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Sample records for high-resolution optical recording

  1. High-Resolution CRT Optical Film Recorder Incorporating an Optical Feedback Exposure Control.

    PubMed

    Nix, L A; Ley, G S

    1972-05-01

    A high-resolution CRT optical film recorder incorporating an optical exposure control system is described. The recorder incorporates provisions for a highly nonlinear writing rate of up to 7 to 1 that make it uniquely suited for such applications as side-look radar or sonar. Provisions are made for spot shaping permitting line fill-in between scan lines spaced up to ten spot sizes apart. The recorder achieves a linear gray scale having sixteen equal density steps for a wide range of sweep times by means of a brightness feedback loop that automatically corrects for such problems as phosphor saturation, phosphor noise, nonlinear CRT grid transfer characteristics, variation in cathode emission, and tube aging in conjunction with film gamma correction circuitry.

  2. High-resolution non-contact measurement of the electrical activity of plants in situ using optical recording

    PubMed Central

    Zhao, Dong-Jie; Chen, Yang; Wang, Zi-Yang; Xue, Lin; Mao, Tong-Lin; Liu, Yi-Min; Wang, Zhong-Yi; Huang, Lan

    2015-01-01

    The limitations of conventional extracellular recording and intracellular recording make high-resolution multisite recording of plant bioelectrical activity in situ challenging. By combining a cooled charge-coupled device camera with a voltage-sensitive dye, we recorded the action potentials in the stem of Helianthus annuus and variation potentials at multiple sites simultaneously with high spatial resolution. The method of signal processing using coherence analysis was used to determine the synchronization of the selected signals. Our results provide direct visualization of the phloem, which is the distribution region of the electrical activities in the stem and leaf of H. annuus, and verify that the phloem is the main action potential transmission route in the stems of higher plants. Finally, the method of optical recording offers a unique opportunity to map the dynamic bioelectrical activity and provides an insight into the mechanisms of long-distance electrical signal transmission in higher plants. PMID:26333536

  3. Holographic high-resolution endoscopic image recording

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.

    1991-03-01

    Endoscopic holography or endoholography combines the features of endoscopy and holography. The purpose of endoholographic imaging is to provide the physician with a unique means of extending diagnosis by providing a life-like record of tissue. Endoholographic recording will provide means for microscopic examination of tissue and in some cases may obviate the need to excise specimens for biopsy. In this method holograms which have the unique properties of three-dimensionality large focal depth and high resolution are made with a newly designed endoscope. The endoscope uses a single-mode optical fiber for illumination and single-beam reflection holograms are recorded in close contact with the tissue at the distal end of the endoscope. The holograms are viewed under a microscope. By using the proper combinations of dyes for staining specific tissue types with various wavelengths of laser illumination increased contrast on the cellular level can be obtained. Using dyes such as rose bengal in combination with the 514. 5 nm line of an argon ion laser and trypan blue or methylene blue with the 647. 1 nm line of a krypton ion laser holograms of the stained colon of a dog showed the architecture of the colon''s columnar epithelial cells. It is hoped through chronological study using this method in-vivo an increased understanding of the etiology and pathology of diseases such as Crohn''s diseases colitis proctitis and several different forms of cancer will help

  4. High resolution optical DNA mapping

    NASA Astrophysics Data System (ADS)

    Baday, Murat

    Many types of diseases including cancer and autism are associated with copy-number variations in the genome. Most of these variations could not be identified with existing sequencing and optical DNA mapping methods. We have developed Multi-color Super-resolution technique, with potential for high throughput and low cost, which can allow us to recognize more of these variations. Our technique has made 10--fold improvement in the resolution of optical DNA mapping. Using a 180 kb BAC clone as a model system, we resolved dense patterns from 108 fluorescent labels of two different colors representing two different sequence-motifs. Overall, a detailed DNA map with 100 bp resolution was achieved, which has the potential to reveal detailed information about genetic variance and to facilitate medical diagnosis of genetic disease.

  5. Indicators and optical configuration for simultaneous high-resolution recording of membrane potential and intracellular calcium using laser scanning microscopy.

    PubMed

    Bullen, A; Saggau, P

    1998-10-01

    The instrumental design and experimental conditions for high-speed, simultaneous optical recording of membrane potential and intracellular Ca2+ with subcellular resolution are presented. This method employs an extended version of a high-speed, random-access, laser-scanning fluorescence microscope designed to record fast physiological signals from small neuronal structures with high spatiotemporal resolution (Bullen, Patel, Saggau, Biophys J 73:477-491, 1997). With this instrument, imaging and optical recording functions are conducted separately allowing frame rates up to 3 kHz. Individual scanning points are selected interactively from a reference image collected with differential interference contrast (DIC) optics. At each recording site, fluorescence from two indicators is measured simultaneously by independent photodetectors. To optimize signal strength, spectral separation and the achievable signal-to-noise ratio, several combinations of voltage-sensitive dye, Ca2+ indicator and optical elements (dichroic mirrors, filters, etc.) were considered. The best results were achieved from the combination of the intracellular voltage-sensitive dye Di-2-ANEPEQ and the Ca2+ indicator Calcium Green-1. These indicators have overlapping absorption spectra allowing simultaneous excitation with a single laser line (488 nm). Spectral separation of the fluorescence from these two indicators was accomplished using a secondary dichroic mirror (DCLP580) and emission filters (535/45 and OG590). Representative records obtained with this instrument and this combination of indicators demonstrate the feasibility of simultaneous high fidelity measurements of membrane potential and intracellular Ca2+ from the same point at high spatial (2 micrometer) and temporal (

  6. High resolution wavefront measurement of aspheric optics

    NASA Astrophysics Data System (ADS)

    Erichsen, I.; Krey, S.; Heinisch, J.; Ruprecht, A.; Dumitrescu, E.

    2008-08-01

    With the recently emerged large volume production of miniature aspheric lenses for a wide range of applications, a new fast fully automatic high resolution wavefront measurement instrument has been developed. The Shack-Hartmann based system with reproducibility better than 0.05 waves is able to measure highly aspheric optics and allows for real time comparison with design data. Integrated advanced analysis tools such as calculation of Zernike coefficients, 2D-Modulation Transfer Function (MTF), Point Spread Function (PSF), Strehl-Ratio and the measurement of effective focal length (EFL) as well as flange focal length (FFL) allow for the direct verification of lens properties and can be used in a development as well as in a production environment.

  7. Wide swath and high resolution optical imaging satellite of Japan

    NASA Astrophysics Data System (ADS)

    Katayama, Haruyoshi; Kato, Eri; Imai, Hiroko; Sagisaka, Masakazu

    2016-05-01

    The "Advanced optical satellite" (tentative name) is a follow-on mission from ALOS. Mission objectives of the advanced optical satellite is to build upon the existing advanced techniques for global land observation using optical sensors, as well as to promote data utilization for social needs. Wide swath and high resolution optical imager onboard the advanced optical satellite will extend the capabilities of earlier ALOS missions. The optical imager will be able to collect high-resolution (< 1 m) and wide-swath (70 km) images with high geo-location accuracy. This paper introduces a conceptual design of the advanced optical satellite.

  8. Optical alignment of high resolution Fourier transform spectrometers

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

    1980-01-01

    Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

  9. High resolution fiber optic interferometer: FY94 final report

    SciTech Connect

    Baldwin, D.P.; Zamzow, D.S.; D`Silva, A.P.

    1994-12-31

    Objective is a field, on-line high resolution spectrometer system capable of resolving the optical emission from actinide isotopes in an inductively coupled plasma. AOTF (acousto-optic tunable filter) and FFP (fiber optic Fabry-Perot) were combined in this spectrometer, using bulk optical materials. The AOTF-FFP system was tested on U-235/U-238 and RCRA metals. Future development is described; a commercialization plan is attached.

  10. 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

  11. 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. PMID:9199810

  12. Optical multichannel analyzer techniques for high resolution optical spectroscopy

    SciTech Connect

    Chao, J.L.

    1980-06-01

    The development of optical multichannel analyzer techniques for UV/VIS spectroscopy is presented. The research focuses on the development of spectroscopic techniques for measuring high resolution spectral lineshape functions from the exciton phosphorescence in H/sub 2/-1,2,4,5-tetrachlorobenzene. It is found that the temperature dependent frequency shifts and widths confirm a theoretical model based on an exchange theory. The exchange of low energy phonon modes which couple with excited state exciton transitions is shown to display the proper temperature dependent behavior. In addition to the techniques for using the optical multichannel analyzer (OMA) to perform low light level target integration, the use of the OMA for capturing spectral information in transient pulsed laser applications is discussed. An OMP data acquisition system developed for real-time signal processng is described. Both hardware and software interfacing considerations for control and data acquisition by a microcomputer are described. The OMA detector is described in terms of the principles behind its photoelectron detection capabilities and its design is compared with other optoelectronic devices.

  13. Alternative high-resolution lithographic technologies for optical applications

    NASA Astrophysics Data System (ADS)

    Zeitner, Uwe D.; Weichelt, Tina; Bourgin, Yannick; Kinder, Robert

    2016-03-01

    Modern optical applications have special demands on the lithographic fabrication technologies. This relates to the lateral shape of the structures as well as to their three dimensional surface profile. On the other hand optical nano-structures are often periodic which allows for the use of dedicated lithographic exposure principles. The paper briefly reviews actual developments in the field of optical nano-structure generation. Special emphasis will be given to two technologies: electron-beam lithography based on a flexible cell-projection method and the actual developments in diffractive mask aligner lithography. Both offer a cost effective fabrication alternative for high resolution structures or three-dimensional optical surface profiles.

  14. Adaptive optics with pupil tracking for high resolution retinal imaging.

    PubMed

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  15. A high-resolution record of Greenland mass balance

    NASA Astrophysics Data System (ADS)

    McMillan, Malcolm; Leeson, Amber; Shepherd, Andrew; Briggs, Kate; Armitage, Thomas W. K.; Hogg, Anna; Kuipers Munneke, Peter; Broeke, Michiel; Noël, Brice; Berg, Willem Jan; Ligtenberg, Stefan; Horwath, Martin; Groh, Andreas; Muir, Alan; Gilbert, Lin

    2016-07-01

    We map recent Greenland Ice Sheet elevation change at high spatial (5 km) and temporal (monthly) resolution using CryoSat-2 altimetry. After correcting for the impact of changing snowpack properties associated with unprecedented surface melting in 2012, we find good agreement (3 cm/yr bias) with airborne measurements. With the aid of regional climate and firn modeling, we compute high spatial and temporal resolution records of Greenland mass evolution, which correlate (R = 0.96) with monthly satellite gravimetry and reveal glacier dynamic imbalance. During 2011-2014, Greenland mass loss averaged 269 ± 51 Gt/yr. Atmospherically driven losses were widespread, with surface melt variability driving large fluctuations in the annual mass deficit. Terminus regions of five dynamically thinning glaciers, which constitute less than 1% of Greenland's area, contributed more than 12% of the net ice loss. This high-resolution record demonstrates that mass deficits extending over small spatial and temporal scales have made a relatively large contribution to recent ice sheet imbalance.

  16. High-resolution extended source optical coherence tomography.

    PubMed

    Yu, Xiaojun; Liu, Xinyu; Chen, Si; Luo, Yuemei; Wang, Xianghong; Liu, Linbo

    2015-10-01

    High resolution optical coherence tomography (OCT) is capable of providing detailed tissue microstructures that are critical for disease diagnosis, yet its sensitivity is usually degraded since the system key components are typically not working at their respective center wavelengths. We developed a novel imaging system that achieves enhanced sensitivity without axial resolution degradation by the use of a spectrally encoded extended source (SEES) technique; it allows larger sample power without exceeding the maximum permissible exposure (MPE). In this study, we demonstrate a high-resolution extended source (HRES) OCT system, which is capable of providing a transverse resolution of 4.4 µm and an axial resolution of 2.1 µm in air with the SEES technique. We first theoretically show a sensitivity advantage of 6-dB of the HRES-OCT over that of its point source counterpart using numerical simulations, and then experimentally validate the applicability of the SEES technique to high-resolution OCT (HR-OCT) by comparing the HRES-OCT with an equivalent point-source system. In the HRES-OCT system, a dispersive prism was placed in the infinity space of the sample arm optics to spectrally extend the visual angle (angular subtense) of the light source to 10.3 mrad. This extended source allowed ~4 times larger MPE than its point source counterpart, which results in an enhancement of ~6 dB in sensitivity. Specifically, to solve the unbalanced dispersion between the sample and the reference arm optics, we proposed easy and efficient methods for system calibration and dispersion correction, respectively. With a maximum scanning speed reaching up to 60K A-lines/s, we further conducted imaging experiments with HRES-OCT using the human fingertip in vivo and the swine eye tissues ex vivo. Results demonstrate that the HRES-OCT is able to achieve significantly larger penetration depth than its conventional point source OCT counterpart.

  17. All-Optical Ultrasound Transducers for High Resolution Imaging

    NASA Astrophysics Data System (ADS)

    Sheaff, Clay Smith

    High frequency ultrasound (HFUS) has increasingly been used within the past few decades to provide high resolution (< 200 mum) imaging in medical applications such as endoluminal imaging, intravascular imaging, ophthalmology, and dermatology. The optical detection and generation of HFUS using thin films offers numerous advantages over traditional piezoelectric technology. Circumvention of an electronic interface with the device head is one of the most significant given the RF noise, crosstalk, and reduced capacitance that encumbers small-scale electronic transducers. Thin film Fabry-Perot interferometers - also known as etalons - are well suited for HFUS receivers on account of their high sensitivity, wide bandwidth, and ease of fabrication. In addition, thin films can be used to generate HFUS when irradiated with optical pulses - a method referred to as Thermoelastic Ultrasound Generation (TUG). By integrating a polyimide (PI) film for TUG into an etalon receiver, we have created for the first time an all-optical ultrasound transducer that is both thermally stable and capable of forming fully sampled 2-D imaging arrays of arbitrary configuration. Here we report (1) the design and fabrication of PI-etalon transducers; (2) an evaluation of their optical and acoustic performance parameters; (3) the ability to conduct high-resolution imaging with synthetic 2-D arrays of PI-etalon elements; and (4) work towards a fiber optic PI-etalon for in vivo use. Successful development of a fiber optic imager would provide a unique field-of-view thereby exposing an abundance of prospects for minimally-invasive analysis, diagnosis, and treatment of disease.

  18. Optical Histology: High-Resolution Visualization of Tissue Microvasculature

    NASA Astrophysics Data System (ADS)

    Moy, Austin Jing-Ming

    Mammalian tissue requires the delivery of nutrients, growth factors, and the exchange of oxygen and carbon dioxide gases to maintain normal function. These elements are delivered by the blood, which travels through the connected network of blood vessels, known as the vascular system. The vascular system consists of large feeder blood vessels (arteries and veins) that are connected to the small blood vessels (arterioles and venules), which in turn are connected to the capillaries that are directly connected to the tissue and facilitate gas exchange and nutrient delivery. These small blood vessels and capillaries make up an intricate but organized network of blood vessels that exist in all mammalian tissues known as the microvasculature and are very important in maintaining the health and proper function of mammalian tissue. Due to the importance of the microvasculature in tissue survival, disruption of the microvasculature typically leads to tissue dysfunction and tissue death. The most prevalent method to study the microvasculature is visualization. Immunohistochemistry (IHC) is the gold-standard method to visualize tissue microvasculature. IHC is very well-suited for highly detailed interrogation of the tissue microvasculature at the cellular level but is unwieldy and impractical for wide-field visualization of the tissue microvasculature. The objective my dissertation research was to develop a method to enable wide-field visualization of the microvasculature, while still retaining the high-resolution afforded by optical microscopy. My efforts led to the development of a technique dubbed "optical histology" that combines chemical and optical methods to enable high-resolution visualization of the microvasculature. The development of the technique first involved preliminary studies to quantify optical property changes in optically cleared tissues, followed by development and demonstration of the methodology. Using optical histology, I successfully obtained high

  19. High resolution analytical transmission electron microscopy of magnetic recording media

    NASA Astrophysics Data System (ADS)

    Risner, Juliet Danielle

    Since the invention of the hard disk drive in 1954, the density of bits per disk has increased exponentially. This trend is partly due to improvements to the magnetic recording media. In current hard disks, each bit is approximately 0.04 mum in its smallest dimension and comprises ˜100 hexagonal close packed Co-alloy magnetic grains. These grains have magnetic "easy" axes oriented longitudinally, or parallel to the film plane. Future recording media have easy axes oriented perpendicular to the film plane. Perpendicular media are expected to provide continued increases in storage density above the limit of longitudinal media. Quantum-mechanical exchange coupling between magnetic grains degrades the signal-to-noise ratio (SNR) and limits storage density in both media types. Controlling exchange coupling is possible by creating nonmagnetic grain boundaries which compositionally isolate the magnetic grains. High-resolution analytical transmission electron microscopy (TEM) is required to study these media because of their nano-scale grains and grain boundaries. Examining the microstructure and elemental distribution in these films at near atomic level is paramount to understanding their magnetic performance. The microstructure and elemental distribution in longitudinal and perpendicular media were examined using high resolution analytical TEM techniques, such as energy-filtered TEM (EFTEM), energy-dispersive x-ray spectroscopy (EDS) using a 1.5 nm electron probe, and spectrum imaging with a scanning TEM. These techniques successfully determined how grain boundary Cr segregation varies with grain orientation in longitudinal media. Boundaries misoriented by 0° and 90° commonly occur and were found to have minimal Cr segregation, which limits storage density improvement in these media. Analytical TEM techniques applied to oxygen-enriched perpendicular media, fabricated using different deposition methods, effectively related microstructure and composition to magnetic

  20. Precision glass molding of high-resolution diffractive optical elements

    NASA Astrophysics Data System (ADS)

    Prater, Karin; Dukwen, Julia; Scharf, Toralf; Herzig, Hans P.; Plöger, Sven; Hermerschmidt, Andreas

    2016-04-01

    The demand of high resolution diffractive optical elements (DOE) is growing. Smaller critical dimensions allow higher deflection angles and can fulfill more demanding requirements, which can only be met by using electron-beam lithography. Replication techniques are more economical, since the high cost of the master can be distributed among a larger number of replicas. The lack of a suitable mold material for precision glass molding has so far prevented an industrial use. Glassy Carbon (GC) offers a high mechanical strength and high thermal strength. No anti-adhesion coatings are required in molding processes. This is clearly an advantage for high resolution, high aspect ratio microstructures, where a coating with a thickness between 10 nm and 200 nm would cause a noticeable rounding of the features. Electron-beam lithography was used to fabricate GC molds with highest precision and feature sizes from 250 nm to 2 μm. The master stamps were used for precision glass molding of a low Tg glass L-BAL42 from OHARA. The profile of the replicated glass is compared to the mold with the help of SEM images. This allows discussion of the max. aspect-ratio and min. feature size. To characterize optical performances, beamsplitting elements are fabricated and their characteristics were investigated, which are in excellent agreement to theory.

  1. Thermal refocusing method for spaceborne high-resolution optical imagers.

    PubMed

    Selımoglu, Ozgur; Ekinci, Mustafa; Karcı, Ozgur

    2016-05-20

    We describe the design of a thermal refocusing method for spaceborne high-resolution imagers where Korsch optical design is usually implemented. The secondary mirror is made of aluminum, a high thermal expansion coefficient material, instead of conventional zero-expansion glass ceramics. In this way, the radius of the curvature can be controlled by means of temperature change of the mirror. Change in the radius of curvature also changes the effective focal length of the camera which is used for compensation of the defocus that occurred in space. We show that the 30 μm despace of the secondary mirror in the optical system can be compensated by an ∼10°C temperature change of the mirror while the image quality is maintained. PMID:27411138

  2. High-Resolution Mammography Detector Employing Optical Switching Readout

    NASA Astrophysics Data System (ADS)

    Irisawa, Kaku; Kaneko, Yasuhisa; Yamane, Katsutoshi; Sendai, Tomonari; Hosoi, Yuichi

    Conceiving a new detector structure, FUJIFILM Corporation has successfully put its invention of an X-ray detector employing "Optical Switching" into practical use. Since Optical Switching Technology allows an electrode structure to be easily designed, both high resolution of pixel pitch and low electrical noise readout have been achieved, which have consequently realized the world's smallest pixel size of 50×50 μm2 from a Direct-conversion FPD system as well as high DQE. The digital mammography system equipped with this detector enables to acquire high definition images while maintaining granularity. Its outstanding feature is to be able to acquire high-precision images of microcalcifications which is an important index in breast examination.

  3. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  4. Gemini high-resolution optical spectrograph conceptual design

    NASA Astrophysics Data System (ADS)

    Szeto, Kei; McConnachie, Alan; Anthony, André; Bohlender, David; Crampton, David; Desaulniers, Pierre; Dunn, Jennifer; Hardy, Tim; Hill, Alexis; Monin, Dmitry; Pazder, John; Schwab, Christian; Spano, Paola; Starkenburg, Else; Thibault, Simon; Walker, Gordon; Venn, Kim; Zhang, Hu

    2012-09-01

    A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility for the entire 340 - 950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R = 90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study.

