire extinguisher. (e) Electrical... loading point is provided with one of the following: (i) Two portable water cars; or (ii) Two portable chemical cars; or (iii) One portable water car or one portable chemical car, and either (a) a portable foam...

30 CFR 75.1100-2 - Quantity and location of firefighting equipment.

Code of Federal Regulations, 2010 CFR

2010-07-01

...-trip car, or personnel carrier shall be equipped with one portable fire extinguisher. (e) Electrical... loading point is provided with one of the following: (i) Two portable water cars; or (ii) Two portable chemical cars; or (iii) One portable water car or one portable chemical car, and either (a) a portable foam...

30 CFR 75.1100-2 - Quantity and location of firefighting equipment.

Code of Federal Regulations, 2011 CFR

2011-07-01

...-trip car, or personnel carrier shall be equipped with one portable fire extinguisher. (e) Electrical... loading point is provided with one of the following: (i) Two portable water cars; or (ii) Two portable chemical cars; or (iii) One portable water car or one portable chemical car, and either (a) a portable foam...

Portable apparatus for separating sample and detecting target analytes

DOEpatents

Renzi, Ronald F.; Wally, Karl; Crocker, Robert W.; Stamps, James F.; Griffiths; Stewart K. ,; Fruetel, Julia A.; Horn, Brent A.; Shokair, Isaac R.; Yee, Daniel D.; VanderNoot, Victoria A.; Wiedenman, Boyd J.; West, Jason A. A.; Ferko, Scott M.

2008-11-18

Portable devices and methods for determining the presence of a target analyte using a portable device are provided. The portable device is preferably hand-held. A sample is injected to the portable device. A microfluidic separation is performed within the portable device and at least one separated component detected by a detection module within the portable device, in embodiments of the invention. A target analyte is identified, based on the separated component, and the presence of the target analyte is indicated on an output interface of the portable device, in accordance with embodiments of the invention.

Operation CASTLE. Radiological Safety

DTIC Science & Technology

1981-04-01

Electronic Section . . . .. 42 5.3 Photodosimetry and Records Section . . . . . . . 43 5.3.1 Film Packet . . . . . . . . . . 43 5.3.2 Dosimeters ...Accuracy of Du Pont Film Packet 559 as a Personnel Dosimeter . . . 61 A.2 Relative Sensitivity of Films Behind Lead Filters . 61 A.3 Variations of...project and Holmes and Narver (H&N) supervisory personnel as radiological- safety monitors. Three schools were conducted: osle at the Nevada Proving

ESR and U-series analyses of faunal material from Cuddie Springs, NSW, Australia: implications for the timing of the extinction of the Australian megafauna

NASA Astrophysics Data System (ADS)

Grün, Rainer; Eggins, Stephen; Aubert, Maxime; Spooner, Nigel; Pike, Alistair W. G.; Müller, Wolfgang

2010-03-01

The timing and cause of late Pleistocene faunal extinctions in Australia are subjects of a debate that has become polarised by two vigorously defended views. One contends that the late Pleistocene extinction was a short event caused by humans colonising the Australian continent, whereas the other promotes a gradual demise of the fauna, over a period of at least 10-20 ka, due to a combination of climatic changes and ecological pressures by humans. Cuddie Springs is central to this debate as it is the only site known in continental Australia where archaeological and megafauna remains co-occur. We have analysed more than 60 bones and teeth from the site by laser ablation ICP-MS to determine U, and Th concentrations and distributions, and those with sufficiently high U concentrations were analysed for U-series isotopes. Twenty-nine teeth were analysed by ESR. These new results, as well as previously published geochronological data, contradict the hypothesis that the clastic sediments of Stratigraphic Unit 6 (SU6) are in primary context with the faunal, archaeological and other materials found in SU6, and that all have ages consistent with the optically stimulated luminescence (OSL) estimates of 30-36 ka. These young OSL results were used to argue for a relatively recent age of the extinct fauna. Our results imply that SU6 is either significantly older than the OSL results, or that a large fraction of the faunal material and the charcoal found in SU6 was derived from older, lateral deposits. Our U and Th laser ablation ICPMS results as well as the REE profiles reported by Trueman et al. [2008. Comparing rates of recystallisation and the potential for preservation of biomolecules from the distribution of trace elements in fossil bones. C.R. Palevol. General Paleontology (Taphonomy and Fossilization) 7, 145-158] contradict the interpretation of previously reported rare earth element compositions of bones, and the argument based thereon for the primary context of faunal material and clastic sediments in SU6 layers.

Late Pleistocene dune activity in the central Great Plains, USA

USGS Publications Warehouse

Mason, J.A.; Swinehart, J.B.; Hanson, P.R.; Loope, D.B.; Goble, R.J.; Miao, X.; Schmeisser, R.L.

