Ultrahigh speed en face OCT capsule for endoscopic imaging

PubMed Central

Liang, Kaicheng; Traverso, Giovanni; Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Wang, Zhao; Potsaid, Benjamin; Giacomelli, Michael; Jayaraman, Vijaysekhar; Barman, Ross; Cable, Alex; Mashimo, Hiroshi; Langer, Robert; Fujimoto, James G.

2015-01-01

Depth resolved and en face OCT visualization in vivo may have important clinical applications in endoscopy. We demonstrate a high speed, two-dimensional (2D) distal scanning capsule with a micromotor for fast rotary scanning and a pneumatic actuator for precision longitudinal scanning. Longitudinal position measurement and image registration were performed by optical tracking of the pneumatic scanner. The 2D scanning device enables high resolution imaging over a small field of view and is suitable for OCT as well as other scanning microscopies. Large field of view imaging for screening or surveillance applications can also be achieved by proximally pulling back or advancing the capsule while scanning the distal high-speed micromotor. Circumferential en face OCT was demonstrated in living swine at 250 Hz frame rate and 1 MHz A-scan rate using a MEMS tunable VCSEL light source at 1300 nm. Cross-sectional and en face OCT views of the upper and lower gastrointestinal tract were generated with precision distal pneumatic longitudinal actuation as well as proximal manual longitudinal actuation. These devices could enable clinical studies either as an adjunct to endoscopy, attached to an endoscope, or as a swallowed tethered capsule for non-endoscopic imaging without sedation. The combination of ultrahigh speed imaging and distal scanning capsule technology could enable both screening and surveillance applications. PMID:25909001

Ultrahigh speed en face OCT capsule for endoscopic imaging.

PubMed

Liang, Kaicheng; Traverso, Giovanni; Lee, Hsiang-Chieh; Ahsen, Osman Oguz; Wang, Zhao; Potsaid, Benjamin; Giacomelli, Michael; Jayaraman, Vijaysekhar; Barman, Ross; Cable, Alex; Mashimo, Hiroshi; Langer, Robert; Fujimoto, James G

2015-04-01

Depth resolved and en face OCT visualization in vivo may have important clinical applications in endoscopy. We demonstrate a high speed, two-dimensional (2D) distal scanning capsule with a micromotor for fast rotary scanning and a pneumatic actuator for precision longitudinal scanning. Longitudinal position measurement and image registration were performed by optical tracking of the pneumatic scanner. The 2D scanning device enables high resolution imaging over a small field of view and is suitable for OCT as well as other scanning microscopies. Large field of view imaging for screening or surveillance applications can also be achieved by proximally pulling back or advancing the capsule while scanning the distal high-speed micromotor. Circumferential en face OCT was demonstrated in living swine at 250 Hz frame rate and 1 MHz A-scan rate using a MEMS tunable VCSEL light source at 1300 nm. Cross-sectional and en face OCT views of the upper and lower gastrointestinal tract were generated with precision distal pneumatic longitudinal actuation as well as proximal manual longitudinal actuation. These devices could enable clinical studies either as an adjunct to endoscopy, attached to an endoscope, or as a swallowed tethered capsule for non-endoscopic imaging without sedation. The combination of ultrahigh speed imaging and distal scanning capsule technology could enable both screening and surveillance applications.

Generation of ultrasound in materials using continuous-wave lasers.

PubMed

Caron, James N; DiComo, Gregory P; Nikitin, Sergei

2012-03-01

Generating and detecting ultrasound is a standard method of nondestructive evaluation of materials. Pulsed lasers are used to generate ultrasound remotely in situations that prohibit the use of contact transducers. The scanning rate is limited by the repetition rates of the pulsed lasers, ranging between 10 and 100 Hz for lasers with sufficient pulse widths and energies. Alternately, a high-power continuous-wave laser can be scanned across the surface, creating an ultrasonic wavefront. Since generation is continuous, the scanning rate can be as much as 4 orders of magnitude higher than with pulsed lasers. This paper introduces the concept, comparing the theoretical scanning speed with generation by pulsed laser. © 2012 Optical Society of America

Vibration compensation for high speed scanning tunneling microscopy

NASA Astrophysics Data System (ADS)

Croft, D.; Devasia, S.

1999-12-01

Low scanning speed is a fundamental limitation of scanning tunneling microscopes (STMs), making real time imaging of surface processes and nanofabrication impractical. The effective scanning bandwidth is currently limited by the smallest resonant vibrational frequency of the piezobased positioning system (i.e., scanner) used in the STM. Due to this limitation, the acquired images are distorted during high speed operations. In practice, the achievable scan rates are much less than 1/10th of the resonant vibrational frequency of the STM scanner. To alleviate the scanning speed limitation, this article describes an inversion-based approach that compensates for the structural vibrations in the scanner and thus, allows STM imaging at high scanning speeds (relative to the smallest resonant vibrational frequency). Experimental results are presented to show the increase in scanning speeds achievable by applying the vibration compensation methods.

Hybrid Dispersion Laser Scanner

PubMed Central

Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

2012-01-01

Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points. PMID:22685627

Hologram generation by horizontal scanning of a high-speed spatial light modulator.

PubMed

Takaki, Yasuhiro; Okada, Naoya

2009-06-10

In order to increase the image size and the viewing zone angle of a hologram, a high-speed spatial light modulator (SLM) is imaged as a vertically long image by an anamorphic imaging system, and this image is scanned horizontally by a galvano scanner. The reduction in horizontal pixel pitch of the SLM provides a wide viewing zone angle. The increased image height and horizontal scanning increased the image size. We demonstrated the generation of a hologram having a 15 degrees horizontal viewing zone angle and an image size of 3.4 inches with a frame rate of 60 Hz using a digital micromirror device with a frame rate of 13.333 kHz as a high-speed SLM.

Ultrafast web inspection with hybrid dispersion laser scanner.

PubMed

Chen, Hongwei; Wang, Chao; Yazaki, Akio; Kim, Chanju; Goda, Keisuke; Jalali, Bahram

2013-06-10

We report an ultrafast web inspector that operates at a 1000 times higher scan rate than conventional methods. This system is based on a hybrid dispersion laser scanner that performs line scans at nearly 100 MHz. Specifically, we demonstrate web inspection with detectable resolution of 48.6 μm/pixel (scan direction) × 23 μm (web flow direction) within a width of view of 6 mm at a record high scan rate of 90.9 MHz. We demonstrate the identification and evaluation of particles on silicon wafers. This method holds great promise for speeding up quality control and hence reducing manufacturing costs.

Obstetric audit: the Bradford way.

PubMed

Lodge, Virginia; Lomas, Karen; Jaworskyj, Suzanne; Thomson, Heidi

2014-08-01

Ultrasound is widely used as a screening tool in obstetrics with the aim of reducing maternal and foetal morbidity. However, to be effective it is recommended that scanning services follow standard protocols based on national guidelines and that scanning practice is audited to ensure consistency. Bradford has a multi-ethnic population with one of the highest rates of birth defects in the UK and it requires an effective foetal anomaly screening service. We implemented a rolling programme of audits of dating scans, foetal anomaly scans and growth scans carried out by sonographers in Bradford. All three categories of scan were audited using measurable parameters based on national guidelines. Following feedback and re-training to address issues identified, re-audits of dating and foetal anomaly scans were carried out. In both cases, sonographers being re-audited had a marked improvement in their practice. Analysis of foetal abnormality detection rates showed that as a department, we were reaching the nationally agreed detection rates for the Fetal Anomaly Screening Programme auditable conditions. Audit has been shown to be a useful and essential process in achieving consistent scanning practices and high quality images and measurements.

Obstetric audit: the Bradford way

PubMed Central

Lomas, Karen; Jaworskyj, Suzanne; Thomson, Heidi

2014-01-01

Ultrasound is widely used as a screening tool in obstetrics with the aim of reducing maternal and foetal morbidity. However, to be effective it is recommended that scanning services follow standard protocols based on national guidelines and that scanning practice is audited to ensure consistency. Bradford has a multi-ethnic population with one of the highest rates of birth defects in the UK and it requires an effective foetal anomaly screening service. We implemented a rolling programme of audits of dating scans, foetal anomaly scans and growth scans carried out by sonographers in Bradford. All three categories of scan were audited using measurable parameters based on national guidelines. Following feedback and re-training to address issues identified, re-audits of dating and foetal anomaly scans were carried out. In both cases, sonographers being re-audited had a marked improvement in their practice. Analysis of foetal abnormality detection rates showed that as a department, we were reaching the nationally agreed detection rates for the Fetal Anomaly Screening Programme auditable conditions. Audit has been shown to be a useful and essential process in achieving consistent scanning practices and high quality images and measurements. PMID:27433213

Flexible solid-state symmetric supercapacitors based on MnO2 nanofilms with high rate capability and long cyclability

NASA Astrophysics Data System (ADS)

Wu, Lingxia; Li, Ruizhi; Guo, Junling; Zhou, Cheng; Zhang, Wenpei; Wang, Chong; Huang, Yu; Li, Yuanyuan; Liu, Jinping

2013-08-01

Flexible solid-state symmetric supercapacitor was fabricated using MnO2 nanofilms growing directly on carbon cloth as the electrodes and PVA/H3PO4 gel as the electrolyte/separator. The device can be operated at a stable cell-voltage up to 1.4 V, obviously larger than that of conventional solid-state symmetric supercapacitors (≤1 V). It exhibited excellent rate capability with a scan rate as high as 20 V s-1 and a long cyclability (˜60000 cycles) even under severe mechanical deformation. The charge storage mechanism at different scan rates was also quantitatively analyzed.

High-speed, random-access fluorescence microscopy: I. High-resolution optical recording with voltage-sensitive dyes and ion indicators.

PubMed

Bullen, A; Patel, S S; Saggau, P

1997-07-01

The design and implementation of a high-speed, random-access, laser-scanning fluorescence microscope configured to record fast physiological signals from small neuronal structures with high spatiotemporal resolution is presented. The laser-scanning capability of this nonimaging microscope is provided by two orthogonal acousto-optic deflectors under computer control. Each scanning point can be randomly accessed and has a positioning time of 3-5 microseconds. Sampling time is also computer-controlled and can be varied to maximize the signal-to-noise ratio. Acquisition rates up to 200k samples/s at 16-bit digitizing resolution are possible. The spatial resolution of this instrument is determined by the minimal spot size at the level of the preparation (i.e., 2-7 microns). Scanning points are selected interactively from a reference image collected with differential interference contrast optics and a video camera. Frame rates up to 5 kHz are easily attainable. Intrinsic variations in laser light intensity and scanning spot brightness are overcome by an on-line signal-processing scheme. Representative records obtained with this instrument by using voltage-sensitive dyes and calcium indicators demonstrate the ability to make fast, high-fidelity measurements of membrane potential and intracellular calcium at high spatial resolution (2 microns) without any temporal averaging.

High-speed, random-access fluorescence microscopy: I. High-resolution optical recording with voltage-sensitive dyes and ion indicators.

PubMed Central

Bullen, A; Patel, S S; Saggau, P

1997-01-01

The design and implementation of a high-speed, random-access, laser-scanning fluorescence microscope configured to record fast physiological signals from small neuronal structures with high spatiotemporal resolution is presented. The laser-scanning capability of this nonimaging microscope is provided by two orthogonal acousto-optic deflectors under computer control. Each scanning point can be randomly accessed and has a positioning time of 3-5 microseconds. Sampling time is also computer-controlled and can be varied to maximize the signal-to-noise ratio. Acquisition rates up to 200k samples/s at 16-bit digitizing resolution are possible. The spatial resolution of this instrument is determined by the minimal spot size at the level of the preparation (i.e., 2-7 microns). Scanning points are selected interactively from a reference image collected with differential interference contrast optics and a video camera. Frame rates up to 5 kHz are easily attainable. Intrinsic variations in laser light intensity and scanning spot brightness are overcome by an on-line signal-processing scheme. Representative records obtained with this instrument by using voltage-sensitive dyes and calcium indicators demonstrate the ability to make fast, high-fidelity measurements of membrane potential and intracellular calcium at high spatial resolution (2 microns) without any temporal averaging. Images FIGURE 6 PMID:9199810

Radioisotope scanning of brain, liver, lung and bone with a note on tumour localizing agents

PubMed Central

Lavender, J. P.

1973-01-01

Radioisotopic scanning of brain, liver, lungs and the skeleton is briefly reviewed with a survey of recent developments of clinical significance. In brain scanning neoplasm detection rates of greater than 90% are claimed. The true figure is probably 70-80%. Autopsy data shows a number of false negatives, particularly with vascular lesions. Attempts to make scanning more specific in differentiating neoplasm from vascular lesions by rapid sequence blood flow studies are reviewed. In liver scanning by means of colloids again high success rate is claimed but small metastases are frequently missed and the false negative scan rate is probably quite high. Lung scanning still has its main place in investigating pulmonary embolic disease. Ventilation studies using Xenon 133 are useful, particularly combined with perfusion studies. The various radiopharmaceuticals for use in bone scanning are reviewed. The appearance of technetium labelled phosphate compounds will probably allow much wider use of total skeletal scanning. Research into tumour localizing agents continues, the most recent and interesting being Gallium citrate and labelled bleomycin. Neither agent is predictable however although Gallium may have a place in Hodgkins disease and bronchogenic neoplasm and both may have a place in the detection of cerebral tumours. ImagesFig. 1Fig. 2Fig. 3p452-bFig. 3bFig. 4Fig. 5Fig. 5bFig. 6Fig. 7Fig. 8Fig. 9Fig. 10Fig. 11Fig. 12Fig. 12c & 12dFig. 13Fig. 13 b,c,dFig. 14Fig. 14bFig. 15Fig. 15bFig. 16Fig. 17Fig. 18 PMID:4602127

A simple way to higher speed atomic force microscopy by retrofitting with a novel high-speed flexure-guided scanner

NASA Astrophysics Data System (ADS)

Ouma Alunda, Bernard; Lee, Yong Joong; Park, Soyeun

2018-06-01

A typical line-scan rate for a commercial atomic force microscope (AFM) is about 1 Hz. At such a rate, more than four minutes of scanning time is required to obtain an image of 256 × 256 pixels. Despite control electronics of most commercial AFMs permit faster scan rates, default piezoelectric X–Y scanners limit the overall speed of the system. This is a direct consequence of manufacturers choosing a large scan range over the maximum operating speed for a X–Y scanner. Although some AFM manufacturers offer reduced-scan area scanners as an option, the speed improvement is not significant because such scanners do not have large enough reduction in the scan range and are mainly targeted to reducing the overall cost of the AFM systems. In this article, we present a simple parallel-kinematic substitute scanner for a commercial atomic force microscope to afford a higher scanning speed with no other hardware or software upgrade to the original system. Although the scan area reduction is unavoidable, our modified commercial XE-70 AFM from Park Systems has achieved a line scan rate of over 50 Hz, more than 10 times faster than the original, unmodified system. Our flexure-guided X–Y scanner can be a simple drop-in replacement option for enhancing the speed of various aging atomic force microscopes.

Cyclic Voltammetric Wave-Shapes for Microdisk Electrodes: Coupled Effects of Solution Resistance, Double-Layer Capacitance, and Finite Electrochemical Kinetics

DTIC Science & Technology

1991-05-01

vaveshapea. While the use of high scan rates enhances the effect of electrode kinetics upon the voltametry , the deleterious coupled influence of pa 20...waveshapes. While the use of high scan rates enhances the effect of electrode kinetics upon the voltametry , the deleterious coupled influence of P...2 1 󈧚 Aoki et al have in- 23 vestigated linear sweep voltammetry at microdisks in the reversible case, and Zoski and co-workers have developed

Dual-source spiral CT with pitch up to 3.2 and 75 ms temporal resolution: image reconstruction and assessment of image quality.

PubMed

Flohr, Thomas G; Leng, Shuai; Yu, Lifeng; Aiimendinger, Thomas; Bruder, Herbert; Petersilka, Martin; Eusemann, Christian D; Stierstorfer, Karl; Schmidt, Bernhard; McCollough, Cynthia H

2009-12-01

To present the theory for image reconstruction of a high-pitch, high-temporal-resolution spiral scan mode for dual-source CT (DSCT) and evaluate its image quality and dose. With the use of two x-ray sources and two data acquisition systems, spiral CT exams having a nominal temporal resolution per image of up to one-quarter of the gantry rotation time can be acquired using pitch values up to 3.2. The scan field of view (SFOV) for this mode, however, is limited to the SFOV of the second detector as a maximum, depending on the pitch. Spatial and low contrast resolution, image uniformity and noise, CT number accuracy and linearity, and radiation dose were assessed using the ACR CT accreditation phantom, a 30 cm diameter cylindrical water phantom or a 32 cm diameter cylindrical PMMA CTDI phantom. Slice sensitivity profiles (SSPs) were measured for different nominal slice thicknesses, and an anthropomorphic phantom was used to assess image artifacts. Results were compared between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2. In addition, image quality and temporal resolution of an ECG-triggered version of the DSCT high-pitch spiral scan mode were evaluated with a moving coronary artery phantom, and radiation dose was assessed in comparison with other existing cardiac scan techniques. No significant differences in quantitative measures of image quality were found between single-source scans at pitch = 1.0 and dual-source scans at pitch = 3.2 for spatial and low contrast resolution, CT number accuracy and linearity, SSPs, image uniformity, and noise. The pitch value (1.6 pitch 3.2) had only a minor impact on radiation dose and image noise when the effective tube current time product (mA s/pitch) was kept constant. However, while not severe, artifacts were found to be more prevalent for the dual-source pitch = 3.2 scan mode when structures varied markedly along the z axis, particularly for head scans. Images of the moving coronary artery phantom acquired with the ECG-triggered high-pitch scan mode were visually free from motion artifacts at heart rates of 60 and 70 bpm. However, image quality started to deteriorate for higher heart rates. At equivalent image quality, the ECG-triggered high-pitch scan mode demonstrated lower radiation dose than other cardiac scan techniques on the same DSCT equipment (25% and 60% dose reduction compared to ECG-triggered sequential step-and-shoot and ECG-gated spiral with x-ray pulsing). A high-pitch (up to pitch = 3.2), high-temporal-resolution (up to 75 ms) dual-source CT scan mode produced equivalent image quality relative to single-source scans using a more typical pitch value (pitch = 1.0). The resultant reduction in the overall acquisition time may offer clinical advantage for cardiovascular, trauma, and pediatric CT applications. In addition, ECG-triggered high-pitch scanning may be useful as an alternative to ECG-triggered sequential scanning for patients with low to moderate heart rates up to 70 bpm, with the potential to scan the heart within one heart beat at reduced radiation dose.

Ultrahigh speed endoscopic optical coherence tomography using micromotor imaging catheter and VCSEL technology.

PubMed

Tsai, Tsung-Han; Potsaid, Benjamin; Tao, Yuankai K; Jayaraman, Vijaysekhar; Jiang, James; Heim, Peter J S; Kraus, Martin F; Zhou, Chao; Hornegger, Joachim; Mashimo, Hiroshi; Cable, Alex E; Fujimoto, James G

2013-07-01

We developed a micromotor based miniature catheter with an outer diameter of 3.2 mm for ultrahigh speed endoscopic swept source optical coherence tomography (OCT) using a vertical cavity surface-emitting laser (VCSEL) at a 1 MHz axial scan rate. The micromotor can rotate a micro-prism at several hundred frames per second with less than 5 V drive voltage to provide fast and stable scanning, which is not sensitive to the bending of the catheter. The side-viewing probe can be pulled back to acquire a three-dimensional (3D) data set covering a large area on the specimen. The VCSEL provides a high axial scan rate to support dense sampling under high frame rate operation. Using a high speed data acquisition system, in vivo 3D-OCT imaging in the rabbit GI tract and ex vivo imaging of a human colon specimen with 8 μm axial resolution, 8 μm lateral resolution and 1.2 mm depth range in tissue at a frame rate of 400 fps was demonstrated.

Ultrahigh speed endoscopic optical coherence tomography using micromotor imaging catheter and VCSEL technology

PubMed Central

Tsai, Tsung-Han; Potsaid, Benjamin; Tao, Yuankai K.; Jayaraman, Vijaysekhar; Jiang, James; Heim, Peter J. S.; Kraus, Martin F.; Zhou, Chao; Hornegger, Joachim; Mashimo, Hiroshi; Cable, Alex E.; Fujimoto, James G.

2013-01-01

We developed a micromotor based miniature catheter with an outer diameter of 3.2 mm for ultrahigh speed endoscopic swept source optical coherence tomography (OCT) using a vertical cavity surface-emitting laser (VCSEL) at a 1 MHz axial scan rate. The micromotor can rotate a micro-prism at several hundred frames per second with less than 5 V drive voltage to provide fast and stable scanning, which is not sensitive to the bending of the catheter. The side-viewing probe can be pulled back to acquire a three-dimensional (3D) data set covering a large area on the specimen. The VCSEL provides a high axial scan rate to support dense sampling under high frame rate operation. Using a high speed data acquisition system, in vivo 3D-OCT imaging in the rabbit GI tract and ex vivo imaging of a human colon specimen with 8 μm axial resolution, 8 μm lateral resolution and 1.2 mm depth range in tissue at a frame rate of 400 fps was demonstrated. PMID:23847737

Optical resolution photoacoustic microscopy using novel high-repetition-rate passively Q-switched microchip and fiber lasers.

PubMed

Shi, Wei; Kerr, Shaun; Utkin, Ilya; Ranasinghesagara, Janaka; Pan, Lei; Godwal, Yogesh; Zemp, Roger J; Fedosejevs, Robert

2010-01-01

Optical-resolution photoacoustic microscopy (OR-PAM) is a novel imaging technology for visualizing optically absorbing superficial structures in vivo with lateral spatial resolution determined by optical focusing rather than acoustic detection. Since scanning of the illumination spot is required, OR-PAM imaging speed is limited by both scanning speed and laser pulse repetition rate. Unfortunately, lasers with high repetition rates and suitable pulse durations and energies are not widely available and can be cost-prohibitive and bulky. We are developing compact, passively Q-switched fiber and microchip laser sources for this application. The properties of these lasers are discussed, and pulse repetition rates up to 100 kHz are demonstrated. OR-PAM imaging was conducted using a previously developed photoacoustic probe, which enabled flexible scanning of the focused output of the lasers. Phantom studies demonstrate the ability to image with lateral spatial resolution of 7±2 μm with the microchip laser system and 15±5 μm with the fiber laser system. We believe that the high pulse repetition rates and the potentially compact and fiber-coupled nature of these lasers will prove important for clinical imaging applications where real-time imaging performance is essential.

High frame-rate en face optical coherence tomography system using KTN optical beam deflector

NASA Astrophysics Data System (ADS)

Ohmi, Masato; Shinya, Yusuke; Imai, Tadayuki; Toyoda, Seiji; Kobayashi, Junya; Sakamoto, Tadashi

2017-02-01

We developed high frame-rate en face optical coherence tomography (OCT) system using KTa1-xNbxO3 (KTN) optical beam deflector. In the imaging system, the fast scanning was performed at 200 kHz by the KTN optical beam deflector, while the slow scanning was performed at 800 Hz by the galvanometer mirror. As a preliminary experiment, we succeeded in obtaining en face OCT images of human fingerprint with a frame rate of 800 fps. This is the highest frame-rate obtained using time-domain (TD) en face OCT imaging. The 3D-OCT image of sweat gland was also obtained by our imaging system.

Feature Tracking for High Speed AFM Imaging of Biopolymers.

PubMed

Hartman, Brett; Andersson, Sean B

2018-03-31

The scanning speed of atomic force microscopes continues to advance with some current commercial microscopes achieving on the order of one frame per second and at least one reaching 10 frames per second. Despite the success of these instruments, even higher frame rates are needed with scan ranges larger than are currently achievable. Moreover, there is a significant installed base of slower instruments that would benefit from algorithmic approaches to increasing their frame rate without requiring significant hardware modifications. In this paper, we present an experimental demonstration of high speed scanning on an existing, non-high speed instrument, through the use of a feedback-based, feature-tracking algorithm that reduces imaging time by focusing on features of interest to reduce the total imaging area. Experiments on both circular and square gratings, as well as silicon steps and DNA strands show a reduction in imaging time by a factor of 3-12 over raster scanning, depending on the parameters chosen.

Electrostatic forward-viewing scanning probe for Doppler optical coherence tomography using a dissipative polymer catheter.

PubMed

Munce, Nigel R; Mariampillai, Adrian; Standish, Beau A; Pop, Mihaela; Anderson, Kevan J; Liu, George Y; Luk, Tim; Courtney, Brian K; Wright, Graham A; Vitkin, I Alex; Yang, Victor X D

2008-04-01

A novel flexible scanning optical probe is constructed with a finely etched optical fiber strung through a platinum coil in the lumen of a dissipative polymer. The packaged probe is 2.2 mm in diameter with a rigid length of 6mm when using a ball lens or 12 mm when scanning the fiber proximal to a gradient-index (GRIN) lens. Driven by constant high voltage (1-3 kV) at low current (< 5 microA), the probe oscillates to provide wide forward-viewing angle (13 degrees and 33 degrees with ball and GRIN lens designs, respectively) and high-frame-rate (10-140 fps) operation. Motion of the probe tip is observed with a high-speed camera and compared with theory. Optical coherence tomography (OCT) imaging with the probe is demonstrated with a wavelength-swept source laser. Images of an IR card as well as in vivo Doppler OCT images of a tadpole heart are presented. This optomechanical design offers a simple, inexpensive method to obtain a high-frame-rate forward-viewing scanning probe.

/sup 75/Se-selenomethionine scintigraphy in mediastinal diseases

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

Masaoka, A.; Kyo, S.

1978-03-01

Chest scanning with /sup 75/Se-selenomethionine was performed in 59 cases of mediastinal diseases. All cases of vascular diseases, cystic tumors, and benign neurogenic tumor were negatively scanned. Parenchymatous teratoma, thymoma, malignant lymphoma, Castleman's tumor, epithelial tumors, tuberculous lymphadenitis, and sarcoidosis showed high positive rates. In myasthenic thymus without thymoma two out of 15 cases were positive. The scan images of the resected specimens and preoperative chest scannings coincided.

New Melting Data of the Two Polymorphs of Prednisolone.

PubMed

Corvis, Yohann; Négrier, Philippe; Soulestin, Jérémie; Espeau, Philippe

2016-10-04

Prednisolone is known to exist in two anhydrous solid polymorphic forms. The substance is known to degrade upon melting, resulting in erroneous melting data, as shown by the widely scattered results reported in the literature. In this article, thermal analyses carried out at different scan rates show that the onset temperature and the enthalpy value of the signal increase with the scan rate and reach plateau values for high scan rates. Owing to flash scanning calorimetry, the plateau value for the temperature has been identified as the "true" temperature of melting of both polymorphs. This consistent set of new thermodynamic data on the two solid forms leads to the conclusion that both forms are unambiguously enantiotropes of each other. The solid-solid transition has been observed experimentally for the first time and has been confirmed by calculation.

Fast scan control for deflection type mass spectrometers

NASA Technical Reports Server (NTRS)

Yeager, P. R.; Gaetano, G.; Hughes, D. B. (Inventor)

1974-01-01

A high speed scan device is reported that allows most any scanning sector mass spectrometer to measure preselected gases at a very high sampling rate. The device generates a rapidly changing staircase output which is applied to the accelerator of the spectrometer and it also generates defocusing pulses that are applied to one of the deflecting plates of the spectrometer which when shorted to ground deflects the ion beam away from the collector. A defocusing pulse occurs each time there is a change in the staircase output.

Near-real-time mosaics from high-resolution side-scan sonar

USGS Publications Warehouse

Danforth, William W.; O'Brien, Thomas F.; Schwab, W.C.

1991-01-01

High-resolution side-scan sonar has proven to be a very effective tool for stuyding and understanding the surficial geology of the seafloor. Since the mid-1970s, the US Geological Survey has used high-resolution side-scan sonar systems for mapping various areas of the continental shelf. However, two problems typically encountered included the short range and the high sampling rate of high-resolution side-scan sonar systems and the acquisition and real-time processing of the enormous volume of sonar data generated by high-resolution suystems. These problems were addressed and overcome in August 1989 when the USGS conducted a side-scan sonar and bottom sampling survey of a 1000-sq-km section of the continental shelf in the Gulf of Farallones located offshore of San Francisco. The primary goal of this survey was to map an area of critical interest for studying continental shelf sediment dynamics. This survey provided an opportunity to test an image processing scheme that enabled production of a side-scan sonar hard-copy mosaic during the cruise in near real-time.

Comparison of myocardial perfusion imaging between the new high-speed gamma camera and the standard anger camera.

PubMed

Tanaka, Hirokazu; Chikamori, Taishiro; Hida, Satoshi; Uchida, Kenji; Igarashi, Yuko; Yokoyama, Tsuyoshi; Takahashi, Masaki; Shiba, Chie; Yoshimura, Mana; Tokuuye, Koichi; Yamashina, Akira

2013-01-01

Cadmium-zinc-telluride (CZT) solid-state detectors have been recently introduced into the field of myocardial perfusion imaging. The aim of this study was to prospectively compare the diagnostic performance of the CZT high-speed gamma camera (Discovery NM 530c) with that of the standard 3-head gamma camera in the same group of patients. The study group consisted of 150 consecutive patients who underwent a 1-day stress-rest (99m)Tc-sestamibi or tetrofosmin imaging protocol. Image acquisition was performed first on a standard gamma camera with a 15-min scan time each for stress and for rest. All scans were immediately repeated on a CZT camera with a 5-min scan time for stress and a 3-min scan time for rest, using list mode. The correlations between the CZT camera and the standard camera for perfusion and function analyses were strong within narrow Bland-Altman limits of agreement. Using list mode analysis, image quality for stress was rated as good or excellent in 97% of the 3-min scans, and in 100% of the ≥4-min scans. For CZT scans at rest, similarly, image quality was rated as good or excellent in 94% of the 1-min scans, and in 100% of the ≥2-min scans. The novel CZT camera provides excellent image quality, which is equivalent to standard myocardial single-photon emission computed tomography, despite a short scan time of less than half of the standard time.

Range imaging pulsed laser sensor with two-dimensional scanning of transmitted beam and scanless receiver using high-aspect avalanche photodiode array for eye-safe wavelength

NASA Astrophysics Data System (ADS)

Tsuji, Hidenobu; Imaki, Masaharu; Kotake, Nobuki; Hirai, Akihito; Nakaji, Masaharu; Kameyama, Shumpei

2017-03-01

We demonstrate a range imaging pulsed laser sensor with two-dimensional scanning of a transmitted beam and a scanless receiver using a high-aspect avalanche photodiode (APD) array for the eye-safe wavelength. The system achieves a high frame rate and long-range imaging with a relatively simple sensor configuration. We developed a high-aspect APD array for the wavelength of 1.5 μm, a receiver integrated circuit, and a range and intensity detector. By combining these devices, we realized 160×120 pixels range imaging with a frame rate of 8 Hz at a distance of about 50 m.

Variations in the intensive use of head CT for elderly patients with hemorrhagic stroke.

PubMed

Bekelis, Kimon; Fisher, Elliott S; Labropoulos, Nicos; Zhou, Weiping; Skinner, Jonathan

2015-04-01

To investigate the variability in head computed tomographic (CT) scanning in patients with hemorrhagic stroke in U.S. hospitals, its association with mortality, and the number of different physicians consulted. The study was approved by the Committee for the Protection of Human Subjects at Dartmouth College. A retrospective analysis of the Medicare fee-for-service claims data was performed for elderly patients admitted for hemorrhagic stroke in 2008-2009, with 1-year follow-up through 2010. Risk-adjusted primary outcome measures were mean number of head CT scans performed and high-intensity use of head CT (six or more head CT scans performed in the year after admission). We examined the association of high-intensity use of head CT with the number of different physicians consulted and mortality. A total of 53 272 patients (mean age, 79.6 years; 31 377 women [58.9%]) with hemorrhagic stroke were identified in the study period. The mean number of head CT scans conducted in the year after admission for stroke was 3.4; 8737 patients (16.4%) underwent six or more scans. Among the hospitals with the highest case volume (more than 50 patients with hemorrhagic stroke), risk-adjusted rates ranged from 8.0% to 48.1%. The correlation coefficient between number of physicians consulted and rates of high-intensity use of head CT was 0.522 (P < .01) for all hospitals and 0.50 (P < .01) for the highest-volume hospitals. No improvement in 1-year mortality was found for patients undergoing six or more head CT scans (odds ratio, 0.84; 95% confidence interval: 0.69, 1.02). High rates of head CT use for patients with hemorrhagic stroke are frequently observed, without an association with decreased mortality. A higher number of physicians consulted was associated with high-intensity use of head CT. © RSNA, 2014 Online supplemental material is available for this article.

Development of a temperature gradient focusing method for in situ extraterrestrial biomarker analysis.

PubMed

Danger, Grégoire; Ross, David

2008-08-01

Scanning temperature gradient focusing (TGF) is a recently described technique for the simultaneous concentration and separation of charged analytes. It allows for high analyte peak capacities and low LODs in microcolumn electrophoretic separations. In this paper, we present the application of scanning TGF for chiral separations of amino acids. Using a mixture of seven carboxyfluorescein succinimidyl ester-labeled amino acids (including five chiral amino acids) which constitute the Mars7 standard, we show that scanning TGF is a very simple and efficient method for chiral separations. The modulation of TGF separation parameters (temperature window, pressure scan rate, temperature range, and chiral selector concentration) allows optimization of peak efficiencies and analyte resolutions. The use of hydroxypropyl-beta-CD at low concentration (1-5 mmol/L) as a chiral selector, with an appropriate pressure scan rate ( -0.25 Pa/s) and with a low temperature range (3-25 degrees C over 1 cm) provided high resolution between enantiomers (Rs >1.5 for each pair of enantiomers) using a short, 4 cm long capillary. With these new results, the scanning TGF method appears to be a viable method for in situ trace biomarker analysis for future missions to Mars or other solar system bodies.

Applications of high pressure differential scanning calorimetry to aviation fuel thermal stability research

NASA Technical Reports Server (NTRS)

Neveu, M. C.; Stocker, D. P.

1985-01-01

High pressure differential scanning calorimetry (DSC) was studied as an alternate method for performing high temperature fuel thermal stability research. The DSC was used to measure the heat of reaction versus temperature of a fuel sample heated at a programmed rate in an oxygen pressurized cell. Pure hydrocarbons and model fuels were studied using typical DSC operating conditions of 600 psig of oxygen and a temperature range from ambient to 500 C. The DSC oxidation onset temperature was determined and was used to rate the fuels on thermal stability. Kinetic rate constants were determined for the global initial oxidation reaction. Fuel deposit formation is measured, and the high temperature volatility of some tetralin deposits is studied by thermogravimetric analysis. Gas chromatography and mass spectrometry are used to study the chemical composition of some DSC stressed fuels.

CVD-graphene for low equivalent series resistance in rGO/CVD-graphene/Ni-based supercapacitors.

PubMed

Kwon, Young Hwi; Kumar, Sunil; Bae, Joonho; Seo, Yongho

2018-05-11

Reduced equivalent series resistance (ESR) is necessary, particularly at a high current density, for high performance supercapacitors, and the interface resistance between the current collector and electrode material is one of the main components of ESR. In this report, we have optimized chemical vapor deposition-grown graphene (CVD-G) on a current collector (Ni-foil) using reduced graphene oxide as an active electrode material to fabricate an electric double layer capacitor with reduced ESR. The CVD-G was grown at different cooling rates-20 °C min -1 , 40 °C min -1 and 100 °C min -1 -to determine the optimum conditions. The lowest ESR, 0.38 Ω, was obtained for a cell with a 100 °C min -1 cooling rate, while the sample without a CVD-G interlayer exhibited 0.80 Ω. The CVD-G interlayer-based supercapacitors exhibited fast CD characteristics with high scan rates up to 10 Vs -1 due to low ESR. The specific capacitances deposited with CVD-G were in the range of 145.6 F g -1 -213.8 F g -1 at a voltage scan rate of 0.05 V s -1 . A quasi-rectangular behavior was observed in the cyclic voltammetry curves, even at very high scan rates of 50 and 100 V s -1 , for the cell with optimized CVD-G at higher cooling rates, i.e. 100 °C min -1 .

An improved scan laser with a VO2 programmable mirror

NASA Astrophysics Data System (ADS)

Chivian, J. S.; Scott, M. W.; Case, W. E.; Krasutsky, N. J.

1985-04-01

A 10.6-microns scan laser has been constructed and operated with an off-axis cathode ray tube, high reflectance multilayer thin-film structures, and a tapered plasma discharge tube. Equations are given for the switching time of a high-reflectance spot on the VO2 and for the relation of scan laser output power to cavity geometry, cavity losses, and the gain of the active CO2 medium. A scan capability of 2100 easily resolvable directions was demonstrated, and sequential and randomly addressed spot rates of 100,000/sec were achieved. The equations relating output power and cavity mode size were experimentally verified using a nonscanned beam.

Time-optimized laser micro machining by using a new high dynamic and high precision galvo scanner

NASA Astrophysics Data System (ADS)

Jaeggi, Beat; Neuenschwander, Beat; Zimmermann, Markus; Zecherle, Markus; Boeckler, Ernst W.

2016-03-01

High accuracy, quality and throughput are key factors in laser micro machining. To obtain these goals the ablation process, the machining strategy and the scanning device have to be optimized. The precision is influenced by the accuracy of the galvo scanner and can further be enhanced by synchronizing the movement of the mirrors with the laser pulse train. To maintain a high machining quality i.e. minimum surface roughness, the pulse-to-pulse distance has also to be optimized. Highest ablation efficiency is obtained by choosing the proper laser peak fluence together with highest specific removal rate. The throughput can now be enhanced by simultaneously increasing the average power, the repetition rate as well as the scanning speed to preserve the fluence and the pulse-to-pulse distance. Therefore a high scanning speed is of essential importance. To guarantee the required excellent accuracy even at high scanning speeds a new interferometry based encoder technology was used, that provides a high quality signal for closed-loop control of the galvo scanner position. Low inertia encoder design enables a very dynamic scanner system, which can be driven to very high line speeds by a specially adapted control solution. We will present results with marking speeds up to 25 m/s using a f = 100 mm objective obtained with a new scanning system and scanner tuning maintaining a precision of about 5 μm. Further it will be shown that, especially for short line lengths, the machining time can be minimized by choosing the proper speed which has not to be the maximum one.

Memory Scanning, Introversion-Extraversion, and Levels of Processing.

ERIC Educational Resources Information Center

Eysenck, Michael W.; Eysenck, M. Christine

1979-01-01

Investigated was the hypothesis that high arousal increases processing of physical characteristics and reduces processing of semantic characteristics. While introverts and extroverts had equivalent scanning rates for physical features, introverts were significantly slower in searching for semantic features of category membership, indicating…

Multi-MHz retinal OCT.

PubMed

Klein, Thomas; Wieser, Wolfgang; Reznicek, Lukas; Neubauer, Aljoscha; Kampik, Anselm; Huber, Robert

2013-01-01

We analyze the benefits and problems of in vivo optical coherence tomography (OCT) imaging of the human retina at A-scan rates in excess of 1 MHz, using a 1050 nm Fourier-domain mode-locked (FDML) laser. Different scanning strategies enabled by MHz OCT line rates are investigated, and a simple multi-volume data processing approach is presented. In-vivo OCT of the human ocular fundus is performed at different axial scan rates of up to 6.7 MHz. High quality non-mydriatic retinal imaging over an ultra-wide field is achieved by a combination of several key improvements compared to previous setups. For the FDML laser, long coherence lengths and 72 nm wavelength tuning range are achieved using a chirped fiber Bragg grating in a laser cavity at 419.1 kHz fundamental tuning rate. Very large data sets can be acquired with sustained data transfer from the data acquisition card to host computer memory, enabling high-quality averaging of many frames and of multiple aligned data sets. Three imaging modes are investigated: Alignment and averaging of 24 data sets at 1.68 MHz axial line rate, ultra-dense transverse sampling at 3.35 MHz line rate, and dual-beam imaging with two laser spots on the retina at an effective line rate of 6.7 MHz.

Multi-MHz retinal OCT

PubMed Central

Klein, Thomas; Wieser, Wolfgang; Reznicek, Lukas; Neubauer, Aljoscha; Kampik, Anselm; Huber, Robert

2013-01-01

We analyze the benefits and problems of in vivo optical coherence tomography (OCT) imaging of the human retina at A-scan rates in excess of 1 MHz, using a 1050 nm Fourier-domain mode-locked (FDML) laser. Different scanning strategies enabled by MHz OCT line rates are investigated, and a simple multi-volume data processing approach is presented. In-vivo OCT of the human ocular fundus is performed at different axial scan rates of up to 6.7 MHz. High quality non-mydriatic retinal imaging over an ultra-wide field is achieved by a combination of several key improvements compared to previous setups. For the FDML laser, long coherence lengths and 72 nm wavelength tuning range are achieved using a chirped fiber Bragg grating in a laser cavity at 419.1 kHz fundamental tuning rate. Very large data sets can be acquired with sustained data transfer from the data acquisition card to host computer memory, enabling high-quality averaging of many frames and of multiple aligned data sets. Three imaging modes are investigated: Alignment and averaging of 24 data sets at 1.68 MHz axial line rate, ultra-dense transverse sampling at 3.35 MHz line rate, and dual-beam imaging with two laser spots on the retina at an effective line rate of 6.7 MHz. PMID:24156052

Multidimensional Cyclic Voltammetry Simulations of Pseudocapacitive Electrodes with a Conducting Nanorod Scaffold

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

Mei, Bing-Ang; Li, Bin; Lin, Jie

This paper aims to understand the effect of nanoarchitecture on the performance of pseudocapacitive electrodes consisting of conducting scaffold coated with pseudocapacitive material. To do so, two-dimensional numerical simulations of ordered conducting nanorods coated with a thin film of pseudocapacitive material were performed. The simulations reproduced three-electrode cyclic voltammetry measurements based on a continuum model derived from first principles. Two empirical approaches commonly used experimentally to characterize the contributions of surface-controlled and diffusion-controlled charge storage mechanisms to the total current density with respect to scan rate were theoretically validated for the first time. Moreover, the areal capacitive capacitance, attributed tomore » EDL formation, remained constant and independent of electrode dimensions, at low scan rates. However, at high scan rates, it decreased with decreasing conducting nanorod radius and increasing pseudocapacitive layer thickness due to resistive losses. By contrast, the gravimetric faradaic capacitance, due to reversible faradaic reactions, decreased continuously with increasing scan rate and pseudocapacitive layer thickness but was independent of conducting nanorod radius. Note that the total gravimetric capacitance predicted numerically featured values comparable to experimental measurements. Finally, an optimum pseudocapacitive layer thickness that maximizes total areal capacitance was identified as a function of scan rate and confirmed by scaling analysis.« less

Multidimensional Cyclic Voltammetry Simulations of Pseudocapacitive Electrodes with a Conducting Nanorod Scaffold

DOE PAGES

Mei, Bing-Ang; Li, Bin; Lin, Jie; ...

2017-10-27

This paper aims to understand the effect of nanoarchitecture on the performance of pseudocapacitive electrodes consisting of conducting scaffold coated with pseudocapacitive material. To do so, two-dimensional numerical simulations of ordered conducting nanorods coated with a thin film of pseudocapacitive material were performed. The simulations reproduced three-electrode cyclic voltammetry measurements based on a continuum model derived from first principles. Two empirical approaches commonly used experimentally to characterize the contributions of surface-controlled and diffusion-controlled charge storage mechanisms to the total current density with respect to scan rate were theoretically validated for the first time. Moreover, the areal capacitive capacitance, attributed tomore » EDL formation, remained constant and independent of electrode dimensions, at low scan rates. However, at high scan rates, it decreased with decreasing conducting nanorod radius and increasing pseudocapacitive layer thickness due to resistive losses. By contrast, the gravimetric faradaic capacitance, due to reversible faradaic reactions, decreased continuously with increasing scan rate and pseudocapacitive layer thickness but was independent of conducting nanorod radius. Note that the total gravimetric capacitance predicted numerically featured values comparable to experimental measurements. Finally, an optimum pseudocapacitive layer thickness that maximizes total areal capacitance was identified as a function of scan rate and confirmed by scaling analysis.« less

Helicopter pilot scan techniques during low-altitude high-speed flight.

PubMed

Kirby, Christopher E; Kennedy, Quinn; Yang, Ji Hyun

2014-07-01

This study examined pilots' visual scan patterns during a simulated high-speed, low-level flight and how their scan rates related to flight performance. As helicopters become faster and more agile, pilots are expected to navigate at low altitudes while traveling at high speeds. A pilot's ability to interpret information from a combination of visual sources determines not only mission success, but also aircraft and crew survival. In a fixed-base helicopter simulator modeled after the U.S. Navy's MH-60S, 17 active-duty Navy helicopter pilots with varying total flight times flew and navigated through a simulated southern Californian desert course. Pilots' scan rate and fixation locations were monitored using an eye-tracking system while they flew through the course. Flight parameters, including altitude, were recorded using the simulator's recording system. Experienced pilots with more than 1000 total flight hours better maintained a constant altitude (mean altitude deviation = 48.52 ft, SD = 31.78) than less experienced pilots (mean altitude deviation = 73.03 ft, SD = 10.61) and differed in some aspects of their visual scans. They spent more time looking at the instrument display and less time looking out the window (OTW) than less experienced pilots. Looking OTW was associated with less consistency in maintaining altitude. Results may aid training effectiveness specific to helicopter aviation, particularly in high-speed low-level flight conditions.

Clinicians' perceptions of the value of ventilation-perfusion scans.

PubMed

Siegel, Alan; Holtzman, Stephen R; Bettmann, Michael A; Black, William C

2004-07-01

The goal of this investigation was to understand clinicians' perceptions of the probability of pulmonary embolism as a function of V/Q scan results of normal, low, intermediate, and high probability. A questionnaire was developed and distributed to 429 clinicians at a single academic medical center. The response rate was 44% (188 of 429). The questions included level of training, specialty, probability of PE given 1 of the 4 V/Q scan results, and estimations of the charges for V/Q scanning and pulmonary angiography, and estimations of the risks of pulmonary angiography. The medians and ranges for the probability of pulmonary embolism given a normal, low, intermediate, and high probability V/Q scan result were 2.5% (0-30), 12.5% (0.5-52.5), 41.25% (5-75), and 85% (5-100), respectively. Eleven percent (21 of 188) of the respondents listed the probability of PE in patients with a low probability V/Q scan as being 5% or less, and 33% (62 of 188) listed the probability of PE given an intermediate probability scan as 50% or greater. The majority correctly identified the rate of serious complications of pulmonary arteriography, but many respondents underestimated the charge for V/Q scans and pulmonary arteriography. A substantial minority of clinicians do not understand the probability of pulmonary embolism in patients with low and intermediate probability ventilation-perfusion scans. More quantitative reporting of results is recommended. This could be particularly important because VQ scans are used less frequently but are still needed in certain clinical situations.

Dynamic Charge Storage in Ionic Liquids-Filled Nanopores: Insight from a Computational Cyclic Voltammetry Study.

PubMed

He, Yadong; Huang, Jingsong; Sumpter, Bobby G; Kornyshev, Alexei A; Qiao, Rui

2015-01-02

Understanding the dynamic charge storage in nanoporous electrodes with room-temperature ionic liquid electrolytes is essential for optimizing them to achieve supercapacitors with high energy and power densities. Herein, we report coarse-grained molecular dynamics simulations of the cyclic voltammetry of supercapacitors featuring subnanometer pores and model ionic liquids. We show that the cyclic charging and discharging of nanopores are governed by the interplay between the external field-driven ion transport and the sloshing dynamics of ions inside of the pore. The ion occupancy along the pore length depends strongly on the scan rate and varies cyclically during charging/discharging. Unlike that at equilibrium conditions or low scan rates, charge storage at high scan rates is dominated by counterions while the contribution by co-ions is marginal or negative. These observations help explain the perm-selective charge storage observed experimentally. We clarify the mechanisms underlying these dynamic phenomena and quantify their effects on the efficiency of the dynamic charge storage in nanopores.

Relative risk estimates from spatial and space-time scan statistics: Are they biased?

PubMed Central

Prates, Marcos O.; Kulldorff, Martin; Assunção, Renato M.

2014-01-01

The purely spatial and space-time scan statistics have been successfully used by many scientists to detect and evaluate geographical disease clusters. Although the scan statistic has high power in correctly identifying a cluster, no study has considered the estimates of the cluster relative risk in the detected cluster. In this paper we evaluate whether there is any bias on these estimated relative risks. Intuitively, one may expect that the estimated relative risks has upward bias, since the scan statistic cherry picks high rate areas to include in the cluster. We show that this intuition is correct for clusters with low statistical power, but with medium to high power the bias becomes negligible. The same behaviour is not observed for the prospective space-time scan statistic, where there is an increasing conservative downward bias of the relative risk as the power to detect the cluster increases. PMID:24639031

Safe discharge and outpatient investigation of ureteric colic: a retrospective analysis.

PubMed

Stewart, Michael

2017-07-12

Computed tomography of the kidneys, ureters and bladder is the recommended imaging modality for suspected urolithiasis. Early scanning is advised in guidelines, but there is limited published evidence to support this recommendation. In a retrospective study, we reviewed patients managed according to a local guideline. Patients without high-risk features were either imaged during their initial visit (if in the daytime) or discharged for outpatient scans. Complications, unplanned returns, final diagnosis, and intervention rates were compared between groups. Fifty-four patients were scanned during their initial visit and 151 were scanned as an outpatient at a median interval of 10 days. Unplanned return rates were lower in those scanned as outpatients (7.3 vs. 24.1%), with no significant difference in complications (2.0 vs. 3.7%; none leading to permanent harm). Those scanned as outpatients were less likely to have a stone proven by imaging (39.7 vs. 64.8%), but did not have a significantly higher rate of proven alternative diagnosis (9.3 vs. 13.0%). There is no evidence in this cohort that discharging patients for outpatient imaging is associated with poorer outcomes, provided that an appropriate clinical risk assessment is carried out.

CVD-graphene for low equivalent series resistance in rGO/CVD-graphene/Ni-based supercapacitors

NASA Astrophysics Data System (ADS)

Kwon, Young Hwi; Kumar, Sunil; Bae, Joonho; Seo, Yongho

2018-05-01

Reduced equivalent series resistance (ESR) is necessary, particularly at a high current density, for high performance supercapacitors, and the interface resistance between the current collector and electrode material is one of the main components of ESR. In this report, we have optimized chemical vapor deposition-grown graphene (CVD-G) on a current collector (Ni-foil) using reduced graphene oxide as an active electrode material to fabricate an electric double layer capacitor with reduced ESR. The CVD-G was grown at different cooling rates—20 °C min‑1, 40 °C min‑1 and 100 °C min‑1—to determine the optimum conditions. The lowest ESR, 0.38 Ω, was obtained for a cell with a 100 °C min‑1 cooling rate, while the sample without a CVD-G interlayer exhibited 0.80 Ω. The CVD-G interlayer-based supercapacitors exhibited fast CD characteristics with high scan rates up to 10 Vs‑1 due to low ESR. The specific capacitances deposited with CVD-G were in the range of 145.6 F g‑1–213.8 F g‑1 at a voltage scan rate of 0.05 V s‑1. A quasi-rectangular behavior was observed in the cyclic voltammetry curves, even at very high scan rates of 50 and 100 V s‑1, for the cell with optimized CVD-G at higher cooling rates, i.e. 100 °C min‑1.

High energy density supercapacitors from lignin derived submicron activated carbon fibers in aqueous electrolytes

NASA Astrophysics Data System (ADS)

Hu, Sixiao; Zhang, Sanliang; Pan, Ning; Hsieh, You-Lo

2014-12-01

Highly porous submicron activated carbon fibers (ACFs) were robustly generated from low sulfonated alkali lignin and fabricated into supercapacitors for capacitive energy storage. The hydrophilic and high specific surface ACFs exhibited large-size nanographites and good electrical conductivity to demonstrate outstanding electrochemical performance. ACFs from KOH activation, in particular, showed very high 344 F g-1 specific capacitance at low 1.8 mg cm-2 mass loading and 10 mV s-1 scan rate in aqueous electrolytes. Even at relatively high scan rate of 50 mV s-1 and mass loading of 10 mg cm-2, a decent specific capacitance of 196 F g-1 and a remarkable areal capacitance of 0.55 F cm-2 was obtained, leading to high energy density of 8.1 Wh kg-1 based on averaged electrodes mass. Furthermore, over 96% capacitance retention rates were achieved after 5000 charge/discharge cycles. Such excellent performance demonstrated great potential of lignin derived carbons for electrical energy storage.

Comparison of Agar Dilution, Disk Diffusion, MicroScan, and Vitek Antimicrobial Susceptibility Testing Methods to Broth Microdilution for Detection of Fluoroquinolone-Resistant Isolates of the Family Enterobacteriaceae

PubMed Central

Steward, Christine D.; Stocker, Sheila A.; Swenson, Jana M.; O’Hara, Caroline M.; Edwards, Jonathan R.; Gaynes, Robert P.; McGowan, John E.; Tenover, Fred C.

1999-01-01

Fluoroquinolone resistance appears to be increasing in many species of bacteria, particularly in those causing nosocomial infections. However, the accuracy of some antimicrobial susceptibility testing methods for detecting fluoroquinolone resistance remains uncertain. Therefore, we compared the accuracy of the results of agar dilution, disk diffusion, MicroScan Walk Away Neg Combo 15 conventional panels, and Vitek GNS-F7 cards to the accuracy of the results of the broth microdilution reference method for detection of ciprofloxacin and ofloxacin resistance in 195 clinical isolates of the family Enterobacteriaceae collected from six U.S. hospitals for a national surveillance project (Project ICARE [Intensive Care Antimicrobial Resistance Epidemiology]). For ciprofloxacin, very major error rates were 0% (disk diffusion and MicroScan), 0.9% (agar dilution), and 2.7% (Vitek), while major error rates ranged from 0% (agar dilution) to 3.7% (MicroScan and Vitek). Minor error rates ranged from 12.3% (agar dilution) to 20.5% (MicroScan). For ofloxacin, no very major errors were observed, and major errors were noted only with MicroScan (3.7% major error rate). Minor error rates ranged from 8.2% (agar dilution) to 18.5% (Vitek). Minor errors for all methods were substantially reduced when results with MICs within ±1 dilution of the broth microdilution reference MIC were excluded from analysis. However, the high number of minor errors by all test systems remains a concern. PMID:9986809

Can low-resolution airborne laser scanning data be used to model stream rating curves?

USGS Publications Warehouse

Lyon, Steve; Nathanson, Marcus; Lam, Norris; Dahlke, Helen; Rutzinger, Martin; Kean, Jason W.; Laudon, Hjalmar

2015-01-01

This pilot study explores the potential of using low-resolution (0.2 points/m2) airborne laser scanning (ALS)-derived elevation data to model stream rating curves. Rating curves, which allow the functional translation of stream water depth into discharge, making them integral to water resource monitoring efforts, were modeled using a physics-based approach that captures basic geometric measurements to establish flow resistance due to implicit channel roughness. We tested synthetically thinned high-resolution (more than 2 points/m2) ALS data as a proxy for low-resolution data at a point density equivalent to that obtained within most national-scale ALS strategies. Our results show that the errors incurred due to the effect of low-resolution versus high-resolution ALS data were less than those due to flow measurement and empirical rating curve fitting uncertainties. As such, although there likely are scale and technical limitations to consider, it is theoretically possible to generate rating curves in a river network from ALS data of the resolution anticipated within national-scale ALS schemes (at least for rivers with relatively simple geometries). This is promising, since generating rating curves from ALS scans would greatly enhance our ability to monitor streamflow by simplifying the overall effort required.

Some Processing and Dynamic-Range Issues in Side-Scan Sonar Work

NASA Astrophysics Data System (ADS)

Asper, V. L.; Caruthers, J. W.

2007-05-01

Often side-scan sonar data are collected in such a way that they afford little opportunity to do more than simply display them as images. These images are often limited in dynamic range and stored only in an 8-bit tiff format of numbers representing less than true intensity values. Furthermore, there is little prior knowledge during a survey of the best range in which to set those eight bits. This can result in clipped strong targets and/or the depth of shadows so that the bits that can be recovered from the image are not fully representative of target or bottom backscatter strengths. Several top-of-the-line sonars do have a means of logging high-bit-rate digital data (sometimes only as an option), but only dedicated specialists pay much attention to such data, if they record them at all. Most users of side-scan sonars are interested only in the images. Discussed in this paper are issues related to storing and processing of high-bit-rate digital data to preserve their integrity for future enhanced, after- the-fact use and ability to recover actual backscatter strengths. This papers discusses issues in the use high-bit- rate, digital side-scan sonar data. This work was supported by the Office of Naval Research, Code 321OA, and the Naval Oceanographic Office, Mine Warfare Program.

Application of a color scanner for 60Co high dose rate brachytherapy dosimetry with EBT radiochromic film

PubMed Central

Ghorbani, Mahdi; Toossi, Mohammad Taghi Bahreyni; Mowlavi, Ali Asghar; Roodi, Shahram Bayani; Meigooni, Ali Soleimani

2012-01-01

Background. The aim of this study is to evaluate the performance of a color scanner as a radiochromic film reader in two dimensional dosimetry around a high dose rate brachytherapy source. Materials and methods A Microtek ScanMaker 1000XL film scanner was utilized for the measurement of dose distribution around a high dose rate GZP6 60Co brachytherapy source with GafChromic® EBT radiochromic films. In these investigations, the non-uniformity of the film and scanner response, combined, as well as the films sensitivity to scanner’s light source was evaluated using multiple samples of films, prior to the source dosimetry. The results of these measurements were compared with the Monte Carlo simulated data using MCNPX code. In addition, isodose curves acquired by radiochromic films and Monte Carlo simulation were compared with those provided by the GZP6 treatment planning system. Results Scanning of samples of uniformly irradiated films demonstrated approximately 2.85% and 4.97% nonuniformity of the response, respectively in the longitudinal and transverse directions of the film. Our findings have also indicated that the film response is not affected by the exposure to the scanner’s light source, particularly in multiple scanning of film. The results of radiochromic film measurements are in good agreement with the Monte Carlo calculations (4%) and the corresponding dose values presented by the GZP6 treatment planning system (5%). Conclusions The results of these investigations indicate that the Microtek ScanMaker 1000XL color scanner in conjunction with GafChromic EBT film is a reliable system for dosimetric evaluation of a high dose rate brachytherapy source. PMID:23411947

Sestamibi scan-directed parathyroid surgery: potentially high failure rate without measurement of intraoperative parathyroid hormone.

PubMed

Westerdahl, Johan; Bergenfelz, Anders

2004-11-01

The present study evaluated sestamibi scan-directed parathyroidectomy with intraoperative parathyroid hormone (PTH) assessment (ioPTH). The preoperative sestamibi scintigraphies were compared with the intraoperative findings for 103 patients undergoing first exploration for sporadic primary hyperparathyroidism (pHPT). Data were collected prospectively. Ninety-nine patients (96%) were cured. Patients with persistent pHPT (n = 4) all had an incorrect scintigram as well as an insufficient decline of ioPTH. At operation, 90 patients (87%) had solitary parathyroid adenoma; 12 patients had multiglandular disease. In one patient no enlarged parathyroid gland was found. Overall 77 of 118 abnormal glands (65%) were correctly identified by sestamibi scintigraphy. The sensitivity for localizing a single parathyroid adenoma was 80%. Patients with incorrect scintigrams had a higher proportion of upper pole adenomas than patients with correct scans. High glandular weight and high level of serum PTH were important factors for detectability. Sestamibi scintigraphy did not predict multiglandular disease. However, the use of ioPTH identified 8 of the 9 patients with a positive scan (a solitary focus) and multiglandular disease. In contrast, false-negative ioPTH led to four unnecessary bilateral explorations in the 63 patients with a scan-identified adenoma. With the help of ioPTH, a focused parathyroidectomy was accomplished in 43% of scan-negative patients with a solitary adenoma. In conclusion, sestamibi scintigraphy is an acceptable method for localizing a solitary parathyroid adenoma. However, the technique alone does not reliably predict multiglandular disease. Potentially the failure rate in scan-directed parathyroidectomy could increase, with up to 10% of patients without ioPTH.

Scanning AC Nanocalorimetry and Its Applications

NASA Astrophysics Data System (ADS)

Xiao, Kechao

This thesis presents an AC nanocalorimetry technique that enables calorimetry measurements on very small quantities of materials over a wide range of scanning rates (from isothermal to 3x10. 3 K/s), temperatures(up to 1200 K), and environments. Such working range bridges the gap between traditional scanning calorimetry of bulk materials and nanocalorimetry. The method relies on a micromachined nanocalorimeter with negligible thermal lags between heater, thermometer, and sample. The ability to perform calorimetry measurements over such a broad range of scanning rates makes it an ideal tool to characterize the kinetics of phase transformations, reactions at elevated temperatures or to explore the behavior of materials far from equilibrium. We demonstrate the technique by performing measurements on thin-film samples of Sn, In, and Bi with thicknesses ranging from 100 to 300 nm. The experimental heat capacities and melting temperatures agree well with literature values. The measured heat capacities are insensitive to the applied AC frequency, scan rate, and heat loss to the environment over a broad range of experimental conditions. The dynamic range of scanning AC nanocalorimetry enables the combination of nanocalorimetry with in-situ x-ray diffraction (XRD) to facilitate interpretation of the calorimetry measurements. Time-resolved XRD during in-situ operation of nanocalorimetry sensors using intense, high-energy synchrotron radiation allows unprecedented characterization of thermal and structural material properties. We demonstrate this experiment with detailed characterization of the melting and solidification of elemental Bi, In and Sn thin-film samples, using heating and cooling rates up to 300 K/s. By combining scanning DC and AC nano-calorimetry techniques, we study the nucleation behavior of undercooled liquid Bi at cooling rates ranging from 10. 1 to 10. 4 K/s. Upon initial melting, the Bi thin-film sample breaksup into isolated islands. The number of islands in a typical sample is sufficiently large that highly repeatable nucleation behavior is observed, despite the stochastic nature of the nucleation process. We establish a data reduction technique to evaluate the nucleation rate from DC and AC calorimetry results. The results show that the driving force for the nucleation of melted Bi is well described by classical nucleation theory over a wide range of cooling rates. The proposed technique provides a unique and efficient way to examine nucleation kinetics with cooling rates over several orders of magnitude. The technique is quite general and can be used to evaluate reaction kinetics in other materials. Lastly, we apply the scanning AC nanocalorimetry technique to study solid-gas phase reactions by measuring the change in heat capacity of a sample during reaction. We apply this approach to evaluate the oxidation kinetics of thin-film samples of zirconium in air. The results confirm parabolic oxidation kinetics with an activation energy of 0.59+/-0.03 eV. The nano-calorimetry measurements were performed using a device that contains an array of micromachined nano-calorimeter sensors in an architecture designed for combinatorial studies. We demonstrate that the oxidation kinetics can be quantified using a single sample, thus enabling high-throughput mapping of the composition-dependence of the reaction rate.

High-speed AFM for scanning the architecture of living cells

NASA Astrophysics Data System (ADS)

Li, Jing; Deng, Zhifeng; Chen, Daixie; Ao, Zhuo; Sun, Quanmei; Feng, Jiantao; Yin, Bohua; Han, Li; Han, Dong

2013-08-01

We address the modelling of tip-cell membrane interactions under high speed atomic force microscopy. Using a home-made device with a scanning area of 100 × 100 μm2, in situ imaging of living cells is successfully performed under loading rates from 1 to 50 Hz, intending to enable detailed descriptions of physiological processes in living samples.We address the modelling of tip-cell membrane interactions under high speed atomic force microscopy. Using a home-made device with a scanning area of 100 × 100 μm2, in situ imaging of living cells is successfully performed under loading rates from 1 to 50 Hz, intending to enable detailed descriptions of physiological processes in living samples. Electronic supplementary information (ESI) available: Movie of the real-time change of inner surface within fresh blood vessel. The movie was captured at a speed of 30 Hz in the range of 80 μm × 80 μm. See DOI: 10.1039/c3nr01464a

Optical instruments

NASA Technical Reports Server (NTRS)

Abel, I. R. (Inventor)

1974-01-01

A wide angle, low focal ratio, high resolution, catoptric, image plane scanner is described. The scanner includes the following features: (1) a reflective improvement on the Schmidt principle, (2) a polar line scanner in which all field elements are brought to and corrected on axis, and (3) a scanner arrangement in which the aperture stop of the system is imaged at the center of curvature of a spherical primary mirror. The system scans are a large radial angle and an extremely high rate of speed with relatively small scanning mirrors. Because the system is symmetrical about the optical axis, the obscuration is independent of the scan angle.

PScan 1.0: flexible software framework for polygon based multiphoton microscopy

NASA Astrophysics Data System (ADS)

Li, Yongxiao; Lee, Woei Ming

2016-12-01

Multiphoton laser scanning microscopes exhibit highly localized nonlinear optical excitation and are powerful instruments for in-vivo deep tissue imaging. Customized multiphoton microscopy has a significantly superior performance for in-vivo imaging because of precise control over the scanning and detection system. To date, there have been several flexible software platforms catered to custom built microscopy systems i.e. ScanImage, HelioScan, MicroManager, that perform at imaging speeds of 30-100fps. In this paper, we describe a flexible software framework for high speed imaging systems capable of operating from 5 fps to 1600 fps. The software is based on the MATLAB image processing toolbox. It has the capability to communicate directly with a high performing imaging card (Matrox Solios eA/XA), thus retaining high speed acquisition. The program is also designed to communicate with LabVIEW and Fiji for instrument control and image processing. Pscan 1.0 can handle high imaging rates and contains sufficient flexibility for users to adapt to their high speed imaging systems.

Multi-MHz laser-scanning single-cell fluorescence microscopy by spatiotemporally encoded virtual source array

PubMed Central

Wu, Jianglai; Tang, Anson H. L.; Mok, Aaron T. Y.; Yan, Wenwei; Chan, Godfrey C. F.; Wong, Kenneth K. Y.; Tsia, Kevin K.

2017-01-01

Apart from the spatial resolution enhancement, scaling of temporal resolution, equivalently the imaging throughput, of fluorescence microscopy is of equal importance in advancing cell biology and clinical diagnostics. Yet, this attribute has mostly been overlooked because of the inherent speed limitation of existing imaging strategies. To address the challenge, we employ an all-optical laser-scanning mechanism, enabled by an array of reconfigurable spatiotemporally-encoded virtual sources, to demonstrate ultrafast fluorescence microscopy at line-scan rate as high as 8 MHz. We show that this technique enables high-throughput single-cell microfluidic fluorescence imaging at 75,000 cells/second and high-speed cellular 2D dynamical imaging at 3,000 frames per second, outperforming the state-of-the-art high-speed cameras and the gold-standard laser scanning strategies. Together with its wide compatibility to the existing imaging modalities, this technology could empower new forms of high-throughput and high-speed biological fluorescence microscopy that was once challenged. PMID:28966855

Evaluation of the reproducibility of lung motion probability distribution function (PDF) using dynamic MRI.

PubMed

Cai, Jing; Read, Paul W; Altes, Talissa A; Molloy, Janelle A; Brookeman, James R; Sheng, Ke

2007-01-21

Treatment planning based on probability distribution function (PDF) of patient geometries has been shown a potential off-line strategy to incorporate organ motion, but the application of such approach highly depends upon the reproducibility of the PDF. In this paper, we investigated the dependences of the PDF reproducibility on the imaging acquisition parameters, specifically the scan time and the frame rate. Three healthy subjects underwent a continuous 5 min magnetic resonance (MR) scan in the sagittal plane with a frame rate of approximately 10 f s-1, and the experiments were repeated with an interval of 2 to 3 weeks. A total of nine pulmonary vessels from different lung regions (upper, middle and lower) were tracked and the dependences of their displacement PDF reproducibility were evaluated as a function of scan time and frame rate. As results, the PDF reproducibility error decreased with prolonged scans and appeared to approach equilibrium state in subjects 2 and 3 within the 5 min scan. The PDF accuracy increased in the power function with the increase of frame rate; however, the PDF reproducibility showed less sensitivity to frame rate presumably due to the randomness of breathing which dominates the effects. As the key component of the PDF-based treatment planning, the reproducibility of the PDF affects the dosimetric accuracy substantially. This study provides a reference for acquiring MR-based PDF of structures in the lung.

Aging and loading rate effects on the mechanical behavior of equine bone

NASA Astrophysics Data System (ADS)

Kulin, Robb M.; Jiang, Fengchun; Vecchio, Kenneth S.

2008-06-01

Whether due to a sporting accident, high-speed impact, fall, or other catastrophic event, the majority of clinical bone fractures occur under dynamic loading conditions. However, although extensive research has been performed on the quasi-static fracture and mechanical behavior of bone to date, few high-quality studies on the fracture behavior of bone at high strain rates have been performed. Therefore, many questions remain regarding the material behavior, including not only the loading-rate-dependent response of bone, but also how this response varies with age. In this study, tests were performed on equine femoral bone taken post-mortem from donors 6 months to 28 years of age. Quasi-static and dynamic tests were performed to determine the fracture toughness and compressive mechanical behavior as a function of age at varying loading rates. Fracture paths were then analyzed using scanning confocal and scanning-electron microscopy techniques to assess the role of various microstructural features on toughening mechanisms.

Visualization of hair follicles using high-speed optical coherence tomography based on a Fourier domain mode locking laser

NASA Astrophysics Data System (ADS)

Tsai, M.-T.; Chang, F.-Y.

2012-04-01

In this study, a swept-source optical coherence tomography (SS-OCT) system with a Fourier domain mode locking (FDML) laser is proposed for a dermatology study. The homemade FDML laser is one kind of frequency-sweeping light source, which can provide output power of >20 mW and an output spectrum of 65 nm in bandwidth centered at 1300 nm, enabling imaging with an axial resolution of 12 μm in the OCT system. To eliminate the forward scans from the laser output and insert the delayed backward scans, a Mach-Zehnder configuration is implemented. Compared with conventional frequency-sweeping light sources, the FDML laser can achieve much higher scan rates, as high as ˜240 kHz, which can provide a three-dimensional imaging rate of 4 volumes/s. Furthermore, the proposed high-speed SS-OCT system can provide three-dimensional (3D) images with reduced motion artifacts. Finally, a high-speed SS-OCT system is used to visualize hair follicles, demonstrating the potential of this technology as a tool for noninvasive diagnosis of alopecia.

High rate performance supercapacitor based on Nb2O5 nanoparticles

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Ahmed, Ahsan; Rafat, M.

2018-05-01

In the present communication, we report the successful preparation of Nb2O5 nanoparticles from precursor NbCl5 using hydrothermal method, followed by thermal annealing. The surface morphology of the as-prepared material was studied using scanning electron microscopy (SEM) while crystal structure and vibrational response was characterized using X-ray diffraction (XRD) and Raman spectroscopy. The observed results indicate the successful synthesis of Nb2O5 nanoparticles. The electrochemical properties of the material was investigated in two-electrode assembly in 1 M LiClO4 solution using the techniques of electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Both EIS and CV studies show high rate performance of the assembled supercapacitor cells. Fabricated cell offers low response time (˜17.1 ms), and the shape of CV pattern remains almost rectangular, even for high scan rates (˜20 V s-1).

In-situ Crystallization of Highly Volatile Commercial Mold Flux Using an Isolated Observation System in the Confocal Laser Scanning Microscope

NASA Astrophysics Data System (ADS)

Park, Jun-Yong; Ryu, Jae Wook; Sohn, Il

2014-08-01

The in situ crystallization behavior of highly volatile commercial mold fluxes for medium carbon steels was investigated using the confocal laser scanning microscope (CLSM) equipped with an optimized isolated observation system. The highly volatile compounds of the mold flux were suppressed during heating allowing direct observation in the CLSM. Cooling rates of 25, 50, 100, 400, and 800 K/min were incorporated and continuous cooling transformation (CCT) diagrams of 4 different commercial mold fluxes for medium carbon steels were developed. Identification of the crystalline phase was conducted with XRD and SEM-EDS analysis. A cuspidine crystalline was observed in all samples at various cooling rates. With higher basicity, CaF2, and NaF, the crystallization of the fluxes was enhanced according to the CCT diagram. As the slag structure becomes depolymerized, the diffusion rate of the cathodic ions seems to increase.

A fast MEMS scanning photoacoustic microscopy system and its application in glioma study

NASA Astrophysics Data System (ADS)

Bi, Renzhe; Balasundaram, Ghayathri; Jeon, Seungwan; Pu, Yang; Tay, Hui Chien; Kim, Chulhong; Olivo, Malini

2018-02-01

We present a water-proof Microelectromechanical systems (MEMS) based scanning optical resolution Photoacoustic Microscopy (OR-PAM) system and its application in glioma tumor mouse model study. The presented OR-PAM system has high optical resolution ( 3 μm) and high scanning speed (up to 50 kHz A-scan rate), which is ideal for cerebral vascular imaging. In this study, the mice with glioma tumor are treated with vascular disrupting agent (VDA). OR-PAM system is utilized to image the cerebral with the whole skull intact before and after the injection of VDA. By image registration, the response of every single blood vessel can be traced. This will provide us deeper understanding of the drug effect.

Scanning two-photon continuous flow lithography for synthesis of high-resolution 3D microparticles.

PubMed

Shaw, Lucas A; Chizari, Samira; Shusteff, Maxim; Naghsh-Nilchi, Hamed; Di Carlo, Dino; Hopkins, Jonathan B

2018-05-14

Demand continues to rise for custom-fabricated and engineered colloidal microparticles across a breadth of application areas. This paper demonstrates an improvement in the fabrication rate of high-resolution 3D colloidal particles by using two-photon scanning lithography within a microfluidic channel. To accomplish this, we present (1) an experimental setup that supports fast, 3D scanning by synchronizing a galvanometer, piezoelectric stage, and an acousto-optic switch, and (2) a new technique for modifying the laser's scan path to compensate for the relative motion of the rapidly-flowing photopolymer medium. The result is an instrument that allows for rapid conveyor-belt-like fabrication of colloidal objects with arbitrary 3D shapes and micron-resolution features.