  5. High Resolution Optical and NIR Spectra of HBC 722

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s‑1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s‑1. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R⊙, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models. Based on observations obtained with the Hobby–Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  6. HIGH RESOLUTION OPTICAL AND NIR SPECTRA OF HBC 722

    SciTech Connect

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il E-mail: sunkyung@khu.ac.kr E-mail: wdc@astro.as.utexas.edu E-mail: sanggak@kywa.or.kr

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby–Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s{sup −1} while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s{sup −1}. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R{sub ⊙}, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models.

  7. High Resolution Optical and NIR Spectra of HBC 722

    NASA Astrophysics Data System (ADS)

    Lee, Jeong-Eun; Park, Sunkyung; Green, Joel D.; Cochran, William D.; Kang, Wonseok; Lee, Sang-Gak; Sung, Hyun-Il

    2015-07-01

    We present the results of high resolution (R ≥ 30,000) optical and near-IR spectroscopic monitoring observations of HBC 722, a recent FU Orionis object that underwent an accretion burst in 2010. We observed HBC 722 in the optical/near-IR with the Bohyunsan Optical Echelle Spectrograph, Hobby-Eberly Telescope-HRS, and Immersion Grating Infrared Spectrograph, at various points in the outburst. We found atomic lines with strongly blueshifted absorption features or P Cygni profiles, both evidence of a wind driven by the accretion. Some lines show a broad double-peaked absorption feature, evidence of disk rotation. However, the wind-driven and disk-driven spectroscopic features are anti-correlated in time; the disk features became strong as the wind features disappeared. This anti-correlation might indicate that the rebuilding of the inner disk was interrupted by the wind pressure during the first 2 years. The half-width at half-depth of the double-peaked profiles decreases with wavelength, indicative of the Keplerian rotation; the optical spectra with the disk feature are fitted by a G5 template stellar spectrum convolved with a rotation velocity of 70 km s-1 while the near-IR disk features are fitted by a K5 template stellar spectrum convolved with a rotation velocity of 50 km s-1. Therefore, the optical and near-IR spectra seem to trace the disk at 39 and 76 R⊙, respectively. We fit a power-law temperature distribution in the disk, finding an index of 0.8, comparable to optically thick accretion disk models. Based on observations obtained with the Hobby-Eberly Telescope, which is a joint project of the University of Texas at Austin, the Pennsylvania State University, Stanford University, Ludwig-Maximilians-Universität München, and Georg-August-Universität Göttingen.

  8. Large Field, High Resolution Full-Field Optical Coherence Tomography

    PubMed Central

    Assayag, Osnath; Antoine, Martine; Sigal-Zafrani, Brigitte; Riben, Michael; Harms, Fabrice; Burcheri, Adriano; Grieve, Kate; Dalimier, Eugénie; Le Conte de Poly, Bertrand; Boccara, Claude

    2014-01-01

    We present a benchmark pilot study in which high-resolution Full-Field Optical Coherence Tomography (FF-OCT) was used to image human breast tissue and is evaluated to assess its ability to aid the pathologist’s management of intra-operative diagnoses. FF-OCT imaging safety was investigated and agreement between FF-OCT and routinely prepared histopathological images was evaluated. The compact setup used for this study provides 1 µm3 resolution and 200 µm imaging depth, and a 2.25 cm2 specimen is scanned in about 7 minutes. 75 breast specimens were imaged from 22 patients (21 women, 1 man) with a mean age of 58 (range: 25-83). Pathologists blind diagnosed normal/benign or malignant tissue based on FF-OCT images alone, diagnosis from histopathology followed for comparison. The contrast in the FF-OCT images is generated by intrinsic tissue scattering properties, meaning that no tissue staining or preparation is required. Major architectural features and tissue structures of benign breast tissue, including adipocytes, fibrous stroma, lobules and ducts were characterized. Subsequently, features resulting from pathological modification were characterized and a diagnosis decision tree was developed. Using FF-OCT images, two breast pathologists were able to distinguish normal/benign tissue from lesional with a sensitivity of 94% and 90%, and specificity of 75% and 79% respectively. PMID:24000981

  9. Urban Ecosystems from Spaceborne High-Resolution Optical Data

    NASA Astrophysics Data System (ADS)

    Haas, Jan; Jacob, Alexander; Ban, Yifang

    2014-11-01

    The potential of high-resolution optical satellite images for mapping of ecologically important urban space is investigated in this study. Both a GeoEye-1 and a Landsat 8 scene over central Shanghai were first segmented by two different algorithms and then classified into seven urban classes by SVM. Shadows in the pan-sharpened GeoEye-1 image were masked out and replaced by the corresponding pan-sharpened classified Landsat 8 image. Largest confusions occurred between sealed and permeable but non-vegetated surfaces, and between low-rise residential and high-rise commercial buildings. Based on the classification result, ecosystem service balances, supply and demand was modelled for each particular land cover class. Classification accuracies of 88% and 91% could be reached, indicating the suitability of the underlying data and method for this application domain. The KTH-SEG segmentation algorithm slightly outperformed the one implemented in eCognition. The highest supply of ecosystem services was found in water bodies whereas high-rise built-up areas revealed largest demands.

  10. PEPSI, the High-Resolution Optical-IR Spectrograph for the LBT

    NASA Astrophysics Data System (ADS)

    Andersen, Michael; Strassmeier, Klaus; Hoffman, Axel; Woche, Manfred; Spano, Paolo

    PEPSI is a high resolution fibre feed optical-IR polarimetric echelle spectrograph for the Large Binocular Telescope (LBT). PEPSI utilizes the two 8.4m LBT apertures to simultaneously record four polarization states at a resolution of 120.000. The extension of the coverage towards the IR is mainly motivated by the larger Zeeman splitting of IR lines, which would allow to study weaker/fainter magnetic structures on stars. The two optical arms, which also have an integral light mode with R up to 300.000, are under construction, while the IR arm is being designed.

  11. Comparing Event-records of cryospheric change to high-resolution climate records

    NASA Astrophysics Data System (ADS)

    Schaefer, J. M.; Denton, G.; Putnam, A. E.; Kaplan, M. R.; Barrell, D.; Schluechter, C.; Rupper, S.; Finkel, R. C.; Schwartz, R.

    2012-12-01

    Evaluation of ongoing Cryospheric Change is a forefront challenge of earth sciences, because it directly impacts societies by sea level rise and changing river run-off pattern in densely populated areas. Robust predictions of future cryospheric change require quantitative understanding of the coupling between the climate and cryosphere systems. One promising approach to do so is to compare paleo-climate and paleo-cryosphere records. However, the terrestrial cryospheric record, including morphologies such as moraines and proglacial bedrock, represents an 'event record' that is by definition non-continuous. The most important climate proxy records such as polar ice-cores, marine sediment cores and speleothems are continuous, high-resolution proxy records. Meaningful comparison of the two requires detailed and accurate chronologies of the cryospheric record. Over the last years, the sensitivity of the method of surface exposure dating has considerably improved, increasing precision and size of data set. Now, we are in the position to compare, geomorphic records of former glacier and ice-sheet positions with continuous and high resolution climate records, and in turn, perform the experiment described above. Here we will compare extensive mountain glacier moraine chronologies from both hemispheres with relevant climate records, including tree-ring records, ice core proxy and gas records, and marine sediment records. We show that glacier fluctuations in New Zealand show remarkable general consistency to summer temperature and atmospheric greenhouse gas records, but also find second order distinctions between different glacier fluctuation records and the climate records on shorter time-scales. We focus on the time periods of (i) the last ice age termination and subsequent deglaciation (20-10 ka) and (ii) the late Holocene, including the last millennium and the Little Ice Age Period (CE 1300-1850).

  12. Special issue on high-resolution optical imaging

    NASA Astrophysics Data System (ADS)

    Smith, Peter J. S.; Davis, Ilan; Galbraith, Catherine G.; Stemmer, Andreas

    2013-09-01

    The pace of development in the field of advanced microscopy is truly breath-taking, and is leading to major breakthroughs in our understanding of molecular machines and cell function. This special issue of Journal of Optics draws attention to a number of interesting approaches, ranging from fluorescence and imaging of unlabelled cells, to computational methods, all of which are describing the ever increasing detail of the dynamic behaviour of molecules in the living cell. This is a field which traditionally, and currently, demonstrates a marvellous interplay between the disciplines of physics, chemistry and biology, where apparent boundaries to resolution dissolve and living cells are viewed in ever more clarity. It is fertile ground for those interested in optics and non-conventional imaging to contribute high-impact outputs in the fields of cell biology and biomedicine. The series of articles presented here has been selected to demonstrate this interdisciplinarity and to encourage all those with a background in the physical sciences to 'dip their toes' into the exciting and dynamic discoveries surrounding cell function. Although single molecule super-resolution microscopy is commercially available, specimen preparation and interpretation of single molecule data remain a major challenge for scientists wanting to adopt the techniques. The paper by Allen and Davidson [1] provides a much needed detailed introduction to the practical aspects of stochastic optical reconstruction microscopy, including sample preparation, image acquisition and image analysis, as well as a brief description of the different variants of single molecule localization microscopy. Since super-resolution microscopy is no longer restricted to three-dimensional imaging of fixed samples, the review by Fiolka [2] is a timely introduction to techniques that have been successfully applied to four-dimensional live cell super-resolution microscopy. The combination of multiple high-resolution techniques

  13. Special issue on high-resolution optical imaging

    NASA Astrophysics Data System (ADS)

    Smith, Peter J. S.; Davis, Ilan; Galbraith, Catherine G.; Stemmer, Andreas

    2013-09-01

    The pace of development in the field of advanced microscopy is truly breath-taking, and is leading to major breakthroughs in our understanding of molecular machines and cell function. This special issue of Journal of Optics draws attention to a number of interesting approaches, ranging from fluorescence and imaging of unlabelled cells, to computational methods, all of which are describing the ever increasing detail of the dynamic behaviour of molecules in the living cell. This is a field which traditionally, and currently, demonstrates a marvellous interplay between the disciplines of physics, chemistry and biology, where apparent boundaries to resolution dissolve and living cells are viewed in ever more clarity. It is fertile ground for those interested in optics and non-conventional imaging to contribute high-impact outputs in the fields of cell biology and biomedicine. The series of articles presented here has been selected to demonstrate this interdisciplinarity and to encourage all those with a background in the physical sciences to 'dip their toes' into the exciting and dynamic discoveries surrounding cell function. Although single molecule super-resolution microscopy is commercially available, specimen preparation and interpretation of single molecule data remain a major challenge for scientists wanting to adopt the techniques. The paper by Allen and Davidson [1] provides a much needed detailed introduction to the practical aspects of stochastic optical reconstruction microscopy, including sample preparation, image acquisition and image analysis, as well as a brief description of the different variants of single molecule localization microscopy. Since super-resolution microscopy is no longer restricted to three-dimensional imaging of fixed samples, the review by Fiolka [2] is a timely introduction to techniques that have been successfully applied to four-dimensional live cell super-resolution microscopy. The combination of multiple high-resolution techniques

  14. Holographic recording aspects of high-resolution Bayfol HX photopolymer

    NASA Astrophysics Data System (ADS)

    Berneth, Horst; Bruder, Friedrich K.; Fäcke, Thomas; Hagen, Rainer; Hönel, Dennis; Jurbergs, David; Rölle, Thomas; Weiser, Marc-Stephan

    2011-02-01

    We have been developing a new class of recording materials for volume holography, offering the advantages of full color recording and depth tuning without any chemical or thermal processing, combined with low shrinkage and detuning. These photopolymers are based on the two-chemistry concept in which the writing chemistry is dissolved in a preformed polymeric network. This network gives the necessary mechanical stability to the material prior to recording. In this paper we describe several aspects of holographic recording into Bayfol® HX which are beneficial for its effective use and discuss them within a more elaborate reaction-diffusion model. Inhibition phenomena and the influence of precure are studied within this model and are investigated experimentally for single hologram recording and angular multiplexed hologram recordings. Also the dark reaction after the exposure period and the minimum allowable waiting time for full hologram formation are addressed. The proper understanding of these phenomena is important for the optimal usage of these new materials, in for example step-and-repeat mass production of holograms.

  15. High-resolution optical spectroscopy of Plaskett's star

    NASA Astrophysics Data System (ADS)

    Linder, N.; Rauw, G.; Martins, F.; Sana, H.; De Becker, M.; Gosset, E.

    2008-10-01

    Context: Plaskett's star (HD 47 129) is a very massive O + O binary that belongs to the Mon OB2 association. Previous work suggests that this system displays the Struve-Sahade effect although the measurements of the secondary radial velocities are very difficult and give controversial results. Both components have powerful stellar winds that collide and produce a strong X-ray emission. Aims: Our aim is to study the physical parameters of this system in detail and to investigate the relation between its spectral properties and its evolutionary status. Methods: We present here analysis of an extensive set of high-resolution optical spectra of HD 47 129. We used a disentangling method to separate the individual spectra of each star. We derived a new orbital solution and discuss the spectral classification of both components. A Doppler tomography technique applied to the emission lines Hα and He II λ 4686 yields a Doppler map that illustrates the wind interactions in the system. Finally, an atmosphere code is used to determine the different chemical abundances of the system components and the wind parameters. Results: HD 47 129 appears to be an O8 III/I + O7.5 III binary system in a post RLOF evolutionary stage, where matter has been transferred from the primary to the secondary star. The He overabundance of the secondary supports this scenario. In addition, the N overabundance and C underabundance of the primary component confirm previous results based on X-ray spectroscopy and indicate that the primary is an evolved massive star. We also determined a new orbital solution, with MP sin^3i = 45.4 ± 2.4 M⊙ and MS sin^3i = 47.3 ± 0.3 M⊙. Furthermore, the secondary star has a high rotational velocity (v sin i ˜ 300 km s-1) that deforms its surface, leading to a non-uniform distribution in effective temperature. This could explain the variations in the equivalent widths of the secondary lines with phase. We suggest that the wind of the secondary star is confined

  16. High resolution mesospheric sodium properties for adaptive optics applications

    NASA Astrophysics Data System (ADS)

    Pfrommer, T.; Hickson, P.

    2014-05-01

    Context. The performance of laser guide star adaptive optics (AO) systems for large optical and infrared telescopes is affected by variability of the sodium layer, located at altitudes between 80 and 120 km in the upper mesosphere and lower thermosphere. The abundance and density structure of the atomic sodium found in this region is subject to local and global weather effects, planetary and gravity waves and magnetic storms, and is variable on time scales down to tens of milliseconds, a range relevant to AO. Aims: It is therefore important to characterize the structure and dynamical evolution of the sodium region on small, as well as large spatial and temporal scales. Parameters of particular importance for AO are the mean sodium altitude, sodium layer width and the temporal power spectrum of the centroid altitude. Methods: We have conducted a three-year campaign employing a high-resolution lidar system installed on the 6-m Large Zenith Telescope (LZT) located near Vancouver, Canada. During this period, 112 nights of useful data were obtained. Results: The vertical density profile of atomic sodium shows remarkable structure and variability. Smooth Gaussian-shaped profiles rarely occur. Multiple internal layers are frequently found. These layers often have sharp lower edges, with scale heights of just a few hundred meters, and tend to drift downwards at a typical rate of one kilometer every two to three hours. Individual layers can persist for many hours, but their density and internal structure can be highly variable. Sporadic layers are seen reaching peak densities several times the average, often in just a few minutes. Coherent vertical oscillations are often found, typically extending over tens of kilometers in altitude. Regions of turbulence are evident and Kelvin-Helmholtz instability are sometimes seen. The mean value of the centroid altitude is found to be 90.8 ± 0.1 km. The sodium layer width was determined by computing the altitude range that contains a

  17. Adaptive optics technology for high-resolution retinal imaging.

    PubMed

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2012-12-27

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging.

  18. Adaptive Optics Technology for High-Resolution Retinal Imaging

    PubMed Central

    Lombardo, Marco; Serrao, Sebastiano; Devaney, Nicholas; Parravano, Mariacristina; Lombardo, Giuseppe

    2013-01-01

    Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effects of optical aberrations. The direct visualization of the photoreceptor cells, capillaries and nerve fiber bundles represents the major benefit of adding AO to retinal imaging. Adaptive optics is opening a new frontier for clinical research in ophthalmology, providing new information on the early pathological changes of the retinal microstructures in various retinal diseases. We have reviewed AO technology for retinal imaging, providing information on the core components of an AO retinal camera. The most commonly used wavefront sensing and correcting elements are discussed. Furthermore, we discuss current applications of AO imaging to a population of healthy adults and to the most frequent causes of blindness, including diabetic retinopathy, age-related macular degeneration and glaucoma. We conclude our work with a discussion on future clinical prospects for AO retinal imaging. PMID:23271600

  19. On-demand optical immobilization of Caenorhabditis elegans for high-resolution imaging and microinjection.

    PubMed

    Hwang, Hyundoo; Krajniak, Jan; Matsunaga, Yohei; Benian, Guy M; Lu, Hang

    2014-09-21

    This paper describes a novel selective immobilization technique based on optical control of the sol-gel transition of thermoreversible Pluronic gel, which provides a simple, versatile, and biocompatible approach for high-resolution imaging and microinjection of Caenorhabditis elegans.

  20. Ultra-high resolution spectroscopy of optical frequency combs

    NASA Astrophysics Data System (ADS)

    Schneider, Thomas; Preußler, Stefan

    2016-03-01

    The precision, versatility and broad bandwidth of frequency combs are the basis of many different applications from the microwave via the millimeter and THz up to the optical range of the electromagnetic spectrum. Optical frequency combs can be used for the new definition of physical constants, for high-precision metrology and spectroscopy and for ultrahigh bitrate data communications, for instance. Besides the stability and the bandwidth, the most important parameters of a frequency comb are the free spectral range ,as well as the linewidth and amplitude of the single comb lines. A conventional grating based optical spectrometer can easily measure the bandwidth of the comb. However, it fails for the measurement of all other comb parameters, if the comb is generated by a mode-locked fiber laser for instance. Here we present a proof-of-concept setup for an optical spectrometer with a resolution in the kHz-range and first measurements of the free spectral range, linewidth and amplitude of a comb source. The spectrometer is based on the combination of optical heterodyning with the polarization pulling effect of stimulated Brillouin scattering. As we will discuss, the maximum possible resolution is only restricted by the linewidth and stability of the used reference laser. Thus due to the stability of our laser used as local oscillator, our setup has a maximum resolution of around 5 kHz or 40 attometer, corresponding to 11 orders of magnitude compared to the center frequency of the comb of around 190 THz.

  1. High energy, high resolution X-ray optics

    NASA Technical Reports Server (NTRS)

    Weisskopf, Martin C.; Joy, Marshall; Kahn, Steven

    1990-01-01

    The scientific goals of X-ray astronomy are considered to evaluate the relative advantages of using classical Wolter-1 optics or using a different approach. The portion of the X-ray band over 10 keV is unexploited in the present X-ray optics technology, and focussing in this portion of the band is crucial because nonfocussed experiments are background limited. The basic design of 'hard' X-ray optics is described theoretically emphasizing the very small angles of incidence in the grazing-incidence optics. Optimization of the signal-to-noise ratio is found to occur at a finite angular resolution. In real applications, the effective area reduced by the efficiency of the two reflections is 80 percent at energies up to 40 keV, and the quality of the reflecting surface can be monitored to minimize scattering. Focussing optics are found to offer improvements in signal-to-noise as well as more effective scientific return because microelectronic focal-plane technology is employed.

  2. Bendable X-ray Optics for High Resolution Imaging

    NASA Technical Reports Server (NTRS)

    Gubarev, M.; Ramsey, B.; Kilaru, K.; Atkins, C.; Broadway, D.

    2014-01-01

    Current state-of the-art for x-ray optics fabrication calls for either the polishing of massive substrates into high-angular-resolution mirrors or the replication of thin, lower-resolution, mirrors from perfectly figured mandrels. Future X-ray Missions will require a change in this optics fabrication paradigm in order to achieve sub-arcsecond resolution in light-weight optics. One possible approach to this is to start with perfectly flat, light-weight surface, bend it into a perfect cone, form the desired mirror figure by material deposition, and insert the resulting mirror into a telescope structure. Such an approach is currently being investigated at MSFC, and a status report will be presented detailing the results of finite element analyses, bending tests and differential deposition experiments.

  3. On a possibility high resolution optical tomograph design

    NASA Astrophysics Data System (ADS)

    Khohlov, K. L.; Sokolov, V. K.

    2006-04-01

    An actual problem of the modern medicine is statement of the diagnosis of diseases of a thyroid gland of the person. Extreme sensitivity of this organ to a X-ray radiation and invasive to methods puts a problem about development of an optical tomograph of a high solution. For this purpose the method of coherent optical detection (CDT) in a combination to a posteriori handling can be used with the purpose of elimination of influence of a spread function of a figuring system.

  4. Optical system for high resolution spectrometer/monochromator

    DOEpatents

    Hettrick, M.C.; Underwood, J.H.

    1988-10-11

    An optical system for use in a spectrometer or monochromator employing a mirror which reflects electromagnetic radiation from a source to converge with same in a plane is disclosed. A straight grooved, varied-spaced diffraction grating receives the converging electromagnetic radiation from the mirror and produces a spectral image for capture by a detector, target or like receiver. 11 figs.