2011-01-01

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20-25 ka are interbedded with loess south of the Sand Hills. Several of the large dunes sampled in the Sand Hills clearly contain a substantial core of Late Pleistocene sand; thus, they had developed by the Late Pleistocene and were fully mobile at that time, although substantial sand deposition and extensive longitudinal dune construction occurred during the Holocene. Many of the Late Pleistocene OSL ages fall between 17 and 14 ka, but it is likely that these ages represent only the later part of a longer period of dune construction and migration. At several sites, significant Late Pleistocene or Holocene large-dune migration also probably occurred after the time represented by the Pleistocene OSL ages. Sedimentary structures in Late Pleistocene eolian sand and the forms of large dunes potentially constructed in the Late Pleistocene both indicate sand transport dominated by northerly to westerly winds, consistent with Late Pleistocene loess transport directions. Numerical modeling of the climate of the Last Glacial Maximum has often yielded mean monthly surface winds southwest of the Laurentide Ice Sheet that are consistent with this geologic evidence, despite strengthened anticyclonic circulation over the ice sheet. Mobility of large dunes during the Late Pleistocene on the central Great Plains may have been the result of cold, short growing seasons with relatively low precipitation and low atmospheric CO2 that increased plant moisture stress, limiting the ability of vegetation to stabilize active dune sand. The apparent coexistence of large mobile dunes with boreal forest taxa suggests a Late Pleistocene environment with few modern analogs. ?? 2011 Elsevier Ltd.

SU-E-T-178: Optically Stimulated Luminescence (OSL) Dosimetry: A Study of A-Al2O3:C Assessed by PENELOPE Monte Carlo Simulation.

PubMed

Nicolucci, P; Schuch, F

2012-06-01

To use the Monte Carlo code PENELOPE to study attenuation and tissue equivalence properties of a-Al2O3:C for OSL dosimetry. Mass attenuation coefficients of α-Al2O3 and α-Al2O3:C with carbon percent weight concentrations from 1% to 150% were simulated with PENELOPE Monte Carlo code and compared to mass attenuation coefficients from soft tissue for photon beams ranging from 50kV to 10MV. Also, the attenuation of primary photon beams of 6MV and 10MV and the generation of secondary electrons by α-Al2O3 :C dosimeters positioned on the entrance surface of a water phantom were studied. A difference of up to 90% was found in the mass attenuation coefficient between the pure \\agr;-A12O3 and the material with 150% weight concentration of dopant at 1.5 keV, corresponding to the K-edge photoelectric absorption of aluminum. However for energies above 80 keV the concentration of carbon does not affect the mass attenuation coefficient and the material presents tissue equivalence for the beams studied. The ratio between the mass attenuation coefficients for \\agr-A12O3:C and for soft tissue are less than unit due to the higher density of the \\agr-A12O3 (2.12 g/cm s ) and its tissue equivalence diminishes to lower concentrations of carbon and for lower energies due to the relation of the radiation interaction effects with atomic number. The larger attenuation of the primary photon beams by the dosimeter was 16% at 250 keV and the maximum increase in secondary electrons fluence to the entrance surface of the phantom was found as 91% at 2MeV. The use of the OSL dosimeters in radiation therapy can be optimized by use of PENELOPE Monte Carlo simulation to provide a study of the attenuation and response characteristics of the material. © 2012 American Association of Physicists in Medicine.

The chronostratigraphy of the Haua Fteah cave (Cyrenaica, northeast Libya) - Optical dating of early human occupation during Marine Isotope Stages 4, 5 and 6.

PubMed

Jacobs, Zenobia; Li, Bo; Farr, Lucy; Hill, Evan; Hunt, Chris; Jones, Sacha; Rabett, Ryan; Reynolds, Tim; Roberts, Richard G; Simpson, David; Barker, Graeme

2017-04-01

The paper presents the results of optical dating of potassium-rich feldspar grains obtained from the Haua Fteah cave in Cyrenaica, northeast Libya, focussing on the chronology of the Deep Sounding excavated by Charles McBurney in the 1950s and re-excavated recently. Samples were also collected from a 1.25 m-deep trench (Trench S) excavated during the present project below the basal level of the Deep Sounding. Optically stimulated luminescence (OSL) data sets for multi-grain, single aliquots of quartz for samples from the Middle Trench were previously published. Re-analyses of these OSL data confirm significant variation in the dose saturation levels of the quartz signal, but allow the most robust OSL ages to be determined for comparison with previous age estimates and with those obtained in this study for potassium-rich feldspars from the Deep Sounding. The latter indicate that humans may have started to visit the cave as early as ∼150 ka ago, but that major use of the cave occurred during MIS 5, with the accumulation of the Deep Sounding sediments. Correlations between optical ages and episodes of "Pre-Aurignacian" artefact discard indicate that human use of the cave during MIS 5 was highly intermittent. The earliest phases of human activity appear to have occurred during interstadial conditions (5e and 5c), with a later phase of lithic discard associated with more stadial conditions, possibly MIS 5b. We argue that the "Pre-Aurignacian" assemblage can probably be linked with modern humans, like the succeeding "Levalloiso-Mousterian" assemblage; two modern human mandibles associated with the latter are associated with a modelled age of 73-65 ka. If this attribution is correct, then the new chronology implies that modern humans using "Pre-Aurignacian" technologies were in Cyrenaica as early as modern humans equipped with "Aterian" technologies were in the Maghreb, raising new questions about variability among lithic technologies during the initial phases of modern human dispersals into North Africa. Copyright © 2017 Elsevier Ltd. All rights reserved.