Multi-MHz FDML OCT: snapshot retinal imaging at 6.7 million axial-scans per second

NASA Astrophysics Data System (ADS)

Klein, Thomas; Wieser, Wolfgang; André, Raphael; Pfeiffer, Tom; Eigenwillig, Christoph M.; Huber, Robert

2012-01-01

We demonstrate the acquisition of densely sampled wide-field 3D OCT datasets of the human retina in 0.3s. This performance is achieved with a multi-MHz Fourier domain mode-locked (FDML) laser source operating at 1050nm. A two-beam setup doubles the 3.35MHz laser sweep rate to 6.7MHz, which is 16x faster than results achieved with any non-FDML source used for retinal OCT. We discuss two main benefits of these high line rates: First, large datasets over an ultra-wide field of view can be acquired with a low probability of distortions. Second, even if eye movements occur, now the scan rate is high enough to directly correct even the fastest saccades without loss of information.

High spatial resolution LWIR hyperspectral sensor

NASA Astrophysics Data System (ADS)

Roberts, Carson B.; Bodkin, Andrew; Daly, James T.; Meola, Joseph

2015-06-01

Presented is a new hyperspectral imager design based on multiple slit scanning. This represents an innovation in the classic trade-off between speed and resolution. This LWIR design has been able to produce data-cubes at 3 times the rate of conventional single slit scan devices. The instrument has a built-in radiometric and spectral calibrator.

WINCS-BASED WIRELESS ELECTROCHEMICAL MONITORING OF SEROTONIN (5-HT) USING FAST-SCAN CYCLIC VOLTAMMETRY: PROOF OF PRINCIPLE

PubMed Central

Griessenauer, Christoph J.; Chang, Su-Youne; Tye, Susannah J.; Kimble, Christopher J.; Bennet, Kevin E.; Garris, Paul A.; Lee, Kendall H.

2010-01-01

Object We previously reported the development of a Wireless Instantaneous Neurotransmitter Concentration System (WINCS) for measuring dopamine and suggested that this technology may be useful for evaluating deep brain stimulation (DBS)-related neuromodulatory effects on neurotransmitter systems. WINCS supports fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) for real-time, spatially resolved neurotransmitter measurements. The FSCV parameters used to establish WINCS dopamine measurements are not suitable for serotonin, a neurotransmitter implicated in depression, because they lead to CFM fouling and a loss of sensitivity. Here, we incorporate into WINCS a previously described N-shaped waveform applied at a high scan rate to establish wireless serotonin monitoring. Methods FSCV optimized for the detection of serotonin consisted of an N-shaped waveform scanned linearly from a resting potential of, in V, +0.2 to +1.0, then to −0.1 and back to +0.2 at a rate of 1000 V/s. Proof of principle tests included flow injection analysis and electrically evoked serotonin release in the dorsal raphe nucleus of rat brain slices. Results Flow cell injection analysis demonstrated that the N waveform applied at a scan rate of 1000 V/s significantly reduced serotonin fouling of the CFM, relative to that observed with FSCV parameters for dopamine. In brain slices, WINCS reliably detected sub-second serotonin release in the dorsal raphe nucleus evoked by local high-frequency stimulation. Conclusion WINCS supported high-fidelity wireless serotonin monitoring by FSCV at a CFM. In the future such measurements of serotonin in large animal models and in humans may help to establish the mechanism of DBS for psychiatric disease. PMID:20415521

Compact high-speed scanning lidar system

NASA Astrophysics Data System (ADS)

Dickinson, Cameron; Hussein, Marwan; Tripp, Jeff; Nimelman, Manny; Koujelev, Alexander

2012-06-01

The compact High Speed Scanning Lidar (HSSL) was designed to meet the requirements for a rover GN&C sensor. The eye-safe HSSL's fast scanning speed, low volume and low power, make it the ideal choice for a variety of real-time and non-real-time applications including: 3D Mapping; Vehicle guidance and Navigation; Obstacle Detection; Orbiter Rendezvous; Spacecraft Landing / Hazard Avoidance. The HSSL comprises two main hardware units: Sensor Head and Control Unit. In a rover application, the Sensor Head mounts on the top of the rover while the Control Unit can be mounted on the rover deck or within its avionics bay. An Operator Computer is used to command the lidar and immediately display the acquired scan data. The innovative lidar design concept was a result of an extensive trade study conducted during the initial phase of an exploration rover program. The lidar utilizes an innovative scanner coupled with a compact fiber laser and high-speed timing electronics. Compared to existing compact lidar systems, distinguishing features of the HSSL include its high accuracy, high resolution, high refresh rate and large field of view. Other benefits of this design include the capability to quickly configure scan settings to fit various operational modes.

Dynamic scan control in STEM: Spiral scans

DOE PAGES

Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.; ...

2016-06-13

Here, scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging atmore » low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.« less

Dynamic scan control in STEM: Spiral scans

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

Lupini, Andrew R.; Borisevich, Albina Y.; Kalinin, Sergei V.

Here, scanning transmission electron microscopy (STEM) has emerged as one of the foremost techniques to analyze materials at atomic resolution. However, two practical difficulties inherent to STEM imaging are: radiation damage imparted by the electron beam, which can potentially damage or otherwise modify the specimen and slow-scan image acquisition, which limits the ability to capture dynamic changes at high temporal resolution. Furthermore, due in part to scan flyback corrections, typical raster scan methods result in an uneven distribution of dose across the scanned area. A method to allow extremely fast scanning with a uniform residence time would enable imaging atmore » low electron doses, ameliorating radiation damage and at the same time permitting image acquisition at higher frame-rates while maintaining atomic resolution. The practical complication is that rastering the STEM probe at higher speeds causes significant image distortions. Non-square scan patterns provide a solution to this dilemma and can be tailored for low dose imaging conditions. Here, we develop a method for imaging with alternative scan patterns and investigate their performance at very high scan speeds. A general analysis for spiral scanning is presented here for the following spiral scan functions: Archimedean, Fermat, and constant linear velocity spirals, which were tested for STEM imaging. The quality of spiral scan STEM images is generally comparable with STEM images from conventional raster scans, and the dose uniformity can be improved.« less

Ground Based Operational Testing Of Holographic Scanning Lidars : The HOLO Experiments

NASA Technical Reports Server (NTRS)

Schwemmer, Geary K.; Wilkerson, Thomas D.; Sanders, Jason A.; Guerra, David V.; Miller, David O.; Moody, Stephen E.

2000-01-01

Two aerosol backscatter lidar measurement campaigns were conducted using two holographic scanning lidars and one zenith staring lidar for the purposes of reliability testing under field conditions three new lidar systems and to develop new scanning measurement techniques and applications. The first campaign took place near the campus of Utah State University in Logan Utah in March of 1999 and is called HOLO-1. HOLO-2 was conducted in June of 1999 on the campus of Saint Anselm College, near the city of Manchester, New Hampshire. Each campaign covered a period of approximately one week of nearly continuous observation of cloud and aerosol backscatter in the visible and near infrared by lidar, and wide field visible sky images by video camera in the daytime. The scanning capability coupled with a high rep-rate, high average power laser enables both high spatial and high temporal resolution observations that Particularly intriguing is the possibility of deriving atmospheric wind profiles from temporal analysis of aerosol backscatter spatial structure obtained by conical scan without the use of Doppler techniques.

Relationship between the Self-Rating Anxiety Scale score and the success rate of 64-slice computed tomography coronary angiography.

PubMed

Li, Hui; Jin, Dan; Qiao, Fang; Chen, Jianchang; Gong, Jianping

Computed tomography coronary angiography, a key method for obtaining coronary artery images, is widely used to screen for coronary artery diseases due to its noninvasive nature. In China, 64-slice computed tomography systems are now the most common models. As factors that directly affect computed tomography performance, heart rate and rhythm control are regulated by the autonomic nervous system and are highly related to the emotional state of the patient. The aim of this prospective study is to use a pre-computed tomography scan Self-Rating Anxiety Scale assessment to analyze the effects of tension and anxiety on computed tomography coronary angiography success. Subjects aged 18-85 years who were planned to undergo computed tomography coronary angiography were enrolled; 1 to 2 h before the computed tomography scan, basic patient data (gender, age, heart rate at rest, and family history) and Self-Rating Anxiety Scale score were obtained. The same group of imaging department doctors, technicians, and nurses performed computed tomography coronary angiography for all the enrolled subjects and observed whether those subjects could finish the computed tomography coronary angiography scan and provide clear, diagnostically valuable images. Participants were divided into successful (obtained diagnostically useful coronary images) and unsuccessful groups. Basic data and Self-Rating Anxiety Scale scores were compared between the groups. The Self-Rating Anxiety Scale standard score of the successful group was lower than that of the unsuccessful group (P = 0.001). As the Self-Rating Anxiety Scale standard score rose, the success rate of computed tomography coronary angiography decreased. The Self-Rating Anxiety Scale score has a negative relationship with computed tomography coronary angiography success. Anxiety can be a disadvantage in computed tomography coronary angiography examination. The pre-computed tomography coronary angiography scan Self-Rating Anxiety Scale score may be a useful tool for assessing whether a computed tomography coronary angiography scan will be successful or not. © The Author(s) 2015.

4D spiral imaging of flows in stenotic phantoms and subjects with aortic stenosis.

PubMed

Negahdar, M J; Kadbi, Mo; Kendrick, Michael; Stoddard, Marcus F; Amini, Amir A

2016-03-01

The utility of four-dimensional (4D) spiral flow in imaging of stenotic flows in both phantoms and human subjects with aortic stenosis is investigated. The method performs 4D flow acquisitions through a stack of interleaved spiral k-space readouts. Relative to conventional 4D flow, which performs Cartesian readout, the method has reduced echo time. Thus, reduced flow artifacts are observed when imaging high-speed stenotic flows. Four-dimensional spiral flow also provides significant savings in scan times relative to conventional 4D flow. In vitro experiments were performed under both steady and pulsatile flows in a phantom model of severe stenosis (one inch diameter at the inlet, with 87% area reduction at the throat of the stenosis) while imaging a 6-cm axial extent of the phantom, which included the Gaussian-shaped stenotic narrowing. In all cases, gradient strength and slew rate for standard clinical acquisitions, and identical field of view and resolution were used. For low steady flow rates, quantitative and qualitative results showed a similar level of accuracy between 4D spiral flow (echo time [TE] = 2 ms, scan time = 40 s) and conventional 4D flow (TE = 3.6 ms, scan time = 1:01 min). However, in the case of high steady flow rates, 4D spiral flow (TE = 1.57 ms, scan time = 38 s) showed better visualization and accuracy as compared to conventional 4D flow (TE = 3.2 ms, scan time = 51 s). At low pulsatile flow rates, a good agreement was observed between 4D spiral flow (TE = 2 ms, scan time = 10:26 min) and conventional 4D flow (TE = 3.6 ms, scan time = 14:20 min). However, in the case of high flow-rate pulsatile flows, 4D spiral flow (TE = 1.57 ms, scan time = 10:26 min) demonstrated better visualization as compared to conventional 4D flow (TE = 3.2 ms, scan time = 14:20 min). The feasibility of 4D spiral flow was also investigated in five normal volunteers and four subjects with mild-to-moderate aortic stenosis. The approach achieved TE = 1.68 ms and scan time = 3:44 min. The conventional sequence achieved TE = 2.9 ms and scan time = 5:23 min. In subjects with aortic stenosis, we also compared both MRI methods with Doppler ultrasound (US) in the measurement of peak velocity, time to peak systolic velocity, and eject time. Bland-Altman analysis revealed that, when comparing peak velocities, the discrepancy between Doppler US and 4D spiral flow was significantly less than the discrepancy between Doppler and 4D Cartesian flow (2.75 cm/s vs. 10.25 cm/s), whereas the two MR methods were comparable (-5.75 s vs. -6 s) for time to peak. However, for the estimation of eject time, relative to Doppler US, the discrepancy for 4D conventional flow was smaller than that of 4D spiral flow (-16.25 s vs. -20 s). Relative to conventional 4D flow, 4D spiral flow achieves substantial reductions in both the TE and scan times; therefore, utility for it should be sought in a variety of in vivo and complex flow imaging applications. © 2015 Wiley Periodicals, Inc.

Use of Bone Scan During Initial Prostate Cancer Workup, Downstream Procedures, and Associated Medicare Costs

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

Falchook, Aaron D.; Salloum, Ramzi G.; Hendrix, Laura H.

Purpose: For patients with a high likelihood of having metastatic disease (high-risk prostate cancer), bone scan is the standard, guideline-recommended test to look for bony metastasis. We quantified the use of bone scans and downstream procedures, along with associated costs, in patients with high-risk prostate cancer, and their use in low- and intermediate-risk patients for whom these tests are not recommended. Methods and Materials: Patients in the Surveillance, Epidemiology, and End Results (SEER)-Medicare database diagnosed with prostate cancer from 2004 to 2007 were included. Prostate specific antigen (PSA), Gleason score, and clinical T stage were used to define D'Amico riskmore » categories. We report use of bone scans from the date of diagnosis to the earlier of treatment or 6 months. In patients who underwent bone scans, we report use of bone-specific x-ray, computed tomography (CT), and magnetic resonance imaging (MRI) scans, and bone biopsy within 3 months after bone scan. Costs were estimated using 2012 Medicare reimbursement rates. Results: In all, 31% and 48% of patients with apparent low- and intermediate-risk prostate cancer underwent a bone scan; of these patients, 21% underwent subsequent x-rays, 7% CT, and 3% MRI scans. Bone biopsies were uncommon. Overall, <1% of low- and intermediate-risk patients were found to have metastatic disease. The annual estimated Medicare cost for bone scans and downstream procedures was $11,300,000 for low- and intermediate-risk patients. For patients with apparent high-risk disease, only 62% received a bone scan, of whom 14% were found to have metastasis. Conclusions: There is overuse of bone scans in patients with low- and intermediate-risk prostate cancers, which is unlikely to yield clinically actionable information and results in a potential Medicare waste. However, there is underuse of bone scans in high-risk patients for whom metastasis is likely.« less

Error mapping of high-speed AFM systems

NASA Astrophysics Data System (ADS)

Klapetek, Petr; Picco, Loren; Payton, Oliver; Yacoot, Andrew; Miles, Mervyn

2013-02-01

In recent years, there have been several advances in the development of high-speed atomic force microscopes (HSAFMs) to obtain images with nanometre vertical and lateral resolution at frame rates in excess of 1 fps. To date, these instruments are lacking in metrology for their lateral scan axes; however, by imaging a series of two-dimensional lateral calibration standards, it has been possible to obtain information about the errors associated with these HSAFM scan axes. Results from initial measurements are presented in this paper and show that the scan speed needs to be taken into account when performing a calibration as it can lead to positioning errors of up to 3%.

Diffusion weighted imaging: a comprehensive evaluation of a fast spin echo DWI sequence with BLADE (PROPELLER) k-space sampling at 3 T, using a 32-channel head coil in acute brain ischemia.

PubMed

Attenberger, Ulrike I; Runge, Val M; Stemmer, Alto; Williams, Kenneth D; Naul, L Gill; Michaely, Henrik J; Schoenberg, Stefan O; Reiser, Maximilian F; Wintersperger, Bernd J

2009-10-01

To evaluate the signal-to-noise ratio (SNR) and diagnostic quality of diffusion weighted imaging (DWI) using a fast spin echo (FSE) sequence with BLADE k-space trajectory at 3 T in combination with a 32-channel head coil. The scan was compared with a standard spin echo (SE) echo-planar imaging (EPI) DWI and a high resolution SE EPI DWI sequence. Fourteen patients with acute brain ischemia were included in this Institutional Review Board approved study. All patients were evaluated with 3 different image sequences, using a 3 T scanner and a 32-channel head coil: (a) a standard SE EPI DWI (matrix size 192 x 192), (b) a high resolution SE EPI DWI (matrix size of 256 x 256) and (c) a FSE DWI BLADE (matrix size 192 x 192). The SNR of the 3 scans was compared in 10 healthy volunteers by a paired student t test. Image quality was evaluated with 4 dedicated questions in a blinded read: (1) The scans were ranked in terms of bulk susceptibility artifact. (2) The scan preference for diagnosis of any diffusion abnormality that might occur and (3) the preference for visualization of the diffusion abnormality actually present was determined. (4) The influence of bulk susceptibility on image evaluation for the diffusion abnormality present was assessed. For visualization of the diffusion abnormality present, BLADE DWI was the scan sequence preferred most by both readers (reader 1: 41.7%, reader 2: 35.7%). For visualization of any diffusion abnormality present, BLADE DWI was the preferred scan in 13 of 14 cases for reader 1 (93%) and in 11 of 14 cases for reader 2 (78.6%). No high resolution SE EPI DWI scan was rated best by reader 1. Reader 2 rated the high resolution SE EPI DWI scan superior in only 1 of 56 judgments. The standard EPI DWI sequence (21.8 +/- 5.3) had in comparison to the high resolution EPI DWI (11.9 +/- 2.6) and the BLADE DWI scans (11.3 +/- 3.8) significantly higher SNR mean values. Our preliminary data demonstrates the feasibility of a FSE EPI DWI scan with radial-like k-space sampling, using a 32-channel coil at 3 T in acute brain ischemia. The BLADE DWI was the preferred scan for the detection of acute diffusion abnormalities because of the lack of bulk susceptibility artifacts.

Advanced optical diagnostics of multiphase combustion flow field using OH planar laser-induced fluorescence

NASA Astrophysics Data System (ADS)

Cho, Kevin Young-jin

High-repetition-rate (5 kHz, 10 kHz) OH planar laser induced fluorescence (PLIF) was used to investigate the combustion of liquid, gelled, and solid propellants. For the liquid monomethyl hydrazine (MMH) droplet combustion experiment in N2O/N2 using 5 kHz OH PLIF and visible imaging system, the OH profile and the droplet diameter were measured. The N2O partial pressure was varied by 20% and 40%, and the total pressure was varied by 103, 172, 276, 414, 552 kPa. The OH location indicated that the oxidation flame front is between the visible dual flame fronts. The results showed thicker flame sheet and higher burning rate for increased N2O concentration for a given pressure. The burning rate increased with increased pressure at 20% partial pressure N2O, and the burning rate decreased with increased pressure at 40% partial pressure N2O. This work provides experimental data for validating chemical kinetics models. For the gelled droplet combustion experiment using a 5 kHz OH PLIF system, speeds and locations of fuel jets emanating from the burning gelled droplets were quantified for the first time. MMH was gelled with organic gellant HPC at 3 wt.% and 6 wt.%, and burned in air at 35, 103, 172, 276, and 414 kPa. Different types of interaction of vapor jets and flame front were distinguished for the first time. For high jet speed, local extinction of the flame was observed. By analyzing the jet speed statistics, it was concluded that pressure and jet speed had an inverse relationship and gellant concentration and jet speed had a direct relationship. This work provides more fundamental insight into the physics of gelled fuel droplet combustion. A 3D OH PLIF system was assembled and demonstrated using a 10 kHz OH PLIF system and a galvanometric scanning mirror. This is the first time that a reacting flow field was imaged with a 3D optical technique using OH PLIF. A 3D scan time of 1 ms was achieved, with ten slices generated per sweep with 1000 Hz scan rate. Alternatively, 3D scan time of 500 micros was achieved with a trapezoidal scan profile, generating five new slices per sweep at 1000 Hz scan rate. The system was applied to 3 wt.% and 6 wt.% HPC methanol gelled droplet combustion in 1 atm, and at room temperature. The system had sufficient spatial and temporal resolution to provide a more complete picture of the complex asymmetrical and random flame structure of the gelled droplet combustion. However, the technique had limited capabilities for resolving the impinging jet spray combustion flow field. For the ammonium perchlorate (AP)/ hydroxyl-terminated polybutadiene (HTPB) combustion study with 3D OH PLIF, 40 wt.% coarse AP crystal (400 microm), 40 wt.% fine AP crystal (20 microm), and 20 wt.% HTPB binder formulation with pellet diameter of 6.35 mm was used. The scan rate was reduced to 250 Hz, resulting in 20 images generated per scan, 500 scans per second, and 2 ms scan time, with 1.5 mm scan distance. The test pressure ranged from 3.4 - 6.1 atm of nitrogen, with test temperature at room condition. The results from 3D OH PLIF of AP/HTPB combustion showed a diffusion flame structure, with a lack of OH in the middle of the flame. This is the first time a direct observation of the diffusion flame and the OH structure have been made at elevated pressure. The preliminary results show a good agreement with the BDP model, with a second order increase in the diffusion flame height with increased coarse crystal diameter. Although the scan of 3D OH PLIF is non-instantaneous, no other systems in the literature can scan reacting flow field at such a high 3D repetition rate. Since the identification of the transient flame patterns is facilitated by the ability to visualize the flame front at multiple planes, the 3D OH PLIF technique offers great promise as a diagnostic for dynamic combustion events.

Binder-free three-dimensional high energy density electrodes for ionic-liquid supercapacitors.

PubMed

Tran, Chau; Lawrence, Daniel; Richey, Francis W; Dillard, Caitlin; Elabd, Yossef A; Kalra, Vibha

2015-09-18

We demonstrate a facile methodology to fabricate binder-free porous carbon nanofiber electrodes for room temperature ionic-liquid supercapacitors. The device provides an energy density of 80 W h kg(-1) based on the mass of two electrodes while retaining the high rate capability of supercapacitors with near-ideal CV curves at a high scan rate of 200 mV s(-1).

Feasibility of large volume tumor ablation using multiple-mode strategy with fast scanning method: A numerical study

NASA Astrophysics Data System (ADS)

Wu, Hao; Shen, Guofeng; Qiao, Shan; Chen, Yazhu

2017-03-01

Sonication with fast scanning method can generate homogeneous lesions without complex planning. But when the target region is large, switching focus too fast will reduce the heat accumulation, the margin of which may not ablated. Furthermore, high blood perfusion rate will reduce this maximum volume that can be ablated. Therefore, fast scanning method may not be applied to large volume tumor. To expand the therapy scope, this study combines the fast scan method with multiple mode strategy. Through simulation and experiment, the feasibility of this new strategy is evaluated and analyzed.

High resolution, high frame rate video technology development plan and the near-term system conceptual design

NASA Technical Reports Server (NTRS)

Ziemke, Robert A.

1990-01-01

The objective of the High Resolution, High Frame Rate Video Technology (HHVT) development effort is to provide technology advancements to remove constraints on the amount of high speed, detailed optical data recorded and transmitted for microgravity science and application experiments. These advancements will enable the development of video systems capable of high resolution, high frame rate video data recording, processing, and transmission. Techniques such as multichannel image scan, video parameter tradeoff, and the use of dual recording media were identified as methods of making the most efficient use of the near-term technology.

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

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

Coquelle, Nicolas; CNRS, IBS, 38044 Grenoble; CEA, IBS, 38044 Grenoble

A raster scanning serial protein crystallography approach is presented, that consumes as low ∼200–700 nl of sedimented crystals. New serial data pre-analysis software, NanoPeakCell, is introduced. High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able tomore » read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.« less

Correlation between the clinical pretest probability score and the lung ventilation and perfusion scan probability.

PubMed

Bhoobalan, Shanmugasundaram; Chakravartty, Riddhika; Dolbear, Gill; Al-Janabi, Mazin

2013-10-01

Aim of the study was to determine the accuracy of the clinical pretest probability (PTP) score and its association with lung ventilation and perfusion (VQ) scan. A retrospective analysis of 510 patients who had a lung VQ scan between 2008 and 2010 were included in the study. Out of 510 studies, the number of normal, low, and high probability VQ scans were 155 (30%), 289 (57%), and 55 (11%), respectively. A total of 103 patients underwent computed tomography pulmonary angiography (CTPA) scan in which 21 (20%) had a positive scan, 81 (79%) had a negative scan and one (1%) had an equivocal result. The rate of PE in the normal, low-probability, and high-probability scan categories were: 2 (9.5%), 10 (47.5%), and 9 (43%) respectively. A very low correlation (Pearson correlation coefficient r = 0.20) between the clinical PTP score and lung VQ scan. The area under the curve (AUC) of the clinical PTP score was 52% when compared with the CTPA results. However, the accuracy of lung VQ scan was better (AUC = 74%) when compared with CTPA scan. The clinical PTP score is unreliable on its own; however, it may still aid in the interpretation of lung VQ scan. The accuracy of the lung VQ scan was better in the assessment of underlying pulmonary embolism (PE).

Correlation between the clinical pretest probability score and the lung ventilation and perfusion scan probability

PubMed Central

Bhoobalan, Shanmugasundaram; Chakravartty, Riddhika; Dolbear, Gill; Al-Janabi, Mazin

2013-01-01

Purpose: Aim of the study was to determine the accuracy of the clinical pretest probability (PTP) score and its association with lung ventilation and perfusion (VQ) scan. Materials and Methods: A retrospective analysis of 510 patients who had a lung VQ scan between 2008 and 2010 were included in the study. Out of 510 studies, the number of normal, low, and high probability VQ scans were 155 (30%), 289 (57%), and 55 (11%), respectively. Results: A total of 103 patients underwent computed tomography pulmonary angiography (CTPA) scan in which 21 (20%) had a positive scan, 81 (79%) had a negative scan and one (1%) had an equivocal result. The rate of PE in the normal, low-probability, and high-probability scan categories were: 2 (9.5%), 10 (47.5%), and 9 (43%) respectively. A very low correlation (Pearson correlation coefficient r = 0.20) between the clinical PTP score and lung VQ scan. The area under the curve (AUC) of the clinical PTP score was 52% when compared with the CTPA results. However, the accuracy of lung VQ scan was better (AUC = 74%) when compared with CTPA scan. Conclusion: The clinical PTP score is unreliable on its own; however, it may still aid in the interpretation of lung VQ scan. The accuracy of the lung VQ scan was better in the assessment of underlying pulmonary embolism (PE). PMID:24379532

Design, fabrication, and evaluation of on-chip micro-supercapacitors

NASA Astrophysics Data System (ADS)

Beidaghi, Majid

Due to the increasing demand for high power and reliable miniaturized energy storage devices, the development of micro-supercapacitors or electrochemical micro-capacitors have attracted much attention in recent years. This dissertation investigates several strategies to develop on-chip micro-supercapacitors with high power and energy density. Micro-supercapacitors based on interdigitated carbon micro-electrode arrays are fabricated through carbon microelectromechanical systems (C-MEMS) technique which is based on carbonization of patterned photoresist. To improve the capacitive behavior, electrochemical activation is performed on carbon micro-electrode arrays. The developed micro-supercapacitors show specific capacitances as high as 75 mFcm-2 at a scan rate of 5 mVs -1 after electrochemical activation for 30 minutes. The capacitance loss is less than 13% after 1000 cyclic voltammetry (CV) cycles. These results indicate that electrochemically activated C-MEMS micro-electrode arrays are promising candidates for on-chip electrochemical micro-capacitor applications. The energy density of micro-supercapacitors was further improved by conformal coating of polypyrrole (PPy) on C-MEMS structures. In these types of micro-devices the three dimensional (3D) carbon microstructures serve as current collectors for high energy density PPy electrodes. The electrochemical characterizations of these micro-supercapacitors show that they can deliver a specific capacitance of about 162.07 mFcm-2 and a specific power of 1.62mWcm -2 at a 20 mVs-1 scan rate. Addressing the need for high power micro-supercapacitors, the application of graphene as electrode materials for micro-supercapacitor was also investigated. The present study suggests a novel method to fabricate graphene-based micro-supercapacitors with thin film or in-plane interdigital electrodes. The fabricated micro-supercapacitors show exceptional frequency response and power handling performance and could effectively charge and discharge at rates as high as 50 Vs-1. CV measurements show that the specific capacitance of the micro-supercapacitor based on reduced graphene oxide and carbon nanotube composites is 6.1 mFcm -2 at scan rate of 0.01Vs-1. At a very high scan rate of 50 Vs-1, a specific capacitance of 2.8 mFcm-2 (stack capacitance of 3.1 Fcm-3) is recorded. This unprecedented performance can potentially broaden the future applications of micro-supercapacitors.

Ultrahigh speed 1050nm swept source / Fourier domain OCT retinal and anterior segment imaging at 100,000 to 400,000 axial scans per second

PubMed Central

Potsaid, Benjamin; Baumann, Bernhard; Huang, David; Barry, Scott; Cable, Alex E.; Schuman, Joel S.; Duker, Jay S.; Fujimoto, James G.

2011-01-01

We demonstrate ultrahigh speed swept source/Fourier domain ophthalmic OCT imaging using a short cavity swept laser at 100,000–400,000 axial scan rates. Several design configurations illustrate tradeoffs in imaging speed, sensitivity, axial resolution, and imaging depth. Variable rate A/D optical clocking is used to acquire linear-in-k OCT fringe data at 100kHz axial scan rate with 5.3um axial resolution in tissue. Fixed rate sampling at 1 GSPS achieves a 7.5mm imaging range in tissue with 6.0um axial resolution at 100kHz axial scan rate. A 200kHz axial scan rate with 5.3um axial resolution over 4mm imaging range is achieved by buffering the laser sweep. Dual spot OCT using two parallel interferometers achieves 400kHz axial scan rate, almost 2X faster than previous 1050nm ophthalmic results and 20X faster than current commercial instruments. Superior sensitivity roll-off performance is shown. Imaging is demonstrated in the human retina and anterior segment. Wide field 12×12mm data sets include the macula and optic nerve head. Small area, high density imaging shows individual cone photoreceptors. The 7.5mm imaging range configuration can show the cornea, iris, and anterior lens in a single image. These improvements in imaging speed and depth range provide important advantages for ophthalmic imaging. The ability to rapidly acquire 3D-OCT data over a wide field of view promises to simplify examination protocols. The ability to image fine structures can provide detailed information on focal pathologies. The large imaging range and improved image penetration at 1050nm wavelengths promises to improve performance for instrumentation which images both the retina and anterior eye. These advantages suggest that swept source OCT at 1050nm wavelengths will play an important role in future ophthalmic instrumentation. PMID:20940894

Reducing Head CT Use for Children With Head Injuries in a Community Emergency Department.

PubMed

Jennings, Rebecca M; Burtner, Jennifer J; Pellicer, Joseph F; Nair, Deepthi K; Bradford, Miranda C; Shaffer, Michele; Uspal, Neil G; Tieder, Joel S

2017-04-01

Clinical decision rules have reduced use of computed tomography (CT) to evaluate minor pediatric head injury in pediatric emergency departments (EDs). CT use remains high in community EDs, where the majority of children seek medical care. We sought to reduce the rate of CT scans used to evaluate pediatric head injury from 29% to 20% in a community ED. We evaluated a quality improvement (QI) project in a community ED aimed at decreasing the use of head CT scans in children by implementing a validated head trauma prediction rule for traumatic brain injury. A multidisciplinary team identified key drivers of CT use and implemented decision aids to improve the use of prediction rules. The team identified and mitigated barriers. An affiliated children's hospital offered Maintenance of Certification credit and QI coaching to participants. We used statistical process control charts to evaluate the effect of the intervention on monthly CT scan rates and performed a Wald test of equivalence to compare preintervention and postintervention CT scan proportions. The baseline period (February 2013-July 2014) included 695 patients with a CT scan rate of 29.2% (95% confidence interval, 25.8%-32.6%). The postintervention period (August 2014-October 2015) included 651 patients with a CT scan rate of 17.4% (95% confidence interval, 14.5%-20.2%, P < .01). Barriers included targeting providers with variable pediatric experience and parental imaging expectations. We demonstrate that a Maintenance of Certification QI project sponsored by a children's hospital can facilitate evidence-based pediatric care and decrease the rate of unnecessary CT use in a community setting. Copyright © 2017 by the American Academy of Pediatrics.

Electron imaging with an EBSD detector.

PubMed

Wright, Stuart I; Nowell, Matthew M; de Kloe, René; Camus, Patrick; Rampton, Travis

2015-01-01

Electron Backscatter Diffraction (EBSD) has proven to be a useful tool for characterizing the crystallographic orientation aspects of microstructures at length scales ranging from tens of nanometers to millimeters in the scanning electron microscope (SEM). With the advent of high-speed digital cameras for EBSD use, it has become practical to use the EBSD detector as an imaging device similar to a backscatter (or forward-scatter) detector. Using the EBSD detector in this manner enables images exhibiting topographic, atomic density and orientation contrast to be obtained at rates similar to slow scanning in the conventional SEM manner. The high-speed acquisition is achieved through extreme binning of the camera-enough to result in a 5 × 5 pixel pattern. At such high binning, the captured patterns are not suitable for indexing. However, no indexing is required for using the detector as an imaging device. Rather, a 5 × 5 array of images is formed by essentially using each pixel in the 5 × 5 pixel pattern as an individual scattered electron detector. The images can also be formed at traditional EBSD scanning rates by recording the image data during a scan or can also be formed through post-processing of patterns recorded at each point in the scan. Such images lend themselves to correlative analysis of image data with the usual orientation data provided by and with chemical data obtained simultaneously via X-Ray Energy Dispersive Spectroscopy (XEDS). Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

PubMed Central

Coquelle, Nicolas; Brewster, Aaron S.; Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta; Burghammer, Manfred; Colletier, Jacques-Philippe

2015-01-01

High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering. PMID:25945583

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

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

Coquelle, Nicolas; Brewster, Aaron S.; Kapp, Ulrike

High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Åmore » resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.« less

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams.

PubMed

Coquelle, Nicolas; Brewster, Aaron S; Kapp, Ulrike; Shilova, Anastasya; Weinhausen, Britta; Burghammer, Manfred; Colletier, Jacques Philippe

2015-05-01

High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Å resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.

Raster-scanning serial protein crystallography using micro- and nano-focused synchrotron beams

DOE PAGES

Coquelle, Nicolas; Brewster, Aaron S.; Kapp, Ulrike; ...

2015-04-25

High-resolution structural information was obtained from lysozyme microcrystals (20 µm in the largest dimension) using raster-scanning serial protein crystallography on micro- and nano-focused beamlines at the ESRF. Data were collected at room temperature (RT) from crystals sandwiched between two silicon nitride wafers, thereby preventing their drying, while limiting background scattering and sample consumption. In order to identify crystal hits, new multi-processing and GUI-driven Python-based pre-analysis software was developed, named NanoPeakCell, that was able to read data from a variety of crystallographic image formats. Further data processing was carried out using CrystFEL, and the resultant structures were refined to 1.7 Åmore » resolution. The data demonstrate the feasibility of RT raster-scanning serial micro- and nano-protein crystallography at synchrotrons and validate it as an alternative approach for the collection of high-resolution structural data from micro-sized crystals. Advantages of the proposed approach are its thriftiness, its handling-free nature, the reduced amount of sample required, the adjustable hit rate, the high indexing rate and the minimization of background scattering.« less

Prospective multi-center study of an automatic online seizure detection system for epilepsy monitoring units.

PubMed

Fürbass, F; Ossenblok, P; Hartmann, M; Perko, H; Skupch, A M; Lindinger, G; Elezi, L; Pataraia, E; Colon, A J; Baumgartner, C; Kluge, T

2015-06-01

A method for automatic detection of epileptic seizures in long-term scalp-EEG recordings called EpiScan will be presented. EpiScan is used as alarm device to notify medical staff of epilepsy monitoring units (EMUs) in case of a seizure. A prospective multi-center study was performed in three EMUs including 205 patients. A comparison between EpiScan and the Persyst seizure detector on the prospective data will be presented. In addition, the detection results of EpiScan on retrospective EEG data of 310 patients and the public available CHB-MIT dataset will be shown. A detection sensitivity of 81% was reached for unequivocal electrographic seizures with false alarm rate of only 7 per day. No statistical significant differences in the detection sensitivities could be found between the centers. The comparison to the Persyst seizure detector showed a lower false alarm rate of EpiScan but the difference was not of statistical significance. The automatic seizure detection method EpiScan showed high sensitivity and low false alarm rate in a prospective multi-center study on a large number of patients. The application as seizure alarm device in EMUs becomes feasible and will raise the efficiency of video-EEG monitoring and the safety levels of patients. Copyright © 2014 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Effectiveness and Safety of Spot Scanning Proton Radiation Therapy for Chordomas and Chondrosarcomas of the Skull Base: First Long-Term Report

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

Ares, Carmen, E-mail: carmen.ares@psi.c; Hug, Eugen B.; Lomax, Antony J.

2009-11-15

Purpose: To evaluate effectiveness and safety of spot-scanning-based proton radiotherapy (PT) in skull-base chordomas and chondrosarcomas. Methods and Materials: Between October 1998 and November 2005, 64 patients with skull-base chordomas (n = 42) and chondrosarcomas (n = 22) were treated at Paul Scherrer Institute with PT using spot-scanning technique. Median total dose for chordomas was 73.5 Gy(RBE) and 68.4 Gy(RBE) for chondrosarcomas at 1.8-2.0 Gy(RBE) dose per fraction. Local control (LC), disease specific survival (DSS), and overall survival (OS) rates were calculated. Toxicity was assessed according to CTCAE, v. 3.0. Results: Mean follow-up period was 38 months (range, 14-92 months).more » Five patients with chordoma and one patient with chondrosarcoma experienced local recurrence. Actuarial 5-year LC rates were 81% for chordomas and 94% for chondrosarcomas. Brainstem compression at the time of PT (p = 0.007) and gross tumor volume >25 mL (p = 0.03) were associated with lower LC rates. Five years rates of DSS and OS were 81% and 62% for chordomas and 100% and 91% for chondrosarcomas, respectively. High-grade late toxicity consisted of one patient with Grade 3 and one patient with Grade 4 unilateral optic neuropathy, and two patients with Grade 3 central nervous system necrosis. No patient experienced brainstem toxicity. Actuarial 5-year freedom from high-grade toxicity was 94%. Conclusions: Our data indicate safety and efficacy of spot-scanning based PT for skull-base chordomas and chondrosarcomas. With target definition, dose prescription and normal organ tolerance levels similar to passive-scattering based PT series, complication-free, tumor control and survival rates are at present comparable.« less

Scattering-type scanning near-field optical microscopy with low-repetition-rate pulsed light source through phase-domain sampling

PubMed Central

Wang, Haomin; Wang, Le; Xu, Xiaoji G.

2016-01-01

Scattering-type scanning near-field optical microscopy (s-SNOM) allows spectroscopic imaging with spatial resolution below the diffraction limit. With suitable light sources, s-SNOM is instrumental in numerous discoveries at the nanoscale. So far, the light sources have been limited to continuous wave or high-repetition-rate pulsed lasers. Low-repetition-rate pulsed sources cannot be used, due to the limitation of the lock-in detection mechanism that is required for current s-SNOM techniques. Here, we report a near-field signal extraction method that enables low-repetition-rate pulsed light sources. The method correlates scattering signals from pulses with the mechanical phases of the oscillating s-SNOM probe to obtain near-field signal, by-passing the apparent restriction imposed by the Nyquist–Shannon sampling theorem on the repetition rate. The method shall enable s-SNOM with low-repetition-rate pulses with high-peak-powers, such as femtosecond laser amplifiers, to facilitate investigations of strong light–matter interactions and nonlinear processes at the nanoscale. PMID:27748360

The Applicability of the American College of Cardiology Appropriate Use Criteria for Myocardial Perfusion Scintigraphy in Australia.

PubMed

Chow, Chee Loong; Ponnuthurai, Francis A; Allman, Kevin C; van Gaal, William

2018-04-01

The American College of Cardiology (ACC) Appropriate Use Criteria (AUC) for radionuclide myocardial perfusion scans (MPS) was developed to promote its rational use in the assessment of stable ischaemic heart disease (IHD). We sought to validate the applicability of this document in the Australian context. 1009 consecutive patients who underwent MPS were retrospectively audited at a single major metropolitan hospital in Victoria, Australia. Appropriateness was assigned based on the 2013 ACC AUC, and common indications and predictors of positive scan results were examined. The AUC was successfully applied (99.1%) retrospectively. A large proportion of scans were deemed appropriate (82.7%), whilst 7.8% were maybe appropriate. Positive detection rates in these groups were 17.0% and 17.9% respectively. Eighteen patients (1.8%) were unclassifiable, but had a detection rate of 44.4%. Positive predictors of an abnormal MPS result included prior history of coronary artery disease, typical angina, and following the conservative management of an acute coronary syndrome. Scans that were rarely appropriate had a detection rate of 0%. The retrospective application of the 2013 ACC AUC is feasible. Whilst the majority of the scans were appropriate, a group of unclassifiable patients was observed to have a high detection rate. Scans that were rarely appropriate could potentially be rationalised to reduce radiation risk. Copyright © 2017 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

High-stroke silicon-on-insulator MEMS nanopositioner: Control design for non-raster scan atomic force microscopy

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

Maroufi, Mohammad, E-mail: Mohammad.Maroufi@uon.edu.au; Fowler, Anthony G., E-mail: Anthony.Fowler@uon.edu.au; Bazaei, Ali, E-mail: Ali.Bazaei@newcastle.edu.au

A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 μm. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics ofmore » the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 μm × 20 μm. The maximum scan rate demonstrated is 1 kHz.« less

Electronic cameras for low-light microscopy.

PubMed

Rasnik, Ivan; French, Todd; Jacobson, Ken; Berland, Keith

2013-01-01

This chapter introduces to electronic cameras, discusses the various parameters considered for evaluating their performance, and describes some of the key features of different camera formats. The chapter also presents the basic understanding of functioning of the electronic cameras and how these properties can be exploited to optimize image quality under low-light conditions. Although there are many types of cameras available for microscopy, the most reliable type is the charge-coupled device (CCD) camera, which remains preferred for high-performance systems. If time resolution and frame rate are of no concern, slow-scan CCDs certainly offer the best available performance, both in terms of the signal-to-noise ratio and their spatial resolution. Slow-scan cameras are thus the first choice for experiments using fixed specimens such as measurements using immune fluorescence and fluorescence in situ hybridization. However, if video rate imaging is required, one need not evaluate slow-scan CCD cameras. A very basic video CCD may suffice if samples are heavily labeled or are not perturbed by high intensity illumination. When video rate imaging is required for very dim specimens, the electron multiplying CCD camera is probably the most appropriate at this technological stage. Intensified CCDs provide a unique tool for applications in which high-speed gating is required. The variable integration time video cameras are very attractive options if one needs to acquire images at video rate acquisition, as well as with longer integration times for less bright samples. This flexibility can facilitate many diverse applications with highly varied light levels. Copyright © 2007 Elsevier Inc. All rights reserved.

Microlaser-based displays

NASA Astrophysics Data System (ADS)

Bergstedt, Robert; Fink, Charles G.; Flint, Graham W.; Hargis, David E.; Peppler, Philipp W.

1997-07-01

Laser Power Corporation has developed a new type of projection display, based upon microlaser technology and a novel scan architecture, which provides the foundation for bright, extremely high resolution images. A review of projection technologies is presented along with the limitations of each and the difficulties they experience in trying to generate high resolution imagery. The design of the microlaser based projector is discussed along with the advantage of this technology. High power red, green, and blue microlasers have been designed and developed specifically for use in projection displays. These sources, in combination with high resolution, high contrast modulator, produce a 24 bit color gamut, capable of supporting the full range of real world colors. The new scan architecture, which reduces the modulation rate and scan speeds required, is described. This scan architecture, along with the inherent brightness of the laser provides the fundamentals necessary to produce a 5120 by 4096 resolution display. The brightness and color uniformity of the display is excellent, allowing for tiling of the displays with far fewer artifacts than those in a traditionally tiled display. Applications for the display include simulators, command and control centers, and electronic cinema.

Porous MoO2 nanowires as stable and high-rate negative electrodes for electrochemical capacitors.

PubMed

Zheng, Dezhou; Feng, Haobin; Zhang, Xiyue; He, Xinjun; Yu, Minghao; Lu, Xihong; Tong, Yexiang

2017-04-04

Free-standing porous MoO 2 nanowires with extraordinary capacitive performance are developed as high-performance electrodes for electrochemical capacitors. The as-obtained MoO 2 electrode exhibits a remarkable capacitance of 424.4 mF cm -2 with excellent electrochemical durability (no capacitance decay after 10 000 cycles at various scan rates).

Optical monitoring of neuronal activity at high frame rate with a digital random-access multiphoton (RAMP) microscope.

PubMed

Otsu, Yo; Bormuth, Volker; Wong, Jerome; Mathieu, Benjamin; Dugué, Guillaume P; Feltz, Anne; Dieudonné, Stéphane

2008-08-30

Two-photon microscopy offers the promise of monitoring brain activity at multiple locations within intact tissue. However, serial sampling of voxels has been difficult to reconcile with millisecond timescales characteristic of neuronal activity. This is due to the conflicting constraints of scanning speed and signal amplitude. The recent use of acousto-optic deflector scanning to implement random-access multiphoton microscopy (RAMP) potentially allows to preserve long illumination dwell times while sampling multiple points-of-interest at high rates. However, the real-life abilities of RAMP microscopy regarding sensitivity and phototoxicity issues, which have so far impeded prolonged optical recordings at high frame rates, have not been assessed. Here, we describe the design, implementation and characterisation of an optimised RAMP microscope. We demonstrate the application of the microscope by monitoring calcium transients in Purkinje cells and cortical pyramidal cell dendrites and spines. We quantify the illumination constraints imposed by phototoxicity and show that stable continuous high-rate recordings can be obtained. During these recordings the fluorescence signal is large enough to detect spikes with a temporal resolution limited only by the calcium dye dynamics, improving upon previous techniques by at least an order of magnitude.

Sensor for In-Motion Continuous 3D Shape Measurement Based on Dual Line-Scan Cameras

PubMed Central

Sun, Bo; Zhu, Jigui; Yang, Linghui; Yang, Shourui; Guo, Yin

2016-01-01

The acquisition of three-dimensional surface data plays an increasingly important role in the industrial sector. Numerous 3D shape measurement techniques have been developed. However, there are still limitations and challenges in fast measurement of large-scale objects or high-speed moving objects. The innovative line scan technology opens up new potentialities owing to the ultra-high resolution and line rate. To this end, a sensor for in-motion continuous 3D shape measurement based on dual line-scan cameras is presented. In this paper, the principle and structure of the sensor are investigated. The image matching strategy is addressed and the matching error is analyzed. The sensor has been verified by experiments and high-quality results are obtained. PMID:27869731

Selective laser ablation of carious lesions using simultaneous scanned near-IR diode and CO2 lasers

NASA Astrophysics Data System (ADS)

Chan, Kenneth H.; Fried, Daniel

2017-02-01

Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

Selective Laser Ablation of Carious Lesions using Simultaneous Scanned Near-IR Diode and CO2 Lasers.

PubMed

Chan, Kenneth H; Fried, Daniel

2017-01-28

Previous studies have established that carious lesions can be imaged with high contrast using near-IR wavelengths coincident with high water absorption, namely 1450-nm, without the interference of stains. It has been demonstrated that computer-controlled laser scanning systems utilizing IR lasers operating at high pulse repetition rates can be used for serial imaging and selective removal of caries lesions. In this study, a point-to-point scanning system was developed integrating a 1450-nm diode laser with the CO 2 ablation laser. This approach is advantageous since it does not require an expensive near-IR camera. In this pilot study, we demonstrate the feasibility of a combined NIR and IR laser system for the selective removal of carious lesions.

Direct-detected rapid-scan EPR at 250 MHz

NASA Astrophysics Data System (ADS)

Stoner, James W.; Szymanski, Dennis; Eaton, Sandra S.; Quine, Richard W.; Rinard, George A.; Eaton, Gareth R.

2004-09-01

EPR spectra at 250 MHz for a single crystal of lithium phthalocyanine (LiPc) in the absence of oxygen and for a deoxygenated aqueous solution of a Nycomed triarylmethyl (trityl-CD 3) radical were obtained at scan rates between 1.3 × 10 3 and 3.4 × 10 5 G/s. These scan rates are rapid relative to the reciprocals of the electron spin relaxation times (LiPc: T1=3.5 μs and T2=2.5 μs; trityl: T1=12 μs and T2=11.5 μs) and cause characteristic oscillations in the direct-detected absorption spectra. For a given scan rate, shorter values of T2 and increased inhomogeneous broadening cause less deep oscillations that damp out more quickly than for longer T2. There is excellent agreement between experimental and calculated lineshapes and signal amplitudes as a function of radiofrequency magnetic field ( B1) and scan rate. When B1 is adjusted for maximum signal amplitude as a function of scan rate, signal intensity for constant number of scans is enhanced by up to a factor of three relative to slow scans. The number of scans that can be averaged in a defined period of time is proportional to the scan rate, which further enhances signal amplitude per unit time. Longer relaxation times cause the maximum signal intensity to occur at slower scan rates. These experiments provide the first systematic characterization of direct-detected rapid-scan EPR signals.

High resolution light-sheet based high-throughput imaging cytometry system enables visualization of intra-cellular organelles

NASA Astrophysics Data System (ADS)

Regmi, Raju; Mohan, Kavya; Mondal, Partha Pratim

2014-09-01

Visualization of intracellular organelles is achieved using a newly developed high throughput imaging cytometry system. This system interrogates the microfluidic channel using a sheet of light rather than the existing point-based scanning techniques. The advantages of the developed system are many, including, single-shot scanning of specimens flowing through the microfluidic channel at flow rate ranging from micro- to nano- lit./min. Moreover, this opens-up in-vivo imaging of sub-cellular structures and simultaneous cell counting in an imaging cytometry system. We recorded a maximum count of 2400 cells/min at a flow-rate of 700 nl/min, and simultaneous visualization of fluorescently-labeled mitochondrial network in HeLa cells during flow. The developed imaging cytometry system may find immediate application in biotechnology, fluorescence microscopy and nano-medicine.

Electrochemical wall shear rate microscopy of collapsing bubbles

NASA Astrophysics Data System (ADS)

Reuter, Fabian; Mettin, Robert

2018-06-01

An electrochemical high-speed wall shear raster microscope is presented. It involves chronoamperometric measurements on a microelectrode that is flush-mounted in a submerged test specimen. Wall shear rates are derived from the measured microelectrode signal by numerically solving a convection-diffusion equation with an optimization approach. This way, the unsteady wall shear rates from the collapse of a laser pulse seeded cavitation bubble close to a substrate are measured. By planar scanning, they are resolved in high spatial resolution. The wall shear rates are related to the bubble dynamics via synchronized high-speed imaging of the bubble shape.

Using ultrahigh sensitive optical microangiography to achieve comprehensive depth resolved microvasculature mapping for human retina

NASA Astrophysics Data System (ADS)

An, Lin; Shen, Tueng T.; Wang, Ruikang K.

2011-10-01

This paper presents comprehensive and depth-resolved retinal microvasculature images within human retina achieved by a newly developed ultrahigh sensitive optical microangiography (UHS-OMAG) system. Due to its high flow sensitivity, UHS-OMAG is much more sensitive to tissue motion due to the involuntary movement of the human eye and head compared to the traditional OMAG system. To mitigate these motion artifacts on final imaging results, we propose a new phase compensation algorithm in which the traditional phase-compensation algorithm is repeatedly used to efficiently minimize the motion artifacts. Comparatively, this new algorithm demonstrates at least 8 to 25 times higher motion tolerability, critical for the UHS-OMAG system to achieve retinal microvasculature images with high quality. Furthermore, the new UHS-OMAG system employs a high speed line scan CMOS camera (240 kHz A-line scan rate) to capture 500 A-lines for one B-frame at a 400 Hz frame rate. With this system, we performed a series of in vivo experiments to visualize the retinal microvasculature in humans. Two featured imaging protocols are utilized. The first is of the low lateral resolution (16 μm) and a wide field of view (4 × 3 mm2 with single scan and 7 × 8 mm2 for multiple scans), while the second is of the high lateral resolution (5 μm) and a narrow field of view (1.5 × 1.2 mm2 with single scan). The great imaging performance delivered by our system suggests that UHS-OMAG can be a promising noninvasive alternative to the current clinical retinal microvasculature imaging techniques for the diagnosis of eye diseases with significant vascular involvement, such as diabetic retinopathy and age-related macular degeneration.

Three-Dimensional Bi-Continuous Nanoporous Gold/Nickel Foam Supported MnO2 for High Performance Supercapacitors.

PubMed

Zhao, Jie; Zou, Xilai; Sun, Peng; Cui, Guofeng

2017-12-19

A three-dimensional bi-continuous nanoporous gold (NPG)/nickel foam is developed though the electrodeposition of a gold-tin alloy on Ni foam and subsequent chemical dealloying of tin. The newly-designed 3D metal structure is used to anchor MnO 2 nanosheets for high-performance supercapacitors. The formed ternary composite electrodes exhibit significantly-enhanced capacitance performance, rate capability, and excellent cycling stability. A specific capacitance of 442 Fg -1 is achieved at a scan rate of 5 mV s -1 and a relatively high mass loading of 865 μg cm -2 . After 2500 cycles, only a 1% decay is found at a scan rate of 50 mV s -1 . A high power density of 3513 W kg -1 and an energy density of 25.73 Wh kg -1 are realized for potential energy storage devices. The results demonstrate that the NPG/nickel foam hybrid structure significantly improves the dispersibility of MnO 2 and makes it promising for practical energy storage applications.

Extended dynamic range of Doppler OCT by application of a new method to high density B-scans using a MHz FDML swept laser source (Conference Presentation)

NASA Astrophysics Data System (ADS)

Elahi, Sahar; Thrane, Lars; Rollins, Andrew M.; Jenkins, Michael W.

2017-02-01

The limited dynamic range of optical coherence tomography (OCT) Doppler velocity measurements makes it difficult to conduct experiments on samples requiring a large dynamic range without phase wrapping at high velocities or loss of sensitivity at slow velocities. Hemodynamics and wall motion undergo significant increases in velocity as the embryonic heart develops. Experimental studies indicate that altered hemodynamics in early-stage embryonic hearts can lead to congenital heart diseases (CHDs), motivating close monitoring of blood flow over several stages of development. We have built a high-speed OCT system using an FDML laser (Optores GmbH, Germany) at a sweep rate of 1.68 MHz (axial resolution - 12 μm, sensitivity - 105 dB, phase stability - 17 mrad). The speed of this OCT system allows us to acquire high-density B-scans to obtain an extended velocity dynamic range without sacrificing the frame rate (100 Hz). The extended dynamic range within a frame is achieved by varying the A-scan interval at which the phase difference is found, enabling detection of velocities ranging from tens of microns per second to hundreds of millimeters per second. The extra lines in a frame can also be utilized to improve the structural and Doppler images via complex averaging. In structural images where the presence of blood causes additional scattering, complex averaging helps retrieve features located deeper in the tissue. Moreover, high-density frames can be registered to 4D volumes to determine the orthogonal direction of flow for calculating shear stress as well as estimating the cardiac output. In conclusion, high density B-scans acquired by our high-speed OCT system enable image enhancement and direct measurement of biological parameters in cohort studies.

A stochastic framework for spot-scanning particle therapy.

PubMed

Robini, Marc; Yuemin Zhu; Wanyu Liu; Magnin, Isabelle

2016-08-01

In spot-scanning particle therapy, inverse treatment planning is usually limited to finding the optimal beam fluences given the beam trajectories and energies. We address the much more challenging problem of jointly optimizing the beam fluences, trajectories and energies. For this purpose, we design a simulated annealing algorithm with an exploration mechanism that balances the conflicting demands of a small mixing time at high temperatures and a reasonable acceptance rate at low temperatures. Numerical experiments substantiate the relevance of our approach and open new horizons to spot-scanning particle therapy.

Solid state optical microscope

DOEpatents

Young, I.T.

1983-08-09

A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal. 2 figs.

Solid state optical microscope

DOEpatents

Young, Ian T.

1983-01-01

A solid state optical microscope wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. A galvanometer scanning mirror, for scanning in one of two orthogonal directions is provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.

Utility of High Throughput Screening Techniques to Predict Stability of Monoclonal Antibody Formulations During Early Stage Development.

PubMed

Goldberg, Deborah S; Lewus, Rachael A; Esfandiary, Reza; Farkas, David C; Mody, Neil; Day, Katrina J; Mallik, Priyanka; Tracka, Malgorzata B; Sealey, Smita K; Samra, Hardeep S

2017-08-01

Selecting optimal formulation conditions for monoclonal antibodies for first time in human clinical trials is challenging due to short timelines and reliance on predictive assays to ensure product quality and adequate long-term stability. Accelerated stability studies are considered to be the gold standard for excipient screening, but they are relatively low throughput and time consuming. High throughput screening (HTS) techniques allow for large amounts of data to be collected quickly and easily, and can be used to screen solution conditions for early formulation development. The utility of using accelerated stability compared to HTS techniques (differential scanning light scattering and differential scanning fluorescence) for early formulation screening was evaluated along with the impact of excipients of various types on aggregation of monoclonal antibodies from multiple IgG subtypes. The excipient rank order using quantitative HTS measures was found to correlate with accelerated stability aggregation rate ranking for only 33% (by differential scanning fluorescence) to 42% (by differential scanning light scattering) of the antibodies tested, due to the high intrinsic stability and minimal impact of excipients on aggregation rates and HTS data. Also explored was a case study of employing a platform formulation instead of broader formulation screening for early formulation development. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

High-resolution whole-brain DCE-MRI using constrained reconstruction: Prospective clinical evaluation in brain tumor patients.

PubMed

Guo, Yi; Lebel, R Marc; Zhu, Yinghua; Lingala, Sajan Goud; Shiroishi, Mark S; Law, Meng; Nayak, Krishna

2016-05-01

To clinically evaluate a highly accelerated T1-weighted dynamic contrast-enhanced (DCE) MRI technique that provides high spatial resolution and whole-brain coverage via undersampling and constrained reconstruction with multiple sparsity constraints. Conventional (rate-2 SENSE) and experimental DCE-MRI (rate-30) scans were performed 20 minutes apart in 15 brain tumor patients. The conventional clinical DCE-MRI had voxel dimensions 0.9 × 1.3 × 7.0 mm(3), FOV 22 × 22 × 4.2 cm(3), and the experimental DCE-MRI had voxel dimensions 0.9 × 0.9 × 1.9 mm(3), and broader coverage 22 × 22 × 19 cm(3). Temporal resolution was 5 s for both protocols. Time-resolved images and blood-brain barrier permeability maps were qualitatively evaluated by two radiologists. The experimental DCE-MRI scans showed no loss of qualitative information in any of the cases, while achieving substantially higher spatial resolution and whole-brain spatial coverage. Average qualitative scores (from 0 to 3) were 2.1 for the experimental scans and 1.1 for the conventional clinical scans. The proposed DCE-MRI approach provides clinically superior image quality with higher spatial resolution and coverage than currently available approaches. These advantages may allow comprehensive permeability mapping in the brain, which is especially valuable in the setting of large lesions or multiple lesions spread throughout the brain.

Modelling rating curves using remotely sensed LiDAR data

USGS Publications Warehouse

Nathanson, Marcus; Kean, Jason W.; Grabs, Thomas J.; Seibert, Jan; Laudon, Hjalmar; Lyon, Steve W.

2012-01-01

Accurate stream discharge measurements are important for many hydrological studies. In remote locations, however, it is often difficult to obtain stream flow information because of the difficulty in making the discharge measurements necessary to define stage-discharge relationships (rating curves). This study investigates the feasibility of defining rating curves by using a fluid mechanics-based model constrained with topographic data from an airborne LiDAR scanning. The study was carried out for an 8m-wide channel in the boreal landscape of northern Sweden. LiDAR data were used to define channel geometry above a low flow water surface along the 90-m surveyed reach. The channel topography below the water surface was estimated using the simple assumption of a flat streambed. The roughness for the modelled reach was back calculated from a single measurment of discharge. The topographic and roughness information was then used to model a rating curve. To isolate the potential influence of the flat bed assumption, a 'hybrid model' rating curve was developed on the basis of data combined from the LiDAR scan and a detailed ground survey. Whereas this hybrid model rating curve was in agreement with the direct measurements of discharge, the LiDAR model rating curve was equally in agreement with the medium and high flow measurements based on confidence intervals calculated from the direct measurements. The discrepancy between the LiDAR model rating curve and the low flow measurements was likely due to reduced roughness associated with unresolved submerged bed topography. Scanning during periods of low flow can help minimize this deficiency. These results suggest that combined ground surveys and LiDAR scans or multifrequency LiDAR scans that see 'below' the water surface (bathymetric LiDAR) could be useful in generating data needed to run such a fluid mechanics-based model. This opens a realm of possibility to remotely sense and monitor stream flows in channels in remote locations.

High-throughput microfluidic line scan imaging for cytological characterization

NASA Astrophysics Data System (ADS)

Hutcheson, Joshua A.; Powless, Amy J.; Majid, Aneeka A.; Claycomb, Adair; Fritsch, Ingrid; Balachandran, Kartik; Muldoon, Timothy J.

2015-03-01

Imaging cells in a microfluidic chamber with an area scan camera is difficult due to motion blur and data loss during frame readout causing discontinuity of data acquisition as cells move at relatively high speeds through the chamber. We have developed a method to continuously acquire high-resolution images of cells in motion through a microfluidics chamber using a high-speed line scan camera. The sensor acquires images in a line-by-line fashion in order to continuously image moving objects without motion blur. The optical setup comprises an epi-illuminated microscope with a 40X oil immersion, 1.4 NA objective and a 150 mm tube lens focused on a microfluidic channel. Samples containing suspended cells fluorescently stained with 0.01% (w/v) proflavine in saline are introduced into the microfluidics chamber via a syringe pump; illumination is provided by a blue LED (455 nm). Images were taken of samples at the focal plane using an ELiiXA+ 8k/4k monochrome line-scan camera at a line rate of up to 40 kHz. The system's line rate and fluid velocity are tightly controlled to reduce image distortion and are validated using fluorescent microspheres. Image acquisition was controlled via MATLAB's Image Acquisition toolbox. Data sets comprise discrete images of every detectable cell which may be subsequently mined for morphological statistics and definable features by a custom texture analysis algorithm. This high-throughput screening method, comparable to cell counting by flow cytometry, provided efficient examination including counting, classification, and differentiation of saliva, blood, and cultured human cancer cells.

Two-photon imaging of spatially extended neuronal network dynamics with high temporal resolution.

PubMed

Lillis, Kyle P; Eng, Alfred; White, John A; Mertz, Jerome

2008-07-30

We describe a simple two-photon fluorescence imaging strategy, called targeted path scanning (TPS), to monitor the dynamics of spatially extended neuronal networks with high spatiotemporal resolution. Our strategy combines the advantages of mirror-based scanning, minimized dead time, ease of implementation, and compatibility with high-resolution low-magnification objectives. To demonstrate the performance of TPS, we monitor the calcium dynamics distributed across an entire juvenile rat hippocampus (>1.5mm), at scan rates of 100 Hz, with single cell resolution and single action potential sensitivity. Our strategy for fast, efficient two-photon microscopy over spatially extended regions provides a particularly attractive solution for monitoring neuronal population activity in thick tissue, without sacrificing the signal-to-noise ratio or high spatial resolution associated with standard two-photon microscopy. Finally, we provide the code to make our technique generally available.

Effects of scan rate on the corrosion behavior SS 304 stainless steel in the nanofluid measured by Tafel polarization methods

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

Prajitno, Djoko Hadi

The Effects of scan rate on the Tafel polarization curve that is obtained to determine corrosion rate are conducted. The tafel polarization curves are obtained at different scan rates for Stainless Steel 304 in nanofluids contain 0.01 gpl nano particle ZrO{sub 2}. The corrosion stainless steel in nanofluid contains adm+0.01 gpl ZrO{sub 2} nanoparticles at different scan rate was performed by Tafel polarization. The results show that according corrosion potential examination of the stainless steel in nanofluid media 0.01gpl ZrO{sub 2} nanoparticle was actively corroded. The value of cathodic Tafel slope stainless steel in nanofluid at different scan rate relativelymore » unchanged after polarization testing. Mean while the value of anodic Tafel slope stainless steel in nanofluid increase at different scan rate. The results of Tafel polarization technique show that corrosion rate of stainless steel in nanofluid increase with increasing scan rate. X ray diffraction examination of stainless steel after Tafel polarization depict that γ Fe phase is major phase in the surface of alloy.« less

Sheet-scanned dual-axis confocal microscopy using Richardson-Lucy deconvolution.

PubMed

Wang, D; Meza, D; Wang, Y; Gao, L; Liu, J T C

2014-09-15

We have previously developed a line-scanned dual-axis confocal (LS-DAC) microscope with subcellular resolution suitable for high-frame-rate diagnostic imaging at shallow depths. Due to the loss of confocality along one dimension, the contrast (signal-to-background ratio) of a LS-DAC microscope is deteriorated compared to a point-scanned DAC microscope. However, by using a sCMOS camera for detection, a short oblique light-sheet is imaged at each scanned position. Therefore, by scanning the light sheet in only one dimension, a thin 3D volume is imaged. Both sequential two-dimensional deconvolution and three-dimensional deconvolution are performed on the thin image volume to improve the resolution and contrast of one en face confocal image section at the center of the volume, a technique we call sheet-scanned dual-axis confocal (SS-DAC) microscopy.

Multi-level scanning method for defect inspection

DOEpatents

Bokor, Jeffrey; Jeong, Seongtae

2002-01-01

A method for performing scanned defect inspection of a collection of contiguous areas using a specified false-alarm-rate and capture-rate within an inspection system that has characteristic seek times between inspection locations. The multi-stage method involves setting an increased false-alarm-rate for a first stage of scanning, wherein subsequent stages of scanning inspect only the detected areas of probable defects at lowered values for the false-alarm-rate. For scanning inspection operations wherein the seek time and area uncertainty is favorable, the method can substantially increase inspection throughput.

Frequency-agile, rapid scanning spectroscopy: absorption sensitivity of 2 × 10-12 cm-1 Hz-1/2 with a tunable diode laser

NASA Astrophysics Data System (ADS)

Long, D. A.; Truong, G.-W.; van Zee, R. D.; Plusquellic, D. F.; Hodges, J. T.

2014-03-01

We present ultrasensitive measurements of molecular absorption using frequency-agile rapid scanning, cavity ring-down spectroscopy with an external-cavity diode laser. A microwave source that drives an electro-optic phase modulator with a bandwidth of 20 GHz generates pairs of sidebands on the probe laser. The optical cavity provides for high sensitivity and filters the carrier and all but a single, selected sideband. Absorption spectra were acquired by stepping the tunable sideband from mode-to-mode of the ring-down cavity at a rate that was limited only by the cavity decay time. This approach allows for scanning rates of 8 kHz per cavity resonance, a minimum detectable absorption coefficient of 1.7 × 10-11 cm-1 after only 20 ms of averaging, and a noise-equivalent absorption coefficient of 1.7 × 10-12 cm-1 Hz-1/2. By comparison with cavity-enhanced laser absorption spectrometers reported in the literature, the present system is, to the best of our knowledge, among the most sensitive and has by far the highest spectrum scanning rate.

Generation of ultra high-power thermal plasma jet and its application to crystallization of amorphous silicon films

NASA Astrophysics Data System (ADS)

Nakashima, Ryosuke; Shin, Ryota; Hanafusa, Hiroaki; Higashi, Seiichiro

2017-06-01

We have successfully generated ultra high-power thermal plasma jet (Super TPJ: s-TPJ) by increasing the Ar gas supply pressure to 0.4 MPa and the flow rate to 18 L/min. DC arc discharge was stably performed under a supply power of 4.6 kW. The peak power density of s-TPJ reached 64.1 kW/cm2 and enabled us to melt and recrystallize amorphous silicon (a-Si) films on quartz substrates with a scanning speed as high as 8000 mm/s. Under ultra high-speed scanning faster than 3000 mm/s, we observed granular crystal growth (GCG) competing with conventional high-speed lateral crystallization (HSLC). When further high speed scanning was performed, we observed a significant increase in grain density, which suggests spontaneous nucleation in undercooled molten Si as the origin of GCG. When we crystallized an isolated pattern of 6 × 6 µm2 under GCG conditions, single crystalline growth was successfully achieved.

Goddard Conference on Mass Storage Systems and Technologies, volume 2

NASA Technical Reports Server (NTRS)

Kobler, Ben (Editor); Hariharan, P. C. (Editor)

1993-01-01

Papers and viewgraphs from the conference are presented. Discussion topics include the IEEE Mass Storage System Reference Model, data archiving standards, high-performance storage devices, magnetic and magneto-optic storage systems, magnetic and optical recording technologies, high-performance helical scan recording systems, and low end helical scan tape drives. Additional discussion topics addressed the evolution of the identifiable unit for processing (file, granule, data set, or some similar object) as data ingestion rates increase dramatically, and the present state of the art in mass storage technology.

Wide-field reflective scanning optical systems

NASA Technical Reports Server (NTRS)

Abel, I. R.

1973-01-01

Catoptric optical scanning system provides relatively fast line-scan rate for two-dimensional coverage. Rapid scan rates require low focal ratios between components and smallest possible masses. System is relatively free from monochromatic defects and chromatic aberrations.

A high stability and repeatability electrochemical scanning tunneling microscope.

PubMed

Xia, Zhigang; Wang, Jihao; Hou, Yubin; Lu, Qingyou

2014-12-01

We present a home built electrochemical scanning tunneling microscope (ECSTM) with very high stability and repeatability. Its coarse approach is driven by a closely stacked piezo motor of GeckoDrive type with four rigid clamping points, which enhances the rigidity, compactness, and stability greatly. It can give high clarity atomic resolution images without sound and vibration isolations. Its drifting rates in XY and Z directions in solution are as low as 84 pm/min and 59 pm/min, respectively. In addition, repeatable coarse approaches in solution within 2 mm travel distance show a lateral deviation less than 50 nm. The gas environment can be well controlled to lower the evaporation rate of the cell, thus reducing the contamination and elongating the measurement time. Atomically resolved SO4(2-) image on Au (111) work electrode is demonstrated to show the performance of the ECSTM.

Dark-count-less photon-counting x-ray computed tomography system using a YAP-MPPC detector

NASA Astrophysics Data System (ADS)

Sato, Eiichi; Sato, Yuich; Abudurexiti, Abulajiang; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2012-10-01

A high-sensitive X-ray computed tomography (CT) system is useful for decreasing absorbed dose for patients, and a dark-count-less photon-counting CT system was developed. X-ray photons are detected using a YAP(Ce) [cerium-doped yttrium aluminum perovskite] single crystal scintillator and an MPPC (multipixel photon counter). Photocurrents are amplified by a high-speed current-voltage amplifier, and smooth event pulses from an integrator are sent to a high-speed comparator. Then, logical pulses are produced from the comparator and are counted by a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The image contrast of gadolinium medium slightly fell with increase in lower-level voltage (Vl) of the comparator. The dark count rate was 0 cps, and the count rate for the CT was approximately 250 kcps.

Face and content validity of the virtual reality simulator 'ScanTrainer®'.

PubMed

Alsalamah, Amal; Campo, Rudi; Tanos, Vasilios; Grimbizis, Gregoris; Van Belle, Yves; Hood, Kerenza; Pugh, Neil; Amso, Nazar

2017-01-01

Ultrasonography is a first-line imaging in the investigation of women's irregular bleeding and other gynaecological pathologies, e.g. ovarian cysts and early pregnancy problems. However, teaching ultrasound, especially transvaginal scanning, remains a challenge for health professionals. New technology such as simulation may potentially facilitate and expedite the process of learning ultrasound. Simulation may prove to be realistic, very close to real patient scanning experience for the sonographer and objectively able to assist the development of basic skills such as image manipulation, hand-eye coordination and examination technique. The aim of this study was to determine the face and content validity of a virtual reality simulator (ScanTrainer®, MedaPhor plc, Cardiff, Wales, UK) as reflective of real transvaginal ultrasound (TVUS) scanning. A questionnaire with 14 simulator-related statements was distributed to a number of participants with differing levels of sonography experience in order to determine the level of agreement between the use of the simulator in training and real practice. There were 36 participants: novices ( n  = 25) and experts ( n  = 11) who rated the simulator. Median scores of face validity statements between experts and non-experts using a 10-point visual analogue scale (VAS) ratings ranged between 7.5 and 9.0 ( p  > 0.05) indicated a high level of agreement. Experts' median scores of content validity statements ranged from 8.4 to 9.0. The findings confirm that the simulator has the feel and look of real-time scanning with high face validity. Similarly, its tutorial structures and learning steps confirm the content validity.

Morphology and crystallinity-controlled synthesis of manganese cobalt oxide/manganese dioxides hierarchical nanostructures for high-performance supercapacitors

NASA Astrophysics Data System (ADS)

Li, Fei; Li, Gang; Chen, Hao; Jia, Jia Qi; Dong, Fan; Hu, Yao Bo; Shang, Zheng Guo; Zhang, Yu Xin

2015-11-01

We demonstrate a novel preparative strategy for the well-controlled MnCo2O4.5@MnO2 hierarchical nanostructures. Both δ-MnO2 nanosheets and α-MnO2 nanorods can uniformly decorate the surface of MnCo2O4.5 nanowires to form core-shell heterostructures. Detailed electrochemical characterization reveals that MnCo2O4.5@δ-MnO2 pattern exhibits not only high specific capacitance of 357.5 F g-1 at a scan rate of 0.5 A g-1, but also good cycle stability (97% capacitance retention after 1000 cycles at a scan rate of 5 A g-1), which make it have a promising application as a supercapacitor electrode material.

Melting of α'- and α-crystals of poly(lactic acid)

NASA Astrophysics Data System (ADS)

Di Lorenzo, Maria Laura; Androsch, René

2016-05-01

The influence of chain structure on thermal stability of α'-crystals of poly(lactic acid) (PLA) with high L-lactic acid content (96-100 %) is detailed in this contribution. α'-crystals of PLA grow at temperatures below 120 °C, and spontaneously transform into stable α-modification during heating. Using conventional differential scanning calorimetry (DSC) and fast scanning chip calorimetry (FSC), a wide range of scanning rates, between about 10-1 and 102 K s-1 could be tested. It was found that reorganization of disordered α'-crystals into stable α-crystals can be suppressed by fast heating. The critical heating rate needed to completely melt α'-crystals and to avoid formation of α-crystals on continuation of heating varies with the chain composition, and decreases upon increase of the D-lactic acid content in the PLA chain.

Table screen 360-degree holographic display using circular viewing-zone scanning.