  5. Optical system for high resolution spectrometer/monochromator

    DOEpatents

    Hettrick, Michael C.; Underwood, James H.

    1988-01-01

    An optical system for use in a spectrometer or monochromator employing a mirror which reflects electromagnetic radiation from a source to converge with same in a plane. A straight grooved, varied-spaced diffraction grating receives the converging electromagnetic radiation from the mirror and produces a spectral image for capture by a detector, target or like receiver.

  6. High-resolution parallel optical coherence tomography in scattering samples

    NASA Astrophysics Data System (ADS)

    Laubscher, M.; Ducros, Mathieu G.; Karamata, Boris; Bourquin, Stephane; Lasser, Theo

    2001-11-01

    Parallel optical coherence tomography in scattering samples is demonstrated using a 58 by 58 smart-pixel detector array. A femtosecond mode-locked Ti:Sapphire laser in combination with a free space Michelson interferometer was employed to achieve 4micrometers longitudinal resolution and 9mm transverse resolution on a 260x260 micrometers 2 field of view. We imaged a resolution target covered by an intralipid solution with different scattering coefficients as well as onion cells.

  7. High Resolution Near-Infrared Imaging with Tip - Adaptive Optics.

    NASA Astrophysics Data System (ADS)

    Close, Laird Miller

    1995-01-01

    The development and design of the first operational tip-tilt Cassegrain secondary mirror are presented. This system, FASTTRAC, samples image motion at up to 50 Hz by tracking either infrared (m_{k } <=q 11) or visible (mR <=q 16) guide stars up to 30" and 90" away from the science target respectively. The Steward Observatory 2.3m or 1.5m telescope secondaries act as rapid tip-tilt mirrors to stabilize image motion (<=q0.1" rms;~5 Hz -3 dB frequency) based on the motion of the guide star. FASTTRAC obtains nearly diffraction-limited resolutions in seeing conditions where D/r_circ < 4 in agreement with theoretical expectations. FASTTRAC's unique ability to guide on infrared stars has allowed the first adaptively corrected images of the heavily extincted Galactic Center to be obtained. Over a hundred excellent (0.28" < FWHM < 0.6") images have been obtained of this region. These images do not detect any long term variations in the massive black hole candidate Sgr A*'s luminosity from June 1993 to September 1995. The average infrared magnitudes observed are K = 12.1 +/- 0.3, H = 13.7 +/- 0.3 and J = 16.6 +/- 0.4 integrated over 0.5" at the position of Sgr A*. No significant rapid periodicities were observed from Sgr A* for amplitudes >=q50% of the mean flux in the period range of 3-30 minutes. It is confirmed in the latest 0.28" FWHM image that there is 0.5" "bar" of emission running East-West at the position of Sgr A* as was earlier seen by Eckart et al. 1993. The observed fluxes are consistent with an inclined accretion disk around a ~1 times 10^6 M _odot black hole. However, they are also explained by a line of hot luminous (integrated luminosity of ~10^{3.5 -4.6}L_odot) central cluster stars positionally coincident with Sgr A* naturally explaining the observed 0.5" "bar". High-resolution images with FASTTRAC guiding on a faint (R = 16) visible guide star, combined with spectra from the MMT, have shown that IRAS FSC 10214 + 4724 (z = 2.28) gains its uniquely large

  8. High-resolution full-field spatial coherence gated optical tomography using monochromatic light source

    NASA Astrophysics Data System (ADS)

    Srivastava, Vishal; Nandy, Sreyankar; Singh Mehta, Dalip

    2013-09-01

    We demonstrate dispersion free, high-resolution full-field spatial coherence gated optical tomography using spatially incoherent monochromatic light source. Spatial coherence properties of light source were synthesized by means of combining a static diffuser and vibrating multi mode fiber bundle. Due to low spatial coherence of light source, the axial resolution of the system was achieved similar to that of conventional optical coherence tomography which utilizes low temporal coherence. Experimental results of fringe visibility versus optical path difference are presented for varying numerical apertures objective lenses. High resolution optically sectioned images of multilayer onion skin, and red blood cells are presented.

  9. Change detection in very high resolution multisensor optical images

    NASA Astrophysics Data System (ADS)

    Solano Correa, Yady T.; Bovolo, Francesca; Bruzzone, Lorenzo

    2014-10-01

    This work aims at developing an approach to the detection of changes in multisensor multitemporal VHR optical images. The main steps of the proposed method are: i) multisensor data homogenization; and ii) change detection in multisensor multitemporal VHR optical images. The proposed approach takes advantage of: the conversion to physical quantities suggested by Pacifici et. al.1 , the framework for the design of systems for change detection in VHR images presented by Bruzzone and Bovolo2 and the framework for unsupervised change detection presented by Bovolo and Bruzzone3. Multisensor data homogenization is achieved during pre-processing by taking into account differences in both radiometric and geometric dimensions. Whereas change detection was approached by extracting proper features from multisensor images such that they result to be comparable (at a given level of abstraction) even if extracted from images acquired by different sensors. In order to illustrate the results, a data set made up of a QuickBird and a WorldView-2 images - acquired in 2006 and 2010 respectively - over an area located in the Trentino region of Italy were used. However, the proposed approach is thought to be exportable to multitemporal images coming from passive sensors other than the two mentioned above. The experimental results obtained on the QuickBird and WorlView-2 image pair are accurate. Thus opening to further experiments on multitemporal images acquired by other sensors.

  10. High-resolution frequency domain second harmonic optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Su, Jianping; Tomov, I. V.; Jiang, Yi; Chen, Zhongping

    2007-02-01

    We used continuum generated in an 8.5 cm long fiber by a femtosecond Yb fiber laser to improve threefold the axial resolution of frequency domain SH-OCT to 12μm. The acquisition time was shortened by more than two orders of magnitude compared to time domain SH-OCT. The system was applied to image biological tissue of fish scales, pig leg tendon and rabbit eye sclera. Highly organized collagen fibrils can be visualized in the recorded images. Polarization dependence on second harmonic has been used to obtain polarization resolved images.

  11. High Resolution Optical Surface Investigation based on Heterodyne Interferometry

    NASA Astrophysics Data System (ADS)

    Spannagel, Ruven; Schuldt, Thilo; Braxmaier, Claus

    2012-07-01

    We present results on high precision optical profilometry for investigating reflecting surfaces with respect to surface properties such as structure, roughness, and waviness. Our metrology system is based on a highly symmetric heterodyne interferometer with a potential sensitivity at the picometer level. The profilometer is capable of scanning surfaces by actuating either the device under test (DUT), or the measurement laser beam of the interferometer. The current setup with DUT-actuation has a sensitivity of about 1 nm/ ? , and achives a measurement accuracy better than 5 nm at a measurement range of 100 μm with a lateral resolution of approximately 15 μm. Different profiles of various surfaces were measured and the reproducibility of the results have been demonstrated by measuring a reference surface.

  12. High resolution hybrid optical and acoustic sea floor maps (Invited)

    NASA Astrophysics Data System (ADS)

    Roman, C.; Inglis, G.

    2013-12-01

    This abstract presents a method for creating hybrid optical and acoustic sea floor reconstructions at centimeter scale grid resolutions with robotic vehicles. Multibeam sonar and stereo vision are two common sensing modalities with complementary strengths that are well suited for data fusion. We have recently developed an automated two stage pipeline to create such maps. The steps can be broken down as navigation refinement and map construction. During navigation refinement a graph-based optimization algorithm is used to align 3D point clouds created with both the multibeam sonar and stereo cameras. The process combats the typical growth in navigation error that has a detrimental affect on map fidelity and typically introduces artifacts at small grid sizes. During this process we are able to automatically register local point clouds created by each sensor to themselves and to each other where they overlap in a survey pattern. The process also estimates the sensor offsets, such as heading, pitch and roll, that describe how each sensor is mounted to the vehicle. The end results of the navigation step is a refined vehicle trajectory that ensures the points clouds from each sensor are consistently aligned, and the individual sensor offsets. In the mapping step, grid cells in the map are selectively populated by choosing data points from each sensor in an automated manner. The selection process is designed to pick points that preserve the best characteristics of each sensor and honor some specific map quality criteria to reduce outliers and ghosting. In general, the algorithm selects dense 3D stereo points in areas of high texture and point density. In areas where the stereo vision is poor, such as in a scene with low contrast or texture, multibeam sonar points are inserted in the map. This process is automated and results in a hybrid map populated with data from both sensors. Additional cross modality checks are made to reject outliers in a robust manner. The final

  13. High-resolution proxy record of Holocene climate from a loess section in Southwestern Nebraska, USA

    USGS Publications Warehouse

    Miao, X.; Mason, J.A.; Johnson, W.C.; Wang, Hongfang

    2007-01-01

    Multi-proxy analysis was used to produce a high-resolution paleoclimatic record from an exceptionally thick section of the Holocene Bignell Loess near Wauneta, Southwestern Nebraska, in the central Great Plains. The Wauneta section has excellent age control, based on optically stimulated luminescence (OSL) and radiocarbon dating, and records multiple episodes of rapid loess deposition alternating with slower deposition and soil formation. The lowermost and uppermost OSL ages obtained from the Bignell Loess are 10,250 ?? 610??years (5.9??m depth) and 100 ?? 10??years (0.1??m depth), respectively. As a result, the Holocene has been temporally confined. Stratigraphically, the Bignell Loess overlies the Late Pleistocene Peoria Loess (deposited ??? 21-14??ka), and the two units are separated by the Brady Soil which is distinguished by its color and other pedogenic features. L*a*b* color parameters and organic carbon content of Bignell Loess are sensitive proxies to differentiate drought-induced aeolian sediment layers from the intercalated soil horizons. Soil organic carbon-derived ??13C data suggest that the C3-dominated floral environment during Peoria Loess deposition shifted dramatically to a C4-dominated environment during Brady Soil formation in response to a warming trend. Even greater C4 abundance characterized the late Holocene. High-resolution ??13C data support the contention that C3 vs. C4 vegetation change in the Holocene reflects ecosystem response to frequent vegetation disturbance under arid conditions. Time series analysis reveals that ??13C and color parameters display high frequency variation with periodicities of 103-118??years and 103??years, respectively. Similar periodicities were also reported in studies of North Dakota lakes, though the physical mechanism responsible is uncertain. Comparison of Bignell Loess color and tropical Pacific sea surface temperatures (SSTs) allows evaluation of a proposed teleconnection between drought in the Great

  14. Acoustic force mapping in a hybrid acoustic-optical micromanipulation device supporting high resolution optical imaging.

    PubMed

    Thalhammer, Gregor; McDougall, Craig; MacDonald, Michael Peter; Ritsch-Marte, Monika

    2016-04-21

    Many applications in the life-sciences demand non-contact manipulation tools for forceful but nevertheless delicate handling of various types of sample. Moreover, the system should support high-resolution optical imaging. Here we present a hybrid acoustic/optical manipulation system which utilizes a transparent transducer, making it compatible with high-NA imaging in a microfluidic environment. The powerful acoustic trapping within a layered resonator, which is suitable for highly parallel particle handling, is complemented by the flexibility and selectivity of holographic optical tweezers, with the specimens being under high quality optical monitoring at all times. The dual acoustic/optical nature of the system lends itself to optically measure the exact acoustic force map, by means of direct force measurements on an optically trapped particle. For applications with (ultra-)high demand on the precision of the force measurements, the position of the objective used for the high-NA imaging may have significant influence on the acoustic force map in the probe chamber. We have characterized this influence experimentally and the findings were confirmed by model simulations. We show that it is possible to design the chamber and to choose the operating point in such a way as to avoid perturbations due to the objective lens. Moreover, we found that measuring the electrical impedance of the transducer provides an easy indicator for the acoustic resonances. PMID:27025398

  15. High-resolution handheld rigid endomicroscope based on full-field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Benoit a la Guillaume, Emilie; Martins, Franck; Boccara, Claude; Harms, Fabrice

    2016-02-01

    Full-field optical coherence tomography (FF-OCT) is a powerful tool for nondestructive assessment of biological tissue, i.e., for the structural examination of tissue in depth at a cellular resolution. Mostly known as a microscopy device for ex vivo analysis, FF-OCT has also been adapted to endoscopy setups since it shows good potential for in situ cancer diagnosis and biopsy guidance. Nevertheless, all the attempts to perform endoscopic FF-OCT imaging did not go beyond lab setups. We describe here, to the best of our knowledge, the first handheld FF-OCT endoscope based on a tandem interferometry assembly using incoherent illumination. A common-path passive imaging interferometer at the tip of an optical probe makes it robust and insensitive to environmental perturbations, and a low finesse Fabry-Perot processing interferometer guarantees a compact system. A good resolution (2.7 μm transverse and 6 μm axial) is maintained through the long distance, small diameter relay optics of the probe, and a good signal-to-noise ratio is achieved in a limited 100 ms acquisition time. High-resolution images and a movie of a rat brain slice have been recorded by moving the contact endoscope over the surface of the sample, allowing for tissue microscopic exploration at 20 μm under the surface. These promising ex vivo results open new perspectives for in vivo imaging of biological tissue, in particular, in the field of cancer and surgical margin assessment.

  16. An integral design strategy combining optical system and image processing to obtain high resolution images

    NASA Astrophysics Data System (ADS)

    Wang, Jiaoyang; Wang, Lin; Yang, Ying; Gong, Rui; Shao, Xiaopeng; Liang, Chao; Xu, Jun

    2016-05-01

    In this paper, an integral design that combines optical system with image processing is introduced to obtain high resolution images, and the performance is evaluated and demonstrated. Traditional imaging methods often separate the two technical procedures of optical system design and imaging processing, resulting in the failures in efficient cooperation between the optical and digital elements. Therefore, an innovative approach is presented to combine the merit function during optical design together with the constraint conditions of image processing algorithms. Specifically, an optical imaging system with low resolution is designed to collect the image signals which are indispensable for imaging processing, while the ultimate goal is to obtain high resolution images from the final system. In order to optimize the global performance, the optimization function of ZEMAX software is utilized and the number of optimization cycles is controlled. Then Wiener filter algorithm is adopted to process the image simulation and mean squared error (MSE) is taken as evaluation criterion. The results show that, although the optical figures of merit for the optical imaging systems is not the best, it can provide image signals that are more suitable for image processing. In conclusion. The integral design of optical system and image processing can search out the overall optimal solution which is missed by the traditional design methods. Especially, when designing some complex optical system, this integral design strategy has obvious advantages to simplify structure and reduce cost, as well as to gain high resolution images simultaneously, which has a promising perspective of industrial application.

  17. Observation of thermomagnetically recorded domains with high-resolution magnetic soft x-ray microscopy

    NASA Astrophysics Data System (ADS)

    Tsunashima, S.; Takagi, Nayuki; Yamaguchi, Atushi; Kume, Minoru; Fischer, P.; Kumazawa, M.

    2003-04-01

    Magnetic domains were thermomagnetically recorded on TbFeCo films using laser pulsed magnetic field modulation (LP-MFM) and light intensity modulation (LIM). The domains were observed with high resolution magnetic transmission X-ray microscopy (M-TXM) before and after the heat treatment in order to clarify the recording characteristics and the thermal stability of recorded domains. From the results of M-TXM images, it was found that isolated single marks whose lengths are much smaller than 100 nm can be recorded by LP-MFM but their mark lengths become often longer than designed. It was further confirmed that the heat treatment at 120 degree C for 50 hours does not influence significantly the crescent-shaped magnetic domains of 100 nm in width recorded using LP-MFM method and circular domains of 150 nm in diameter recorded using LIM method.

  18. Optic for an endoscope/borescope having high resolution and narrow field of view

    DOEpatents

    Stone, Gary F.; Trebes, James E.

    2003-10-28

    An optic having optimized high spatial resolution, minimal nonlinear magnification distortion while at the same time having a limited chromatic focal shift or chromatic aberrations. The optic located at the distal end of an endoscopic inspection tool permits a high resolution, narrow field of view image for medical diagnostic applications, compared to conventional optics for endoscopic instruments which provide a wide field of view, low resolution image. The image coverage is over a narrow (<20 degrees) field of view with very low optical distortion (<5% pin cushion or barrel distortion. The optic is also optimized for best color correction as well as to aid medical diagnostics.

  19. On-demand optical immobilization of Caenorhabditis elegans for high-resolution imaging and microinjection

    PubMed Central

    Hwang, Hyundoo; Krajniak, Jan; Matsunaga, Yohei; Benian, Guy M.

    2014-01-01

    This paper describes a novel selected immobilization technique based on optical control of the sol-gel transition of thermoreversible Pluronic gel, which provides a simple, versatile, and biocompatible approach for high-resolution imaging and microinjection of Caenorhabditis elegans. PMID:25056343

  20. On the optical stability of high-resolution transmission electron microscopes.

    PubMed

    Barthel, J; Thust, A

    2013-11-01

    In the recent two decades the technique of high-resolution transmission electron microscopy experienced an unprecedented progress through the introduction of hardware aberration correctors and by the improvement of the achievable resolution to the sub-Ångström level. The important aspect that aberration correction at a given resolution requires also a well defined amount of optical stability has received little attention so far. Therefore we investigate the qualification of a variety of high-resolution electron microscopes to maintain an aberration corrected optical state in terms of an optical lifetime. We develop a comprehensive statistical framework for the estimation of the optical lifetime and find remarkably low values between tens of seconds and a couple of minutes. Probability curves are introduced, which inform the operator about the chance to work still in the fully aberration corrected state.

  1. High-Resolution Adaptive Optics Test-Bed for Vision Science

    SciTech Connect

    Wilks, S C; Thomspon, C A; Olivier, S S; Bauman, B J; Barnes, T; Werner, J S

    2001-09-27

    We discuss the design and implementation of a low-cost, high-resolution adaptive optics test-bed for vision research. It is well known that high-order aberrations in the human eye reduce optical resolution and limit visual acuity. However, the effects of aberration-free eyesight on vision are only now beginning to be studied using adaptive optics to sense and correct the aberrations in the eye. We are developing a high-resolution adaptive optics system for this purpose using a Hamamatsu Parallel Aligned Nematic Liquid Crystal Spatial Light Modulator. Phase-wrapping is used to extend the effective stroke of the device, and the wavefront sensing and wavefront correction are done at different wavelengths. Issues associated with these techniques will be discussed.

  2. Optical fibers for high-resolution in vivo microendoscopic fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Oh, Gyungseok; Chung, Euiheon; Yun, Seok H.

    2013-12-01

    Optical fiber-based high-resolution fluorescence imaging techniques have promising applications in clinical practice and preclinical research using animals. Here we review the instrumentation and applications of microendoscopy based on various types of optical fibers. Single-mode fibers and double-clad fibers have been widely used for delivering light from light sources to tissues and collecting light from tissues to photodetectors. Coherent fiber bundles, cylindrical graded-index lenses, and multi-mode fibers have been employed in both beam-scanning and non-scanning microscopy. With continuing advances of optical fiber technologies, further innovations in optical microendoscopy are expected.

  3. High-resolution imaging of biological tissue with full-field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhu, Yue; Gao, Wanrong

    2015-03-01

    A new full-field optical coherence tomography system with high-resolution has been developed for imaging of cells and tissues. Compared with other FF-OCT (Full-field optical coherence tomography, FF-OCT) systems illuminated with optical fiber bundle, the improved Köhler illumination arrangement with a halogen lamp was used in the proposed FF-OCT system. High numerical aperture microscopic objectives were used for imaging and a piezoelectric ceramic transducer (PZT) was used for phase-shifting. En-face tomographic images can be obtained by applying the five-step phase-shifting algorithm to a series of interferometric images which are recorded by a smart camera. Three-dimensional images can be generated from these tomographic images. Imaging of the chip of Intel Pentium 4 processor demonstrated the ultrahigh resolution of the system (lateral resolution is 0.8μm ), which approaches the theoretical resolution 0.7 μm× 0.5 μm (lateral × axial). En-face images of cells of onion show an excellent performance of the system in generating en-face images of biological tissues. Then, unstained pig stomach was imaged as a tissue and gastric pits could be easily recognized using FF-OCT system. Our study provides evidence for the potential ability of FFOCT in identifying gastric pits from pig stomach tissue. Finally, label-free and unstained ex vivo human liver tissues from both normal and tumor were imaged with this FFOCT system. The results show that the setup has the potential for medical diagnosis applications such liver cancer diagnosis.

  4. [Measurement of OH radicals in flame with high resolution differential optical absorption spectroscopy].

    PubMed

    Liu, Yu; Liu, Wen-Qing; Kan, Rui-Feng; Si, Fu-Qi; Xu, Zhen-Yu; Hu, Ren-Zhi; Xie, Pin-Hua

    2011-10-01

    The present paper describes a new developed high resolution differential optical absorption spectroscopy instrument used for the measurement of OH radicals in flame. The instrument consists of a Xenon lamp for light source; a double pass high resolution echelle spectrometer with a resolution of 3.3 pm; a multiple-reflection cell of 20 meter base length, in which the light reflects in the cell for 176 times, so the whole path length of light can achieve 3 520 meters. The OH radicals'6 absorption lines around 308 nm were simultaneously observed in the experiment. By using high resolution DOAS technology, the OH radicals in candles, kerosene lamp, and alcohol burner flames were monitored, and their concentrations were also inverted. PMID:22250529

  5. Flexible high-resolution film recorder system. [in NASA image processing facility for remote sensor data

    NASA Technical Reports Server (NTRS)

    Heffner, P.; Connell, E.