A new luminescence dating chronology for the Rhafas cave site (NE Morocco): Insights into Palaeolithic human cultural change under varying palaeoenvironmental conditions in the Maghreb

NASA Astrophysics Data System (ADS)

Dörschner, Nina; Fitzsimmons, Kathryn E.; Ditchfield, Peter; McLaren, Sue J.; Steele, Teresa E.; Zielhofer, Christoph; McPherron, Shannon P.; Bouzouggar, Abdeljalil; Hublin, Jean-Jacques

2016-04-01

Archaeological sites in northern Africa provide a rich record that is of increasing importance for current debates relating to the origins of modern human behaviour and to Out of Africa human dispersal events. Particular interest is placed on the cultural transition between the North African Middle Stone Age (MSA) and Late Stone Age (LSA), and the need for accurately defined chronologies, however the timing and nature of Palaeolithic human behaviour and dispersal across north-western Africa (the Maghreb) and potential correlation with environmental conditions remain poorly understood. The inland cave site of Rhafas (Morocco) preserves a long stratified sequence providing valuable chronological information about cultural changes in the Maghreb spanning the North African MSA through to the Neolithic. In this study, we apply optically stimulated luminescence (OSL) dating on sand-sized quartz grains to the cave deposits of Rhafas as well as to a section on the terrace in front of the cave entrance. Single grain OSL dating reliably constrains the timing of technocomplexes beyond the limits of radiocarbon by directly dating sediment associated with archaeological traces. We combine OSL dating with multi-proxy geological investigations (XRF, grain size analyses, stable isotopes, thin sections) to investigate site formation processes and reconstruct palaeoenvironmental conditions during human occupation phases at Rhafas. Our results indicate that the occupation of the site started at least in MIS 6 during a phase of relatively arid environmental conditions. Climatic amelioration after c.140 ka is associated with a change in sediment geochemistry at the site, most likely linked to a change in sediment source due to shifting wind directions. Tanged pieces - typical for the classical Aterian technocomplex - start to occur in the archaeological sequence in MIS 5, consistent with previously published chronological data from the Maghreb. From 55 ka, climatic conditions were sufficiently humid for the pedogenic cementation of Rhafas sediments by carbonates, resulting in the formation of a duricrust several centimetres thick. Deposits from the last glacial period are associated with LSA technocomplexes and fall within previously established chronologies from the Maghreb.

Luminescence dating of Holocene dune complexes along the shore of northern France (Picardy)

NASA Astrophysics Data System (ADS)

Lauer, Tobias; Frechen, Manfred; Meurisse-Fort, Murielle; Gosselin, Guillaume; van Vliet-Lanoë, Brigitte

2010-05-01

The Holocene dune and peat complexes along the shore of northern France (Picardy) had already been studied in detail by Meurisse et al. (2005) and Meurisse-Fort (2009). Information about the palaeodevelopment of those dune fields is hence given due to existing 14C data as well as by sedimentological and morphological analyses. Due to the results from radiocarbon dating, different types of aeolian bodies could be correlated along the Picardy coastline and a regional stratigraphic sequence could be established (Meurisse-Fort, 2009). The aim of the ongoing study is to get a higher chronological resolution for the different phases of dune activity in Picardy by luminescence dating what is a powerful tool to determine the time of last sunlight exposure of grains before burial (this information yields important information about dune movement). Samples for OSL dating were taken from dune bodies located in Tardinghen, Hardelot, Saint-Frieux and Saint-Gabriel. For dating, a single aliquot regenerative dose (SAR) protocol (Murray & Wintle 2003) is applied to coarse grained quartz. First tests concerning the signal intensity, the purity of the quartz OSL signal and the bleaching properties showed that quartz OSL dating works well for the dunes of the northern France coastline. The new luminescence ages will help to better unravel the phases of sand dune activity and stabilisation mainly controlled by climate changes and human impact. References: Meurisse, M., Van Vliet-Lanoë, B., Talon, B. & Recourt, P. (2005): Complexes dunaires et tourbeux holocènes du littoral du Nord de la France. - Geoscience, 337 : 675-684. Meurisse-Fort, M. (2009): Enregistrement haute résolution des massifs dunaires ; Manche, mer du Nord et Atlantique - Le rôle des tempêtes. Thèse de Doctorat soutenue en juin 2007, Université de Lille1. Coll. Recherches - Sciences (Sciences de la Terre). EPU-Publibook (ed.), Paris, 310 pp. Murray, A.S. & Wintle, A.G. (2003): The single aliquot regenerative dose protocol: potential for improvements in reliability. - Radiat. Meas., 37: 377-381.