PubMed

Inoue, Tatsuaki; Takaki, Yasuhiro

2015-03-09

A table screen 360-degree holographic display is proposed, with an increased screen size, having an expanded viewing zone over all horizontal directions around the table screen. It consists of a microelectromechanical systems spatial light modulator (MEMS SLM), a magnifying imaging system, and a rotating screen. The MEMS SLM generates hologram patterns at a high frame rate, the magnifying imaging system increases the screen of the MEMS SLM, and the reduced viewing zones are scanned circularly by the rotating screen. The viewing zones are localized to practically realize wavefront reconstruction. An experimental system has been constructed. The generation of 360-degree three-dimensional (3D) images was achieved by scanning 800 reduced and localized viewing zones circularly. The table screen had a diameter of 100 mm, and the frame rate of 3D image generation was 28.4 Hz.

[Study on absorbing volatile oil with mesoporous carbon].

PubMed

Yan, Hong-mei; Jia, Xiao-bin; Zhang, Zhen-hai; Sun, E; Yang Nan

2014-11-01

Clove oil and turmeric oil were absorbed by mesoporous carbon. The absorption ratio of mesoporous carbon to volatile oil was optimized with the eugenol yield and curcumol yield as criteria Curing powder was characterized by scanning electron microscopy (SEM) and differential scanning calorietry (DSC). The effects of mesoporous carbon on dissolution in vitro and thermal stability of active components were studied. They reached high adsorption rate when the absorption ratio of mesoporous carbon to volatile oil was 1:1. When volatile oil was absorbed, dissolution rate of active components had a little improvement and their thermal stability improved after volatile oil was absorbed by the loss rate decreasing more than 50%. Absorbing herbal volatile oil with mesoporous carbon deserves further studying.

Enhanced capture rate for haze defects in production wafer inspection

NASA Astrophysics Data System (ADS)

Auerbach, Ditza; Shulman, Adi; Rozentsvige, Moshe

2010-03-01

Photomask degradation via haze defect formation is an increasing troublesome yield problem in the semiconductor fab. Wafer inspection is often utilized to detect haze defects due to the fact that it can be a bi-product of process control wafer inspection; furthermore, the detection of the haze on the wafer is effectively enhanced due to the multitude of distinct fields being scanned. In this paper, we demonstrate a novel application for enhancing the wafer inspection tool's sensitivity to haze defects even further. In particular, we present results of bright field wafer inspection using the on several photo layers suffering from haze defects. One way in which the enhanced sensitivity can be achieved in inspection tools is by using a double scan of the wafer: one regular scan with the normal recipe and another high sensitivity scan from which only the repeater defects are extracted (the non-repeater defects consist largely of noise which is difficult to filter). Our solution essentially combines the double scan into a single high sensitivity scan whose processing is carried out along two parallel routes (see Fig. 1). Along one route, potential defects follow the standard recipe thresholds to produce a defect map at the nominal sensitivity. Along the alternate route, potential defects are used to extract only field repeater defects which are identified using an optimal repeater algorithm that eliminates "false repeaters". At the end of the scan, the two defect maps are merged into one with optical scan images available for all the merged defects. It is important to note, that there is no throughput hit; in addition, the repeater sensitivity is increased relative to a double scan, due to a novel runtime algorithm implementation whose memory requirements are minimized, thus enabling to search a much larger number of potential defects for repeaters. We evaluated the new application on photo wafers which consisted of both random and haze defects. The evaluation procedure involved scanning with three different recipe types: Standard Inspection: Nominal recipe with a low false alarm rate was used to scan the wafer and repeaters were extracted from the final defect map. Haze Monitoring Application: Recipe sensitivity was enhanced and run on a single field column from which on repeating defects were extracted. Enhanced Repeater Extractor: Defect processing included the two parallel routes: a nominal recipe for the random defects and the new high sensitive repeater extractor algorithm. The results showed that the new application (recipe #3) had the highest capture rate on haze defects and detected new repeater defects not found in the first two recipes. In addition, the recipe was much simpler to setup since repeaters are filtered separately from random defects. We expect that in the future, with the advent of mask-less lithography and EUV lithography, the monitoring of field and die repeating defects on the wafer will become a necessity for process control in the semiconductor fab.

Estimating the exceedance probability of rain rate by logistic regression

NASA Technical Reports Server (NTRS)

Chiu, Long S.; Kedem, Benjamin

1990-01-01

Recent studies have shown that the fraction of an area with rain intensity above a fixed threshold is highly correlated with the area-averaged rain rate. To estimate the fractional rainy area, a logistic regression model, which estimates the conditional probability that rain rate over an area exceeds a fixed threshold given the values of related covariates, is developed. The problem of dependency in the data in the estimation procedure is bypassed by the method of partial likelihood. Analyses of simulated scanning multichannel microwave radiometer and observed electrically scanning microwave radiometer data during the Global Atlantic Tropical Experiment period show that the use of logistic regression in pixel classification is superior to multiple regression in predicting whether rain rate at each pixel exceeds a given threshold, even in the presence of noisy data. The potential of the logistic regression technique in satellite rain rate estimation is discussed.

Corrosion Performance of High Damping Alloys in 3.5% Sodium Chloride Environment.

DTIC Science & Technology

1987-09-01

Electrochemical Technique, Sea Exposure, Scanning Electron Microscopy. 9 .,5MAZT (Continue on rvre of necessary ad 4*er.#y by boock numbver# -The... electrochemical nature of corrosion provides a means of determining an almost instantaneous corrosion rate. Corrosion rate and the nature of corrosion attack were... electrochemical nature of corrosion provides a means of determining an almost instantaneous corrosion rate. Corrosion rate and the nature of

Alpha Control - A new Concept in SPM Control

NASA Astrophysics Data System (ADS)

Spizig, P.; Sanchen, D.; Volswinkler, G.; Ibach, W.; Koenen, J.

2006-03-01

Controlling modern Scanning Probe Microscopes demands highly sophisticated electronics. While flexibility and powerful computing power is of great importance in facilitating the variety of measurement modes, extremely low noise is also a necessity. Accordingly, modern SPM Controller designs are based on digital electronics to overcome the drawbacks of analog designs. While todays SPM controllers are based on DSPs or Microprocessors and often still incorporate analog parts, we are now introducing a completely new approach: Using a Field Programmable Gate Array (FPGA) to implement the digital control tasks allows unrivalled data processing speed by computing all tasks in parallel within a single chip. Time consuming task switching between data acquisition, digital filtering, scanning and the computing of feedback signals can be completely avoided. Together with a star topology to avoid any bus limitations in accessing the variety of ADCs and DACs, this design guarantees for the first time an entirely deterministic timing capability in the nanosecond regime for all tasks. This becomes especially useful for any external experiments which must be synchronized with the scan or for high speed scans that require not only closed loop control of the scanner, but also dynamic correction of the scan movement. Delicate samples additionally benefit from extremely high sample rates, allowing highly resolved signals and low noise levels.

Hierarchical porous carbon materials prepared using nano-ZnO as a template and activation agent for ultrahigh power supercapacitors.

PubMed

Wang, Haoran; Yu, Shukai; Xu, Bin

2016-09-20

Hierarchical porous carbon materials with high surface areas and a localized graphitic structure were simply prepared from sucrose using nano-ZnO as a hard template, activation agent and graphitization catalyst simultaneously, which exhibit an outstanding high-rate performance and can endure an ultrafast scan rate of 20 V s -1 and ultrahigh current density of 1000 A g -1 .

Carbon nanotubes/cobalt sulfide composites as potential high-rate and high-efficiency supercapacitors

NASA Astrophysics Data System (ADS)

Chen, Chia-Ying; Shih, Zih-Yu; Yang, Zusing; Chang, Huan-Tsung

2012-10-01

We have prepared carbon nanotube (CNT)/cobalt sulfide (CoS) composites from cobalt nitrate, thioacetamide, and CNTs in the presence of poly(vinylpyrrolidone). CNT/CoS composites are deposited onto fluorine-doped tin oxide glass substrates and then subjected to simple annealing at 300 °C for 0.5 h to fabricate CNT/CoS electrodes. Data collected from Raman spectroscopy, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy, and d-spacing reveal the changes in the CoS structures and crystalline lattices after annealing. Cyclic voltammetry results reveal that the annealed CNT/CoS composite electrodes yield values of 2140 ± 90 and 1370 ± 50 F g-1 for specific capacitance at scan rates of 10 and 100 mV s-1, respectively. To the best of our knowledge, the annealed CNT/CoS composite electrodes provide higher specific capacitance relative to other reported ones at a scan rate of 100 mV s-1. CNT/CoS composite electrodes yield a power density of 62.4 kW kg-1 at a constant discharge current density of 217.4 A g-1. With such a high-rate capacity and power density, CNT/CoS composite supercapacitors demonstrate great potential as efficient energy storage devices.

Meditative music listening to reduce state anxiety in patients during the uptake phase before positron emission tomography (PET) scans

PubMed Central

Lee, Wen-Li; Liu, Shu-Hsin; Chang, Shu-Min

2017-01-01

Objective: This study examines the effects of listening to meditative music on state anxiety and heart rate variability (HRV) of patients during the uptake phase before positron emission tomography (PET) scans. Methods: A two-group randomized experimental design was used. Eligible patients were randomly assigned to either the experimental or control group. All patients received baseline assessments of state anxiety using Spielberger State-Trait Anxiety Inventory (STAI-S) and HRV before receiving an intravenous injection of radiopharmaceutical fluorine-18 fludeoxyglucose in the uptake room. The experimental group (n = 35) listened individually to 30 min of meditative music, integrating Chinese “Chi” and western frequency resonation in the uptake room. The control group (n = 37) lay on bed quietly for 40 min in the uptake room without music. All patients were assessed for their anxiety level and HRV again, before receiving PET scanning as post-test. Results: The results indicated that patients in the experimental group showed a significant reduction in state anxiety and heart rate, and increase on high frequency norm of HRV (p < 0.001). There was a statistically significant reduction on anxiety level (p < 0.001), heart rate (p < 0.001) and high frequency norm (p = 0.001) in the experimental group compared with those of the control group. Conclusion: Listening to meditative music as a non-invasive and cost-effective strategy can help maximize efforts to promote comfort and relaxation for patients awaiting stressful procedures, such as PET scans. Meditative music can be effective in alleviating state anxiety of patients during the uptake phase before PET scans. Advances in knowledge: The study provides scientific evidence of the effects of listening to meditative music for reducing state anxiety in patients during the uptake phase before PET scans. It may have the potential to lower the risk of unwanted false-positive fluorine-18 fludeoxyglucose uptake in normal organs and to further improve image quality and image interpretation. Listening to meditative music is a safe and inexpensive intervention which can be incorporated into routine procedures to reduce anxiety of patients undergoing PET scans. PMID:27897034

Meditative music listening to reduce state anxiety in patients during the uptake phase before positron emission tomography (PET) scans.

PubMed

Lee, Wen-Li; Sung, Huei-Chuan; Liu, Shu-Hsin; Chang, Shu-Min

2017-02-01

This study examines the effects of listening to meditative music on state anxiety and heart rate variability (HRV) of patients during the uptake phase before positron emission tomography (PET) scans. A two-group randomized experimental design was used. Eligible patients were randomly assigned to either the experimental or control group. All patients received baseline assessments of state anxiety using Spielberger State-Trait Anxiety Inventory (STAI-S) and HRV before receiving an intravenous injection of radiopharmaceutical fluorine-18 fludeoxyglucose in the uptake room. The experimental group (n = 35) listened individually to 30 min of meditative music, integrating Chinese "Chi" and western frequency resonation in the uptake room. The control group (n = 37) lay on bed quietly for 40 min in the uptake room without music. All patients were assessed for their anxiety level and HRV again, before receiving PET scanning as post-test. The results indicated that patients in the experimental group showed a significant reduction in state anxiety and heart rate, and increase on high frequency norm of HRV (p < 0.001). There was a statistically significant reduction on anxiety level (p < 0.001), heart rate (p < 0.001) and high frequency norm (p = 0.001) in the experimental group compared with those of the control group. Listening to meditative music as a non-invasive and cost-effective strategy can help maximize efforts to promote comfort and relaxation for patients awaiting stressful procedures, such as PET scans. Meditative music can be effective in alleviating state anxiety of patients during the uptake phase before PET scans. Advances in knowledge: The study provides scientific evidence of the effects of listening to meditative music for reducing state anxiety in patients during the uptake phase before PET scans. It may have the potential to lower the risk of unwanted false-positive fluorine-18 fludeoxyglucose uptake in normal organs and to further improve image quality and image interpretation. Listening to meditative music is a safe and inexpensive intervention which can be incorporated into routine procedures to reduce anxiety of patients undergoing PET scans.

Tissue ablation accelerated by peripheral scanning mode with high-intensity focused ultrasound: a study on isolated porcine liver perfusion.

PubMed

Bu, Rui; Yin, Li; Yang, Han; Wang, Qi; Wu, Feng; Zou, Jian Zhong

2013-08-01

The aims of this study were to investigate the feasibility of accelerated tissue ablation using a peripheral scanning mode with high-intensity focused ultrasound (HIFU) and to explore the effect of flow rate on total energy consumption of the target tissues. Using a model of isolated porcine liver perfusion via the portal vein and hepatic artery, we conducted a scanning protocol along the periphery of the target tissues using linear-scanned HIFU to carefully adjust the varying focal depth, generator power, scanning velocity and line-by-line interval over the entire ablation range. Porcine livers were divided into four ablation groups: group 1, n = 12, with dual-vessel perfusion; group 2, n = 11, with portal vein perfusion alone; group 3, n = 10, with hepatic artery perfusion alone; and group 4, n = 11, control group with no-flow perfusion. The samples were cut open consecutively at a thickness of 3 mm, and the actual ablation ranges were calculated along the periphery of the target tissues after triphenyl tetrazolium chloride staining. Total energy consumption was calculated as the sum of the energy requirements at various focal depths in each group. On the basis of the pre-supposed scanning protocol, the peripheral region of the target tissue formed a complete coagulation necrosis barrier in each group with varying dose combinations, and the volume of the peripheral necrotic area did not differ significantly among the four groups (p > 0.05). Furthermore, total energy consumption in each group significantly decreased with the corresponding decrease in flow rate (p < 0.01). This study revealed that the complete peripheral necrosis barrier within the target tissues can defined using linear-scanned HIFU in an isolated porcine liver perfusion model. Additionally, the flow rate in the major hepatic vessels may play an important role in the use of the peripheral ablation mode, and this novel mode of ablation may enhance the therapeutic efficacy and tolerability of the treatment of large tumors using HIFU ablation. Copyright © 2013 World Federation for Ultrasound in Medicine & Biology. Published by Elsevier Inc. All rights reserved.

High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s.

PubMed

Wieser, Wolfgang; Draxinger, Wolfgang; Klein, Thomas; Karpf, Sebastian; Pfeiffer, Tom; Huber, Robert

2014-09-01

We present a 1300 nm OCT system for volumetric real-time live OCT acquisition and visualization at 1 billion volume elements per second. All technological challenges and problems associated with such high scanning speed are discussed in detail as well as the solutions. In one configuration, the system acquires, processes and visualizes 26 volumes per second where each volume consists of 320 x 320 depth scans and each depth scan has 400 usable pixels. This is the fastest real-time OCT to date in terms of voxel rate. A 51 Hz volume rate is realized with half the frame number. In both configurations the speed can be sustained indefinitely. The OCT system uses a 1310 nm Fourier domain mode locked (FDML) laser operated at 3.2 MHz sweep rate. Data acquisition is performed with two dedicated digitizer cards, each running at 2.5 GS/s, hosted in a single desktop computer. Live real-time data processing and visualization are realized with custom developed software on an NVidia GTX 690 dual graphics processing unit (GPU) card. To evaluate potential future applications of such a system, we present volumetric videos captured at 26 and 51 Hz of planktonic crustaceans and skin.

High definition live 3D-OCT in vivo: design and evaluation of a 4D OCT engine with 1 GVoxel/s

PubMed Central

Wieser, Wolfgang; Draxinger, Wolfgang; Klein, Thomas; Karpf, Sebastian; Pfeiffer, Tom; Huber, Robert

2014-01-01

We present a 1300 nm OCT system for volumetric real-time live OCT acquisition and visualization at 1 billion volume elements per second. All technological challenges and problems associated with such high scanning speed are discussed in detail as well as the solutions. In one configuration, the system acquires, processes and visualizes 26 volumes per second where each volume consists of 320 x 320 depth scans and each depth scan has 400 usable pixels. This is the fastest real-time OCT to date in terms of voxel rate. A 51 Hz volume rate is realized with half the frame number. In both configurations the speed can be sustained indefinitely. The OCT system uses a 1310 nm Fourier domain mode locked (FDML) laser operated at 3.2 MHz sweep rate. Data acquisition is performed with two dedicated digitizer cards, each running at 2.5 GS/s, hosted in a single desktop computer. Live real-time data processing and visualization are realized with custom developed software on an NVidia GTX 690 dual graphics processing unit (GPU) card. To evaluate potential future applications of such a system, we present volumetric videos captured at 26 and 51 Hz of planktonic crustaceans and skin. PMID:25401010

A Real-Time High Performance Data Compression Technique For Space Applications

NASA Technical Reports Server (NTRS)

Yeh, Pen-Shu; Venbrux, Jack; Bhatia, Prakash; Miller, Warner H.

2000-01-01

A high performance lossy data compression technique is currently being developed for space science applications under the requirement of high-speed push-broom scanning. The technique is also error-resilient in that error propagation is contained within a few scan lines. The algorithm is based on block-transform combined with bit-plane encoding; this combination results in an embedded bit string with exactly the desirable compression rate. The lossy coder is described. The compression scheme performs well on a suite of test images typical of images from spacecraft instruments. Hardware implementations are in development; a functional chip set is expected by the end of 2001.

CT scan exposure in Spanish children and young adults by socioeconomic status: Cross-sectional analysis of cohort data.

PubMed

Bosch de Basea, Magda; Espinosa, Ana; Gil, Mariona; Figuerola, Jordi; Pardina, Marina; Vilar, José; Cardis, Elisabeth

2018-01-01

Recent publications reported that children in disadvantaged areas undergo more CT scanning than others. The present study is aimed to assess the potential differences in CT imaging by socioeconomic status (SES) in Spanish young scanned subjects and if such differences vary with different indicators or different time point SES measurements. The associations between CT scanning and SES, and between the CT scan rate per patient and SES were investigated in the Spanish EPI-CT subcohort. Various SES indicators were studied to determine whether particular SES dimensions were more closely related to the probability of undergoing one or multiple CTs. Comparisons were made with indices based on 2001 and 2011 censuses. We found evidence of socio-economic variation among young people, mainly related to autonomous communities of residence. A slightly higher rate of scans per patient of multiple body parts in the less affluent categories was observed, possibly reflecting a higher rate of accidents and violence in these groups. The number of CT scans per patient was higher both in the most affluent and the most deprived categories and somewhat lower in the intermediate groups. This relation varied with the SES indicator used, with lower CT scans per patients in categories of high unemployment and temporary work, but not depending on categories of unskilled work or illiteracy. The relationship between these indicators and number of CTs in 2011 was different than that seen with the 2001 census, with the number of CTs increasing with higher unemployment. Overall we observed some differences in the SES distribution of scanned patients by Autonomous Community in Spain. There was, however, no major differences in the frequency of CT scans per patient by SES overall, based on the 2001 census. The use of different indicators and of SES data collected at different time points led to different relations between SES and frequency of CT scans, outlining the difficulty of adequately capturing the social and economic dimensions which may affect health and health service utilisation.

CT scan exposure in Spanish children and young adults by socioeconomic status: Cross-sectional analysis of cohort data

PubMed Central

Espinosa, Ana; Gil, Mariona; Figuerola, Jordi; Pardina, Marina; Vilar, José; Cardis, Elisabeth

2018-01-01

Recent publications reported that children in disadvantaged areas undergo more CT scanning than others. The present study is aimed to assess the potential differences in CT imaging by socioeconomic status (SES) in Spanish young scanned subjects and if such differences vary with different indicators or different time point SES measurements. The associations between CT scanning and SES, and between the CT scan rate per patient and SES were investigated in the Spanish EPI-CT subcohort. Various SES indicators were studied to determine whether particular SES dimensions were more closely related to the probability of undergoing one or multiple CTs. Comparisons were made with indices based on 2001 and 2011 censuses. We found evidence of socio-economic variation among young people, mainly related to autonomous communities of residence. A slightly higher rate of scans per patient of multiple body parts in the less affluent categories was observed, possibly reflecting a higher rate of accidents and violence in these groups. The number of CT scans per patient was higher both in the most affluent and the most deprived categories and somewhat lower in the intermediate groups. This relation varied with the SES indicator used, with lower CT scans per patients in categories of high unemployment and temporary work, but not depending on categories of unskilled work or illiteracy. The relationship between these indicators and number of CTs in 2011 was different than that seen with the 2001 census, with the number of CTs increasing with higher unemployment. Overall we observed some differences in the SES distribution of scanned patients by Autonomous Community in Spain. There was, however, no major differences in the frequency of CT scans per patient by SES overall, based on the 2001 census. The use of different indicators and of SES data collected at different time points led to different relations between SES and frequency of CT scans, outlining the difficulty of adequately capturing the social and economic dimensions which may affect health and health service utilisation. PMID:29723272

Highly flexible, all solid-state micro-supercapacitors from vertically aligned carbon nanotubes.

PubMed

Hsia, Ben; Marschewski, Julian; Wang, Shuang; In, Jung Bin; Carraro, Carlo; Poulikakos, Dimos; Grigoropoulos, Costas P; Maboudian, Roya

2014-02-07

We report a highly flexible planar micro-supercapacitor with interdigitated finger electrodes of vertically aligned carbon nanotubes (VACNTs). The planar electrode structures are patterned on a thin polycarbonate substrate with a facile, maskless laser-assisted dry transfer method. Sputtered Ni is used to reduce the in-plane resistance of the VACNT electrodes. An ionogel, an ionic liquid in a semi-solid matrix, is used as an electrolyte to form a fully solid-state device. We measure a specific capacitance of 430 μF cm(-2) for a scan rate of 0.1 V s(-1) and achieve rectangular cyclic voltammograms at high scan rates of up to 100 V s(-1). Minimal change in capacitance is observed under bending. Mechanical fatigue tests with more than 1000 cycles confirm the high flexibility and durability of the novel material combination chosen for this device. Our results indicate that this scalable and facile fabrication technique shows promise for application in integrated energy storage for all solid-state flexible microdevices.

Nitrogen-doped Carbon Microfiber with Wrinkled Surface for High Performance Supercapacitors

NASA Astrophysics Data System (ADS)

Liu, Ruili; Pan, Lixia; Jiang, Jianzhong; Xi, Xin; Liu, Xiaoxue; Wu, Dongqing

2016-02-01

In this work, nitrogen-doped carbon microfiber (NCMF) is fabricated via a facile co-assembly of natural silk and graphene oxide (GO) and the following thermal treatment. The amphiphilic nature of GO endows NCMF a crumpled surface with a high surface area of 115 m2 g-1. As the binder-free electrode in electrical double-layer capacitors, NCMF shows an excellent capacitance of 196 F g-1 at scan rate of 5 mV s-1, which is almost four times higher than that of the pristine CMF from silk (55 F g-1). Additionally, the capacitance of NCMF can be kept around 92 F g-1 at a high scan rate of 300 mV s-1 even after 10000 cycles. More importantly, a high energy density (≈22.7 μW h cm-2) and power density (≈10.26 mW cm-2) are achieved by the all-solid-state supercapacitor based on NCMF.

High temporal and spatial resolution studies of bone cells using real-time confocal reflection microscopy.

PubMed

Boyde, A; Vesely, P; Gray, C; Jones, S J

1994-01-01

Chick and rat bone-derived cells were mounted in sealed coverslip-covered chambers; individual osteoclasts (but also osteoblasts) were selected and studied at 37 degrees C using three different types of high-speed scanning confocal microscopes: (1) A Noran Tandem Scanning Microscope (TSM) was used with a low light level, cooled CCD camera for image transfer to a Noran TN8502 frame store-based image analysing computer to make time lapse movie sequences using 0.1 s exposure periods, thus losing some of the advantage of the high frame rate of the TSM. Rapid focus adjustment using computer controlled piezo drivers permitted two or more focus planes to be imaged sequentially: thus (with additional light-source shuttering) the reflection confocal image could be alternated with the phase contrast image at a different focus. Individual cells were followed for up to 5 days, suggesting no significant irradiation problem. (2) Exceptional temporal and spatial resolution is available in video rate laser confocal scanning microscopes (VRCSLMs). We used the Noran Odyssey unitary beam VRCSLM with an argon ion laser at 488 nm and acousto-optic deflection (AOD) on the line axis: this instrument is truly and adjustably confocal in the reflection mode. (3) We also used the Lasertec 1LM11 line scan instrument, with an He-Ne laser at 633 nm, and AOD for the frame scan. We discuss the technical problems and merits of the different approaches. The VRCSLMs documented rapid, real-time oscillatory motion: all the methods used show rapid net movement of organelles within bone cells. The interference reflection mode gives particularly strong contrasts in confocal instruments. Phase contrast and other interference methods used in the microscopy of living cells can be used simultaneously in the TSM.

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates.

PubMed

Zhang, Hao; Li, Xianqi; Chen, Yunmei; Park, Jewook; Li, An-Ping; Zhang, X-G

2017-01-01

We present an image postprocessing framework for Scanning Tunneling Microscope (STM) to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a "rubber band" model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA). The numerical results on measurement from copper(111) surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data.

High speed inscription of uniform, large-area laser-induced periodic surface structures in Cr films using a high repetition rate fs laser.

PubMed

Ruiz de la Cruz, A; Lahoz, R; Siegel, J; de la Fuente, G F; Solis, J

2014-04-15

We report on the fabrication of laser-induced periodic surface structures in Cr films upon high repetition rate fs laser irradiation (up to 1 MHz, 500 fs, 1030 nm), employing beam scanning. Highly regular large-area (9  cm2) gratings with a relative diffraction efficiency of 42% can be produced within less than 6 min. The ripple period at moderate and high fluences is 0.9 μm, with a small period of 0.5 μm appearing at lower energies. The role of the irradiation parameters on the characteristics of the laser-induced periodic surface structures (LIPSS) is studied and discussed in the frame of the models presently used. We have identified the polarization vector orientation with respect to the scan direction as a key parameter for the fabrication of high-quality, large-area LIPSS, which, for perpendicular orientation, allows the coherent extension of the sub-wavelength structure over macroscopic distances. The processing strategy is robust in terms of broad parameter windows and applicable to other materials featuring LIPSS.

High-resolution whole-brain DCE-MRI using constrained reconstruction: Prospective clinical evaluation in brain tumor patients

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

Guo, Yi, E-mail: yiguo@usc.edu; Zhu, Yinghua; Lingala, Sajan Goud

Purpose: To clinically evaluate a highly accelerated T1-weighted dynamic contrast-enhanced (DCE) MRI technique that provides high spatial resolution and whole-brain coverage via undersampling and constrained reconstruction with multiple sparsity constraints. Methods: Conventional (rate-2 SENSE) and experimental DCE-MRI (rate-30) scans were performed 20 minutes apart in 15 brain tumor patients. The conventional clinical DCE-MRI had voxel dimensions 0.9 × 1.3 × 7.0 mm{sup 3}, FOV 22 × 22 × 4.2 cm{sup 3}, and the experimental DCE-MRI had voxel dimensions 0.9 × 0.9 × 1.9 mm{sup 3}, and broader coverage 22 × 22 × 19 cm{sup 3}. Temporal resolution was 5 smore » for both protocols. Time-resolved images and blood–brain barrier permeability maps were qualitatively evaluated by two radiologists. Results: The experimental DCE-MRI scans showed no loss of qualitative information in any of the cases, while achieving substantially higher spatial resolution and whole-brain spatial coverage. Average qualitative scores (from 0 to 3) were 2.1 for the experimental scans and 1.1 for the conventional clinical scans. Conclusions: The proposed DCE-MRI approach provides clinically superior image quality with higher spatial resolution and coverage than currently available approaches. These advantages may allow comprehensive permeability mapping in the brain, which is especially valuable in the setting of large lesions or multiple lesions spread throughout the brain.« less

Self-Correcting Electronically-Scanned Pressure Sensor

NASA Technical Reports Server (NTRS)

Gross, C.; Basta, T.

1982-01-01

High-data-rate sensor automatically corrects for temperature variations. Multichannel, self-correcting pressure sensor can be used in wind tunnels, aircraft, process controllers and automobiles. Offers data rates approaching 100,000 measurements per second with inaccuracies due to temperature shifts held below 0.25 percent (nominal) of full scale over a temperature span of 55 degrees C.

A reduced graphene oxide/Co 3O 4 composite for supercapacitor electrode

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

Xiang, Chengcheng; Li, Ming; Zhi, Mingjia

2013-03-01

20 nm sized Co 3O 4 nanoparticles are in-situ grown on the chemically reduced graphene oxide (rGO) sheets to form a rGO-Co 3O 4 composite during hydrothermal processing. The rGO-Co 3O 4 composite is employed as the pseudocapacitor electrode in the 2 M KOH aqueous electrolyte solution. The rGOCo 3O 4 composite electrode exhibits a specific capacitance of 472 F/g at a scan rate of 2 mV/s in a two-electrode cell. 82.6% of capacitance is retained when the scan rate increases to 100 mV/s. The rGOCo 3O 4 composite electrode shows high rate capability and excellent long-term stability. It alsomore » exhibits high energy density at relatively high power density. The energy density reaches 39.0 Wh/kg at a power density of 8.3 kW/kg. The super performance of the composite electrode is attributed to the synergistic effects of small size and good redox activity of the Co 3O 4 particles combined with high electronic conductivity of the rGO sheets.« less

Mini-excimer laser corneal reshaping using a scanning device

NASA Astrophysics Data System (ADS)

Lin, Jui T.

1994-07-01

In this paper we present an update on the Mini-Excimer photorefractive keratectomy (PRK) laser system with an emphasis on the scanning device. We also compare the systems of various manufacturers. This paper also presents PMMA ablation profiles and clinical results from China with over 100 cases of myopic corrections ranging from -2.5 D to -12 D. In contrast to the old technology which uses industrial-type high-power excimer lasers, the advanced Mini-Excimer system uses the most recent technology involving a compact, high repetition-rate excimer laser operated at a much smaller beam spot size of (0.8 - 1.2) mm in a scanning mode which requires a beam energy per pulse of only (0.9 - 1.2) mJ on the corneal surface to achieve the same range of fluence (or energy density) (160 - 200) mJ/cm2 as that of the high-power excimer lasers.

Perceptual Characterization of the Macronutrient Picture System (MaPS) for Food Image fMRI

PubMed Central

King, Jill L.; Fearnbach, S. Nicole; Ramakrishnapillai, Sreekrishna; Shankpal, Preetham; Geiselman, Paula J.; Martin, Corby K.; Murray, Kori B.; Hicks, Jason L.; McClernon, F. Joseph; Apolzan, John W.; Carmichael, Owen T.

2018-01-01

Food image fMRI paradigms are used widely for investigating the neural basis of ingestive behavior. However, these paradigms have not been validated in terms of ingestive behavior constructs, engagement of food-relevant neural systems, or test-retest reliability, making the generalizability of study findings unclear. Therefore, we validated the Macronutrient Picture System (MaPS) (McClernon et al., 2013), which includes food images from the six categories represented in the Geiselman Food Preference Questionnaire (FPQ) (Geiselman et al., 1998). Twenty-five healthy young adults (n = 21 female, mean age = 20.6 ± 1.1 years, mean BMI = 22.1 ± 1.9 kg/m2) rated the MaPS images in terms of visual interest, appetitive quality, nutrition, emotional valence, liking, and frequency of consumption, and completed the FPQ. In a second study, 12 individuals (n=8 female, mean age = 25.0 ± 6.5 years, mean BMI = 28.2 ± 8.7 kg/m2) viewed MaPS and control images (vegetables and non-food) during two separate 3T BOLD fMRI scans after fasting overnight. Intuitively, high fat/high sugar (HF/HS) and high fat/high complex carbohydrate (HF/HCCHO) images achieved higher liking and appetitive ratings, and lower nutrition ratings, than low fat/low complex carbohydrate/high protein (LF/LCHO/HP) images on average. Within each food category, FPQ scores correlated strongly with MaPS image liking ratings (p < 0.001). Brain activation differences between viewing images of HF/HS and vegetables, and between HF/HCCHO and vegetables, were seen in several reward-related brain regions (e.g., putamen, insula, and medial frontal gyrus). Intra-individual, inter-scan agreement in a summary measure of brain activation differences in seven reward network regions of interest was high (ICC = 0.61), and was even higher when two distinct sets of food images with matching visual ratings were shown in the two scans (ICC = 0.74). These results suggest that the MaPS provides valid representation of food categories and reliably activates food-reward-relevant neural systems. PMID:29434559

Evaluation of an internet-based animated preparatory video for children undergoing non-sedated MRI.

PubMed

McGlashan, Hannah L; Dineen, Rob A; Szeszak, Sofia; Whitehouse, William P; Chow, Gabriel; Love, Andrew; Langmack, Gill; Wharrad, Heather

2018-05-10

We evaluate the value of an internet-based educational animated video designed to prepare children for MRI scans, and whether this video reduces scan-related anxiety in children with a neurological disorder, and healthy controls. Participants completed a pre- and post-scan questionnaire evaluating participant online viewing behaviour, understanding of the MRI procedure, anxiety regarding the MRI, impact of animation in preparing the child and whether the child's expectation of the MRI scan matched their experience. 21 children were recruited (12 healthy controls) ranging in age from 6.5 to 11.5 years. The animation was successfully accessed by participants on a range of digital devices and had high levels of approval. Children who viewed the animation had a good understanding of the MRI procedure and low anxiety levels prior to the scan, and reported that their expectations broadly matched the real-life MRI experience. Children reported that the animation positively impacted on their preparation with similar ratings before and after the scan, and the impact on preparation was rated greater by younger children. There were no group differences between healthy children and those with the neurological disorder for ratings of anxiety, impact on preparation and expectation of the experience. This evaluation demonstrates accessibility, acceptability and relevance of internet-based educational animation for typically developing children, and children with a neurodisability aged 6 to 11 years, with positive impact on preparation for MRI. Advances in knowledge: The internet-based educational animation provides a widely accessible tool to support preparation of children for non-sedated MRI.

A comparison of sequential and spiral scanning techniques in brain CT.

PubMed

Pace, Ivana; Zarb, Francis

2015-01-01

To evaluate and compare image quality and radiation dose of sequential computed tomography (CT) examinations of the brain and spiral CT examinations of the brain imaged on a GE HiSpeed NX/I Dual Slice 2CT scanner. A random sample of 40 patients referred for CT examination of the brain was selected and divided into 2 groups. Half of the patients were scanned using the sequential technique; the other half were scanned using the spiral technique. Radiation dose data—both the computed tomography dose index (CTDI) and the dose length product (DLP)—were recorded on a checklist at the end of each examination. Using the European Guidelines on Quality Criteria for Computed Tomography, 4 radiologists conducted a visual grading analysis and rated the level of visibility of 6 anatomical structures considered necessary to produce images of high quality. The mean CTDI(vol) and DLP values were statistically significantly higher (P <.05) with the sequential scans (CTDI(vol): 22.06 mGy; DLP: 304.60 mGy • cm) than with the spiral scans (CTDI(vol): 14.94 mGy; DLP: 229.10 mGy • cm). The mean image quality rating scores for all criteria of the sequential scanning technique were statistically significantly higher (P <.05) in the visual grading analysis than those of the spiral scanning technique. In this local study, the sequential technique was preferred over the spiral technique for both overall image quality and differentiation between gray and white matter in brain CT scans. Other similar studies counter this finding. The radiation dose seen with the sequential CT scanning technique was significantly higher than that seen with the spiral CT scanning technique. However, image quality with the sequential technique was statistically significantly superior (P <.05).

Capacitive behavior of highly-oxidized graphite

NASA Astrophysics Data System (ADS)

Ciszewski, Mateusz; Mianowski, Andrzej

2014-09-01

Capacitive behavior of a highly-oxidized graphite is presented in this paper. The graphite oxide was synthesized using an oxidizing mixture of potassium chlorate and concentrated fuming nitric acid. As-oxidized graphite was quantitatively and qualitatively analyzed with respect to the oxygen content and the species of oxygen-containing groups. Electrochemical measurements were performed in a two-electrode symmetric cell using KOH electrolyte. It was shown that prolonged oxidation causes an increase in the oxygen content while the interlayer distance remains constant. Specific capacitance increased with oxygen content in the electrode as a result of pseudo-capacitive effects, from 0.47 to 0.54 F/g for a scan rate of 20 mV/s and 0.67 to 1.15 F/g for a scan rate of 5 mV/s. Better cyclability was observed for the electrode with a higher oxygen amount.

Goddard Conference on Mass Storage Systems and Technologies, Volume 1

NASA Technical Reports Server (NTRS)

Kobler, Ben (Editor); Hariharan, P. C. (Editor)

1993-01-01

Copies of nearly all of the technical papers and viewgraphs presented at the Goddard Conference on Mass Storage Systems and Technologies held in Sep. 1992 are included. The conference served as an informational exchange forum for topics primarily relating to the ingestion and management of massive amounts of data and the attendant problems (data ingestion rates now approach the order of terabytes per day). Discussion topics include the IEEE Mass Storage System Reference Model, data archiving standards, high-performance storage devices, magnetic and magneto-optic storage systems, magnetic and optical recording technologies, high-performance helical scan recording systems, and low end helical scan tape drives. Additional topics addressed the evolution of the identifiable unit for processing purposes as data ingestion rates increase dramatically, and the present state of the art in mass storage technology.

In vivo imaging of the rodent eye with swept source/Fourier domain OCT

PubMed Central

Liu, Jonathan J.; Grulkowski, Ireneusz; Kraus, Martin F.; Potsaid, Benjamin; Lu, Chen D.; Baumann, Bernhard; Duker, Jay S.; Hornegger, Joachim; Fujimoto, James G.

2013-01-01

Swept source/Fourier domain OCT is demonstrated for in vivo imaging of the rodent eye. Using commercial swept laser technology, we developed a prototype OCT imaging system for small animal ocular imaging operating in the 1050 nm wavelength range at an axial scan rate of 100 kHz with ~6 µm axial resolution. The high imaging speed enables volumetric imaging with high axial scan densities, measuring high flow velocities in vessels, and repeated volumetric imaging over time. The 1050 nm wavelength light provides increased penetration into tissue compared to standard commercial OCT systems at 850 nm. The long imaging range enables multiple operating modes for imaging the retina, posterior eye, as well as anterior eye and full eye length. A registration algorithm using orthogonally scanned OCT volumetric data sets which can correct motion on a per A-scan basis is applied to compensate motion and merge motion corrected volumetric data for enhanced OCT image quality. Ultrahigh speed swept source OCT is a promising technique for imaging the rodent eye, proving comprehensive information on the cornea, anterior segment, lens, vitreous, posterior segment, retina and choroid. PMID:23412778

Development of scanning holographic display using MEMS SLM

NASA Astrophysics Data System (ADS)

Takaki, Yasuhiro

2016-10-01

Holography is an ideal three-dimensional (3D) display technique, because it produces 3D images that naturally satisfy human 3D perception including physiological and psychological factors. However, its electronic implementation is quite challenging because ultra-high resolution is required for display devices to provide sufficient screen size and viewing zone. We have developed holographic display techniques to enlarge the screen size and the viewing zone by use of microelectromechanical systems spatial light modulators (MEMS-SLMs). Because MEMS-SLMs can generate hologram patterns at a high frame rate, the time-multiplexing technique is utilized to virtually increase the resolution. Three kinds of scanning systems have been combined with MEMS-SLMs; the screen scanning system, the viewing-zone scanning system, and the 360-degree scanning system. The screen scanning system reduces the hologram size to enlarge the viewing zone and the reduced hologram patterns are scanned on the screen to increase the screen size: the color display system with a screen size of 6.2 in. and a viewing zone angle of 11° was demonstrated. The viewing-zone scanning system increases the screen size and the reduced viewing zone is scanned to enlarge the viewing zone: a screen size of 2.0 in. and a viewing zone angle of 40° were achieved. The two-channel system increased the screen size to 7.4 in. The 360-degree scanning increases the screen size and the reduced viewing zone is scanned circularly: the display system having a flat screen with a diameter of 100 mm was demonstrated, which generates 3D images viewed from any direction around the flat screen.

Effect of parameters on picosecond laser ablation of Cr12MoV cold work mold steel

NASA Astrophysics Data System (ADS)

Wu, Baoye; Liu, Peng; Zhang, Fei; Duan, Jun; Wang, Xizhao; Zeng, Xiaoyan

2018-01-01

Cr12MoV cold work mold steel, which is a difficult-to-machining material, is widely used in the mold and dye industry. A picosecond pulse Nd:YVO4 laser at 1064 nm was used to conduct the study. Effects of operation parameters (i.e., laser fluence, scanning speed, hatched space and number of scans) were studied on ablation depth and quality of Cr12MoV at the repetition rate of 20 MHz. The experimental results reveal that all the four parameters affect the ablation depth significantly. While the surface roughness depends mainly on laser fluence or scanning speed and secondarily on hatched space or number of scans. For laser fluence and scanning speed, three distinct surface morphologies were observed experiencing transition from flat (Ra < 1.40 μm) to bumpy (Ra = 1.40 - 2.40 μm) eventually to rough (Ra > 2.40 μm). However, for hatched space and number of scan, there is a small bumpy and rough zone or even no rough zone. Mechanisms including heat accumulation, plasma shielding and combustion reaction effects are proposed based on the ablation depth and processing morphology. By appropriate management of the laser fluence and scanning speed, high ablation depth with low surface roughness can be obtained at small hatched space and high number of scans.

Geographical Clusters of Rape in the United States: 2000-2012

PubMed Central

Amin, Raid; Nabors, Nicole S.; Nelson, Arlene M.; Saqlain, Murshid; Kulldorff, Martin

2016-01-01

Background While rape is a very serious crime and public health problem, no spatial mapping has been attempted for rape on the national scale. This paper addresses the three research questions: (1) Are reported rape cases randomly distributed across the USA, after being adjusted for population density and age, or are there geographical clusters of reported rape cases? (2) Are the geographical clusters of reported rapes still present after adjusting for differences in poverty levels? (3) Are there geographical clusters where the proportion of reported rape cases that lead to an arrest is exceptionally low or exceptionally high? Methods We studied the geographical variation of reported rape events (2003-2012) and rape arrests (2000-2012) in the 48 contiguous states of the USA. The disease Surveillance software SaTScan™ with its spatial scan statistic is used to evaluate the spatial variation in rapes. The spatial scan statistic has been widely used as a geographical surveillance tool for diseases, and we used it to identify geographical areas with clusters of reported rape and clusters of arrest rates for rape. Results The spatial scan statistic was used to identify geographical areas with exceptionally high rates of reported rape. The analyses were adjusted for age, and in secondary analyses, for both age and poverty level. We also identified geographical areas with either a low or a high proportion of reported rapes leading to an arrest. Conclusions We have identified geographical areas with exceptionally high (low) rates of reported rape. The geographical problem areas identified are prime candidates for more intensive preventive counseling and criminal prosecution efforts by public health, social service, and law enforcement agencies Geographical clusters of high rates of reported rape are prime areas in need of expanded implementation of preventive measures, such as changing attitudes in our society toward rape crimes, in addition to having the criminal justice system play an even larger role in preventing rape. PMID:28078318

Geographical Clusters of Rape in the United States: 2000-2012.

PubMed

Amin, Raid; Nabors, Nicole S; Nelson, Arlene M; Saqlain, Murshid; Kulldorff, Martin

2015-01-01

While rape is a very serious crime and public health problem, no spatial mapping has been attempted for rape on the national scale. This paper addresses the three research questions: (1) Are reported rape cases randomly distributed across the USA, after being adjusted for population density and age, or are there geographical clusters of reported rape cases? (2) Are the geographical clusters of reported rapes still present after adjusting for differences in poverty levels? (3) Are there geographical clusters where the proportion of reported rape cases that lead to an arrest is exceptionally low or exceptionally high? We studied the geographical variation of reported rape events (2003-2012) and rape arrests (2000-2012) in the 48 contiguous states of the USA. The disease Surveillance software SaTScan™ with its spatial scan statistic is used to evaluate the spatial variation in rapes. The spatial scan statistic has been widely used as a geographical surveillance tool for diseases, and we used it to identify geographical areas with clusters of reported rape and clusters of arrest rates for rape. The spatial scan statistic was used to identify geographical areas with exceptionally high rates of reported rape. The analyses were adjusted for age, and in secondary analyses, for both age and poverty level. We also identified geographical areas with either a low or a high proportion of reported rapes leading to an arrest. We have identified geographical areas with exceptionally high (low) rates of reported rape. The geographical problem areas identified are prime candidates for more intensive preventive counseling and criminal prosecution efforts by public health, social service, and law enforcement agencies Geographical clusters of high rates of reported rape are prime areas in need of expanded implementation of preventive measures, such as changing attitudes in our society toward rape crimes, in addition to having the criminal justice system play an even larger role in preventing rape.

Paediatric cerebrovascular CT angiography-towards better image quality.

PubMed

Thust, Stefanie C; Chong, Wui Khean Kling; Gunny, Roxana; Mazumder, Asif; Poitelea, Marius; Welsh, Anna; Ederies, Ash; Mankad, Kshitij

2014-12-01

Paediatric cerebrovascular CT angiography (CTA) can be challenging to perform due to variable cardiovascular physiology between different age groups and the risk of movement artefact. This analysis aimed to determine what proportion of CTA at our institution was of diagnostic quality and identify technical factors which could be improved. a retrospective analysis of 20 cases was performed at a national paediatric neurovascular centre assessing image quality with a subjective scoring system and Hounsfield Unit (HU) measurements. Demographic data, contrast dose, flow rate and triggering times were recorded for each patient. Using a qualitative scoring system, 75% of studies were found to be of diagnostic quality (n=9 'good', n=6 'satisfactory') and 25% (n=5) were 'poor'. Those judged subjectively to be poor had arterial contrast density measured at less than 250 HU. Increased arterial opacification was achieved for cases performed with an increased flow rate (2.5-4 mL/s) and higher intravenous contrast dose (2 mL/kg). Triggering was found to be well timed in nine cases, early in four cases and late in seven cases. Of the scans triggered early, 75% were poor. Of the scans triggered late, less (29%) were poor. High flow rates (>2.5 mL/s) were a key factor for achieving high quality paediatric cerebrovascular CTA imaging. However, appropriate triggering by starting the scan immediately on contrast opacification of the monitoring vessel plays an important role and could maintain image quality when flow rates were lower. Early triggering appeared more detrimental than late.

Video-rate in vivo fluorescence imaging with a line-scanned dual-axis confocal microscope.

PubMed

Chen, Ye; Wang, Danni; Khan, Altaz; Wang, Yu; Borwege, Sabine; Sanai, Nader; Liu, Jonathan T C

2015-10-01

Video-rate optical-sectioning microscopy of living organisms would allow for the investigation of dynamic biological processes and would also reduce motion artifacts, especially for in vivo imaging applications. Previous feasibility studies, with a slow stage-scanned line-scanned dual-axis confocal (LS-DAC) microscope, have demonstrated that LS-DAC microscopy is capable of imaging tissues with subcellular resolution and high contrast at moderate depths of up to several hundred microns. However, the sensitivity and performance of a video-rate LS-DAC imaging system, with low-numerical aperture optics, have yet to be demonstrated. Here, we report on the construction and validation of a video-rate LS-DAC system that possesses sufficient sensitivity to visualize fluorescent contrast agents that are topically applied or systemically delivered in animal and human tissues. We present images of murine oral mucosa that are topically stained with methylene blue, and images of protoporphyrin IX-expressing brain tumor from glioma patients that have been administered 5-aminolevulinic acid prior to surgery. In addition, we demonstrate in vivo fluorescence imaging of red blood cells trafficking within the capillaries of a mouse ear, at frame rates of up to 30 fps. These results can serve as a benchmark for miniature in vivo microscopy devices under development.

Video-rate in vivo fluorescence imaging with a line-scanned dual-axis confocal microscope

NASA Astrophysics Data System (ADS)

Chen, Ye; Wang, Danni; Khan, Altaz; Wang, Yu; Borwege, Sabine; Sanai, Nader; Liu, Jonathan T. C.

2015-10-01

Video-rate optical-sectioning microscopy of living organisms would allow for the investigation of dynamic biological processes and would also reduce motion artifacts, especially for in vivo imaging applications. Previous feasibility studies, with a slow stage-scanned line-scanned dual-axis confocal (LS-DAC) microscope, have demonstrated that LS-DAC microscopy is capable of imaging tissues with subcellular resolution and high contrast at moderate depths of up to several hundred microns. However, the sensitivity and performance of a video-rate LS-DAC imaging system, with low-numerical aperture optics, have yet to be demonstrated. Here, we report on the construction and validation of a video-rate LS-DAC system that possesses sufficient sensitivity to visualize fluorescent contrast agents that are topically applied or systemically delivered in animal and human tissues. We present images of murine oral mucosa that are topically stained with methylene blue, and images of protoporphyrin IX-expressing brain tumor from glioma patients that have been administered 5-aminolevulinic acid prior to surgery. In addition, we demonstrate in vivo fluorescence imaging of red blood cells trafficking within the capillaries of a mouse ear, at frame rates of up to 30 fps. These results can serve as a benchmark for miniature in vivo microscopy devices under development.

Real-time integrated photoacoustic and ultrasound (PAUS) imaging system to guide interventional procedures: ex vivo study.

PubMed

Wei, Chen-Wei; Nguyen, Thu-Mai; Xia, Jinjun; Arnal, Bastien; Wong, Emily Y; Pelivanov, Ivan M; O'Donnell, Matthew

2015-02-01

Because of depth-dependent light attenuation, bulky, low-repetition-rate lasers are usually used in most photoacoustic (PA) systems to provide sufficient pulse energies to image at depth within the body. However, integrating these lasers with real-time clinical ultrasound (US) scanners has been problematic because of their size and cost. In this paper, an integrated PA/US (PAUS) imaging system is presented operating at frame rates >30 Hz. By employing a portable, low-cost, low-pulse-energy (~2 mJ/pulse), high-repetition-rate (~1 kHz), 1053-nm laser, and a rotating galvo-mirror system enabling rapid laser beam scanning over the imaging area, the approach is demonstrated for potential applications requiring a few centimeters of penetration. In particular, we demonstrate here real-time (30 Hz frame rate) imaging (by combining multiple single-shot sub-images covering the scan region) of an 18-gauge needle inserted into a piece of chicken breast with subsequent delivery of an absorptive agent at more than 1-cm depth to mimic PAUS guidance of an interventional procedure. A signal-to-noise ratio of more than 35 dB is obtained for the needle in an imaging area 2.8 × 2.8 cm (depth × lateral). Higher frame rate operation is envisioned with an optimized scanning scheme.

Wavelength-agile diode-laser sensing strategies for monitoring gas properties in optically harsh flows: application in cesium-seeded pulse detonation

NASA Astrophysics Data System (ADS)

Sanders, Scott Thomas; Mattison, Daniel W.; Ma, Lin; Jeffries, Jay B.; Hanson, Ronald K.

2002-06-01

The rapid, broad wavelength scanning capabilities of advanced diode lasers allow extension of traditional diode-laser absorption techniques to high pressure, transient, and generally hostile environments. Here, we demonstrate this extension by applying a vertical cavity surface-emitting laser (VCSEL) to monitor gas temperature and pressure in a pulse detonation engine (PDE). Using aggressive injection current modulation, the VCSEL is scanned through a 10 cm-1 spectral window at megahertz rates roughly 10 times the scanning range and 1000 times the scanning rate of a conventional diode laser. The VCSEL probes absorption lineshapes of the ~ 852 nm D2 transition of atomic Cs, seeded at ~ 5 ppm into the feedstock gases of a PDE. Using these lineshapes, detonated-gas temperature and pressure histories, spanning 2000 4000 K and 0.5 30 atm, respectively, are recorded with microsecond time response. The increasing availability of wavelength-agile diode lasers should support the development of similar sensors for other harsh flows, using other absorbers such as native H2O.

Postprocessing Algorithm for Driving Conventional Scanning Tunneling Microscope at Fast Scan Rates

PubMed Central

Zhang, Hao; Li, Xianqi; Park, Jewook; Li, An-Ping

2017-01-01

We present an image postprocessing framework for Scanning Tunneling Microscope (STM) to reduce the strong spurious oscillations and scan line noise at fast scan rates and preserve the features, allowing an order of magnitude increase in the scan rate without upgrading the hardware. The proposed method consists of two steps for large scale images and four steps for atomic scale images. For large scale images, we first apply for each line an image registration method to align the forward and backward scans of the same line. In the second step we apply a “rubber band” model which is solved by a novel Constrained Adaptive and Iterative Filtering Algorithm (CIAFA). The numerical results on measurement from copper(111) surface indicate the processed images are comparable in accuracy to data obtained with a slow scan rate, but are free of the scan drift error commonly seen in slow scan data. For atomic scale images, an additional first step to remove line-by-line strong background fluctuations and a fourth step of replacing the postprocessed image by its ranking map as the final atomic resolution image are required. The resulting image restores the lattice image that is nearly undetectable in the original fast scan data. PMID:29362664

Hydrothermal synthesis of poly(3,4-ethylenedioxythiophene) for high-rate performance supercapacitor

NASA Astrophysics Data System (ADS)

Ahmed, Sultan; Parvaz, M.; Johari, Rahul; Bilal, M.; Ahmad, Sultan; Zaid, M.; Hussain, S.; Islamuddin, Khan, Zishan H.; Rafat, M.

2018-05-01

This work reports the successful preparation of Poly (3,4-ethylenedioxythiophene) (PEDOT) from monomer ethylenedioxythiophene (EDOT), employing hydrothermal method. The structure of the prepared sample was characterized by Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) and the results indicates the successful polymerization of EDOT to the formation of polymer PEDOT. The capacitive performance of the prepared sample were investigated in two-electrode assembly using aqueous solution of 6 M KOH. The assembled capacitor cell shows high rate capability which is evident from both cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) studies. The observed CV patterns are almost rectangular even for high scan rates (˜30 V s-1), confirming the high rate performance, while high knee frequency (˜1 kHz), and low response time (˜5.8 ms) observed by impedance analysis confirms the high rate capability of supercapacitor.

InSAR time series analysis of ALOS-2 ScanSAR data and its implications for NISAR

NASA Astrophysics Data System (ADS)

Liang, C.; Liu, Z.; Fielding, E. J.; Huang, M. H.; Burgmann, R.

2017-12-01

The JAXA's ALOS-2 mission was launched on May 24, 2014. It operates at L-band and can acquire data in multiple modes. ScanSAR is the main operational mode and has a 350 km swath, somewhat larger than the 250 km swath of the SweepSAR mode planned for the NASA-ISRO SAR (NISAR) mission. ALOS-2 has been acquiring a wealth of L-band InSAR data. These data are of particular value in areas of dense vegetation and high relief. The InSAR technical development for ALOS-2 also enables the preparation for the upcoming NISAR mission. We have been developing advanced InSAR processing techniques for ALOS-2 over the past two years. Here, we report the important issues for doing InSAR time series analysis using ALOS-2 ScanSAR data. First, we present ionospheric correction techniques for both regular ScanSAR InSAR and MAI (multiple aperture InSAR) ScanSAR InSAR. We demonstrate the large-scale ionospheric signals in the ScanSAR interferograms. They can be well mitigated by the correction techniques. Second, based on our technical development of burst-by-burst InSAR processing for ALOS-2 ScanSAR data, we find that the azimuth Frequency Modulation (FM) rate error is an important issue not only for MAI, but also for regular InSAR time series analysis. We identify phase errors caused by azimuth FM rate errors during the focusing process of ALOS-2 product. The consequence is mostly a range ramp in the InSAR time series result. This error exists in all of the time series results we have processed. We present the correction techniques for this error following a theoretical analysis. After corrections, we present high quality ALOS-2 ScanSAR InSAR time series results in a number of areas. The development for ALOS-2 can provide important implications for NISAR mission. For example, we find that in most cases the relative azimuth shift caused by ionosphere can be as large as 4 m in a large area imaged by ScanSAR. This azimuth shift is half of the 8 m azimuth resolution of the SweepSAR mode planned for NISAR, which implies that a good coregistration strategy for NISAR's SweepSAR mode is geometrical coregistration followed by MAI or spectral diversity analysis. Besides, our development also provides implications for the processing and system parameter requirements of NISAR, such as the accuracy requirement of azimuth FM rate and range timing.

Influence of spatial and temporal spot distribution on the ocular surface quality and maximum ablation depth after photoablation with a 1050 Hz excimer laser system.

PubMed

Mrochen, Michael; Schelling, Urs; Wuellner, Christian; Donitzky, Christof

2009-02-01

To investigate the effect of temporal and spatial distributions of laser spots (scan sequences) on the corneal surface quality after ablation and the maximum ablation of a given refractive correction after photoablation with a high-repetition-rate scanning-spot laser. IROC AG, Zurich, Switzerland, and WaveLight AG, Erlangen, Germany. Bovine corneas and poly(methyl methacrylate) (PMMA) plates were photoablated using a 1050 Hz excimer laser prototype for corneal laser surgery. Four temporal and spatial spot distributions (scan sequences) with different temporal overlapping factors were created for 3 myopic, 3 hyperopic, and 3 phototherapeutic keratectomy ablation profiles. Surface quality and maximum ablation depth were measured using a surface profiling system. The surface quality factor increased (rough surfaces) as the amount of temporal overlapping in the scan sequence and the amount of correction increased. The rise in surface quality factor was less for bovine corneas than for PMMA. The scan sequence might cause systematic substructures at the surface of the ablated material depending on the overlapping factor. The maximum ablation varied within the scan sequence. The temporal and spatial distribution of the laser spots (scan sequence) during a corneal laser procedure affected the surface quality and maximum ablation depth of the ablation profile. Corneal laser surgery could theoretically benefit from smaller spot sizes and higher repetition rates. The temporal and spatial spot distributions are relevant to achieving these aims.

OCT minimum intensity as a predictor of geographic atrophy enlargement.

PubMed

Stetson, Paul F; Yehoshua, Zohar; Garcia Filho, Carlos Alexandre A; Portella Nunes, Renata; Gregori, Giovanni; Rosenfeld, Philip J

2014-02-10

We determined whether the minimum intensity (MI) of the optical coherence tomography (OCT) A-scans within the retina can predict locations of growth at the margin of geographic atrophy (GA) and the growth rate outside the margin. The OCT scans were analyzed at baseline and 52 weeks. Expert graders manually segmented OCT images of GA. The 52-week follow-up scans were registered to the baseline scan coordinates for comparison. The OCT MI values were studied within a 180-μm margin around the boundary of GA at baseline. Baseline MI values were compared in areas of progression and nonprogression of the GA, and sensitivity and specificity were assessed for prediction of growth at the margin. Average MI values in the margins were compared to overall growth rates to evaluate the prediction of growth outside the margins. A statistically significant increase in MI (P < 0.05) was seen in areas of growth in 21/24 cases (88%), and 22/24 cases (92%) when the foveal subfield was excluded. Locations of growth within the margins at 52 weeks were predicted with 61% sensitivity and 61% specificity. The MI values correlated significantly with overall growth rate, and high and low growth rate subjects were identified with 80% sensitivity and 64% specificity. The MI may be increased at the margins of GA lesions before enlargement, which may indicate disruption or atrophy of the photoreceptors in these areas before GA becomes apparent. Increased MI may help predict areas of enlargement of GA, and may relate to overall growth rate and be a useful screening tool for GA. (ClinicalTrials.gov number, NCT00935883.).

Characterization of FBG sensor interrogation based on a FDML wavelength swept laser

PubMed Central

Jung, Eun Joo; Kim, Chang-Seok; Jeong, Myung Yung; Kim, Moon Ki; Jeon, Min Yong; Jung, Woonggyu; Chen, Zhongping

2012-01-01

In this study, we develop an ultra-fast fiber Bragg grating sensor system that is based on the Fourier domain mode-locked (FDML) swept laser. A FDML wavelength swept laser has many advantages compared to the conventional wavelength swept laser source, such as high-speed interrogation, narrow spectral sensitivity, and high phase stability. The newly developed FDML wavelength swept laser shows a superior performance of a high scan rate of 31.3 kHz and a broad scan range of over 70 nm simultaneously. The performance of the grating sensor interrogating system using a FDML wavelength swept laser is characterized in both static and dynamic strain responses. PMID:18852764

Ultrafast CT scanning of an oak log for internal defects

Treesearch

Francis G. Wagner; Fred W. Taylor; Douglas S. Ladd; Charles W. McMillin; Fredrick L. Roder

1989-01-01

Detecting internal defects in sawlogs and veneer logs with computerized tomographic (CT) scanning is possible, but has been impractical due to the long scanning time required. This research investigated a new scanner able to acquire 34 cross-sectional log scans per second. This scanning rate translates to a linear log feed rate of 85 feet (25.91 m) per minute at one...

Ni foam supported quasi-core-shell structure of ultrathin Ti3C2 nanosheets through electrostatic layer-by-layer self-assembly as high rate-performance electrodes of supercapacitors

NASA Astrophysics Data System (ADS)

Tian, Yapeng; Yang, Chenhui; Que, Wenxiu; He, Yucheng; Liu, Xiaobin; Luo, Yangyang; Yin, Xingtian; Kong, Ling Bing

2017-11-01

Supercapacitor, as an important energy storage device, is a critical component for next generation electric power system, due to its high power density and long cycle life. In this study, a novel electrode material with quasi-core-shell structure, consisting of negatively charged few layer Ti3C2 nanosheets (FL-Ti3C2) and positively charged polyethyleneimine as building blocks, has been prepared by using an electrostatic layer-by-layer self-assembly method, with highly conductive Ni foam to be used as the skeleton. The unique quasi-core-shell structured ultrathin Ti3C2 nanosheets provide an excellent electron channel, ion transport channel and large effective contact area, thus leading to a great improvement in electrochemical performance of the material. The specific capacitance of the binder-free FL-Ti3C2@Ni foam electrodes reaches 370 F g-1 at the scan rate of 2 mV s-1 and a specific capacitance of 117 F g-1 is obtained even at the scan rate of 1000 mV s-1 in the electrolyte of Li2SO4, indicating a high rate performance. In addition, this electrode shows a long-term cyclic stability with a loss of only 13.7% after 10,000 circles. Furthermore, quantitative analysis has been conducted to ensure the relationship between the capacitive contribution and the rate performance of the as-fabricated electrode.

Irreversible Denaturation of Maltodextrin Glucosidase Studied by Differential Scanning Calorimetry, Circular Dichroism, and Turbidity Measurements

PubMed Central

Goyal, Megha; Chaudhuri, Tapan K.; Kuwajima, Kunihiro

2014-01-01

Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5–1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C). PMID:25548918

Irreversible denaturation of maltodextrin glucosidase studied by differential scanning calorimetry, circular dichroism, and turbidity measurements.

PubMed

Goyal, Megha; Chaudhuri, Tapan K; Kuwajima, Kunihiro

2014-01-01

Thermal denaturation of Escherichia coli maltodextrin glucosidase was studied by differential scanning calorimetry, circular dichroism (230 nm), and UV-absorption measurements (340 nm), which were respectively used to monitor heat absorption, conformational unfolding, and the production of solution turbidity. The denaturation was irreversible, and the thermal transition recorded at scan rates of 0.5-1.5 K/min was significantly scan-rate dependent, indicating that the thermal denaturation was kinetically controlled. The absence of a protein-concentration effect on the thermal transition indicated that the denaturation was rate-limited by a mono-molecular process. From the analysis of the calorimetric thermograms, a one-step irreversible model well represented the thermal denaturation of the protein. The calorimetrically observed thermal transitions showed excellent coincidence with the turbidity transitions monitored by UV-absorption as well as with the unfolding transitions monitored by circular dichroism. The thermal denaturation of the protein was thus rate-limited by conformational unfolding, which was followed by a rapid irreversible formation of aggregates that produced the solution turbidity. It is thus important to note that the absence of the protein-concentration effect on the irreversible thermal denaturation does not necessarily means the absence of protein aggregation itself. The turbidity measurements together with differential scanning calorimetry in the irreversible thermal denaturation of the protein provided a very effective approach for understanding the mechanisms of the irreversible denaturation. The Arrhenius-equation parameters obtained from analysis of the thermal denaturation were compared with those of other proteins that have been reported to show the one-step irreversible thermal denaturation. Maltodextrin glucosidase had sufficiently high kinetic stability with a half-life of 68 days at a physiological temperature (37°C).

Nano-Se: Cheap and easy-to-obtain novel material for all-dielectric nano-photonics

NASA Astrophysics Data System (ADS)

Ivanova, A. K.; Ionin, A. A.; Khmel'nitskii, R. A.; Klevkov, Yu. K.; Kudryashov, S. I.; Levchenko, A. O.; Mel'nik, N. N.; Nastulyavichus, A. A.; Rudenko, A. A.; Saraeva, I. N.; Smirnov, N. A.; Zayarny, D. A.; Gonchukov, S. A.; Tolordava, E. R.; Baranov, A. N.

2017-09-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through few W, kHz-rate nanosecond laser ablation of a solid selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of crater depths and topographies. Deposited particles were inspected by scanning electron microscopy, while optical transmission Raman and dynamic light scattering spectroscopy characterized their hydrosols.

Long-range time-of-flight scanning sensor based on high-speed time-correlated single-photon counting

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

McCarthy, Aongus; Collins, Robert J.; Krichel, Nils J.

2009-11-10

We describe a scanning time-of-flight system which uses the time-correlated single-photon counting technique to produce three-dimensional depth images of distant, noncooperative surfaces when these targets are illuminated by a kHz to MHz repetition rate pulsed laser source. The data for the scene are acquired using a scanning optical system and an individual single-photon detector. Depth images have been successfully acquired with centimeter xyz resolution, in daylight conditions, for low-signature targets in field trials at distances of up to 325 m using an output illumination with an average optical power of less than 50 {mu}W.

(Un)targeted Scanning of Locks of Hair for Drugs of Abuse by Direct Analysis in Real Time-High-Resolution Mass Spectrometry.

PubMed

Duvivier, Wilco F; van Putten, Marc R; van Beek, Teris A; Nielen, Michel W F

2016-02-16

Forensic hair evidence can be used to obtain retrospective timelines of drug use by analysis of hair segments. However, this is a laborious and time-consuming process, and mass spectrometric (MS) imaging techniques, which show great potential for single-hair targeted analysis, are less useful due to differences in hair growth rate between individual hairs. As an alternative, a fast untargeted analysis method was developed that uses direct analysis in real time-high-resolution mass spectrometry (DART-HRMS) to longitudinally scan intact locks of hair without extensive sample preparation or segmentation. The hair scan method was validated for cocaine against an accredited liquid chromatography/tandem mass spectrometry (LC/MS/MS) method. The detection limit for cocaine in hair was found to comply with the cutoff value of 0.5 ng/mg recommended by the Society of Hair Testing; that is, the DART hair scan method is amenable to forensic cases. Under DART conditions, no significant thermal degradation of cocaine occurred. The standard DART spot size of 5.1 ± 1.1 mm could be improved to 3.3 ± 1.0 mm, corresponding to approximately 10 days of hair growth, by using a high spatial resolution exit cone. By use of data-dependent product ion scans, multiple drugs of abuse could be detected in a single drug user hair scan with confirmation of identity by both exact mass and MS/HRMS fragmentation patterns. Furthermore, full-scan high-resolution data were retrospectively interrogated versus a list of more than 100 compounds and revealed additional hits and temporal profiles in good correlation with reported drug use.

A fully integrated mixed-signal neural processor for implantable multichannel cortical recording.

PubMed

Sodagar, Amir M; Wise, Kensall D; Najafi, Khalil

2007-06-01

A 64-channel neural processor has been developed for use in an implantable neural recording microsystem. In the Scan Mode, the processor is capable of detecting neural spikes by programmable positive, negative, or window thresholding. Spikes are tagged with their associated channel addresses and formed into 18-bit data words that are sent serially to the external host. In the Monitor Mode, two channels can be selected and viewed at high resolution for studies where the entire signal is of interest. The processor runs from a 3-V supply and a 2-MHz clock, with a channel scan rate of 64 kS/s and an output bit rate of 2 Mbps.

Studies of localized corrosion in welded aluminum alloys by the scanning reference electrode technique

NASA Technical Reports Server (NTRS)

Danford, M. D.; Nunes, A. C.

1995-01-01

Localized corrosion in welded samples of 2219-T87 Al alloy (2319 filler), 2090 Al-Li alloy (4043 and 2319 fillers), and 2195 Al-Li alloy (4043 and 2319 fillers) has been investigated using the relatively new scanning reference electrode technique. The weld beads are cathodic in all cases, leading to reduced anode/cathode ratios. A reduction in anode/cathode ratio leads to an increase in the corrosion rates of the welded metals, in agreement with results obtained in previous electrochemical and stress corrosion studies involving the overall corrosion rates of welded samples. The cathodic weld beads are bordered on both sides by strong anodic regions, with high propensity for corrosion.

In-situ microwave irradiation synthesis of ZnO-graphene nanocomposite for high-performance supercapacitor applications

NASA Astrophysics Data System (ADS)

Gunaseelan, R.; Venkatachalam, V.; Raj, A. Antony

2018-04-01

In this paper, the ZnO/G nanocomposite was synthesized by facile in-situ microwave irradiation method. The as-prepared ZnO/G composite has been characterized with X-ray powder diffraction. The electrochemical properties of the obtained composite electrode for supercapacitor have been studied by cyclic voltammetry and electrochemical impedance spectra analyses. The ZnO/G nanocomposites showed a good capacitive behavior with a higher specific capacitance of 140.4 F/g at a scan rate of 5 mV/s scan rate in 1M KOH electrolyte. Based on the electrochemical results revealed that the composite electrode is a suitable candidate for supercapacitor applications.

High-performance nanostructured supercapacitors on a sponge.

PubMed

Chen, Wei; Rakhi, R B; Hu, Liangbing; Xie, Xing; Cui, Yi; Alshareef, H N

2011-12-14

A simple and scalable method has been developed to fabricate nanostructured MnO2-carbon nanotube (CNT)-sponge hybrid electrodes. A novel supercapacitor, henceforth referred to as "sponge supercapacitor", has been fabricated using these hybrid electrodes with remarkable performance. A specific capacitance of 1,230 F/g (based on the mass of MnO2) can be reached. Capacitors based on CNT-sponge substrates (without MnO2) can be operated even under a high scan rate of 200 V/s, and they exhibit outstanding cycle performance with only 2% degradation after 100,000 cycles under a scan rate of 10 V/s. The MnO2-CNT-sponge supercapacitors show only 4% of degradation after 10,000 cycles at a charge-discharge specific current of 5 A/g. The specific power and energy of the MnO2-CNT-sponge supercapacitors are high with values of 63 kW/kg and 31 Wh/kg, respectively. The attractive performances exhibited by these sponge supercapacitors make them potentially promising candidates for future energy storage systems.

Constructing, connecting and soldering nanostructures by environmental electron beam deposition

NASA Astrophysics Data System (ADS)

Mølhave, Kristian; Nørgaard Madsen, Dorte; Dohn, Søren; Bøggild, Peter

2004-08-01

Highly conductive nanoscale deposits with solid gold cores can be made by electron beam deposition in an environmental scanning electron microscope (ESEM), suggesting the method to be used for constructing, connecting and soldering nanostructures. This paper presents a feasibility study for such applications. We identify several issues related to contamination and unwanted deposition, relevant for deposition in both vacuum (EBD) and environmental conditions (EEBD). We study relations between scan rate, deposition rate, angle and line width for three-dimensional structures. Furthermore, we measure the conductivity of deposits containing gold cores, and find these structures to be highly conductive, approaching the conductivity of solid gold and capable of carrying high current densities. Finally, we study the use of the technique for soldering nanostructures such as carbon nanotubes. Based on the presented results we are able to estimate limits for the applicability of the method for the various applications, but also demonstrate that it is a versatile and powerful tool for nanotechnology within these limits.

Microstructure and pseudocapacitive properties of electrodes constructed of oriented NiO-TiO2 nanotube arrays.

PubMed

Kim, Jae-Hun; Zhu, Kai; Yan, Yanfa; Perkins, Craig L; Frank, Arthur J

2010-10-13

We report on the synthesis and electrochemical properties of oriented NiO-TiO(2) nanotube (NT) arrays as electrodes for supercapacitors. The morphology of the films prepared by electrochemically anodizing Ni-Ti alloy foils was characterized by scanning and transmission electron microscopies, X-ray diffraction, and photoelectron spectroscopies. The morphology, crystal structure, and composition of the NT films were found to depend on the preparation conditions (anodization voltage and postgrowth annealing temperature). Annealing the as-grown NT arrays to a temperature of 600 °C transformed them from an amorphous phase to a mixture of crystalline rock salt NiO and rutile TiO(2). Changes in the morphology and crystal structure strongly influenced the electrochemical properties of the NT electrodes. Electrodes composed of NT films annealed at 600 °C displayed pseudocapacitor (redox-capacitor) behavior, including rapid charge/discharge kinetics and stable long-term cycling performance. At similar film thicknesses and surface areas, the NT-based electrodes showed a higher rate capability than the randomly packed nanoparticle-based electrodes. Even at the highest scan rate (500 mV/s), the capacitance of the NT electrodes was not much smaller (within 12%) than the capacitance measured at the slowest scan rate (5 mV/s). The faster charge/discharge kinetics of NT electrodes at high scan rates is attributed to the more ordered NT film architecture, which is expected to facilitate electron and ion transport during the charge-discharge reactions.

A coherent light scanner for optical processing of large format transparencies

NASA Technical Reports Server (NTRS)

Callen, W. R.; Weaver, J. E.; Shackelford, R. G.; Walsh, J. R.

1975-01-01

A laser scanner is discussed in which the scanning beam is random-access addressable and perpendicular to the image input plane and the irradiance of the scanned beam is controlled so that a constant average irradiance is maintained after passage through the image plane. The scanner's optical system and design are described, and its performance is evaluated. It is noted that with this scanner, data in the form of large-format transparencies can be processed without the expense, space, maintenance, and precautions attendant to the operation of a high-power laser with large-aperture collimating optics. It is shown that the scanned format as well as the diameter of the scanning beam may be increased by simple design modifications and that higher scan rates can be achieved at the expense of resolution by employing acousto-optic deflectors with different relay optics.