    1980-01-01

    The paper describes a high-resolution film recorder (HRFR) system capable of meeting the requirements of all of the imaging sensors for the recording support of NASA missions. The technical requirements imposed by sensor constraints and end users of the film product are examined, along with the implementation techniques to satisfy these requirements. The recorder can produce annotated imagery with array sizes ranging from 1 to 400 million picture elements and a programmable radiometric transfer function provided by the recorder. The HRFR requirements were grouped into three categories: (1) front end (input) requirements defined by the input medium, (2) operational requirements based on the volume, throughput, and changeover time from one mode to another, and (3) film product requirements determined by the needs of the end product user.

  6. Fiber optic cable-based high-resolution, long-distance VGA extenders

    NASA Astrophysics Data System (ADS)

    Rhee, Jin-Geun; Lee, Iksoo; Kim, Heejoon; Kim, Sungjoon; Koh, Yeon-Wan; Kim, Hoik; Lim, Jiseok; Kim, Chur; Kim, Jungwon

    2013-02-01

    Remote transfer of high-resolution video information finds more applications in detached display applications for large facilities such as theaters, sports complex, airports, and security facilities. Active optical cables (AOCs) provide a promising approach for enhancing both the transmittable resolution and distance that standard copper-based cables cannot reach. In addition to the standard digital formats such as HDMI, the high-resolution, long-distance transfer of VGA format signals is important for applications where high-resolution analog video ports should be also supported, such as military/defense applications and high-resolution video camera links. In this presentation we present the development of a compressionless, high-resolution (up to WUXGA, 1920x1200), long-distance (up to 2 km) VGA extenders based on serialized technique. We employed asynchronous serial transmission and clock regeneration techniques, which enables lower cost implementation of VGA extenders by removing the necessity for clock transmission and large memory at the receiver. Two 3.125-Gbps transceivers are used in parallel to meet the required maximum video data rate of 6.25 Gbps. As the data are transmitted asynchronously, 24-bit pixel clock time stamp is employed to regenerate video pixel clock accurately at the receiver side. In parallel to the video information, stereo audio and RS-232 control signals are transmitted as well.

  7. High-Resolution Imaging of the Optic Nerve and Retina in Optic Nerve Hypoplasia

    PubMed Central

    Pilat, Anastasia; Sibley, Daniel; McLean, Rebecca J.; Proudlock, Frank A.; Gottlob, Irene

    2015-01-01

    Purpose To investigate the optic nerve and macular morphology in patients with optic nerve hypoplasia (ONH) using spectral-domain optical coherence tomography (SD OCT). Design Prospective, cross-sectional, observational study. Subjects A total of 16 participants with ONH (10 female and 6 male; mean age, 17.2 years; 6 bilateral involvement) and 32 gender-, age-, ethnicity-, and refraction-matched healthy controls. Methods High-resolution SD OCT (Copernicus [Optopol Technology S.A., Zawiercie, Poland], 3 μm resolution) and handheld SD OCT (Bioptigen Inc [Research Triangle Park, NC], 2.6 μm resolution) devices were used to acquire horizontal scans through the center of the optic disc and macula. Main Outcome Measures Horizontal optic disc/cup and rim diameters, cup depth, peripapillary retinal nerve fiber layer (RNFL), and thickness of individual retinal layers in participants with ONH and in controls. Results Patients with ONH had significantly smaller discs (P < 0.03 and P < 0.001 compared with unaffected eye and healthy controls, respectively), horizontal cup diameter (P < 0.02 for both), and cup depth (P < 0.02 and P < 0.01, respectively). In the macula, significantly thinner RNFL (nasally), ganglion cell layer (GCL) (nasally and temporally), inner plexiform layer (IPL) (nasally), outer nuclear layer (ONL) (nasally), and inner segment (centrally and temporally) were found in patients with ONH compared with the control group (P < 0.05 for all comparisons). Continuation of significantly thicker GCL, IPL, and outer plexiform layer in the central retinal area (i.e., foveal hypoplasia) was found in more than 80% of patients with ONH. Clinically unaffected fellow eyes of patients with ONH showed mild features of underdevelopment. Visual acuity and presence of septo-optic dysplasia were associated with changes in GCL and IPL. Sensitivity and specificity for the detection of ONH based on disc and retinal optical coherence tomography (OCT) parameters were >80

  8. Military reconnaissance application of high-resolution optical satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Wang, Zheng-gang; Kang, Qing; Xun, Yi-jia; Shen, Zhi-qiang; Cui, Chang-bin

    2014-11-01

    As the remote sensing technology transformation from military use to civil use becomes deeper and faster, the resolution is better and better, and the relative techniques of the civil optical remote sensing satellite are richer and richer. So, modes such as civil use replacing military use, civil use covering military use, and civil use supporting military use are the real portraiture of high-resolution optical satellite remote sensing development currently. Taking the situations of the Taiwan authorities buying commercial remote sensing image to military reconnaissance, and the so-called military establishments exposed by media using satellite image as an example, the military reconnaissance application of civil high-resolution optical satellite remote sensing is discussed. Then, the actuality and reasons of huge measure engineering and ruled configuring, environment and signs of military area, equipment and exercitation establishments and three-dimension information of engineering and equipment which can be detected easily by remote sensing are analyzed.

  9. High-resolution optical spectroscopy of RS Ophiuchi during 2008 - 2009

    NASA Astrophysics Data System (ADS)

    Somero, A.; Hakala, P.; Wynn, G. A.

    2016-10-01

    RS Ophiuchi is a symbiotic variable and a recurrent nova. We have monitored it with the Nordic Optical Telescope and obtained 30 high resolution (R=46 000) optical spectra over one orbital cycle during quiescence. To our knowledge this is the best-sampled high resolution spectroscopic dataset of RS Oph over one orbital period. We do not detect any direct signatures of an accretion disc such as double peaked emission lines, but many line profiles are complex consisting of superimposed emission and absorption components. We measure the spin of the red giant and conclude that it is tidally locked to the binary orbit. We observe Na I absorption features, probably arising from the circumbinary medium, that has been shaped by previous recurrent nova outbursts. We do not detect any intrinsic polarisation in the optical wavelengths.

  10. a Decade-Spanning High-Resolution Asynchronous Optical Sampling Based Terahertz Time-Domain Spectrometer

    NASA Astrophysics Data System (ADS)

    Good, Jacob T.; Holland, Daniel; Finneran, Ian A.; Carroll, Brandon; Allodi, Marco A.; Blake, Geoffrey

    2015-06-01

    High-resolution ASynchronous OPtical Sampling (ASOPS) is a technique that substantially improves the combined frequency resolution and bandwidth of ASOPS based TeraHertz Time-Domain Spectroscopy (THz-TDS) systems. We employ two mode-locked femtosecond Ti:Sapphire oscillators with repetition frequencies of 80 MHz operating at a fixed repetition frequency offset of 100 Hz. This offset lock is maintained by a Phase-Locked Loop (PLL) operating at the 60th harmonic of the repetition rate of the Ti:Sapphire oscillators. Their respective time delay is scanned across 12.5 ns requiring a scan time of 10 ms, supporting a time delay resolution of up to 15.6 fs. ASOPS-THz-TDS enables high-resolution spectroscopy that is impossible for a THz-TDS system employing a mechanical delay stage. We measure a timing jitter of 1.36 fs for the system using an air-gap etalon and an optical cross-correlator. We report a Root-Mean-Square deviation of 20.7 MHz and a mean deviation of 14.4 MHz for water absorption lines from 0.5 to 2.7. High-resolution ASOPS-THz-TDS enables high resolution spectroscopy of both gas-phase and condensed-phase samples across a decade of THz bandwidth.

  11. Optical design of a versatile FIRST high-resolution near-IR spectrograph

    NASA Astrophysics Data System (ADS)

    Zhao, Bo; Ge, Jian

    2012-09-01

    We report the update optical design of a versatile FIRST high resolution near IR spectrograph, which is called Florida IR Silicon immersion grating spectromeTer (FIRST). This spectrograph uses cross-dispersed echelle design with white pupils and also takes advantage of the image slicing to increase the spectra resolution, while maintaining the instrument throughput. It is an extremely high dispersion R1.4 (blazed angle of 54.74°) silicon immersion grating with a 49 mm diameter pupil is used as the main disperser at 1.4μm -1.8μm to produce R=72,000 while an R4 echelle with the same pupil diameter produces R=60,000 at 0.8μm -1.35μm. Two cryogenic Volume Phase Holographic (VPH) gratings are used as cross-dispersers to allow simultaneous wavelength coverage of 0.8μm -1.8μm. The butterfly mirrors and dichroic beamsplitters make a compact folding system to record these two wavelength bands with a 2kx2k H2RG array in a single exposure. By inserting a mirror before the grating disperser (the SIG and the echelle), this spectrograph becomes a very efficient integral field 3-D imaging spectrograph with R=2,000-4,000 at 0.8μm-1.8μm by coupling a 10x10 telescope fiber bundle with the spectrograph. Details about the optical design and performance are reported.

  12. Construction of a high resolution microscope with conventional and holographic optical trapping capabilities.

    PubMed

    Butterfield, Jacqualine; Hong, Weili; Mershon, Leslie; Vershinin, Michael

    2013-04-22

    High resolution microscope systems with optical traps allow for precise manipulation of various refractive objects, such as dielectric beads (1) or cellular organelles (2,3), as well as for high spatial and temporal resolution readout of their position relative to the center of the trap. The system described herein has one such "traditional" trap operating at 980 nm. It additionally provides a second optical trapping system that uses a commercially available holographic package to simultaneously create and manipulate complex trapping patterns in the field of view of the microscope (4,5) at a wavelength of 1,064 nm. The combination of the two systems allows for the manipulation of multiple refractive objects at the same time while simultaneously conducting high speed and high resolution measurements of motion and force production at nanometer and piconewton scale.

  13. Early Doppler Performance from New Generation High Resolution Optical and near Infrared Planet-hunting Spectrographs

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Varosi, F.; Powell, S.; Zhao, B.; Schofield, S.; Liu, J.; Warner, C.; Sithajan, S.; Li, R.; Muterspaugh, M. W.; Williamson, M. W.; Avner, L.; Jakeman, H.

    2014-01-01

    The next generation of radial velocity (RV) planet surveys require high precision (sub m/s for optical and 1-3 m/s for near infrared (NIR)) and high cadence 100 RV measurements per star) to systematically reach low mass planet populations, including habitable Earth-like planets, around FGKM dwarfs and study their properties. These require new sensitive optical and NIR high resolution spectrographs. At UF, we have developed two new generation optical and NIR high resolution spectrographs for high precision RV low mass planet surveys. The optical high resolution spectrograph called EXtremely high Precision ExtrasolaR planet Tracker (EXPERT) III (EXPERT-III), was commissioned at the Automatic Spectroscopic Telescope (AST), a robotic telescope at Fairborn Observatory in Arizona in July 2013 and has produced a spectral resolution of about 100,000 and a simultaneous wavelength coverage of 0.38-0.9 mm with a 4kx4k back-illuminated Fairchild CCD detector. The early RV measurements show that this instrument has reached ~0.7 m/s RV precision and daily instrument stability is better than 5m/s. The near IR spectrograph, called the Florida IR Silicon immersion grating spectromeTer (FIRST), has produced 60,000 at 0.8-1.8 microns with a 2kx2k H2RG IR array. FIRST is the first high resolution NIR spectrograph taking full advantage of an innovative silicon immersion grating to achieve high spectral resolution (3.4 times higher than a commercially available echelle grating of the equal size and blaze angle) in an extremely compact design. FIRST is schedule to be commissioned at AST in October 2013. Here we report on-sky RV performance and early science results from the AST robotic observations.

  14. InSAR Forensics: Tracing InSAR Scatterers in High Resolution Optical Image

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhu, XiaoXiang

    2015-05-01

    This paper presents a step towards a better interpretation of the scattering mechanism of different objects and their deformation histories in SAR interferometry (InSAR). The proposed technique traces individual SAR scatterer in high resolution optical images where their geometries, materials, and other properties can be better analyzed and classified. And hence scatterers of a same object can be analyzed in group, which brings us to a new level of InSAR deformation monitoring.

  15. Optimal site selection for a high-resolution ice core record in East Antarctica

    NASA Astrophysics Data System (ADS)

    Vance, Tessa R.; Roberts, Jason L.; Moy, Andrew D.; Curran, Mark A. J.; Tozer, Carly R.; Gallant, Ailie J. E.; Abram, Nerilie J.; van Ommen, Tas D.; Young, Duncan A.; Grima, Cyril; Blankenship, Don D.; Siegert, Martin J.

    2016-03-01

    Ice cores provide some of the best-dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high-resolution ice core record. Specifically, seven criteria are considered: (1) 2000-year-old ice at 300 m depth; (2) above 1000 m elevation; (3) a minimum accumulation rate of 250 mm years-1 IE (ice equivalent); (4) minimal surface reworking to preserve the deposited climate signal; (5) a site with minimal displacement or elevation change in ice at 300 m depth; (6) a strong teleconnection to midlatitude climate; and (7) an appropriately complementary relationship to the existing Law Dome record (a high-resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change, and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure that a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50-100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable, and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.

  16. Optimal site selection for a high resolution ice core record in East Antarctica

    NASA Astrophysics Data System (ADS)

    Vance, T.; Roberts, J.; Moy, A.; Curran, M.; Tozer, C.; Gallant, A.; Abram, N.; van Ommen, T.; Young, D.; Grima, C.; Blankenship, D.; Siegert, M.

    2015-11-01

    Ice cores provide some of the best dated and most comprehensive proxy records, as they yield a vast and growing array of proxy indicators. Selecting a site for ice core drilling is nonetheless challenging, as the assessment of potential new sites needs to consider a variety of factors. Here, we demonstrate a systematic approach to site selection for a new East Antarctic high resolution ice core record. Specifically, seven criteria are considered: (1) 2000 year old ice at 300 m depth, (2) above 1000 m elevation, (3) a minimum accumulation rate of 250 mm yr-1 IE, (4) minimal surface re-working to preserve the deposited climate signal, (5) a site with minimal displacement or elevation change of ice at 300 m depth, (6) a strong teleconnection to mid-latitude climate and (7) an appropriately complementary relationship to the existing Law Dome record (a high resolution record in East Antarctica). Once assessment of these physical characteristics identified promising regions, logistical considerations (for site access and ice core retrieval) were briefly considered. We use Antarctic surface mass balance syntheses, along with ground-truthing of satellite data by airborne radar surveys to produce all-of-Antarctica maps of surface roughness, age at specified depth, elevation and displacement change and surface air temperature correlations to pinpoint promising locations. We also use the European Centre for Medium-Range Weather Forecast ERA 20th Century reanalysis (ERA-20C) to ensure a site complementary to the Law Dome record is selected. We find three promising sites in the Indian Ocean sector of East Antarctica in the coastal zone from Enderby Land to the Ingrid Christensen Coast (50-100° E). Although we focus on East Antarctica for a new ice core site, the methodology is more generally applicable and we include key parameters for all of Antarctica which may be useful for ice core site selection elsewhere and/or for other purposes.

  17. A High-resolution Detrital and Oxygen Isotope Record from Flemish Pass, Labrador Sea

    NASA Astrophysics Data System (ADS)

    deJesus, E.; Hoffman, J. S.; Clark, P. U.; Mix, A. C.

    2014-12-01

    High-resolution records of deglacial paleoceanographic change along the Labrador shelf are scarce. However, they are required in order to characterize and understand possible ice-ocean interactions involving the eastern sector of the Laurentide Ice Sheet (LIS). We have generated a high-resolution stable isotope and detrital stratigraphic record for core HU2001043-008 (990m, 48° N, 45° W) from Flemish Pass, Labrador Sea, to better understand the role of LIS ice-rafting events in abrupt climate changes during the last glaciation. Samples at two-centimeter resolution were disaggregated, washed, and picked for Neogloboquandrina pachyderma (sinistral) for stable isotope and radiocarbon analysis. The δ18O signal in foraminiferal calcite allows us to examine surface-ocean changes that may indicate an influx of freshwater, which may or may not be related to an LIS ice-rafting event. Our results will help in developing a better understanding of the source of LIS ice-rafting events, precursory indicators of the events, and how these events are associated with changes in deep-water formation in the Labrador Sea.

  18. Information content capabilities of very high resolution optical space imagery for updating GIS database

    NASA Astrophysics Data System (ADS)

    Alkan, Mehmet; Jacobsen, Karsten

    2015-05-01

    Nowadays, the number and capacity of very high resolution optical satellites grows permanently, so the access to very high resolution space images is not any more a problem. The use of Geographic Information Systems (GISs) together with Remote Sensing became important. With the increased ground resolution a competition to aerial images exist. For the generation of topographic maps, today available as GIS, the accuracy and the information content - what elements can be identified in the image - are important. Both may limit the presentation scale of topographic maps. As horizontal accuracy 0.25mm up to 0.3mm in the map scale are accepted. The required information content is more complicate. The object details to be presented in topographic maps vary from area to area which is based on the planned and unplanned areas. In this study, images from IRS-1C, Kompsat-1, SPOT 5, OrbView-3, IKONOS, QuickBird and WorldView-1 have been used for topographic mapping. For this reason, Zonguldak test fields are an important area for applications of the high resolution imageries. The details which can be identified in the space images dominantly depends upon the ground resolution, available as ground sampling distance (GSD). In this study, high resolution imageries have been tested depending on the GSD and corresponding to the map scales for updating GIS database.

  19. A new high-resolution record of Holocene geomagnetic secular variation from New Zealand

    NASA Astrophysics Data System (ADS)

    Turner, G. M.; Howarth, J. D.; de Gelder, G. I. N. O.; Fitzsimons, S. J.

    2015-11-01

    We present the first full Holocene palaeomagnetic secular variation record from New Zealand. The 11 500 year-long record, from the sediments of Mavora Lakes, comprises composite declination, inclination and relative palaeointensity logs, compiled from two six-metre long cores and the uppermost 1.5 m of another. An age model has been developed from 28 AMS radiocarbon age determinations on fragments of southern beech (Lophozonia menziesii and Fuscospora cliffortioides) leaves. The excellent between-core correlation in all three components of the field results in a high-resolution palaeosecular variation record, with precise and accurate age control. The variations change in character from high amplitude in-phase declination and inclination swings in the earliest part of the record to low amplitude variations in the middle part and declination and inclination swings that are 90° out of phase, leading to broad looping of the vector in the upper part of the record, that is consistent with westward drifting sources in the outer core. The present-day field at the site (Dec = 24.2°E, Inc = - 70.7 °, F = 59 μT) represents a rare steep and easterly extreme direction, but close to average intensity. The palaeointensity is inferred to have varied between about 40 and 90 μT, with variations that, to some extent, mirror variations in the virtual axial geomagnetic dipole moment seen from global data, but also show some notable differences, particularly in the past few thousand years.

  20. Feasibility of endovascular optical coherence tomography for high-resolution carotid vessel wall imaging

    NASA Astrophysics Data System (ADS)

    Cheng, Kyle H. Y.; Sun, Cuiru; Cruz, Juan P.; Marotta, Thomas R.; Spears, Julian; Montanera, Walter J.; Herman, Peter R.; Thind, Aman; Courtney, Brian; Standish, Beau A.; Yang, Victor X. D.

    2012-02-01

    Carotid Artery Stenting (CAS) is a procedure that treats carotid atherosclerosis which should be monitored by in vivo high resolution imaging for the quality of the procedure and potential complications. The purpose of this pilot study is to evaluate the ability of optical coherence tomography to construct high resolution two and three dimensional images of stenting in porcine carotid artery for high accuracy diagnostic purposes. Four Yorkshire pigs were anaesthetized and catheterized. A state-of-the-art optical coherence tomography (OCT) system (Lightlab Imaging, St. Jude Medical Inc.) and an automated injector were used to obtain both healthy and stented porcine carotid artery images. Data obtained were then processed for visualization. The state-of-the-art OCT system was able to capture high resolution images of both healthy and stented carotid arteries. High quality three dimensional images of stented carotid arteries were constructed, clearly depicting stent apposition and thrombus formation over different stents. The results demonstrated that current state-of-the-art OCT system can be used to generate high quality three dimensional images of carotid arterial stents for accurate diagnosis of stent apposition and complications under appropriate imaging conditions.

  1. In Situ Visualization of Tears on Contact Lens Using Ultra High Resolution Optical Coherence Tomography

    PubMed Central

    Wang, Jianhua; Jiao, Shuliang; Ruggeri, Marco; Shousha, Mohammed Abou; Chen, Qi

    2012-01-01

    Objective To demonstrate the capability of directly visualizing the tear film on contact lenses using optical coherence tomography (OCT). Methods Six eyes of three healthy subjects wearing PureVision and ACUVUE Advance soft and Boston RGP hard contact lenses were imaged with a custom built, high speed, ultra-high resolution spectral domain optical coherence tomograph. Refresh Liquigel was used to demonstrate the effect of artificial tears on the tear film. Results Ultra high resolution images of the pre- and post-lens films were directly visualized when each lens was inserted onto the eye. After the instillation of artificial tears during lens wear, the tear film was thicker. The post-lens tear film underneath the lens edge was clearly shown. Interactions between the lens edges and the ocular surface were obtained for each of the lens types and base curves. With a contrast enhancement agent, tear menisci on the contact lenses around the upper and lower eyelids were highlighted. With hard contact lenses, the tear film was visualized clearly and changed after a blink when the lens was pulled up by the lid. Conclusions Ultra-high resolution OCT is a potentially promising technique for imaging tears around contact lenses. This successful demonstration of in situ post-lens tear film imaging suggests that OCT could open a new era in studying tear dynamics during contact lens wear. The novel method may lead to new ways of evaluating contact lens fitting. PMID:19265323

  2. The Potential for High-Resolution Palaeoclimate Records of the Pliocene from Speleothems

    NASA Astrophysics Data System (ADS)

    Drysdale, R.; Woodhead, J. D.; Hellstrom, J. C.

    2014-12-01

    The Pliocene is widely regarded as a useful analogue for future greenhouse warming and is thus an important interval for palaeoclimate study. Much of what we know about climate through the Pliocene comes from marine sediments. However, we know relatively little about interannual to interdecadal variability, yet reconstructing Pliocene climate at such resolution has the potential to yield important information for testing climate models. Recent advances in uranium-lead (U-Pb) dating have paved the way for investigating Pliocene (and older) high-resolution palaeoclimate records from speleothems. We present such an example from the Nullarbor Plain, Australia. The Nullabor is an emerged, karstified platform of Eocene to Miocene limestones situated on the arid southern fringe of the Australian continent. Caves developed in the karst preserve a large archive of ancient calcite speleothems, in stark contrast to the virtual lack of calcite speleothems today. U-Pb radiometric dating of these speleothems reveals that most the growth occurred during the Pliocene. The geochemistry of these speleothems suggests that the Nullarbor was a wetter and more-vegetated environment at the time. High-resolution geochemical analyses and fluorescence microscopy show that some of the speleothems are almost certainly annually laminated, and contain multi-proxy signatures similar to Holocene speleothems that are commonly associated with hydrological processes. We present a series of encouraging preliminary results from several specimens.

  3. High Resolution Optical Imaging with the Low Cost Topsat Small Satellite

    NASA Astrophysics Data System (ADS)

    Laycock, J.; van der Zel, V.; Morris, N.; Park, G.; Levett, W.

    2004-11-01

    TopSat is designed to demonstrate the capabilities of low cost small satellites, for high resolution and image quality optical sensing missions. Launch is currently planned for Spring 2005. The satellite is capable of high resolution despite its small size, as a result of a novel camera design and an agile and accurate spacecraft attitude control system. The TopSat mission is a collaboration between four UK partners. QinetiQ leads the mission and is providing data handling and ground segment elements. Rutherford Appleton Laboratory (RAL) has developed the camera, Surrey Satellite Technology Limited (SSTL) is providing the platform, and Infoterra Ltd is responsible for developing commercial data markets. The programme is jointly funded by the UK Ministry of Defence (MoD) and by the British National Space Centre (BNSC).

  4. Far-field high resolution effects and manipulating of electromagnetic waves based on transformation optics

    NASA Astrophysics Data System (ADS)

    Ji, XueBin; Zang, XiaoFei; Li, Zhou; Shi, Cheng; Chen, Lin; Cai, Bin; Zhu, YiMing

    2015-05-01

    Based on the transformation optics (TO) and the effective medium theory (EMT), a new illusion media with homogeneous and isotropic materials is proposed to realize the far-field high resolution effects. When two point sources with the separation distance of λ0 / 4 are covered with the illusion media (λ0 is the free-space wavelength), the corresponding far-field pattern is equivalent to the case of two point sources with the separation distance larger than λ0 / 2 in free space, leading to the far-field high resolution effects (in free space, the separation distance of λ0 / 4 is less than half-wavelength, and thus the two point sources cannot be distinguished from each other). Furthermore, such illusion media can be applied to design tunable high-directivity antenna and an angle-dependent floating carpet cloak. Full wave simulations are carried out to verify the performance of our device.

  5. High-resolution and wide-bandwidth light intensity fiber optic displacement sensor for MEMS metrology.

    PubMed

    Orłowska, Karolina; Świątkowski, Michał; Kunicki, Piotr; Kopiec, Daniel; Gotszalk, Teodor

    2016-08-01

    We report on the design, properties, and applications of a high-resolution and wide-bandwidth light intensity fiber optic displacement sensor for microelectromechanical system (MEMS) metrology. There are two types of structures that the system is dedicated to: vibrating with both high and low frequencies. In order to ensure high-frequency and high-resolution measurements, frequency down mixing and selective signal processing were applied. The obtained effective measuring bandwidth ranges from single hertz to 1 megahertz. The achieved resolution presented here is 116  pm/Hz1/2 and 138  pm/Hz1/2 for low-frequency and high-frequency operation modes, respectively, whereas the measurement of static displacement is 100 μm.

  6. High-resolution and wide-bandwidth light intensity fiber optic displacement sensor for MEMS metrology.

    PubMed

    Orłowska, Karolina; Świątkowski, Michał; Kunicki, Piotr; Kopiec, Daniel; Gotszalk, Teodor

    2016-08-01

    We report on the design, properties, and applications of a high-resolution and wide-bandwidth light intensity fiber optic displacement sensor for microelectromechanical system (MEMS) metrology. There are two types of structures that the system is dedicated to: vibrating with both high and low frequencies. In order to ensure high-frequency and high-resolution measurements, frequency down mixing and selective signal processing were applied. The obtained effective measuring bandwidth ranges from single hertz to 1 megahertz. The achieved resolution presented here is 116  pm/Hz1/2 and 138  pm/Hz1/2 for low-frequency and high-frequency operation modes, respectively, whereas the measurement of static displacement is 100 μm. PMID:27505377

  7. High-resolution records of non-dipole variations derived from volcanic edifices

    NASA Astrophysics Data System (ADS)

    de Groot, Lennart; Biggin, Andrew; Dekkers, Mark

    2014-05-01

    Our understanding of the short-term behavior of the Earth's magnetic field is currently mainly hampered by a lack of coeval high-resolution records of geomagnetic intensity variations that are well distributed over the globe. Lavas are the only recorder of short-term fluctuations of the geomagnetic field that are available for all parts of the world and on geological time scales. Therefore, many efforts have been made to improve the methodology to obtain reliable estimates of the paleointensity from igneous rocks over the past decades. It is well known that some paleointensity methods will work on certain lavas with specific thermomagnetic behaviour, but fail for others. We therefore propose a 'multi-method paleointensity approach' that consists of Thellier-style, multispecimen-style, and calibrated pseudo-Thellier-style experiments to construct high-resolution records of regional variations in the intensity of the Earth's magnetic field. With our new approach we obtain a reliable estimate of the paleointensity for 60-70 percent of all cooling units sampled. By applying our new approach to suites of lavas from Hawaii (USA), and the Canary Islands (Spain) we obtain important constraints for short-term local geomagnetic intensity highs, and insight into their possible driving mechanisms. Our new record for Hawai'i indicates that, approximately 1000 years ago, the local field intensity increased on the order of 50% for 200 years - a qualitatively similar phenomenon observed 200 years earlier in western Europe (Gallet et al., 2005; Gomez-Paccard et al., 2012) and 500 years later in southwestern USA (Bowles et al., 2002). When these records are combined with a record for Japan (Yu, 2012), a coherent picture emerges that includes the dipole component decaying steadily since at least 1000 years ago. Superimposed onto this decay are strong but shorter-term intensity variations at a regional level whose asynchronicity necessitates a highly non-dipolar nature. Our

  8. High-resolution records of non-dipole variations derived from volcanic edifices

    NASA Astrophysics Data System (ADS)

    de Groot, L. V.; Biggin, A. J.; Dekkers, M. J.

    2013-12-01

    Our understanding of the short-term behavior of the Earth's magnetic field is currently mainly hampered by a lack of coeval high-resolution records of geomagnetic intensity variations that are well distributed over the globe. Lavas are the only recorder of short-term fluctuations of the geomagnetic field that are available for all parts of the world and on geological time scales. Therefore, many efforts have been made to improve the methodology to obtain reliable estimates of the paleointensity from igneous rocks over the past decades. It is well known that some paleointensity methods will work on certain lavas with specific thermomagnetic behavior, but fail for others. We therefore propose a ';multi-method paleointensity approach' that consists of Thellier-style, multispecimen-style, and calibrated pseudo-Thellier-style (AGU fall 2012 contribution GP43A-1122, submitted) experiments to construct high-resolution records of regional variations in the intensity of the Earth's magnetic field. With our new approach we obtain a reliable estimate of the paleointensity for 60-70 percent of all cooling units sampled. By applying our new approach to suites of lavas from Hawai'i (USA), and the Canary Islands (Spain) we obtain important constraints for short-term local geomagnetic intensity highs, and insight into their possible driving mechanisms. Our new record for Hawai'i indicates that, approximately 1000 years ago, the local field intensity increased on the order of 50% for 200 years - a qualitatively similar phenomenon observed 200 years earlier in western Europe (Gallet et al., 2005; Gómez-Paccard et al., 2012) and 500 years later in southwestern USA (Bowles et al., 2002). When these records are combined with a record for Japan (Yu, 2012), a coherent picture emerges that includes the dipole component decaying steadily since at least 1000 years ago. Superimposed onto this decay are strong but shorter-term intensity variations at a regional level whose asynchronicity

  9. High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century.

    PubMed

    Lima, Ana Lúcia C; Eglinton, Timothy I; Reddy, Christopher M

    2003-01-01

    A high-resolution record of polycyclic aromatic hydrocarbon (PAH) deposition in Rhode Island over the past approximately 180 years was constructed using a sediment core from the anoxic Pettaquamscutt River basin. The record showed significantly more structure than has hitherto been reported and revealed four distinct maxima in PAH flux. The characteristic increase in PAH flux at the turn of the 20th century was captured in detail, leading to an initial maximum prior to the Great Depression. The overall peak in PAH flux in the 1950s was followed by a maximum that immediately preceded the 1973 Organization of Petroleum Exporting Countries (OPEC) oil embargo. During the most recent portion of the record, an abrupt increase in PAH flux between 1996 and 1999 has been found to follow a period of near constant fluxes. Because source-diagnostic ratios indicate that petrogenic inputs are minor throughout the record, these trends are interpreted in terms of past variations in the magnitude and type of combustion processes. For the most recent PAH maximum, energy consumption data suggest that diesel fuel combustion, and hence traffic of heavier vehicles, is the most probable cause for the increase in PAH flux. Systematic variations in the relative abundance of individual PAHs in conjunction with the above changes in flux are interpreted in relation to the evolution of combustion processes. Coronene, retene, and perylene are notable exceptions, exhibiting unique down-core profiles. PMID:12542290

  10. High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from ODP Sites 1061 and 1062

    NASA Astrophysics Data System (ADS)

    Bourne, M. D.; Henderson, G. M.; Thomas, A. L.; Mac Niocaill, C.

    2012-12-01

    The Laschamp geomagnetic excursion (~41 ka) was a brief global deviation in geomagnetic field behaviour from that expected during normal secular variation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) and compare this record with previously published records of the Blake and Iceland Basin Excursions. Relatively high sedimentation rates (>10 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of 230Thxs concentration in the sediment to assess variations in the sedimentation rates through the core sections of interest. This allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. The Laschamp excursion at this location appears to be much shorter in duration than the Blake and Iceland Basin excursions. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 500 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical flux patches. Similar behaviour has been observed in records of the Iceland Basin Excursion from the same region. The palaeointensity record is in good agreement between the two sites. The palaeointensity record shows two minima, where the second dip in intensity is associated with a more limited directional deviation. Similar

  11. Low Frequency Error Analysis and Calibration for High-Resolution Optical Satellite's Uncontrolled Geometric Positioning

    NASA Astrophysics Data System (ADS)

    Wang, Mi; Fang, Chengcheng; Yang, Bo; Cheng, Yufeng

    2016-06-01

    The low frequency error is a key factor which has affected uncontrolled geometry processing accuracy of the high-resolution optical image. To guarantee the geometric quality of imagery, this paper presents an on-orbit calibration method for the low frequency error based on geometric calibration field. Firstly, we introduce the overall flow of low frequency error on-orbit analysis and calibration, which includes optical axis angle variation detection of star sensor, relative calibration among star sensors, multi-star sensor information fusion, low frequency error model construction and verification. Secondly, we use optical axis angle change detection method to analyze the law of low frequency error variation. Thirdly, we respectively use the method of relative calibration and information fusion among star sensors to realize the datum unity and high precision attitude output. Finally, we realize the low frequency error model construction and optimal estimation of model parameters based on DEM/DOM of geometric calibration field. To evaluate the performance of the proposed calibration method, a certain type satellite's real data is used. Test results demonstrate that the calibration model in this paper can well describe the law of the low frequency error variation. The uncontrolled geometric positioning accuracy of the high-resolution optical image in the WGS-84 Coordinate Systems is obviously improved after the step-wise calibration.

  12. Active compensation of flexure on the High-Resolution Optical Spectrograph for Gemini

    NASA Astrophysics Data System (ADS)

    D'Arrigo, P.; Diego, Francisco; Walker, David D.

    1997-03-01

    Gravity-induced flexure has been a long-standing challenge in Cassegrain spectrographs at 4-meter class telescopes; it is the more so at the scale of 8-meter telescopes. This is of particular concern for the Gemini high resolution optical spectrograph, which will be Cassegrain-mounted for its routine mode of operation. In this paper we address the general flexure problem, and how to solve it with the use of active optics. We also present the results of an experimental active flexure compensation system for the ISIS (intermediate- dispersion spectroscopic and imaging system) spectrograph on the 4.2 m William Herschel Telescope (WHT). This instrument, called ISAAC (ISIS spectrograph automatic active collimator), is based on the concept of active correction, where spectrum drifts, due to the spectrograph flexing under the effect of gravity, are compensated by the movement of an active optical element (in this case a fine steering tip-tilt collimator mirror). The experiment showed that active compensation can reduce flexure down to less than 3 micrometer over four hours of telescope motions, dramatically improving the spectrograph performance. The results of the experiment are used to discuss a flexure compensation system for the high resolution optical spectrograph (HROS) for the 8 m Gemini telescope.

  13. Ultra-high resolution spectral domain optical coherence tomography using supercontinuum light source

    NASA Astrophysics Data System (ADS)

    Lim, Yiheng; Yatagai, Toyohiko; Otani, Yukitoshi

    2016-04-01

    An ultra-high resolution spectral domain optical coherence tomography (SD-OCT) was developed using a cost-effective supercontinuum laser. A spectral filter consists of a dispersive prism, a cylindrical lens and a right-angle prism was built to transmit the wavelengths in range 680-940 nm to the OCT system. The SD-OCT has achieved 1.9 μm axial resolution and the sensitivity was estimated to be 91.5 dB. A zero-crossing fringes matching method which maps the wavelengths to the pixel indices of the spectrometer was proposed for the OCT spectral calibration. A double sided foam tape as a static sample and the tip of a middle finger as a biological sample were measured by the OCT. The adhesive and the internal structure of the foam of the tape were successfully visualized in three dimensions. Sweat ducts was clearly observed in the OCT images at very high resolution. To the best of our knowledge, this is the first demonstration of ultra-high resolution visualization of sweat duct by OCT.

  14. Contrast enhanced high-resolution diffuse optical tomography of the human brain using ICG

    PubMed Central

    Habermehl, Christina; Schmitz, Christoph H.; Steinbrink, Jens

    2011-01-01

    Non-invasive diffuse optical tomography (DOT) of the adult brain has recently been shown to improve the spatial resolution for functional brain imaging applications. Here we show that high-resolution (HR) DOT is also advantageous for clinical perfusion imaging using an optical contrast agent. We present the first HR-DOT results with a continuous wave near infrared spectroscopy setup using a dense grid of optical fibers and indocyanine green (ICG) as an exogenic contrast agent. We find an early arrival of the ICG bolus in the intracerebral tissue and a delayed arrival of the bolus in the extracerebral tissue, achieving the separation of both layers. This demonstrates the method’s potential for brain perfusion monitoring in neurointensive care patients. PMID:21935232

  15. Ultra-high resolution filter and optical field modulator based on a surface plasmon polariton.

    PubMed

    Wu, Wenjun; Yang, Junbo; Zhang, Jingjing; Huang, Jie; Chen, Dingbo; Wang, Hongqing

    2016-05-15

    A new filter structure and optical field modulator with ultra-high resolution based on plasmonic nano-cavity resonators is proposed and numerically investigated. The structure consists of a square nano-cavity resonator connected with several waveguides. All waveguides and cavity are etched on a silver film whose size is 1.1×0.75  μm. Compared with traditional filters, the FWHM (full width at half-maximum) of this structure's spectrum curve can be less than 7 nm; namely, the resolution has been greatly improved. The structure also presents the feature of an optical field modulator when both inputs are working simultaneously, and it provides a promising way to design and manufacture future optical logical device. PMID:27176990

  16. Fusing electro-optic and infrared signals for high resolution night images

    NASA Astrophysics Data System (ADS)

    Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

    2012-03-01

    Electro-optic (EO) images exhibit the properties of high resolution and low noise level, while it is a challenge to distinguish objects at night through infrared (IR) images, especially for objects with a similar temperature. Therefore, we will propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which will result in high resolution IR images and help us distinguish objects at night. Superimposing the detected edge of the EO image onto the corresponding transformed IR image is our principal idea for the proposed framework. In this framework, we will adopt the theoretical point spread function (PSF) proposed by Russell C. Hardie et al. for our IR image system, which is contributed by the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we will design an inverse filter in terms of the proposed PSF to conduct the IR image transformation. The framework requires four main steps, which are inverse filter-based IR image transformation, EO image edge detection, registration and superimposing of the obtained image pair. Simulation results will show the superimposed IR images.

  17. Optical fiber taper coupling and high-resolution wavelength tuning of microdisk resonators at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Srinivasan, Kartik; Painter, Oskar

    2007-01-01

    A system for studying microcavity resonators at cryogenic temperatures (˜10K) through evanescent coupling via optical fiber taper waveguides is reported, and efficient fiber coupling to AlGaAs microdisk cavities with embedded quantum dots is demonstrated. As an immediate application of this tool, the authors study high-resolution tuning of microdisk cavities through nitrogen gas adsorption, as first discussed by Mosor et al. [Appl. Phys. Lett. 87, 141105 (2005)]. By proper regulation of the nitrogen gas flow and delivery of the gas to the sample surface, continuous tuning can be achieved with modest gas flows, and overall wavelength shifts as large as 4nm are achieved.

  18. Developmental and morphological studies in Japanese medaka with ultra-high resolution optical coherence tomography

    PubMed Central

    Gladys, Fanny Moses; Matsuda, Masaru; Lim, Yiheng; Jackin, Boaz Jessie; Imai, Takuto; Otani, Yukitoshi; Yatagai, Toyohiko; Cense, Barry

    2015-01-01

    We propose ultra-high resolution optical coherence tomography to study the morphological development of internal organs in medaka fish in the post-embryonic stages at micrometer resolution. Different stages of Japanese medaka were imaged after hatching in vivo with an axial resolution of 2.8 µm in tissue. Various morphological structures and organs identified in the OCT images were then compared with the histology. Due to the medaka’s close resemblance to vertebrates, including humans, these morphological features play an important role in morphogenesis and can be used to study diseases that also occur in humans. PMID:25780725

  19. High-resolution coregistered intravascular imaging with integrated ultrasound and optical coherence tomography probe

    NASA Astrophysics Data System (ADS)

    Li, Xiang; Yin, Jiechen; Hu, Changhong; Zhou, Qifa; Shung, K. Kirk; Chen, Zhongping

    2010-09-01

    We report an integrated ultrasound (US) and optical coherence tomography (OCT) probe and system for intravascular imaging. The dual-function probe is based on a 50 MHz focused ring US transducer, with a centric hole for mounting OCT probe. The coaxial US and light beams are steered by a 45° mirror to enable coregistered US/OCT imaging simultaneously. Lateral resolution of US is improved due to focused ultrasonic beam. Mirror effects on US were investigated and in vitro imaging of a rabbit aorta has been carried out. The combined US-OCT system demonstrated high resolution in visualizing superficial arterial structures while retaining deep penetration of ultrasonic imaging.

  20. Performance of a high-resolution mid-IR optical-parametric-oscillator transient absorption spectrometer.

    PubMed

    Echebiri, Geraldine O; Smarte, Matthew D; Walters, Wendell W; Mullin, Amy S

    2014-06-16

    We report on a mid-IR optical parametric oscillator (OPO)-based high resolution transient absorption spectrometer for state-resolved collisional energy transfer. Transient Doppler-broadened line profiles at λ = 3.3 μm are reported for HCl R7 transitions following gas-phase collisions with vibrationally excited pyrazine. The instrument noise, analyzed as a function of IR wavelength across the absorption line, is as much as 10 times smaller than in diode laser-based measurements. The reduced noise is attributed to larger intensity IR light that has greater intensity stability, which in turn leads to reduced detector noise and better frequency locking for the OPO.