Demand for CT scans increases during transition from paediatric to adult care: an observational study from 2009 to 2015.

PubMed

Thurley, Pete; Crookdake, Jonathan; Norwood, Mark; Sturrock, Nigel; Fogarty, Andrew W

2018-02-01

Avoiding unnecessary radiation exposure is a clinical priority in children and young adults. We aimed to explore demand for CT scans in a busy general hospital with particular interest in the period of transition from paediatric to adult medical care. We used an observational epidemiological study based in a teaching hospital. Data were obtained on numbers and rates of CT scans from 2009 to 2015. The main outcome was age-stratified rates of receiving a CT scan. There were a total of 262,221 CT scans. There was a large step change in the rate of CT scans over the period of transition from paediatric to adult medical care. Individuals aged 10-15 years experienced 6.7 CT scans per 1000 clinical episodes, while those aged 19-24 years experienced 19.8 CT scans per 1000 clinical episodes (p < 0.001). This difference remained significant for all sensitivity analyses. There is almost a threefold increase in rates of CT scans in the two populations before and after the period of transition from paediatric to adult medical care. While we were unable to adjust for case mix or quantify radiation exposure, paediatricians' diagnostic strategies to minimize radiation exposure may have clinical relevance for adult physicians, and hence enable reductions in ionizing radiation to patients. Advances in knowledge: A large increase in rates of CT scans occurs during adolescence, and considering paediatricians' strategies to minimize radiation exposure may enable reductions to all patients.

Studies on niobium triselenide cathode material for lithium rechargeable cells

NASA Technical Reports Server (NTRS)

Ratnakumar, B. V.; Ni, C. L.; Distefano, S.; Somoano, R. B.; Bankston, C. P.

1988-01-01

NbSe3 exhibits superior characteristics such as high capacity, high volumetric and gravimetric energy densities, and high discharge rate capability, as compared to other intercalating cathodes. This paper reports the preparation, characterization, and performance of NbSe3. Several electrochemical techniques, such as cyclic voltammetry, constant-current/constant-potential discharges, dc potentiodynamic scans, ac impedance, and ac voltammetry, have been used to give insight to the mechanisms of intercalation of three lithiums with NbSe3 and also into the rate determining process in the reduction of NbSe3.

Melting temperature and enthalpy variations of phase change materials (PCMs): a differential scanning calorimetry (DSC) analysis

NASA Astrophysics Data System (ADS)

Sun, Xiaoqin; Lee, Kyoung Ok; Medina, Mario A.; Chu, Youhong; Li, Chuanchang

2018-06-01

Differential scanning calorimetry (DSC) analysis is a standard thermal analysis technique used to determine the phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy of phase change materials (PCMs). To determine the appropriate heating rate and sample mass, various DSC measurements were carried out using two kinds of PCMs, namely N-octadecane paraffin and calcium chloride hexahydrate. The variations in phase transition temperature, enthalpy, heat of fusion, specific heat and activation energy were observed within applicable heating rates and sample masses. It was found that the phase transition temperature range increased with increasing heating rate and sample mass; while the heat of fusion varied without any established pattern. The specific heat decreased with the increase of heating rate and sample mass. For accuracy purpose, it is recommended that for PCMs with high thermal conductivity (e.g. hydrated salt) the focus will be on heating rate rather than sample mass.

Activated carbon derived from melaleuca barks for outstanding high-rate supercapacitors

NASA Astrophysics Data System (ADS)

Luo, Qiu-Ping; Huang, Liang; Gao, Xiang; Cheng, Yongliang; Yao, Bin; Hu, Zhimi; Wan, Jun; Xiao, Xu; Zhou, Jun

2015-07-01

Activated carbon (AC) was prepared via carbonizing melaleuca bark in an argon atmosphere at 600 °C followed with KOH activation for high-rate supercapacitors. This AC electrode has a high capacitance of 233 F g-1 at a scan rate of 2 mV s-1 and an excellent rate capability of ˜80% when increasing the sweep rate from 2 to 500 mV s-1. The symmetric supercapacitor assembled by the above electrode can deliver a high energy density of 4.2 Wh kg-1 with a power density of 1500 W kg-1 when operated in the voltage range of 0-1 V in 1 M H2SO4 aqueous electrolyte while maintaining great cycling stability (less than 5% capacitance loss after 10 000 cycles at sweep rate of 100 mV s-1). All the outstanding electrochemical performances make this AC electrode a promising candidate for potential energy storage application.

Mechanical Properties of Transgenic Silkworm Silk Under High Strain Rate Tensile Loading

NASA Astrophysics Data System (ADS)

Chu, J.-M.; Claus, B.; Chen, W.

2017-12-01

Studies have shown that transgenic silkworm silk may be capable of having similar properties of spider silk while being mass-producible. In this research, the tensile stress-strain response of transgenic silkworm silk fiber is systematically characterized using a quasi-static load frame and a tension Kolsky bar over a range of strain-rates between 10^{-3} and 700/s. The results show that transgenic silkworm silk tends to have higher overall ultimate stress and failure strain at high strain rate (700/s) compared to quasi-static strain rates, indicating rate sensitivity of the material. The failure strain at the high strain rate is higher than that of spider silk. However, the stress levels are significantly below that of spider silk, and far below that of high-performance fiber. Failure surfaces are examined via scanning electron microscopy and reveal that the failure modes are similar to those of spider silk.

Feasibility and Limitations of Vaccine Two-Dimensional Barcoding Using Mobile Devices.

PubMed

Bell, Cameron; Guerinet, Julien; Atkinson, Katherine M; Wilson, Kumanan

2016-06-23

Two-dimensional (2D) barcoding has the potential to enhance documentation of vaccine encounters at the point of care. However, this is currently limited to environments equipped with dedicated barcode scanners and compatible record systems. Mobile devices may present a cost-effective alternative to leverage 2D vaccine vial barcodes and improve vaccine product-specific information residing in digital health records. Mobile devices have the potential to capture product-specific information from 2D vaccine vial barcodes. We sought to examine the feasibility, performance, and potential limitations of scanning 2D barcodes on vaccine vials using 4 different mobile phones. A unique barcode scanning app was developed for Android and iOS operating systems. The impact of 4 variables on the scan success rate, data accuracy, and time to scan were examined: barcode size, curvature, fading, and ambient lighting conditions. Two experimenters performed 4 trials 10 times each, amounting to a total of 2160 barcode scan attempts. Of the 1832 successful scans performed in this evaluation, zero produced incorrect data. Five-millimeter barcodes were the slowest to scan, although only by 0.5 seconds on average. Barcodes with up to 50% fading had a 100% success rate, but success rate deteriorated beyond 60% fading. Curved barcodes took longer to scan compared with flat, but success rate deterioration was only observed at a vial diameter of 10 mm. Light conditions did not affect success rate or scan time between 500 lux and 20 lux. Conditions below 20 lux impeded the device's ability to scan successfully. Variability in scan time was observed across devices in all trials performed. 2D vaccine barcoding is possible using mobile devices and is successful under the majority of conditions examined. Manufacturers utilizing 2D barcodes should take into consideration the impact of factors that limit scan success rates. Future studies should evaluate the effect of mobile barcoding on workflow and vaccine administrator acceptance.

Examining drivers' eye glance patterns during distracted driving: Insights from scanning randomness and glance transition matrix.

PubMed

Wang, Yuan; Bao, Shan; Du, Wenjun; Ye, Zhirui; Sayer, James R

2017-12-01

Visual attention to the driving environment is of great importance for road safety. Eye glance behavior has been used as an indicator of distracted driving. This study examined and quantified drivers' glance patterns and features during distracted driving. Data from an existing naturalistic driving study were used. Entropy rate was calculated and used to assess the randomness associated with drivers' scanning patterns. A glance-transition proportion matrix was defined to quantity visual search patterns transitioning among four main eye glance locations while driving (i.e., forward on-road, phone, mirrors and others). All measurements were calculated within a 5s time window under both cell phone and non-cell phone use conditions. Results of the glance data analyses showed different patterns between distracted and non-distracted driving, featured by a higher entropy rate value and highly biased attention transferring between forward and phone locations during distracted driving. Drivers in general had higher number of glance transitions, and their on-road glance duration was significantly shorter during distracted driving when compared to non-distracted driving. Results suggest that drivers have a higher scanning randomness/disorder level and shift their main attention from surrounding areas towards phone area when engaging in visual-manual tasks. Drivers' visual search patterns during visual-manual distraction with a high scanning randomness and a high proportion of eye glance transitions towards the location of the phone provide insight into driver distraction detection. This will help to inform the design of in-vehicle human-machine interface/systems. Copyright © 2017. Published by Elsevier Ltd.

High speed all optical shear wave imaging optical coherence elastography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Song, Shaozhen; Hsieh, Bao-Yu; Wei, Wei; Shen, Tueng; O'Donnell, Matthew; Wang, Ruikang K.

2016-03-01

Optical Coherence Elastography (OCE) is a non-invasive testing modality that maps the mechanical property of soft tissues with high sensitivity and spatial resolution using phase-sensitive optical coherence tomography (PhS-OCT). Shear wave OCE (SW-OCE) is a leading technique that relies on the speed of propagating shear waves to provide a quantitative elastography. Previous shear wave imaging OCT techniques are based on repeated M-B scans, which have several drawbacks such as long acquisition time and repeated wave stimulations. Recent developments of Fourier domain mode-locked high-speed swept-source OCT system has enabled enough speed to perform KHz B-scan rate OCT imaging. Here we propose ultra-high speed, single shot shear wave imaging to capture single-shot transient shear wave propagation to perform SW-OCE. The frame rate of shear wave imaging is 16 kHz, at A-line rate of ~1.62 MHz, which allows the detection of high-frequency shear wave of up to 8 kHz. The shear wave is generated photothermal-acoustically, by ultra-violet pulsed laser, which requires no contact to OCE subjects, while launching high frequency shear waves that carries rich localized elasticity information. The image acquisition and processing can be performed at video-rate, which enables real-time 3D elastography. SW-OCE measurements are demonstrated on tissue-mimicking phantoms and porcine ocular tissue. This approach opens up the feasibility to perform real-time 3D SW-OCE in clinical applications, to obtain high-resolution localized quantitative measurement of tissue biomechanical property.

SU-F-T-173: One-Scan Protocol: Verifying the Delivery of Spot-Scanning Proton Beam

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

Chan, M; Li, J; Chen, C

Purpose: Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. Methods: We performed the calibration using an EBT3 film at depths of 18, 20, 24cm of Plastic Water exposed by a 6-level step-wedge plan on a Proteus Plus proton system (IBA, Belgium). The calibration doses ranged 65–250 cGy(RBE)more » for proton energies of 170–200MeV. A clinical prostate+nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using one-scan protocol (one-scan digitization of QA film and at least one film exposed to known dose). The Gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film, IBA MatriXX PT, versus TPS calculations were analyzed and compared. Results: The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ∼95% for 2%/2mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. Conclusion: The use of a proton step-wedge for calibration of EBT3 film increases efficiency. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. One author has a research grant from Ashland Inc., the manufacturer of the GafChromic film.« less

[Comparison of radiation dose reduction of prospective ECG-gated one beat scan using 320 area detector CT coronary angiography and prospective ECG-gated helical scan with high helical pitch (FlashScan) using 64 multidetector-row CT coronary angiography].

PubMed

Matsutani, Hideyuki; Sano, Tomonari; Kondo, Takeshi; Fujimoto, Shinichiro; Sekine, Takako; Arai, Takehiro; Morita, Hitomi; Takase, Shinichi

2010-12-20

A high radiation dose associated with 64 multidetector-row computed tomography (64-MDCT) is a major concern for physicians and patients alike. A new 320 row area detector computed tomography (ADCT) can obtain a view of the entire heart with one rotation (0.35 s) without requiring the helical method. As such, ADCT is expected to reduce the radiation dose. We studied image quality and radiation dose of ADCT compared to that of 64-MDCT in patients with a low heart rate (HR≤60). Three hundred eighty-five consecutive patients underwent 64-MDCT and 379 patients, ADCT. Patients with an arrhythmia were excluded. Prospective ECG-gated helical scan with high HP (FlashScan) in 64 was used for MDCT and prospective ECG-gated conventional one beat scan, for 320-ADCT. Image quality was visually evaluated by an image quality score. Radiation dose was estimated by DLP (mGy･cm) for 64-MDCT and DLP.e (mGy･cm) for 320-ADCT. Radiation dose of 320-ADCT (208±48 mGy･cm) was significantly (P<0.0001) lower than that of 64-MDCT (484±112 mGy･cm), and image quality score of 320-ADCT (3.0±0.2) was significantly (P=0.0011) higher than that of 64-MDCT (2.9±0.4). Scan time of 320-ADCT (1.4±0.1 s) was also significantly (P<0.0001) shorter than that of 64-MDCT (6.8±0.6 s). 320-ADCT can achieve not only a reduction in radiation dose but also a superior image quality and shortening of scan time compared to 64-MDCT.

Intermittent impact dynamics of a cantilever scanning a surface at high speed

NASA Astrophysics Data System (ADS)

Dey, S.; Kartik, V.

2018-03-01

In contact-mode scanning probe microscopy (SPM), the cantilever's dynamics are conventionally investigated by assuming the tip to be always in contact with the sample's surface. At high scanning speeds, however, the cantilever's inertia becomes dominant and the tip can therefore completely detach from the surface and start impacting upon it. Experiments at the macro-scale cannot emulate the complex micro-scale dynamics, as the system exhibits negligible effects due to meniscus forces and the surrounding medium's squeeze film damping; however, they can provide qualitative insight into the cantilever's dynamics at high frequencies, corresponding to those likely to be excited during video-rate SPM imaging. This paper investigates such intermittent impact dynamics for an upscaled cantilever, analytically, numerically, and experimentally. In contact-mode scanning, a critical scan speed exists beyond which the cantilever's tip loses contact with the sample's surface; a closed-form expression for this contact loss frequency is derived. At high scan speeds, impacts cause the cantilever to switch between different contact regimes: in-, off-, and grazing-contact; within each regime, the system's modal configuration is different. Experimentally-obtained Poincare maps indicate quasi-periodic behaviour at frequencies for which the response is repetitive, as is also predicted by the model. Intermittent impacts excite the sub- and super-harmonics of the excitation frequency, which are related to the natural frequencies of different system configurations based on the "effective" tip-end boundary conditions. The cantilever's response exhibits several phenomena, such as modal transition, beating, grazing, and possible chaotic behaviour, depending upon the relation between the excitation harmonics and the natural frequencies.

Avoiding Resistance Limitations in High-Performance Transparent Supercapacitor Electrodes Based on Large-Area, High-Conductivity PEDOT:PSS Films.

PubMed

Higgins, Thomas M; Coleman, Jonathan N

2015-08-05

This work describes the potential of thin, spray-deposited, large-area poly(3,4-ethylenedioxythiophene)/poly(styrene-4-sulfonate) ( PSS) conducting polymer films for use as transparent supercapacitor electrodes. To facilitate this, we provide a detailed explanation of the factors limiting the performance of such electrodes. These films have a very low optical conductivity of σop = 24 S/cm (at 550 nm), crucial for this application, and a reasonable volumetric capacitance of CV = 41 F/cm(3). Secondary doping with formic acid gives these films a DC conductivity of σDC = 936 S/cm, allowing them to perform both as a transparent conductor/current collector and transparent supercapacitor electrode. Small-area films (A ∼ 1 cm(2)) display measured areal capacitance as high as 1 mF/cm(2), even for reasonably transparent electrodes (T ∼ 80%). However, in real devices, the absolute capacitance will be maximized by increasing the device area. As such, here, we measure the electrode performance as a function of its length and width. We find that the measured areal capacitance falls dramatically with scan rate and sample length but is independent of width. We show that this is because the measured areal capacitance is limited by the electrical resistance of the electrode. We have derived an equation for the measured areal capacitance as a function of scan rate and electrode lateral dimensions that fits the data extremely well up to scan rates of ∼1000 mV/s (corresponding to charge/discharge times > 0.6 s). These results are self-consistent with independent analysis of the electrical and impedance properties of the electrodes. These results can be used to find limiting combinations of electrode length and scan rate, beyond which electrode performance falls dramatically. We use these insights to build large-area (∼100 cm(2)) supercapacitors using electrodes that are 95% transparent, providing a capacitance of ∼12 mF (at 50 mV/s), significantly higher than that of any previously reported transparent supercapacitor.

Investigation of a high speed data handling system for use with multispectral aircraft scanners

NASA Technical Reports Server (NTRS)

Kelly, W. L.; Meredith, B. D.

1978-01-01

A buffer memory data handling technique for use with multispectral aircraft scanners is presented which allows digital data generated at high data rates to be recorded on magnetic tape. A digital memory is used to temporarily store the data for subsequent recording at slower rates during the passive time of the scan line, thereby increasing the maximum data rate recording capability over real-time recording. Three possible implementations are described and the maximum data rate capability is defined in terms of the speed capability of the key hardware components. The maximum data rates can be used to define the maximum ground resolution achievable by a multispectral aircraft scanner using conventional data handling techniques.

Atomic resolution ultrafast scanning tunneling microscope with scan rate breaking the resonant frequency of a quartz tuning fork resonator.

PubMed

Li, Quanfeng; Lu, Qingyou

2011-05-01

We present an ultra-fast scanning tunneling microscope with atomic resolution at 26 kHz scan rate which surpasses the resonant frequency of the quartz tuning fork resonator used as the fast scan actuator. The main improvements employed in achieving this new record are (1) fully low voltage design (2) independent scan control and data acquisition, where the tuning fork (carrying a tip) is blindly driven to scan by a function generator with the scan voltage and tunneling current (I(T)) being measured as image data (this is unlike the traditional point-by-point move and measure method where data acquisition and scan control are switched many times).

Investigation of a Combined Surveying and Scanning Device: The Trimble SX10 Scanning Total Station

PubMed Central

Lachat, Elise; Landes, Tania; Grussenmeyer, Pierre

2017-01-01

Surveying fields from geosciences to infrastructure monitoring make use of a wide range of instruments for accurate 3D geometry acquisition. In many cases, the Terrestrial Laser Scanner (TLS) tends to become an optimal alternative to total station measurements thanks to the high point acquisition rate it offers, but also to ever deeper data processing software functionalities. Nevertheless, traditional surveying techniques are valuable in some kinds of projects. Nowadays, a few modern total stations combine their conventional capabilities with those of a laser scanner in a unique device. The recent Trimble SX10 scanning total station is a survey instrument merging high-speed 3D scanning and the capabilities of an image-assisted total station. In this paper this new instrument is introduced and first compared to state-of-the-art image-assisted total stations. The paper also addresses the topic of various laser scanning projects and the delivered point clouds are compared with those of other TLS. Directly and indirectly georeferenced projects have been carried out and are investigated in this paper, and a polygonal traverse is performed through a building. Comparisons with the results delivered by well-established survey instruments show the reliability of the Trimble SX10 for geodetic work as well as for scanning projects. PMID:28362319

Normal Rates of Neuroradiological Findings in Children with High Functioning Autism

ERIC Educational Resources Information Center

Vasa, Roma A.; Ranta, Marin; Huisman, Thierry A. G. M.; Pinto, Pedro S.; Tillman, Rachael M.; Mostofsky, Stewart H.

2012-01-01

Magnetic resonance imaging (MRI) has been used to analyze highly specific volumetric and morphological features of the brains of individuals with autism spectrum disorder (ASD). To date, there are few comprehensive studies examining the prevalence of neuroradiologic findings seen on routine MRI scans in children with ASD. This study examined the…

Ultrafast-Charging Supercapacitors Based on Corn-Like Titanium Nitride Nanostructures.

PubMed

Yang, Peihua; Chao, Dongliang; Zhu, Changrong; Xia, Xinhui; Zhang, Yongqi; Wang, Xingli; Sun, Peng; Tay, Beng Kang; Shen, Ze Xiang; Mai, Wenjie; Fan, Hong Jin

2016-06-01

Ultrahigh rates realized by ALD-made TiN . The symmetric full-cell supercapacitors deliver a typical capacitance of 20.7 F cm -3 at a scan rate of 1 V s -1 , and retain 4.3 F cm -3 at high rate of 100 V s -1 . The devices can be charged and discharged for 20 000 cycles with negligible capacitance loss and with an ultralow self-discharge current (≈1 μA).

Energy storage mechanism in aqueous fiber-shaped Li-ion capacitors based on aligned hydrogenated-Li4Ti5O12 nanowires.

PubMed

Zhao, Hao; Ma, Xiangwen; Bai, Jinglong; Yang, Zhenyu; Sun, Gengzhi; Zhang, Zhenxing; Pan, Xiaojun; Lan, Wei; Zhou, Jin Yuan; Xie, Erqing

2017-06-22

It is reported that Li ions can contribute a lot to the capacitance of aqueous Li-ion capacitors (LICs), which might be due to the intercalation/de-intercalation processes of Li + ions that also occur at the anodes. However the energy storage mechanism in the aqueous LIC system still requires further proof. In this work, a type of aqueous fiber-shaped LIC has been designed and developed using hydrogenated Li 4 Ti 5 O 12 (H-LTO) anodes, active carbon (AC) cathodes, and LiCl/PVA gel electrolytes with a double-helical structure. The obtained single LTO wire electrode exhibits a high specific capacitance in volume (34.1 F cm -3 ) and superior cycling stabilities (∼100% over 100 000 cycles), both of which are due to the formed amorphous layers at the surface of the electrodes. Moreover, it is found via sweep voltammetry analysis that most of the energy stored in an aqueous fiber-shaped capacitor electrode is attributed to the Li ions' intercalation, whose content exceeds 85% at a low scan rate and gradually decreases with increasing scan rate; while the energy stored by the double electric layers remains almost unchanged with different scan rates. Furthermore, the well-matched wearable fiber-shaped LICs show high capacitive behaviors (18.44 μW h cm -2 ) and superior static/dynamic cycling stabilities. This research would provide some insight into the charge storage mechanism in electrodes in the aqueous system, and give more suggestions to develop high-energy-density fiber-shaped energy storage devices.

Widefield Two-Photon Excitation without Scanning: Live Cell Microscopy with High Time Resolution and Low Photo-Bleaching

PubMed Central

Amor, Rumelo; McDonald, Alison; Trägårdh, Johanna; Robb, Gillian; Wilson, Louise; Abdul Rahman, Nor Zaihana; Dempster, John; Amos, William Bradshaw; Bushell, Trevor J.; McConnell, Gail

2016-01-01

We demonstrate fluorescence imaging by two-photon excitation without scanning in biological specimens as previously described by Hwang and co-workers, but with an increased field size and with framing rates of up to 100 Hz. During recordings of synaptically-driven Ca2+ events in primary rat hippocampal neurone cultures loaded with the fluorescent Ca2+ indicator Fluo-4 AM, we have observed greatly reduced photo-bleaching in comparison with single-photon excitation. This method, which requires no costly additions to the microscope, promises to be useful for work where high time-resolution is required. PMID:26824845

Benchmark studies of the gyro-Landau-fluid code and gyro-kinetic codes on kinetic ballooning modes

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

Tang, T. F.; Lawrence Livermore National Laboratory, Livermore, California 94550; Xu, X. Q.

2016-03-15

A Gyro-Landau-Fluid (GLF) 3 + 1 model has been recently implemented in BOUT++ framework, which contains full Finite-Larmor-Radius effects, Landau damping, and toroidal resonance [Ma et al., Phys. Plasmas 22, 055903 (2015)]. A linear global beta scan has been conducted using the JET-like circular equilibria (cbm18 series), showing that the unstable modes are kinetic ballooning modes (KBMs). In this work, we use the GYRO code, which is a gyrokinetic continuum code widely used for simulation of the plasma microturbulence, to benchmark with GLF 3 + 1 code on KBMs. To verify our code on the KBM case, we first perform the beta scan basedmore » on “Cyclone base case parameter set.” We find that the growth rate is almost the same for two codes, and the KBM mode is further destabilized as beta increases. For JET-like global circular equilibria, as the modes localize in peak pressure gradient region, a linear local beta scan using the same set of equilibria has been performed at this position for comparison. With the drift kinetic electron module in the GYRO code by including small electron-electron collision to damp electron modes, GYRO generated mode structures and parity suggest that they are kinetic ballooning modes, and the growth rate is comparable to the GLF results. However, a radial scan of the pedestal for a particular set of cbm18 equilibria, using GYRO code, shows different trends for the low-n and high-n modes. The low-n modes show that the linear growth rate peaks at peak pressure gradient position as GLF results. However, for high-n modes, the growth rate of the most unstable mode shifts outward to the bottom of pedestal and the real frequency of what was originally the KBMs in ion diamagnetic drift direction steadily approaches and crosses over to the electron diamagnetic drift direction.« less

Combined High-Speed 3D Scalar and Velocity Reconstruction of Hairpin Vortex

NASA Astrophysics Data System (ADS)

Sabatino, Daniel; Rossmann, Tobias; Zhu, Xuanyu; Thorsen, Mary

2017-11-01

The combination of 3D scanning stereoscopic particle image velocimetry (PIV) and 3D Planar Laser Induced Fluorescence (PLIF) is used to create high-speed three-dimensional reconstructions of the scalar and velocity fields of a developing hairpin vortex. The complete description of the regenerating hairpin vortex is needed as transitional boundary layers and turbulent spots are both comprised of and influenced by these vortices. A new high-speed, high power, laser-based imaging system is used which enables both high-speed 3D scanning stereo PIV and PLIF measurements. The experimental system uses a 250 Hz scanning mirror, two high-speed cameras with a 10 kHz frame rate, and a 40 kHz pulsed laser. Individual stereoscopic PIV images and scalar PLIF images are then reconstructed into time-resolved volumetric velocity and scalar data. The results from the volumetric velocity and scalar fields are compared to previous low-speed tomographic PIV data and scalar visualizations to determine the accuracy and fidelity of the high-speed diagnostics. Comparisons between the velocity and scalar field during hairpin development and regeneration are also discussed. Supported by the National Science Foundation under Grant CBET-1531475, Lafayette College,and the McCutcheon Foundation.

Somatotyping using 3D anthropometry: a cluster analysis.

PubMed

Olds, Tim; Daniell, Nathan; Petkov, John; David Stewart, Arthur

2013-01-01

Somatotyping is the quantification of human body shape, independent of body size. Hitherto, somatotyping (including the most popular method, the Heath-Carter system) has been based on subjective visual ratings, sometimes supported by surface anthropometry. This study used data derived from three-dimensional (3D) whole-body scans as inputs for cluster analysis to objectively derive clusters of similar body shapes. Twenty-nine dimensions normalised for body size were measured on a purposive sample of 301 adults aged 17-56 years who had been scanned using a Vitus Smart laser scanner. K-means Cluster Analysis with v-fold cross-validation was used to determine shape clusters. Three male and three female clusters emerged, and were visualised using those scans closest to the cluster centroid and a caricature defined by doubling the difference between the average scan and the cluster centroid. The male clusters were decidedly endomorphic (high fatness), ectomorphic (high linearity), and endo-mesomorphic (a mixture of fatness and muscularity). The female clusters were clearly endomorphic, ectomorphic, and the ecto-mesomorphic (a mixture of linearity and muscularity). An objective shape quantification procedure combining 3D scanning and cluster analysis yielded shape clusters strikingly similar to traditional somatotyping.

Paediatric cerebrovascular CT angiography—towards better image quality

PubMed Central

Thust, Stefanie C.; Chong, Wui Khean Kling; Gunny, Roxana; Mazumder, Asif; Poitelea, Marius; Welsh, Anna; Ederies, Ash

2014-01-01

Background Paediatric cerebrovascular CT angiography (CTA) can be challenging to perform due to variable cardiovascular physiology between different age groups and the risk of movement artefact. This analysis aimed to determine what proportion of CTA at our institution was of diagnostic quality and identify technical factors which could be improved. Materials and methods a retrospective analysis of 20 cases was performed at a national paediatric neurovascular centre assessing image quality with a subjective scoring system and Hounsfield Unit (HU) measurements. Demographic data, contrast dose, flow rate and triggering times were recorded for each patient. Results Using a qualitative scoring system, 75% of studies were found to be of diagnostic quality (n=9 ‘good’, n=6 ‘satisfactory’) and 25% (n=5) were ‘poor’. Those judged subjectively to be poor had arterial contrast density measured at less than 250 HU. Increased arterial opacification was achieved for cases performed with an increased flow rate (2.5-4 mL/s) and higher intravenous contrast dose (2 mL/kg). Triggering was found to be well timed in nine cases, early in four cases and late in seven cases. Of the scans triggered early, 75% were poor. Of the scans triggered late, less (29%) were poor. Conclusions High flow rates (>2.5 mL/s) were a key factor for achieving high quality paediatric cerebrovascular CTA imaging. However, appropriate triggering by starting the scan immediately on contrast opacification of the monitoring vessel plays an important role and could maintain image quality when flow rates were lower. Early triggering appeared more detrimental than late. PMID:25525579

Miniaturized high throughput detection system for capillary array electrophoresis on chip with integrated light emitting diode array as addressed ring-shaped light source.

PubMed

Ren, Kangning; Liang, Qionglin; Mu, Xuan; Luo, Guoan; Wang, Yiming

2009-03-07

A novel miniaturized, portable fluorescence detection system for capillary array electrophoresis (CAE) on a microfluidic chip was developed, consisting of a scanning light-emitting diode (LED) light source and a single point photoelectric sensor. Without charge coupled detector (CCD), lens, fibers and moving parts, the system was extremely simplified. Pulsed driving of the LED significantly increased the sensitivity, and greatly reduced the power consumption and photobleaching effect. The highly integrated system was robust and easy to use. All the advantages realized the concept of a portable micro-total analysis system (micro-TAS), which could work on a single universal serial bus (USB) port. Compared with traditional CAE detecting systems, the current system could scan the radial capillary array with high scanning rate. An 8-channel CAE of fluorescein isothiocyanate (FITC) labeled arginine (Arg) on chip was demonstrated with this system, resulting in a limit of detection (LOD) of 640 amol.

Fourier domain mode locking at 1050 nm for ultra-high-speed optical coherence tomography of the human retina at 236,000 axial scans per second.

PubMed

Huber, R; Adler, D C; Srinivasan, V J; Fujimoto, J G

2007-07-15

A Fourier domain mode-locked (FDML) laser at 1050 nm for ultra-high-speed optical coherence tomography (OCT) imaging of the human retina is demonstrated. Achievable performance, physical limitations, design rules, and scaling principles for FDML operation and component choice in this wavelength range are discussed. The fiber-based FDML laser operates at a sweep rate of 236 kHz over a 63 nm tuning range, with 7 mW average output power. Ultra-high-speed retinal imaging is demonstrated at 236,000 axial scans per second. This represents a speed improvement of approximately10x over typical high-speed OCT systems, paving the way for densely sampled volumetric data sets and new imaging protocols.

Real-Time Integrated Photoacoustic and Ultrasound (PAUS) Imaging System to Guide Interventional Procedures: Ex Vivo Study

PubMed Central

Wei, Chen-Wei; Nguyen, Thu-Mai; Xia, Jinjun; Arnal, Bastien; Wong, Emily Y.; Pelivanov, Ivan M.; O’Donnell, Matthew

2015-01-01

Because of depth-dependent light attenuation, bulky, low-repetition-rate lasers are usually used in most photoacoustic (PA) systems to provide sufficient pulse energies to image at depth within the body. However, integrating these lasers with real-time clinical ultrasound (US) scanners has been problematic because of their size and cost. In this paper, an integrated PA/US (PAUS) imaging system is presented operating at frame rates >30 Hz. By employing a portable, low-cost, low-pulse-energy (~2 mJ/pulse), high-repetition-rate (~1 kHz), 1053-nm laser, and a rotating galvo-mirror system enabling rapid laser beam scanning over the imaging area, the approach is demonstrated for potential applications requiring a few centimeters of penetration. In particular, we demonstrate here real-time (30 Hz frame rate) imaging (by combining multiple single-shot sub-images covering the scan region) of an 18-gauge needle inserted into a piece of chicken breast with subsequent delivery of an absorptive agent at more than 1-cm depth to mimic PAUS guidance of an interventional procedure. A signal-to-noise ratio of more than 35 dB is obtained for the needle in an imaging area 2.8 × 2.8 cm (depth × lateral). Higher frame rate operation is envisioned with an optimized scanning scheme. PMID:25643081

Active eye-tracking for an adaptive optics scanning laser ophthalmoscope

PubMed Central

Sheehy, Christy K.; Tiruveedhula, Pavan; Sabesan, Ramkumar; Roorda, Austin

2015-01-01

We demonstrate a system that combines a tracking scanning laser ophthalmoscope (TSLO) and an adaptive optics scanning laser ophthalmoscope (AOSLO) system resulting in both optical (hardware) and digital (software) eye-tracking capabilities. The hybrid system employs the TSLO for active eye-tracking at a rate up to 960 Hz for real-time stabilization of the AOSLO system. AOSLO videos with active eye-tracking signals showed, at most, an amplitude of motion of 0.20 arcminutes for horizontal motion and 0.14 arcminutes for vertical motion. Subsequent real-time digital stabilization limited residual motion to an average of only 0.06 arcminutes (a 95% reduction). By correcting for high amplitude, low frequency drifts of the eye, the active TSLO eye-tracking system enabled the AOSLO system to capture high-resolution retinal images over a larger range of motion than previously possible with just the AOSLO imaging system alone. PMID:26203370

High-Sensitivity High-Speed X-ray Fluorescence Scanning Cadmium Telluride Detector for Deep-Portion Cancer Diagnosis Utilizing Tungsten-Kα-Excited Gadolinium Mapping

NASA Astrophysics Data System (ADS)

Yanbe, Yutaka; Sato, Eiichi; Chiba, Hiraku; Maeda, Tomoko; Matsushita, Ryo; Oda, Yasuyuki; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira

2013-09-01

X-ray fluorescence (XRF) analysis is useful for mapping various atoms in objects. Bremsstrahlung X-rays with energies beyond tantalum (Ta) K-edge energy 67.4 keV are absorbed effectively using a 100-µm-thick Ta filter, and the filtered X-rays including tungsten (W) Kα rays are absorbed by gadolinium (Gd) atoms in objects. The Gd XRF is then produced from Gd atoms in the objects and is counted by a cadmium telluride (CdTe) detector. Gd Kα photons with a maximum count rate of 1 kilo counts per second are dispersed using a multichannel analyzer, and the number of photons is counted by a counter card. The distance between the CdTe detector and the object is minimized to 40 mm to increase the count rate. The object is scanned using an x-y stage with a velocity of 5.0 mm/s, and Gd mapping are shown on a computer monitor. The scan steps of the x- and y-axes were both 2.5 mm, and the photon-counting time per mapping point was 0.5 s. We obtained Gd XRF images at high contrast, and Gd Kα photons were easily detected from cancerous regions in a nude mouse placed behind a 20-mm-thick poly(methyl methacrylate) plate.

Tropical rain mapping radar on the Space Station

NASA Technical Reports Server (NTRS)

Im, Eastwood; Li, Fuk

1989-01-01

The conceptual design for a tropical rain mapping radar for flight on the manned Space Station is discussed. In this design the radar utilizes a narrow, dual-frequency (9.7 GHz and 24.1 GHz) beam, electronically scanned antenna to achieve high spatial (4 km) and vertical (250 m) resolutions and a relatively large (800 km) cross-track swath. An adaptive scan strategy will be used for better utilization of radar energy and dwell time. Such a system can detect precipitation at rates of up to 100 mm/hr with accuracies of roughly 15 percent. With the proposed space-time sampling strategy, the monthly averaged rainfall rate can be estimated to within 8 percent, which is essential for many climatological studies.

Terrestrial laser scanning observations of geomorphic changes and varying lava lake levels at Erebus volcano, Antarctica

NASA Astrophysics Data System (ADS)

Jones, Laura K.; Kyle, Philip R.; Oppenheimer, Clive; Frechette, Jedediah D.; Okal, Marianne H.

2015-03-01

A Terrestrial Laser Scanning (TLS) instrument was used to image the topography of the Main Crater at Erebus volcano each December in 2008, 2009, and 2010. Our high-spatial resolution TLS scans provide unique insights into annual and decadal scale geomorphic evolution of the summit area when integrated with comparable data collected by an airborne instrument in 2001. We observe both a pattern of subsidence within the Inner Crater of the volcano and an ~ 3 m per-year drop in the lava lake level over the same time period that are suggestive of decreasing overpressure in an underlying magma reservoir. We also scanned the active phonolite lava lake hosted within the Inner Crater, and recorded rapid cyclic fluctuations in the level of the lake. These were sporadically interrupted by minor explosions by bursting gas bubbles at the lake surface. The TLS data permit calculation of lake level rise and fall speeds and associated rates of volumetric change within the lake. These new observations, when considered with prior determinations of rates of lake surface motion and gas output, are indicative of unsteady magma flow in the conduit and its associated variability in gas volume fraction.

Two-Photon Imaging with Diffractive Optical Elements

PubMed Central

Watson, Brendon O.; Nikolenko, Volodymyr; Yuste, Rafael

2009-01-01

Two-photon imaging has become a useful tool for optical monitoring of neural circuits, but it requires high laser power and serial scanning of each pixel in a sample. This results in slow imaging rates, limiting the measurements of fast signals such as neuronal activity. To improve the speed and signal-to-noise ratio of two-photon imaging, we introduce a simple modification of a two-photon microscope, using a diffractive optical element (DOE) which splits the laser beam into several beamlets that can simultaneously scan the sample. We demonstrate the advantages of DOE scanning by enhancing the speed and sensitivity of two-photon calcium imaging of action potentials in neurons from neocortical brain slices. DOE scanning can easily improve the detection of time-varying signals in two-photon and other non-linear microscopic techniques. PMID:19636390

Performance comparison between the high-speed Yokogawa spinning disc confocal system and single-point scanning confocal systems.

PubMed

Wang, E; Babbey, C M; Dunn, K W

2005-05-01

Fluorescence microscopy of the dynamics of living cells presents a special challenge to a microscope imaging system, simultaneously requiring both high spatial resolution and high temporal resolution, but with illumination levels low enough to prevent fluorophore damage and cytotoxicity. We have compared the high-speed Yokogawa CSU10 spinning disc confocal system with several conventional single-point scanning confocal (SPSC) microscopes, using the relationship between image signal-to-noise ratio and fluorophore photobleaching as an index of system efficiency. These studies demonstrate that the efficiency of the CSU10 consistently exceeds that of the SPSC systems. The high efficiency of the CSU10 means that quality images can be collected with much lower levels of illumination; the CSU10 was capable of achieving the maximum signal-to-noise of an SPSC system at illumination levels that incur only at 1/15th of the rate of the photobleaching of the SPSC system. Although some of the relative efficiency of the CSU10 system may be attributed to the use of a CCD rather than a photomultiplier detector system, our analyses indicate that high-speed imaging with the SPSC system is limited by fluorescence saturation at the high levels of illumination frequently needed to collect images at high frame rates. The high speed, high efficiency and freedom from fluorescence saturation combine to make the CSU10 effective for extended imaging of living cells at rates capable of capturing the three-dimensional motion of endosomes moving up to several micrometres per second.

FPGA Based Adaptive Rate and Manifold Pattern Projection for Structured Light 3D Camera System †

PubMed Central

Lee, Sukhan

2018-01-01

The quality of the captured point cloud and the scanning speed of a structured light 3D camera system depend upon their capability of handling the object surface of a large reflectance variation in the trade-off of the required number of patterns to be projected. In this paper, we propose and implement a flexible embedded framework that is capable of triggering the camera single or multiple times for capturing single or multiple projections within a single camera exposure setting. This allows the 3D camera system to synchronize the camera and projector even for miss-matched frame rates such that the system is capable of projecting different types of patterns for different scan speed applications. This makes the system capturing a high quality of 3D point cloud even for the surface of a large reflectance variation while achieving a high scan speed. The proposed framework is implemented on the Field Programmable Gate Array (FPGA), where the camera trigger is adaptively generated in such a way that the position and the number of triggers are automatically determined according to camera exposure settings. In other words, the projection frequency is adaptive to different scanning applications without altering the architecture. In addition, the proposed framework is unique as it does not require any external memory for storage because pattern pixels are generated in real-time, which minimizes the complexity and size of the application-specific integrated circuit (ASIC) design and implementation. PMID:29642506

Targeting regional pediatric congenital hearing loss using a spatial scan statistic.

PubMed

Bush, Matthew L; Christian, Warren Jay; Bianchi, Kristin; Lester, Cathy; Schoenberg, Nancy

2015-01-01

Congenital hearing loss is a common problem, and timely identification and intervention are paramount for language development. Patients from rural regions may have many barriers to timely diagnosis and intervention. The purpose of this study was to examine the spatial and hospital-based distribution of failed infant hearing screening testing and pediatric congenital hearing loss throughout Kentucky. Data on live births and audiological reporting of infant hearing loss results in Kentucky from 2009 to 2011 were analyzed. The authors used spatial scan statistics to identify high-rate clusters of failed newborn screening tests and permanent congenital hearing loss (PCHL), based on the total number of live births per county. The authors conducted further analyses on PCHL and failed newborn hearing screening tests, based on birth hospital data and method of screening. The authors observed four statistically significant (p < 0.05) high-rate clusters with failed newborn hearing screenings in Kentucky, including two in the Appalachian region. Hospitals using two-stage otoacoustic emission testing demonstrated higher rates of failed screening (p = 0.009) than those using two-stage automated auditory brainstem response testing. A significant cluster of high rate of PCHL was observed in Western Kentucky. Five of the 54 birthing hospitals were found to have higher relative risk of PCHL, and two of those hospitals are located in a very rural region of Western Kentucky within the cluster. This spatial analysis in children in Kentucky has identified specific regions throughout the state with high rates of congenital hearing loss and failed newborn hearing screening tests. Further investigation regarding causative factors is warranted. This method of analysis can be useful in the setting of hearing health disparities to focus efforts on regions facing high incidence of congenital hearing loss.

Supercapacitors based on nitrogen-doped reduced graphene oxide and borocarbonitrides

NASA Astrophysics Data System (ADS)

Gopalakrishnan, K.; Moses, Kota; Govindaraj, A.; Rao, C. N. R.

2013-12-01

Nitrogen-doped reduced graphene oxide (RGO) samples with different nitrogen content, prepared by two different methods, as well as nitrogen-doped few-layer graphene have been investigated as supercapacitor electrodes. Two electrode measurements have been carried out both in aqueous (6M KOH) and in ionic liquid media. Nitrogen-doped reduced graphene oxides exhibit satisfactory specific capacitance, the values reaching 126F/g at a scan rate of 10mV/s in aqueous medium. Besides providing supercapacitor characteristics, the study has shown the nitrogen content and surface area to be important factors. High surface-area borocarbonitrides, BxCyNz, prepared by the urea route appear to be excellent supercapacitor electrode materials. Thus, BC4.5N exhibits a specific capacitance of 169F/g at a scan rate of 10mV/s in aqueous medium. In an ionic liquid medium, nitrogen-doped RGO and BC4.5N exhibit specific capacitance values of 258F/g and 240F/g at a scan rate of 5mV/s. The ionic liquid enables a larger operating voltage range of 0.0-2.5V compared to 0.0-1V in aqueous medium.

Patient-Specific QA of Spot-Scanning Proton Beams using Radiochromic Film.

PubMed

Chan, Maria F; Chen, Chin-Cheng; Shi, Chengyu; Li, Jingdong; Tang, Xiaoli; Li, Xiang; Mah, Dennis

2017-05-01

Radiochromic film for spot-scanning QA provides high spatial resolution and efficiency gains from one-shot irradiation for multiple depths. However, calibration can be a tedious procedure which may limit widespread use. Moreover, since there may be an energy dependence, which manifests as a depth dependence, this may require additional measurements for each patient. We present a one-scan protocol to simplify the procedure. A calibration using an EBT3 film, exposed by a 6-level step-wedge plan on a Proteus ® PLUS proton system (IBA, Belgium), was performed at depths of 18, 20, 24cm using Plastic Water ® (CIRS, Norfolk, VA). The calibration doses ranged from 65-250 cGy(RBE) (relative biological effectiveness) for proton energies of 170-200 MeV. A clinical prostate+nodes plan was used for validation. The planar doses at selected depths were measured with EBT3 films and analyzed using One-scan protocol (one-scan digitization of QA film and at least one film exposed to a known dose). The gamma passing rates, dose-difference maps, and profiles of 2D planar doses measured with EBT3 film and IBA MatriXX-PT, versus the RayStation TPS calculations were analyzed and compared. The EBT3 film measurement results matched well with the TPS calculation data with an average passing rate of ~95% for 2%/2mm and slightly lower passing rates were obtained from an ion chamber array detector. We were able to demonstrate that the use of a proton step-wedge provided clinically acceptable results and minimized variations between film-scanner orientation, inter-scan, and scanning conditions. Furthermore, for relative dosimetry (calibration is not done at the time of experiment) it could be derived from no more than two films exposed to known doses (one could be zero) for rescaling the master calibration curve at each depth. The sensitivity of the calibration to depth variations has been explored. One-scan protocol results appear to be comparable to that of the ion chamber array detector. The use of a proton step-wedge for calibration of EBT3 film potentially increases efficiency in patient-specific QA of proton beams.

[Microcosmic mechanisms of amorphous indomethacin crystallization and the influence of nano-coating on crystallization].

PubMed

Hui, Ou-Yang; Yi, Tao; Zheng, Qin; Liu, Feng

2011-06-01

Amorphous drugs have higher solubility, better oral bioavailability and are easier to be absorbed than their crystalline counterparts. However, the amorphous drugs, with weak stability, are so easy to crystallize that they will lose the original advantages. Polarization microscope, scanning electron microscope, differential scanning calorimetry, X-ray diffractomer and Raman spectroscopy were used to study the microcosmic crystallization mechanisms of amorphous indometacin and the performance of the drug crystals. The results showed that the growth rate of amorphous indometacin crystals at the free surface was markedly faster than that through the bulk, and that the crystal growth rate decreased observably after spraying an ultrathin melting gold (10 nm) at the free surface of the drug. These results indicated that the high growth rates of amorphous drugs crystals at the free surface were the key to their stability and that an ultrathin coating could be applied to enhance the stability of amorphous drugs.

Processing Parameters Optimization for Material Deposition Efficiency in Laser Metal Deposited Titanium Alloy

NASA Astrophysics Data System (ADS)

Mahamood, Rasheedat M.; Akinlabi, Esther T.

2016-03-01

Ti6Al4V is an important Titanium alloy that is mostly used in many applications such as: aerospace, petrochemical and medicine. The excellent corrosion resistance property, the high strength to weight ratio and the retention of properties at high temperature makes them to be favoured in most applications. The high cost of Titanium and its alloys makes their use to be prohibitive in some applications. Ti6Al4V can be cladded on a less expensive material such as steel, thereby reducing cost and providing excellent properties. Laser Metal Deposition (LMD) process, an additive manufacturing process is capable of producing complex part directly from the 3-D CAD model of the part and it also has the capability of handling multiple materials. Processing parameters play an important role in LMD process and in order to achieve desired results at a minimum cost, then the processing parameters need to be properly controlled. This paper investigates the role of processing parameters: laser power, scanning speed, powder flow rate and gas flow rate, on the material utilization efficiency in laser metal deposited Ti6Al4V. A two-level full factorial design of experiment was used in this investigation, to be able to understand the processing parameters that are most significant as well as the interactions among these processing parameters. Four process parameters were used, each with upper and lower settings which results in a combination of sixteen experiments. The laser power settings used was 1.8 and 3 kW, the scanning speed was 0.05 and 0.1 m/s, the powder flow rate was 2 and 4 g/min and the gas flow rate was 2 and 4 l/min. The experiments were designed and analyzed using Design Expert 8 software. The software was used to generate the optimized process parameters which were found to be laser power of 3.2 kW, scanning speed of 0.06 m/s, powder flow rate of 2 g/min and gas flow rate of 3 l/min.

Fiber-based all-solid-state flexible supercapacitors for self-powered systems.

PubMed

Xiao, Xu; Li, Tianqi; Yang, Peihua; Gao, Yuan; Jin, Huanyu; Ni, Weijian; Zhan, Wenhui; Zhang, Xianghui; Cao, Yuanzhi; Zhong, Junwen; Gong, Li; Yen, Wen-Chun; Mai, Wenjie; Chen, Jian; Huo, Kaifu; Chueh, Yu-Lun; Wang, Zhong Lin; Zhou, Jun

2012-10-23

All-solid-state flexible supercapacitors based on a carbon/MnO(2) (C/M) core-shell fiber structure were fabricated with high electrochemical performance such as high rate capability with a scan rate up to 20 V s(-1), high volume capacitance of 2.5 F cm(-3), and an energy density of 2.2 × 10(-4) Wh cm(-3). By integrating with a triboelectric generator, supercapacitors could be charged and power commercial electronic devices, such as a liquid crystal display or a light-emitting-diode, demonstrating feasibility as an efficient storage component and self-powered micro/nanosystems.

See-Through Imaging of Laser-Scanned 3d Cultural Heritage Objects Based on Stochastic Rendering of Large-Scale Point Clouds

NASA Astrophysics Data System (ADS)

Tanaka, S.; Hasegawa, K.; Okamoto, N.; Umegaki, R.; Wang, S.; Uemura, M.; Okamoto, A.; Koyamada, K.

2016-06-01

We propose a method for the precise 3D see-through imaging, or transparent visualization, of the large-scale and complex point clouds acquired via the laser scanning of 3D cultural heritage objects. Our method is based on a stochastic algorithm and directly uses the 3D points, which are acquired using a laser scanner, as the rendering primitives. This method achieves the correct depth feel without requiring depth sorting of the rendering primitives along the line of sight. Eliminating this need allows us to avoid long computation times when creating natural and precise 3D see-through views of laser-scanned cultural heritage objects. The opacity of each laser-scanned object is also flexibly controllable. For a laser-scanned point cloud consisting of more than 107 or 108 3D points, the pre-processing requires only a few minutes, and the rendering can be executed at interactive frame rates. Our method enables the creation of cumulative 3D see-through images of time-series laser-scanned data. It also offers the possibility of fused visualization for observing a laser-scanned object behind a transparent high-quality photographic image placed in the 3D scene. We demonstrate the effectiveness of our method by applying it to festival floats of high cultural value. These festival floats have complex outer and inner 3D structures and are suitable for see-through imaging.

Performance of High Layer Thickness in Selective Laser Melting of Ti6Al4V

PubMed Central

Shi, Xuezhi; Ma, Shuyuan; Liu, Changmeng; Chen, Cheng; Wu, Qianru; Chen, Xianping; Lu, Jiping

2016-01-01

To increase building rate and save cost, the selective laser melting (SLM) of Ti6Al4V with a high layer thickness (200 μm) and low cost coarse powders (53 μm–106 μm) at a laser power of 400 W is investigated in this preliminary study. A relatively large laser beam with a diameter of 200 μm is utilized to produce a stable melt pool at high layer thickness, and the appropriate scanning track, which has a smooth surface with a shallow contact angle, can be obtained at the scanning speeds from 40 mm/s to 80 mm/s. By adjusting the hatch spacings, the density of multi-layer samples can be up to 99.99%, which is much higher than that achieved in previous studies about high layer thickness selective laser melting. Meanwhile, the building rate can be up to 7.2 mm3/s, which is about 2 times–9 times that of the commercial equipment. Besides, two kinds of defects are observed: the large un-melted defects and the small spherical micropores. The formation of the un-melted defects is mainly attributed to the inappropriate overlap rates and the unstable scanning tracks, which can be eliminated by adjusting the processing parameters. Nevertheless, the micropores cannot be completely eliminated. It is worth noting that the high layer thickness plays a key role on surface roughness rather than tensile properties during the SLM process. Although a sample with a relatively coarse surface is generated, the average values of yield strength, ultimate tensile strength, and elongation are 1050 MPa, 1140 MPa, and 7.03%, respectively, which are not obviously different than those with the thin layer thickness used in previous research; this is due to the similar metallurgical bonding and microstructure. PMID:28774097

Evaluation of a laser scanning sensor for variable-rate tree sprayer development

USDA-ARS?s Scientific Manuscript database

Accurate canopy measurement capabilities are prerequisites to automate variable-rate sprayers. A 270° radial range laser scanning sensor was tested for its scanning accuracy to detect tree canopy profiles. Signals from the laser sensor and a ground speed sensor were processed with an embedded comput...

cnvScan: a CNV screening and annotation tool to improve the clinical utility of computational CNV prediction from exome sequencing data.

PubMed

Samarakoon, Pubudu Saneth; Sorte, Hanne Sørmo; Stray-Pedersen, Asbjørg; Rødningen, Olaug Kristin; Rognes, Torbjørn; Lyle, Robert

2016-01-14

With advances in next generation sequencing technology and analysis methods, single nucleotide variants (SNVs) and indels can be detected with high sensitivity and specificity in exome sequencing data. Recent studies have demonstrated the ability to detect disease-causing copy number variants (CNVs) in exome sequencing data. However, exonic CNV prediction programs have shown high false positive CNV counts, which is the major limiting factor for the applicability of these programs in clinical studies. We have developed a tool (cnvScan) to improve the clinical utility of computational CNV prediction in exome data. cnvScan can accept input from any CNV prediction program. cnvScan consists of two steps: CNV screening and CNV annotation. CNV screening evaluates CNV prediction using quality scores and refines this using an in-house CNV database, which greatly reduces the false positive rate. The annotation step provides functionally and clinically relevant information using multiple source datasets. We assessed the performance of cnvScan on CNV predictions from five different prediction programs using 64 exomes from Primary Immunodeficiency (PIDD) patients, and identified PIDD-causing CNVs in three individuals from two different families. In summary, cnvScan reduces the time and effort required to detect disease-causing CNVs by reducing the false positive count and providing annotation. This improves the clinical utility of CNV detection in exome data.

A photon-counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location.

[Preoperative CT Scan in middle ear cholesteatoma].

PubMed

Sethom, Anissa; Akkari, Khemaies; Dridi, Inès; Tmimi, S; Mardassi, Ali; Benzarti, Sonia; Miled, Imed; Chebbi, Mohamed Kamel

2011-03-01

To compare preoperative CT scan finding and per-operative lesions in patients operated for middle ear cholesteatoma, A retrospective study including 60 patients with cholesteatoma otitis diagnosed and treated within a period of 5 years, from 2001 to 2005, at ENT department of Military Hospital of Tunis. All patients had computed tomography of the middle and inner ear. High resolution CT scan imaging was performed using millimetric incidences (3 to 5 millimetres). All patients had surgical removal of their cholesteatoma using down wall technic. We evaluated sensitivity, specificity and predictive value of CT-scan comparing otitic damages and CT finding, in order to examine the real contribution of computed tomography in cholesteatoma otitis. CT scan analysis of middle ear bone structures shows satisfaction (with 83% of sensibility). The rate of sensibility decrease (63%) for the tympanic raff. Predictive value of CT scan for the diagnosis of cholesteatoma was low. However, we have noticed an excellent sensibility in the analysis of ossicular damages (90%). Comparative frontal incidence seems to be less sensible for the detection of facial nerve lesions (42%). But when evident on CT scan findings, lesions of facial nerve were usually observed preoperatively (spécificity 78%). Predictive value of computed tomography for the diagnosis of perilymphatic fistulae (FL) was low. In fact, CT scan imaging have showed FL only for four patients among eight. Best results can be obtained if using inframillimetric incidences with performed high resolution computed tomography. Preoperative computed tomography is necessary for the diagnosis and the evaluation of chronic middle ear cholesteatoma in order to show extending lesion and to detect complications. This CT analysis and surgical correlation have showed that sensibility, specificity and predictive value of CT-scan depend on the anatomic structure implicated in cholesteatoma damages.

FPGA-based real-time swept-source OCT systems for B-scan live-streaming or volumetric imaging

NASA Astrophysics Data System (ADS)

Bandi, Vinzenz; Goette, Josef; Jacomet, Marcel; von Niederhäusern, Tim; Bachmann, Adrian H.; Duelk, Marcus

2013-03-01

We have developed a Swept-Source Optical Coherence Tomography (Ss-OCT) system with high-speed, real-time signal processing on a commercially available Data-Acquisition (DAQ) board with a Field-Programmable Gate Array (FPGA). The Ss-OCT system simultaneously acquires OCT and k-clock reference signals at 500MS/s. From the k-clock signal of each A-scan we extract a remap vector for the k-space linearization of the OCT signal. The linear but oversampled interpolation is followed by a 2048-point FFT, additional auxiliary computations, and a data transfer to a host computer for real-time, live-streaming of B-scan or volumetric C-scan OCT visualization. We achieve a 100 kHz A-scan rate by parallelization of our hardware algorithms, which run on standard and affordable, commercially available DAQ boards. Our main development tool for signal analysis as well as for hardware synthesis is MATLAB® with add-on toolboxes and 3rd-party tools.

Alternating current scanning electrochemical microscopy with simultaneous fast-scan cyclic voltammetry.

PubMed

Koch, Jason A; Baur, Melinda B; Woodall, Erica L; Baur, John E

2012-11-06

Fast-scan cyclic voltammetry (FSCV) is combined with alternating current scanning electrochemical microscopy (AC-SECM) for simultaneous measurements of impedance and faradaic current. Scan rates of 10-1000 V s(-1) were used for voltammetry, while a high-frequency (100 kHz), low-amplitude (10 mV rms) sine wave was added to the voltammetric waveform for the ac measurement. Both a lock-in amplifier and an analog circuit were used to measure the amplitude of the resultant ac signal. The effect of the added sine wave on the voltammetry at a carbon fiber electrode was investigated and found to have negligible effect. The combined FSCV and ac measurements were used to provide simultaneous chemical and topographical information about a substrate using a single carbon fiber probe. The technique is demonstrated in living cell culture, where cellular respiration and topography were simultaneously imaged without the addition of a redox mediator. This approach promises to be useful for the topographical and multidimensional chemical imaging of substrates.

An integrated approach to piezoactuator positioning in high-speed atomic force microscope imaging

NASA Astrophysics Data System (ADS)

Yan, Yan; Wu, Ying; Zou, Qingze; Su, Chanmin

2008-07-01

In this paper, an integrated approach to achieve high-speed atomic force microscope (AFM) imaging of large-size samples is proposed, which combines the enhanced inversion-based iterative control technique to drive the piezotube actuator control for lateral x-y axis positioning with the use of a dual-stage piezoactuator for vertical z-axis positioning. High-speed, large-size AFM imaging is challenging because in high-speed lateral scanning of the AFM imaging at large size, large positioning error of the AFM probe relative to the sample can be generated due to the adverse effects—the nonlinear hysteresis and the vibrational dynamics of the piezotube actuator. In addition, vertical precision positioning of the AFM probe is even more challenging (than the lateral scanning) because the desired trajectory (i.e., the sample topography profile) is unknown in general, and the probe positioning is also effected by and sensitive to the probe-sample interaction. The main contribution of this article is the development of an integrated approach that combines advanced control algorithm with an advanced hardware platform. The proposed approach is demonstrated in experiments by imaging a large-size (50μm ) calibration sample at high-speed (50Hz scan rate).

Resonant Scanning with Large Field of View Reduces Photobleaching and Enhances Fluorescence Yield in STED Microscopy.

PubMed

Wu, Yong; Wu, Xundong; Lu, Rong; Zhang, Jin; Toro, Ligia; Stefani, Enrico

2015-10-01

Photobleaching is a major limitation of superresolution Stimulated Depletion Emission (STED) microscopy. Fast scanning has long been considered an effective means to reduce photobleaching in fluorescence microscopy, but a careful quantitative study of this issue is missing. In this paper, we show that the photobleaching rate in STED microscopy can be slowed down and the fluorescence yield be enhanced by scanning with high speed, enabled by using large field of view in a custom-built resonant-scanning STED microscope. The effect of scanning speed on photobleaching and fluorescence yield is more remarkable at higher levels of depletion laser irradiance, and virtually disappears in conventional confocal microscopy. With ≥6 GW∙cm(-2) depletion irradiance, we were able to extend the fluorophore survival time of Atto 647N and Abberior STAR 635P by ~80% with 8-fold wider field of view. We confirm that STED Photobleaching is primarily caused by the depletion light acting upon the excited fluorophores. Experimental data agree with a theoretical model. Our results encourage further increasing the linear scanning speed for photobleaching reduction in STED microscopy.

Ultrafast photon counting applied to resonant scanning STED microscopy.

PubMed

Wu, Xundong; Toro, Ligia; Stefani, Enrico; Wu, Yong

2015-01-01

To take full advantage of fast resonant scanning in super-resolution stimulated emission depletion (STED) microscopy, we have developed an ultrafast photon counting system based on a multigiga sample per second analogue-to-digital conversion chip that delivers an unprecedented 450 MHz pixel clock (2.2 ns pixel dwell time in each scan). The system achieves a large field of view (∼50 × 50 μm) with fast scanning that reduces photobleaching, and advances the time-gated continuous wave STED technology to the usage of resonant scanning with hardware-based time-gating. The assembled system provides superb signal-to-noise ratio and highly linear quantification of light that result in superior image quality. Also, the system design allows great flexibility in processing photon signals to further improve the dynamic range. In conclusion, we have constructed a frontier photon counting image acquisition system with ultrafast readout rate, excellent counting linearity, and with the capacity of realizing resonant-scanning continuous wave STED microscopy with online time-gated detection. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

Supersonic molecular beam-hyperthermal surface ionisation coupled with time-of-flight mass spectrometry applied to trace level detection of polynuclear aromatic hydrocarbons in drinking water for reduced sample preparation and analysis time.

PubMed

Davis, S C; Makarov, A A; Hughes, J D

1999-01-01

Analysis of sub-ppb levels of polynuclear aromatic hydrocarbons (PAHs) in drinking water by high performance liquid chromatography (HPLC) fluorescence detection typically requires large water samples and lengthy extraction procedures. The detection itself, although selective, does not give compound identity confirmation. Benchtop gas chromatography/mass spectrometry (GC/MS) systems operating in the more sensitive selected ion monitoring (SIM) acquisition mode discard spectral information and, when operating in scanning mode, are less sensitive and scan too slowly. The selectivity of hyperthermal surface ionisation (HSI), the high column flow rate capacity of the supersonic molecular beam (SMB) GC/MS interface, and the high acquisition rate of time-of-flight (TOF) mass analysis, are combined here to facilitate a rapid, specific and sensitive technique for the analysis of trace levels of PAHs in water. This work reports the advantages gained by using the GC/HSI-TOF system over the HPLC fluorescence method, and discusses in some detail the nature of the instrumentation used.

High precision tracking of a piezoelectric nano-manipulator with parameterized hysteresis compensation

NASA Astrophysics Data System (ADS)

Yan, Peng; Zhang, Yangming

2018-06-01

High performance scanning of nano-manipulators is widely deployed in various precision engineering applications such as SPM (scanning probe microscope), where trajectory tracking of sophisticated reference signals is an challenging control problem. The situation is further complicated when rate dependent hysteresis of the piezoelectric actuators and the stress-stiffening induced nonlinear stiffness of the flexure mechanism are considered. In this paper, a novel control framework is proposed to achieve high precision tracking of a piezoelectric nano-manipulator subjected to hysteresis and stiffness nonlinearities. An adaptive parameterized rate-dependent Prandtl-Ishlinskii model is constructed and the corresponding adaptive inverse model based online compensation is derived. Meanwhile a robust adaptive control architecture is further introduced to improve the tracking accuracy and robustness of the compensated system, where the parametric uncertainties of the nonlinear dynamics can be well eliminated by on-line estimations. Comparative experimental studies of the proposed control algorithm are conducted on a PZT actuated nano-manipulating stage, where hysteresis modeling accuracy and excellent tracking performance are demonstrated in real-time implementations, with significant improvement over existing results.

18F-FDG uptake and its clinical relevance in primary gastric lymphoma.

PubMed

Yi, Jun Ho; Kim, Seok Jin; Choi, Joon Young; Ko, Young Hyeh; Kim, Byung-Tae; Kim, Won Seog

2010-06-01

We studied the clinical relevance of (18)F-fluorodeoxyglucose ((18)F-FDG) uptake in patients with primary gastric lymphoma underwent positron emission tomography (PET)/ computed tomography (CT) scan. Forty-two patients with primary gastric lymphoma were analysed: 32 diffuse large B-cell lymphomas (DLBCL) and 10 extranodal marginal zone B-cell lymphomas of mucosa-associated lymphoid tissue (MALT lymphomas). The PET/CT scans were compared with clinical and pathologic features, and the results of CT and endoscopy. Nine patients were up-staged based on the results of their PET/CT scan compared to CT (seven DLBCLs, two MALT lymphomas) while six patients were down-staged by the PET/CT scan. The standard uptake value (SUV) was used as an indicator of a lesion with a high metabolic rate. The high SUVmax group, defined as an SUVmax >or= median value, was significantly associated with an advanced Lugano stage (p < 0.001). Three patients with DLBCL, who showed an initially high SUVmax, died of disease progression. Among 24 patients for whom follow-up PET/CT scan with endoscopy was performed, 11 patients with ulcerative or mucosal lesions showed residual (18)F-FDG uptake. All of these gastric lesions were grossly and pathologically benign lesions without evidence of lymphoma cells. In conclusion, PET/CT scan can be used in staging patients with primary gastric lymphoma; however, the residual (18)F-FDG uptake observed during follow-up should be interpreted cautiously and should be combined with endoscopy and multiple biopsies of the stomach. (c) 2009 John Wiley & Sons, Ltd.

High-speed bioimaging with frequency-division-multiplexed fluorescence confocal microscopy

NASA Astrophysics Data System (ADS)

Mikami, Hideharu; Harmon, Jeffrey; Ozeki, Yasuyuki; Goda, Keisuke

2017-04-01

We present methods of fluorescence confocal microscopy that enable unprecedentedly high frame rate of > 10,000 fps. The methods are based on a frequency-division multiplexing technique, which was originally developed in the field of communication engineering. Specifically, we achieved a broad bandwidth ( 400 MHz) of detection signals using a dual- AOD method and overcame limitations in frame rate, due to a scanning device, by using a multi-line focusing method, resulting in a significant increase in frame rate. The methods have potential biomedical applications such as observation of sub-millisecond dynamics in biological tissues, in-vivo three-dimensional imaging, and fluorescence imaging flow cytometry.

Enthalpy and high temperature relaxation kinetics of stable vapor-deposited glasses of toluene

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

Bhattacharya, Deepanjan; Sadtchenko, Vlad, E-mail: vlad@gwu.edu

Stable non-crystalline toluene films of micrometer and nanometer thicknesses were grown by vapor deposition at distinct rates and probed by fast scanning calorimetry. Fast scanning calorimetry is shown to be extremely sensitive to the structure of the vapor-deposited phase and was used to characterize simultaneously its kinetic stability and its thermodynamic properties. According to our analysis, transformation of vapor-deposited samples of toluene during heating with rates in excess 10{sup 5} K s{sup −1} follows the zero-order kinetics. The transformation rate correlates strongly with the initial enthalpy of the sample, which increases with the deposition rate according to sub-linear law. Analysismore » of the transformation kinetics of vapor-deposited toluene films of various thicknesses reveal a sudden increase in the transformation rate for films thinner than 250 nm. The change in kinetics seems to correlate with the surface roughness scale of the substrate. The implications of these findings for the formation mechanism and structure of vapor-deposited stable glasses are discussed.« less

Rain core structure statistics derived from radar and disdrometer measurements in the mid-Atlantic coast of the US

NASA Technical Reports Server (NTRS)

Goldhirsh, Julius; Musiani, Bert H.

1989-01-01

During a period spanning more than 5 years, low elevation radar measurements of rain were systematically obtained in the mid-Atlantic coast of the U.S. Drop size distribution measurements with a disdrometer were also acquired on the same rain days. The drop size data were utilized to convert the radar reflectivity factors to estimated rain rates for the respective rain days of operation. Applying high level algorithms to the rain data, core values of rain intensities were identified (peak rain rates), and families of rain rate isopleths analyzed. In particular, equicircle diameters of the family of isopleths enveloping peak rain intensities were statistically characterized. The presented results represents the analysis of two rain days, 12 radar scans, corresponding to 430 culled rain rate isopleths from an available data base of 22,000 contours, approximately 100 scans encompassing 17 rain days. The results presented show trends of the average rain rate vs. contour scale dimensions, and cumulative distributions of rain cell dimensions which belong to core families of precipitation.

Adenine-functionalized Spongy Graphene for Green and High-Performance Supercapacitors

PubMed Central

El-Gendy, Dalia M.; Ghany, Nabil A. Abdel; El Sherbini, E. E. Foad; Allam, Nageh K.

2017-01-01

A simple method is demonstrated to prepare spongy adenine-functionalized graphene (SFG) as interconnected, porous 3-dimensional (3D) network crinkly sheets. Such 3D network structure provides better contact at the electrode/electrolyte interface and facilitates the charge transfer kinetics. The fabricated SFG was characterized by X-ray diffraction (XRD), FTIR, scanning electron microscopy (FESEM), Raman spectroscopy, thermogravimetric analysis (TGA), UV−vis absorption spectroscopy, and transmission electron microscopy (TEM). The synthesized materials have been evaluated as supercapacitor materials in 0.5 M H2SO4 using cyclic voltammetry (CV) at different potential scan rates, and galvanostatic charge/discharge tests at different current densities. The SFG electrodes showed a maximum specific capacitance of 333 F/g at scan rate of 1 mV/s and exhibited excellent cycling retention of 102% after 1000 cycles at 200 mV/s. The energy density was 64.42 Wh/kg with a power density of 599.8 W/kg at 1.0 A/g. Those figures of merit are much higher than those reported for graphene-based materials tested under similar conditions. The observed high performance can be related to the synergistic effects of the spongy structure and the adenine functionalization. PMID:28216668

Copernicus ultraviolet spectra of OB supergiants with strong stellar winds

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

Hutchings, J.B.

1976-03-01

Spectral scans at approximately 0.2 A resolution have been obtained in the far-ultraviolet of eight stars which have high mass-loss rates from stellar winds. The P Cygni characteristics of the line profiles appear to vary inversely as the mass flow rate, and in P Cygni itself the C III lambda 1175 line shows no velocity shift, or emission. It is suggested that higher mass flow rates occur through a denser, slower moving envelope in which collisional interactions are important. (auth)

Solid-state optical microscope

DOEpatents

Young, I.T.

1981-01-07

A solid state optical microscope is described wherein wide-field and high-resolution images of an object are produced at a rapid rate by utilizing conventional optics with a charge-coupled photodiode array. Means for scanning in one of two orthogonal directions are provided, while the charge-coupled photodiode array scans in the other orthogonal direction. Illumination light from the object is incident upon the photodiodes, creating packets of electrons (signals) which are representative of the illuminated object. The signals are then processed, stored in a memory, and finally displayed as a video signal.

Electrodeposited manganese dioxide nanostructures on electro-etched carbon fibers: High performance materials for supercapacitor applications

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

Kazemi, Sayed Habib, E-mail: habibkazemi@iasbs.ac.ir; Center for Research in Climate Change and Global Warming; Maghami, Mostafa Ghaem

Highlights: • We report a facile method for fabrication of MnO{sub 2} nanostructures on electro-etched carbon fiber. • MnO{sub 2}-ECF electrode shows outstanding supercapacitive behavior even at high discharge rates. • Exceptional cycle stability was achieved for MnO{sub 2}-ECF electrode. • The coulombic efficiency of MnO{sub 2}-ECF electrode is nearly 100%. - Abstract: In this article we introduce a facile, low cost and additive/template free method to fabricate high-rate electrochemical capacitors. Manganese oxide nanostructures were electrodeposited on electro-etched carbon fiber substrate by applying a constant anodic current. Nanostructured MnO{sub 2} on electro-etched carbon fiber was characterized by scanning electron microscopy,more » X-ray diffraction and energy dispersive X-ray analysis. The electrochemical behavior of MnO{sub 2} electro-etched carbon fiber electrode was investigated by electrochemical techniques including cyclic voltammetry, galvanostatic charge/discharge, and electrochemical impedance spectroscopy. A maximum specific capacitance of 728.5 F g{sup −1} was achieved at a scan rate of 5 mV s{sup −1} for MnO{sub 2} electro-etched carbon fiber electrode. Also, this electrode showed exceptional cycle stability, suggesting that it can be considered as a good candidate for supercapacitor electrodes.« less

High resolution, wide field of view, real time 340GHz 3D imaging radar for security screening

NASA Astrophysics Data System (ADS)

Robertson, Duncan A.; Macfarlane, David G.; Hunter, Robert I.; Cassidy, Scott L.; Llombart, Nuria; Gandini, Erio; Bryllert, Tomas; Ferndahl, Mattias; Lindström, Hannu; Tenhunen, Jussi; Vasama, Hannu; Huopana, Jouni; Selkälä, Timo; Vuotikka, Antti-Jussi

2017-05-01

The EU FP7 project CONSORTIS (Concealed Object Stand-Off Real-Time Imaging for Security) is developing a demonstrator system for next generation airport security screening which will combine passive and active submillimeter wave imaging sensors. We report on the development of the 340 GHz 3D imaging radar which achieves high volumetric resolution over a wide field of view with high dynamic range and a high frame rate. A sparse array of 16 radar transceivers is coupled with high speed mechanical beam scanning to achieve a field of view of 1 x 1 x 1 m3 and a 10 Hz frame rate.

Characterization of rock thermal conductivity by high-resolution optical scanning

USGS Publications Warehouse

Popov, Y.A.; Pribnow, D.F.C.; Sass, J.H.; Williams, C.F.; Burkhardt, H.