  1. High Resolution Spectroscopy of Naphthalene Calibrated by AN Optical Frequency Comb

    NASA Astrophysics Data System (ADS)

    Nishiyama, Akiko; Nakashima, Kazuki; Matsuba, Ayumi; Misono, Masatoshi

    2015-06-01

    In high-resolution molecular spectroscopy, the precise measure of the optical frequency is crucial to evaluate minute shifts and splittings of the energy levels. On the other hand, in such spectroscopy, thousands of spectral lines distributed over several wavenumbers have to be measured by a continuously scanning cw laser. Therefore, the continuously changing optical frequency of the scanning laser has to be determined with enough precision. To satisfy these contradictory requirements, we have been developed two types of high-resolution spectroscopic systems employing an optical frequency comb. One of the systems employs RF band-pass filters to generate equally spaced frequency markers for optical frequency calibration, and is appropriate for wide wavelength-range measurement with relatively high scanning rate.^a In the other system, the beat frequency between the optical frequency comb and the scanning laser is controlled by an acousto-optic frequency shifter. This system is suitable for more precise measurement, and enables detailed analyses of frequency characteristics of scanning laser.^b In the present study, we observe Doppler-free two-photon absorption spectra of A^1B1u (v_4 = 1) ← X^1A_g (v = 0) transition of naphthalene around 298 nm. The spectral lines are rotationally resolved and the resolution is about 100 kHz. For ^qQ transition, the rotational lines are assigned, and molecular constants in the excited state are determined. In addition, we analyze the origin of the measured linewidth and Coriolis interactions between energy levels. To determine molecular constants more precisely, we proceed to measure and analyze spectra of other transitions, such as ^sS transitions. ^a A. Nishiyama, D. Ishikawa, and M. Misono, J. Opt. Soc. Am. B 30, 2107 (2013). ^b A. Nishiyama, A. Matsuba, and M. Misono, Opt. Lett. 39, 4923 (2014).

  2. A High-Resolution Holocene Speleothem Record From Southwestern Oregon, USA

    NASA Astrophysics Data System (ADS)

    Ersek, V.; Clark, P. U.; Mix, A. C.; Cheng, H.; Edwards, L. R.

    2006-12-01

    Understanding the long-term predictability of climate change in the western U.S. is important because it impacts key resources such as agriculture, fish stocks, water supply and forest products. However, available well-dated records resolving the Holocene interannual-to-decadal variability from this region are only available for the past ~ 1000 years. Here we present a new, accurately dated high-resolution speleothem record for the past ~ 4000 years from Oregon Caves National Monument (OCNM) in southwestern Oregon. Stalagmite OCNM-02-1 has an average growth rate of 10 μ /year and was removed from the cave in the 1930's . Previous studies indicate that OCNM speleothems are responding to environmental changes above the cave and are suitable for paleoclimate research [Turgeon and Lundberg, 2004; Vacco, et al., 2005]. We used a New Wave micromill to sample stalagmite OCNM-02-1 at 30 μm intervals, resulting in an average resolution of ~ 3 years. Using δ18O and δ13C we address questions of long-term variations in interannual and decadal climate change in the Pacific Northwest, and we compare the speleothem climate reconstruction with available proxies in the western United States.

  3. High-resolution Sr/Ca records in sclerosponges calibrated to temperature in situ

    NASA Astrophysics Data System (ADS)

    Rosenheim, Brad E.; Swart, Peter K.; Thorrold, Simon R.; Willenz, Philippe; Berry, Lorraine; Latkoczy, Christopher

    2004-02-01

    Ratios of strontium to calcium have been analyzed by laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) in a skeletal section of the sclerosponge Ceratoporella nicholsoni. The growth period, representative of 3 yr, was stained in the skeleton with a fluorochrome (calcein). Temperatures were recorded at 2 h intervals within the shallow, cryptic reef enclosure that the sclerosponge inhabited on the northern coast of Jamaica, allowing the formulation of a direct empirical relationship between Sr/Ca and temperature. To verify this calibration, Sr/Ca ratios of two sclerosponges of the same species from depths of 67 m and 136 m in Exuma Sound, Bahamas, were analyzed by LA-ICP-MS and compared to the temperatures from these depths over a decade prior to collection. The result is an independently verified, high-resolution empirical calibration for the temperature sensitivity of Sr/Ca ratios in the aragonite skeletons of sclerosponges from Jamaica and the Bahamas. The calibration is a first for C. nicholsoni and indicates that sclerosponges are more sensitive temperature recorders than zooxanthellate corals. It represents an important step in establishing skeletal geochemistry of sclerosponges as a proxy of temperature in the upper 250 m of the ocean.

  4. A geochemical high-resolution record of late Holocene droughts from western-central Mexico

    NASA Astrophysics Data System (ADS)

    Sosa, S.; Lozano-Garcia, S.; Roy, P.; Caballero, M.

    2013-05-01

    We present a model of change in precipitation over the late Holocene from Santa Maria del Oro Lake (SMO) located at the western end of central Mexico. The present day precipitation in the region is associated mainly to the Mexican Monsoon and ENSO activity. This tropical site is characterized by 7 to 8 month long dry season between October and May. The model is based on high-resolution Titanium and Calcium concentrations data obtained by an ITRAX XRF core scanner and magnetic susceptibility of two 14C dated lacustrine sequences from the crater lake of SMO. The Ti record is a proxy indicator of runoff into the basin and we validated this record by comparing it with registers of historical droughts and tree ring chronologies. The geochemical data documents 4 different intervals of drought (i.e. 4000-3500, 3100-2050, 1750-1000 cal yr BP and last 120 years) and 3 wet periods (3500-3100, 2050-1750 and 1000-120 cal yr BP). The droughts were of different intensities and we identified a major drought during the Classic (0 to 1000 AD) with gradual increase in aridity towards the Epiclassic (800 to 1000 AD) that coincides with the Maya drought. The drought record at Santa Maria del Oro is compared with a record from the Cariaco basin indicating the latitudinal displacement of ITCZ and with the El Junco register of ENSO. Spectral analysis of the data indicates 50-year periodicities possibly related to solar activity and climatic forcings such as ENSO.

  5. Bighorn Basin Coring Project (BBCP): High-Resolution Continental Records of Early Paleogene Hyperthermals

    NASA Astrophysics Data System (ADS)

    Clyde, W.; Wing, S.; Gingerich, P.

    2012-04-01

    Hyperthermals like the Paleocene-Eocene Thermal Maximum (PETM) are transient global warming events associated with large negative carbon isotope excursions (CIEs) that may serve as analogs to present-day climate change. Determining the causes and effects of hyperthermals is important for understanding the long-term carbon cycle and its effects on other parts of the Earth system. Most detailed stratigraphic records of hyperthermals come from marine sediment cores (e.g. IODP) with relatively few well-resolved continental stratigraphic records available. The Bighorn Basin is an intermontane basin that formed during the Laramide orogeny and experienced rapid subsidence and aggradational fluvial deposition from the early Paleocene through the early Eocene (~65-50 million years ago). It preserves the most complete early Paleogene continental sequence in the world and includes an approximately 40-meter-thick PETM interval During the summer of 2011, over 900 meters of core were recovered as part of the Bighorn Basin Coring Project (BBCP). Two 6.2-cm diameter overlapping cores were drilled at each of three sites. Two of the sites (Basin Substation and Polecat Bench) target the PETM in different environments, and the third site (Gilmore Hill) targets the younger and smaller hyperthermals known as ETM2 and H2. The BBCP cores make it possible to develop high-resolution (circa 1000-year) proxy records of climate change, carbon cycling, and biotic change from unweathered material to investigate the response of a terrestrial depositional and ecological system to extreme global warming events. The coring localities are also distributed along a transect from the margin to the axis of the basin to compare the tectonic and depositional effects on the hyperthermal records. Down-hole logs, multi-sensor core logs (magnetic susceptibility and color reflectance), visual core descriptions, and preliminary isotopic samples will be evaluated, with special emphasis on correlation to previous

  6. High-resolution record of the Laschamp geomagnetic excursion at the Blake-Bahama Outer Ridge

    NASA Astrophysics Data System (ADS)

    Bourne, Mark D.; Mac Niocaill, Conall; Thomas, Alex L.; Henderson, Gideon M.

    2013-12-01

    Geomagnetic excursions are brief deviations of the geomagnetic field from behaviour expected during `normal secular' variation. The Laschamp excursion at ˜41 ka was one such deviation. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity associated with this excursion. Accurate dating of excursions, and determination of their durations from multiple locations, is vital to our understanding of global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites, 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172). High sedimentation rates (˜30-40 cm kyr-1) at these locations allow determination of transitional field behaviour during the excursion. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. We determine the age and duration of the Laschamp excursion using a stratigraphy linked to the δ18O record from the Greenland ice cores. This chronology dates the Laschamp excursion at the Blake Ridge to 41.3 ka. The excursion is characterized by rapid transitions (less than 200 yr) between stable normal polarity and a partially reversed polarity state. The palaeointensity record is in good agreement between the two sites, revealing two prominent minima. The first minimum is associated with the Laschamp excursion at 41 ka and the second corresponds to the Mono Lake excursion at ˜35.5 ka. We determine that the directional excursion during the Laschamp at this location was no longer than ˜400 yr, occurring within a palaeointensity minimum that lasted 2000 yr. The Laschamp excursion at this location is much shorter in duration than the Blake and Iceland Basin excursions.

  7. The AAO's Gemini High-Resolution Optical SpecTrograph (GHOST) concept

    NASA Astrophysics Data System (ADS)

    Ireland, Michael J.; Barnes, Stuart; Cochrane, David; Colless, Matthew; Connor, Peter; Horton, Anthony; Gibson, Steve; Lawrence, Jon; Martell, Sarah; McGregor, Peter; Nicolle, Tom; Nield, Kathryn; Orr, David; Robertson, J. G.; Ryder, Stuart; Sheinis, Andrew; Smith, Greg; Staszak, Nick; Tims, Julia; Xavier, Pascal; Young, Peter; Zheng, Jessica

    2012-09-01

    The Gemini High-Resolution Optical SpecTrograph (GHOST) will fill an important gap in the current suite of Gemini instruments. We will describe the Australian Astronomical Observatory (AAO)-led concept for GHOST, which consists of a multi-object, compact, high-efficiency, fixed-format, fiber-fed design. The spectrograph itself is a four-arm variant of the asymmetric white-pupil echelle Kiwispec spectrograph, Kiwisped, produced by Industrial Research Ltd. This spectrograph has an R4 grating and a 100mm pupil, and separate cross-disperser and camera optics for each of the four arms, carefully optimized for their respective wavelength ranges. We feed this spectrograph with a miniature lensletbased IFU that sub-samples the seeing disk of a single object into 7 hexagonal sub-images, reformatting this into a slit with a second set of double microlenses at the spectrograph entrance with relatively little loss due to focal-ratio degradation. This reformatting enables high spectral resolution from a compact design that fits well within the relatively tight GHOST budget. We will describe our baseline 2-object R~50,000 design with full wavelength coverage from the ultraviolet to the silicon cutoff, as well as the high-resolution single-object R~75,000 mode.

  8. Ship detection for high resolution optical imagery with adaptive target filter

    NASA Astrophysics Data System (ADS)

    Ju, Hongbin

    2015-10-01

    Ship detection is important due to both its civil and military use. In this paper, we propose a novel ship detection method, Adaptive Target Filter (ATF), for high resolution optical imagery. The proposed framework can be grouped into two stages, where in the first stage, a test image is densely divided into different detection windows and each window is transformed to a feature vector in its feature space. The Histograms of Oriented Gradients (HOG) is accumulated as a basic feature descriptor. In the second stage, the proposed ATF highlights all the ship regions and suppresses the undesired backgrounds adaptively. Each detection window is assigned a score, which represents the degree of the window belonging to a certain ship category. The ATF can be adaptively obtained by the weighted Logistic Regression (WLR) according to the distribution of backgrounds and targets of the input image. The main innovation of our method is that we only need to collect positive training samples to build the filter, while the negative training samples are adaptively generated by the input image. This is different to other classification method such as Support Vector Machine (SVM) and Logistic Regression (LR), which need to collect both positive and negative training samples. The experimental result on 1-m high resolution optical images shows the proposed method achieves a desired ship detection performance with higher quality and robustness than other methods, e.g., SVM and LR.

  9. High-resolution temperature sensing in the Dead Sea using fiber optics

    NASA Astrophysics Data System (ADS)

    Arnon, A.; Lensky, N. G.; Selker, J. S.

    2014-02-01

    The thermal stratification of the Dead Sea was observed in high spatial and temporal resolution by means of fiber-optics temperature sensing. The aim of the research was to employ the novel high-resolution profiler in studying the dynamics of the thermal structure of the Dead Sea and the related processes including the investigation of the metalimnion fluctuations. The 18 cm resolution profiling system was placed vertically through the water column supported by a buoy 450 m from shore, from 2 m above to 53 m below the water surface (just above the local seafloor), covering the entire seasonal upper layer (the metalimnion had an average depth of ˜20 m). Temperature profiles were recorded every 5 min. The May to July 2012 data set allowed quantitative investigation of the thermal morphology dynamics, including objective definitions of key locations within the metalimnion based on the temperature depth profile and its first and second depth derivatives. Analysis of the fluctuation of the defined metalimnion locations showed strong anticorrelation to measured sea level fluctuations. The slope of the sea level versus metalimnion depth was found to be related to the density ratio of the upper layer and the underlying main water body, according to the prediction of a two-layer model. The heat content of the entire water column was calculated by integrating the temperature profiles. The vertically integrated apparent heat content was seen to vary by 50% in a few hours. These fluctuations were not correlated to the atmospheric heat fluxes, nor to the momentum transfer, but were highly correlated to the metalimnion and the sea level fluctuations (r = 0.84). The instantaneous apparent heat flux was 3 orders of magnitude larger than that delivered by radiation, with no direct correlation to the frequency of radiation and wind in the lake. This suggests that the source of the momentary heat flux is lateral advection due to internal waves (with no direct relation to the diurnal

  10. High-resolution stable carbon isotope record of the Permian to earliest Triassic from East Greenland

    NASA Astrophysics Data System (ADS)

    Sanson Barrera, Anna; Hochuli, Peter A.; Bucher, Hugo; Meier, Maximiliano; Schneebeli Hermann, Elke; Weissert, Helmut; Bernasconi, Stefano M.

    2013-04-01

    The Late Permian and Early Triassic organic carbon isotope records show global major excursions probably triggered by episodic volcanic degasing of the Siberian Large Igneous Province. Important and rapid fluctuations of the global carbon cycle are also reflected in the biosphere. The geological record seems to comprise several major floral and marine faunal turnovers indicating short-lived biotic recoveries. In northwest Pangea, the active Early Triassic Greenland - Norway rifting system led to the accommodation of thick sedimentary sequences. This basin has a great potential for detailed studies of regional and global biotic and climatic changes with high temporal resolution during this critical interval in Earth's history. The western part of this basin is exposed in north-eastern Greenland and is represented by a succession of deltaic sediments organized in a general regressive trend ranging throughout the Griesbachian and the onset of the Dienerian. On the eastern side of the basin the succession has been drilled off the Norwegian coast. On Hold with Hope (East Greenland, 74°N) up to ca. 800m thick sections of the ammonoid-bearing Early Triassic Wordie Creek Formation have been logged and sampled. Here we present a high-resolution organic carbon isotope record and preliminary palynofacies data of a 500m thick composite section ranging from the Permian into the earliest Triassic. The organic carbon isotope record is closely comparable to the coeval section from the Trøndelag platform in Mid-Norway. The two records show a first major negative shift (ca. -6‰) representing the unconformity between the Ravnefjeld and the Wordie Creek formations, regionally known as the lithological Permian-Triassic boundary. Higher up, a second negative shift of ca. -4‰ correlates with the carbon shift associated with the GSSP Permian-Triassic boundary as defined at Meishan (China), represented by carbon isotope values around -30‰. This negative shift is followed by a

  11. A high-resolution optical see-through head-mounted display with eyetracking capability.

    PubMed

    Hua, Hong; Hu, Xinda; Gao, Chunyu

    2013-12-16

    A head-mounted display system with fully-integrated eyetracking capability offers multi-fold benefits, not only to fundamental scientific research but also to emerging applications of such technology. A key limitation of the state-of-the-art eyetracked head-mounted display (ET-HMD) technology is the lack of compactness and portability. In this paper, we present an innovative design of a high resolution optical see-through ET-HMD system based on freeform optical technology. A prototype system is demonstrated, which offers a goggle-like compact form factor, non-obstructive see-through field of view and true high-definition image resolution for the virtual display. The see-through view, via the combination of a freeform prism and corrector, achieved better than 0.5 arc minute of angular resolution for the central region of approximately 40-degrees to ensure minimal impacts on the see-through vision of an HMD user.

  12. A high-resolution fiber optic accelerometer based on intracavity phase-generated carrier (PGC) modulation

    NASA Astrophysics Data System (ADS)

    Lin, Qiao; Chen, Liuhua; Li, Shu; Wu, X.

    2011-01-01

    A compact-size fiber optic accelerometer was designed to achieve both high resolution and wide dynamic range concurrently. An optical cavity, with its length modulated by a piezoelectric oscillator at audio frequency, is utilized to resolve the nanometer-level displacement of a silicon micro-mirror which serves as an inertial mass for acceleration sensing. Strain analysis of the proof-mass flexure structure by Cosmosworks was carried out to calculate responsivity and resonance frequency for a comparison with experimental measurement. The responsivity below the structural resonance frequency of 160 Hz reaches 36 dB re 1 rad/g. Performance measurement demonstrated that the accelerometer was able to resolve an acceleration of 48 ng Hz-1/2 with a dynamic range of 2 × 107.

  13. KiwiSpec - an advanced spectrograph for high resolution spectroscopy: optical design and variations

    NASA Astrophysics Data System (ADS)

    Barnes, Stuart I.; Gibson, Steve; Nield, Kathryn; Cochrane, Dave

    2012-09-01

    The KiwiSpec R4-100 is an advanced high resolution spectrograph developed by KiwiStar Optics, Industrial Research Ltd, New Zealand. The instrument is based around an R4 echelle grating and a 100mm collimated beam diameter. The optical design employs a highly asymmetric white pupil design, whereby the transfer collimator has a focal length only 1/3 that of the primary collimator. This allows the cross-dispersers (VPH gratings) and camera optics to be small and low cost while also ensuring a very compact instrument. The KiwiSpec instrument will be bre-fed and is designed to be contained in both thermal and/or vacuum enclosures. The instrument concept is highly exible in order to ensure that the same basic design can be used for a wide variety of science cases. Options include the possibility of splitting the wavelength coverage into 2 to 4 separate channels allowing each channel to be highly optimized for maximum eciency. CCDs ranging from smaller than 2K2K to larger than 4K4K can be accommodated. This allows good (3-4 pixel) sampling of resolving powers ranging from below 50,000 to greater than 100,000. Among the specic design options presented here will be a two-channel concept optimized for precision radial velocities, and a four-channel concept developed for the Gemini High- Resolution Optical Spectrograph (GHOST). The design and performance of a single-channel prototype will be presented elsewhere in these proceedings.

  14. A High Resolution Record of Ocean Circulation since the last Interglacial from Nd isotopes

    NASA Astrophysics Data System (ADS)

    Goldstein, S. L.; Piotrowski, A. M.; Hemming, S. R.; Fairbanks, R. G.; Zylberberg, D. R.

    2004-12-01

    The variability of the global conveyor through ice ages has been a matter of dispute due to different indications from different paleocirculation proxies. Nd isotopes in marine precipitates conservatively reflect water mass mixing along their transport paths, and are changed only by addition of a new component of Nd. We present the first high resolution Nd isotope record of paleocirculation between MIS 1 and 5c from Cape Basin cores RC11-83 and TNO57-21. The record indicates a strong conveyer during warm northern hemisphere interglacial and interstadial intervals, and a weaker one during glacials and stadial intervals. The pattern of changes varies with Greenland paleotemperature. A first quantification attempt indicates that NADW export during the LGM was half the magnitude of the early Holocene. The strengthening through Termination 1 covaries with Greenland temperature and North Atlantic sea ice coverage. It markedly weakens between the Bolling and Younger Dryas. The weakening during the MIS 5a/4 transition is sharp, occurring within 1 ka. Throughout MIS 3 short-term maxima are associated with prominent interstadials in Greenland ice records (8, 12, 14, 17). Local minima at ~40 and ~62 ka may be associated with Heinrich events 4 and 6. During the ice age initiation and termination, global carbon budget shifts preceded circulation changes, and these were preceded by ice sheet growth during the initiation. There is no apparent lead-lag during interstadial warmings. The observations allow for ocean circulation to be a trigger of major climate change during abrupt events that are not driven by orbital forcing. At major glacial-interglacial boundaries, the global carbon budget and thermohaline ocean circulation both respond to the climate changes that forced the growth and decline of continental ice sheets. Overall the data show that Nd isotope ratios can be a powerful tool to trace paleocirculation history.