1999-01-01

We compared thress laboratory methods for thermal conductivity measurements: divided-bar, line-source and optical scanning. These methods are widely used in geothermal and petrophysical studies, particularly as applied to research on cores from deep scientific boreholes. The relatively new optical scanning method has recently been perfected and applied to geophysical problems. A comparison among these methods for determining the thermal conductivity tensor for anisotropic rocks is based on a representative collection of 80 crystalline rock samples from the KTB continental deep borehole (Germany). Despite substantial thermal inhomogeneity of rock thermal conductivity (up to 40-50% variation) and high anisotropy (with ratios of principal values attaining 2 and more), the results of measurements agree very well among the different methods. The discrepancy for measurements along the foliation is negligible (<1%). The component of thermal conductivity normal to the foliation reveals somewhat larger differences (3-4%). Optical scanning allowed us to characterize the thermal inhomogeneity of rocks and to identify a three-dimensional anisotropy in thermal conductivity of some gneiss samples. The merits of optical scanning include minor random errors (1.6%), the ability to record the variation of thermal conductivity along the sample, the ability to sample deeply using a slow scanning rate, freedom from constraints for sample size and shape, and quality of mechanical treatment of the sample surface, a contactless mode of measurement, high speed of operation, and the ability to measure on a cylindrical sample surface. More traditional methods remain superior for characterizing bulk conductivity at elevated temperature.Three laboratory methods including divided-bar, line-source and optical scanning are widely applied in geothermal and petrophysical studies. In this study, these three methods were compared for determining the thermal conductivity tensor for anisotropic rocks. For this study, a representative collection of 80 crystalline rock samples from the KTB continental deep borehole was used. Despite substantial thermal inhomogeneity of rock thermal conductivity and high anisotropy, measurement results were in excellent agreement among the three methods.

Rapid-scan Fourier-transform coherent anti-Stokes Raman scattering spectroscopy with heterodyne detection.

PubMed

Hiramatsu, Kotaro; Luo, Yizhi; Ideguchi, Takuro; Goda, Keisuke

2017-11-01

High-speed Raman spectroscopy has become increasingly important for analyzing chemical dynamics in real time. To address the need, rapid-scan Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy has been developed to realize broadband CARS measurements at a scan rate of more than 20,000 scans/s. However, the detection sensitivity of FT-CARS spectroscopy is inherently low due to the limited number of photons detected during each scan. In this Letter, we show our experimental demonstration of enhanced sensitivity in rapid-scan FT-CARS spectroscopy by heterodyne detection. Specifically, we implemented heterodyne detection by superposing the CARS electric field with an external local oscillator (LO) for their interference. The CARS signal was amplified by simply increasing the power of the LO without the need for increasing the incident power onto the sample. Consequently, we achieved enhancement in signal intensity and the signal-to-noise ratio by factors of 39 and 5, respectively, compared to FT-CARS spectroscopy with homodyne detection. The sensitivity-improved rapid-scan FT-CARS spectroscopy is expected to enable the sensitive real-time observation of chemical dynamics in a broad range of settings, such as combustion engines and live biological cells.

Synchronous digitization for high dynamic range lock-in amplification in beam-scanning microscopy

PubMed Central

Muir, Ryan D.; Sullivan, Shane Z.; Oglesbee, Robert A.; Simpson, Garth J.

2014-01-01

Digital lock-in amplification (LIA) with synchronous digitization (SD) is shown to provide significant signal to noise (S/N) and linear dynamic range advantages in beam-scanning microscopy measurements using pulsed laser sources. Direct comparisons between SD-LIA and conventional LIA in homodyne second harmonic generation measurements resulted in S/N enhancements consistent with theoretical models. SD-LIA provided notably larger S/N enhancements in the limit of low light intensities, through the smooth transition between photon counting and signal averaging developed in previous work. Rapid beam scanning instrumentation with up to video rate acquisition speeds minimized photo-induced sample damage. The corresponding increased allowance for higher laser power without sample damage is advantageous for increasing the observed signal content. PMID:24689588

Multiphoton minimal inertia scanning for fast acquisition of neural activity signals

NASA Astrophysics Data System (ADS)

Schuck, Renaud; Go, Mary Ann; Garasto, Stefania; Reynolds, Stephanie; Dragotti, Pier Luigi; Schultz, Simon R.

2018-04-01

Objective. Multi-photon laser scanning microscopy provides a powerful tool for monitoring the spatiotemporal dynamics of neural circuit activity. It is, however, intrinsically a point scanning technique. Standard raster scanning enables imaging at subcellular resolution; however, acquisition rates are limited by the size of the field of view to be scanned. Recently developed scanning strategies such as travelling salesman scanning (TSS) have been developed to maximize cellular sampling rate by scanning only select regions in the field of view corresponding to locations of interest such as somata. However, such strategies are not optimized for the mechanical properties of galvanometric scanners. We thus aimed to develop a new scanning algorithm which produces minimal inertia trajectories, and compare its performance with existing scanning algorithms. Approach. We describe here the adaptive spiral scanning (SSA) algorithm, which fits a set of near-circular trajectories to the cellular distribution to avoid inertial drifts of galvanometer position. We compare its performance to raster scanning and TSS in terms of cellular sampling frequency and signal-to-noise ratio (SNR). Main Results. Using surrogate neuron spatial position data, we show that SSA acquisition rates are an order of magnitude higher than those for raster scanning and generally exceed those achieved by TSS for neural densities comparable with those found in the cortex. We show that this result also holds true for in vitro hippocampal mouse brain slices bath loaded with the synthetic calcium dye Cal-520 AM. The ability of TSS to ‘park’ the laser on each neuron along the scanning trajectory, however, enables higher SNR than SSA when all targets are precisely scanned. Raster scanning has the highest SNR but at a substantial cost in number of cells scanned. To understand the impact of sampling rate and SNR on functional calcium imaging, we used the Cramér-Rao Bound on evoked calcium traces recorded simultaneously with electrophysiology traces to calculate the lower bound estimate of the spike timing occurrence. Significance. The results show that TSS and SSA achieve comparable accuracy in spike time estimates compared to raster scanning, despite lower SNR. SSA is an easily implementable way for standard multi-photon laser scanning systems to gain temporal precision in the detection of action potentials while scanning hundreds of active cells.

Surface modification of ceramic and metallic alloy substrates by laser raster-scanning

NASA Astrophysics Data System (ADS)

Ramos Grez, Jorge Andres

This work describes the feasibility of continuous wave laser-raster scan-processing under controlled atmospheric conditions as employed in three distinct surface modification processes: (a) surface roughness reduction of indirect-Selective Laser Sintered 420 martensitic stainless steel-40 wt. % bronze infiltrated surfaces; (b) Si-Cr-Hf-C coating consolidation over 3D carbon-carbon composites cylinders; (c) dendritic solidification structures of Mar-M 247 confined powder precursor grown from polycrystalline Alloy 718 substrates. A heat transfer model was developed to illustrate that the aspect ratio of the laser scanned pattern and the density of scanning lines play a significant role in determining peak surface temperature, heating and cooling rates and melt resident times. Comprehensive characterization of the surface of the processed specimens was performed using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), optical metallography, X-ray diffraction (XRD), and, in certain cases, tactile profilometry. In Process (a), it was observed that a 24% to 37% roughness Ra reduction could be accomplished from the as-received value of 2.50+/-0.10 microns for laser energy densities ranging from 350 to 500 J/cm2. In Process (b), complete reactive wetting of carbon-carbon composite cylinders surface was achieved by laser melting a Si-Cr-Hf-C slurry. Coatings showed good thermal stability at 1000°C in argon, and, when tested in air, a percent weight reduction rate of -6.5 wt.%/hr was achieved. A soda-glass overcoat applied over the coated specimens by conventional means revealed a percent weight reduction rate between -1.4 to -2.2 wt.%/hr. Finally, in Process (c), microstructure of the Mar-M 247 single layer deposits, 1 mm in height, grown on Alloy 718 polycrystalline sheets, resulted in a sound metallurgical bond, low porosity, and uniform thickness. Polycrystalline dendrites grew preferentially along the [001] direction from the substrate up to 400 microns. Above that height, dendrites appear to shift towards the [100] growth direction driven by the thermal gradient and solidification front velocity. This research demonstrated that surface modification by high speed raster-scanning a high power laser beam under controlled atmospheric conditions is a feasible and versatile technique that can accomplish diverse purposes involving metallic as well as ceramic surfaces.

Quantification of pilot workload via instrument scan

NASA Technical Reports Server (NTRS)

Tole, J. R.; Stephens, A. T.; Harris, R. L., Sr.; Ephrath, A.

1982-01-01

The use of visual scanning behavior as an indicator of pilot workload is described. The relationship between level of performance on a constant piloting task under simulated IFR conditions, the skill of the pilot the level of mental workload induced by an additional verbal task imposed on the basic control task, and visual scanning behavior is investigated. An increase in fixation dwell times, especially on the primary instrument with increased mental loading is indicated. Skilled subjects 'stared' less under increased loading than did novice pilots. Sequences of instrument fixations were also examined. The percentage occurrence of the subject's most used sequences decreased with increased task difficulty for novice subjects but not for highly skilled subjects. Entropy rate (bits/sec) of the sequence of fixations was also used to quantify the scan pattern. It consistently decreased for most subjects as the four loading levels used increased.

Continuous wave dye-laser technique for simultaneous, spatially resolved measurements of temperature, pressure, and velocity of NO in an underexpanded free jet

NASA Technical Reports Server (NTRS)

Di Rosa, Michael D.; Chang, Albert Y.; Hanson, Ronald K.

1993-01-01

Gas dynamic quantities within an underexpanded nitrogen free jet, seeded with 0.5 percent NO, were measured nonintrusively by using an intracavity-doubled, rapid-tuning, CW ring dye laser. The UV beam passed obliquely through the jet axis, and its frequency repetitively scanned across adjacent rotational lines in the NO gamma band near 225 nm at a rate of 4 kHz. Spatially resolved excitation scans were obtained by monitoring the induced broadband fluoresence. Modeling the Doppler-shifted excitation scans with Voigt profiles permitted simultaneous determinations of NO velocity, rotational temperature, and pressure. Zero Doppler shift was referenced to an absorption trace obtained across a static cell and recorded concurrently with the excitation scan. Typically, the measured and predicted axial distributions agreed within 10 percent. At high Mach numbers there was evidence of rotational freezing of NO.

Tri-linear color multi-linescan sensor with 200 kHz line rate

NASA Astrophysics Data System (ADS)

Schrey, Olaf; Brockherde, Werner; Nitta, Christian; Bechen, Benjamin; Bodenstorfer, Ernst; Brodersen, Jörg; Mayer, Konrad J.

2016-11-01

In this paper we present a newly developed linear CMOS high-speed line-scanning sensor realized in a 0.35 μm CMOS OPTO process for line-scan with 200 kHz true RGB and 600 kHz monochrome line rate, respectively. In total, 60 lines are integrated in the sensor allowing for electronic position adjustment. The lines are read out in rolling shutter manner. The high readout speed is achieved by a column-wise organization of the readout chain. At full speed, the sensor provides RGB color images with a spatial resolution down to 50 μm. This feature enables a variety of applications like quality assurance in print inspection, real-time surveillance of railroad tracks, in-line monitoring in flat panel fabrication lines and many more. The sensor has a fill-factor close to 100%, preventing aliasing and color artefacts. Hence the tri-linear technology is robust against aliasing ensuring better inspection quality and thus less waste in production lines.

Laser Cladding of TiAl Intermetallic Alloy on Ti6Al4V -Process Optimization and Properties

NASA Astrophysics Data System (ADS)

Cárcel, B.; Serrano, A.; Zambrano, J.; Amigó, V.; Cárcel, A. C.

In order to improve Ti6Al4V high-temperature resistance and its tribological properties, the deposition of TiAl intermetallic (Ti-48Al-2Cr-2Nb) coating on a Ti6Al4V substrate by coaxial laser cladding has been investigated. Laser cladding by powder injection is an emerging laser material processing technique that allows the deposition of thick protective coatings on substrates,using a high power laser beam as heat source. Laser cladding is a multiple-parameter-dependent process. The main process parameters involved (laser power, powder feeding rate, scanning speed and preheating temperature) has been optimized. The microstructure and geometrical quantities (clad area and dilution) of the coating was characterized by optical microscopy and scanning electron microscopy (SEM). In addition the cooling rate of the clad during the process was measured by a dual-color pyrometer. This result has been related to defectology and mechanical coating properties.

Self-assembled growth of MnSi~1.7 nanowires with a single orientation and a large aspect ratio on Si(110) surfaces

PubMed Central

2013-01-01

MnSi~1.7 nanowires (NWs) with a single orientation and a large aspect ratio have been formed on a Si(110) surface with the molecular beam epitaxy method by a delicate control of growth parameters, such as temperature, deposition rate, and deposition time. Scanning tunneling microscopy (STM) was employed to study the influence of these parameters on the growth of NWs. The supply of free Si atoms per unit time during the silicide reaction plays a critical role in the growth kinetics of the NWs. High growth temperature and low deposition rate are favorable for the formation of NWs with a large aspect ratio. The orientation relationship between the NWs and the reconstruction rows of the Si(110) surface suggests that the NWs grow along the 11¯0 direction of the silicon substrate. High-resolution STM and backscattered electron scanning electron microscopy images indicate that the NWs are composed of MnSi~1.7. PMID:23339353

Electronically scanned pressure sensor module with in SITU calibration capability

NASA Technical Reports Server (NTRS)

Gross, C. (Inventor)

1978-01-01

This high data rate pressure sensor module helps reduce energy consumption in wind tunnel facilities without loss of measurement accuracy. The sensor module allows for nearly a two order of magnitude increase in data rates over conventional electromechanically scanned pressure sampling techniques. The module consists of 16 solid state pressure sensor chips and signal multiplexing electronics integrally mounted to a four position pressure selector switch. One of the four positions of the pressure selector switch allows the in situ calibration of the 16 pressure sensors; the three other positions allow 48 channels (three sets of 16) pressure inputs to be measured by the sensors. The small size of the sensor module will allow mounting within many wind tunnel models, thus eliminating long tube lengths and their corresponding slow pressure response.

Implementation of HPV vaccination guidelines in a diverse population in Los Angeles: Results from an environmental scan of local HPV resources and needs.

PubMed

Baezconde-Garbanati, Lourdes; Lienemann, Brianna A; Robles, Marisela; Johnson, Ethel; Sanchez, Kathleen; Singhal, Rita; Steinberg, Jane; Jaque, Jenny M; Pentz, Mary Ann; Gruber, Stephen

2017-09-05

Research shows that vaccination against human papillomavirus (HPV) infection is one of the most effective methods for reducing risk for cervical cancer; it also protects against other HPV-related cancers. Controversies exist regarding HPV vaccination in several communities; which may in part explain why although rates of HPV vaccination are increasing nationwide, Los Angeles County (LAC) data show that many adolescents are still not vaccinated. These adolescents remain at high-risk for infection. Using community-based participatory principles, we conducted an environmental scan that included a literature review, the development of a community advisory board, community feedback from HPV community meetings, and interviews with stakeholders to understand attitudes toward HPV vaccination and their impact in follow through with HPV vaccines. Twenty-eight key stakeholders participated in our coalition comprised of community organizations and clinics with strong ties to the local community. This is the only coalition dedicated exclusively to improving HPV vaccine uptake in LAC. Of these, twenty-one participated in an environmental scan via qualitative interviews about HPV vaccination programs, service delivery priorities, and proposed steps to increase HPV vaccination uptake in LAC. The environmental scan revealed targets for future efforts, barriers to HPV uptake, and next steps for improving local HPV vaccination uptake rates. The environmental scan also identified local HPV vaccination interventions and resources. Although LAC has developed important efforts for vaccination, some interventions are no longer being implemented due to lack of funds; others have not been evaluated with sufficient outcome data. The risk for cervical and other HPV-related cancers could be greatly reduced in LAC if a multilevel, multicultural, and multilingual approach is taken to better understand rates of HPV vaccination uptake, particularly among racial/ethnic minorities and LGBTQ youth. Our environmental scan provides guidance on attitudes toward vaccination, and how best to address the needs of LAC families and providers. Copyright © 2017 Elsevier Ltd. All rights reserved.

High-Rate Charging Induced Intermediate Phases and Structural Changes of Layer-Structured Cathode for Lithium-Ion Batteries

DOE PAGES

Zhou, Yong-Ning; Yue, Ji-Li; Hu, Enyuan; ...

2016-08-08

Using fast time-resolved in situ X-ray diffraction, charge-rate dependent phase transition processes of layer structured cathode material LiNi 1/3Mn 1/3Co 1/3O 2 for lithium-ion batteries are studied. During first charge, intermediate phases emerge at high rates of 10C, 30C, and 60C, but not at low rates of 0.1C and 1C. These intermediate phases can be continuously observed during relaxation after the charging current is switched off. After half-way charging at high rate, sample studied by scanning transmission electron microscopy shows Li-rich and Li-poor phases' coexistence with tetrahedral occupation of Li in Li-poor phase. Also, the high rate induced overpotential ismore » thought to be the driving force for the formation of this intermediate Li-poor phase. The in situ quick X-ray absorption results show that the oxidation of Ni accelerates with increasing charging rate and the Ni 4+ state can be reached at the end of charge with 30C rate. Finally, these results give new insights in the understanding of the layered cathodes during high-rate charging.« less

A novel system to diagnose cutaneous adverse drug reactions employing the cellscan--comparison with histamine releasing test and Inf-gamma Releasing Test.

PubMed

Goldberg, Ilan; Gilburd, Boris; Kravitz, Martine Szyper; Kivity, Shmuel; Chaim, Berta Ben; Klein, Tirza; Schiffenbauer, Yael; Trubniykovr, Ela; Brenner, Sarah; Shoenfeld, Yehuda

2005-03-01

There are several mechanisms to describe allergic drug reactions yet the methods to diagnose them are limited. To compare several conventional clinical and laboratory methods to diagnose skin reactions to drugs to a new method of diagnosing drug reactions by the CellScan system. The study entailed 21 patients who were diagnosed as suffering from drug eruptions, and 105 healthy controls with no history of drug allergy. The drugs were classified into two groups according to suspicion of causing drug allergy: high and low. Most of the patients were on more than one drug, leading to 41 patient-drug interactions (assays). Histamine releasing test (HRT), interferon (INF)-gamma releasing test and CellScan examination were performed on lymphocytes of the patients and controls. The HRTwas interpreted as positive in 9 out of 18 (50%) patients and in 13 out of 35 (37%) assays. Based on the INF-gamma releasing test, positive results were observed in 16 out of 21 (76%) patients and in 24 out of 41 (59%) assays. In the CellScan test (CST), positive results were observed in 17 out of 21 (81%) patients and in 29 out of 41 (71%) assays. The rate of identifying the drug for eruption in the high suspicion level drugs was 9 out of 22 (41%) assays in the HRT, 20 out of 24 (83%) assays in the INF-gamma releasing test, and 21 out of 24 (87%) studies with the CellScan method. The rate of determining of the drug that caused the eruption in the low suspicion level drugs was 4 out of 13 (31 %) in the HRT, 4 out of 17 (24%) assays in the INF-gamma releasing test, and 8 out of 17 (47%) analyses in the CST. When examined in the CellScan, 99 out of 105 (94%) controls were interpreted as negative. This preliminary study indicates that the CellScan seems to be an easy and promising method for the detection of drugs responsible for adverse skin reactions. In contrast to the HRT and to the Interferon-gamma secretion test, the CellScan method is characterized by its ability to track and monitor the reaction of individual cells. By measuring the kinetic parameters of selected cells before and after adding the suspected drug, we were able to identify the culprit drug. The CellScan method had the highest sensitivity, and the interferon-gamma secretion test had the highest specificity for detection of the culprit drug. In contrast, the analysis of 105 normal control sera disclosed a high specificity of 94% for the CellScan method.

Line scanning system for direct digital chemiluminescence imaging of DNA sequencing blots

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

Karger, A.E.; Weiss, R.; Gesteland, R.F.

A cryogenically cooled charge-coupled device (CCD) camera equipped with an area CCD array is used in a line scanning system for low-light-level imaging of chemiluminescent DNA sequencing blots. Operating the CCD camera in time-delayed integration (TDI) mode results in continuous data acquisition independent of the length of the CCD array. Scanning is possible with a resolution of 1.4 line pairs/mm at the 50% level of the modulation transfer function. High-sensitivity, low-light-level scanning of chemiluminescent direct-transfer electrophoresis (DTE) DNA sequencing blots is shown. The detection of DNA fragments on the blot involves DNA-DNA hybridization with oligonucleotide-alkaline phosphatase conjugate and 1,2-dioxetane-based chemiluminescence.more » The width of the scan allows the recording of up to four sequencing reactions (16 lanes) on one scan. The scan speed of 52 cm/h used for the sequencing blots corresponds to a data acquisition rate of 384 pixels/s. The chemiluminescence detection limit on the scanned images is 3.9 [times] 10[sup [minus]18] mol of plasmid DNA. A conditional median filter is described to remove spikes caused by cosmic ray events from the CCD images. 39 refs., 9 refs.« less

Backside illuminated CMOS-TDI line scan sensor for space applications

NASA Astrophysics Data System (ADS)

Cohen, Omer; Ofer, Oren; Abramovich, Gil; Ben-Ari, Nimrod; Gershon, Gal; Brumer, Maya; Shay, Adi; Shamay, Yaron

2018-05-01

A multi-spectral backside illuminated Time Delayed Integration Radiation Hardened line scan sensor utilizing CMOS technology was designed for continuous scanning Low Earth Orbit small satellite applications. The sensor comprises a single silicon chip with 4 independent arrays of pixels where each array is arranged in 2600 columns with 64 TDI levels. A multispectral optical filter whose spectral responses per array are adjustable per system requirement is assembled at the package level. A custom 4T Pixel design provides the required readout speed, low-noise, very low dark current, and high conversion gains. A 2-phase internally controlled exposure mechanism improves the sensor's dynamic MTF. The sensor high level of integration includes on-chip 12 bit per pixel analog to digital converters, on-chip controller, and CMOS compatible voltage levels. Thus, the power consumption and the weight of the supporting electronics are reduced, and a simple electrical interface is provided. An adjustable gain provides a Full Well Capacity ranging from 150,000 electrons up to 500,000 electrons per column and an overall readout noise per column of less than 120 electrons. The imager supports line rates ranging from 50 to 10,000 lines/sec, with power consumption of less than 0.5W per array. Thus, the sensor is characterized by a high pixel rate, a high dynamic range and a very low power. To meet a Latch-up free requirement RadHard architecture and design rules were utilized. In this paper recent electrical and electro-optical measurements of the sensor's Flight Models will be presented for the first time.

Feasibility and radiation dose of high-pitch acquisition protocols in patients undergoing dual-source cardiac CT.

PubMed

Sommer, Wieland H; Albrecht, Edda; Bamberg, Fabian; Schenzle, Jan C; Johnson, Thorsten R; Neumaier, Klement; Reiser, Maximilian F; Nikolaou, Konstatin

2010-12-01

The objective of this study was to compare image quality and radiation dose between high-pitch and established retrospectively and prospectively gated cardiac CT protocols using an Alderson-Rando phantom and a set of patients. An anthropomorphic Alderson-Rando phantom equipped with thermoluminiscent detectors and a set of clinical patients underwent the following cardiac CT protocols: high-pitch acquisition (pitch 3.4), prospectively triggered acquisition, and retrospectively gated acquisition (pitch 0.2). For patients with sinus rhythm below 65 beats per minute (bpm), high-pitch protocol was used, whereas for patients in sinus rhythm between 65 and 100 bpm, prospective triggering was used. Patients with irregular heart rates or heart rates of ≥ 100 bpm, were examined using retrospectively gated acquisition. Evaluability of coronary artery segments was determined, and effective radiation dose was derived from the phantom study. In the phantom study, the effective radiation dose as determined with thermoluminescent detector (TLD) measurements was lowest in the high-pitch acquisition (1.21, 3.12, and 11.81 mSv, for the high-pitch, the prospectively triggered, and the retrospectively gated acquisition, respectively). There was a significant difference with respect to the percentage of motion-free coronary artery segments (99%, 87%, and 92% for high-pitch, prospectively triggered, and retrospectively gated, respectively (p < 0.001), whereas image noise was lowest for the high-pitch protocol (p < 0.05). High-pitch scans have the potential to reduce radiation dose up to 61.2% and 89.8% compared with prospectively triggered and retrospectively gated scans. High-pitch protocols lead to excellent image quality when used in patients with stable heart rates below 65 bpm.

From nanoparticles to large aerosols: Ultrafast measurement methods for size and concentration

NASA Astrophysics Data System (ADS)

Keck, Lothar; Spielvogel, Jürgen; Grimm, Hans

2009-05-01

A major challenge in aerosol technology is the fast measurement of number size distributions with good accuracy and size resolution. The dedicated instruments are frequently based on particle charging and electric detection. Established fast systems, however, still feature a number of shortcomings. We have developed a new instrument that constitutes of a high flow Differential Mobility Analyser (high flow DMA) and a high sensitivity Faraday Cup Electrometer (FCE). The system enables variable flow rates of up to 150 lpm, and the scan time for size distribution can be shortened considerably due to the short residence time of the particles in the DMA. Three different electrodes can be employed in order to cover a large size range. First test results demonstrate that the scan time can be reduced to less than 1 s for small particles, and that the results from the fast scans feature no significant difference to the results from established slow method. The fields of application for the new instrument comprise the precise monitoring of fast processes with nanoparticles, including monitoring of engine exhaust in automotive research.

A Fully-Automated Subcortical and Ventricular Shape Generation Pipeline Preserving Smoothness and Anatomical Topology

PubMed Central

Tang, Xiaoying; Luo, Yuan; Chen, Zhibin; Huang, Nianwei; Johnson, Hans J.; Paulsen, Jane S.; Miller, Michael I.

2018-01-01

In this paper, we present a fully-automated subcortical and ventricular shape generation pipeline that acts on structural magnetic resonance images (MRIs) of the human brain. Principally, the proposed pipeline consists of three steps: (1) automated structure segmentation using the diffeomorphic multi-atlas likelihood-fusion algorithm; (2) study-specific shape template creation based on the Delaunay triangulation; (3) deformation-based shape filtering using the large deformation diffeomorphic metric mapping for surfaces. The proposed pipeline is shown to provide high accuracy, sufficient smoothness, and accurate anatomical topology. Two datasets focused upon Huntington's disease (HD) were used for evaluating the performance of the proposed pipeline. The first of these contains a total of 16 MRI scans, each with a gold standard available, on which the proposed pipeline's outputs were observed to be highly accurate and smooth when compared with the gold standard. Visual examinations and outlier analyses on the second dataset, which contains a total of 1,445 MRI scans, revealed 100% success rates for the putamen, the thalamus, the globus pallidus, the amygdala, and the lateral ventricle in both hemispheres and rates no smaller than 97% for the bilateral hippocampus and caudate. Another independent dataset, consisting of 15 atlas images and 20 testing images, was also used to quantitatively evaluate the proposed pipeline, with high accuracy having been obtained. In short, the proposed pipeline is herein demonstrated to be effective, both quantitatively and qualitatively, using a large collection of MRI scans. PMID:29867332

A Fully-Automated Subcortical and Ventricular Shape Generation Pipeline Preserving Smoothness and Anatomical Topology.

PubMed

Tang, Xiaoying; Luo, Yuan; Chen, Zhibin; Huang, Nianwei; Johnson, Hans J; Paulsen, Jane S; Miller, Michael I

2018-01-01

In this paper, we present a fully-automated subcortical and ventricular shape generation pipeline that acts on structural magnetic resonance images (MRIs) of the human brain. Principally, the proposed pipeline consists of three steps: (1) automated structure segmentation using the diffeomorphic multi-atlas likelihood-fusion algorithm; (2) study-specific shape template creation based on the Delaunay triangulation; (3) deformation-based shape filtering using the large deformation diffeomorphic metric mapping for surfaces. The proposed pipeline is shown to provide high accuracy, sufficient smoothness, and accurate anatomical topology. Two datasets focused upon Huntington's disease (HD) were used for evaluating the performance of the proposed pipeline. The first of these contains a total of 16 MRI scans, each with a gold standard available, on which the proposed pipeline's outputs were observed to be highly accurate and smooth when compared with the gold standard. Visual examinations and outlier analyses on the second dataset, which contains a total of 1,445 MRI scans, revealed 100% success rates for the putamen, the thalamus, the globus pallidus, the amygdala, and the lateral ventricle in both hemispheres and rates no smaller than 97% for the bilateral hippocampus and caudate. Another independent dataset, consisting of 15 atlas images and 20 testing images, was also used to quantitatively evaluate the proposed pipeline, with high accuracy having been obtained. In short, the proposed pipeline is herein demonstrated to be effective, both quantitatively and qualitatively, using a large collection of MRI scans.

Passive 350 GHz Video Imaging Systems for Security Applications

NASA Astrophysics Data System (ADS)

Heinz, E.; May, T.; Born, D.; Zieger, G.; Anders, S.; Zakosarenko, V.; Meyer, H.-G.; Schäffel, C.

2015-10-01

Passive submillimeter-wave imaging is a concept that has been in the focus of interest as a promising technology for personal security screening for a number of years. In contradiction to established portal-based millimeter-wave scanning techniques, it allows for scanning people from a distance in real time with high throughput and without a distinct inspection procedure. This opens up new possibilities for scanning, which directly address an urgent security need of modern societies: protecting crowds and critical infrastructure from the growing threat of individual terror attacks. Considering the low radiometric contrast of indoor scenes in the submillimeter range, this objective calls for an extremely high detector sensitivity that can only be achieved using cooled detectors. Our approach to this task is a series of passive standoff video cameras for the 350 GHz band that represent an evolving concept and a continuous development since 2007. Arrays of superconducting transition-edge sensors (TES), operated at temperatures below 1 K, are used as radiation detectors. By this means, background limited performance (BLIP) mode is achieved, providing the maximum possible signal to noise ratio. At video rates, this leads to a temperature resolution well below 1 K. The imaging system is completed by reflector optics based on free-form mirrors. For object distances of 5-25 m, a field of view up to 2 m height and a diffraction-limited spatial resolution in the order of 1-2 cm is provided. Opto-mechanical scanning systems are part of the optical setup and capable of frame rates of up to 25 frames per second.

Relationship between heart rate and quiescent interval of the cardiac cycle in children using MRI.

PubMed

Zhang, Wei; Bogale, Saivivek; Golriz, Farahnaz; Krishnamurthy, Rajesh

2017-11-01

Imaging the heart in children comes with the challenge of constant cardiac motion. A prospective electrocardiography-triggered CT scan allows for scanning during a predetermined phase of the cardiac cycle with least motion. This technique requires knowing the optimal quiescent intervals of cardiac cycles in a pediatric population. To evaluate high-temporal-resolution cine MRI of the heart in children to determine the relationship of heart rate to the optimal quiescent interval within the cardiac cycle. We included a total of 225 consecutive patients ages 0-18 years who had high-temporal-resolution cine steady-state free-precession sequence performed as part of a magnetic resonance imaging (MRI) or magnetic resonance angiography study of the heart. We determined the location and duration of the quiescent interval in systole and diastole for heart rates ranging 40-178 beats per minute (bpm). We performed the Wilcoxon signed rank test to compare the duration of quiescent interval in systole and diastole for each heart rate group. The duration of the quiescent interval at heart rates <80 bpm and >90 bpm was significantly longer in diastole and systole, respectively (P<.0001 for all ranges, except for 90-99 bpm [P=.02]). For heart rates 80-89 bpm, diastolic interval was longer than systolic interval, but the difference was not statistically significant (P=.06). We created a chart depicting optimal quiescent intervals across a range of heart rates that could be applied for prospective electrocardiography-triggered CT imaging of the heart. The optimal quiescent interval at heart rates <80 bpm is in diastole and at heart rates ≥90 bpm is in systole. The period of quiescence at heart rates 80-89 bpm is uniformly short in systole and diastole.

Wide-Field Megahertz OCT Imaging of Patients with Diabetic Retinopathy

PubMed Central

Reznicek, Lukas; Kolb, Jan P.; Klein, Thomas; Mohler, Kathrin J.; Huber, Robert; Kernt, Marcus; Märtz, Josef; Neubauer, Aljoscha S.

2015-01-01

Purpose. To evaluate the feasibility of wide-field Megahertz (MHz) OCT imaging in patients with diabetic retinopathy. Methods. A consecutive series of 15 eyes of 15 patients with diagnosed diabetic retinopathy were included. All patients underwent Megahertz OCT imaging, a close clinical examination, slit lamp biomicroscopy, and funduscopic evaluation. To acquire densely sampled, wide-field volumetric datasets, an ophthalmic 1050 nm OCT prototype system based on a Fourier-domain mode-locked (FDML) laser source with 1.68 MHz A-scan rate was employed. Results. We were able to obtain OCT volume scans from all included 15 patients. Acquisition time was 1.8 seconds. Obtained volume datasets consisted of 2088 × 1044 A-scans of 60° of view. Thus, reconstructed en face images had a resolution of 34.8 pixels per degree in x-axis and 17.4 pixels per degree. Due to the densely sampled OCT volume dataset, postprocessed customized cross-sectional B-frames through pathologic changes such as an individual microaneurysm or a retinal neovascularization could be imaged. Conclusions. Wide-field Megahertz OCT is feasible to successfully image patients with diabetic retinopathy at high scanning rates and a wide angle of view, providing information in all three axes. The Megahertz OCT is a useful tool to screen diabetic patients for diabetic retinopathy. PMID:26273665

Wide-Field Megahertz OCT Imaging of Patients with Diabetic Retinopathy.

PubMed

Reznicek, Lukas; Kolb, Jan P; Klein, Thomas; Mohler, Kathrin J; Wieser, Wolfgang; Huber, Robert; Kernt, Marcus; Märtz, Josef; Neubauer, Aljoscha S

2015-01-01

To evaluate the feasibility of wide-field Megahertz (MHz) OCT imaging in patients with diabetic retinopathy. A consecutive series of 15 eyes of 15 patients with diagnosed diabetic retinopathy were included. All patients underwent Megahertz OCT imaging, a close clinical examination, slit lamp biomicroscopy, and funduscopic evaluation. To acquire densely sampled, wide-field volumetric datasets, an ophthalmic 1050 nm OCT prototype system based on a Fourier-domain mode-locked (FDML) laser source with 1.68 MHz A-scan rate was employed. RESULTS. We were able to obtain OCT volume scans from all included 15 patients. Acquisition time was 1.8 seconds. Obtained volume datasets consisted of 2088 × 1044 A-scans of 60° of view. Thus, reconstructed en face images had a resolution of 34.8 pixels per degree in x-axis and 17.4 pixels per degree. Due to the densely sampled OCT volume dataset, postprocessed customized cross-sectional B-frames through pathologic changes such as an individual microaneurysm or a retinal neovascularization could be imaged. Wide-field Megahertz OCT is feasible to successfully image patients with diabetic retinopathy at high scanning rates and a wide angle of view, providing information in all three axes. The Megahertz OCT is a useful tool to screen diabetic patients for diabetic retinopathy.

Aerosol-assisted chemical vapor deposition of V2O5 cathodes with high rate capabilities for magnesium-ion batteries

NASA Astrophysics Data System (ADS)

Drosos, Charalampos; Jia, Chenglin; Mathew, Shiny; Palgrave, Robert G.; Moss, Benjamin; Kafizas, Andreas; Vernardou, Dimitra

2018-04-01

The growth of orthorhombic vanadium pentoxide nanostructures was accomplished using an aerosol-assisted chemical vapor deposition process. These materials showed excellent electrochemical performance for magnesium-ion storage in an aqueous electrolyte; showing specific discharge capacities of up to 427 mAh g-1 with a capacity retention of 82% after 2000 scans under a high specific current of 5.9 A g-1. The high rate capability suggested good structural stability and high reversibility. We believe the development of low-cost and large-area coating methods, such as the technique used herein, will be essential for the upscalable fabrication of next-generation rechargeable battery technologies.

Ultrashort pulsed laser (USPL) application in dentistry: basic investigations of ablation rates and thresholds on oral hard tissue and restorative materials.

PubMed

Schelle, Florian; Polz, Sebastian; Haloui, Hatim; Braun, Andreas; Dehn, Claudia; Frentzen, Matthias; Meister, Jörg

2014-11-01

Modern ultrashort pulse lasers with scanning systems provide a huge set of parameters affecting the suitability for dental applications. The present study investigates thresholds and ablation rates of oral hard tissues and restorative materials with a view towards a clinical application system. The functional system consists of a 10 W Nd:YVO4 laser emitting pulses with a duration of 8 ps at 1,064 nm. Measurements were performed on dentin, enamel, ceramic, composite, and mammoth ivory at a repetition rate of 500 kHz. By employing a scanning system, square-shaped cavities with an edge length of 1 mm were created. Ablation threshold and rate measurements were assessed by variation of the applied fluence. Examinations were carried out employing a scanning electron microscope and optical profilometer. Irradiation time was recorded by the scanner software in order to calculate the overall ablated volume per time. First high power ablation rate measurements were performed employing a laser source with up to 50 W. Threshold values in the range of 0.45 J/cm(2) (composite) to 1.54 J/cm(2) (enamel) were observed. Differences between any two materials are statistically significant (p < 0.05). Preparation speeds up to 37.53 mm(3)/min (composite) were achieved with the 10 W laser source and differed statistically significant for any two materials (p < 0.05) with the exception of dentin and mammoth ivory (p > 0.05). By employing the 50 W laser source, increased rates up to ∼50 mm(3)/min for dentin were obtained. The results indicate that modern USPL systems provide sufficient ablation rates to be seen as a promising technology for dental applications.

A p-nitroaniline redox-active solid-state electrolyte for battery-like electrochemical capacitive energy storage combined with an asymmetric supercapacitor based on metal oxide functionalized β-polytype porous silicon carbide electrodes.

PubMed

Kim, Myeongjin; Yoo, Jeeyoung; Kim, Jooheon

2017-05-23

A unique redox active flexible solid-state asymmetric supercapacitor with ultra-high capacitance and energy density was fabricated using a composite comprising MgCo 2 O 4 nanoneedles and micro and mesoporous silicon carbide flakes (SiCF) (SiCF/MgCo 2 O 4 ) as the positive electrode material. Due to the synergistic effect of the two materials, this hybrid electrode has a high specific capacitance of 516.7 F g -1 at a scan rate of 5 mV s -1 in a 1 M KOH aqueous electrolyte. To obtain a reasonable matching of positive and negative electrode pairs, a composite of Fe 3 O 4 nanoparticles and SiCF (SiCF/Fe 3 O 4 ) was synthesized for use as a negative electrode material, which shows a high capacitance of 423.2 F g -1 at a scan rate of 5 mV s -1 . Therefore, by pairing the SiCF/MgCo 2 O 4 positive electrode and the SiCF/Fe 3 O 4 negative electrode with a redox active quasi-solid-state PVA-KOH-p-nitroaniline (PVA-KOH-PNA) gel electrolyte, a novel solid-state asymmetric supercapacitor device was assembled. Because of the synergistic effect between the highly porous SiCF and the vigorous redox-reaction of metal oxides, the hybrid nanostructure electrodes exhibited outstanding charge storage and transport. In addition, the redox active PVA-KOH-PNA electrolyte adds additional pseudocapacitance, which arises from the nitro-reduction and oxidation and reduction process of the reduction product of p-phenylenediamine, resulting in an enhancement of the capacitance (a specific capacitance of 161.77 F g -1 at a scan rate of 5 mV s -1 ) and energy density (maximum energy density of 72.79 Wh kg -1 at a power density of 727.96 W kg -1 ).

High capacity aerodynamic air bearing (HCAB) for laser scanning applications

NASA Astrophysics Data System (ADS)

Coleman, Sean M.

2005-08-01

A high capacity aerodynamic air bearing (HCAB) has been developed for the laser scanning market. The need for increasing accuracies in the prepress and print plate-making market is causing a shift from ball bearing to air bearing scanners. Aerostatic air bearings are a good option to meet this demand for better performance however, these bearings tend to be expensive and require an additional air supply, filtering and drying system. Commercially available aerodynamic bearings have been typically limited to small mirrors, on the order of 3.5" diameter and less than 0.5" thick. A large optical facet, hence a larger mirror, is required to generate the high number of pixels needed for this type of application. The larger optic necessitated the development of a high capacity 'self-generating' or aerodynamic air bearing that would meet the needs of the optical scanning market. Its capacity is rated up to 6.0" diameter and 1.0" thick optics. The performance of an aerodynamic air bearing is better than a ball bearing and similar to an aerostatic air bearing. It retains the low costs while eliminating the need for ancillary equipment required by an aerostatic bearing.

Huffman and linear scanning methods with statistical language models.

PubMed

Roark, Brian; Fried-Oken, Melanie; Gibbons, Chris

2015-03-01

Current scanning access methods for text generation in AAC devices are limited to relatively few options, most notably row/column variations within a matrix. We present Huffman scanning, a new method for applying statistical language models to binary-switch, static-grid typing AAC interfaces, and compare it to other scanning options under a variety of conditions. We present results for 16 adults without disabilities and one 36-year-old man with locked-in syndrome who presents with complex communication needs and uses AAC scanning devices for writing. Huffman scanning with a statistical language model yielded significant typing speedups for the 16 participants without disabilities versus any of the other methods tested, including two row/column scanning methods. A similar pattern of results was found with the individual with locked-in syndrome. Interestingly, faster typing speeds were obtained with Huffman scanning using a more leisurely scan rate than relatively fast individually calibrated scan rates. Overall, the results reported here demonstrate great promise for the usability of Huffman scanning as a faster alternative to row/column scanning.

Spectral domain optical coherence tomography of multi-MHz A-scan rates at 1310 nm range and real-time 4D-display up to 41 volumes/second

PubMed Central

Choi, Dong-hak; Hiro-Oka, Hideaki; Shimizu, Kimiya; Ohbayashi, Kohji

2012-01-01

An ultrafast frequency domain optical coherence tomography system was developed at A-scan rates between 2.5 and 10 MHz, a B-scan rate of 4 or 8 kHz, and volume-rates between 12 and 41 volumes/second. In the case of the worst duty ratio of 10%, the averaged A-scan rate was 1 MHz. Two optical demultiplexers at a center wavelength of 1310 nm were used for linear-k spectral dispersion and simultaneous differential signal detection at 320 wavelengths. The depth-range, sensitivity, sensitivity roll-off by 6 dB, and axial resolution were 4 mm, 97 dB, 6 mm, and 23 μm, respectively. Using FPGAs for FFT and a GPU for volume rendering, a real-time 4D display was demonstrated at a rate up to 41 volumes/second for an image size of 256 (axial) × 128 × 128 (lateral) voxels. PMID:23243560

Effect of emergency department CT on neuroimaging case volume and positive scan rates.

PubMed

Oguz, Kader Karli; Yousem, David M; Deluca, Tom; Herskovits, Edward H; Beauchamp, Norman J

2002-09-01

The authors performed this study to determine the effect a computed tomographic (CT) scanner in the emergency department (ED) has on neuroimaging case volume and positive scan rates. The total numbers of ED visits and neuroradiology CT scans requested from the ED were recorded for 1998 and 2000, the years before and after the installation of a CT unit in the ED. For each examination type (brain, face, cervical spine), studies were graded for major findings (those that affected patient care), minor findings, and normal findings. The CT utilization rates and positive study rates were compared for each type of study performed for both years. There was a statistically significant increase in the utilization rate after installation of the CT unit (P < .001). The fractions of studies with major findings, minor findings, and normal findings changed significantly after installation of the CT unit for facial examinations (P = .002) but not for brain (P = .12) or cervical spine (P = .24) examinations. In all types of studies, the percentage of normal examinations increased. In toto, there was a significant decrease in the positive scan rate after installation of the CT scanner (P = .004). After installation of a CT scanner in the ED, there was increased utilization and a decreased rate of positive neuroradiologic examinations, the latter primarily due to lower positive rates for facial CT scans.

Characterization of electro-oxidation catalysts using scanning electrochemical and mass spectral methods

NASA Astrophysics Data System (ADS)

Jambunathan, Krishnakumar

Low temperature fuel cells have many potential benefits, including high efficiency, high energy density and environmental friendliness. However, logistically appealing fuels for this system, such as reformed hydrocarbons or alcohols, exhibit poor performance because of catalyst poisoning that occurs during oxidation at the anode. This research focuses on the analysis of several model fuels and catalyst materials to understand the impact of catalyst poisoning on reactivity. Two novel experimental tools were developed based upon the local measurement of catalyst performance using scanning, reactivity mapping probes. The Scanning Electrochemical Microscope (SECM) was used to directly measure the rate constant for hydrogen oxidation in the presence and absence of dissolved CO. The Scanning Differential Electrochemical Mass Spectrometer (SDEMS) was exploited to measure the partial and complete oxidation products of methanol and ethanol oxidation. The reactivity of Pt and Pt/Ru catalysts towards the hydrogen oxidation reaction in the absence and presence of adsorbed CO was elucidated using the SECM. Steady state rate constant measurements in the absence of CO showed that the rate of hydrogen oxidation reaction exceeded 1 cms-1 . Steady state rate constant measurements in the presence of CO indicated that the platinum surface is completely inactive due to adsorbed CO. Addition of as little as 6% Ru to the Pt electrode was found to significantly improve the activity of the electrode towards CO removal. SDEMS was used to study the electro-oxidation of methanol on Pt xRuy electrodes at different electrode potentials and temperatures. Screening measurements performed with the SDEMS showed that PtxRu y electrodes containing 6--40% Ru had the highest activity for methanol oxidation. Current efficiencies for CO2 were also calculated under different conditions. SDEMS was also used to study the electro-oxidation of ethanol on Pt xRuy electrodes. The reaction was found to occur more slowly than the methanol oxidation reaction. Addition of 22%--40% Ru to the Pt electrode was found to increase the current densities and lower the onset potentials. The reaction was found to occur though a parallel path mechanism, which was confirmed by the detection of ethanol and acetic acid apart from CO2.

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events

PubMed Central

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events. PMID:23823461

High-speed atomic force microscopy combined with inverted optical microscopy for studying cellular events.

PubMed

Suzuki, Yuki; Sakai, Nobuaki; Yoshida, Aiko; Uekusa, Yoshitsugu; Yagi, Akira; Imaoka, Yuka; Ito, Shuichi; Karaki, Koichi; Takeyasu, Kunio

2013-01-01

A hybrid atomic force microscopy (AFM)-optical fluorescence microscopy is a powerful tool for investigating cellular morphologies and events. However, the slow data acquisition rates of the conventional AFM unit of the hybrid system limit the visualization of structural changes during cellular events. Therefore, high-speed AFM units equipped with an optical/fluorescence detection device have been a long-standing wish. Here we describe the implementation of high-speed AFM coupled with an optical fluorescence microscope. This was accomplished by developing a tip-scanning system, instead of a sample-scanning system, which operates on an inverted optical microscope. This novel device enabled the acquisition of high-speed AFM images of morphological changes in individual cells. Using this instrument, we conducted structural studies of living HeLa and 3T3 fibroblast cell surfaces. The improved time resolution allowed us to image dynamic cellular events.

High-dose MVCT image guidance for stereotactic body radiation therapy

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

Westerly, David C.; Schefter, Tracey E.; Kavanagh, Brian D.

Purpose: Stereotactic body radiation therapy (SBRT) is a potent treatment for early stage primary and limited metastatic disease. Accurate tumor localization is essential to administer SBRT safely and effectively. Tomotherapy combines helical IMRT with onboard megavoltage CT (MVCT) imaging and is well suited for SBRT; however, MVCT results in reduced soft tissue contrast and increased image noise compared with kilovoltage CT. The goal of this work was to investigate the use of increased imaging doses on a clinical tomotherapy machine to improve image quality for SBRT image guidance. Methods: Two nonstandard, high-dose imaging modes were created on a tomotherapy machinemore » by increasing the linear accelerator (LINAC) pulse rate from the nominal setting of 80 Hz, to 160 Hz and 300 Hz, respectively. Weighted CT dose indexes (wCTDIs) were measured for the standard, medium, and high-dose modes in a 30 cm solid water phantom using a calibrated A1SL ion chamber. Image quality was assessed from scans of a customized image quality phantom. Metrics evaluated include: contrast-to-noise ratios (CNRs), high-contrast spatial resolution, image uniformity, and percent image noise. In addition, two patients receiving SBRT were localized using high-dose MVCT scans. Raw detector data collected after each scan were used to reconstruct standard-dose images for comparison. Results: MVCT scans acquired using a pitch of 1.0 resulted in wCTDI values of 2.2, 4.7, and 8.5 cGy for the standard, medium, and high-dose modes respectively. CNR values for both low and high-contrast materials were found to increase with the square root of dose. Axial high-contrast spatial resolution was comparable for all imaging modes at 0.5 lp/mm. Image uniformity was improved and percent noise decreased as the imaging dose increased. Similar improvements in image quality were observed in patient images, with decreases in image noise being the most notable. Conclusions: High-dose imaging modes are made possible on a clinical tomotherapy machine by increasing the LINAC pulse rate. Increasing the imaging dose results in increased CNRs; making it easier to distinguish the boundaries of low contrast objects. The imaging dose levels observed in this work are considered acceptable at our institution for SBRT treatments delivered in 3-5 fractions.« less

High-dose MVCT image guidance for stereotactic body radiation therapy.

PubMed

Westerly, David C; Schefter, Tracey E; Kavanagh, Brian D; Chao, Edward; Lucas, Dan; Flynn, Ryan T; Miften, Moyed

2012-08-01

Stereotactic body radiation therapy (SBRT) is a potent treatment for early stage primary and limited metastatic disease. Accurate tumor localization is essential to administer SBRT safely and effectively. Tomotherapy combines helical IMRT with onboard megavoltage CT (MVCT) imaging and is well suited for SBRT; however, MVCT results in reduced soft tissue contrast and increased image noise compared with kilovoltage CT. The goal of this work was to investigate the use of increased imaging doses on a clinical tomotherapy machine to improve image quality for SBRT image guidance. Two nonstandard, high-dose imaging modes were created on a tomotherapy machine by increasing the linear accelerator (LINAC) pulse rate from the nominal setting of 80 Hz, to 160 Hz and 300 Hz, respectively. Weighted CT dose indexes (wCTDIs) were measured for the standard, medium, and high-dose modes in a 30 cm solid water phantom using a calibrated A1SL ion chamber. Image quality was assessed from scans of a customized image quality phantom. Metrics evaluated include: contrast-to-noise ratios (CNRs), high-contrast spatial resolution, image uniformity, and percent image noise. In addition, two patients receiving SBRT were localized using high-dose MVCT scans. Raw detector data collected after each scan were used to reconstruct standard-dose images for comparison. MVCT scans acquired using a pitch of 1.0 resulted in wCTDI values of 2.2, 4.7, and 8.5 cGy for the standard, medium, and high-dose modes respectively. CNR values for both low and high-contrast materials were found to increase with the square root of dose. Axial high-contrast spatial resolution was comparable for all imaging modes at 0.5 lp∕mm. Image uniformity was improved and percent noise decreased as the imaging dose increased. Similar improvements in image quality were observed in patient images, with decreases in image noise being the most notable. High-dose imaging modes are made possible on a clinical tomotherapy machine by increasing the LINAC pulse rate. Increasing the imaging dose results in increased CNRs; making it easier to distinguish the boundaries of low contrast objects. The imaging dose levels observed in this work are considered acceptable at our institution for SBRT treatments delivered in 3-5 fractions.

High-Speed Digital Scan Converter for High-Frequency Ultrasound Sector Scanners

PubMed Central

Chang, Jin Ho; Yen, Jesse T.; Shung, K. Kirk

2008-01-01

This paper presents a high-speed digital scan converter (DSC) capable of providing more than 400 images per second, which is necessary to examine the activities of the mouse heart whose rate is 5–10 beats per second. To achieve the desired high-speed performance in cost-effective manner, the DSC developed adopts a linear interpolation algorithm in which two nearest samples to each object pixel of a monitor are selected and only angular interpolation is performed. Through computer simulation with the Field II program, its accuracy was investigated by comparing it to that of bilinear interpolation known as the best algorithm in terms of accuracy and processing speed. The simulation results show that the linear interpolation algorithm is capable of providing an acceptable image quality, which means that the difference of the root mean square error (RMSE) values of the linear and bilinear interpolation algorithms is below 1 %, if the sample rate of the envelope samples is at least four times higher than the Nyquist rate for the baseband component of echo signals. The designed DSC was implemented with a single FPGA (Stratix EP1S60F1020C6, Altera Corporation, San Jose, CA) on a DSC board that is a part of a high-speed ultrasound imaging system developed. The temporal and spatial resolutions of the implemented DSC were evaluated by examining its maximum processing time with a time stamp indicating when an image is completely formed and wire phantom testing, respectively. The experimental results show that the implemented DSC is capable of providing images at the rate of 400 images per second with negligible processing error. PMID:18430449

In-vivo digital wavefront sensing using swept source OCT

PubMed Central

Kumar, Abhishek; Wurster, Lara M.; Salas, Matthias; Ginner, Laurin; Drexler, Wolfgang; Leitgeb, Rainer A.

2017-01-01

Sub-aperture based digital adaptive optics is demonstrated in a fiber based point scanning optical coherence tomography system using a 1060 nm swept source laser. To detect optical aberrations in-vivo, a small lateral field of view of ~150×150 μm2 is scanned on the sample at a high volume rate of 17 Hz (~1.3 kHz B-scan rate) to avoid any significant lateral and axial motion of the sample, and is used as a “guide star” for the sub-aperture based DAO. The proof of principle is demonstrated using a micro-beads phantom sample, wherein a significant root mean square wavefront error (RMS WFE) of 1.48 waves (> 1μm) is detected. In-vivo aberration measurement with a RMS WFE of 0.33 waves, which is ~5 times higher than the Marechal’s criterion of 1/14 waves for the diffraction limited performance, is shown for a human retinal OCT. Attempt has been made to validate the experimental results with the conventional Shack-Hartmann wavefront sensor within reasonable limitations. PMID:28717573

In Situ Observation of Kinetic Processes of Lath Bainite Nucleation and Growth by Laser Scanning Confocal Microscope in Reheated Weld Metals

NASA Astrophysics Data System (ADS)

Mao, Gaojun; Cao, Rui; Guo, Xili; Jiang, Yong; Chen, Jianhong

2017-12-01

The kinetic processes of nucleation and growth of bainite laths in reheated weld metals are observed and analyzed by a combination of a laser confocal scanning microscope and an electron backscattering diffraction with a field emission scanning electron microscope. The results indicate that the surface relief induced by phase transformation is able to reveal the real microstructural morphologies of bainite laths when viewed from various angles. Five nucleation modes and six types of growth behaviors of bainite laths are revealed. The bainite lath growth rates are measured to vary over a wide range, from 2 μm/s to higher than 2000 μm/s. The orientations of the bainite laths within a prior austenite grain are examined and denoted as different variants. On the basis of variant identification, the reason is analyzed for various growth rates which are demonstrated to be affected by (1) the density of the high-angle misorientation in it, (2) the included angle between habit planes of different variants, and (3) the direction of lath growth with respect to the free (polished) surface.

Dynamic in vivo imaging of small animal brain using pulsed laser diode-based photoacoustic tomography system

NASA Astrophysics Data System (ADS)

Upputuri, Paul Kumar; Pramanik, Manojit

2017-09-01

We demonstrate dynamic in vivo imaging using a low-cost portable pulsed laser diode (PLD)-based photoacoustic tomography system. The system takes advantage of an 803-nm PLD having high-repetition rate ˜7000 Hz combined with a fast-scanning single-element ultrasound transducer leading to a 5 s cross-sectional imaging. Cortical vasculature is imaged in scan time of 5 s with high signal-to-noise ratio ˜48. To examine the ability for dynamic imaging, we monitored the fast uptake and clearance process of indocyanine green in the rat brain. The system will find applications to study neurofunctional activities, characterization of pharmacokinetic, and biodistribution profiles in the development process of drugs or imaging agents.

Native denaturation differential scanning fluorimetry: Determining the effect of urea using a quantitative real-time thermocycler.

PubMed

Childers, Christine L; Green, Stuart R; Dawson, Neal J; Storey, Kenneth B

2016-09-01

The effect of protein stability on kinetic function is monitored with many techniques that often require large amounts of expensive substrates and specialized equipment not universally available. We present differential scanning fluorimetry (DSF), a simple high-throughput assay performed in real-time thermocyclers, as a technique for analysis of protein unfolding. Furthermore, we demonstrate a correlation between the half-maximal rate of protein unfolding (Knd), and protein unfolding by urea (I50). This demonstrates that DSF methods can determine the structural stability of an enzyme's active site and can compare the relative structural stability of homologous enzymes with a high degree of sequence similarity. Copyright © 2016 Elsevier Inc. All rights reserved.

Photon counting photodiode array detector for far ultraviolet (FUV) astronomy

NASA Technical Reports Server (NTRS)

Hartig, G. F.; Moos, H. W.; Pembroke, R.; Bowers, C.

1982-01-01

A compact, stable, single-stage intensified photodiode array detector designed for photon-counting, far ultraviolet astronomy applications employs a saturable, 'C'-type MCP (Galileo S. MCP 25-25) to produce high gain pulses with a narrowly peaked pulse height distribution. The P-20 output phosphor exhibits a very short decay time, due to the high current density of the electron pulses. This intensifier is being coupled to a self-scanning linear photodiode array which has a fiber optic input window which allows direct, rigid mechanical coupling with minimal light loss. The array was scanned at a 250 KHz pixel rate. The detector exhibits more than adequate signal-to-noise ratio for pulse counting and event location. Previously announced in STAR as N82-19118

Active sensing associated with spatial learning reveals memory-based attention in an electric fish

PubMed Central

Longtin, André; Maler, Leonard

2016-01-01

Active sensing behaviors reveal what an animal is attending to and how it changes with learning. Gymnotus sp., a gymnotiform weakly electric fish, generates an electric organ discharge (EOD) as discrete pulses to actively sense its surroundings. We monitored freely behaving gymnotid fish in a large dark “maze” and extracted their trajectories and EOD pulse pattern and rate while they learned to find food with electrically detectable landmarks as cues. After training, they more rapidly found food using shorter, more stereotyped trajectories and spent more time near the food location. We observed three forms of active sensing: sustained high EOD rates per unit distance (sampling density), transient large increases in EOD rate (E-scans) and stereotyped scanning movements (B-scans) were initially strong at landmarks and food, but, after learning, intensified only at the food location. During probe (no food) trials, after learning, the fish's search area and intense active sampling was still centered on the missing food location, but now also increased near landmarks. We hypothesize that active sensing is a behavioral manifestation of attention and essential for spatial learning; the fish use spatial memory of landmarks and path integration to reach the expected food location and confine their attention to this region. PMID:26961107

Active sensing associated with spatial learning reveals memory-based attention in an electric fish.

PubMed

Jun, James J; Longtin, André; Maler, Leonard

2016-05-01

Active sensing behaviors reveal what an animal is attending to and how it changes with learning. Gymnotus sp, a gymnotiform weakly electric fish, generates an electric organ discharge (EOD) as discrete pulses to actively sense its surroundings. We monitored freely behaving gymnotid fish in a large dark "maze" and extracted their trajectories and EOD pulse pattern and rate while they learned to find food with electrically detectable landmarks as cues. After training, they more rapidly found food using shorter, more stereotyped trajectories and spent more time near the food location. We observed three forms of active sensing: sustained high EOD rates per unit distance (sampling density), transient large increases in EOD rate (E-scans) and stereotyped scanning movements (B-scans) were initially strong at landmarks and food, but, after learning, intensified only at the food location. During probe (no food) trials, after learning, the fish's search area and intense active sampling was still centered on the missing food location, but now also increased near landmarks. We hypothesize that active sensing is a behavioral manifestation of attention and essential for spatial learning; the fish use spatial memory of landmarks and path integration to reach the expected food location and confine their attention to this region. Copyright © 2016 the American Physiological Society.

Periodic structures on germanium induced by high repetition rate femtosecond laser

NASA Astrophysics Data System (ADS)

Lin, Xiaoming; Li, Xiaohong; Zhang, Yanbin; Xie, Changxin; Liu, Kaijun; Zhou, Qiang

2018-05-01

Laser-induced periodic surface structures (LIPSS) are studied on germanium surface in air by the femtosecond pulsed laser with repetition frequency of 76 MHz and wavelength λ of 800 nm. Three types of LIPSS were found and they are low-spatial-frequency LIPSS (LSFL), high-spatial-frequency LIPSS (HSFL), and LSFL superimposed with HSFL. The period ΛLSFL of LSFL shrinks quickly from approximately 650 nm to 400 nm (∼λ/2) when lowering the scanning speed. Comparatively, the period ΛHSFL of HSFL keeps almost constant between 90 and 100 nm (∼λ/8) when the scanning speed and the laser pulse energy vary. LSFL and HSFL coexist when the laser pulse energy is around 3.3 nJ/pulse and the scanning speed ranges between 3 and 8 mm/s. The surface plasmon polariton waves make a contribution to the formation of LIPSS and the fourth harmonic generation (FHG) might be involved in the formation of HSFL.

Turboprop+: enhanced Turboprop diffusion-weighted imaging with a new phase correction.

PubMed

Lee, Chu-Yu; Li, Zhiqiang; Pipe, James G; Debbins, Josef P

2013-08-01

Faster periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging acquisitions, such as Turboprop and X-prop, remain subject to phase errors inherent to a gradient echo readout, which ultimately limits the applied turbo factor (number of gradient echoes between each pair of radiofrequency refocusing pulses) and, thus, scan time reductions. This study introduces a new phase correction to Turboprop, called Turboprop+. This technique employs calibration blades, which generate 2-D phase error maps and are rotated in accordance with the data blades, to correct phase errors arising from off-resonance and system imperfections. The results demonstrate that with a small increase in scan time for collecting calibration blades, Turboprop+ had a superior immunity to the off-resonance-related artifacts when compared to standard Turboprop and recently proposed X-prop with the high turbo factor (turbo factor = 7). Thus, low specific absorption rate and short scan time can be achieved in Turboprop+ using a high turbo factor, whereas off-resonance related artifacts are minimized. © 2012 Wiley Periodicals, Inc.

Chemical Fouling Reduction of a Submersible Steel Spectrophotometer in Estuarine Environments Using a Sacrificial Zinc Anode.

PubMed

Tait, Zachary S; Thompson, Megan; Stubbins, Aron

2015-07-01

The availability of in situ spectrophotometers, such as the S::CAN spectro::lyser, has expanded the possibilities for high-frequency water quality data collection. However, biological and chemical fouling can degrade the performance of in situ spectrophotometers, especially in saline environments with rapid flow rates. A complex freshwater washing system has been previously designed to reduce chemical fouling for the S::CAN spectro::lyser spectrophotometer. In the current study, we present a simpler, cheaper alternative: the attachment of a sacrificial zinc anode. Results are presented detailing the S::CAN spectro::lyser performance with and without the addition of the sacrificial anode. Attachment of the zinc anode provided efficient corrosion protection during 2-wk deployments in a highly dynamic (average tidal range, 2.5 m) saline tidal saltmarsh creek at Groves Creek, Skidaway Institute of Oceanography, Savannah, GA. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

The oxidation of aluminum at high temperature studied by Thermogravimetric Analysis and Differential Scanning Calorimetry.

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

Coker, Eric Nicholas

2013-10-01

The oxidation in air of high-purity Al foil was studied as a function of temperature using Thermogravimetric Analysis with Differential Scanning Calorimetry (TGA/DSC). The rate and/or extent of oxidation was found to be a non-linear function of the temperature. Between 650 and 750 ÀC very little oxidation took place; at 850 ÀC oxidation occurred after an induction period, while at 950 ÀC oxidation occurred without an induction period. At oxidation temperatures between 1050 and 1150 ÀC rapid passivation of the surface of the aluminum foil occurred, while at 1250 ÀC and above, an initial rapid mass increase was observed, followedmore » by a more gradual increase in mass. The initial rapid increase was accompanied by a significant exotherm. Cross-sections of oxidized specimens were characterized by scanning electron microscopy (SEM); the observed alumina skin thicknesses correlated qualitatively with the observed mass increases.« less

High prevalence of brain pathology in violent prisoners: a qualitative CT and MRI scan study.

PubMed

Schiltz, Kolja; Witzel, Joachim G; Bausch-Hölterhoff, Josef; Bogerts, Bernhard

2013-10-01

The aim of this study was to determine the frequency and extent of brain anomalies in a large sample of incarcerated violent offenders not previously considered neuropsychiatrically ill, in comparison with non-violent offenders and non-offending controls. MRI and CT brain scans from 287 male prison inmates (162 violent and 125 non-violent) not diagnosed as mentally ill before that were obtained due to headache, vertigo or psychological complaints during imprisonment were assessed and compared to 52 non-criminal controls. Brain scans were rated qualitatively with respect to evidence of structural brain damage. Each case received a semiquantitative rating of "normal" (=0), "questionably abnormal" (=1) or "definitely abnormal" (=2) for the lateral ventricles, frontal/parietal cortex and medial temporal structures bilaterally as well as third ventricle. Overall, offenders displayed a significantly higher rate of morphological abnormality, with the violent offenders scoring significantly higher than non-violent offenders and controls. This difference was statistically detectable for frontal/parietal cortex, medial temporal structures, third ventricle and the left but not the right lateral ventricle. The remarkable prevalence of brain pathology in convicted violent prisoners detectable by neuroradiological routine assessment not only highlights the importance of frontal and temporal structures in the control of social, and specifically of violent behaviour, but also raises questions on the legal culpability of violent offenders with brain abnormalities. The high proportion of undetected presence of structural brain damage emphasizes the need that in violent criminals, the comprehensive routine neuropsychiatric assessment usually performed in routine forensic psychiatric expertises should be complemented with brain imaging.

Novel modes and adaptive block scanning order for intra prediction in AV1

NASA Astrophysics Data System (ADS)

Hadar, Ofer; Shleifer, Ariel; Mukherjee, Debargha; Joshi, Urvang; Mazar, Itai; Yuzvinsky, Michael; Tavor, Nitzan; Itzhak, Nati; Birman, Raz

2017-09-01

The demand for streaming video content is on the rise and growing exponentially. Networks bandwidth is very costly and therefore there is a constant effort to improve video compression rates and enable the sending of reduced data volumes while retaining quality of experience (QoE). One basic feature that utilizes the spatial correlation of pixels for video compression is Intra-Prediction, which determines the codec's compression efficiency. Intra prediction enables significant reduction of the Intra-Frame (I frame) size and, therefore, contributes to efficient exploitation of bandwidth. In this presentation, we propose new Intra-Prediction algorithms that improve the AV1 prediction model and provide better compression ratios. Two (2) types of methods are considered: )1( New scanning order method that maximizes spatial correlation in order to reduce prediction error; and )2( New Intra-Prediction modes implementation in AVI. Modern video coding standards, including AVI codec, utilize fixed scan orders in processing blocks during intra coding. The fixed scan orders typically result in residual blocks with high prediction error mainly in blocks with edges. This means that the fixed scan orders cannot fully exploit the content-adaptive spatial correlations between adjacent blocks, thus the bitrate after compression tends to be large. To reduce the bitrate induced by inaccurate intra prediction, the proposed approach adaptively chooses the scanning order of blocks according to criteria of firstly predicting blocks with maximum number of surrounding, already Inter-Predicted blocks. Using the modified scanning order method and the new modes has reduced the MSE by up to five (5) times when compared to conventional TM mode / Raster scan and up to two (2) times when compared to conventional CALIC mode / Raster scan, depending on the image characteristics (which determines the percentage of blocks predicted with Inter-Prediction, which in turn impacts the efficiency of the new scanning method). For the same cases, the PSNR was shown to improve by up to 7.4dB and up to 4 dB, respectively. The new modes have yielded 5% improvement in BD-Rate over traditionally used modes, when run on K-Frame, which is expected to yield 1% of overall improvement.

Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

NASA Astrophysics Data System (ADS)

Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

2014-06-01

High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

Genomic resources and their influence on the detection of the signal of positive selection in genome scans.

PubMed

Manel, S; Perrier, C; Pratlong, M; Abi-Rached, L; Paganini, J; Pontarotti, P; Aurelle, D

2016-01-01

Genome scans represent powerful approaches to investigate the action of natural selection on the genetic variation of natural populations and to better understand local adaptation. This is very useful, for example, in the field of conservation biology and evolutionary biology. Thanks to Next Generation Sequencing, genomic resources are growing exponentially, improving genome scan analyses in non-model species. Thousands of SNPs called using Reduced Representation Sequencing are increasingly used in genome scans. Besides, genome sequences are also becoming increasingly available, allowing better processing of short-read data, offering physical localization of variants, and improving haplotype reconstruction and data imputation. Ultimately, genome sequences are also becoming the raw material for selection inferences. Here, we discuss how the increasing availability of such genomic resources, notably genome sequences, influences the detection of signals of selection. Mainly, increasing data density and having the information of physical linkage data expand genome scans by (i) improving the overall quality of the data, (ii) helping the reconstruction of demographic history for the population studied to decrease false-positive rates and (iii) improving the statistical power of methods to detect the signal of selection. Of particular importance, the availability of a high-quality reference genome can improve the detection of the signal of selection by (i) allowing matching the potential candidate loci to linked coding regions under selection, (ii) rapidly moving the investigation to the gene and function and (iii) ensuring that the highly variable regions of the genomes that include functional genes are also investigated. For all those reasons, using reference genomes in genome scan analyses is highly recommended. © 2015 John Wiley & Sons Ltd.

Identification-While-Scanning of a Multi-Aircraft Formation Based on Sparse Recovery for Narrowband Radar.

PubMed

Jiang, Yuan; Xu, Jia; Peng, Shi-Bao; Mao, Er-Ke; Long, Teng; Peng, Ying-Ning

2016-11-23

It is known that the identification performance of a multi-aircraft formation (MAF) of narrowband radar mainly depends on the time on target (TOT). To realize the identification task in one rotated scan with limited TOT, the paper proposes a novel identification-while-scanning (IWS) method based on sparse recovery to maintain high rotating speed and super-resolution for MAF identification, simultaneously. First, a multiple chirp signal model is established for MAF in a single scan, where different aircraft may have different Doppler centers and Doppler rates. Second, based on the sparsity of MAF in the Doppler parameter space, a novel hierarchical basis pursuit (HBP) method is proposed to obtain satisfactory sparse recovery performance as well as high computational efficiency. Furthermore, the parameter estimation performance of the proposed IWS identification method is analyzed with respect to recovery condition, signal-to-noise ratio and TOT. It is shown that an MAF can be effectively identified via HBP with a TOT of only about one hundred microseconds for IWS applications. Finally, some numerical experiment results are provided to demonstrate the effectiveness of the proposed method based on both simulated and real measured data.

X-PROP: a fast and robust diffusion-weighted propeller technique.

PubMed

Li, Zhiqiang; Pipe, James G; Lee, Chu-Yu; Debbins, Josef P; Karis, John P; Huo, Donglai

2011-08-01

Diffusion-weighted imaging (DWI) has shown great benefits in clinical MR exams. However, current DWI techniques have shortcomings of sensitivity to distortion or long scan times or combinations of the two. Diffusion-weighted echo-planar imaging (EPI) is fast but suffers from severe geometric distortion. Periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging (PROPELLER DWI) is free of geometric distortion, but the scan time is usually long and imposes high Specific Absorption Rate (SAR) especially at high fields. TurboPROP was proposed to accelerate the scan by combining signal from gradient echoes, but the off-resonance artifacts from gradient echoes can still degrade the image quality. In this study, a new method called X-PROP is presented. Similar to TurboPROP, it uses gradient echoes to reduce the scan time. By separating the gradient and spin echoes into individual blades and removing the off-resonance phase, the off-resonance artifacts in X-PROP are minimized. Special reconstruction processes are applied on these blades to correct for the motion artifacts. In vivo results show its advantages over EPI, PROPELLER DWI, and TurboPROP techniques. Copyright © 2011 Wiley-Liss, Inc.

1-mm catheterscope

NASA Astrophysics Data System (ADS)

Seibel, Eric J.

2008-02-01

Flexible endoscopes use one sensor element per display pixel. When diameter is reduced to the size of a catheter, there is a significant reduction in the number of pixels within the image. By placing a sub-millimeter microscanner at the tip of a catheter, image quality can be significantly improved. The microscanner consists of a 0.4 mm diameter piezoelectric tube with quadrant electrodes, surrounding a cantilevered singlemode optical fiber. At the distal end, the fiber microscanner is sealed with a 0.9 mm diameter lens assembly, creating a rigid length less than 10 mm at the tip of a highly flexible shaft. The cantilevered fiber is vibrated at the first mode of resonance for bending to generate a circular scan pattern. A spiral scan pattern is generated that constitutes an image frame by modulating the piezoelectric drive signals. By using a custom optical fiber at 80 microns cladding diameter, >10 KHz resonant scanning is achieved, resulting in a 30 Hz frame rate. Red (635 nm), green (532 nm), and blue (442 nm) laser light is scanned by coupling to the fiber scanner. The scanned illumination is detected in a non-confocal arrangement by having one or more optical fibers collecting the backscattered light at MHz pixel rates. Current 1-mm diameter catheterscopes generate 500-line images at maximum fields of view of 100 degrees and spatial resolutions of <20 microns with image zooming. Shaft length of four meters have been fabricated with flexibility of <10 mm bending radius to image previously inaccessible regions of the body.

Towards ultrahigh resting-state functional connectivity in the mouse brain using photoacoustic microscopy

NASA Astrophysics Data System (ADS)

Hariri, Ali; Bely, Nicholas; Chen, Chen; Nasiriavanaki, Mohammadreza

2016-03-01

The increasing use of mouse models for human brain disease studies, coupled with the fact that existing high-resolution functional imaging modalities cannot be easily applied to mice, presents an emerging need for a new functional imaging modality. Utilizing both mechanical and optical scanning in the photoacoustic microscopy, we can image spontaneous cerebral hemodynamic fluctuations and their associated functional connections in the mouse brain. The images is going to be acquired noninvasively with a fast frame rate, a large field of view, and a high spatial resolution. We developed an optical resolution photoacoustic microscopy (OR-PAM) with diode laser. Laser light was raster scanned due to XY-stage movement. Images from ultra-high OR-PAM can then be used to study brain disorders such as stroke, Alzheimer's, schizophrenia, multiple sclerosis, autism, and epilepsy.

LiCoPO4 cathode from a CoHPO4·xH2O nanoplate precursor for high voltage Li-ion batteries

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

Choi, Daiwon; Li, Xiaolin; Henderson, Wesley A.

2016-02-01

Highly crystalline LiCoPO4/C cathode has been synthesized without any impurities via single step solid-state reaction using CoHPO4xH2O nanoplates as a precursor obtained by simple precipitation route. The electrochemical test shows specific capacity as high as 125mAh/g at charge/discharge rate of C/10. Synthesis approach for obtaining CoHPO4xH2O nanoplate precursor and final LiCoPO4/C cathode using single step solid-state reaction have been characterized using X-ray diffraction, thermos gravimetric analyses (TGA) – differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The electrochemical test and cycling stability using different electrolytes, additive and separator have been investigated.

High rate tests of the photon detection system for the LHCb RICH Upgrade

NASA Astrophysics Data System (ADS)

Blago, M. P.; Keizer, F.

2017-12-01

The photon detection system for the LHCb RICH Upgrade consists of an array of multianode photomultiplier tubes (MaPMTs) read out by custom-built modular electronics. The behaviour of the whole chain was studied at CERN using a pulsed laser. Threshold scans were performed in order to study the MaPMT pulse-height spectra at high event rates and different photon intensities. The results show a reduction in photon detection efficiency at 900 V bias voltage, marked by a 20% decrease in the single-photon peak height, when increasing the event rate from 100 kHz to 20 MHz. This reduction was not observed at 1000 V bias voltage.

Efficacious insect and disease control with laser-guided air-assisted sprayer

USDA-ARS?s Scientific Manuscript database

Efficacy of a newly developed air-assisted variable-rate sprayer was investigated for the control of arthropod pests and plant diseases in six commercial fields. The sprayer was integrated with a high-speed laser scanning sensor, a custom-designed signal processing program, an automatic flow control...

Development of LIDAR-guided sprayer to synchronize spray outputs with canopy structures

USDA-ARS?s Scientific Manuscript database

Variable-rate application is an effective way for nursery and orchard growers to reduce pesticide use and potential contaminations to the environment. To realize this goal, an intelligent air-assisted sprayer implementing a high speed laser scanning sensor (LIDAR) was developed to vary spray output ...

Mass loss in red giants and supergiants

NASA Technical Reports Server (NTRS)

Sanner, F.

1976-01-01

The circumstellar envelopes surrounding 13 late-type giants and supergiants have been studied using a homogeneous collection of high-resolution, photoelectric scans of strong optical resonance lines. Various properties of the envelopes, including the mass loss rate, dilution factor, hydrogen density, and degree of ionization, have been determined quantitatively.

Do thallium myocardial perfusion scan abnormalities predict survival in sarcoid patients without cardiac symptoms

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

Kinney, E.L.; Caldwell, J.W.

1990-07-01

Whereas the total mortality rate for sarcoidosis is 0.2 per 100,000, the prognosis, when the heart is involved, is very much worse. The authors used the difference in mortality rate to infer whether thallium 201 myocardial perfusion scan abnormalities correspond to myocardial sarcoid by making the simplifying assumption that if they do, then patients with abnormal scans will be found to have a death rate similar to patients with sarcoid heart disease. The authors therefore analyzed complete survival data on 52 sarcoid patients without cardiac symptoms an average of eighty-nine months after they had been scanned as part of amore » protocol. By use of survival analysis (the Cox proportional hazards model), the only variable that was significantly associated with survival was age. The patients' scan pattern, treatment status, gender, and race were not significantly related to survival. The authors conclude that thallium myocardial perfusion scans cannot reliably be used to diagnose sarcoid heart disease in sarcoid patients without cardiac symptoms.« less

Rapid-scan EPR imaging.

PubMed

Eaton, Sandra S; Shi, Yilin; Woodcock, Lukas; Buchanan, Laura A; McPeak, Joseph; Quine, Richard W; Rinard, George A; Epel, Boris; Halpern, Howard J; Eaton, Gareth R

2017-07-01

In rapid-scan EPR the magnetic field or frequency is repeatedly scanned through the spectrum at rates that are much faster than in conventional continuous wave EPR. The signal is directly-detected with a mixer at the source frequency. Rapid-scan EPR is particularly advantageous when the scan rate through resonance is fast relative to electron spin relaxation rates. In such scans, there may be oscillations on the trailing edge of the spectrum. These oscillations can be removed by mathematical deconvolution to recover the slow-scan absorption spectrum. In cases of inhomogeneous broadening, the oscillations may interfere destructively to the extent that they are not visible. The deconvolution can be used even when it is not required, so spectra can be obtained in which some portions of the spectrum are in the rapid-scan regime and some are not. The technology developed for rapid-scan EPR can be applied generally so long as spectra are obtained in the linear response region. The detection of the full spectrum in each scan, the ability to use higher microwave power without saturation, and the noise filtering inherent in coherent averaging results in substantial improvement in signal-to-noise relative to conventional continuous wave spectroscopy, which is particularly advantageous for low-frequency EPR imaging. This overview describes the principles of rapid-scan EPR and the hardware used to generate the spectra. Examples are provided of its application to imaging of nitroxide radicals, diradicals, and spin-trapped radicals at a Larmor frequency of ca. 250MHz. Copyright © 2017 Elsevier Inc. All rights reserved.

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

Chen, L.; McGruer, N. E.; Adams, G. G.

We report the observation of two distinct modes of rate-dependent behavior during contact cycling tests. One is a higher pull-off force at low cycling rates and the other is a higher pull-off force at high cycling rates. Subsequent investigation of these contacts using scanning electron microscopy (SEM) demonstrates that these two rate-dependent modes can be related to brittle and ductile separation modes. The former behavior is indicative of brittle separation, whereas the latter accompanies ductile separation. Thus by monitoring the rate dependence of the pull-off force, the type of separation mode can be identified during cycling without interrupting the testmore » to perform SEM.« less

Time-resolved coherent Raman spectroscopy by high-speed pump-probe delay scanning.

PubMed

Domingue, S R; Winters, D G; Bartels, R A

2014-07-15

Using a spinning window pump-probe delay scanner, we demonstrate a means of acquiring time-resolved vibrational spectra at rates up to 700 Hz. The time-dependent phase shift accumulated by the probe pulse in the presence of a coherently vibrating sample gives rise to a Raman-induced frequency shifting readily detectable in a balanced detector. This rapid delay scanning system represents a 23-fold increase in averaging speed and is >10× faster than state-of-the-art voice coil delay lines. These advancements make pump-probe spectroscopy a more practical means of imaging complex media.

Fast, High-Resolution Terahertz Radar Imaging at 25 Meters

NASA Technical Reports Server (NTRS)

Cooper, Ken B.; Dengler, Robert J.; Llombart, Nuria; Talukder, Ashit; Panangadan, Anand V.; Peay, Chris S.; Siegel, Peter H.

2010-01-01

We report improvements in the scanning speed and standoff range of an ultra-wide bandwidth terahertz (THz) imaging radar for person-borne concealed object detection. Fast beam scanning of the single-transceiver radar is accomplished by rapidly deflecting a flat, light-weight subreflector in a confocal Gregorian optical geometry. With RF back-end improvements also implemented, the radar imaging rate has increased by a factor of about 30 compared to that achieved previously in a 4 m standoff prototype instrument. In addition, a new 100 cm diameter ellipsoidal aluminum reflector yields beam spot diameters of approximately 1 cm over a 50x50 cm field of view at a range of 25 m, although some aberrations are observed that probably arise from misaligned optics. Through-clothes images of a concealed threat at 25 m range, acquired in 5 seconds, are presented, and the impact of reduced signal-to-noise from an even faster frame rate is analyzed. These results inform the system requirements for eventually achieving sub-second or video-rate THz radar imaging.

Understanding the crack formation of graphite particles in cycled commercial lithium-ion batteries by focused ion beam - scanning electron microscopy

NASA Astrophysics Data System (ADS)

Lin, Na; Jia, Zhe; Wang, Zhihui; Zhao, Hui; Ai, Guo; Song, Xiangyun; Bai, Ying; Battaglia, Vincent; Sun, Chengdong; Qiao, Juan; Wu, Kai; Liu, Gao

2017-10-01

The structure degradation of commercial Lithium-ion battery (LIB) graphite anodes with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystalline graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.

Preparation and Physicochemical Properties of 10-Hydroxycamptothecin (HCPT) Nanoparticles by Supercritical Antisolvent (SAS) Process

PubMed Central

Zhao, Xiuhua; Zu, Yuangang; Jiang, Ru; Wang, Ying; Li, Yong; Li, Qingyong; Zhao, Dongmei; Zu, Baishi; Zhang, Baoyou; Sun, Zhiqiang; Zhang, Xiaonan

2011-01-01

The goal of the present work was to study the feasibility of 10-hydroxycamptothecin (HCPT) nanoparticle preparation using supercritical antisolvent (SAS) precipitation. The influences of various experimental factors on the mean particle size (MPS) of HCPT nanoparticles were investigated. The optimum micronization conditions are determined as follows: HCPT solution concentration 0.5 mg/mL, the flow rate ratio of CO2 and HCPT solution 19.55, precipitation temperature 35 °C and precipitation pressure 20 MPa. Under the optimum conditions, HCPT nanoparticles with a MPS of 180 ± 20.3 nm were obtained. Moreover, the HCPT nanoparticles obtained were characterized by Scanning electron microscopy, Dynamic light scattering, Fourier-transform infrared spectroscopy, High performance liquid chromatography-mass spectrometry, X-ray diffraction and Differential scanning calorimetry analyses. The physicochemical characterization results showed that the SAS process had not induced degradation of HCPT. Finally, the dissolution rates of HCPT nanoparticles were investigated and the results proved that there is a significant increase in dissolution rate compared to unprocessed HCPT. PMID:21731466

High-speed line-scan camera with digital time delay integration

NASA Astrophysics Data System (ADS)

Bodenstorfer, Ernst; Fürtler, Johannes; Brodersen, Jörg; Mayer, Konrad J.; Eckel, Christian; Gravogl, Klaus; Nachtnebel, Herbert

2007-02-01

Dealing with high-speed image acquisition and processing systems, the speed of operation is often limited by the amount of available light, due to short exposure times. Therefore, high-speed applications often use line-scan cameras, based on charge-coupled device (CCD) sensors with time delayed integration (TDI). Synchronous shift and accumulation of photoelectric charges on the CCD chip - according to the objects' movement - result in a longer effective exposure time without introducing additional motion blur. This paper presents a high-speed color line-scan camera based on a commercial complementary metal oxide semiconductor (CMOS) area image sensor with a Bayer filter matrix and a field programmable gate array (FPGA). The camera implements a digital equivalent to the TDI effect exploited with CCD cameras. The proposed design benefits from the high frame rates of CMOS sensors and from the possibility of arbitrarily addressing the rows of the sensor's pixel array. For the digital TDI just a small number of rows are read out from the area sensor which are then shifted and accumulated according to the movement of the inspected objects. This paper gives a detailed description of the digital TDI algorithm implemented on the FPGA. Relevant aspects for the practical application are discussed and key features of the camera are listed.

Use of a spatial scan statistic to identify clusters of births occurring outside Ghanaian health facilities for targeted intervention.

PubMed

Bosomprah, Samuel; Dotse-Gborgbortsi, Winfred; Aboagye, Patrick; Matthews, Zoe

2016-11-01

To identify and evaluate clusters of births that occurred outside health facilities in Ghana for targeted intervention. A retrospective study was conducted using a convenience sample of live births registered in Ghanaian health facilities from January 1 to December 31, 2014. Data were extracted from the district health information system. A spatial scan statistic was used to investigate clusters of home births through a discrete Poisson probability model. Scanning with a circular spatial window was conducted only for clusters with high rates of such deliveries. The district was used as the geographic unit of analysis. The likelihood P value was estimated using Monte Carlo simulations. Ten statistically significant clusters with a high rate of home birth were identified. The relative risks ranged from 1.43 ("least likely" cluster; P=0.001) to 1.95 ("most likely" cluster; P=0.001). The relative risks of the top five "most likely" clusters ranged from 1.68 to 1.95; these clusters were located in Ashanti, Brong Ahafo, and the Western, Eastern, and Greater regions of Accra. Health facility records, geospatial techniques, and geographic information systems provided locally relevant information to assist policy makers in delivering targeted interventions to small geographic areas. Copyright © 2016 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved.

An intelligent control scheme for precise tip-motion control in atomic force microscopy.

PubMed

Wang, Yanyan; Hu, Xiaodong; Xu, Linyan

2016-01-01

The paper proposes a new intelligent control method to precisely control the tip motion of the atomic force microscopy (AFM). The tip moves up and down at a high rate along the z direction during scanning, requiring the utilization of a rapid feedback controller. The standard proportional-integral (PI) feedback controller is commonly used in commercial AFMs to enable topography measurements. The controller's response performance is determined by the set of the proportional (P) parameter and the integral (I) parameter. However, the two parameters cannot be automatically altered simultaneously according to the scanning speed and the surface topography during continuors scanning, leading to an inaccurate measurement. Thus a new intelligent controller combining the fuzzy controller and the PI controller is put forward in the paper. The new controller automatically selects the most appropriate PI parameters to achieve a fast response rate on basis of the tracking errors. In the experimental setup, the new controller is realized with a digital signal process (DSP) system, implemented in a conventional AFM system. Experiments are carried out by comparing the new method with the standard PI controller. The results demonstrate that the new method is more robust and effective for the precise tip motion control, corresponding to the achievement of a highly qualified image by shortening the response time of the controller. © Wiley Periodicals, Inc.

Transparent, flexible, and high-performance supercapacitor based on ultrafine nickel cobaltite nanospheres

NASA Astrophysics Data System (ADS)

Liu, Xinyue; Wang, Jianxing; Yang, Guowei

2017-07-01

There has been growing interest in transparent and flexible electronic devices such as wrist watch, cell phone, and so on. These devices need the power sources which also have transparent and flexible features. Here, we demonstrate a transparent and flexible energy storage device with outstanding electrochemical performance, high energy density, and super-long life based on ultrafine NiCo2O4 nanospheres which are synthesized by an innovative method concerning laser ablation in liquid and hydrothermal process. The ultrafine NiCo2O4 nanospheres provide high electrochemical activity and the synthesized colloidal solution is suitable for transparent devices. The transparent and flexible device shows a high specific capacitance of 299.7 F/g at the scan rate of 1 mV/s and a long cycling life of 90.4% retention rate after 10,000 cycles at a scan rate of 10 mV/s, which is superior to that of previously reported transparent and flexible energy storage device. In addition, an optical transmittance up to 55% at the wavelength of 550 nm is obtained, and the bending test shows that the bending angle makes no difference to the specific capacitance of the device. In addition, it shows an outstanding energy density of 10.41 Wh/kg. The integrated electrochemical performances of the device are good based on NiCo2O4 nanospheres. These findings make the ultrafine NiCo2O4 nanospheres being promising electrode materials for transparent and flexible energy storage devices.

Evaluating the risk of appendiceal perforation when using ultrasound as the initial diagnostic imaging modality in children with suspected appendicitis.

PubMed

Alerhand, Stephen; Meltzer, James; Tay, Ee Tein

2017-08-01

Ultrasound scan has gained attention for diagnosing appendicitis due to its avoidance of ionizing radiation. However, studies show that ultrasound scan carries inferior sensitivity to computed tomography scan. A non-diagnostic ultrasound scan could increase the time to diagnosis and appendicectomy, particularly if follow-up computed tomography scan is needed. Some studies suggest that delaying appendicectomy increases the risk of perforation. To investigate the risk of appendiceal perforation when using ultrasound scan as the initial diagnostic imaging modality in children with suspected appendicitis. We retrospectively reviewed 1411 charts of children ≤17 years old diagnosed with appendicitis at two urban academic medical centers. Patients who underwent ultrasound scan first were compared to those who underwent computed tomography scan first. In the sub-group analysis, patients who only received ultrasound scan were compared to those who received initial ultrasound scan followed by computed tomography scan. Main outcome measures were appendiceal perforation rate and time from triage to appendicectomy. In 720 children eligible for analysis, there was no significant difference in perforation rate between those who had initial ultrasound scan and those who had initial computed tomography scan (7.3% vs. 8.9%, p = 0.44), nor in those who had ultrasound scan only and those who had initial ultrasound scan followed by computed tomography scan (8.0% vs. 5.6%, p = 0.42). Those patients who had ultrasound scan first had a shorter triage-to-incision time than those who had computed tomography scan first (9.2 (IQR: 5.9, 14.0) vs. 10.2 (IQR: 7.3, 14.3) hours, p = 0.03), whereas those who had ultrasound scan followed by computed tomography scan took longer than those who had ultrasound scan only (7.8 (IQR: 5.3, 11.6) vs. 15.1 (IQR: 10.6, 20.6), p < 0.001). Children < 12 years old receiving ultrasound scan first had lower perforation rate (p = 0.01) and shorter triage-to-incision time (p = 0.003). Children with suspected appendicitis receiving ultrasound scan as the initial diagnostic imaging modality do not have increased risk of perforation compared to those receiving computed tomography scan first. We recommend that children <12 years of age receive ultrasound scan first.

Performance characteristics and relationship of PSA value/kinetics on carbon-11 acetate PET/CT imaging in biochemical relapse of prostate cancer.

PubMed

Almeida, Fabio D; Yen, Chi-Kwan; Scholz, Mark C; Lam, Richard Y; Turner, Jeffrey; Bans, Larry L; Lipson, Robert

2017-01-01

An elevated serum prostate-specific antigen (PSA) level alone cannot distinguish between local-regional recurrences and distant metastases after treatment with curative intent. With available salvage treatments, it has become important to localize the site of recurrence. 11 C-Acetate PET/CT was performed in patients with rising PSA, with statistical analysis of detection rates, sites/location of detection, PSA kinetics and comparison with other tracers (FDG and Choline). Correlation to biopsy, subsequent imaging and PSA response to focal treatment was also performed. 88% (637) of 721 11 C-Acetate PET/CT scans performed were positive. There was a statistically significant difference in PSA values between the positive and negative scans (P < 0.001 for mean difference) with the percentage of positive scans and PSA having a positive correlation. A PSA of 1.09 ng/mL was found to be an optimal cutoff. PSAdT was significantly correlated with a positive scan only when the PSA was < 1.0 ng/mL. For this subgroup, a PSAdT of < 3.8 months appeared significant (P < 0.05) as an optimal cutoff point. 11 C-Acetate PET/CT demonstrates a high detection rate for the site of recurrence/metastasis in biochemical relapsed prostate cancer (88% overall detection rate, PPV 90.8%). This analysis suggests an optimal PSA threshold of > 1.09 ng/mL or a PSAdT of < 3.8 months when the PSA is below 1.0 ng/mL as independent predictors of positive findings.

Mild chemical strategy to grow micro-roses and micro-woolen like arranged CuO nanosheets for high performance supercapacitors

NASA Astrophysics Data System (ADS)

Dubal, Deepak P.; Gund, Girish S.; Holze, Rudolf; Lokhande, Chandrakant D.

2013-11-01

The hierarchical structures of nanosheets, micro-roses and micro-woolen like CuO nanosheets were directly fabricated on stainless steel via surfactant-free and inexpensive chemical bath deposition (CBD) method. Further, these CuO nanostructures demonstrate excellent surface properties like uniform surface morphology, high surface area and uniform pore size distribution of CuO samples. The electrochemical properties of CuO nanostructures have been investigated by cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy techniques. The electrochemical studies of the CuO samples show obvious influence of surface properties on the pseudocapacitance performance. The maximum specific capacitances of nanosheets, micro-roses and micro-woolen like CuO nanosheets are found to be 303 Fg-1, 279 Fg-1 and 346 Fg-1, respectively at 5 mV s-1 scan rate. Further, the EIS analysis shows lower ESR value, high power performance, excellent rate as well as frequency response of micro-woolen like CuO sample. The Ragone plot ascertains better power and energy densities of all three CuO nanostructured samples than other electrical energy storage devices. The long-term cycling performance of CuO is examined at different scan rates and the morphology changes of the electrode materials were studied. Present investigation suggests the inexpensive CBD approach for fine-tuning surface properties of oxide materials for energy storage applications.

[Experiences with power-injectable port systems: complications, patient satisfaction and clinical benefit].

PubMed

Chang, D-H; Kabbasch, C; Bovenschulte, H; Libicher, M; Maintz, D; Bangard, C

2013-05-01

Evaluation of complications, patient satisfaction and clinical benefit of port systems with authorization for high pressure injection of contrast agent during CT/MR examinations. Ultrasound-guided insertions of central venous port catheters were performed through the lateral subclavian vein at a university teaching hospital. The radiological information system (HIS/RIS) was used to evaluate technical success and complication rates. Assessment of patient satisfaction and clinical benefit was carried out by a questionnaire during a telephone call 6 months after implantation of the port system. A total of 195 port systems in 193 patients were implanted. The catheter remained in place for a mean duration of 169 days (overall 29,210 catheter days). The technical success rate was 99.5 % and the overall complication rate was 17.4 % (24/138; 0.82 per 1000 catheter days). Follow-up revealed 13 early port explantations (9 %). Most of the patients reported high satisfaction in general (satisfied/very satisfied: 94 %). 34/209 contrast-enhanced CT/MRT scans (16 %) were performed using the port for contrast media injection. There were no complications during or after administration of contrast agent via the port system. The Powerport system is a safe alternative for peripheral i. v. contrast media injection during CT/MR scans, but has been infrequently used. Most patients reported high overall satisfaction with the port system. © Georg Thieme Verlag KG Stuttgart · New York.

Precipitation Rate Investigation on synthesis of precipitated calcium carbonate

NASA Astrophysics Data System (ADS)

Sulistiyono, E.; Handayani, M.; Firdiyono, F.; Fajariani, E. N.

2018-03-01

Study on the formation of precipitated calcium carbonate from natural limestone Sukabumi with the influenced of various parameters such as precipitation rate, concentration of CaCl2 and amplitudes were investigated. We also investigated the result with the precipitated calcium carbonate from Merck (p.a) for comparison. The higher concentration of CaCl2 would give effect to the lower of the precipitation rate. It was observed that precipitation rate of calcium carbonate from limestone Sukabumi at concentration of 0.08 molar was 3.66 cm/minutes and showing the optimum condition, while the precipitation rate of calcium carbonate Merck at the concentration 0.08 molar was 3.53 cm/minutes. The characterization of precipitated calcium carbonate was done using X-ray fluorescence (XRF) and scanning electron microscope (SEM). The characterization using XRF showed that CaO content of precipitated calcium carbonate from natural limestone Sukabumi had high purity of 99.16%. The particle distribution using scanning electron microscope (SEM) showed that precipitated calcium carbonate from natural limestone Sukabumi revealed 1.79 µm – 11.46 µm, meanwhile the particle distribution of precipitated calcium carbonate Merck showed larger particles with the size of 3.22 µm – 10.68 µm.

Wind Measurements from Arc Scans with Doppler Wind Lidar

DOE PAGES

Wang, H.; Barthelmie, R. J.; Clifton, Andy; ...

2015-11-25

When defining optimal scanning geometries for scanning lidars for wind energy applications, we found that it is still an active field of research. Our paper evaluates uncertainties associated with arc scan geometries and presents recommendations regarding optimal configurations in the atmospheric boundary layer. The analysis is based on arc scan data from a Doppler wind lidar with one elevation angle and seven azimuth angles spanning 30° and focuses on an estimation of 10-min mean wind speed and direction. When flow is horizontally uniform, this approach can provide accurate wind measurements required for wind resource assessments in part because of itsmore » high resampling rate. Retrieved wind velocities at a single range gate exhibit good correlation to data from a sonic anemometer on a nearby meteorological tower, and vertical profiles of horizontal wind speed, though derived from range gates located on a conical surface, match those measured by mast-mounted cup anemometers. Uncertainties in the retrieved wind velocity are related to high turbulent wind fluctuation and an inhomogeneous horizontal wind field. Moreover, the radial velocity variance is found to be a robust measure of the uncertainty of the retrieved wind speed because of its relationship to turbulence properties. It is further shown that the standard error of wind speed estimates can be minimized by increasing the azimuthal range beyond 30° and using five to seven azimuth angles.« less

Flexible pillared graphene-paper electrodes for high-performance electrochemical supercapacitors.

PubMed

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan; Sun, Hongtao; Yu, Mingpeng; Jiang, Weilin; Liu, Changsheng; Lian, Jie

2012-02-06

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s(-1) , the specific capacitance of the pillared GP is 138 F g(-1) and 83.2 F g(-1) with negligible 3.85% and 4.35% capacitance degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s (-1) , the specific capacitance can reach 80 F g(-1) in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. The pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Flexible Pillared Graphene-Paper Electrodes for High-Performance Electrochemical Supercapacitors

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

Wang, Gongkai; Sun, Xiang; Lu, Fengyuan

2011-12-08

Flexible graphene paper (GP) pillared by carbon black (CB) nanoparticles using a simple vacuum filtration method is developed as a high-performance electrode material for supercapacitors. Through the introduction of CB nanoparticles as spacers, the self-restacking of graphene sheets during the filtration process is mitigated to a great extent. The pillared GP-based supercapacitors exhibit excellent electrochemical performances and cyclic stabilities compared with GP without the addition of CB nanoparticles. At a scan rate of 10 mV s -1, the specific capacitance of the pillared GP is 138 F g -1 and 83.2 F g -1 with negligible 3.85% and 4.35% capacitancemore » degradation after 2000 cycles in aqueous and organic electrolytes, respectively. At an extremely fast scan rate of 500 mV s -1, the specific capacitance can reach 80 F g -1 in aqueous electrolyte. No binder is needed for assembling the supercapacitor cells and the pillared GP itself may serve as a current collector due to its intrinsic high electrical conductivity. Finally, the pillared GP has great potential in the development of promising flexible and ultralight-weight supercapacitors for electrochemical energy storage.« less

High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second

PubMed Central

An, Lin; Li, Peng; Shen, Tueng T.; Wang, Ruikang

2011-01-01

We present a new development of ultrahigh speed spectral domain optical coherence tomography (SDOCT) for human retinal imaging at 850 nm central wavelength by employing two high-speed line scan CMOS cameras, each running at 250 kHz. Through precisely controlling the recording and reading time periods of the two cameras, the SDOCT system realizes an imaging speed at 500,000 A-lines per second, while maintaining both high axial resolution (~8 μm) and acceptable depth ranging (~2.5 mm). With this system, we propose two scanning protocols for human retinal imaging. The first is aimed to achieve isotropic dense sampling and fast scanning speed, enabling a 3D imaging within 0.72 sec for a region covering 4x4 mm2. In this case, the B-frame rate is 700 Hz and the isotropic dense sampling is 500 A-lines along both the fast and slow axes. This scanning protocol minimizes the motion artifacts, thus making it possible to perform two directional averaging so that the signal to noise ratio of the system is enhanced while the degradation of its resolution is minimized. The second protocol is designed to scan the retina in a large field of view, in which 1200 A-lines are captured along both the fast and slow axes, covering 10 mm2, to provide overall information about the retinal status. Because of relatively long imaging time (4 seconds for a 3D scan), the motion artifact is inevitable, making it difficult to interpret the 3D data set, particularly in a way of depth-resolved en-face fundus images. To mitigate this difficulty, we propose to use the relatively high reflecting retinal pigmented epithelium layer as the reference to flatten the original 3D data set along both the fast and slow axes. We show that the proposed system delivers superb performance for human retina imaging. PMID:22025983

High speed spectral domain optical coherence tomography for retinal imaging at 500,000 A‑lines per second.

PubMed

An, Lin; Li, Peng; Shen, Tueng T; Wang, Ruikang

2011-10-01

We present a new development of ultrahigh speed spectral domain optical coherence tomography (SDOCT) for human retinal imaging at 850 nm central wavelength by employing two high-speed line scan CMOS cameras, each running at 250 kHz. Through precisely controlling the recording and reading time periods of the two cameras, the SDOCT system realizes an imaging speed at 500,000 A-lines per second, while maintaining both high axial resolution (~8 μm) and acceptable depth ranging (~2.5 mm). With this system, we propose two scanning protocols for human retinal imaging. The first is aimed to achieve isotropic dense sampling and fast scanning speed, enabling a 3D imaging within 0.72 sec for a region covering 4x4 mm(2). In this case, the B-frame rate is 700 Hz and the isotropic dense sampling is 500 A-lines along both the fast and slow axes. This scanning protocol minimizes the motion artifacts, thus making it possible to perform two directional averaging so that the signal to noise ratio of the system is enhanced while the degradation of its resolution is minimized. The second protocol is designed to scan the retina in a large field of view, in which 1200 A-lines are captured along both the fast and slow axes, covering 10 mm(2), to provide overall information about the retinal status. Because of relatively long imaging time (4 seconds for a 3D scan), the motion artifact is inevitable, making it difficult to interpret the 3D data set, particularly in a way of depth-resolved en-face fundus images. To mitigate this difficulty, we propose to use the relatively high reflecting retinal pigmented epithelium layer as the reference to flatten the original 3D data set along both the fast and slow axes. We show that the proposed system delivers superb performance for human retina imaging.

Renal Abnormalities Among Egyptian Children With Hemophilia A Using Renal Scintigraphy: Relation to Risk Factors and Disease Severity.

PubMed

Hamed, Ahmed Alsaeed; Shalaby, Mennatallah Hatem; El-Kinawy, Nihal Saad; Elamawy, Alaa Adel; Abd El-Ghany, Shereen Mohamed

2017-07-01

Many risk factors may contribute to renal disease in patients with hemophilia A. We aimed to evaluate functional and structural renal abnormalities among a group of Egyptian children with severe and moderate hemophilia A using technetium-99m diethylene triamine pentaacetic acid ( 99m Tc-DTPA) and technetium-99 m dimercaptusuccinic acid ( 99m Tc-DMSA) scan. We also aimed to determine the relation between these abnormalities and different risk factors and disease severity. Forty male patients, 16 with severe and 24 with moderate hemophilia A, were enrolled in this study. Their mean age was 10.2 ± 4.3 years (range, 5-17 years). Full history taking, clinical examination, laboratory, and radionuclide investigations including serum creatinine, blood urea nitrogen (BUN), urine analysis, creatinine clearance, 24-hour urinary protein, 99m Tc-DTPA scan, and 99m Tc-DMSA scan were performed to all enrolled patients. Serum creatinine and BUN were normal in all patients, and corrected creatinine clearance was diminished in 2 patients. However, 99m Tc-DTPA results yielded 19 (47.5%) patients with diminished glomerular filtration rate (GFR). Moreover, it showed that 14 (35%) had obstructive uropathy, 15 (37.5%) had obstructive nephropathy, while 11 (27.5%) patients showed normal scan. One patient had atrophy of 1 kidney on 99m Tc-DMSA scan. Among our cohort, 5 (12.5%) patients were hypertensive. Microscopic hematuria was detected in 14 (35%) patients while 72.5% had proteinuria. We found an association between hematuria and hypertension with diminished GFR. Despite normal kidney functions (serum creatinine and BUN), we found a high rate of diminished GFR and obstructive uropathy and nephropathy as detected by 99m Tc-DTPA scan among children with hemophilia A.

High-throughput machining using a high-average power ultrashort pulse laser and high-speed polygon scanner

NASA Astrophysics Data System (ADS)

Schille, Joerg; Schneider, Lutz; Streek, André; Kloetzer, Sascha; Loeschner, Udo

2016-09-01

High-throughput ultrashort pulse laser machining is investigated on various industrial grade metals (aluminum, copper, and stainless steel) and Al2O3 ceramic at unprecedented processing speeds. This is achieved by using a high-average power picosecond laser in conjunction with a unique, in-house developed polygon mirror-based biaxial scanning system. Therefore, different concepts of polygon scanners are engineered and tested to find the best architecture for high-speed and precision laser beam scanning. In order to identify the optimum conditions for efficient processing when using high-average laser powers, the depths of cavities made in the samples by varying the processing parameter settings are analyzed and, from the results obtained, the characteristic removal values are specified. For overlapping pulses of optimum fluence, the removal rate is as high as 27.8 mm3/min for aluminum, 21.4 mm3/min for copper, 15.3 mm3/min for stainless steel, and 129.1 mm3/min for Al2O3, when a laser beam of 187 W average laser powers irradiates. On stainless steel, it is demonstrated that the removal rate increases to 23.3 mm3/min when the laser beam is very fast moving. This is thanks to the low pulse overlap as achieved with 800 m/s beam deflection speed; thus, laser beam shielding can be avoided even when irradiating high-repetitive 20-MHz pulses.

Bone diseases in rabbits with hyperparathyroidism: computed tomography, magnetic resonance imaging and histopathology.

PubMed

Bai, Rong-jie; Cong, De-gang; Shen, Bao-zhong; Han, Ming-jun; Wu, Zhen-hua

2006-08-05

Hyperparathyroidism (HPT) occurs at an early age and has a high disability rate. Unfortunately, confirmed diagnosis in most patients is done at a very late stage, when the patients have shown typical symptoms and signs, and when treatment does not produce any desirable effect. It has become urgent to find a method that would detect early bone diseases in HPT to obtain time for the ideal treatment. This study evaluated the accuracy of high field magnetic resonance imaging (MRI) combined with spiral computed tomography (SCT) scan in detecting early bone diseases in HPT, through imaging techniques and histopathological examinations on an animal model of HPT. Eighty adult rabbits were randomly divided into two groups with forty in each. The control group was fed normal diet (Ca:P = 1:0.7); the experimental group was fed high phosphate diet (Ca:P = 1:7) for 3, 4, 5, or 6-month intervals to establish the animal model of HPT. The staging and imaging findings of the early bone diseases in HPT were determined by high field MRI and SCT scan at the 3rd, 4th, 5th and 6th month. Each rabbit was sacrificed after high field MRI and SCT scan, and the parathyroid and bones were removed for pathological examination to evaluate the accuracy of imaging diagnosis. Parathyroid histopathological studies revealed hyperplasia, osteoporosis and early cortical bone resorption. The bone diseases in HPT displayed different levels of low signal intensity on T(1)WI and low to intermediate signal intensity on T(2)WI in bone of stage 0, I, II or III, but showed correspondingly absent, probable, osteoporotic and subperiosteal cortical resorption on SCT scan. High field MRI combined with SCT scan not only detects early bone diseases in HPT, but also indicates staging, and might be a reliable method of studying early bone diseases in HPT.

ON-SITE SOLID-PHASE EXTRACTION AND LABORATORY ...

EPA Pesticide Factsheets

Fragrance materials such as synthetic musks in aqueous samples, are normally determined by gas chromatography/mass spectrometry in the selected ion monitoring (SIM) mode to provide maximum sensitivity after liquid-liquid extraction of I -L samples. Full-scan mass spectra are required to verify that a target analyte has been found by comparison with the mass spectra of fragrance compounds in the NIST mass spectral library. A I -L sample usually provides insufficient analyte for full scan data acquisition. This paper describes an on-site extraction method developed at the U.S. Environmental Protection Agency (USEPA)- Las Vegas Nevada - for synthetic musks from 60 L of wastewater effluent. Such a large sample volume permits high-quality, full-scan mass spectra to be obtained for a wide array of synthetic musks. Quantification of these compounds was achieved from the full-scan data directly, without the need to acquire SIM data. The detection limits obtained with this method are an order of magnitude lower than those obtained from liquid-liquid and other solid phase extraction methods. This method is highly reproducible, and recoveries ranged from 80 to 97% in spiked sewage treatment plant effluent. The high rate of sorbent-sample mass transfer eliminated the need for a methanolic activation step, which reduced extraction time, labor, and solvent use, More samples could be extracted in the field at lower cost. After swnple extraction, the light- weight cartridges ar

[Molecular beacon based PNA-FISH method combined with fluorescence scanning for rapid detection of Listeria monocytogenes].

PubMed

Wu, Shan; Zhang, Xiaofeng; Shuai, Jiangbing; Li, Ke; Yu, Huizhen; Jin, Chenchen

2016-07-04

To simplify the PNA-FISH (Peptide nucleic acid-fluorescence in situ hybridization) test, molecular beacon based PNA probe combined with fluorescence scanning detection technology was applied to replace the original microscope observation to detect Listeria monocytogenes The 5′ end and 3′ end of the L. monocytogenes specific PNA probes were labeled with the fluorescent group and the quenching group respectively, to form a molecular beacon based PNA probe. When PNA probe used for fluorescence scanning and N1 treatment as the control, the false positive rate was 11.4%, and the false negative rate was 0; when N2 treatment as the control, the false positive rate decreased to 4.3%, but the false negative rate rose to 18.6%. When beacon based PNA probe used for fluorescence scanning, taken N1 treatment as blank control, the false positive rate was 8.6%, and the false negative rate was 1.4%; taken N2 treatment as blank control, the false positive rate was 5.7%, and the false negative rate was 1.4%. Compared with PNA probe, molecular beacon based PNA probe can effectively reduce false positives and false negatives. The success rates of hybridization of the two PNA probes were 83.3% and 95.2% respectively; and the rates of the two beacon based PNA probes were 91.7% and 90.5% respectively, which indicated that labeling the both ends of the PNA probe dose not decrease the hybridization rate with the target bacteria. The combination of liquid phase PNA-FISH and fluorescence scanning method, can significantly improve the detection efficiency.

High-bandwidth scanned-wavelength-modulation spectroscopy sensors for temperature and H2O in a rotating detonation engine

NASA Astrophysics Data System (ADS)

Goldenstein, Christopher S.; Almodóvar, Christopher A.; Jeffries, Jay B.; Hanson, Ronald K.; Brophy, Christopher M.

2014-10-01

The design and use of two-color tunable diode laser (TDL) absorption sensors for measurements of temperature and H2O in a rotating detonation engine (RDE) are presented. Both sensors used first-harmonic-normalized scanned-wavelength-modulation spectroscopy with second-harmonic detection (scanned-WMS-2f/1f) to account for non-absorbing transmission losses and emission encountered in the harsh combustion environment. One sensor used two near-infrared (NIR) TDLs near 1391.7 nm and 1469.3 nm that were modulated at 225 kHz and 285 kHz, respectively, and sinusoidally scanned across the peak of their respective H2O absorption transitions to provide a measurement rate of 50 kHz and a detection limit in the RDE of 0.2% H2O by mole. The other sensor used two mid-infrared (MIR) TDLs near 2551 nm and 2482 nm that were modulated at 90 kHz and 112 kHz, respectively, and sinusoidally scanned across the peak of their respective H2O transitions to provide a measurement rate of 10 kHz and a detection limit in the RDE of 0.02% H2O by mole. Four H2O absorption transitions with different lower-state energies were used to assess the homogeneity of temperature in the measurement plane. Experimentally derived spectroscopic parameters that enable temperature and H2O sensing to within 1.5-3.5% of known values are reported. The sensor design enabling the high-bandwidth scanned-WMS-2f/1f measurements is presented. The two sensors were deployed across two orthogonal and coplanar lines-of-sight (LOS) located in the throat of a converging-diverging nozzle at the RDE combustor exit. Measurements in the non-premixed H2-fueled RDE indicate that the temperature and H2O oscillate at the detonation frequency (≈3.25 kHz) and that production of H2O is a weak function of global equivalence ratio.

Influence of the laser pulse repetition rate and scanning speed on the morphology of Ag nanostructures fabricated by pulsed laser ablation of solid target in water

NASA Astrophysics Data System (ADS)

Nikolov, A. S.; Balchev, I. I.; Nedyalkov, N. N.; Kostadinov, I. K.; Karashanova, D. B.; Atanasova, G. B.

2017-11-01

Nanostructures of noble metal were produced by pulsed laser ablation in liquid. A solid Ag target was immersed in double distilled water and a CuBr laser in a master oscillator—power amplifier configuration oscillating at 511 nm and emitting pulses with duration of 30 ns at a repetition rate of up to 20 kHz was employed to produce different colloids. The impact was studied of the laser pulse repetition rate and the beam scanning speed on the morphology of the nanostructures formed. Further, the optical extinction spectra of the colloids in the UV/VIS range were measured and used to make an indirect assessment of the changes in the shape and size distribution of the nanostructures. The transmission values in the near UV range were used to estimate the efficiency of the ablation process under the different experimental conditions implemented. A visualization of the nanostructures was made possible by transmission electron microscopy (TEM). The structure and phase composition of the nanoparticles were studied by high-resolution transmission electron microscopy (HRTEM) and selected area electron diffraction (SAED), while the alteration of the target surface caused by the impact of the high-repetition-rate laser illumination was investigated by X-ray photoelectron spectroscopy (XPS). The optimal conditions were determined yielding the highest efficiency in terms of amount of ablated material.

Use of rapid-scan EPR to improve detection sensitivity for spin-trapped radicals.

PubMed

Mitchell, Deborah G; Rosen, Gerald M; Tseitlin, Mark; Symmes, Breanna; Eaton, Sandra S; Eaton, Gareth R

2013-07-16

The short lifetime of superoxide and the low rates of formation expected in vivo make detection by standard continuous wave (CW) electron paramagnetic resonance (EPR) challenging. The new rapid-scan EPR method offers improved sensitivity for these types of samples. In rapid-scan EPR, the magnetic field is scanned through resonance in a time that is short relative to electron spin relaxation times, and data are processed to obtain the absorption spectrum. To validate the application of rapid-scan EPR to spin trapping, superoxide was generated by the reaction of xanthine oxidase and hypoxanthine with rates of 0.1-6.0 μM/min and trapped with 5-tert-butoxycarbonyl-5-methyl-1-pyrroline-N-oxide (BMPO). Spin trapping with BMPO to form the BMPO-OOH adduct converts the very short-lived superoxide radical into a more stable spin adduct. There is good agreement between the hyperfine splitting parameters obtained for BMPO-OOH by CW and rapid-scan EPR. For the same signal acquisition time, the signal/noise ratio is >40 times higher for rapid-scan than for CW EPR. Rapid-scan EPR can detect superoxide produced by Enterococcus faecalis at rates that are too low for detection by CW EPR. Copyright © 2013 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Handheld ultrahigh speed swept source optical coherence tomography instrument using a MEMS scanning mirror.

PubMed

Lu, Chen D; Kraus, Martin F; Potsaid, Benjamin; Liu, Jonathan J; Choi, Woojhon; Jayaraman, Vijaysekhar; Cable, Alex E; Hornegger, Joachim; Duker, Jay S; Fujimoto, James G

2013-12-20

We developed an ultrahigh speed, handheld swept source optical coherence tomography (SS-OCT) ophthalmic instrument using a 2D MEMS mirror. A vertical cavity surface-emitting laser (VCSEL) operating at 1060 nm center wavelength yielded a 350 kHz axial scan rate and 10 µm axial resolution in tissue. The long coherence length of the VCSEL enabled a 3.08 mm imaging range with minimal sensitivity roll-off in tissue. Two different designs with identical optical components were tested to evaluate handheld OCT ergonomics. An iris camera aided in alignment of the OCT beam through the pupil and a manual fixation light selected the imaging region on the retina. Volumetric and high definition scans were obtained from 5 undilated normal subjects. Volumetric OCT data was acquired by scanning the 2.4 mm diameter 2D MEMS mirror sinusoidally in the fast direction and linearly in the orthogonal slow direction. A second volumetric sinusoidal scan was obtained in the orthogonal direction and the two volumes were processed with a software algorithm to generate a merged motion-corrected volume. Motion-corrected standard 6 x 6 mm(2) and wide field 10 x 10 mm(2) volumetric OCT data were generated using two volumetric scans, each obtained in 1.4 seconds. High definition 10 mm and 6 mm B-scans were obtained by averaging and registering 25 B-scans obtained over the same position in 0.57 seconds. One of the advantages of volumetric OCT data is the generation of en face OCT images with arbitrary cross sectional B-scans registered to fundus features. This technology should enable screening applications to identify early retinal disease, before irreversible vision impairment or loss occurs. Handheld OCT technology also promises to enable applications in a wide range of settings outside of the traditional ophthalmology or optometry clinics including pediatrics, intraoperative, primary care, developing countries, and military medicine.

Directed Biosynthesis of Oriented Crystalline Cellulose for Advanced Composite Fibers

DTIC Science & Technology

2012-05-03

8 growth rate Table 2. An optimized minimal salts high conductivity growth medium (named 9 Son-Matsuoka- Fructose , SMF) based on the optimized...basis for a high -conductivity medium for Acetobacter that also contained corn steep liquor. List of Figures Figure 1. Scanning electron micrographs of...bacterial cellulose production include corn steep liquor (Matsuoka et al., 1996) apples, beer wort (Brown, 1886; Herrmann, 1928), corn syrup , kale (black

Video-rate volumetric functional imaging of the brain at synaptic resolution.

PubMed

Lu, Rongwen; Sun, Wenzhi; Liang, Yajie; Kerlin, Aaron; Bierfeld, Jens; Seelig, Johannes D; Wilson, Daniel E; Scholl, Benjamin; Mohar, Boaz; Tanimoto, Masashi; Koyama, Minoru; Fitzpatrick, David; Orger, Michael B; Ji, Na

2017-04-01

Neurons and neural networks often extend hundreds of micrometers in three dimensions. Capturing the calcium transients associated with their activity requires volume imaging methods with subsecond temporal resolution. Such speed is a challenge for conventional two-photon laser-scanning microscopy, because it depends on serial focal scanning in 3D and indicators with limited brightness. Here we present an optical module that is easily integrated into standard two-photon laser-scanning microscopes to generate an axially elongated Bessel focus, which when scanned in 2D turns frame rate into volume rate. We demonstrated the power of this approach in enabling discoveries for neurobiology by imaging the calcium dynamics of volumes of neurons and synapses in fruit flies, zebrafish larvae, mice and ferrets in vivo. Calcium signals in objects as small as dendritic spines could be resolved at video rates, provided that the samples were sparsely labeled to limit overlap in their axially projected images.

Dosimetric characterization of a microDiamond detector in clinical scanned carbon ion beams.

PubMed

Marinelli, Marco; Prestopino, G; Verona, C; Verona-Rinati, G; Ciocca, M; Mirandola, A; Mairani, A; Raffaele, L; Magro, G

2015-04-01

To investigate for the first time the dosimetric properties of a new commercial synthetic diamond detector (PTW microDiamond) in high-energy scanned clinical carbon ion beams generated by a synchrotron at the CNAO facility. The detector response was evaluated in a water phantom with actively scanned carbon ion beams ranging from 115 to 380 MeV/u (30-250 mm Bragg peak depth in water). Homogeneous square fields of 3 × 3 and 6 × 6 cm(2) were used. Short- and medium-term (2 months) detector response stability, dependence on beam energy as well as ion type (carbon ions and protons), linearity with dose, and directional and dose-rate dependence were investigated. The depth dose curve of a 280 MeV/u carbon ion beam, scanned over a 3 × 3 cm(2) area, was measured with the microDiamond detector and compared to that measured using a PTW Advanced Markus ionization chamber, and also simulated using fluka Monte Carlo code. The detector response in two spread-out-Bragg-peaks (SOBPs), respectively, centered at 9 and 21 cm depths in water and calculated using the treatment planning system (TPS) used at CNAO, was measured. A negligible drift of detector sensitivity within the experimental session was seen, indicating that no detector preirradiation was needed. Short-term response reproducibility around 1% (1 standard deviation) was found. Only 2% maximum variation of microDiamond sensitivity was observed among all the evaluated proton and carbon ion beam energies. The detector response showed a good linear behavior. Detector sensitivity was found to be dose-rate independent, with a variation below 1.3% in the evaluated dose-rate range. A very good agreement between measured and simulated Bragg curves with both microDiamond and Advanced Markus chamber was found, showing a negligible LET dependence of the tested detector. A depth dose curve was also measured by positioning the microDiamond with its main axis oriented orthogonally to the beam direction. A strong distortion in Bragg peak measurement was observed, confirming manufacturer recommendation on avoiding such configuration. Very good results were obtained for SOBP measurements, with a difference below 1% between measured and TPS-calculated doses. The stability of detector sensitivity in the observation period was within the experimental uncertainty. Dosimetric characterization of a PTW microDiamond detector in high-energy scanned carbon ion beams was performed. The results of the present study showed that this detector is suitable for dosimetry of clinical carbon ion beams, with a negligible LET and dose-rate dependence.

Microstructural Characteristics of High Rate Plastic Deformation in Elektron™ WE43 Magnesium Alloy

NASA Astrophysics Data System (ADS)

Hamilton, Joseph; Brennan, Sarah T.; Sohn, Yongho; Davis, Bruce; DeLorme, Rick; Cho, Kyu

High strain rate deformation of WE43 magnesium alloy was carried out by high velocity impacts, and the characteristics and mechanisms of microstructural damage were examined. Six samples were subjected to a variety of high velocity impact loadings that resulted in both partial and full damage. Optical, scanning and transmission electron microscopy analyses were performed in order to identify regions of shear localization. These regions were used to map, both quantitatively and qualitatively, the effects of deformation on the microstructure. Shear localization was observed in every sample, and its depth was measured. Evidence of shear localization was observed to a greater extent in samples with partial damage while fracturing was observed more frequently in samples with full damage.

Acute effects of a guided relaxation routine (body scan) on tobacco withdrawal symptoms and cravings in abstinent smokers.

PubMed

Cropley, Mark; Ussher, Michael; Charitou, Elli

2007-06-01

To examine the acute effects of a guided relaxation routine (body scan) on desire to smoke and tobacco withdrawal symptoms in overnight abstinent smokers. Experimental. Thirty individuals reporting to smoke 10 or more cigarettes daily for at least 3 years. Participants were assigned randomly to complete a 10-minute body scan (experimental group n = 15) or listen to a natural history passage for 10 minutes (control group n = 15). Ratings of strength of desire to smoke and smoking withdrawal symptoms were assessed at baseline, immediately after the interventions, and 5, 10 and 15 minutes post-intervention. There was a significant group x time interaction for strength of desire to smoke. The mean desire to smoke rating was significantly lower in the body scan group relative to the control group immediately after the intervention, and 5 minutes post-intervention. The body scan group also reported lower ratings of irritability, tension and restlessness, relative to the controls. A brief body scan intervention reduces strength of desire to smoke and some tobacco withdrawal symptoms in temporarily abstaining smokers. The body scan may be beneficial as a technique for managing cigarette cravings and withdrawal.

Spatial bedrock erosion distribution in a natural gorge

NASA Astrophysics Data System (ADS)

Beer, A. R.; Turowski, J. M.; Kirchner, J. W.

2015-12-01

Quantitative analysis of morphological evolution both in terrestrial and planetary landscapes is of increasing interest in the geosciences. In mountainous regions, bedrock channel formation as a consequence of the interaction of uplift and erosion processes is fundamental for the entire surface evolution. Hence, the accurate description of bedrock channel development is important for landscape modelling. To verify existing concepts developed in the lab and to analyse how in situ channel erosion rates depend on the interrelations of discharge, sediment transport and topography, there is a need of highly resolved topographic field data. We analyse bedrock erosion over two years in a bedrock gorge downstream of the Gorner glacier above the town of Zermatt, Switzerland. At the study site, the Gornera stream cuts through a roche moutonnée in serpentine rock of 25m length, 5m width and 8m depth. We surveyed bedrock erosion rates using repeat terrestrial laser scanning (TLS) with an average point spacing of 5mm. Bedrock erosion rates in direction of the individual surface normals were studied directly on the scanned point clouds applying the M3C2 algorithm (Lague et al., 2013, ISPRS). The surveyed erosion patterns were compared to a simple stream erosivity visualisation obtained from painted bedrock sections at the study location. Spatially distributed erosion rates on bedrock surfaces based on millions of scan points allow deduction of millimeter-scale mean annual values of lateral erosion, incision and downstream erosion on protruding streambed surfaces. The erosion rate on a specific surface point is shown to depend on the position of this surface point in the channel's cross section, its height above the streambed and its spatial orientation to the streamflow. Abrasion by impacting bedload was likely the spatially dominant erosion process, as confirmed by the observed patterns along the painted bedrock sections. However, a single plucking event accounted for the half of the total eroded material. Our results demonstrate the practicability of TLS for highly resolved spatio-temporal erosion monitoring in the field and quantitatively confirm concepts of spatially varying erosion rates based current thinking. Furthermore, we introduce an easy-to-apply method for qualitative spatial erosion detection by paint.

Morphological Changes Along a Dike Landside Slope Sampled by 4d High Resolution Terrestrial Laser Scanning

NASA Astrophysics Data System (ADS)

Herrero-Huertaa, Mónica; Lindenbergh, Roderik; Ponsioen, Luc; van Damme, Myron

2016-06-01

Emergence of light detection and ranging (LiDAR) technology provides new tools for geomorphologic studies improving spatial and temporal resolution of data sampling hydrogeological instability phenomena. Specifically, terrestrial laser scanning (TLS) collects high resolution 3D point clouds allowing more accurate monitoring of erosion rates and processes, and thus, quantify the geomorphologic change on vertical landforms like dike landside slopes. Even so, TLS captures observations rapidly and automatically but unselectively. In this research, we demonstrate the potential of TLS for morphological change detection, profile creation and time series analysis in an emergency simulation for characterizing and monitoring slope movements in a dike. The experiment was performed near Schellebelle (Belgium) in November 2015, using a Leica Scan Station C10. Wave overtopping and overflow over a dike were simulated whereby the loading conditions were incrementally increased and 14 successful scans were performed. The aim of the present study is to analyse short-term morphological dynamic processes and the spatial distribution of erosion and deposition areas along a dike landside slope. As a result, we are able to quantify the eroded material coming from the impact on the terrain induced by wave overtopping which caused the dike failure in a few minutes in normal storm scenarios (Q = 25 l/s/m) as 1.24 m3. As this shows that the amount of erosion is measurable using close range techniques; the amount and rate of erosion could be monitored to predict dike collapse in emergency situation. The results confirm the feasibility of the proposed methodology, providing scalability to a comprehensive analysis over a large extension of a dike (tens of meters).

Evaluation of dead-time corrections for post-radionuclide-therapy (177)Lu quantitative imaging with low-energy high-resolution collimators.

PubMed

Celler, Anna; Piwowarska-Bilska, Hanna; Shcherbinin, Sergey; Uribe, Carlos; Mikolajczak, Renata; Birkenfeld, Bozena

2014-01-01

Dead-time (DT) effects rarely cause problems in diagnostic single-photon emission computed tomography (SPECT) studies; however, in post-radionuclide-therapy imaging, DT can be substantial. Therefore, corrections may be necessary if quantitative images are used in image-based dosimetry or for evaluation of therapy outcomes. This task is particularly challenging if low-energy collimators are used. Our goal was to design a simple method to determine the dead-time correction factor (DTCF) without the need for phantom experiments and complex calculations. Planar and SPECT/CT scans of a water phantom containing a 70 ml bottle filled with lutetium-177 (Lu) were acquired over 60 days. Two small Lu markers were used in all scans. The DTCF based on the ratio of observed to true count rates measured over the entire spectrum and using photopeak primary photons only was estimated for phantom (DT present) and marker (no DT) scans. In addition, variations in counts in SPECT projections (potentially caused by varying bremsstrahlung and scatter) were investigated. For count rates that were about two-fold higher than typically seen in post-therapy Lu scans, the maximum DTCF reached a level of about 17%. The DTCF values determined directly from the phantom experiments using the total energy spectrum and photopeak counts only were equal to 13 and 16%, respectively. They were closely matched by those from the proposed marker-based method, which uses only two energy windows and measures photopeak primary photons (15-17%). A simple, marker-based method allowing for determination of the DTCF in high-activity Lu imaging studies has been proposed and validated using phantom experiments.

Low-Dose-Rate Computed Tomography System Utilizing 25 mm/s-Scan Silicon X-ray Diode and Its Application to Iodine K-Edge Imaging Using Filtered Bremsstrahlung Photons

NASA Astrophysics Data System (ADS)

Matsushita, Ryo; Sato, Eiichi; Yanbe, Yutaka; Chiba, Hiraku; Maeda, Tomoko; Hagiwara, Osahiko; Matsukiyo, Hiroshi; Osawa, Akihiro; Enomoto, Toshiyuki; Watanabe, Manabu; Kusachi, Shinya; Sato, Shigehiro; Ogawa, Akira; Onagawa, Jun

2013-03-01

A low-dose-rate X-ray computed tomography (CT) system is useful for reducing absorbed dose for patients. The CT system with a tube current of sub-mA was developed using a silicon X-ray diode (Si-XD). The Si-XD is a high-sensitivity Si photodiode (PD) selected for detecting X-ray photons, and the X-ray sensitivity of the Si-XD was twice as high as that of Si-PD cerium-doped yttrium aluminum perovskite [YAP(Ce)]. X-ray photons are directly detected using the Si-XD without a scintillator, and the photocurrent from the diode is amplified using current-voltage and voltage-voltage amplifiers. The output voltage is converted into logical pulses using a voltage-frequency converter with a maximum frequency of 500 kHz, and the frequency is proportional to the voltage. The pulses from the converter are sent to the differentiator with a time constant of 500 ns to generate short positive pulses for counting, and the pulses are counted using a counter card. Tomography is accomplished by repeated linear scans and rotations of an object, and projection curves of the object are obtained by the linear scan. The exposure time for obtaining a tomogram was 5 min at a scan step of 0.5 mm and a rotation step of 3.0°. The tube current and voltage were 0.55 mA and 60 kV, respectively, and iodine K-edge CT was carried out using filtered bremsstrahlung X-ray spectra with a peak energy of 38 keV.

A scanning PIV method for fine-scale turbulence measurements

NASA Astrophysics Data System (ADS)

Lawson, John M.; Dawson, James R.

2014-12-01

A hybrid technique is presented that combines scanning PIV with tomographic reconstruction to make spatially and temporally resolved measurements of the fine-scale motions in turbulent flows. The technique uses one or two high-speed cameras to record particle images as a laser sheet is rapidly traversed across a measurement volume. This is combined with a fast method for tomographic reconstruction of the particle field for use in conjunction with PIV cross-correlation. The method was tested numerically using DNS data and with experiments in a large mixing tank that produces axisymmetric homogeneous turbulence at . A parametric investigation identifies the important parameters for a scanning PIV set-up and provides guidance to the interested experimentalist in achieving the best accuracy. Optimal sheet spacings and thicknesses are reported, and it was found that accurate results could be obtained at quite low scanning speeds. The two-camera method is the most robust to noise, permitting accurate measurements of the velocity gradients and direct determination of the dissipation rate.

Geographic clusters in underimmunization and vaccine refusal.

PubMed

Lieu, Tracy A; Ray, G Thomas; Klein, Nicola P; Chung, Cindy; Kulldorff, Martin

2015-02-01

Parental refusal and delay of childhood vaccines has increased in recent years and is believed to cluster in some communities. Such clusters could pose public health risks and barriers to achieving immunization quality benchmarks. Our aims were to (1) describe geographic clusters of underimmunization and vaccine refusal, (2) compare clusters of underimmunization with different vaccines, and (3) evaluate whether vaccine refusal clusters may pose barriers to achieving high immunization rates. We analyzed electronic health records among children born between 2000 and 2011 with membership in Kaiser Permanente Northern California. The study population included 154,424 children in 13 counties with continuous membership from birth to 36 months of age. We used spatial scan statistics to identify clusters of underimmunization (having missed 1 or more vaccines by 36 months of age) and vaccine refusal (based on International Classification of Diseases, Ninth Revision, Clinical Modification codes). We identified 5 statistically significant clusters of underimmunization among children who turned 36 months old during 2010-2012. The underimmunization rate within clusters ranged from 18% to 23%, and the rate outside them was 11%. Children in the most statistically significant cluster had 1.58 (P < .001) times the rate of underimmunization as others. Underimmunization with measles, mumps, rubella vaccine and varicella vaccines clustered in similar geographic areas. Vaccine refusal also clustered, with rates of 5.5% to 13.5% within clusters, compared with 2.6% outside them. Underimmunization and vaccine refusal cluster geographically. Spatial scan statistics may be a useful tool to identify locations with challenges to achieving high immunization rates, which deserve focused intervention. Copyright © 2015 by the American Academy of Pediatrics.

Sunspot drawings handwritten character recognition method based on deep learning

NASA Astrophysics Data System (ADS)

Zheng, Sheng; Zeng, Xiangyun; Lin, Ganghua; Zhao, Cui; Feng, Yongli; Tao, Jinping; Zhu, Daoyuan; Xiong, Li

2016-05-01

High accuracy scanned sunspot drawings handwritten characters recognition is an issue of critical importance to analyze sunspots movement and store them in the database. This paper presents a robust deep learning method for scanned sunspot drawings handwritten characters recognition. The convolution neural network (CNN) is one algorithm of deep learning which is truly successful in training of multi-layer network structure. CNN is used to train recognition model of handwritten character images which are extracted from the original sunspot drawings. We demonstrate the advantages of the proposed method on sunspot drawings provided by Chinese Academy Yunnan Observatory and obtain the daily full-disc sunspot numbers and sunspot areas from the sunspot drawings. The experimental results show that the proposed method achieves a high recognition accurate rate.

In-Line Wear Monitor

DTIC Science & Technology

1988-09-01

and is available for future use in designs with the power supply in the sensor if needed. 4.1 PREAMPLIFIER Two different preamplifier designs were high...30. Sensaor mounting orientetisms for vibratiom tests. 34 A 1/2 g sinewave scan was performed up to 3 kHz at a fairly slow rate (1 oc- tave/minute

Hydrothermal synthesis of nanostructured graphene/polyaniline composites as high-capacitance electrode materials for supercapacitors

PubMed Central

Wang, Ronghua; Han, Meng; Zhao, Qiannan; Ren, Zonglin; Guo, Xiaolong; Xu, Chaohe; Hu, Ning; Lu, Li

2017-01-01

As known to all, hydrothermal synthesis is a powerful technique for preparing inorganic and organic materials or composites with different architectures. In this reports, by controlling hydrothermal conditions, nanostructured polyaniline (PANi) in different morphologies were composited with graphene sheets (GNS) and used as electrode materials of supercapacitors. Specifically, ultrathin PANi layers with total thickness of 10–20 nm are uniformly composited with GNS by a two-step hydrothermal-assistant chemical oxidation polymerization process; while PANi nanofibers with diameter of 50~100 nm are obtained by a one-step direct hydrothermal process. Benefitting from the ultrathin layer and porous structure, the sheet-like GNS/PANi composites can deliver specific capacitances of 532.3 to 304.9 F/g at scan rates of 2 to 50 mV/s. And also, this active material showed very good stability with capacitance retention as high as ~99.6% at scan rate of 50 mV/s, indicating a great potential for using in supercapacitors. Furthermore, the effects of hydrothermal temperatures on the electrochemical performances were systematically studied and discussed. PMID:28291246

Scanning SQUID microscopy of a ferromanganese crust from the northwestern Pacific: Submillimeter scale magnetostratigraphy as a new tool for age determination and mapping of environmental magnetic parameters

NASA Astrophysics Data System (ADS)

Noguchi, A.; Oda, H.; Yamamoto, Y.; Usui, A.; Sato, M.; Kawai, J.

2017-06-01

Ferromanganese crusts record long-term deep-sea environmental changes. Thus, providing their reliable high-resolution age models is important. We applied a magnetostratigraphic technique to estimate the growth rate of a ferromanganese crust using scanning SQUID (superconducting quantum interference device) microscope (SSM). SSM is designed to map the magnetic field across thin sections with submillimeter resolution. The crust sample was taken from the Takuyo-Daigo Seamount, northwestern Pacific, and recorded a limited supply of dust and sediment from continents. After drift correction and removal of spike noises, the magnetic field values were stacked within the areas of high signal-to-noise ratios. By correlating the obtained profiles with a standard geomagnetic polarity timescale, we obtained an average growth rate of 3.37 ± 0.06 mm/Ma, which is consistent with that obtained by 10Be/9Be geochronology (2.93 ± 0.15 mm/Ma). S ratio mapping shows low values after 3 Ma, associated with voids between columnar structures.

Video-rate functional photoacoustic microscopy at depths

NASA Astrophysics Data System (ADS)

Wang, Lidai; Maslov, Konstantin; Xing, Wenxin; Garcia-Uribe, Alejandro; Wang, Lihong V.

2012-10-01

We report the development of functional photoacoustic microscopy capable of video-rate high-resolution in vivo imaging in deep tissue. A lightweight photoacoustic probe is made of a single-element broadband ultrasound transducer, a compact photoacoustic beam combiner, and a bright-field light delivery system. Focused broadband ultrasound detection provides a 44-μm lateral resolution and a 28-μm axial resolution based on the envelope (a 15-μm axial resolution based on the raw RF signal). Due to the efficient bright-field light delivery, the system can image as deep as 4.8 mm in vivo using low excitation pulse energy (28 μJ per pulse, 0.35 mJ/cm2 on the skin surface). The photoacoustic probe is mounted on a fast-scanning voice-coil scanner to acquire 40 two-dimensional (2-D) B-scan images per second over a 9-mm range. High-resolution anatomical imaging is demonstrated in the mouse ear and brain. Via fast dual-wavelength switching, oxygen dynamics of mouse cardio-vasculature is imaged in realtime as well.

Mechanism of high growth rate for diamond-like carbon films synthesized by helicon wave plasma chemical vapor deposition

NASA Astrophysics Data System (ADS)

Peiyu, JI; Jun, YU; Tianyuan, HUANG; Chenggang, JIN; Yan, YANG; Lanjian, ZHUGE; Xuemei, WU

2018-02-01

A high growth rate fabrication of diamond-like carbon (DLC) films at room temperature was achieved by helicon wave plasma chemical vapor deposition (HWP-CVD) using Ar/CH4 gas mixtures. The microstructure and morphology of the films were characterized by Raman spectroscopy and scanning electron microscopy. The diagnosis of plasma excited by a helicon wave was measured by optical emission spectroscopy and a Langmuir probe. The mechanism of high growth rate fabrication for DLC films by HWP-CVD has been discussed. The growth rate of the DLC films reaches a maximum value of 54 μm h-1 at the CH4 flow rate of 85 sccm, which is attributed to the higher plasma density during the helicon wave plasma discharge. The CH and H α radicals play an important role in the growth of DLC films. The results show that the H α radicals are beneficial to the formation and stabilization of C=C bond from sp2 to sp3.

Multiplexed data independent acquisition (MSX-DIA) applied by high resolution mass spectrometry improves quantification quality for the analysis of histone peptides

PubMed Central

Sidoli, Simone; Fujiwara, Rina; Garcia, Benjamin A.

2016-01-01

We present the mass spectrometry (MS) based application of the innovative, although scarcely exploited, multiplexed data-independent acquisition (MSX-DIA) for the analysis of histone post-translational modifications (PTMs). Histones are golden standard for complexity in MS based proteomics, due to their large number of combinatorial modifications, leading to isobaric peptides after proteolytic digestion. DIA has thus gained popularity for the purpose as it allows for MS/MS-based quantification without upfront assay development. In this work, we evaluated the performance of traditional DIA versus MSX-DIA in terms of MS/MS spectra quality, instrument scan rate and quantification precision using histones from HeLa cells. We used an MS/MS isolation window of 10 and 6 m/z for DIA and MSX-DIA, respectively. Four MS/MS scans were multiplexed for MSX-DIA. Despite MSX-DIA was programmed to perform 2-fold more MS/MS events than traditional DIA, it acquired on average ~5% more full MS scans, indicating even faster scan rate. Results highlighted an overall decrease of background ion signals using MSX-DIA, and we illustrated specific examples where peptides of different precursor masses were co-fragmented by DIA but not MSX-DIA. Taken together, MSX-DIA proved thus to be a more favorable method for histone analysis in data independent mode. PMID:27193262

A study on the use of Gumbel approximation with the Bernoulli spatial scan statistic.

PubMed

Read, S; Bath, P A; Willett, P; Maheswaran, R

2013-08-30

The Bernoulli version of the spatial scan statistic is a well established method of detecting localised spatial clusters in binary labelled point data, a typical application being the epidemiological case-control study. A recent study suggests the inferential accuracy of several versions of the spatial scan statistic (principally the Poisson version) can be improved, at little computational cost, by using the Gumbel distribution, a method now available in SaTScan(TM) (www.satscan.org). We study in detail the effect of this technique when applied to the Bernoulli version and demonstrate that it is highly effective, albeit with some increase in false alarm rates at certain significance thresholds. We explain how this increase is due to the discrete nature of the Bernoulli spatial scan statistic and demonstrate that it can affect even small p-values. Despite this, we argue that the Gumbel method is actually preferable for very small p-values. Furthermore, we extend previous research by running benchmark trials on 12 000 synthetic datasets, thus demonstrating that the overall detection capability of the Bernoulli version (i.e. ratio of power to false alarm rate) is not noticeably affected by the use of the Gumbel method. We also provide an example application of the Gumbel method using data on hospital admissions for chronic obstructive pulmonary disease. Copyright © 2013 John Wiley & Sons, Ltd.

Multiplexed data independent acquisition (MSX-DIA) applied by high resolution mass spectrometry improves quantification quality for the analysis of histone peptides.

PubMed

Sidoli, Simone; Fujiwara, Rina; Garcia, Benjamin A

2016-08-01

We present the MS-based application of the innovative, although scarcely exploited, multiplexed data-independent acquisition (MSX-DIA) for the analysis of histone PTMs. Histones are golden standard for complexity in MS based proteomics, due to their large number of combinatorial modifications, leading to isobaric peptides after proteolytic digestion. DIA has, thus, gained popularity for the purpose as it allows for MS/MS-based quantification without upfront assay development. In this work, we evaluated the performance of traditional DIA versus MSX-DIA in terms of MS/MS spectra quality, instrument scan rate and quantification precision using histones from HeLa cells. We used an MS/MS isolation window of 10 and 6 m/z for DIA and MSX-DIA, respectively. Four MS/MS scans were multiplexed for MSX-DIA. Despite MSX-DIA was programmed to perform two-fold more MS/MS events than traditional DIA, it acquired on average ∼5% more full MS scans, indicating even faster scan rate. Results highlighted an overall decrease of background ion signals using MSX-DIA, and we illustrated specific examples where peptides of different precursor masses were co-fragmented by DIA but not MSX-DIA. Taken together, MSX-DIA proved thus to be a more favorable method for histone analysis in data independent mode. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

C-FSCV: Compressive Fast-Scan Cyclic Voltammetry for Brain Dopamine Recording.

PubMed

Zamani, Hossein; Bahrami, Hamid Reza; Chalwadi, Preeti; Garris, Paul A; Mohseni, Pedram

2018-01-01

This paper presents a novel compressive sensing framework for recording brain dopamine levels with fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode. Termed compressive FSCV (C-FSCV), this approach compressively samples the measured total current in each FSCV scan and performs basic FSCV processing steps, e.g., background current averaging and subtraction, directly with compressed measurements. The resulting background-subtracted faradaic currents, which are shown to have a block-sparse representation in the discrete cosine transform domain, are next reconstructed from their compressively sampled counterparts with the block sparse Bayesian learning algorithm. Using a previously recorded dopamine dataset, consisting of electrically evoked signals recorded in the dorsal striatum of an anesthetized rat, the C-FSCV framework is shown to be efficacious in compressing and reconstructing brain dopamine dynamics and associated voltammograms with high fidelity (correlation coefficient, ), while achieving compression ratio, CR, values as high as ~ 5. Moreover, using another set of dopamine data recorded 5 minutes after administration of amphetamine (AMPH) to an ambulatory rat, C-FSCV once again compresses (CR = 5) and reconstructs the temporal pattern of dopamine release with high fidelity ( ), leading to a true-positive rate of 96.4% in detecting AMPH-induced dopamine transients.

Automated Facial Recognition of Computed Tomography-Derived Facial Images: Patient Privacy Implications.

PubMed

Parks, Connie L; Monson, Keith L

2017-04-01

The recognizability of facial images extracted from publically available medical scans raises patient privacy concerns. This study examined how accurately facial images extracted from computed tomography (CT) scans are objectively matched with corresponding photographs of the scanned individuals. The test subjects were 128 adult Americans ranging in age from 18 to 60 years, representing both sexes and three self-identified population (ancestral descent) groups (African, European, and Hispanic). Using facial recognition software, the 2D images of the extracted facial models were compared for matches against five differently sized photo galleries. Depending on the scanning protocol and gallery size, in 6-61 % of the cases, a correct life photo match for a CT-derived facial image was the top ranked image in the generated candidate lists, even when blind searching in excess of 100,000 images. In 31-91 % of the cases, a correct match was located within the top 50 images. Few significant differences (p > 0.05) in match rates were observed between the sexes or across the three age cohorts. Highly significant differences (p < 0.01) were, however, observed across the three ancestral cohorts and between the two CT scanning protocols. Results suggest that the probability of a match between a facial image extracted from a medical scan and a photograph of the individual is moderately high. The facial image data inherent in commonly employed medical imaging modalities may need to consider a potentially identifiable form of "comparable" facial imagery and protected as such under patient privacy legislation.

Simultaneous SLO/OCT imaging of the human retina with axial eye motion correction.

PubMed

Pircher, Michael; Baumann, Bernhard; Götzinger, Erich; Sattmann, Harald; Hitzenberger, Christoph K

2007-12-10

It has been shown that transversal scanning (or en-face) optical coherence tomography (TS-OCT) represents an imaging modality capable to record high isotropic resolution images of the human retina in vivo. However, axial eye motion still remains a challenging problem of this technique. In this paper we introduce a novel method to compensate for this eye motion. An auxiliary spectral domain partial coherence interferometer (SD-PCI) was integrated into an existing TS-OCT system and used to measure accurately the position of the cornea. A light source emitting at 1310nm was used in the additional interferometer which enabled a nearly loss free coupling of the two measurement beams via a dichroic mirror. The recorded corneal position was used to drive an additional voice coil translation stage in the reference arm of the TS-OCT system to correct for axial eye motion. Currently, the correction can be performed with an update rate of ~200Hz. The TS-OCT instrument is operated with a line scan rate of 4000 transversal lines per second which enables simultaneous SLO/OCT imaging at a frame rate of 40fps. 3D data of the human retina with isotropic high resolution, that was sufficient to visualize the human cone mosaic in vivo, is presented.

The distinguishing effects of low-intensity electromagnetic radiation of different extremely high frequencies on Enterococcus hirae: growth rate inhibition and scanning electron microscopy analysis.