  15. High-resolution in-depth imaging of optically cleared thick samples using an adaptive SPIM

    PubMed Central

    Masson, Aurore; Escande, Paul; Frongia, Céline; Clouvel, Grégory; Ducommun, Bernard; Lorenzo, Corinne

    2015-01-01

    Today, Light Sheet Fluorescence Microscopy (LSFM) makes it possible to image fluorescent samples through depths of several hundreds of microns. However, LSFM also suffers from scattering, absorption and optical aberrations. Spatial variations in the refractive index inside the samples cause major changes to the light path resulting in loss of signal and contrast in the deepest regions, thus impairing in-depth imaging capability. These effects are particularly marked when inhomogeneous, complex biological samples are under study. Recently, chemical treatments have been developed to render a sample transparent by homogenizing its refractive index (RI), consequently enabling a reduction of scattering phenomena and a simplification of optical aberration patterns. One drawback of these methods is that the resulting RI of cleared samples does not match the working RI medium generally used for LSFM lenses. This RI mismatch leads to the presence of low-order aberrations and therefore to a significant degradation of image quality. In this paper, we introduce an original optical-chemical combined method based on an adaptive SPIM and a water-based clearing protocol enabling compensation for aberrations arising from RI mismatches induced by optical clearing methods and acquisition of high-resolution in-depth images of optically cleared complex thick samples such as Multi-Cellular Tumour Spheroids. PMID:26576666

  16. High-resolution in-depth imaging of optically cleared thick samples using an adaptive SPIM

    NASA Astrophysics Data System (ADS)

    Masson, Aurore; Escande, Paul; Frongia, Céline; Clouvel, Grégory; Ducommun, Bernard; Lorenzo, Corinne

    2015-11-01

    Today, Light Sheet Fluorescence Microscopy (LSFM) makes it possible to image fluorescent samples through depths of several hundreds of microns. However, LSFM also suffers from scattering, absorption and optical aberrations. Spatial variations in the refractive index inside the samples cause major changes to the light path resulting in loss of signal and contrast in the deepest regions, thus impairing in-depth imaging capability. These effects are particularly marked when inhomogeneous, complex biological samples are under study. Recently, chemical treatments have been developed to render a sample transparent by homogenizing its refractive index (RI), consequently enabling a reduction of scattering phenomena and a simplification of optical aberration patterns. One drawback of these methods is that the resulting RI of cleared samples does not match the working RI medium generally used for LSFM lenses. This RI mismatch leads to the presence of low-order aberrations and therefore to a significant degradation of image quality. In this paper, we introduce an original optical-chemical combined method based on an adaptive SPIM and a water-based clearing protocol enabling compensation for aberrations arising from RI mismatches induced by optical clearing methods and acquisition of high-resolution in-depth images of optically cleared complex thick samples such as Multi-Cellular Tumour Spheroids.

  17. Repeated, noninvasive, high resolution spectral domain optical coherence tomography imaging of zebrafish embryos

    PubMed Central

    Kagemann, Larry; Ishikawa, Hiroshi; Zou, Jian; Charukamnoetkanok, Puwat; Wollstein, Gadi; Townsend, Kelly A.; Gabriele, Michelle L.; Bahary, Nathan; Wei, Xiangyun; Fujimoto, James G.

    2008-01-01

    Purpose To demonstrate a new imaging method for high resolution spectral domain optical coherence tomography (SD-OCT) for small animal developmental imaging. Methods Wildtype zebrafish that were 24, 48, 72, and 120 h post fertilization (hpf) and nok gene mutant (48 hpf) embryos were imaged in vivo. Three additional embryos were imaged twice, once at 72 hpf and again at 120 hpf. Images of the developing eye, brain, heart, whole body, proximal yolk sac, distal yolk sac, and tail were acquired. Three-dimensional OCT data sets (501×180 axial scans) were obtained as well as oversampled frames (8,100 axial scans) and repeated line scans (180 repeated frames). Scan volumes ranged from 750×750 µm to 3×3 mm, each 1.8 mm thick. Three-dimenstional data sets allowed construction of C-mode slabs of the embryo. Results SD-OCT provided ultra-high resolution visualization of the eye, brain, heart, ear, and spine of the developing embryo as early as 24 hpf, and allowed development to be documented in each of these organ systems in consecutive sessions. Repeated line scanning with averaging optimized the visualization of static and dynamic structures contained in SD-OCT images. Structural defects caused by a mutation in the nok gene were readily observed as impeded ocular development, and enlarged pericardial cavities. Conclusions SD-OCT allowed noninvasive, in vivo, ultra-high resolution, high-speed imaging of zebrafish embryos in their native state. The ability to measure structural and functional features repeatedly on the same specimen, without the need to sacrifice, promises to be a powerful tool in small animal developmental imaging. PMID:19052656

  18. High-resolution speleothem record of precipitation from the Yucatan Peninsula spanning the Maya Preclassic Period

    NASA Astrophysics Data System (ADS)

    Medina-Elizalde, Martín; Burns, Stephen J.; Polanco-Martínez, Josué M.; Beach, Timothy; Lases-Hernández, Fernanda; Shen, Chuan-Chou; Wang, Hao-Cheng

    2016-03-01

    We produced a new high-resolution absolute U-Th dated stalagmite oxygen isotope record (δ18O) from Río Secreto, Playa del Carmen, Yucatan Peninsula (YP). This new 1434-year stalagmite record (named Itzamna after the Maya god of creation) spans the time interval between BCE 1037 and CE 397 with an average resolution of 8 ± 2 years. It provides a novel view of climate evolution over the Preclassic and early Classic periods in Maya history. To understand the controls of regional precipitation δ18O on seasonal time scales, we characterized the amount effect between precipitation amount (P) and precipitation δ18O (δP). We found that precipitation δ18O in the Yucatan Peninsula is controlled by the amount effect on seasonal scales (δP/ΔP = - 0.0137 ± 0.0031‰ per mm, r = 0.9), as suspected but never before demonstrated. Cave drip δ18O is consistent with the annual amount-weighted δ18O composition of precipitation. Multiple lines of evidence suggest that stalagmite δ18O reflects isotopic equilibrium conditions and thus stalagmite δ18O changes are interpreted to reflect precipitation amount. We determined quantitative precipitation changes from the stalagmite δ18O record following previous methods (Medina-Elizalde and Rohling, 2012). The stalagmite precipitation record suggests twelve periods of anomalous precipitation reductions ranging between about 30 and 70% below mean conditions at the time and with durations from 6 years to 31 years. Between BCE 520 and 166, the speleothem precipitation record suggests that the YP experienced an interval of high precipitation labeled the Late Preclassic Humid Period (LPHP) with precipitation maxima of up to + 86 ± 20%. Preclassic Maya cultural expansion in El Mirador Basin, located in northern Guatemala, took place while the peninsula transitioned from the LPHP to an interval with below average precipitation. We find that the Preclassic abandonment of major centers in the Mirador Basin and others around the Maya

  19. Development of a flexible optical fiber based high resolution integrated PET/MRI system

    SciTech Connect

    Yamamoto, Seiichi; Watabe, Hiroshi; Kanai, Yasukazu; Watabe, Tadashi; Aoki, Masaaki; Sugiyama, Eiji; Kato, Katsuhiko; Hatazawa, Jun

    2012-11-15

    Purpose: The simultaneous measurement of PET and magnetic resonance imaging (MRI) is an emerging field for molecular imaging research. Although optical fiber based PET/MRI systems have advantages on less interference between PET and MRI, there is a drawback in reducing the scintillation light due to the fiber. To reduce the problem, the authors newly developed flexible optical fiber bundle based block detectors and employed them for a high resolution integrated PET/MRI system. Methods: The flexible optical fiber bundle used 0.5 mm diameter, 80 cm long double clad fibers which have dual 12 mm Multiplication-Sign 24 mm rectangular inputs and a single 24 mm Multiplication-Sign 24 mm rectangular output. In the input surface, LGSO scintillators of 0.025 mol.% (decay time: {approx}31 ns: 0.9 mm Multiplication-Sign 1.3 mm Multiplication-Sign 5 mm) and 0.75 mol.% (decay time: {approx}46 ns: 0.9 mm Multiplication-Sign 1.3 mm Multiplication-Sign 6 mm) were optically coupled in depth direction to form depth-of-interaction detector, arranged in 11 Multiplication-Sign 13 matrix and optically coupled to the fiber bundle. The two inputs of the bundle are bent for 90 Degree-Sign , bound to one, and are optically coupled to a Hamamatsu 1-in. square position sensitive photomultiplier tube. Results: Light loss due to the fiber bundle could be reduced and the performance of the block detectors was improved. Eight optical fiber based block detectors (16 LGSO blocks) were arranged in a 56 mm diameter ring to form a PET system. Spatial resolution and sensitivity were 1.2 mm full-width at half-maximum and 1.2% at the central field-of-view, respectively. Sensitivity change was less than 1% for 2 Degree-Sign C temperature changes. This PET system was integrated with a 0.3 T permanent magnet MRI system which has 17 cm diameter hole at the yoke area for insertion of the PET detector ring. There was no observable interference between PET and MRI. Simultaneous imaging of PET and MRI was

  20. Multimodal adaptive optics for depth-enhanced high-resolution ophthalmic imaging

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Mujat, Mircea; Iftimia, Nicusor V.; Lue, Niyom; Ferguson, R. Daniel

    2010-02-01

    We developed a multimodal adaptive optics (AO) retinal imager for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa (RP). The development represents the first ever high performance AO system constructed that combines AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. The SSOCT channel operates at a wavelength of 1 μm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. The system is designed to operate on a broad clinical population with a dual deformable mirror (DM) configuration that allows simultaneous low- and high-order aberration correction. The system also includes a wide field line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation; an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of rotational eye motion; and a high-resolution LCD-based fixation target for presentation to the subject of stimuli and other visual cues. The system was tested in a limited number of human subjects without retinal disease for performance optimization and validation. The system was able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 μm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve targets deep into the choroid. In addition to instrument hardware development, analysis algorithms were developed for efficient information extraction from clinical imaging sessions, with functionality including automated image registration, photoreceptor counting, strip and montage stitching, and segmentation. The system provides clinicians and researchers with high-resolution, high performance adaptive optics imaging to help

  1. Ultra-high resolution Fourier domain optical coherence tomography for old master paintings.

    PubMed

    Cheung, C S; Spring, M; Liang, H

    2015-04-20

    In the last 10 years, Optical Coherence Tomography (OCT) has been successfully applied to art conservation, history and archaeology. OCT has the potential to become a routine non-invasive tool in museums allowing cross-section imaging anywhere on an intact object where there are no other methods of obtaining subsurface information. While current commercial OCTs have shown potential in this field, they are still limited in depth resolution (> 4 μm in paint and varnish) compared to conventional microscopic examination of sampled paint cross-sections (~1 μm). An ultra-high resolution fiber-based Fourier domain optical coherence tomography system with a constant axial resolution of 1.2 μm in varnish or paint throughout a depth range of 1.5 mm has been developed. While Fourier domain OCT of similar resolution has been demonstrated recently, the sensitivity roll-off of some of these systems are still significant. In contrast, this current system achieved a sensitivity roll-off that is less than 2 dB over a 1.2 mm depth range with an incident power of ~1 mW on the sample. The high resolution and sensitivity of the system makes it convenient to image thin varnish and glaze layers with unprecedented contrast. The non-invasive 'virtual' cross-section images obtained with the system show the thin varnish layers with similar resolution in the depth direction but superior clarity in the layer interfaces when compared with conventional optical microscope images of actual paint sample cross-sections obtained micro-destructively. PMID:25969057

  2. High resolution Holocene sea ice records from Herald Canyon, Chukchi Sea

    NASA Astrophysics Data System (ADS)

    Pearce, Christof; Jakobsson, Martin; O'Regan, Matt; Rattray, Jayne; Barrientos, Natalia; Muchitiello, Francesco; Smittenburg, Rienk; Cronin, Tom; Coxall, Helen; Semiletov, Igor

    2016-04-01

    Arctic Ocean sea ice plays a critical role in the Earth's climate system because of the positive ice-albedo feedback mechanisms as well as its control on ocean-atmospheric heat exchange and potential influence on the thermohaline circulation. Key to improving our understanding of Arctic sea ice cover and its reaction to external forcing is the reconstruction of past variability through paleo-records such as marine sediment cores. Although the observed recent sea ice loss seems to be the strongest of the last millennia, it is still uncertain whether the shift from perennial to seasonal ice cover expected for the near future was unprecedented during the current interglacial. High resolution sea ice reconstructions from the Arctic Ocean are rare, and specifically records from the Russian Arctic are underrepresented. In this study, we present results from marine sediment cores from the Herald Canyon in the East Siberian Sea. The area is one of the major conduits of Pacific water entering the Arctic Ocean basin from the Bering Strait and is thus an ideal place to study past variability of the inflow of these nutrient rich waters. Radiocarbon dating of mollusks indicates very high sedimentation rates at the coring sites which allowed for analyses at centennial resolution up to decadal resolution in the late Holocene. Core samples were analyzed for the biomarker IP25, which is produced by diatoms living in sea ice and is used as a proxy of past seasonal sea ice concentrations. Preliminary results indicate the presence of seasonal sea ice during the entire Late Holocene and show a significant increase of sea ice concentrations during the last millennia.

  3. High resolution Holocene sea ice records from Herald Canyon, East Siberian Sea

    NASA Astrophysics Data System (ADS)

    Pearce, C.; Rattray, J.; Jakobsson, M.; Barrientos, N.; Muschitiello, F.; Smittenberg, R.; O'Regan, M.; Coxall, H.

    2015-12-01

    Arctic Ocean sea ice plays a critical role in the Earth's climate system because of the positive ice-albedo feedback mechanisms as well as its control on ocean-atmospheric heat exchange and potential influence on the thermohaline circulation. Key to improving our understanding of Arctic sea ice cover and its reaction to external forcing is the reconstruction of past variability through paleo-records such as marine sediment cores. Although the observed recent sea ice loss seems to be the strongest of the last millennia, it is still uncertain whether the shift from perennial to seasonal ice cover expected for the near future was unprecedented during the current interglacial. High resolution sea ice reconstructions from the Arctic Ocean are rare, and specifically records from the Russian Arctic are underrepresented. In this study, we present results from marine sediment cores from the Herald Canyon in the East Siberian Sea. The area is one of the major conduits of Pacific water entering the Arctic Ocean basin from the Bering Strait and is thus an ideal place to study past variability of the inflow of these nutrient rich waters. Radiocarbon dating of mollusks indicates very high sedimentation rates at the coring sites which allowed for analyses at centennial resolution up to decadal resolution in the late Holocene. Core samples were analyzed for the biomarker IP25, which is produced by diatoms living in sea ice and is used as a proxy of past seasonal sea ice concentrations. Preliminary results indicate the presence of seasonal sea ice during the entire Late Holocene and show a significant increase of sea ice concentrations during the last millennia.

  4. High resolution Antarctic glaciochemical climate proxy records and their global implications

    NASA Astrophysics Data System (ADS)

    Dixon, Daniel Arthur

    2011-12-01

    The first section of this study presents major ion, trace element, heavy metal, rare earth element and oxygen isotope data from a series of surface snow samples and shallow firn sections collected along four US ITASE traverses across extensive regions of East and West Antarctica. In each sample the dissolved major ion, total trace element, and delta18 O concentrations are measured. This provides a baseline from which changes in the chemistry of the atmosphere over Antarctica can be monitored under expected warming scenarios and continued intensification of industrial activities in the Southern Hemisphere. Satellite remote sensing measurements of microwave backscatter and grain size assist in the identification of glaze/dune areas across Antarctica and show how chemical concentrations are higher in these areas, precluding them from containing useful high-resolution chemical climate records. The majority of the non-glaze/dune samples in this study exhibit similar, or lower, concentrations to those from previous studies. Consequently, the results presented here comprise a conservative baseline for Antarctic surface snow chemical concentrations. The second section of this study presents a 200-year proxy for Northerly Air Mass Incursions (NAMI) into central and western West Antarctica. The NAMI proxy is developed from the examination of 19 shallow (21m -- 150m deep) Antarctic ice core non-sea-salt (nss) Ca2+ concentration records and it exhibits a significant rise in recent decades. This rise is unprecedented for at least the last 200 years and is coincident with anthropogenically-driven changes in other large-scale Southern Hemisphere (SH) environmental phenomena such as greenhouse gas induced warming, ozone depletion and the associated intensification of the SH westerlies. Statistical analysis suggests that atmospheric circulation is the dominant factor affecting nssCa2+ concentrations throughout central and western West Antarctica.

  5. High Resolution Active Optics Observations from the Kepler Follow-up Observation Program

    NASA Astrophysics Data System (ADS)

    Gautier, Thomas N.; Ciardi, D. R.; Marcy, G. W.; Hirsch, L.

    2014-01-01

    The ground based follow-up observation program for candidate exoplanets discovered with the Kepler observatory has supported a major effort for high resolution imaging of candidate host stars using adaptive optics wave-front correction (AO), speckle imaging and lucky imaging. These images allow examination of the sky as close as a few tenths of an arcsecond from the host stars to detect background objects that might be the source of the Kepler transit signal instead of the host star. This poster reports on the imaging done with AO cameras on the Keck, Palomar 5m and Shane 3m (Lick Observatory) which have been used to obtain high resolution images of over 500 Kepler Object of Interest (KOI) exoplanet candidate host stars. All observations were made at near infrared wavelengths in the J, H and K bands, mostly using the host target star as the AO guide star. Details of the sensitivity to background objects actually attained by these observations and the number of background objects discovered are presented. Implications to the false positive rate of the Kepler candidates are discussed.

  6. Flood monitoring in a semi-arid environment using spatially high resolution radar and optical data.

    PubMed

    Seiler, Ralf; Schmidt, Jana; Diallo, Ousmane; Csaplovics, Elmar

    2009-05-01

    The geographic term "Niger Inland Delta" stands for a vast plain of approximately 40,000 km(2), which is situated in the western Sahel (Republic of Mali). The Inland Delta is affected by yearly inundation through the variable water levels of the Niger-Bani river system. Due to a good availability of (surface) water, the ecosystem at the Niger Inland Delta serves as resting place stop-over for many migrating birds and other wildlife species as well as economic base for farmers and pastoral people. To foster the sustainable usage of its natural resources and to protect this natural heritage, the entire Niger Inland Delta became RAMSAR site in 2004. This paper aims to test to which extent texture analysis can improve the quality of flood monitoring in a semi-arid environment using spatially high resolution ASAR imaging mode data. We found the Gray Level Dependence Method (GLDM) was most suitable proceeding for our data. Several statistical parameters were calculated via co-occurrence matrices and were used to classify the images in different gradation of soil moisture classes. In a second step we used additional information from spatially high resolution optical data (ASTER) to improve the separability of open water areas from moisture/vegetated areas.

  7. An adaptive optics imaging system based on a high-resolution liquid crystal on silicon device.

    PubMed

    Mu, Quanquan; Cao, Zhaoliang; Hu, Lifa; Li, Dayu; Xuan, Li

    2006-09-01

    An adaptive optics imaging system is introduced in this paper. A high resolution liquid crystal on silicon (LCOS) device was used as a phase only wave front corrector instead of a conversional deformable mirror. The wave front aberration was detected by a Shack-Hartmann (SH) wave front sensor, which has lambda/100 rms wave front measurement accuracy. Under this construction 0.09lambda (lambda=0.6328microm) Peak to Valley correction precision was reached. Further more, some low frequency hot convection turbulence induced by an electric iron was compensated in real time at the same precision. The Modulation Transfer Function (MTF) of this system was also measured before and after wave front correction. Under the active correction of LCOS, the system reached the diffraction limited resolution approximately 65l p/mm on the horizontal direction. All of this showed the ability of using this device in high resolution, low temporal turbulence imaging system, such as retinal imaging, to improve the resolution performance.

  8. High resolution Holocene paleomagnetic secular variation records from Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Usapkar, A.; Dewangan, P.; Badesab, F. K.; Mazumdar, A.; Ramprasad, T.; Krishna, K. S.; Basavaiah, N.