PubMed

Hovnanyan, K; Kalantaryan, V; Trchounian, A

2017-09-01

A low-intensity electromagnetic field of extremely high frequency has inhibitory and stimulatory effects on bacteria, including Enterococcus hirae. It was shown that the low-intensity (the incident power density of 0·06 mW cm -2 ) electromagnetic field at the frequencies of 51·8 GHz and 53 GHz inhibited E. hirae ATCC 9790 bacterial growth rate; a stronger effect was observed with 53 GHz, regardless of exposure duration (0·5 h, 1 h or 2 h). Scanning electron microscopy analysis of these effects has been done; the cells were of spherical shape. Electromagnetic field at 53 GHz, but not 51·8 GHz, changed the cell size-the diameter was enlarged 1·3 fold at 53 GHz. These results suggest the difference in mechanisms of action on bacteria for electromagnetic fields at 51·8 GHz and 53 GHz. A stronger inhibitory effect of low-intensity electromagnetic field on Enterococcus hirae ATCC 9790 bacterial growth rate was observed with 53 GHz vs 51·8 GHz, regardless of exposure duration. Scanning electron microscopy analysis showed that almost all irradiated cells in the population have spherical shapes similar to nonirradiated ones, but they have increased diameters in case of irradiated cells at 53 GHz, but not 51·8 GHz. The results are novel, showing distinguishing effects of low-intensity electromagnetic field of different frequencies. They could be applied in treatment of food and different products in medicine and veterinary, where E. hirae plays an important role. © 2017 The Society for Applied Microbiology.

Water Exchange Rate Constant as a Biomarker of Treatment Efficacy in Patients With Brain Metastases Undergoing Stereotactic Radiosurgery

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

Mehrabian, Hatef, E-mail: hatef.mehrabian@sri.utoronto.ca; Physical Sciences, Sunnybrook Research Institute, Toronto, Ontario; Desmond, Kimberly L.

Purpose: This study was designed to evaluate whether changes in metastatic brain tumors after stereotactic radiosurgery (SRS) can be seen with quantitative MRI early after treatment. Methods and Materials: Using contrast-enhanced MRI, a 3-water-compartment tissue model consisting of intracellular (I), extracellular-extravascular (E), and vascular (V) compartments was used to assess the intra–extracellular water exchange rate constant (k{sub IE}), efflux rate constant (k{sub ep}), and water compartment volume fractions (M{sub 0,I}, M{sub 0,E}, M{sub 0,V}). In this prospective study, 19 patients were MRI-scanned before treatment and 1 week and 1 month after SRS. The change in model parameters between the pretreatment and 1-week posttreatmentmore » scans was correlated to the change in tumor volume between pretreatment and 1-month posttreatment scans. Results: At 1 week k{sub IE} differentiated (P<.001) tumors that had partial response from tumors with stable and progressive disease, and a high correlation (R=−0.76, P<.001) was observed between early changes in the k{sub IE} and tumor volume change 1 month after treatment. Other model parameters had lower correlation (M{sub 0,E}) or no correlation (k{sub ep}, M{sub 0,V}). Conclusions: This is the first study that measured k{sub IE} early after SRS, and it found that early changes in k{sub IE} (1 week after treatment) highly correlated with long-term tumor response and could predict the extent of tumor shrinkage at 1 month after SRS.« less

Confocal Laser Scanning Microscopy, a New In Vivo Diagnostic Tool for Schistosomiasis

PubMed Central

Holtfreter, Martha Charlotte; Nohr-Łuczak, Constanze; Guthoff, Rudolf Friedrich; Reisinger, Emil Christian

2012-01-01

Background The gold standard for the diagnosis of schistosomiasis is the detection of the parasite's characteristic eggs in urine, stool, or rectal and bladder biopsy specimens. Direct detection of eggs is difficult and not always possible in patients with low egg-shedding rates. Confocal laser scanning microscopy (CLSM) permits non-invasive cell imaging in vivo and is an established way of obtaining high-resolution images and 3-dimensional reconstructions. Recently, CLSM was shown to be a suitable method to visualize Schistosoma mansoni eggs within the mucosa of dissected mouse gut. In this case, we evaluated the suitability of CLSM to detect eggs of Schistosoma haematobium in a patient with urinary schistosomiasis and low egg-shedding rates. Methodology/Principal Findings The confocal laser scanning microscope used in this study was based on a scanning laser system for imaging the retina of a living eye, the Heidelberg Retina Tomograph II, in combination with a lens system (image modality). Standard light cystoscopy was performed using a rigid cystoscope under general anaesthesia. The CLSM endoscope was then passed through the working channel of the rigid cystoscope. The mucosal tissue of the bladder was scanned using CLSM. Schistoma haematobium eggs appeared as bright structures, with the characteristic egg shape and typical terminal spine. Conclusion/Significance We were able to detect schistosomal eggs in the urothelium of a patient with urinary schistosomiasis. Thus, CLSM may be a suitable tool for the diagnosis of schistosomiasis in humans, especially in cases where standard diagnostic tools are not suitable. PMID:22529947

Graphene based nanocomposite hybrid electrodes for supercapacitors

NASA Astrophysics Data System (ADS)

Aphale, Ashish N.

There is an unmet need to develop high performance energy storage systems (ESS), capable of storing energy from both renewable and non-renewable sources to meet the current energy crisis and depletion of non-renewable sources. Amongst many available ESS, supercapacitors (ECs) are the most promising because they exhibit a high charge/discharge rate and power density, along with a long cycle life. The possibility of exploring the use of atomically thin carbon allotropes like graphene, carbon nanotubes (CNTs) and electrically conducting polymers (ECPs) such as polypyrrole (PPy) has been studied as a high performance conducting electrodes in supercapacitor application. A novel templated sustainable nanocomposite electrode has been fabricated using cellulose extracted from Cladophora c. aegagropila algae as component of the assembled supercapacitor device which later has been transitioned to a unique template-less freestanding nanocomposite supercapacitor electrode. The specific capacitance of polypyrrole-graphene-cellulose nanocomposite as calculated from cyclic voltammetry curve is 91.5 F g -1 at the scan rate 50 m Vs-1 in the presence of 1M NaCl electrolyte. The open circuit voltage of the device with polypyrrole -graphene-cellulose electrode was found to be around 225 m V and that of the polypyrrole -cellulose device is only 53 m V without the presence of graphene in the nanocomposite electrode. Understanding the fundamentals by fabricating template nanocomposite electrode, it led to fabricate a unique nanocomposite template-less freestanding film which comprises of polypyrrole-graphene-CNT hybrid. Various experiments have been performed using different electrolytes such ascorbic acid, sodium sulfate and sulfuric acid in different scan rates. The specific capacitance of polypyrrole-graphene-CNT nanocomposite with 0.1 wt% of graphene-CNT, as calculated from cyclic voltammetry curve is 450 F g-1 at the scan rate 5 m V s-1. For the first time a nanofibrous membrane has been developed as a separator which acts as an electrolyte reservoir and ionic diffusion membrane. The performance of the fabricated supercapacitor device has been analyzed using a multimeter and compared with a conventional alkaline (1.5 V) battery. Lighting up of 2.2 V light emitting diode has been demonstrated using the fabricated supercapacitor.

Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks.

PubMed

Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

2018-06-22

In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s -1 to 20 V s -1 , and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s -1 , suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

Ultrahigh-power supercapacitors based on highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon frameworks

NASA Astrophysics Data System (ADS)

Yan, Pengtao; Zhang, Xuesha; Hou, Meiling; Liu, Yanyan; Liu, Ting; Liu, Kang; Zhang, Ruijun

2018-06-01

In order to develop energy storage devices with high power performance, electrodes should hold well-defined pathways for efficient ionic and electronic transport. Herein, we demonstrate a highly conductive graphene nanosheet/nanometer-sized carbide-derived carbon framework (hcGNS/nCDC). In this architecture, nCDC possesses short transport paths for electrolyte ions, thus ensuring the rapid ions transportation. The excellent electrical conductivity of hcGNS can reduce the electrode internal resistance for the supercapacitor and thus endows the hcGNS/nCDC composite electrodes with excellent electronic transportation performance. Electrochemical measurements show that the cyclic voltammogram of hcGNS/nCDC can maintain a rectangular-like shape with the increase of the scan rate from 5 mV s‑1 to 20 V s‑1, and the specific capacitance retention is up to 51% even at a high scan rate of 20 V s‑1, suggesting ultrahigh power performance, which, to the best of our knowledge, is among the best power performances reported so far for the carbon materials. Furthermore, the hcGNS/nCDC composite also shows an excellent cycling stability (no drop in its capacitance occurs even after 10000 cycles). This work demonstrates the advantage in the ultrahigh power performance for the framework having both short transport pathways for electrolyte ions and high electrical conductivity.

Does MRI scan acceleration affect power to track brain change?

PubMed

Ching, Christopher R K; Hua, Xue; Hibar, Derrek P; Ward, Chadwick P; Gunter, Jeffrey L; Bernstein, Matt A; Jack, Clifford R; Weiner, Michael W; Thompson, Paul M

2015-01-01

The Alzheimer's Disease Neuroimaging Initiative recently implemented accelerated T1-weighted structural imaging to reduce scan times. Faster scans may reduce study costs and patient attrition by accommodating people who cannot tolerate long scan sessions. However, little is known about how scan acceleration affects the power to detect longitudinal brain change. Using tensor-based morphometry, no significant difference was detected in numerical summaries of atrophy rates from accelerated and nonaccelerated scans in subgroups of patients with Alzheimer's disease, early or late mild cognitive impairment, or healthy controls over a 6- and 12-month scan interval. Whole-brain voxelwise mapping analyses revealed some apparent regional differences in 6-month atrophy rates when comparing all subjects irrespective of diagnosis (n = 345). No such whole-brain difference was detected for the 12-month scan interval (n = 156). Effect sizes for structural brain changes were not detectably different in accelerated versus nonaccelerated data. Scan acceleration may influence brain measures but has minimal effects on tensor-based morphometry-derived atrophy measures, at least over the 6- and 12-month intervals examined here. Copyright © 2015 Elsevier Inc. All rights reserved.

Detailed fetal anatomy assessment in the first trimester at 11, 12 and 13 weeks of gestation.

PubMed

Luchi, Carlo; Schifano, Martina; Sacchini, Clara; Nanini, Chiara; Sceusa, Francesca; Capriello, Patrizio; Genazzani, Andrea R

2012-06-01

The aim of the present observational study was to evaluate the feasibility of a morphological scan and determine the detection rate of fetal organs, structures and systems in the first trimester of pregnancy. 977 single pregnant women attending our Fetal Medicine Section to undergo first trimester screening for aneuploidies were enrolled and divided into three groups depending on gestational age and crown-rump-length measurement. Scans targeted on a total of 26 fetal anatomical structures were performed by a single operator. The overall detection rate was 96% at 11 weeks and reached 100% at 12 and 13 weeks, with a significant statistical difference between 11 and 12/13 weeks for the majority of the investigated fetal anatomical structures. Evaluation of most part of the fetal anatomical structures is feasible with high accuracy in the first trimester. Visualization of the majority of the targeted fetal organs improves from 11 to 13 weeks.

Ethanedithiol-treated manganese oxide nanoparticles for rapidly responsive and transparent supercapacitors

NASA Astrophysics Data System (ADS)

Ryu, Ilhwan; Kim, Green; Park, Dasom; Yim, Sanggyu

2015-11-01

Metal oxide nanoparticles (NPs) provide a large surface area and short diffusion pathways for ions in supercapacitor electrode materials. However, binders and conductive additives used for tight connections with current collectors and improved conductivity hamper these benefits. In this work, we successfully fix manganese oxide (Mn3O4) NPs onto ITO current collectors by a simple 1,2-ethanedithiol (EDT) treatment without using any binders or conductive additives. As compared to the electrode fabricated using binder-mixed Mn3O4 NPs, the EDT-treated electrode shows significantly improved specific capacitance of 403 F g-1 at a scan rate of 10 mV s-1. The EDT-treatment is more effective at higher scan rates. The specific capacitances, 278 F g-1 at 100 mV s-1 and 202 F g-1 at 200 mV s-1, are larger than those reported so far at scan rates ≥100 mV s-1. The deconvolution of capacitive elements indicates that these improved capacitive properties are attributed to large insertion elements of the binder-free NP electrodes. Furthermore, this additive-free electrode is highly transparent and can be easily fabricated by simple spray-coating on various substrates including polymer films, implying that this new method is promising for the fabrication of large-area, transparent and flexible electrodes for next-generation supercapacitors.

Megahertz ultra-wide-field swept-source retina optical coherence tomography compared to current existing imaging devices.

PubMed

Reznicek, Lukas; Klein, Thomas; Wieser, Wolfgang; Kernt, Marcus; Wolf, Armin; Haritoglou, Christos; Kampik, Anselm; Huber, Robert; Neubauer, Aljoscha S

2014-06-01

To investigate the image quality of wide-angle cross-sectional and reconstructed fundus images based on ultra-megahertz swept-source Fourier domain mode locking (FDML) OCT compared to current generation diagnostic devices. A 1,050 nm swept-source FDML OCT system was constructed running at 1.68 MHz A-scan rate covering approximately 70° field of view. Twelve normal eyes were imaged with the device applying an isotropically dense sampling protocol (1,900 × 1,900 A-scans) with a fill factor of 100 %. Obtained OCT scan image quality was compared with two commercial OCT systems (Heidelberg Spectralis and Stratus OCT) of the same 12 eyes. Reconstructed en-face fundus images from the same FDML-OCT data set were compared to color fundus, infrared and ultra-wide-field scanning laser images (SLO). Comparison of cross-sectional scans showed a high overall image quality of the 15× averaged FDML images at 1.68 MHz [overall quality grading score: 8.42 ± 0.52, range 0 (bad)-10 (excellent)] comparable to current spectral-domain OCTs (overall quality grading score: 8.83 ± 0.39, p = 0.731). On FDML OCT, a dense 3D data set was obtained covering also the central and mid-peripheral retina. The reconstructed FDML OCT en-face fundus images had high image quality comparable to scanning laser ophthalmoscope (SLO) as judged from retinal structures such as vessels and optic disc. Overall grading score was 8.36 ± 0.51 for FDML OCT vs 8.27 ± 0.65 for SLO (p = 0.717). Ultra-wide-field megahertz 3D FDML OCT at 1.68 MHz is feasible, and provides cross-sectional image quality comparable to current spectral-domain OCT devices. In addition, reconstructed en-face visualization of fundus images result in a wide-field view with high image quality as compared to currently available fundus imaging devices. The improvement of >30× in imaging speed over commercial spectral-domain OCT technology enables high-density scan protocols leading to a data set for high quality cross-sectional and en-face images of the posterior segment.

Fiber optic light collection system for scanning-tunneling-microscope-induced light emission.

PubMed

Watkins, Neil J; Long, James P; Kafafi, Zakya H; Mäkinen, Antti J

2007-05-01

We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

Link Adaptation for Mitigating Earth-To-Space Propagation Effects on the NASA SCaN Testbed

NASA Technical Reports Server (NTRS)

Kilcoyne, Deirdre K.; Headley, William C.; Leffke, Zach J.; Rowe, Sonya A.; Mortensen, Dale J.; Reinhart, Richard C.; McGwier, Robert W.

2016-01-01

In Earth-to-Space communications, well-known propagation effects such as path loss and atmospheric loss can lead to fluctuations in the strength of the communications link between a satellite and its ground station. Additionally, the typically unconsidered effect of shadowing due to the geometry of the satellite and its solar panels can also lead to link degradation. As a result of these anticipated channel impairments, NASA's communication links have been traditionally designed to handle the worst-case impact of these effects through high link margins and static, lower rate, modulation formats. The work presented in this paper aims to relax these constraints by providing an improved trade-off between data rate and link margin through utilizing link adaptation. More specifically, this work provides a simulation study on the propagation effects impacting NASA's SCaN Testbed flight software-defined radio (SDR) as well as proposes a link adaptation algorithm that varies the modulation format of a communications link as its signal-to-noise ratio fluctuates. Ultimately, the models developed in this work will be utilized to conduct real-time flight experiments on-board the NASA SCaN Testbed.

Management of paediatric periorbital cellulitis: Our experience of 243 children managed according to a standardised protocol 2012-2015.

PubMed

Crosbie, Robin A; Nairn, Jonathan; Kubba, Haytham

2016-08-01

Paediatric periorbital cellulitis is a common condition. Accurate assessment can be challenging and appropriate use of CT imaging is essential. We audited admissions to our unit over a four year period, with reference to CT scanning and adherence to our protocol. Retrospective audit of paediatric patients admitted with periorbital cellulitis, 2012-2015. Total of 243 patients included, mean age 4.7 years with slight male predominance, the median length of admission was 2 days. 48/243 (20%) underwent CT during admission, 25 (52%) of these underwent surgical drainage. As per protocol, CT brain performed with all orbital scans; no positive intracranial findings on any initial scan. Three children developed intracranial complications subsequently; all treated with antibiotics. Our re-admission rate within 30 days was 2.5%. Our audit demonstrates benefit of standardising practice and the low CT rate, with high percentage taken to theatre and no missed abscesses, supports the protocol. There may be an argument to avoid CT brain routinely in all initial imaging sequences in those children without neurological signs or symptoms. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Carbon-polyaniline nanocomposites as supercapacitor materials

NASA Astrophysics Data System (ADS)

Sathish Kumar, M.; Yamini Yasoda, K.; Batabyal, Sudip Kumar; Kothurkar, Nikhil K.

2018-04-01

Polyaniline-based nanocomposites containing carbon nanotubes (CNT), reduced graphene oxide (rGO) and mixture of CNTs and rGO were synthesized. UV-visible spectroscopy and FT-IR spectroscopy confirmed the presence of polyaniline (PANi) and carbon nanomaterials. Scanning electron microscopy revealed that the neat PANi had a granular morphology, which can lead to increased electrical resistance to high interfacial resistance between domains of PANi. Cyclic voltammetry of PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO showed that in general, specific capacitance reduces with increasing scan rate within the range (10–100 mV s‑1). Also the specific capacitance values at any given scan rate within the above range, for PANi, PANi/CNT, PANi/rGO and PANi/CNT/rGO were found to be in increasing order. The specific capacitance of the PANi/CNT/rGO nanocomposite as measured by galvanostatic charge-discharge measurements, was found to be 312.5 F g‑1. The introduction of the carbon nanomaterials (CNTs, rGO) in PANi in general leads to improved specific capacitance, while the addition of CNTs and rGO together leads to synergistic improvement in the specific capacitance, owing to a combination of factors.

Using YOLO based deep learning network for real time detection and localization of lung nodules from low dose CT scans

NASA Astrophysics Data System (ADS)

Ramachandran S., Sindhu; George, Jose; Skaria, Shibon; V. V., Varun

2018-02-01

Lung cancer is the leading cause of cancer related deaths in the world. The survival rate can be improved if the presence of lung nodules are detected early. This has also led to more focus being given to computer aided detection (CAD) and diagnosis of lung nodules. The arbitrariness of shape, size and texture of lung nodules is a challenge to be faced when developing these detection systems. In the proposed work we use convolutional neural networks to learn the features for nodule detection, replacing the traditional method of handcrafting features like geometric shape or texture. Our network uses the DetectNet architecture based on YOLO (You Only Look Once) to detect the nodules in CT scans of lung. In this architecture, object detection is treated as a regression problem with a single convolutional network simultaneously predicting multiple bounding boxes and class probabilities for those boxes. By performing training using chest CT scans from Lung Image Database Consortium (LIDC), NVIDIA DIGITS and Caffe deep learning framework, we show that nodule detection using this single neural network can result in reasonably low false positive rates with high sensitivity and precision.

Nanoporous carbon derived from agro-waste pineapple leaves for supercapacitor electrode

NASA Astrophysics Data System (ADS)

Sodtipinta, Jedsada; Amornsakchai, Taweechai; Pakawatpanurut, Pasit

2017-09-01

By using KOH as the chemical activating agent in the synthesis, the activated carbon derived from pineapple leaf fiber (PALF) was prepared. The structure, morphology, and the surface functional groups of the as-prepared activated carbon were investigated using x-ray diffraction, field emission scanning electron microscope equipped with energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. The electrochemical behavior and performance of the as-synthesized activated carbon electrode were measured using the cyclic voltammetry and the electrochemical impedance spectroscopy in 1 M Na2SO4 electrolyte solution in three-electrode setup. The activated carbon electrode exhibited the specific capacitance of 131.3 F g-1 at a scan rate of 5 mV s-1 with excellent cycling stability. The capacitance retention after 1000 cycles was about 97% of the initial capacitance at a scan rate of 30 mV s-1. Given these good electrochemical properties along with the high abundance of PALF, this activated carbon electrode has the potential to be one of the materials for future large-scale production of the electrochemical capacitors. Invited talk at 5th Thailand International Nanotechnology Conference (Nano Thailand-2016), 27-29 November 2016, Nakhon Ratchasima, Thailand.

Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements

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

Nishizawa, T., E-mail: nishizawa@wisc.edu; Nornberg, M. D.; Den Hartog, D. J.

2016-11-15

The upgraded spectrometer used for charge exchange recombination spectroscopy on the Madison Symmetric Torus resolves emission fluctuations up to 400 kHz. The transimpedance amplifier’s cutoff frequency was increased based upon simulations comparing the change in the measured photon counts for time-dynamic signals. We modeled each signal-processing stage of the diagnostic and scanned the filtering frequency to quantify the uncertainty in the photon counting rate. This modeling showed that uncertainties can be calculated based on assuming each amplification stage is a Poisson process and by calibrating the photon counting rate with a DC light source to address additional variation.

Upgrading a high-throughput spectrometer for high-frequency (<400 kHz) measurements

NASA Astrophysics Data System (ADS)

Nishizawa, T.; Nornberg, M. D.; Den Hartog, D. J.; Craig, D.

2016-11-01

The upgraded spectrometer used for charge exchange recombination spectroscopy on the Madison Symmetric Torus resolves emission fluctuations up to 400 kHz. The transimpedance amplifier's cutoff frequency was increased based upon simulations comparing the change in the measured photon counts for time-dynamic signals. We modeled each signal-processing stage of the diagnostic and scanned the filtering frequency to quantify the uncertainty in the photon counting rate. This modeling showed that uncertainties can be calculated based on assuming each amplification stage is a Poisson process and by calibrating the photon counting rate with a DC light source to address additional variation.

Sample exchange by beam scanning with applications to noncollinear pump-probe spectroscopy at kilohertz repetition rates.

PubMed

Spencer, Austin P; Hill, Robert J; Peters, William K; Baranov, Dmitry; Cho, Byungmoon; Huerta-Viga, Adriana; Carollo, Alexa R; Curtis, Anna C; Jonas, David M

2017-06-01

In laser spectroscopy, high photon flux can perturb the sample away from thermal equilibrium, altering its spectroscopic properties. Here, we describe an optical beam scanning apparatus that minimizes repetitive sample excitation while providing shot-to-shot sample exchange for samples such as cryostats, films, and air-tight cuvettes. In this apparatus, the beam crossing point is moved within the focal plane inside the sample by scanning both tilt angles of a flat mirror. A space-filling spiral scan pattern was designed that efficiently utilizes the sample area and mirror scanning bandwidth. Scanning beams along a spiral path is shown to increase the average number of laser shots that can be sampled before a spot on the sample cell is resampled by the laser to ∼1700 (out of the maximum possible 2500 for the sample area and laser spot size) while ensuring minimal shot-to-shot spatial overlap. Both an all-refractive version and an all-reflective version of the apparatus are demonstrated. The beam scanning apparatus does not measurably alter the time delay (less than the 0.4 fs measurement uncertainty), the laser focal spot size (less than the 2 μm measurement uncertainty), or the beam overlap (less than the 3.3% measurement uncertainty), leading to pump-probe and autocorrelation signal transients that accurately characterize the equilibrium sample.

ZnO synthesized in air by fs laser irradiation on metallic Zn thin films

NASA Astrophysics Data System (ADS)

Esqueda-Barrón, Y.; Herrera, M.; Camacho-López, S.

2018-05-01

We present results on rapid femtosecond laser synthesis of nanostructured ZnO. We used metallic Zn thin films to laser scan along straight tracks, until forming nanostructured ZnO. The synthesis dependence on laser irradiation parameters such as the per pulse fluence, integrated fluence, laser scan speed, and number of scans were explored carefully. SEM characterization showed that the morphology of the obtained ZnO is dictated by the integrated fluence and the laser scan speed; micro Raman and XRD results allowed to identify optimal laser processing conditions for getting good quality ZnO; and cathodoluminescence measurements demonstrated that a single laser scan at high per pulse laser fluence, but a medium integrated laser fluence and a medium laser scan speed favors a low density of point-defects in the lattice. Electrical measurements showed a correlation between resistivity of the laser produced ZnO and point-defects created during the synthesis. Transmittance measurements showed that, the synthesized ZnO can reach down to the supporting fused silica substrate under the right laser irradiation conditions. The physical mechanism for the formation of ZnO, under ultrashort pulse laser irradiation, is discussed in view of the distinct times scales given by the laser pulse duration and the laser pulse repetition rate.

Ultrahigh speed Spectral / Fourier domain OCT ophthalmic imaging at 70,000 to 312,500 axial scans per second

PubMed Central

Potsaid, Benjamin; Gorczynska, Iwona; Srinivasan, Vivek J.; Chen, Yueli; Jiang, James; Cable, Alex; Fujimoto, James G.

2009-01-01

We demonstrate ultrahigh speed spectral / Fourier domain optical coherence tomography (OCT) using an ultrahigh speed CMOS line scan camera at rates of 70,000 - 312,500 axial scans per second. Several design configurations are characterized to illustrate trade-offs between acquisition speed, resolution, imaging range, sensitivity and sensitivity roll-off performance. Ultrahigh resolution OCT with 2.5 - 3.0 micron axial image resolution is demonstrated at ∼ 100,000 axial scans per second. A high resolution spectrometer design improves sensitivity roll-off and imaging range performance, trading off imaging speed to 70,000 axial scans per second. Ultrahigh speed imaging at >300,000 axial scans per second with standard image resolution is also demonstrated. Ophthalmic OCT imaging of the normal human retina is investigated. The high acquisition speeds enable dense raster scanning to acquire densely sampled volumetric three dimensional OCT (3D-OCT) data sets of the macula and optic disc with minimal motion artifacts. Imaging with ∼ 8 - 9 micron axial resolution at 250,000 axial scans per second, a 512 × 512 × 400 voxel volumetric 3D-OCT data set can be acquired in only ∼ 1.3 seconds. Orthogonal registration scans are used to register OCT raster scans and remove residual axial eye motion, resulting in 3D-OCT data sets which preserve retinal topography. Rapid repetitive imaging over small volumes can visualize small retinal features without motion induced distortions and enables volume registration to remove eye motion. Cone photoreceptors in some regions of the retina can be visualized without adaptive optics or active eye tracking. Rapid repetitive imaging of 3D volumes also provides dynamic volumetric information (4D-OCT) which is shown to enhance visualization of retinal capillaries and should enable functional imaging. Improvements in the speed and performance of 3D-OCT volumetric imaging promise to enable earlier diagnosis and improved monitoring of disease progression and response to therapy in ophthalmology, as well as have a wide range of research and clinical applications in other areas. PMID:18795054

High-resolution raster scan optoacoustic mesoscopy of genetically modified drosophila pupae

NASA Astrophysics Data System (ADS)

Omar, Murad; Gateau, Jérôme; Ntziachristos, Vasilis

2014-03-01

Optoacoutic mesoscopy aims to bridge the gap between optoacoustic microscopy and optoacoustic tomography. We have developed a setup for optoacoustic mesoscopy where we use a high frequency, high numerical aperture spherically focused ultrasound transducer, with a wide bandwidth of 25-125 MHz. The excitation is performed using a diode laser capable of >500 μJ/pulse, 1.8ns pulse width, 1.4 kHz pulse repetition rate, at 515 nm. The system is capable to penetrate more than 5 mm with a resolution of 7 μm axially and 30 μm transversally. Using high-speed stages and scanning the transducer in a quasi-continuous mode, a field of view of 2×2 mm2 is scanned in less than 2 minutes. The system is suitable for imaging biological samples that have a diameter of 1-5 mm; zebrafish, drosophila melanogaster, and thin biological samples such as the mouse ear and mouse extremities. We have used our mesoscopic setup to generate 3- dimensional images of genetically modified drosophila fly, and drosophila pupae expressing GFP from the wings, high resolution images were generated in both cases, in the fly we can see the wings, the legs, the eyes, and the shape of the body. In the pupae the outline of the pupae, the spiracles at both ends and a strong signal corresponding to the location of the future wings are observed.

SU-F-I-40: Impact of Scan Length On Patient Dose in Abdomen/pelvis CT Diagnosis

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

Park, I; Song, J; Kim, K

Purpose: To analysis the impact of scan length on patient doses in abdomen/pelvis CT diagnosis of each hospital. Methods: Scan length of 7 hospitals from abdomen/pelvis CT diagnosis was surveyed in Korea. Surveyed scan lengths were additional distance above diaphragm and distance below pubic symphysis except for standard scan range between diaphragm and pubic symphysis. Patient dose was estimated for adult male and female according to scan length of each hospital. CT-Expo was used to estimate the patient dose under identical equipment settings (120 kVp, 100 mAs, 10 mm collimation width, etc.) except scan length. Effective dose was calculated bymore » using tissue weighting factor of ICRP 103 recommendation. Increase rate of effective dose was calculated comparing with effective dose of standard scan range Results: Scan lengths of abdomen/pelvis CT diagnosis of each hospital were different. Also effective dose was increased with increasing the scan length. Generally increasing the distance above diaphragm caused increase of effective dose of male and female, but increasing the distance below pubic symphysis caused increase of effective dose of male. Conclusion: We estimated the patient dose according to scan length of each hospital in abdomen/pelvis CT diagnosis. Effective dose was increased by increasing the scan length because dose of organs with high tissue weighting factor such as lung, breast, testis were increased. Scan length is important factor on patient dose in CT diagnosis. If radiologic technologist interested in patient dose, decreasing the unnecessary scan length will decrease the risk of patients from radiation. This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI13C0004).« less

Implementation of Time-Resolved Step-Scan Fourier Transform Infrared (FT-IR) Spectroscopy Using a kHz Repetition Rate Pump Laser

PubMed Central

MAGANA, DONNY; PARUL, DZMITRY; DYER, R. BRIAN; SHREVE, ANDREW P.

2011-01-01

Time-resolved step-scan Fourier transform infrared (FT-IR) spectroscopy has been shown to be invaluable for studying excited-state structures and dynamics in both biological and inorganic systems. Despite the established utility of this method, technical challenges continue to limit the data quality and more wide ranging applications. A critical problem has been the low laser repetition rate and interferometer stepping rate (both are typically 10 Hz) used for data acquisition. Here we demonstrate significant improvement in the quality of time-resolved spectra through the use of a kHz repetition rate laser to achieve kHz excitation and data collection rates while stepping the spectrometer at 200 Hz. We have studied the metal-to-ligand charge transfer excited state of Ru(bipyridine)3Cl2 in deuterated acetonitrile to test and optimize high repetition rate data collection. Comparison of different interferometer stepping rates reveals an optimum rate of 200 Hz due to minimization of long-term baseline drift. With the improved collection efficiency and signal-to-noise ratio, better assignments of the MLCT excited-state bands can be made. Using optimized parameters, carbonmonoxy myoglobin in deuterated buffer is also studied by observing the infrared signatures of carbon monoxide photolysis upon excitation of the heme. We conclude from these studies that a substantial increase in performance of ss-FT-IR instrumentation is achieved by coupling commercial infrared benches with kHz repetition rate lasers. PMID:21513597

Preprocessing of A-scan GPR data based on energy features

NASA Astrophysics Data System (ADS)

Dogan, Mesut; Turhan-Sayan, Gonul

2016-05-01

There is an increasing demand for noninvasive real-time detection and classification of buried objects in various civil and military applications. The problem of detection and annihilation of landmines is particularly important due to strong safety concerns. The requirement for a fast real-time decision process is as important as the requirements for high detection rates and low false alarm rates. In this paper, we introduce and demonstrate a computationally simple, timeefficient, energy-based preprocessing approach that can be used in ground penetrating radar (GPR) applications to eliminate reflections from the air-ground boundary and to locate the buried objects, simultaneously, at one easy step. The instantaneous power signals, the total energy values and the cumulative energy curves are extracted from the A-scan GPR data. The cumulative energy curves, in particular, are shown to be useful to detect the presence and location of buried objects in a fast and simple way while preserving the spectral content of the original A-scan data for further steps of physics-based target classification. The proposed method is demonstrated using the GPR data collected at the facilities of IPA Defense, Ankara at outdoor test lanes. Cylindrically shaped plastic containers were buried in fine-medium sand to simulate buried landmines. These plastic containers were half-filled by ammonium nitrate including metal pins. Results of this pilot study are demonstrated to be highly promising to motivate further research for the use of energy-based preprocessing features in landmine detection problem.

Total enbloc spondylectomy for metastatic high grade spinal tumors: Early results

PubMed Central

Patil, Sanganagouda S; Nene, Abhay M

2016-01-01

Background: High grade metastatic spinal tumors are most common and are invasive. These patients can succumb to disease progression if not treated timely. Although considered as invasive and morbid, total enbloc spondylectomy (TES) in selected cases has better survival rates. The authors describe the results of TES for high grade metastatic spinal tumors. Materials and Methods: Five patients (four females and one male) underwent TES for solitary metastatic vertebral lesion between November 2012 and January 2014. These patients presented to us with spinal instability, unrelenting severe spinal pain and/or with severe progressive radiculopathy. Average age was 46.2 years (range 39–62 years). After complete investigations, computed tomography scan, magnetic resonance imaging scan and positron emission tomography (PET) scan, it was confirmed that these patients had high grade solitary vertebral metastatic tumor. Results: Average duration of followup was 18 months (range 16–20 months). The average preoperative visual analog scale score of 9.4 (range 9–10) improved to 2 (range 1–4) at last followup. Average blood loss was 1440 mL (range 1000–2000 mL). Average duration of surgery was 198 min (range 180–240 min). Significant pain relief was noticed in each patient in the immediate postoperative period and during followups. These patients attained complete functional activities of daily living with in a month. The imaging showed implants in situ, no recurrence of tumor, and no activity on PET scan at the final followup. Conclusion: The present series shows favorable short term results of TES for solitary, metastatic, high grade vertebral body tumors by a team approach. PMID:27512215

Hierarchically porous MnO2 microspheres doped with homogeneously distributed Fe3O4 nanoparticles for supercapacitors.

PubMed

Zhu, Jian; Tang, Shaochun; Xie, Hao; Dai, Yuming; Meng, Xiangkang

2014-10-22

Hierarchically porous yet densely packed MnO2 microspheres doped with Fe3O4 nanoparticles are synthesized via a one-step and low-cost ultrasound assisted method. The scalable synthesis is based on Fe(2+) and ultrasound assisted nucleation and growth at a constant temperature in a range of 25-70 °C. Single-crystalline Fe3O4 particles of 3-5 nm in diameter are homogeneously distributed throughout the spheres and none are on the surface. A systematic optimization of reaction parameters results in isolated, porous, and uniform Fe3O4-MnO2 composite spheres. The spheres' average diameter is dependent on the temperature, and thus is controllable in a range of 0.7-1.28 μm. The involved growth mechanism is discussed. The specific capacitance is optimized at an Fe/Mn atomic ratio of r = 0.075 to be 448 F/g at a scan rate of 5 mV/s, which is nearly 1.5 times that of the extremely high reported value for MnO2 nanostructures (309 F/g). Especially, such a structure allows significantly improved stability at high charging rates. The composite has a capacitance of 367.4 F/g at a high scan rate of 100 mV/s, which is 82% of that at 5 mV/s. Also, it has an excellent cycling performance with a capacitance retention of 76% after 5000 charge/discharge cycles at 5 A/g.

Slowly digestible properties of lotus seed starch-glycerine monostearin complexes formed by high pressure homogenization.

PubMed

Chen, Bingyan; Jia, Xiangze; Miao, Song; Zeng, Shaoxiao; Guo, Zebin; Zhang, Yi; Zheng, Baodong

2018-06-30

Starch-lipid complexes were prepared using lotus seed starch (LS) and glycerin monostearate (GMS) via a high-pressure homogenization process, and the effect of high pressure homogenization (HPH) on the slow digestion properties of LS-GMS was investigated. The digestion profiles showed HPH treatment reduced the digestive rate of LS-GMS, and the extent of this change was dependent on homogenized pressure. Scanning electron microscopy displayed HPH treatment change the morphology of LS-GMS, with high pressure producing more compact block-shape structure to resist enzyme digestion. The results of Gel-permeation chromatography and Small-angle X-ray scattering revealed high homogenization pressure impacted molecular weight distribution and semi-crystalline region of complexes, resulting in the formation of new semi-crystalline with repeat unit distance of 16-18 nm and molecular weight distribution of 2.50-2.80 × 10 5  Da, which displayed strong enzymatic resistance. Differential scanning calorimeter results revealed new semi-crystalline lamellar may originate from type-II complexes that exhibited a high transition temperature. Copyright © 2018 Elsevier Ltd. All rights reserved.

Ultrasound Picture Archiving And Communication Systems

NASA Astrophysics Data System (ADS)

Koestner, Ken; Hottinger, C. F.

1982-01-01

The ideal ultrasonic image communication and storage system must be flexible in order to optimize speed and minimize storage requirements. Various ultrasonic imaging modalities are quite different in data volume and speed requirements. Static imaging, for example B-Scanning, involves acquisition of a large amount of data that is averaged or accumulated in a desired manner. The image is then frozen in image memory before transfer and storage. Images are commonly a 512 x 512 point array, each point 6 bits deep. Transfer of such an image over a serial line at 9600 baud would require about three minutes. Faster transfer times are possible; for example, we have developed a parallel image transfer system using direct memory access (DMA) that reduces the time to 16 seconds. Data in this format requires 256K bytes for storage. Data compression can be utilized to reduce these requirements. Real-time imaging has much more stringent requirements for speed and storage. The amount of actual data per frame in real-time imaging is reduced due to physical limitations on ultrasound. For example, 100 scan lines (480 points long, 6 bits deep) can be acquired during a frame at a 30 per second rate. In order to transmit and save this data at a real-time rate requires a transfer rate of 8.6 Megabaud. A real-time archiving system would be complicated by the necessity of specialized hardware to interpolate between scan lines and perform desirable greyscale manipulation on recall. Image archiving for cardiology and radiology would require data transfer at this high rate to preserve temporal (cardiology) and spatial (radiology) information.

Electrostatic Induced Stretch Growth of Homogeneous β-Ni(OH)2 on Graphene with Enhanced High-Rate Cycling for Supercapacitors

PubMed Central

Wu, Zhong; Huang, Xiao-Lei; Wang, Zhong-Li; Xu, Ji-Jing; Wang, Heng-Guo; Zhang, Xin-Bo

2014-01-01

Supercapacitors, as one of alternative energy devices, have been characterized by the rapid rate of charging and discharging, and high power density. But they are now challenged to achieve their potential energy density that is related to specific capacitance. Thus it is extremely important to make such materials with high specific capacitances. In this report, we have gained homogenous Ni(OH)2 on graphene by efficiently using of a facile and effective electrostatic induced stretch growth method. The electrostatic interaction triggers advantageous change in morphology and the ordered stacking of Ni(OH)2 nanosheets on graphene also enhances the crystallization of Ni(OH)2. When the as-prepared Ni(OH)2/graphene composite is applied to supercapacitors, they show superior electrochemical properties including high specific capacitance (1503 F g−1 at 2 mV s−1) and excellent cycling stability up to 6000 cycles even at a high scan rate of 50 mV s−1. PMID:24413283

A Comparative Study of Alternative Controls and Displays for by the Severely Physically Handicapped

NASA Technical Reports Server (NTRS)

Williams, D.; Simpson, C.; Barker, M.

1984-01-01

A modification of a row/column scanning system was investigated in order to increase the speed and accuracy with which communication aids can be accessed with one or two switches. A selection algorithm was developed and programmed in BASIC to automatically select individuals with the characteristic difficulty in controlling time dependent control and display systems. Four systems were compared: (1) row/column directed scan (2 switches); (2) row/column auto scan (1 switch); (3) row auto scan (1 switch); and (4) column auto scan (1 switch). For this sample population, there were no significant differences among systems for scan time to select the correct target. The row/column auto scan system resulted in significantly more errors than any of the other three systems. Thus, the most widely prescribed system for severely physically disabled individuals turns out for this group to have a higher error rate and no faster communication rate than three other systems that have been considered inappropriate for this group.

Socio-economic variation in CT scanning in Northern England, 1990-2002

PubMed Central

2012-01-01

Background Socio-economic status is known to influence health throughout life. In childhood, studies have shown increased injury rates in more deprived settings. Socio-economic status may therefore be related to rates of certain medical procedures, such as computed tomography (CT) scans. This study aimed to assess socio-economic variation among young people having CT scans in Northern England between 1990 and 2002 inclusive. Methods Electronic data were obtained from Radiology Information Systems of all nine National Health Service hospital Trusts in the region. CT scan data, including sex, date of scan, age at scan, number and type of scans were assessed in relation to quintiles of Townsend deprivation scores, obtained from linkage of postcodes with census data, using χ2 tests and Spearman rank correlations. Results During the study period, 39,676 scans were recorded on 21,089 patients, with 38,007 scans and 19,485 patients (11344 male and 8132 female) linkable to Townsend scores. The overall distributions of both scans and patients by quintile of Townsend deprivation scores were significantly different to the distributions of Townsend scores from the census wards included in the study (p < 0.0001). There was a significant association between type of scan and deprivation quintile (p < 0.0001), primarily due to the higher proportions of head scans in the three most deprived quintiles, and slightly higher proportions of chest scans and abdomen and pelvis scans in the least deprived groups. There was also a significant association (p < 0.0001) between the patient's age at the time of the CT scan and Townsend deprivation quintiles, with slightly increasing proportions of younger children with increasing deprivation. A similar association with age (p < 0.0001) was seen when restricting the data to include only the first scan of each patient. The number of scans per patient was also associated with Townsend deprivation quintiles (p = 0.014). Conclusions Social inequalities exist in the numbers of young people undergoing CT scans with those from deprived areas more likely to do so. This may reflect the rates of injuries in these individuals and implies that certain groups within the population may receive higher radiation doses than others due to medical procedures. PMID:22283843

A 5-mm piezo-scanning fiber device for high speed ultrafast laser microsurgery

PubMed Central

Ferhanoglu, Onur; Yildirim, Murat; Subramanian, Kaushik; Ben-Yakar, Adela

2014-01-01

Towards developing precise microsurgery tools for the clinic, we previously developed image-guided miniaturized devices using low repetition rate amplified ultrafast lasers for surgery. To improve the speed of tissue removal while reducing device diameter, here we present a new 5-mm diameter device that delivers high-repetition rate laser pulses for high speed ultrafast laser microsurgery. The device consists of an air-core photonic bandgap fiber (PBF) for the delivery of high energy pulses, a piezoelectric tube actuator for fiber scanning, and two aspheric lenses for focusing the light. Its inline optical architecture provides easy alignment and substantial size reduction to 5 mm diameter as compared to our previous MEMS-scanning devices while realizing improved intensity squared (two-photon) lateral and axial resolutions of 1.16 μm and 11.46 μm, respectively. Our study also sheds light on the maximum pulse energies that can be delivered through the air-core PBF and identifies cladding damage at the input facet of the fiber as the limiting factor. We have achieved a maximum energy delivery larger than 700 nJ at 92% coupling efficiency. An in depth analysis reveals how this value is greatly affected by possible slight misalignments of the beam during coupling and the measured small beam pointing fluctuations. In the absence of these imperfections, self-phase modulation becomes the limiting factor for the maximum energy delivery, setting the theoretical upper bound to near 2 μJ for a 1-m long, 7-μm, air-core PBF. Finally, the use of a 300 kHz repetition rate fiber laser enabled rapid ablation of 150 µm x 150 µm area within only 50 ms. Such ablation speeds can now allow the surgeons to translate the surgery device as fast as ~4 mm/s to continuously remove a thin layer of a 150 µm wide tissue. Thanks to a high optical transmission efficiency of the in-line optical architecture of the device and improved resolution, we could successfully perform ablation of scarred cheek pouch tissue, drilling through a thin slice. With further development, this device can serve as a precise and high speed ultrafast laser scalpel in the clinic. PMID:25071946

Dynamic in vivo imaging of small animal brain using pulsed laser diode-based photoacoustic tomography system.

PubMed

Upputuri, Paul Kumar; Pramanik, Manojit

2017-09-01

We demonstrate dynamic in vivo imaging using a low-cost portable pulsed laser diode (PLD)-based photoacoustic tomography system. The system takes advantage of an 803-nm PLD having high-repetition rate ∼7000  Hz combined with a fast-scanning single-element ultrasound transducer leading to a 5 s cross-sectional imaging. Cortical vasculature is imaged in scan time of 5 s with high signal-to-noise ratio ∼48. To examine the ability for dynamic imaging, we monitored the fast uptake and clearance process of indocyanine green in the rat brain. The system will find applications to study neurofunctional activities, characterization of pharmacokinetic, and biodistribution profiles in the development process of drugs or imaging agents. (2017) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

A compact Acousto-Optic Lens for 2D and 3D femtosecond based 2-photon microscopy.

PubMed

Kirkby, Paul A; Srinivas Nadella, K M Naga; Silver, R Angus

2010-06-21

We describe a high speed 3D Acousto-Optic Lens Microscope (AOLM) for femtosecond 2-photon imaging. By optimizing the design of the 4 AO Deflectors (AODs) and by deriving new control algorithms, we have developed a compact spherical AOL with a low temporal dispersion that enables 2-photon imaging at 10-fold lower power than previously reported. We show that the AOLM can perform high speed 2D raster-scan imaging (>150 Hz) without scan rate dependent astigmatism. It can deflect and focus a laser beam in a 3D random access sequence at 30 kHz and has an extended focusing range (>137 mum; 40X 0.8NA objective). These features are likely to make the AOLM a useful tool for studying fast physiological processes distributed in 3D space.

Towards Automated Nanomanipulation under Scanning Electron Microscopy

NASA Astrophysics Data System (ADS)

Ye, Xutao

Robotic Nanomaterial Manipulation inside scanning electron microscopes (SEM) is useful for prototyping functional devices and characterizing one-dimensional nanomaterial's properties. Conventionally, manipulation of nanowires has been performed via teleoperation, which is time-consuming and highly skill-dependent. Manual manipulation also has the limitation of low success rates and poor reproducibility. This research focuses on a robotic system capable of automated pick-place of single nanowires. Through SEM visual detection and vision-based motion control, the system transferred individual silicon nanowires from their growth substrate to a microelectromechanical systems (MEMS) device that characterized the nanowires' electromechanical properties. The performances of the nanorobotic pick-up and placement procedures were quantified by experiments. The system demonstrated automated nanowire pick-up and placement with high reliability. A software system for a load-lock-compatible nanomanipulation system is also designed and developed in this research.

Applying LED in full-field optical coherence tomography for gastrointestinal endoscopy

NASA Astrophysics Data System (ADS)

Yang, Bor-Wen; Wang, Yu-Yen; Juan, Yu-Shan; Hsu, Sheng-Jie

2015-08-01

Optical coherence tomography (OCT) has become an important medical imaging technology due to its non-invasiveness and high resolution. Full-field optical coherence tomography (FF-OCT) is a scanning scheme especially suitable for en face imaging as it employs a CMOS/CCD device for parallel pixels processing. FF-OCT can also be applied to high-speed endoscopic imaging. Applying cylindrical scanning and a right-angle prism, we successfully obtained a 360° tomography of the inner wall of an intestinal cavity through an FF-OCT system with an LED source. The 10-μm scale resolution enables the early detection of gastrointestinal lesions, which can increase detection rates for esophageal, stomach, or vaginal cancer. All devices used in this system can be integrated by MOEMS technology to contribute to the studies of gastrointestinal medicine and advanced endoscopy technology.

High enthalpy arc-heated plasma flow diagnostics by tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lin, Xin; Chen, Lianzhong; Zeng, Hui; Ou, Dongbin; Dong, Yonghui

2017-05-01

This paper reports the laser absorption measurements of atomic oxygen in the FD04 arc-heater at China Academy of Aerospace Aerodynamics (CAAA). An atomic oxygen absorption line at 777.19 nm is utilizied for detecting the population of electronically excited oxygen atom in an air plasma flow. A scanned-wavelength direct absorption mode is used in this study. The laser is scanned in wavelength across the absorption feature at a rate of 200 Hz. Under the assumption of thermal equilibrium, time-resolved temperature measurements are obtained on one line-of-sight in the arc-heater. The good agreement of the temperature inferred from the sonic throat method suggests the equilibrium assumption is valid. These results illustrate the feasibility of the diode laser sensors for flow parameters in high enthalpy arc-heated facilities.

PIP silicone breast implants: rupture rates based on the explantation of 676 implants in a single surgeon series.

PubMed

Quaba, Omar; Quaba, Awf

2013-09-01

To determine the true rupture rates of PIP implants from a large single surgeon cohort and to assess whether rupture rates varied depending on time of implant insertion. In addition, the efficacy of ultra sound scanning (USS) in determining rupture is examined. Predominantly prospectively based analysis of patient records, investigations and surgical findings. 338 patients (676 implants) were included in the study and they all had removal of their implants. The senior author operated on all patients at some stage of their treatment. 160 patients were imaged pre-operatively with USS. Patients had implants inserted between 1999 and 2007 for cosmetic breast augmentation. A total of 144 ruptured implants were removed from 119 patients, giving a rupture rate of 35.2% per patient and 21.3% per implant over a mean implantation period of 7.8 years. A statistical difference (P < 0.001) in rupture rates between implants inserted prior to 2003 and those inserted from 2003 was demonstrated, with higher failure rates in the latter group. There was a significant difference in rupture rates depending on pocket placement of the implants. The sensitivity and specificity of USS at detecting rupture was 90.6% and 98.3% respectively. A proportion of patients (29.4%) demonstrated loco-regional spread of silicone to the axilla on scanning. Our paper has confirmed high rates of PIP implant failure in the largest published series to date. The significant difference in rupture rates between implants inserted prior to 2003 and those after this time supports the view that industrial silicone was used in the devices after 2003. Implants are more likely to rupture if inserted in the sub muscular plane compared to the sub glandular plane. USS is highly effective at detecting rupture in PIP implants and loco-regional spread is high compared to other devices. We believe this paper provides hard data enabling more informed decision making for patients, clinicians and providers in what remains an active issue affecting thousands of women. Copyright © 2013 British Association of Plastic, Reconstructive and Aesthetic Surgeons. Published by Elsevier Ltd. All rights reserved.

Understanding the crack formation of graphite particles in cycled commercial lithium-ion batteries by focused ion beam - scanning electron microscopy

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

Lin, Na; Jia, Zhe; Wang, Zhihui

Here in this paper, the structure degradation of commercial Lithium-ion battery (LIB) graphite anodes with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystallinemore » graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.« less

Understanding the crack formation of graphite particles in cycled commercial lithium-ion batteries by focused ion beam - scanning electron microscopy

DOE PAGES

Lin, Na; Jia, Zhe; Wang, Zhihui; ...

2017-10-01

Here in this paper, the structure degradation of commercial Lithium-ion battery (LIB) graphite anodes with different cycling numbers and charge rates was investigated by focused ion beam (FIB) and scanning electron microscopy (SEM). The cross-section image of graphite anode by FIB milling shows that cracks, resulted in the volume expansion of graphite electrode during long-term cycling, were formed in parallel with the current collector. The crack occurs in the bulk of graphite particles near the lithium insertion surface, which might derive from the stress induced during lithiation and de-lithiation cycles. Subsequently, crack takes place along grain boundaries of the polycrystallinemore » graphite, but only in the direction parallel with the current collector. Furthermore, fast charge graphite electrodes are more prone to form cracks since the tensile strength of graphite is more likely to be surpassed at higher charge rates. Therefore, for LIBs long-term or high charge rate applications, the tensile strength of graphite anode should be taken into account.« less

Interrelationship of Cn2 & Eddy Dissipation rate based on Scintillometer and Doppler Lidar observations in complex terrain during the Perdigao Campaign 2017

NASA Astrophysics Data System (ADS)

Creegan, E. D.; Krishnamurthy, R.; Hocut, C. M.; Pattantyus, A.; Leo, L. S.; Wang, Y.; Fernando, H. J.; Bariteau, L.

2017-12-01

The Perdigao campaign is a joint EU/US science project designed to provide information on flow field(s) over complex terrain and through wind turbines at unprecedented high spatial and temporal resolution. The goal is to improve wind energy physics and overcome the current deficiencies of wind resource models. Topographically the Perdigao location is an expansion of the "double hill in crossflow", consisting of two parallel ridges along the NW-SE direction. The site was heavily instrumented with an array of towers (with multiple transects along the valley and across two ridges) and a large suite of ground based and aerial remote sensing platforms. On the outflow side of the NW ridge a scintillometer was emplaced with the line-of-sight (LOS) running adjacent to the towers comprising the NE transect from the ridgetop down to the base. Scanning lidars were placed at both ends of this LOS. Other instruments included a tethered lifting system (TLS), sodar, microwave radiometer, an energy budget flux tower and radiosonde releases. Scintillomoter data provides a quantitative measure of the intensity of optical turbulence, through the refractive index structure parameter, Cn2, where averaged Cn2 is often determined as a function of local differences in temperature, moisture, and wind velocity at discrete points. The refractive index structure parameter is also a function of the inner (dissipation) and outer (energy producing) turbulent scales. The scintillometer directly gives path averaged Cn2 and Eddy Dissipation rate along the LOS. Coplanar scans along the same path were synchronized using two scanning coherent Doppler lidars. Algorithms have been developed to estimate both eddy dissipation rate and Cn2 from Doppler lidar data effectively creating a new lidar data product. Additionally, from TLS measurements, Cn2 and dissipation rate are calculated using the high frequency spectra of the hot-wire sensor. In this work, measurements of Cn2 and Eddy Dissipation rate between multiple Doppler lidars, scintillometer and TLS are compared and the relationship between refractive index structure parameter and turbulence is explored. The effect of optical turbulence under various atmospheric conditions in complex terrain will be investigated.

Continuous scanning of the mobility and size distribution of charged clusters and nanometer particles in atmospheric air and the Balanced Scanning Mobility Analyzer BSMA

NASA Astrophysics Data System (ADS)

Tammet, H.

2006-12-01

Measuring of charged nanometer particles in atmospheric air is a routine task in research on atmospheric electricity, where these particles are called the atmospheric ions. An aspiration condenser is the most popular instrument for measuring atmospheric ions. Continuous scanning of a mobility distribution is possible when the aspiration condenser is connected as an arm of a balanced bridge. Transfer function of an aspiration condenser is calculated according to the measurements of geometric dimensions, air flow rate, driving voltage, and electric current. The most complicated phase of the calibration is the estimation of the inlet loss of ions due to the Brownian deposition. The available models of ion deposition on the protective inlet screen and the inlet control electrofilter have the uncertainty of about 20%. To keep the uncertainty of measurements low the adsorption should not exceed a few tens of percent. The online conversion of the mobility distribution to the size distribution and a correct reduction of inlet losses are possible when air temperature and pressure are measured simultaneously with the mobility distribution. Two instruments called the Balanced Scanning Mobility Analyzers (BSMA) were manufactured and tested in routine atmospheric measurements. The concentration of atmospheric ions of the size of about a few nanometers is very low and a high air flow rate is required to collect enough of ion current. The air flow of 52 l/s exceeds the air flow in usual aerosol instruments by 2-3 orders of magnitude. The high flow rate reduces the time of ion passage to 60 ms and the heating of air in an analyzer to 0.2 K, which suppresses a possible transformation of ions inside the instrument. The mobility range of the BSMA of 0.032-3.2 cm 2 V - 1 s - 1 is logarithmically uniformly divided into 16 fractions. The size distribution is presented by 12 fractions in the diameter range of 0.4-7.5 nm. The measurement noise of a fraction concentration is typically about 5 cm - 3 and the time resolution is about 10 min when measuring simultaneously both positive and negative ions in atmospheric air.

SU-E-CAMPUS-T-05: Validation of High-Resolution 3D Patient QA for Proton Pencil Beam Scanning and IMPT by Polymer Gel Dosimetry

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

Cardin, A; Avery, S; Ding, X

2014-06-15

Purpose: Validation of high-resolution 3D patient QA for proton pencil beam scanning and IMPT by polymer gel dosimetry. Methods: Four BANG3Pro polymer gel dosimeters (manufactured by MGS Research Inc, Madison, CT) were used for patient QA at the Robert's Proton Therapy Center (RPTC, Philadelphia, PA). All dosimeters were sealed in identical thin-wall Pyrex glass spheres. Each dosimeter contained a set of markers for 3D registration purposes. The dosimeters were mounted in a consistent and reproducible manner using a custom build holder. Two proton pencil beam scanning plans were designed using Varian Eclipse™ treatment planning system: 1) A two-field intensity modulatedmore » proton therapy (IMPT) plan and 2) one single field uniform dose (SFUD) plan. The IMPT fields were evaluated as a composite plan and individual fields, the SFUD plan was delivered as a single field plan.Laser CT scanning was performed using the manufacturer's OCTOPUS-IQ axial transmission laser CT scanner using a 1 mm slice thickness. 3D registration, analysis, and OD/cm to absorbed dose calibrations were perfomed using DICOM RT-Dose and CT files, and software developed by the manufacturer. 3D delta index, a metric equivalent to the gamma tool, was used for dose comparison. Results: Very good agreement with single IMPT fields and with SFUD was obtained. Composite IMPT fields had a less satisfactory agreement. The single fields had 3D delta index passing rates (3% dose difference, 3 mm DTA) of 98.98% and 94.91%. The composite 3D delta index passing rate was 80.80%. The SFUD passing rate was 93.77%. Required shifts of the dose distributions were less than 4 mm. Conclusion: A formulation of the BANG3Pro polymer gel dosimeter, suitable for 3D QA of proton patient plans is established and validated. Likewise, the mailed QA analysis service provided by the manufacturer is a practical option when required resources are unavailable. We fully disclose that the subject of this research regards a production of MGS Research, Inc.« less

Thermodynamics of mercaptopurine dehydration.

PubMed

Niazi, S

1978-04-01

The hydrate form of mercaptopurine was shown to undergo peritectic decomposition of its water molecule, localized dissolution, and dehydration around 125 degrees. The anhydrate form was prepared by a thermal method, whose effectiveness was confirmed by X-ray diffraction, NMR spectroscopy, and differential scanning calorimetry. The activation energy for mercaptopurine dehydration calculated by various methods ranged from 45.74 to 63.04 kcal/mole. The dehydration enthalpy was calculated to be 8.27 kcal/mole by differential scanning calorimetry. The solution enthalpy for the hydrate was calculated to be 4.85 kcal/mole from its saturation solubility and differential scanning calorimetry. Anhydrate solubility in water was calculated based on initial dissolution rate data since the anhydrate converts to hydrate in aqueous media. The high degree of stability against interconversion of the hydrate and anhydrate forms and the higher solubility of the anhydrate suggest that use of the anhydrate might improve mercaptopurine bioavailability.

Strategies to improve phase-stability of ultrafast swept source optical coherence tomography for single shot imaging of transient mechanical waves at 16 kHz frame rate

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

Song, Shaozhen; Wei, Wei; Hsieh, Bao-Yu

We present single-shot phase-sensitive imaging of propagating mechanical waves within tissue, enabled by an ultrafast optical coherence tomography (OCT) system powered by a 1.628 MHz Fourier domain mode-locked (FDML) swept laser source. We propose a practical strategy for phase-sensitive measurement by comparing the phases between adjacent OCT B-scans, where the B-scan contains a number of A-scans equaling an integer number of FDML buffers. With this approach, we show that micro-strain fields can be mapped with ∼3.0 nm sensitivity at ∼16 000 fps. The system's capabilities are demonstrated on porcine cornea by imaging mechanical wave propagation launched by a pulsed UV laser beam, promisingmore » non-contact, real-time, and high-resolution optical coherence elastography.« less

Preparation of Advanced Carbon Anode Materials from Mesocarbon Microbeads for Use in High C-Rate Lithium Ion Batteries

PubMed Central

Fang, Ming-Dar; Ho, Tsung-Han; Yen, Jui-Pin; Lin, Yu-Run; Hong, Jin-Long; Wu, She-Huang; Jow, Jiin-Jiang

2015-01-01

Mesophase soft carbon (MSC) and mesophase graphite (SMG), for use in comparative studies of high C-rate Lithium Ion Battery (LIB) anodes, were made by heating mesocarbon microbeads (MCMB) at 1300 °C and 3000 °C; respectively. The crystalline structures and morphologies of the MSC, SMG, and commercial hard carbon (HC) were investigated by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. Additionally, their electrochemical properties, when used as anode materials in LIBs, were also investigated. The results show that MSC has a superior charging rate capability compared to SMG and HC. This is attributed to MSC having a more extensive interlayer spacing than SMG, and a greater number of favorably-oriented pathways when compared to HC.

Evaluation of the influence of acquisition and reconstruction parameters for 16-row multidetector CT on coronary calcium scoring using a stationary and dynamic cardiac phantom.

PubMed

Begemann, Philipp G C; van Stevendaal, Udo; Koester, Ralph; Mahnken, Andreas H; Koops, Andreas; Adam, Gerhard; Grass, Michael; Nolte-Ernsting, Claus

2007-08-01

A calcium-scoring phantom with hydroxyapatite-filled cylindrical holes (0.5 to 4 mm) was used. High-resolution scans were performed for an accuracy baseline. The phantom was mounted to a moving heart phantom. Non-moving data with the implementation of an ECG-signal were acquired for different pitches (0.2/0.3), heart rates (60/80/95 bpm) and collimations (16 x 0.75/16 x 1.5 mm). Images were reconstructed with a cone-beam multi-cycle algorithm at a standard thickness/increment of 3 mm/1.5 mm and the thinnest possible thickness (0.8/0.4 and 2/1). Subsequently, ECG-gated moving calcium-scoring phantom data were acquired. The calcium volume and Agatston score were measured. The temporal resolution and reconstruction cycles were calculated. High-resolution scans determine the calcium volume with a high accuracy (mean overestimation, 0.8%). In the non-moving measurements, the volume underestimation ranged from about 6% (16 x 0.75 mm; 0.8/0.4 mm) to nearly 25% (16 x 1.5 mm; 3/1.5 mm). Moving scans showed increased measurement errors depending on the reconstructed RR interval, collimation, pitch, heart rate and gantry rotation time. Also, a correlation with the temporal resolution could be found. The reliability of calcium-scoring results can be improved with the use of a narrower collimation, a lower pitch and the reconstruction of thinner images, resulting in higher patient doses. The choice of the correct cardiac phase within the RR interval is essential to minimize measurement errors.

Capturing and modelling high-complex alluvial topography with UAS-borne laser scanning

NASA Astrophysics Data System (ADS)

Mandlburger, Gottfried; Wieser, Martin; Pfennigbauer, Martin

2015-04-01

Due to fluvial activity alluvial forests are zones of highest complexity and relief energy. Alluvial forests are dominated by new and pristine channels in consequence of current and historic flood events. Apart from topographic features, the vegetation structure is typically very complex featuring, both, dense under story as well as high trees. Furthermore, deadwood and debris carried from upstream during periods of high discharge within the river channel are deposited in these areas. Therefore, precise modelling of the micro relief of alluvial forests using standard tools like Airborne Laser Scanning (ALS) is hardly feasible. Terrestrial Laser Scanning (TLS), in turn, is very time consuming for capturing larger areas as many scan positions are necessary for obtaining complete coverage due to view occlusions in the forest. In the recent past, the technological development of Unmanned Arial Systems (UAS) has reached a level that light-weight survey-grade laser scanners can be operated from these platforms. For capturing alluvial topography this could bridge the gap between ALS and TLS in terms of providing a very detailed description of the topography and the vegetation structure due to the achievable very high point density of >100 points per m2. In our contribution we demonstrate the feasibility to apply UAS-borne laser scanning for capturing and modelling the complex topography of the study area Neubacher Au, an alluvial forest at the pre-alpine River Pielach (Lower Austria). The area was captured with Riegl's VUX-1 compact time-of-flight laser scanner mounted on a RiCopter (X-8 array octocopter). The scanner features an effective scan rate of 500 kHz and was flown in 50-100 m above ground. At this flying height the laser footprint is 25-50 mm allowing mapping of very small surface details. Furthermore, online waveform processing of the backscattered laser energy enables the retrieval of multiple targets for single laser shots resulting in a dense point cloud of, both, the ground surface and the alluvial vegetation. From the acquired point cloud the following products could be derived: (i) a very high resolution Digital Terrain Model (10 cm raster), (ii) a high resolution model of the water surface of the River Pielach (especially useful for validation of topo-bathymetry LiDAR data) and (iii) a detailed description of the complex vegetation structure.

Toward endoscopes with no distal optics: video-rate scanning microscopy through a fiber bundle.

PubMed

Andresen, Esben Ravn; Bouwmans, Géraud; Monneret, Serge; Rigneault, Hervé

2013-03-01

We report a step toward scanning endomicroscopy without distal optics. The focusing of the beam at the distal end of a fiber bundle is achieved by imposing a parabolic phase profile across the exit face with the aid of a spatial light modulator. We achieve video-rate images by galvanometric scanning of the phase tilt at the proximal end. The approach is made possible by the bundle, designed to have very low coupling between cores.

Development of Resistive Micromegas for Sampling Calorimetry

NASA Astrophysics Data System (ADS)

Geralis, T.; Fanourakis, G.; Kalamaris, A.; Nikas, D.; Psallidas, A.; Chefdeville, M.; Karyotakis, I.; Koletsou, I.; Titov, M.

2018-02-01

Resistive micromegas is proposed as an active element for sampling calorimetry. Future linear collider experiments or the HL-LHC experiments can profit from those developments for Particle Flow Calorimetry. Micromegas possesses remarkable properties concerning gain stability, reduced ion feedback, response linearity, adaptable sensitive element granularity, fast response and high rate capability. Recent developments on Micromegas with a protective resistive layer present excellent results, resolving the problem of discharges caused by local high charge deposition, thanks to its RC-slowed charge evacuation. Higher resistivity though, may cause loss of the response linearity at high rates. We have scanned a wide range of resistivities and performed laboratory tests with X-rays that demonstrate excellent response linearity up to rates of (a few) times 10MHz/cm2, with simultaneous mitigation of discharges. Beam test studies at SPS/CERN with hadrons have also shown a remarkable stability of the resistive Micromegas and low currents for rates up to 15MHz/cm2. We present results from the aforementioned studies confronted with MC simulation

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

Rubinstein, A; Kingsley, C; Melancon, A

Purpose: To evaluate the use of post-irradiation changes in respiratory rate and CBCT-based morphology as predictors of survival in mice. Methods: C57L/J mice underwent whole-thorax irradiation with a Co-60 beam to four different doses [0Gy (n=3), 9Gy (n=5), 11Gy (n=7), and 13Gy (n=5)] in order to induce varying levels of pneumonitis. Respiratory rate measurements, breath-hold CBCTs, and free-breathing CBCTs were acquired pre-irradiation and at six time points between two and seven months post-irradiation. For respiratory rate measurements, we developed a novel computer-vision-based technique. We recorded mice sleeping in standard laboratory cages with a 30 fps, 1080p webcam (Logitech C920). Wemore » calculated respiratory rate using corner detection and optical flow to track cyclical motion in the fur in the recorded video. Breath-hold and free-breathing CBCTs were acquired on the X-RAD225Cx system. For breathhold imaging, the mice were intubated and their breath was held at full-inhale for 20 seconds. Healthy lung tissue was delineated in the scans using auto-threshold contouring (0–0.7 g/cm{sup 3}). The volume of healthy lung was measured in each of the scans. Next, lung density was measured in a 6-mm{sup 2} ROI in a fixed anatomic location in each of the scans. Results: Day-to-day variability in respiratory rate with our technique was 13%. All metrics except for breath-hold lung volume were correlated with survival: lung density on free-breathing (r=−0.7482,p<0.01) and breath-hold images (r=−0.5864,p<0.01), free-breathing lung volume (r=0.7179,p<0.01), and respiratory rate (r= 0.6953,p<0.01). Lung density on free-breathing scans was correlated with respiratory rate (r=0.7142,p<0.01) and lung density on breath-hold scans (r=0.5543,p<0.01). One significant practical hurdle in the CBCT measurements was that at least one lobe of the lung was collapsed in 36% of free-breathing scans and 45% of breath-hold scans. Conclusion: Lung density and lung volume on free-breathing CBCTs and respiratory rate outperform breath-hold CBCT measurements as indicators for survival from radiation-induced pneumonitis. This work was partially funded by Elekta.« less

Effect of the scanning speed on microstructural evolution and wear behaviors of laser cladding NiCrBSi composite coatings

NASA Astrophysics Data System (ADS)

Chen, J. L.; Li, J.; Song, R.; Bai, L. L.; Shao, J. Z.; Qu, C. C.

2015-09-01

Laser cladding composite coatings were fabricated on the surface of the Ti6Al4V substrate by fiber laser cladding the NiCrBSi alloy powder. The influences of scanning speed on the dilution rate and microstructure of the coatings were investigated in detail by X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS). Combined with the analyses of microhardness and fracture toughness, the wear behaviors of the coatings obtained at different scanning speeds were revealed. Results indicated that the dilution rates of the coatings were similar (about 64.23%) with variations in scanning speed ranging from 5 mm/s to 15 mm/s. An abrupt decrease in dilution rate (37.06%) was observed at the scanning speed of 20 mm/s. Microstructural observation showed that the blocky TiB2 and the cellular dendrite TiC particles were uniformly dispersed in the TiNi-Ti2Ni dual-phase intermetallic compound matrix at scanning speeds of 5-15 mm/s. When the scanning speed was further increased to 20 mm/s, the stripe-shaped CrB, gray irregular-shaped Cr3C2 and black blocky TiC particles uniformly dispersed in the γ(Ni) matrix were synthesized in situ. The particles became finer with the increase in scanning speed. The average microhardness of the coating (1026.5 HV0.2) at the scanning speed of 20 mm/s was enhanced significantly compared with that of the other three coatings (about 886.4 HV0.2). The lowest average friction coefficient (about 0.371) was obtained at the scanning speed of 20 mm/s and was relatively stable with the change in sliding time. The lowest wear loss of the coating was also obtained at the scanning speed of 20 mm/s. Analyses of the worn surfaces showed that the coating prepared at the scanning speed of 20 mm/s was in good condition because of its excellent combination of resistance to micro-cutting and brittle debonding. Comparatively speaking, the coating produced at the scanning speed of 20 mm/s possessed excellent comprehensive mechanical properties.

Large volume serial section tomography by Xe Plasma FIB dual beam microscopy.

PubMed

Burnett, T L; Kelley, R; Winiarski, B; Contreras, L; Daly, M; Gholinia, A; Burke, M G; Withers, P J

2016-02-01

Ga(+) Focused Ion Beam-Scanning Electron Microscopes (FIB-SEM) have revolutionised the level of microstructural information that can be recovered in 3D by block face serial section tomography (SST), as well as enabling the site-specific removal of smaller regions for subsequent transmission electron microscope (TEM) examination. However, Ga(+) FIB material removal rates limit the volumes and depths that can be probed to dimensions in the tens of microns range. Emerging Xe(+) Plasma Focused Ion Beam-Scanning Electron Microscope (PFIB-SEM) systems promise faster removal rates. Here we examine the potential of the method for large volume serial section tomography as applied to bainitic steel and WC-Co hard metals. Our studies demonstrate that with careful control of milling parameters precise automated serial sectioning can be achieved with low levels of milling artefacts at removal rates some 60× faster. Volumes that are hundreds of microns in dimension have been collected using fully automated SST routines in feasible timescales (<24h) showing good grain orientation contrast and capturing microstructural features at the tens of nanometres to the tens of microns scale. Accompanying electron back scattered diffraction (EBSD) maps show high indexing rates suggesting low levels of surface damage. Further, under high current Ga(+) FIB milling WC-Co is prone to amorphisation of WC surface layers and phase transformation of the Co phase, neither of which have been observed at PFIB currents as high as 60nA at 30kV. Xe(+) PFIB dual beam microscopes promise to radically extend our capability for 3D tomography, 3D EDX, 3D EBSD as well as correlative tomography. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

Imaging in the newborn: infant immobilizer obviates the need for anesthesia.

PubMed

Golan, Agneta; Marco, Rina; Raz, Hagit; Shany, Eilon

2011-11-01

Neonatal cerebral imaging is a sensitive technique for evaluating brain injury in the neonatal period. When performing computed tomography or magnetic resonance imaging, sedation is needed to prevent motion artifacts. However, general anesthesia in neonates carries significant risks and requires a complex logistic approach that often limits the use of these modalities. The development of infant immobilizers now enables imaging without general anesthesia and significantly increases clinical and research investigational opportunities. To assess the efficacy of the infant immobilizer instead of general anesthesia for infants undergoing imaging. The study group comprised all infants born over a 1 year period at Soroka University Medical Center who required imaging such as MRI, CT or bone scans. A MedVac Vacuum Splint infant immobilizer was used in all infants to prevent motion during imaging. The success rate of a single scan and the need for general anesthesia were assessed. Forty infants were examined during 1 year. The studies included 15 CT scans, 25 MRIs and 1 bone scan. The infants' gestational age at birth was 27-40 weeks and the examinations were performed at ages ranging from delivery to 6 months old. All imaging was successful and none of the infants required general anesthesia. An infant immobilizer should be used for imaging of newborns. Since this method carries a low risk and has a high success rate, general anesthesia in newborns is justified only when this non-invasive procedure fails.

Evaluating causes of error in landmark-based data collection using scanners

PubMed Central

Shearer, Brian M.; Cooke, Siobhán B.; Halenar, Lauren B.; Reber, Samantha L.; Plummer, Jeannette E.; Delson, Eric

2017-01-01

In this study, we assess the precision, accuracy, and repeatability of craniodental landmarks (Types I, II, and III, plus curves of semilandmarks) on a single macaque cranium digitally reconstructed with three different surface scanners and a microCT scanner. Nine researchers with varying degrees of osteological and geometric morphometric knowledge landmarked ten iterations of each scan (40 total) to test the effects of scan quality, researcher experience, and landmark type on levels of intra- and interobserver error. Two researchers additionally landmarked ten specimens from seven different macaque species using the same landmark protocol to test the effects of the previously listed variables relative to species-level morphological differences (i.e., observer variance versus real biological variance). Error rates within and among researchers by scan type were calculated to determine whether or not data collected by different individuals or on different digitally rendered crania are consistent enough to be used in a single dataset. Results indicate that scan type does not impact rate of intra- or interobserver error. Interobserver error is far greater than intraobserver error among all individuals, and is similar in variance to that found among different macaque species. Additionally, experience with osteology and morphometrics both positively contribute to precision in multiple landmarking sessions, even where less experienced researchers have been trained in point acquisition. Individual training increases precision (although not necessarily accuracy), and is highly recommended in any situation where multiple researchers will be collecting data for a single project. PMID:29099867

The measurements of water flow rates in the straight microchannel based on the scanning micro-PIV technique

NASA Astrophysics Data System (ADS)

Wang, H. L.; Han, W.; Xu, M.

2011-12-01

Measurement of the water flow rate in microchannel has been one of the hottest points in the applications of microfluidics, medical, biological, chemical analyses and so on. In this study, the scanning microscale particle image velocimetry (scanning micro-PIV) technique is used for the measurements of water flow rates in a straight microchannel of 200μm width and 60μm depth under the standard flow rates ranging from 2.481μL/min to 8.269μL/min. The main effort of this measurement technique is to obtain three-dimensional velocity distribution on the cross sections of microchannel by measuring velocities of the different fluid layers along the out-of-plane direction in the microchannel, so the water flow rates can be evaluated from the discrete surface integral of velocities on the cross section. At the same time, the three-dimensional velocity fields in the measured microchannel are simulated numerically using the FLUENT software in order to verify the velocity accuracy of measurement results. The results show that the experimental values of flow rates are well consistent to the standard flow rates input by the syringe pump and the compared results between numerical simulation and experiment are consistent fundamentally. This study indicates that the micro-flow rate evaluated from three-dimensional velocity by the scanning micro-PIV technique is a promising method for the micro-flow rate research.

Mass loss in red giants and supergiants

NASA Technical Reports Server (NTRS)

Sanner, F.

1975-01-01

The circumstellar envelopes surrounding late-type giants and supergiants were studied using high resolution, photoelectric scans of strong optical resonance lines. A method for extracting the circumstellar from the stellar components of the lines allowed a quantitative determination of the physical conditions in the envelopes and the rates of mass loss at various positions in the red giant region of the HR diagram. The observed strengthening of the circumstellar spectrum with increasing luminosity and later spectral type is probably caused by an increase in the mass of the envelopes. The mass loss rate for individual stars is proportional to the visual luminosity; high rates for the supergiants suggest that mass loss is important in their evolution. The bulk of the mass return to the interstellar medium in the red giant region comes from the normal giants, at a rate comparable to that of planetary nebulae.

Monte Carlo simulation of Ray-Scan 64 PET system and performance evaluation using GATE toolkit

NASA Astrophysics Data System (ADS)

Li, Suying; Zhang, Qiushi; Vuletic, Ivan; Xie, Zhaoheng; Yang, Kun; Ren, Qiushi

2017-02-01

In this study, we aimed to develop a GATE model for the simulation of Ray-Scan 64 PET scanner and model its performance characteristics. A detailed implementation of system geometry and physical process were included in the simulation model. Then we modeled the performance characteristics of Ray-Scan 64 PET system for the first time, based on National Electrical Manufacturers Association (NEMA) NU-2 2007 protocols and validated the model against experimental measurement, including spatial resolution, sensitivity, counting rates and noise equivalent count rate (NECR). Moreover, an accurate dead time module was investigated to simulate the counting rate performance. Overall results showed reasonable agreement between simulation and experimental data. The validation results showed the reliability and feasibility of the GATE model to evaluate major performance of Ray-Scan 64 PET system. It provided a useful tool for a wide range of research applications.

[The occurrence of Echinococcus multilocularis in red foxes in lower Saxony: identification of a high risk area by spatial epidemiological cluster analysis].

PubMed

Berke, Olaf; von Keyserlingk, Michael; Broll, Susanne; Kreienbrock, Lothar

2002-01-01

There is considerable interest in the spatial distribution of Echinococcus multilocularis in red foxes (Vulpes vulpes L.), because this parasite causes the zoonoses of alveolar echinococcosis which is potentially of high fatality rate. High risk areas are known from France, Switzerland and the Swabian Alb in Germany for a long time. In this work, the spatial scan statistic is introduced as an instrument for identification and localisation of high risk areas, so called disease clusters in spatial epidemiology. The use of the spatial scan statistic along with data about the distribution of the parasite in 5365 red foxes in Lower Saxony, that were collected during 1991 to 1997, led to the identification of another high risk area. The relative risk for this disease cluster is approximated by RR = 5.03 (CI0.95(RR) = [4.27; 6.58]) for the period of 1991 to 1994 and by RR = 4.45 (CI0.95(RR) = [3.53; 5.59]) for the period of 1994 to 1997, respectively.

Fabrication and Characterization of High Strength Al-Cu Alloys Processed Using Laser Beam Melting in Metal Powder Bed

NASA Astrophysics Data System (ADS)

Ahuja, Bhrigu; Karg, Michael; Nagulin, Konstantin Yu.; Schmidt, Michael

The proposed paper illustrates fabrication and characterization of high strength Aluminium Copper alloys processed using Laser Beam Melting process. Al-Cu alloys EN AW-2219 and EN AW-2618 are classified as wrought alloys and 2618 is typically considered difficult to weld. Laser Beam Melting (LBM) process from the family of Additive Manufacturing processes, has the unique ability to form fully dense complex 3D geometries using micro sized metallic powder in a layer by layer fabrication methodology. LBM process can most closely be associated to the conventional laser welding process, but has significant differences in terms of the typical laser intensities and scan speeds used. Due to the use of high intensities and fast scan speeds, the process induces extremely high heating and cooling rates. This property gives it a unique physical attribute and therefore its ability to process high strength Al-Cu alloys needs to be investigated. Experiments conducted during the investigations associate the induced energy density controlled by varying process parameters to the achieved relative densities of the fabricated 3D structures.

High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

PubMed

Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

2016-02-01

We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams.

Analysis of SFMR-Derived and Satellite-Based Rain Rates over the Tropical Western North Pacific

DTIC Science & Technology

2010-03-01

from SFMR are compared to rain rates from the Advanced Microwave Scanning Radiometer–EOS ( ASMR -E) and the Tropical Rainfall Measuring Mission (TRMM...2010 program. Rain rates from SFMR are compared to rain rates from the Advanced Microwave Scanning Radiometer–EOS ( ASMR -E) and the Tropical Rainfall...Figures 10 and 11, except for the ASMR -E and (a) earth-relative flight track and (b) storm-relative flight track for TY Sinlaku on 12 Sep 2008

Scalable wide-field optical coherence tomography-based angiography for in vivo imaging applications

PubMed Central

Xu, Jingjiang; Wei, Wei; Song, Shaozhen; Qi, Xiaoli; Wang, Ruikang K.

2016-01-01

Recent advances in optical coherence tomography (OCT)-based angiography have demonstrated a variety of biomedical applications in the diagnosis and therapeutic monitoring of diseases with vascular involvement. While promising, its imaging field of view (FOV) is however still limited (typically less than 9 mm2), which somehow slows down its clinical acceptance. In this paper, we report a high-speed spectral-domain OCT operating at 1310 nm to enable wide FOV up to 750 mm2. Using optical microangiography (OMAG) algorithm, we are able to map vascular networks within living biological tissues. Thanks to 2,048 pixel-array line scan InGaAs camera operating at 147 kHz scan rate, the system delivers a ranging depth of ~7.5 mm and provides wide-field OCT-based angiography at a single data acquisition. We implement two imaging modes (i.e., wide-field mode and high-resolution mode) in the OCT system, which gives highly scalable FOV with flexible lateral resolution. We demonstrate scalable wide-field vascular imaging for multiple finger nail beds in human and whole brain in mice with skull left intact at a single 3D scan, promising new opportunities for wide-field OCT-based angiography for many clinical applications. PMID:27231630

Conflicts between sensory performance and locomotion in weakly electric fish

NASA Astrophysics Data System (ADS)

Maciver, Malcolm; Shirgaonkar, Anup; Patankar, Neelesh

2008-11-01

The knifefish Apteronotus albifrons hunts for small water insects at night using a self-generated electric field to perceive its world. Using this unique sensory adaptation, the fish senses prey that are near its body with a detection volume that approximates a cylinder that has a length ten times its radius, similar to the fish's elongated body plan. If the fish swims straight, then the back portion of the actively generated detection volume is scanning fluid already scanned by the front portion, but the energy expended to overcome drag is minimized. If it swims with the body pitched, then the rate of volume scanned for prey is increased, but the energy needed to overcome body drag is also increased. In this work we examine the compromise the fish makes between minimizing energy in overcoming drag and maximizing scan rate. We use computational fluid dynamics simulations to assess the impact of changes in body pitch angle on drag, and computational neuroscience simulations to assess the shape and size of the prey detection volume and how body angle changes the scan volume rate.

The impact of antemortem computed tomographic scanning on postmortem examination rate and frequency of missed diagnosis: A retrospective analysis of postmortem examination data.

PubMed

Liisanantti, Janne Henrik; Ala-Kokko, Tero Ilmari

2015-12-01

The present study was conducted to explore the impact of computed tomographic (CT) scanning on the diagnostic discrepancy rate. This single-center, retrospective study reviewed postmortem examination results, clinical diagnoses, and radiologic imaging data for patients admitted to the intensive care unit (ICU) in 2008 to 2013. The Goldman criteria were used to classify diagnostic discrepancies. The data of 577 patients who died during their ICU stay were retrieved. The postmortem examination rate was 42.9% (n=248). Significant diagnostic discrepancies (Goldman I and II) were recorded in 24 cases (9.7%). The postmortem examination rate decreased significantly from the first half (n=143; 51.1%) to the second half (n=105; 35.4%) of the study period (P<.0001). Among those with postmortem examinations, the use of antemortem body CT scans increased significantly from the first half (n=59; 41.3%) to the second half (n=64; 51.0%; P=.002) of the study period. The significant diagnostic discrepancy rate did not change with time (8.4% vs 11.4%, respectively; P=.424). The postmortem examination rate has decreased, whereas antemortem CT scans has increased. Copyright © 2015 Elsevier Inc. All rights reserved.

Video-rate scanning two-photon excitation fluorescence microscopy and ratio imaging with cameleons.

PubMed Central

Fan, G Y; Fujisaki, H; Miyawaki, A; Tsay, R K; Tsien, R Y; Ellisman, M H

1999-01-01

A video-rate (30 frames/s) scanning two-photon excitation microscope has been successfully tested. The microscope, based on a Nikon RCM 8000, incorporates a femtosecond pulsed laser with wavelength tunable from 690 to 1050 nm, prechirper optics for laser pulse-width compression, resonant galvanometer for video-rate point scanning, and a pair of nonconfocal detectors for fast emission ratioing. An increase in fluorescent emission of 1.75-fold is consistently obtained with the use of the prechirper optics. The nonconfocal detectors provide another 2.25-fold increase in detection efficiency. Ratio imaging and optical sectioning can therefore be performed more efficiently without confocal optics. Faster frame rates, at 60, 120, and 240 frames/s, can be achieved with proportionally reduced scan lines per frame. Useful two-photon images can be acquired at video rate with a laser power as low as 2.7 mW at specimen with the genetically modified green fluorescent proteins. Preliminary results obtained using this system confirm that the yellow "cameleons" exhibit similar optical properties as under one-photon excitation conditions. Dynamic two-photon images of cardiac myocytes and ratio images of yellow cameleon-2.1, -3.1, and -3.1nu are also presented. PMID:10233058

Increasing Children’s Physical Activity During School Recess Periods

PubMed Central

Ludwig, David

2013-01-01

Objectives. We examined whether schools’ participation in the Recess Enhancement Program (REP) in the spring of 2011 was associated with higher rates of children’s vigorous physical activity. Methods. In REP, a coach guides children through age-appropriate games aimed at increasing their physical activity. During recess at 25 New York City public elementary schools (15 REP, 10 non-REP), researchers visually scanned predetermined areas (n = 1339 scans), recording the number of sedentary, walking, and very active children. Results. Multivariate statistical analysis found that participation in REP was a significant predictor (P = .027) of the rate of vigorous physical activity (percentage very active in scan area) whose least-squares means were 41% in REP schools and 27% in non-REP schools. A significantly higher rate in REP schools persisted when the coach was not in the scan area, suggesting a change in the recess culture of REP schools. Conclusions. The rate of vigorous physical activity in REP schools was 14 percentage points, or 52%, higher than the rate in non-REP schools. This low-cost intervention might be a valuable addition to the tools for combating childhood obesity and worth replicating elsewhere. PMID:23678902

A simple rule for the costs of vigilance: empirical evidence from a social forager.

PubMed Central

Cowlishaw, Guy; Lawes, Michael J.; Lightbody, Margaret; Martin, Alison; Pettifor, Richard; Rowcliffe, J. Marcus

2004-01-01

It is commonly assumed that anti-predator vigilance by foraging animals is costly because it interrupts food searching and handling time, leading to a reduction in feeding rate. When food handling does not require visual attention, however, a forager may handle food while simultaneously searching for the next food item or scanning for predators. We present a simple model of this process, showing that when the length of such compatible handling time Hc is long relative to search time S, specifically Hc/S > 1, it is possible to perform vigilance without a reduction in feeding rate. We test three predictions of this model regarding the relationships between feeding rate, vigilance and the Hc/S ratio, with data collected from a wild population of social foragers (samango monkeys, Cercopithecus mitis erythrarchus). These analyses consistently support our model, including our key prediction: as Hc/S increases, the negative relationship between feeding rate and the proportion of time spent scanning becomes progressively shallower. This pattern is more strongly driven by changes in median scan duration than scan frequency. Our study thus provides a simple rule that describes the extent to which vigilance can be expected to incur a feeding rate cost. PMID:15002768

Atomic-scale imaging of DNA using scanning tunnelling microscopy.

PubMed

Driscoll, R J; Youngquist, M G; Baldeschwieler, J D

1990-07-19

The scanning tunnelling microscope (STM) has been used to visualize DNA under water, under oil and in air. Images of single-stranded DNA have shown that submolecular resolution is possible. Here we describe atomic-resolution imaging of duplex DNA. Topographic STM images of uncoated duplex DNA on a graphite substrate obtained in ultra-high vacuum are presented that show double-helical structure, base pairs, and atomic-scale substructure. Experimental STM profiles show excellent correlation with atomic contours of the van der Waals surface of A-form DNA derived from X-ray crystallography. A comparison of variations in the barrier to quantum mechanical tunnelling (barrier-height) with atomic-scale topography shows correlation over the phosphate-sugar backbone but anticorrelation over the base pairs. This relationship may be due to the different chemical characteristics of parts of the molecule. Further investigation of this phenomenon should lead to a better understanding of the physics of imaging adsorbates with the STM and may prove useful in sequencing DNA. The improved resolution compared with previously published STM images of DNA may be attributable to ultra-high vacuum, high data-pixel density, slow scan rate, a fortuitously clean and sharp tip and/or a relatively dilute and extremely clean sample solution. This work demonstrates the potential of the STM for characterization of large biomolecular structures, but additional development will be required to make such high resolution imaging of DNA and other large molecules routine.

The use of a fully integrated electronic medical record to minimize cumulative lifetime radiation exposure from CT scanning to detect urinary tract calculi.

PubMed

Kohler, Steven W; Chen, Richard; Kagan, Alex; Helvey, Dustin W; Buccigrossi, David

2013-06-01

In order to determine the effects of implementation of an electronic medical record on rates of repeat computed tomography (CT) scanning in the emergency department (ED) setting, we analyzed the utilization of CT of the kidneys, ureters, and bladder (CT KUB) for the detection of urinary tract calculi for periods before and after the implementation of a hospital-wide electronic medical record system. Rates of repeat CT scanning within a 6-month period of previous scan were determined pre- and post-implementation and compared. Prior to implementation, there was a 6-month repeat rate of 6.2 % compared with the post-implementation period, which was associated with a 6-month repeat rate of 4.1 %. Statistical analysis using a two-sample, one-tailed t test for difference of means was associated with a p value of 0.00007. This indicates that the implementation of the electronic medical record system was associated with a 34 % decrease in 6-month repeat CT KUB scans. We conclude that the use of an electronic medical record can be associated with a decrease in utilization of unnecessary repeat CT imaging, leading to decreased cumulative lifetime risk for cancer in these patients and more efficient utilization of ED and radiologic resources.

Probing Intermolecular Interactions in Binary Liquid Mixtures Using Femtosecond Laser-Induced Self-Defocusing.

PubMed

Maurya, Sandeep Kumar; Das, Dhiman; Goswami, Debabrata

2016-06-13

Photo-thermal behavior of binary liquid mixtures has been studied by high repetition rate (HRR) Z-scan technique with femtosecond laser pulses. Changes in the peak-valley difference in transmittance (ΔT P-V ) for closed aperture Z-scan experiments are indicative of thermal effects induced by HRR femtosecond laser pulses. We show such indicative results can have a far-reaching impact on molecular properties and intermolecular interactions in binary liquid mixtures. Spectroscopic parameters derived from this experimental technique show that the combined effect of physical and molecular properties of the constituent binary liquids can be related to the components of the binary liquid. © The Author(s) 2016.

Optical shielding of nickel nanoparticle by a bubble: Optical limiting gets limited

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

Shukla, Vijay; Jayabalan, J., E-mail: jjaya@rrcat.gov.in; Chari, Rama

2016-06-13

We have demonstrated that in a nickel nanoparticle colloid, the optical limiting action reduces if a vapor bubble forms around the nanoparticle. The energy-dependent transmission and z-scan measurements on nickel nanoparticles in toluene show the onset of an additional process. At high fluence excitation, the particle becomes less visible to the later part of the incoming pulse due to the heat generated bubble formed around it. We have proposed a simple “particle-in-bubble” model which fits the optical limiting and z-scan curves quite well. Using this model, we have also estimated that the bubble radius increases at a rate of 4.5 m/s.

Pseudocapacitive Electrodes Produced by Oxidant-Free Polymerization of Pyrrole between the Layers of 2D Titanium Carbide (MXene)

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

Boota, Muhammad; Anasori, Babak; Voigt, Cooper

Heterocyclic pyrrole molecules are in situ aligned and polymerized in the ­absence of an oxidant between layers of the 2D Ti3C2Tx (MXene), resulting in high volumetric and gravimetric capacitances with capacitance retention of 92% after 25 000 cycles at a 100 mV s-1 scan rate.

Evaluation of Pathogenicity of the Fungi Metarhizium anisopliae and Beauveria bassiana in Hazelnut Weevil (Curculio nucum L., Coleoptera, Curculionidae) Larvae.

PubMed

Cheng, Yunqing; Liu, Ting; Zhao, Yixin; Geng, Wanting; Chen, Longtao; Liu, Jianfeng

2016-12-01

The nut weevil ( Curculio nucum ) is one of the most important and widespread pests in hazelnut orchards. In order to screen entomopathogenic fungal strains with high virulence against C. nucum , the growth rate, sporulation, and cumulative mortality of different Metarhizium anisopliae and Beauveria bassiana strains were investigated, and the process by which M. anisopliae CoM 02 infects C. nucum larvae was observed using scanning electron microscopy. The results indicated that the growth rate and sporulation of different fungal strains significantly differed. Thirteen days after inoculation with M. anisopliae CoM 02, the cumulative mortality of C. nucum larvae reached 100 %, which was considerably higher than that of the other five strains. As the most virulent of the six test strains, the cadaver rate, LT 50 , and LT 90 of M. anisopliae CoM 02 were 93.4 %, 7.05 and 11.90 days, respectively. Analysis of the infection process by scanning electron microscopy showed that the spore attachment, hyphal germination, hyphal rapid growth, and sporulation of M. anisopliae CoM 02 occurred on the 3rd, 5th, 7th, and 11th day after inoculation, respectively, indicating that the infection cycle takes approximately 11 days. This finding suggests that the highly virulent M. anisopliae plays an important role in the biocontrol of C. nucum in China.

Application of a high-repetition-rate laser diagnostic system for single-cycle-resolved imaging in internal combustion engines.

PubMed

Hult, Johan; Richter, Mattias; Nygren, Jenny; Aldén, Marcus; Hultqvist, Anders; Christensen, Magnus; Johansson, Bengt

2002-08-20

High-repetition-rate laser-induced fluorescence measurements of fuel and OH concentrations in internal combustion engines are demonstrated. Series of as many as eight fluorescence images, with a temporal resolution ranging from 10 micros to 1 ms, are acquired within one engine cycle. A multiple-laser system in combination with a multiple-CCD camera is used for cycle-resolved imaging in spark-ignition, direct-injection stratified-charge, and homogeneous-charge compression-ignition engines. The recorded data reveal unique information on cycle-to-cycle variations in fuel transport and combustion. Moreover, the imaging system in combination with a scanning mirror is used to perform instantaneous three-dimensional fuel-concentration measurements.

Differential Multiphoton Laser Scanning Microscopy

PubMed Central

Field, Jeffrey J.; Sheetz, Kraig E.; Chandler, Eric V.; Hoover, Erich E.; Young, Michael D.; Ding, Shi-you; Sylvester, Anne W.; Kleinfeld, David; Squier, Jeff A.

2016-01-01

Multifocal multiphoton microscopy (MMM) in the biological and medical sciences has become an important tool for obtaining high resolution images at video rates. While current implementations of MMM achieve very high frame rates, they are limited in their applicability to essentially those biological samples that exhibit little or no scattering. In this paper, we report on a method for MMM in which imaging detection is not necessary (single element point detection is implemented), and is therefore fully compatible for use in imaging through scattering media. Further, we demonstrate that this method leads to a new type of MMM wherein it is possible to simultaneously obtain multiple images and view differences in excitation parameters in a single shot. PMID:27390511

Self-correcting electronically scanned pressure sensor

NASA Technical Reports Server (NTRS)

Gross, C. (Inventor)

1983-01-01

A multiple channel high data rate pressure sensing device is disclosed for use in wind tunnels, spacecraft, airborne, process control, automotive, etc., pressure measurements. Data rates in excess of 100,000 measurements per second are offered with inaccuracies from temperature shifts less than 0.25% (nominal) of full scale over a temperature span of 55 C. The device consists of thirty-two solid state sensors, signal multiplexing electronics to electronically address each sensor, and digital electronic circuitry to automatically correct the inherent thermal shift errors of the pressure sensors and their associated electronics.

Evaluation of a single-scan protocol for radiochromic film dosimetry.

PubMed

Shimohigashi, Yoshinobu; Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

2015-03-08

The purpose of this study was to evaluate a single-scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24-hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24-hr protocol). The single-scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single-scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity-modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single-scan protocol was within 2% of the 24-hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single-scan and 24-hr protocols were 2.0 ± 1.8 cGy and 1.4 ± 1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single-scan protocol and 95.9% for the 24-hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6 ± 3.5cGy and 2.9 ± 3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7% ± 1.8% for the single-scan protocol and 97.3% ± 1.4% for the 24-hr protocol. Thus, the single-scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency.

Evaluation of a single‐scan protocol for radiochromic film dosimetry

PubMed Central

Araki, Fujio; Maruyama, Masato; Nakaguchi, Yuji; Kuwahara, Satoshi; Nagasue, Nozomu; Kai, Yudai

2015-01-01

The purpose of this study was to evaluate a single‐scan protocol using Gafchromic EBT3 film (EBT3) by comparing it with the commonly used 24‐hr measurement protocol for radiochromic film dosimetry. Radiochromic film is generally scanned 24 hr after film exposure (24‐hr protocol). The single‐scan protocol enables measurement results within a short time using only the verification film, one calibration film, and unirradiated film. The single‐scan protocol was scanned 30 min after film irradiation. The EBT3 calibration curves were obtained with the multichannel film dosimetry method. The dose verifications for each protocol were performed with the step pattern, pyramid pattern, and clinical treatment plans for intensity‐modulated radiation therapy (IMRT). The absolute dose distributions for each protocol were compared with those calculated by the treatment planning system (TPS) using gamma evaluation at 3% and 3 mm. The dose distribution for the single‐scan protocol was within 2% of the 24‐hr protocol dose distribution. For the step pattern, the absolute dose discrepancies between the TPS for the single‐scan and 24‐hr protocols were 2.0±1.8 cGy and 1.4±1.2 cGy at the dose plateau, respectively. The pass rates were 96.0% for the single‐scan protocol and 95.9% for the 24‐hr protocol. Similarly, the dose discrepancies for the pyramid pattern were 3.6±3.5 cGy and 2.9±3.3 cGy, respectively, while the pass rates for the pyramid pattern were 95.3% and 96.4%, respectively. The average pass rates for the four IMRT plans were 96.7%±1.8% for the single‐scan protocol and 97.3%±1.4% for the 24‐hr protocol. Thus, the single‐scan protocol measurement is useful for dose verification of IMRT, based on its accuracy and efficiency. PACS number: 87.55.Qr PMID:26103194

Dynamics of Debris Supply and Removal from Coastal Cliffs

NASA Astrophysics Data System (ADS)

Dickson, M. E.; Vann Jones, E. C.; Payo, A.; Matsumoto, H.

2016-12-01

Progress in obtaining a morphodynamic understanding of rocky shores has been limited by slow rates of change and lack of preserved evidence of erosion processes. As a result we do not have a detailed understanding of the relative contributions of failure events across the magnitude-frequency spectrum. This talk describes field experiments, supported by simple stock-flow modelling, on a coastal cliff-face in eastern New Zealand. Key features of this site are that it is composed of near-homogenous rapidly eroding mudstone, and it is fronted by a wide intertidal rock platform that results in the cliff toe being exposed to waves every high tide. Several techniques were used to measure the cliff debris supply-removal system. Sediment traps at the cliff toe directly recorded rates of debris supply from the cliff-face at five discrete locations. Repeated high-resolution terrestrial laser scans over several consecutive low-tide stages documented changes in cliff-toe talus volumes along 50m of shoreline. Optical back-scatter sensors located on the rock shore platform in front of the cliff toe constrained the timing of talus-debris resuspension during tidal inundation of the cliff toe. Wave pressure gauges were used to characterise the wave field acting on the cliff. Results demonstrate that high-resolution (<5mm) laser scanning can meaningfully characterise rates of coastal cliff erosion at the very high-frequency low-magnitude end of the erosion spectrum. We find that rates of debris supply from the cliff face are dependent on the subaerial weathering system, in particular wetting and drying and associated expansion and contraction of clay minerals within the cliff rock. Rates of debris removal from the cliff toe depend on tide and wave conditions: even under low wave-energy conditions, waves at infragravity frequencies can access the cliff toe at high tide leading to sediment suspension. We explore the basic feedback structure of cliff, talus and debris removal using a simple stock-flow model, and discuss implications for progressive (ongoing) cliff erosion in the presence of an ever-widening shore platform.

Impact of Contrast Media Concentration on Low-Kilovolt Computed Tomography Angiography: A Systematic Preclinical Approach.

PubMed

Fleischmann, Ulrike; Pietsch, Hubertus; Korporaal, Johannes G; Flohr, Thomas G; Uder, Michael; Jost, Gregor; Lell, Michael M

2018-05-01

Low peak kilovoltage (kVp) protocols in computed tomography angiography (CTA) demand a review of contrast media (CM) administration practices. The aim of this study was to systematically evaluate different iodine concentrations of CM in a porcine model. Dynamic 70 kVp CTA was performed on 7 pigs using a third-generation dual-source CT system. Three CM injection protocols (A-C) with an identical total iodine dose and iodine delivery rate (150 mg I/kg, 12 s, 0.75 g I/s) differed in iodine concentration and flow rate (protocol A: 400 mg I/mL, 1.9 mL/s; B: 300 mg I/mL, 2.5 mL/s; C: 150 mg I/mL, 5 mL/s). All protocols were applied in a randomized order and compared intraindividually. Arterial enhancement at different locations in the pulmonary artery, the aorta, and aortic branches was measured over time. Time attenuation curves, peak enhancement, time to peak, and bolus tracking delay times needed for static CTA were calculated. The reproducibility of optimal parameters was tested in single-phase CTA. The heart rates of the pigs were comparable for all protocols (P > 0.7). The injection pressure was significantly higher for protocol A (64 ± 5 psi) and protocol C (55 ± 3 psi) compared with protocol B (39 ± 2 psi) (P < 0.001). Average arterial peak enhancement in the dynamic scans was 359 ± 51 HU (protocol A), 382 ± 36 HU (B), and 382 ± 60 HU (C) (A compared with B and C: P < 0.01; B compared with C: P = 0.995). Time to peak enhancement decreased with increasing injection rate. The delay time for bolus tracking depended on the injection rate as well and was highest for protocol A (4.7 seconds) and lowest for protocol C (3.9 seconds) (P = 0.038). The peak enhancement values of the dynamic scans highly correlated with those of the single-phase CTA scans. In 70 kVp CTA, 300 mg I/mL iodine concentrations showed to be superior to high-concentration CM when keeping the iodine delivery rate constant. Besides, iodine concentrations as low as 150 mg I/mL can be administered without compromising vascular enhancement. This opens up new possibilities in CM administration.

Compensation of temporal and spatial dispersion for multiphoton acousto-optic laser-scanning microscopy

NASA Astrophysics Data System (ADS)

Iyer, Vijay; Saggau, Peter

2003-10-01

In laser-scanning microscopy, acousto-optic (AO) deflection provides a means to quickly position a laser beam to random locations throughout the field-of-view. Compared to conventional laser-scanning using galvanometer-driven mirrors, this approach increases the frame rate and signal-to-noise ratio, and reduces time spent illuminating sites of no interest. However, random-access AO scanning has not yet been combined with multi-photon microscopy, primarily because the femtosecond laser pulses employed are subject to significant amounts of both spatial and temporal dispersion upon propagation through common AO materials. Left uncompensated, spatial dispersion reduces the microscope"s spatial resolution while temporal dispersion reduces the multi-photon excitation efficacy. In previous work, we have demonstrated, 1) the efficacy of a single diffraction grating scheme which reduces the spatial dispersion at least 3-fold throughout the field-of-view, and 2) the use of a novel stacked-prism pre-chirper for compensating the temporal dispersion of a pair of AODs using a shorter mechanical path length (2-4X) than standard prism-pair arrangements. In this work, we demonstrate for the first time the use of these compensation approaches with a custom-made large-area slow-shear TeO2 AOD specifically suited for the development of a high-resolution 2-D random-access AO scanning multi-photon laser-scanning microscope (AO-MPLSM).

Appraisal of lupus nephritis by renal imaging with gallium-67

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

Bakir, A.A.; Lopez-Majano, V.; Hryhorczuk, D.O.

1985-08-01

To assess the activity of lupus nephritis, 43 patients with systemic lupus erythematosus (SLE) were studied by gallium imaging. Delayed renal visualization 48 hours after the gallium injection, a positive result, was noted in 25 of 48 scans. Active renal disease was defined by the presence of hematuria, pyuria (10 or more red blood cells or white blood cells per high-power field), proteinuria (1 g or more per 24 hours), a rising serum creatinine level, or a recent biopsy specimen showing proliferative and/or necrotizing lesions involving more than 20 percent of glomeruli. Renal disease was active in 18 instances, inactivemore » in 23, and undetermined in seven (a total of 48 scans). Sixteen of the 18 scans (89 percent) in patients with active renal disease showed positive findings, as compared with only four of 23 scans (17 percent) in patients with inactive renal disease (p less than 0.001). Patients with positive scanning results had a higher rate of hypertension (p = 0.02), nephrotic proteinuria (p = 0.01), and progressive renal failure (p = 0.02). Mild mesangial nephritis (World Health Organization classes I and II) was noted only in the patients with negative scanning results (p = 0.02) who, however, showed a higher incidence of severe extrarenal SLE (p = 0.04). It is concluded that gallium imaging is a useful tool in evaluating the activity of lupus nephritis.« less

Scan-o-matic: High-Resolution Microbial Phenomics at a Massive Scale

PubMed Central

Zackrisson, Martin; Hallin, Johan; Ottosson, Lars-Göran; Dahl, Peter; Fernandez-Parada, Esteban; Ländström, Erik; Fernandez-Ricaud, Luciano; Kaferle, Petra; Skyman, Andreas; Stenberg, Simon; Omholt, Stig; Petrovič, Uroš; Warringer, Jonas; Blomberg, Anders

2016-01-01

The capacity to map traits over large cohorts of individuals—phenomics—lags far behind the explosive development in genomics. For microbes, the estimation of growth is the key phenotype because of its link to fitness. We introduce an automated microbial phenomics framework that delivers accurate, precise, and highly resolved growth phenotypes at an unprecedented scale. Advancements were achieved through the introduction of transmissive scanning hardware and software technology, frequent acquisition of exact colony population size measurements, extraction of population growth rates from growth curves, and removal of spatial bias by reference-surface normalization. Our prototype arrangement automatically records and analyzes close to 100,000 growth curves in parallel. We demonstrate the power of the approach by extending and nuancing the known salt-defense biology in baker’s yeast. The introduced framework represents a major advance in microbial phenomics by providing high-quality data for extensive cohorts of individuals and generating well-populated and standardized phenomics databases PMID:27371952

Accurate 3D reconstruction by a new PDS-OSEM algorithm for HRRT

NASA Astrophysics Data System (ADS)

Chen, Tai-Been; Horng-Shing Lu, Henry; Kim, Hang-Keun; Son, Young-Don; Cho, Zang-Hee

2014-03-01

State-of-the-art high resolution research tomography (HRRT) provides high resolution PET images with full 3D human brain scanning. But, a short time frame in dynamic study causes many problems related to the low counts in the acquired data. The PDS-OSEM algorithm was proposed to reconstruct the HRRT image with a high signal-to-noise ratio that provides accurate information for dynamic data. The new algorithm was evaluated by simulated image, empirical phantoms, and real human brain data. Meanwhile, the time activity curve was adopted to validate a reconstructed performance of dynamic data between PDS-OSEM and OP-OSEM algorithms. According to simulated and empirical studies, the PDS-OSEM algorithm reconstructs images with higher quality, higher accuracy, less noise, and less average sum of square error than those of OP-OSEM. The presented algorithm is useful to provide quality images under the condition of low count rates in dynamic studies with a short scan time.

Radiation safety audit of a high volume Nuclear Medicine Department.

PubMed

Jha, Ashish Kumar; Singh, Abhijith Mohan; Shetye, Bhakti; Shah, Sneha; Agrawal, Archi; Purandare, Nilendu Chandrakant; Monteiro, Priya; Rangarajan, Venkatesh

2014-10-01

Professional radiation exposure cannot be avoided in nuclear medicine practices. It can only be minimized up to some extent by implementing good work practices. The aim of our study was to audit the professional radiation exposure and exposure rate of radiation worker working in and around Department of nuclear medicine and molecular imaging, Tata Memorial Hospital. We calculated the total number of nuclear medicine and positron emission tomography/computed tomography (PET/CT) procedures performed in our department and the radiation exposure to the radiation professionals from year 2009 to 2012. We performed an average of 6478 PET/CT scans and 3856 nuclear medicine scans/year from January 2009 to December 2012. The average annual whole body radiation exposure to nuclear medicine physician, technologist and nursing staff are 1.74 mSv, 2.93 mSv and 4.03 mSv respectively. Efficient management and deployment of personnel is of utmost importance to optimize radiation exposure in a high volume nuclear medicine setup in order to work without anxiety of high radiation exposure.

Two-dimensional scanning high-energy particle diagnostic system in Large Helical Device

NASA Astrophysics Data System (ADS)

Ozaki, T.; Goncharov, P.; Sudo, S.; Shoji, M.; Kawahata, K.; Kaneko, O.; Murakami, S.

2004-10-01

A high-energy neutral particle measurement is one of the important diagnostics for ion temperature and high-energy particle confinement analysis. The neutral particle analyzer in the large helical device is capable of wide range scanning as a feature. We have obtained various data using the horizontal scan of the analyzer. Recently, in addition to the horizontal scan, a high-speed perpendicular scan became possible which enables acquisition of new information in the poloidal direction. Two stainless blocks are set on the opposite sides of the chain in order to balance the weight (700 kg) of the analyzer and reduce the load for the motor. Therefore a very high scan speed of 1°/s can be obtained. The scanning speed is 1°/s. By adding the vertical scan, the ion temperature profile and the radial variation of the signal loss associated with the resonant loss was obtained in preliminary experimental results.

Randomized, single-blind, factorial design study of the interaction of food and time on intestinal activity in 99mTc-tetrofosmin stress myocardial perfusion scintigraphy.

PubMed

Lyngholm, Ann Marie; Pedersen, Begitte H; Petersen, Lars J

2008-09-01

Intestinal activity at the inferior myocardial wall represents an issue for assessment of myocardial perfusion imaging (MPI) with 99mTc-labelled tracers. The aim of this study was to investigate the effect of time and food on upper abdominal activity in 99mTc-tetrofosmin MPI. The study population consisted of 152 consecutive patients referred for routine MPI. All patients underwent 2-day stress-rest 99mTc-tetrofosmin single-photon emission computed tomography MPI. Before stress testing, patients were randomized in a factorial design to four different regimens. Group A: early scan (image acquisition initiated within 15 min after injection of the tracer) and no food; group B: early scan and food (two pieces of white bread with butter and a minimum of 450 ml of water); group C: late scan (image acquisition 30-60 min after injection of the tracer) and no food; and group D: late and scan with food. Patients underwent standard bicycle exercise or pharmacological stress test. The degree of upper abdominal activity was evaluated by trained observers blinded to the randomization code. The primary endpoint was the proportion of accepted scans in the intention-to-treat population in stress MPI. The results showed statistical significant impact on both time and food on upper abdominal activity. The primary endpoint showed that the acceptance rate improved from 55% in group A to 100% success rate in group D. An early scan reduced the acceptance rate by 30% versus a late scan [hazard ratio 0.70, 95% confidence interval 0.58-0.84; P<0.0001], whereas the addition of food improved the success rate versus no food by 27% (hazard ratio 1.27, 95% confidence interval 1.07-1.51; P=0.006). No significant interaction between food and time was observed. An analysis of accepted scans according to the actual scan time and food consumption confirmed the findings of the intention-to-treat analysis. In addition, similar findings were seen in 116 of 152 patients with a rest MPI (success rate of 53% in group A vs. 96% in group D). A combination of solid food and water administered after injection of the tracer and delayed image acquisition led to significant and clinically relevant decrease of interfering upper abdominal activity in 99mTc-tetrofosmin MPI.

Transforming Pristine Carbon Fiber Tows into High Performance Solid-State Fiber Supercapacitors.

PubMed

Yu, Dingshan; Zhai, Shengli; Jiang, Wenchao; Goh, Kunli; Wei, Li; Chen, Xudong; Jiang, Rongrong; Chen, Yuan

2015-09-02

A facile activation strategy can transform pristine carbon fiber tows into high-performance fiber electrodes with a specific capacitance of 14.2 F cm(-3) . The knottable fiber supercapacitor shows an energy density of 0.35 mW h cm(-3) , an ultrahigh power density of 3000 mW cm(-3) , and a remarkable capacitance retention of 68%, when the scan rate increases from 10 to 1000 mV s(-1) . © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Fast Confocal Raman Imaging Using a 2-D Multifocal Array for Parallel Hyperspectral Detection.

PubMed

Kong, Lingbo; Navas-Moreno, Maria; Chan, James W

2016-01-19

We present the development of a novel confocal hyperspectral Raman microscope capable of imaging at speeds up to 100 times faster than conventional point-scan Raman microscopy under high noise conditions. The microscope utilizes scanning galvomirrors to generate a two-dimensional (2-D) multifocal array at the sample plane, generating Raman signals simultaneously at each focus of the array pattern. The signals are combined into a single beam and delivered through a confocal pinhole before being focused through the slit of a spectrometer. To separate the signals from each row of the array, a synchronized scan mirror placed in front of the spectrometer slit positions the Raman signals onto different pixel rows of the detector. We devised an approach to deconvolve the superimposed signals and retrieve the individual spectra at each focal position within a given row. The galvomirrors were programmed to scan different focal arrays following Hadamard encoding patterns. A key feature of the Hadamard detection is the reconstruction of individual spectra with improved signal-to-noise ratio. Using polystyrene beads as test samples, we demonstrated not only that our system images faster than a conventional point-scan method but that it is especially advantageous under noisy conditions, such as when the CCD detector operates at fast read-out rates and high temperatures. This is the first demonstration of multifocal confocal Raman imaging in which parallel spectral detection is implemented along both axes of the CCD detector chip. We envision this novel 2-D multifocal spectral detection technique can be used to develop faster imaging spontaneous Raman microscopes with lower cost detectors.

Multi-residue determination of seventeen sulfonamides and five tetracyclines in fish tissue using a multi-stage LC-ESI-MS/MS approach based on advanced mass spectrometric techniques.

PubMed

Dasenaki, Marilena E; Thomaidis, Nikolaos S

2010-07-05

A strategy was newly developed to rapidly screen seventeen sulfonamides and five tetracyclines in a single run from fish tissues using ultra-high performance liquid chromatography (UHPLC) coupled with comprehensive mass spectrometric approaches, including precursor-ion scan and data dependent scan. The product ions for precursor-ion scanning were selected by studying the MS/MS fragmentation of the analytes. All sulfonamides share the same diagnostic product ion at m/z 156 in positive MS/MS scan, while for tetracycline antibiotics the diagnostic product ion was proved to be at m/z 153.8. Further characterization of each compound was performed using a data dependent scan. Separation was performed on a Zorbax Eclipse Plus C18 column with a gradient elution using acetonitrile - 0.1% formic acid mobile phase at a flow rate of 0.1 mL min(-1). This approach has proven to be a powerful, highly selective, and sensitive tool for rapid screening and detection of non-targeted components in fish tissue and requires a minimum sample preparation such as one generic extraction step with MeOH:ACN 50:50 (v/v) acidified with 0.05% formic acid. The method has also been applied successfully to porcine and poultry meat. The validation of such a screening method was performed for the first time according to Commission Decision 2002/657/EC and satisfactory method performance characteristics were achieved. Copyright 2010 Elsevier B.V. All rights reserved.

Synchrotron studies of top-down grown silicon nanowires

NASA Astrophysics Data System (ADS)

Turishchev, S. Yu.; Parinova, E. V.; Nesterov, D. N.; Koyuda, D. A.; Sivakov, V.; Schleusener, A.; Terekhov, V. A.

2018-06-01

Morphology of the top-down grown silicon nanowires obtained by metal-assisted wet-chemical approach on silicon substrates with different resistance were studied by scanning electron microscopy. Obtained arrays of compact grown Si nanowires were a subject for the high resolution electronic structures studies by X-ray absorption near edge structure technique performed with the usage of high intensity synchrotron radiation of the SRC storage ring of the University of Wisconsin-Madison. The different oxidation rates were found by investigation of silicon atoms local surrounding specificity of the highly developed surface and near surface layer that is not exceeded 70 nm. Flexibility of the wires arrays surface morphology and its composition is demonstrated allowing smoothly form necessary surface oxidation rate and using Si nanowires as a useful matrixes for a wide range of further functionalization.

Multiphoton imaging with high peak power VECSELs

NASA Astrophysics Data System (ADS)

Mirkhanov, Shamil; Quarterman, Adrian H.; Swift, Samuel; Praveen, Bavishna B.; Smyth, Conor J. C.; Wilcox, Keith G.

2016-03-01

Multiphoton imaging (MMPI) has become one of thee key non-invasive light microscopy techniques. This technique allows deep tissue imaging with high resolution and less photo-damage than conventional confocal microscopy. MPI is type of laser-scanning microscopy that employs localized nonlinear excitation, so that fluorescence is excited only with is scanned focal volume. For many years, Ti: sapphire femtosecond lasers have been the leading light sources for MPI applications. However, recent developments in laser sources and new types of fluorophores indicate that longer wavelength excitation could be a good alternative for these applications. Mode-locked VECSEELs have the potential to be low cost, compact light sources for MPI systems, with the additional advantage of broad wavelength coverage through use of different semiconductor material systems. Here, we use a femtosecond fibber laser to investigate the effect average power and repetition rate has on MPI image quality, to allow us to optimize our mode-locked VVECSELs for MPI.

A compact acousto-optic lens for 2D and 3D femtosecond based 2-photon microscopy

PubMed Central

Kirkby, Paul A.; Naga Srinivas, N.K.M.; Silver, R. Angus

2010-01-01

We describe a high speed 3D Acousto-Optic Lens Microscope (AOLM) for femtosecond 2-photon imaging. By optimizing the design of the 4 AO Deflectors (AODs) and by deriving new control algorithms, we have developed a compact spherical AOL with a low temporal dispersion that enables 2-photon imaging at 10-fold lower power than previously reported. We show that the AOLM can perform high speed 2D raster-scan imaging (>150 Hz) without scan rate dependent astigmatism. It can deflect and focus a laser beam in a 3D random access sequence at 30 kHz and has an extended focusing range (>137 μm; 40X 0.8NA objective). These features are likely to make the AOLM a useful tool for studying fast physiological processes distributed in 3D space PMID:20588506

Milligram-per-second femtosecond laser production of Se nanoparticle inks and ink-jet printing of nanophotonic 2D-patterns

NASA Astrophysics Data System (ADS)

Ionin, Andrey; Ivanova, Anastasia; Khmel'nitskii, Roman; Klevkov, Yury; Kudryashov, Sergey; Mel'nik, Nikolay; Nastulyavichus, Alena; Rudenko, Andrey; Saraeva, Irina; Smirnov, Nikita; Zayarny, Dmitry; Baranov, Anatoly; Kirilenko, Demid; Brunkov, Pavel; Shakhmin, Alexander

2018-04-01

Milligram-per-second production of selenium nanoparticles in water sols was realized through 7-W, 2 MHz-rate femtosecond laser ablation of a crystalline trigonal selenium pellet. High-yield particle formation mechanism and ultimate mass-removal yield were elucidated by optical profilometry and scanning electron microscopy characterization of the corresponding crater depths and topographies. Deposited selenium particles were inspected by scanning and transmission electron microscopy, while their hydrosols (nanoinks) were characterized by optical transmission, Raman and dynamic light scattering spectroscopy. 2D patterns and coatings were ink-jet printed on thin supported silver films and their bare silica glass substrates, as well as on IR-transparent CaF2 substrates, and characterized by electron microscopy, energy-dispersive x-ray spectroscopy, and broadband (vis-mid IR) transmission spectroscopy, exhibiting crystalline selenium nanoparticles with high refractive index as promising all-dielectric sensing building nanoblocks in nanophotonics.

Defect Inspection of Flip Chip Solder Bumps Using an Ultrasonic Transducer

PubMed Central

Su, Lei; Shi, Tielin; Xu, Zhensong; Lu, Xiangning; Liao, Guanglan

2013-01-01

Surface mount technology has spurred a rapid decrease in the size of electronic packages, where solder bump inspection of surface mount packages is crucial in the electronics manufacturing industry. In this study we demonstrate the feasibility of using a 230 MHz ultrasonic transducer for nondestructive flip chip testing. The reflected time domain signal was captured when the transducer scanning the flip chip, and the image of the flip chip was generated by scanning acoustic microscopy. Normalized cross-correlation was used to locate the center of solder bumps for segmenting the flip chip image. Then five features were extracted from the signals and images. The support vector machine was adopted to process the five features for classification and recognition. The results show the feasibility of this approach with high recognition rate, proving that defect inspection of flip chip solder bumps using the ultrasonic transducer has high potential in microelectronics packaging.

Vertebral osteomyelitis caused by Prevotella (Bacteroides) melaninogenicus.

PubMed

Mukhopadhyay, Surabhi; Rose, Fredrick; Frechette, Vincent

2005-02-01

A 35-year-old, previously healthy female presented with severe low back pain, fever, and a high erythrocyte sedimentation rate 1 week after a routine dental cleaning. Technetium-labeled leukocyte scanning and magnetic resonance imaging scan of the spine were negative for osteomyelitis. The patient underwent biopsy, cultures from which grew Prevotella (Bacteroides) melaninogenicus. Appropriate antibiotic therapy resulted in resolution of symptoms. P. melaninogenicus is a gram-negative anaerobic bacillus that is part of the indigenous oral flora. It may cause dental, sinus, skin, and soft tissue infections. Infection of bone is rare. Only three cases of vertebral osteomyelitis due to P. melaninogenicus have been reported in the literature. The early diagnosis of vertebral osteomyelitis requires a high index of clinical suspicion and cannot be excluded by negative imaging tests alone. The recovery of this unusual organism highlights the importance of requesting anaerobic cultures of biopsy specimens.

Trends and patterns in the use of computed tomography in children and young adults in Catalonia - results from the EPI-CT study.

PubMed

Bosch de Basea, Magda; Salotti, Jane A; Pearce, Mark S; Muchart, Jordi; Riera, Luis; Barber, Ignasi; Pedraza, Salvador; Pardina, Marina; Capdevila, Antoni; Espinosa, Ana; Cardis, Elisabeth

2016-01-01

Although there are undeniable diagnostic benefits of CT scanning, its increasing use in paediatric radiology has become a topic of concern regarding patient radioprotection. To assess the rate of CT scanning in Catalonia, Spain, among patients younger than 21 years old at the scan time. This is a sub-study of a larger international cohort study (EPI-CT, the International pediatric CT scan study). Data were retrieved from the radiological information systems (RIS) of eight hospitals in Catalonia since the implementation of digital registration (between 1991 and 2010) until 2013. The absolute number of CT scans annually increased 4.5% between 1991 and 2013, which was less accentuated when RIS was implemented in most hospitals. Because the population attending the hospitals also increased, however, the rate of scanned patients changed little (8.3 to 9.4 per 1,000 population). The proportions of patients with more than one CT and more than three CTs showed a 1.51- and 2.7-fold increase, respectively, over the 23 years. Gradual increases in numbers of examinations and scanned patients were observed in Catalonia, potentially explained by new CT scanning indications and increases in the availability of scanners, the number of scans per patient and the size of the attended population.

Corrosion of Nickel-Based Alloys in Ultra-High Temperature Heat Transfer Fluid

NASA Astrophysics Data System (ADS)

Wang, Tao; Reddy, Ramana G.

2017-03-01

MgCl2-KCl binary system has been proposed to be used as high temperature reactor coolant. Due to its relatively low melting point, good heat capacity and excellent thermal stability, this system can also be used in high operation temperature concentrating solar power generation system as heat transfer fluid (HTF). The corrosion behaviors of nickel based alloys in MgCl2-KCl molten salt system at 1,000 °C were determined based on long-term isothermal dipping test. After 500 h exposure tests under strictly maintained high purity argon gas atmosphere, the weight loss and corrosion rate analysis were conducted. Among all the tested samples, Ni-201 demonstrated the lowest corrosion rate due to the excellent resistance of Ni to high temperature element dissolution. Detailed surface topography and corrosion mechanisms were also determined by using scanning electron microscopy (SEM) equipped with energy dispersive spectrometer (EDS).

Fine-tuned Remote Laser Welding of Aluminum to Copper with Local Beam Oscillation

NASA Astrophysics Data System (ADS)

Fetzer, Florian; Jarwitz, Michael; Stritt, Peter; Weber, Rudolf; Graf, Thomas

Local beam oscillation in remote laser welding of aluminum to copper was investigated. Sheets of 1 mm thickness were welded in overlap configuration with aluminum as top material. The laser beam was scanned in a sinusoidal mode perpendicular to the direction of feed and the influence of the oscillation parameters frequency and amplitude on the weld geometry was investigated. Scanning frequencies up to 1 kHz and oscillation amplitudes in the range from 0.25 mm to 1 mm were examined. Throughout the experiments the laser power and the feed rate were kept constant. A decrease of welding depth with amplitude and frequency is found. The scanning amplitude had a strong influence and allowed coarse setting of the welding depth into the lower material, while the frequency allowed fine tuning in the order of 10% of the obtained depth. The oscillation parameters were found to act differently on the aluminum sheet compared to copper sheet regarding the amount of fused material. It is possible to influence the geometry of the fused zones separately for both sheets. Therefore the average composition in the weld can be set with high precision via the oscillation parameters. A setting of the generated intermetallics in the weld zone is possible without adjustment of laser power and feed rate.

Assessing the kidney function parameters glomerular filtration rate and effective renal plasma flow with dynamic FDG-PET/MRI in healthy subjects.

PubMed

Geist, Barbara K; Baltzer, Pascal; Fueger, Barbara; Hamboeck, Martina; Nakuz, Thomas; Papp, Laszlo; Rasul, Sazan; Sundar, Lalith Kumar Shiyam; Hacker, Marcus; Staudenherz, Anton

2018-05-09

A method was developed to assess the kidney parameters glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) from 2-deoxy-2-[ 18 F]fluoro-D-glucose (FDG) concentration behavior in kidneys, measured with positron emission tomography (PET) scans. Twenty-four healthy adult subjects prospectively underwent dynamic simultaneous PET/magnetic resonance imaging (MRI) examination. Time activity curves (TACs) were obtained from the dynamic PET series, with the guidance of MR information. Patlak analysis was performed to determine the GFR, and based on integrals, ERPF was calculated. Results were compared to intra-individually obtained reference values determined from venous blood samples. Total kidney GFR and ERPF as estimated by dynamic PET/MRI were highly correlated to their reference values (r = 0.88/p < 0.0001 and r = 0.82/p < 0.0001, respectively) with no significant difference between their means. The study is a proof of concept that GFR and ERPF can be assessed with dynamic FDG PET/MRI scans in healthy kidneys. This has advantages for patients getting a routine scan, where additional examinations for kidney function estimation could be avoided. Further studies are required for transferring this PET/MRI method to PET/CT applications.

Swept source optical coherence microscopy using a 1310 nm VCSEL light source

PubMed Central

Ahsen, Osman O.; Tao, Yuankai K.; Potsaid, Benjamin M.; Sheikine, Yuri; Jiang, James; Grulkowski, Ireneusz; Tsai, Tsung-Han; Jayaraman, Vijaysekhar; Kraus, Martin F.; Connolly, James L.; Hornegger, Joachim; Cable, Alex; Fujimoto, James G.

2013-01-01

We demonstrate high speed, swept source optical coherence microscopy (OCM) using a MEMS tunable vertical cavity surface-emitting laser (VCSEL) light source. The light source had a sweep rate of 280 kHz, providing a bidirectional axial scan rate of 560 kHz. The sweep bandwidth was 117 nm centered at 1310 nm, corresponding to an axial resolution of 13.1 µm in air, corresponding to 8.1 µm (9.6 µm spectrally shaped) in tissue. Dispersion mismatch from different objectives was compensated numerically, enabling magnification and field of view to be easily changed. OCM images were acquired with transverse resolutions between 0.86 µm - 3.42 µm using interchangeable 40X, 20X and 10X objectives with ~600 µm x 600 µm, ~1 mm x 1 mm and ~2 mm x 2 mm field-of-view (FOV), respectively. Parasitic variations in path length with beam scanning were corrected numerically. These features enable swept source OCM to be integrated with a wide range of existing scanning microscopes. Large FOV mosaics were generated by serially acquiring adjacent overlapping microscopic fields and combining them in post-processing. Fresh human colon, thyroid and kidney specimens were imaged ex vivo and compared to matching histology sections, demonstrating the ability of OCM to image tissue specimens. PMID:23938673

Hydrogenated TiO2 nanotube arrays for supercapacitors.

PubMed

Lu, Xihong; Wang, Gongming; Zhai, Teng; Yu, Minghao; Gan, Jiayong; Tong, Yexiang; Li, Yat

2012-03-14

We report a new and general strategy for improving the capacitive properties of TiO(2) materials for supercapacitors, involving the synthesis of hydrogenated TiO(2) nanotube arrays (NTAs). The hydrogenated TiO(2) (denoted as H-TiO(2)) were obtained by calcination of anodized TiO(2) NTAs in hydrogen atmosphere in a range of temperatures between 300 to 600 °C. The H-TiO(2) NTAs prepared at 400 °C yields the largest specific capacitance of 3.24 mF cm(-2) at a scan rate of 100 mV s(-1), which is 40 times higher than the capacitance obtained from air-annealed TiO(2) NTAs at the same conditions. Importantly, H-TiO(2) NTAs also show remarkable rate capability with 68% areal capacitance retained when the scan rate increase from 10 to 1000 mV s(-1), as well as outstanding long-term cycling stability with only 3.1% reduction of initial specific capacitance after 10,000 cycles. The prominent electrochemical capacitive properties of H-TiO(2) are attributed to the enhanced carrier density and increased density of hydroxyl group on TiO(2) surface, as a result of hydrogenation. Furthermore, we demonstrate that H-TiO(2) NTAs is a good scaffold to support MnO(2) nanoparticles. The capacitor electrodes made by electrochemical deposition of MnO(2) nanoparticles on H-TiO(2) NTAs achieve a remarkable specific capacitance of 912 F g(-1) at a scan rate of 10 mV s(-1) (based on the mass of MnO(2)). The ability to improve the capacitive properties of TiO(2) electrode materials should open up new opportunities for high-performance supercapacitors. © 2012 American Chemical Society

A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans.

PubMed

Chen, Xu; Guo, Tengfei; Hou, Yubin; Zhang, Jing; Meng, Wenjie; Lu, Qingyou

2017-01-01

A new scan-head structure for the scanning tunneling microscope (STM) is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans) coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan). They are fixed at one end (called common end). A hollow tantalum shaft is coaxially housed in the XY -scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

Pancreatic Cancer Tumor Size on CT Scan Versus Pathologic Specimen: Implications for Radiation Treatment Planning

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

Arvold, Nils D.; Niemierko, Andrzej; Mamon, Harvey J.

2011-08-01

Purpose: Pancreatic cancer primary tumor size measurements are often discordant between computed tomography (CT) and pathologic specimen after resection. Dimensions of the primary tumor are increasingly relevant in an era of highly conformal radiotherapy. Methods and Materials: We retrospectively evaluated 97 consecutive patients with resected pancreatic cancer at two Boston hospitals. All patients had CT scans before surgical resection. Primary endpoints were maximum dimension (in millimeters) of the primary tumor in any direction as reported by the radiologist on CT and by the pathologist for the resected gross fresh specimen. Endoscopic ultrasound (EUS) findings were analyzed if available. Results: Ofmore » the patients, 87 (90%) had preoperative CT scans available for review and 46 (47%) had EUS. Among proximal tumors (n = 69), 40 (58%) had pathologic duodenal invasion, which was seen on CT in only 3 cases. The pathologic tumor size was a median of 7 mm larger compared with CT size for the same patient (range, -15 to 43 mm; p < 0.0001), with 73 patients (84%) having a primary tumor larger on pathology than CT. Endoscopic ultrasound was somewhat more accurate, with pathologic tumor size being a median of only 5 mm larger compared with EUS size (range, -15 to 35 mm; p = 0.0003). Conclusions: Computed tomography scans significantly under-represent pancreatic cancer tumor size compared with pathologic specimens in resectable cases. We propose a clinical target volume expansion formula for the primary tumor based on our data. The high rate of pathologic duodenal invasion suggests a risk of duodenal undercoverage with highly conformal radiotherapy.« less

Are clinical, laboratory, and imaging markers suitable predictors of vesicoureteral reflux in children with their first febrile urinary tract infection?

PubMed

Mahyar, Abolfazl; Ayazi, Parviz; Mavadati, Shiva; Oveisi, Sonia; Habibi, Morteza; Esmaeily, Shiva

2014-08-01

This study was conducted to determine the predictive value of clinical, laboratory, and imaging variables for the diagnosis of vesicoureteral reflux in children with their first febrile urinary tract infection. One hundred fifty-three children with their first febrile urinary tract infection were divided into two groups according to the results of voiding cystourethrography: 60 children with vesicoureteral reflux and 93 children without. The sensitivity, specificity, positive and negative predictive value, likelihood ratio (positive and negative), and accuracy of the clinical, laboratory, and imaging variables for the diagnosis of vesicoureteral reflux were determined. Of the 153 children with febrile urinary tract infection, 60 patients (39.2%) had vesicoureteral reflux. There were significant differences between the two groups regarding fever>38℃, suprapubic pain, C-reactive protein quantitative level, number of red blood cells in the urine, and results of renal ultrasound and dimercaptosuccinic acid renal scanning (p<0.05). There were significant positive correlations between fever>38.2℃ and dimercaptosuccinic acid renal scanning and vesicoureteral reflux. Also, there were significant positive correlations between the erythrocyte sedimentation rate, positive urinary nitrite test, hyaline cast, and renal ultrasound and high-grade vesicoureteral reflux. This study revealed fever>38.2℃ and dimercaptosuccinic acid renal scanning as the best predictive markers for vesicoureteral reflux in children with their first febrile urinary tract infection. In addition, erythrocyte sedimentation rate, positive urinary nitrite test, hyaline cast, and renal ultrasound are the best predictive markers for high-grade vesicoureteral reflux.

Are Clinical, Laboratory, and Imaging Markers Suitable Predictors of Vesicoureteral Reflux in Children With Their First Febrile Urinary Tract Infection?

PubMed Central

Ayazi, Parviz; Mavadati, Shiva; Oveisi, Sonia; Habibi, Morteza; Esmaeily, Shiva

2014-01-01

Purpose This study was conducted to determine the predictive value of clinical, laboratory, and imaging variables for the diagnosis of vesicoureteral reflux in children with their first febrile urinary tract infection. Materials and Methods One hundred fifty-three children with their first febrile urinary tract infection were divided into two groups according to the results of voiding cystourethrography: 60 children with vesicoureteral reflux and 93 children without. The sensitivity, specificity, positive and negative predictive value, likelihood ratio (positive and negative), and accuracy of the clinical, laboratory, and imaging variables for the diagnosis of vesicoureteral reflux were determined. Results Of the 153 children with febrile urinary tract infection, 60 patients (39.2%) had vesicoureteral reflux. There were significant differences between the two groups regarding fever>38℃, suprapubic pain, C-reactive protein quantitative level, number of red blood cells in the urine, and results of renal ultrasound and dimercaptosuccinic acid renal scanning (p<0.05). There were significant positive correlations between fever>38.2℃ and dimercaptosuccinic acid renal scanning and vesicoureteral reflux. Also, there were significant positive correlations between the erythrocyte sedimentation rate, positive urinary nitrite test, hyaline cast, and renal ultrasound and high-grade vesicoureteral reflux. Conclusions This study revealed fever>38.2℃ and dimercaptosuccinic acid renal scanning as the best predictive markers for vesicoureteral reflux in children with their first febrile urinary tract infection. In addition, erythrocyte sedimentation rate, positive urinary nitrite test, hyaline cast, and renal ultrasound are the best predictive markers for high-grade vesicoureteral reflux. PMID:25132949

Scanning Synchronization of Colliding Bunches for MEIC Project

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

Derbenev, Yaroslav S.; Popov, V. P.; Chernousov, Yu D.

2015-09-01

Synchronization of colliding beams is one of the major issues of an electron-ion collider (EIC) design because of sensitivity of ion revolution frequency to beam energy. A conventional solution for this trouble is insertion of bent chicanes in the arcs space. In our report we consider a method to provide space coincidence of encountering bunches in the crab-crossing orbits Interaction Region (IR) while repetition rates of two beams do not coincide. The method utilizes pair of fast kickers realizing a bypass for the electron bunches as the way to equalize positions of the colliding bunches at the Interaction Point (IP).more » A dipole-mode warm or SRF cavities fed by the magnetron transmitters are used as fast kickers, allowing a broad-band phase and amplitude control. The proposed scanning synchronization method implies stabilization of luminosity at a maximum via a feedback loop. This synchronization method is evaluated as perspective for the Medium Energy Electron-Ion collider (MEIC) project of JLab with its very high bunch repetition rate.« less

Sensitive power compensated scanning calorimeter for analysis of phase transformations in small samples

NASA Astrophysics Data System (ADS)

Lopeandía, A. F.; Cerdó, L. l.; Clavaguera-Mora, M. T.; Arana, Leonel R.; Jensen, K. F.; Muñoz, F. J.; Rodríguez-Viejo, J.

2005-06-01

We have designed and developed a sensitive scanning calorimeter for use with microgram or submicrogram, thin film, or powder samples. Semiconductor processing techniques are used to fabricate membrane based microreactors with a small heat capacity of the addenda, 120nJ/K at room temperature. At heating rates below 10K/s the heat released or absorbed by the sample during a given transformation is compensated through a resistive Pt heater by a digital controller so that the calorimeter works as a power compensated device. Its use and dynamic sensitivity is demonstrated by analyzing the melting behavior of thin films of indium and high density polyethylene. Melting enthalpies in the range of 40-250μJ for sample masses on the order of 1.5μg have been measured with accuracy better than 5% at heating rates ˜0.2K/s. The signal-to-noise ratio, limited by the electronic setup, is 200nW.

Multibeam Antenna Design and Development for NASA Advanced Communications Technology Satellite (ACTS)

NASA Technical Reports Server (NTRS)

Choung, Youn H.; Wong, William C.

1986-01-01

The design of the ACTS multibeam antenna is described, and its performance is evaluated. The multibeam antenna is designed to cover the continential U.S. and provides three fixed spot beams for high burst rate operations and two scanning beams for low burst rate operations. The antenna has one main reflector, a dual polarized subreflector, and two orthogonal feed assemblies. The feed system is to receive a linearly polarized communication signal from 28.9-30.0 GHz and to provide the elevation and azimuth error tracking signals at 29.975 GHz with a 0.01 deg tracking accuracy. The feed system uses a single multiflare conical horn and a multimode coupler to provide a symmetric primary pattern for the communication signal. The sidelobe characteristics of the reflector, and the relation between the sidelobe level and surface distortion are studied. It is noted that the performance measurements for the multibeam antenna correlate well with predictions for secondary patterns and scan characteristics.

Results From the Imaging and Radiation Oncology Core Houston's Anthropomorphic Phantoms Used for Proton Therapy Clinical Trial Credentialing

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

Taylor, Paige A., E-mail: pataylor@mdanderson.org; Kry, Stephen F.; Alvarez, Paola

Purpose: The purpose of this study was to summarize the findings of anthropomorphic proton phantom irradiations analyzed by the Imaging and Radiation Oncology Core Houston QA Center (IROC Houston). Methods and Materials: A total of 103 phantoms were irradiated by proton therapy centers participating in clinical trials. The anthropomorphic phantoms simulated heterogeneous anatomy of a head, liver, lung, prostate, and spine. Treatment plans included those for scattered, uniform scanning, and pencil beam scanning beam delivery modalities using 5 different treatment planning systems. For every phantom irradiation, point doses and planar doses were measured using thermoluminescent dosimeters (TLD) and film, respectively. Differencesmore » between measured and planned doses were studied as a function of phantom, beam delivery modality, motion, repeat attempt, treatment planning system, and date of irradiation. Results: The phantom pass rate (overall, 79%) was high for simple phantoms and lower for phantoms that introduced higher levels of difficulty, such as motion, multiple targets, or increased heterogeneity. All treatment planning systems overestimated dose to the target, compared to TLD measurements. Errors in range calculation resulted in several failed phantoms. There was no correlation between treatment planning system and pass rate. The pass rates for each individual phantom are not improving over time, but when individual institutions received feedback about failed phantom irradiations, pass rates did improve. Conclusions: The proton phantom pass rates are not as high as desired and emphasize potential deficiencies in proton therapy planning and/or delivery. There are many areas for improvement with the proton phantom irradiations, such as treatment planning system dose agreement, range calculations, accounting for motion, and irradiation of multiple targets.« less

Quantification of rapid environmental redox processes with quick-scanning x-ray absorption spectroscopy (Q-XAS)

PubMed Central

Ginder-Vogel, Matthew; Landrot, Gautier; Fischel, Jason S.; Sparks, Donald L.

2009-01-01

Quantification of the initial rates of environmental reactions at the mineral/water interface is a fundamental prerequisite to determining reaction mechanisms and contaminant transport modeling and predicting environmental risk. Until recently, experimental techniques with adequate time resolution and elemental sensitivity to measure initial rates of the wide variety of environmental reactions were quite limited. Techniques such as electron paramagnetic resonance and Fourier transform infrared spectroscopies suffer from limited elemental specificity and poor sensitivity to inorganic elements, respectively. Ex situ analysis of batch and stirred-flow systems provides high elemental sensitivity; however, their time resolution is inadequate to characterize rapid environmental reactions. Here we apply quick-scanning x-ray absorption spectroscopy (Q-XAS), at sub-second time-scales, to measure the initial oxidation rate of As(III) to As(V) by hydrous manganese(IV) oxide. Using Q-XAS, As(III) and As(V) concentrations were determined every 0.98 s in batch reactions. The initial apparent As(III) depletion rate constants (t < 30 s) measured with Q-XAS are nearly twice as large as rate constants measured with traditional analytical techniques. Our results demonstrate the importance of developing analytical techniques capable of analyzing environmental reactions on the same time scale as they occur. Given the high sensitivity, elemental specificity, and time resolution of Q-XAS, it has many potential applications. They could include measuring not only redox reactions but also dissolution/precipitation reactions, such as the formation and/or reductive dissolution of Fe(III) (hydr)oxides, solid-phase transformations (i.e., formation of layered-double hydroxide minerals), or almost any other reaction occurring in aqueous media that can be measured using x-ray absorption spectroscopy. PMID:19805269

High quality optical microangiography of ocular microcirculation and measurement of total retinal blood flow in mouse eye

NASA Astrophysics Data System (ADS)

Zhi, Zhongwei; Yin, Xin; Dziennis, Suzan; Alpers, Charles E.; Wang, Ruikang K.

2013-03-01

Visualization and measurement of retinal blood flow (RBF) is important to the diagnosis and management of different eye diseases, including diabetic retinopathy. Optical microangiography (OMAG) is developed for generating 3D dynamic microcirculation image and later refined into ultra-high sensitive OMAG (UHS-OMAG) for true capillary vessels imaging. Here, we present the application of OMAG imaging technique for visualization of depth-resolved vascular network within retina and choroid as well as measurement of total retinal blood flow in mice. A fast speed spectral domain OCT imaging system at 820nm with a line scan rate of 140 kHz was developed to image mouse posterior eye. By applying UHS-OMAG scanning protocol and processing algorithm, we achieved true capillary level imaging of retina and choroid vasculature in mouse eye. The vascular pattern within different retinal layers and choroid was presented. An en face Doppler OCT approach [1] without knowing Doppler angle was adopted for the measurement of total retinal blood flow. The axial blood flow velocity is measured in an en face plane by raster scanning and the flow is calculated by integrating over the vessel area of the central retinal artery.

Enhanced optical absorbance and fabrication of periodic arrays on nickel surface using nanosecond laser

NASA Astrophysics Data System (ADS)

Fu, Jinxiang; Liang, Hao; Zhang, Jingyuan; Wang, Yibo; Liu, Yannan; Zhang, Zhiyan; Lin, Xuechun

2017-04-01

A hundred-nanosecond pulsed laser was employed to structure the nickel surface. The effects of laser spatial filling interval and laser scanning speed on the optical absorbance capacity and morphologies on the nickel surface were experimentally investigated. The black nickel surface covered with dense micro/nanostructured broccoli-like clusters with strong light trapping capacity ranging from the UV to the near IR was produced at a high laser scanning speed up to v=100 mm/s. The absorbance of the black nickel is as high as 98% in the UV range of 200-400 nm, more than 97% in the visible spectrum, ranging from 400 to 800 nm, and over 90% in the IR between 800 and 2000 nm. In addition, when the nickel surface was irradiated in two-dimensional crossing scans by laser with different processing parameters, self-organized and shape-controllable structures of three-dimensional (3D) periodic arrays can be fabricated. Compared with ultrafast laser systems previously used for such processing, the nanosecond fiber laser used in this work is more cost-effective, compact and allows higher processing rates. This nickel surface structured technique may be applicable in optoelectronics, batteries industry, solar/wave absorbers, and wettability materials.

Digitally controlled analog proportional-integral-derivative (PID) controller for high-speed scanning probe microscopy

NASA Astrophysics Data System (ADS)

Dukic, Maja; Todorov, Vencislav; Andany, Santiago; Nievergelt, Adrian P.; Yang, Chen; Hosseini, Nahid; Fantner, Georg E.

2017-12-01

Nearly all scanning probe microscopes (SPMs) contain a feedback controller, which is used to move the scanner in the direction of the z-axis in order to maintain a constant setpoint based on the tip-sample interaction. The most frequently used feedback controller in SPMs is the proportional-integral (PI) controller. The bandwidth of the PI controller presents one of the speed limiting factors in high-speed SPMs, where higher bandwidths enable faster scanning speeds and higher imaging resolution. Most SPM systems use digital signal processor-based PI feedback controllers, which require analog-to-digital and digital-to-analog converters. These converters introduce additional feedback delays which limit the achievable imaging speed and resolution. In this paper, we present a digitally controlled analog proportional-integral-derivative (PID) controller. The controller implementation allows tunability of the PID gains over a large amplification and frequency range, while also providing precise control of the system and reproducibility of the gain parameters. By using the analog PID controller, we were able to perform successful atomic force microscopy imaging of a standard silicon calibration grating at line rates up to several kHz.

Digitally controlled analog proportional-integral-derivative (PID) controller for high-speed scanning probe microscopy.

PubMed

Dukic, Maja; Todorov, Vencislav; Andany, Santiago; Nievergelt, Adrian P; Yang, Chen; Hosseini, Nahid; Fantner, Georg E

2017-12-01

Nearly all scanning probe microscopes (SPMs) contain a feedback controller, which is used to move the scanner in the direction of the z-axis in order to maintain a constant setpoint based on the tip-sample interaction. The most frequently used feedback controller in SPMs is the proportional-integral (PI) controller. The bandwidth of the PI controller presents one of the speed limiting factors in high-speed SPMs, where higher bandwidths enable faster scanning speeds and higher imaging resolution. Most SPM systems use digital signal processor-based PI feedback controllers, which require analog-to-digital and digital-to-analog converters. These converters introduce additional feedback delays which limit the achievable imaging speed and resolution. In this paper, we present a digitally controlled analog proportional-integral-derivative (PID) controller. The controller implementation allows tunability of the PID gains over a large amplification and frequency range, while also providing precise control of the system and reproducibility of the gain parameters. By using the analog PID controller, we were able to perform successful atomic force microscopy imaging of a standard silicon calibration grating at line rates up to several kHz.