    2016-03-01

    We present high resolution paleosecular variation (PSV) records up to 8 cal. kyr BP from three piston cores, MD161/8, MD161/11 and MD161/13 acquired in the Krishna-Godavari (KG) basin, Bay of Bengal. During the Holocene period, high sedimentation rates are recorded at MD161/8 (38.8-248.3 cm/kyr), MD161/11 (137-336 cm/kyr) and MD161/13 (∼573 cm/kyr). Rock magnetic data analysis suggests that the remanence signal is carried by titanomagnetite/titanohematite grains in stable single domain (SSD)/pseudo single domain (PSD) state. The PSV records of MD161/11 and MD161/13 show good correlation in the uppermost sediments despite significant variation in the sedimentation rates; however, poor correlation of PSV records is observed for the core MD161/8 probably due to local effects. Paleoinclination records of MD161/8, MD161/11 and MD161/13 show a low between ∼2.4 and 2.0 cal. kyr BP, an increase between 2.0 and 1.4 cal. kyr BP and a decrease towards the present. To varying degrees these trends can be observed in the other Asian PSV records of Shuangchiling (SCL) and Biwa lakes. However, the magnitude of the observed inclination anomaly in KG basin is higher (∼40°) compared to those reported from SCL (∼25°) and Biwa (∼10°) lakes. Paleodeclination records of MD161/11 and MD161/13 show a decline between ∼4.0 and 2.9 cal. kyr BP, an increase between 2.9 and 2.1 cal. kyr BP, a substantial decrease between ∼2.1 and 1.0 cal. kyr BP and an increase towards the present. Similar trends can be observed in the other Asian PSV records of SCL and Biwa lakes with a minor age offset of 0.2-0.5 kyr. The available models CALS7k.2 and CALS10k.1 are evaluated for their capability in predicting the inclination and declination anomalies from the Asian regions. The CALS7k.2 model can predict most of the inclination anomalies while the CALS10k.1 is unable to predict many of them. The CALS7k.2 model shows that the observed inclination anomalies can be attributed to the presence of

  9. A high-resolution speleothem record of western equatorial Pacific rainfall: Implications for Holocene ENSO evolution

    NASA Astrophysics Data System (ADS)

    Chen, Sang; Hoffmann, Sharon S.; Lund, David C.; Cobb, Kim M.; Emile-Geay, Julien; Adkins, Jess F.

    2016-05-01

    coupled air-sea dynamics that are sensitive to precessional insolation forcing. Isolating the exact mechanisms that drive long-term ENSO evolution will require additional high-resolution paleoclimatic reconstructions and further investigation of Holocene tropical climate evolution using coupled climate models.

  10. A New High-Resolution Record of the Blake Geomagnetic Excursion from ODP Site 1062

    NASA Astrophysics Data System (ADS)

    Bourne, M. D.; Mac Niocaill, C.; Henderson, G. M.; Thomas, A. L.; Faurschou Knudsen, M.

    2010-12-01

    We present a high resolution record of the Blake geomagnetic excursion from Ocean Drilling Program (ODP) Site 1062 on the Blake-Bahama Outer Ridge. The excursion is recorded in three separate cores, with the high sedimentation rate (~10 cm/ka) at this location allowing the determination of transitional field behaviour during the excursion. A complex geometry is observed for the excursional geomagnetic field at the site. The directional records show an initial deviation from the expected directions across an interval of 1 m that achieves a completely reversed state, and then returns to normal polarity. A second, although less well-defined, short-lived phase of anomalous directions is observed immediately following the first event in two of the three cores. Measurements of the magnetic susceptibility show little variation through the core indicating that the concentration and grain size of the remanence carriers remain relatively constant during the studied interval. Measurements of the S-Ratio and remanence coercivity also remain constant through the sections of interest, and indicate magnetite to be the primary remanence carrier. The relatively homogeneous sediment enables the determination of two relative palaeointensity proxies by normalizing natural remanent magnetization measurements using artificially induced magnetizations (anhysteretic remanence, ARM and isothermal remanence, IRM). These records are consistent between all three cores. The relative palaeointensity proxies suggest that the Earth's magnetic field decreased substantially in intensity several tens of kyr prior to the initial event, before reaching an intensity minimum coinciding with the directional excursion maximum. A second palaeointensity minimum is also observed after the excursional event with no associated directional change. These features are consistent with global palaeointensity stacks. Our age model uses a new oxygen isotope stratigraphy. However, rather than assuming a constant

  11. High-resolution palaeomagnetic records of the Laschamp geomagnetic excursion from the Blake Ridge

    NASA Astrophysics Data System (ADS)

    Mac Niocaill, C.; Bourne, M. D.; Thomas, A. L.; Henderson, G. M.

    2013-05-01

    Geomagnetic excursions are brief (1000s of years) deviations in geomagnetic field behaviour from that expected during 'normal secular' variation. The Laschamp excursion (~41 ka) was a global deviation in geomagnetic field behaviour. Previously published records suggest rapid changes in field direction and a concurrent substantial decrease in field intensity. Accurate dating of excursions and determinations of their durations from multiple locations is vital to our understanding to global field behaviour during these deviations. We present here high-resolution palaeomagnetic records of the Laschamp excursion obtained from two Ocean Drilling Program (ODP) Sites 1061 and 1062 on the Blake-Bahama Outer Ridge (ODP Leg 172) Relatively high sedimentation rates (~30-40 cm kyr-1) at these locations allow the determination of transitional field behaviour during the excursion. Despite their advantages, sedimentary records can be limited by the potential for unrecognized variations in sedimentation rates between widely spaced age-constrained boundaries. Rather than assuming a constant sedimentation rate between assigned age tie-points, we employ measurements of the concentration of 230Thxs in the sediment. 230Thxs is a constant flux proxy and may be used to assess variations in the sedimentation rates through the core sections of interest. Following this approach, we present a new age model for Site 1061 that allows us to better determine the temporal behaviour of the Laschamp excursion with greater accuracy and known uncertainty. Palaeomagnetic measurements of discrete samples from four cores reveal a single excursional feature, across an interval of 30 cm, associated with a broader palaeointensity low. The excursion is characterised by rapid transitions (less than 200 years) between a stable normal polarity and a partially-reversed, polarity. Peaks in inclination either side of the directional excursion indicate periods of time when the local field is dominated by vertical

  12. A comparison of high resolution optical and radio observations of W3

    NASA Technical Reports Server (NTRS)

    Dickel, H. R.; Harten, R. H.; Gull, T. R.

    1983-01-01

    High resolution maps of the W3 complex for radio continuum and selected optical emission lines are used to derive the visual extinction A(V), the excitation, and the evolutionary state of the component H II regions. A large diffuse H II region in the east, which is the most highly evolved of this type, is found, together with a southern complex of H II regions and a northern complex of young and compact H II regions still embedded in the W3 molecular core. A comparison of the observed dust distribution with ionized and atomic hydrogen and several other molecules in W3 shows the functional relationship between the C-130 column density and A(V) to be in accord with Strohacker's (1978) result for dark clouds.

  13. Optical coherence tomography for high-resolution imaging of mouse development in utero

    NASA Astrophysics Data System (ADS)

    Syed, Saba H.; Larin, Kirill V.; Dickinson, Mary E.; Larina, Irina V.

    2011-04-01

    Although the mouse is a superior model to study mammalian embryonic development, high-resolution live dynamic visualization of mouse embryos remain a technical challenge. We present optical coherence tomography as a novel methodology for live imaging of mouse embryos through the uterine wall thereby allowing for time lapse analysis of developmental processes and direct phenotypic analysis of developing embryos. We assessed the capability of the proposed methodology to visualize structures of the living embryo from embryonic stages 12.5 to 18.5 days postcoitus. Repetitive in utero embryonic imaging is demonstrated. Our work opens the door for a wide range of live, in utero embryonic studies to screen for mutations and understand the effects of pharmacological and toxicological agents leading to birth defects.

  14. A low-cost, high-resolution, video-rate imaging optical radar

    SciTech Connect

    Sackos, J.T.; Nellums, R.O.; Lebien, S.M.; Diegert, C.F.; Grantham, J.W.; Monson, T.

    1998-04-01

    Sandia National Laboratories has developed a unique type of portable low-cost range imaging optical radar (laser radar or LADAR). This innovative sensor is comprised of an active floodlight scene illuminator and an image intensified CCD camera receiver. It is a solid-state device (no moving parts) that offers significant size, performance, reliability, and simplicity advantages over other types of 3-D imaging sensors. This unique flash LADAR is based on low cost, commercially available hardware, and is well suited for many government and commercial uses. This paper presents an update of Sandia`s development of the Scannerless Range Imager technology and applications, and discusses the progress that has been made in evolving the sensor into a compact, low, cost, high-resolution, video rate Laser Dynamic Range Imager.

  15. Evaluating Corneal Collagen Organization Using High Resolution Non Linear Optical (NLO) Macroscopy*

    PubMed Central

    Jester, James V.; Winkler, Moritz; Jester, Bryan E.; Nien, Chyong; Chai, Dongyul; Brown, Donald J.

    2010-01-01

    Purpose Recent developments in non-linear optical (NLO) imaging using femtosecond lasers provides a non-invasive method for detecting collagen fibers by imaging second harmonic generated (SHG) signals. However, this technique is limited by the small field of view (FoV) necessary to generate SHG signals. The purpose of this report is to review our efforts to greatly extend the FoV in order to assess the entire collagen structure using high resolution macroscopic (HRMac) imaging. Methods Intact human eyes were fixed under pressure and the whole cornea (13 mm diameter) excised and embedded in low melting point agar for vibratome sectioning (200–300 μm). Sections were then optically scanned using a Zeiss LSM 510 Meta and Chameleon femtosecond laser to generate SHG images. For each vibratome section, an overlapping series of 3-D data sets (466 × 466 × 150 μm) were taken covering the entire tissue (15 mm × 6 mm area) using a motorized, mechanical stage. The 3-D data sets were then concatenated to generate an NLO based tomograph. Results HRMac of the cornea yielded large macroscopic (80 Meg Pixels per plane), 3-dimensional tomographs with high resolution (0.81 μm later, 2.0 μm axial) in which individual collagen fibers (stromal lamellae) could be traced, segmented and extracted. 3-D reconstructions suggested that the anterior cornea is comprised of highly intertwined lamellae that insert into the anterior limiting lamina (Bowman’s Layer). Conclusion We conclude that HRMac using NLO based tomography provides a powerful new tool to assess collagen structural organization within the cornea. PMID:20724856

  16. High Resolution Environmental Magnetic Study of a Holocene Sedimentary Record from Zaca Lake, Ca

    NASA Astrophysics Data System (ADS)

    Platzman, E. S.; Lund, S.; Kirby, M. E.; Feakins, S. J.

    2012-12-01

    Magnetic studies of Holocene lake sediments recovered from Zaca lake have yielded a 3000-year high resolution record of environmental variability and paleolimnology. Zaca lake is a small oligomictic lake ~12m deep situated 730 m above sea level in the steep canyons of the San Rafael mountains, NW of Santa Barbara. Throughout much of the year Zaca lake is anaerobic below 7m. Hydrogen sulfide, fed into the lake via runoff and local sulphur springs, is present throughout the hypolimnion with concentrations sometime exceeding 30 mg/ l. During the summer months when the lake is stratified, light colored carbonate rich microlaminae are formed; and often during the winter months when the lake overturns, killing the anaerobic bacteria, black microlamina rich in iron sulfide are deposited on the lake floor, creating a stratigraphy reflecting patterns of environmental variability on annual to millennial scales. Samples for magnetic analysis were obtained from 8.5 m of core recovered from the central region of Zaca lake. Ages, constrained using radiocarbon chronostratigraphy, yielded sedimentation rates of 2-10 mm/yr with an average rate of 3 mm per yr over the 3000 yr interval. Parameters reflecting decadal scale variability in magnetic concentration (susceptibility, ARM, SIRM) and grainsize (ARM/Chi) were measured every 2 cm. Additional rock magnetic tests, including thermal demagnetization of three component IRM, were applied at selected intervals to constrain the magnetic mineralogy. These data were combined with analyses of clastic grain size, % calcium carbonate and % organics to create a multiproxy record of environmental variability. Results show that Zaca lake has had a complex depositional history. Anthropogenic effects associated with European colonization are present in the upper meters. Most notable, however, is a dramatic shift in the magnetic parameters and mineralogy between the upper and lower half of the core (circa 1300 ybp) indicating a shift in regime

  17. UDECON: deconvolution optimization software for restoring high-resolution records from pass-through paleomagnetic measurements

    NASA Astrophysics Data System (ADS)

    Xuan, Chuang; Oda, Hirokuni

    2015-11-01

    The rapid accumulation of continuous paleomagnetic and rock magnetic records acquired from pass-through measurements on superconducting rock magnetometers (SRM) has greatly contributed to our understanding of the paleomagnetic field and paleo-environment. Pass-through measurements are inevitably smoothed and altered by the convolution effect of SRM sensor response, and deconvolution is needed to restore high-resolution paleomagnetic and environmental signals. Although various deconvolution algorithms have been developed, the lack of easy-to-use software has hindered the practical application of deconvolution. Here, we present standalone graphical software UDECON as a convenient tool to perform optimized deconvolution for pass-through paleomagnetic measurements using the algorithm recently developed by Oda and Xuan (Geochem Geophys Geosyst 15:3907-3924, 2014). With the preparation of a format file, UDECON can directly read pass-through paleomagnetic measurement files collected at different laboratories. After the SRM sensor response is determined and loaded to the software, optimized deconvolution can be conducted using two different approaches (i.e., "Grid search" and "Simplex method") with adjustable initial values or ranges for smoothness, corrections of sample length, and shifts in measurement position. UDECON provides a suite of tools to view conveniently and check various types of original measurement and deconvolution data. Multiple steps of measurement and/or deconvolution data can be compared simultaneously to check the consistency and to guide further deconvolution optimization. Deconvolved data together with the loaded original measurement and SRM sensor response data can be saved and reloaded for further treatment in UDECON. Users can also export the optimized deconvolution data to a text file for analysis in other software.

  18. High-resolution conodont oxygen isotope record of Ordovician climate change

    NASA Astrophysics Data System (ADS)

    Chen, J.; Chen, Z.; Algeo, T. J.

    2013-12-01

    The Ordovician Period was characterized by several major events, including a prolonged 'super greenhouse' during the Early Ordovician, the 'Great Ordovician Biodiversification Event (GOBE)' of the Middle and early Late Ordovician, and the Hirnantian ice age and mass extinction of the latest Ordovician (Webby et al., 2004, The Great Ordovician Biodiversification Event, Columbia University Press). The cause of the rapid diversification of marine invertebrates during the GOBE is not clear, however, and several scenarios have been proposed including widespread development of shallow cratonic seas, strong magmatic and tectonic activity, and climate moderation. In order to investigate relationships between climate change and marine ecosystem evolution during the Ordovician, we measured the oxygen isotopic composition of single coniform conodonts using a Cameca secondary ion mass spectrometer. Our δ18O profile shows a shift at the Early/Middle Ordovician transition that is indicative of a rapid 6 to 8 °C cooling. This cooling event marks the termination of the Early Ordovician 'super greenhouse' and may have established cooler tropical seawater temperatures that were more favorable for invertebrate animals, setting the stage for the GOBE. Additional cooling episodes occurred during the early Sandbian, early Katian, and Hirnantian, the last culminating in a short-lived (<1-Myr) end-Ordovician ice age. The much cooler conditions that prevailed at that time may have been an important factor in the end-Ordovician mass extinction. Our results differ from those of Trotter et al. (2008, 'Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry,' Science 321:550-554). Instead of a slow, protracted cooling through the Early and Middle Ordovician, our high-resolution record shows that cooling occurred in several discrete steps, with the largest step being at the Early/Middle Ordovician transition.

  19. Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology

    NASA Astrophysics Data System (ADS)

    Scherer, S.

    2009-04-01

    Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology S. Scherer1, E. Cristea1, O. Huber1, A. Krenn1 1 ALICONA GmbH Graz, Austria The need for increasing accuracy is a characteristic of all geo-applications, and hence of the instruments contributing to obtaining relevant data. Small and fine sensors are being developed, measuring different parameters of our geosystem and requiring continuous validation and calibration. These sensors have often very small components (fine sensors able to sense dust, atmospheric water vapour characteristics, pressure change, gravimeters, satellite micro-components), showing complex topographies including steep flanks and having varying reflective properties. In order to get valid and reliable results, quality assurance of these instruments and sensors is required. The optical technology Focus-Variation, developed by Alicona and added in the latest draft of the upcoming ISO standard 25178, provides high resolution 3D surface metrology even at those complex topographies. The technique of Focus-Variation combines the small depth of focus of an optical system with vertical scanning to provide topographical and color information from the variation of focus. It is used for high-resolution optical 3D surface measurements. The traceable and repeatable measurement results are further being used for calibration and validation purposes. Some of the characteristics of the technology are: - Measurement of instruments / samples with steep flanks up to 80° - Measurement of materials with strongly varying reflection properties - Measurement of surfaces presenting fine (from 10nm) or strong roughness Here, we present the operating principle and possible applications of the optical 3D measurement system "InfiniteFocus", which is based on the technology of Focus-Variation and used for quality assurance in the lab and in production. With the vertical resolution of up to 10nm, InfiniteFocus yields meaningful form and

  20. Multi-Sensor Fusion of Infrared and Electro-Optic Signals for High Resolution Night Images

    PubMed Central

    Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

    2012-01-01

    Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available. PMID:23112602

  1. [Study on an optical system of small ultraviolet imaging spectrometer with high resolution in broadband].

    PubMed

    Cong, Hai-Fang; Wang, Chun-Hui; Wang, Yu

    2013-02-01

    An ultraviolet imaging spectrometer was studied based on the principle of the small scale ultraviolet spectral instrument. The scheme composed of an off-axis parabolic mirror telescope and a single toroidal grating spectral imaging system was designed. The optimization of the optical system is the optimum processing for the parameters of the toroidal grating. The optical path function and the aberration equations of the grating were analyzed. The perfect anastigmatism conditions and imaging conditions of the single toroidal grating system were obtained. These two conditions that cannot be satisfied by the algebra calculation method limit the field of view and waveband of the spectrometer. The genetic algorithm was introduced to solve the problem. A solar-blind ultraviolet imaging spectrometer for 200-280 nm was designed to verify the design method. The optimum initial configuration was calculated and simulated. A system with F/# 5.7, focal length 102 mm and high spatial resolution was designed. The modulation transfer functions (MTF) of all fields of view are more than 0.65 in the waveband in the required Nyquist frequency (20 1p x mm(-1)). The design results indicate that the optical system theory can be applied to the small scale ultraviolet imaging spectrometer with high resolution and spectral broadband.

  2. Towards high-resolution retinal prostheses with direct optical addressing and inductive telemetry

    NASA Astrophysics Data System (ADS)

    Ha, Sohmyung; Khraiche, Massoud L.; Akinin, Abraham; Jing, Yi; Damle, Samir; Kuang, Yanjin; Bauchner, Sue; Lo, Yu-Hwa; Freeman, William R.; Silva, Gabriel A.; Cauwenberghs, Gert

    2016-10-01

    Objective. Despite considerable advances in retinal prostheses over the last two decades, the resolution of restored vision has remained severely limited, well below the 20/200 acuity threshold of blindness. Towards drastic improvements in spatial resolution, we present a scalable architecture for retinal prostheses in which each stimulation electrode is directly activated by incident light and powered by a common voltage pulse transferred over a single wireless inductive link. Approach. The hybrid optical addressability and electronic powering scheme provides separate spatial and temporal control over stimulation, and further provides optoelectronic gain for substantially lower light intensity thresholds than other optically addressed retinal prostheses using passive microphotodiode arrays. The architecture permits the use of high-density electrode arrays with ultra-high photosensitive silicon nanowires, obviating the need for excessive wiring and high-throughput data telemetry. Instead, the single inductive link drives the entire array of electrodes through two wires and provides external control over waveform parameters for common voltage stimulation. Main results. A complete system comprising inductive telemetry link, stimulation pulse demodulator, charge-balancing series capacitor, and nanowire-based electrode device is integrated and validated ex vivo on rat retina tissue. Significance. Measurements demonstrate control over retinal neural activity both by light and electrical bias, validating the feasibility of the proposed architecture and its system components as an important first step towards a high-resolution optically addressed retinal prosthesis.

  3. Results in coastal waters with high resolution in situ spectral radiometry: The Marine Optical System ROV

    NASA Astrophysics Data System (ADS)

    Yarbrough, Mark; Feinholz, Michael; Flora, Stephanie; Houlihan, Terrance; Johnson, B. Carol; Kim, Yong S.; Murphy, Marilyn Y.; Ondrusek, Michael; Clark, Dennis

    2007-09-01

    The water-leaving spectral radiance is a basic ocean color remote sensing parameters required for the vicarious calibration. Determination of water-leaving spectral radiance using in-water radiometry requires measurements of the upwelling spectral radiance at several depths. The Marine Optical System (MOS) Remotely Operated Vehicle (ROV) is a portable, fiber-coupled, high-resolution spectroradiometer system with spectral coverage from 340 nm to 960 nm. MOS was developed at the same time as the Marine Optical Buoy (MOBY) spectrometer system and is optically identical except that it is configured as a profiling instrument. Concerns with instrument self-shadowing because of the large exterior dimensions of the MOS underwater housing led to adapting MOS and ROV technology. This system provides for measurement of the near-surface upwelled spectral radiance while minimizing the effects of shadowing. A major advantage of this configuration is that the ROV provides the capability to acquire measurements 5 cm to 10 cm below the water surface and is capable of very accurate depth control (1 cm) allowing for high vertical resolution observations within the very near-surface. We describe the integrated system and its characterization and calibration. Initial measurements and results from observations of coral reefs in Kaneohe Bay, Oahu, extremely turbid waters in the Chesapeake Bay, Maryland, and in Case 1 waters off Southern Oahu, Hawaii are presented.

  4. Improved fusing infrared and electro-optic signals for high-resolution night images

    NASA Astrophysics Data System (ADS)

    Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

    2012-06-01

    Electro-optic (EO) images exhibit the properties of high resolution and low noise level, while it is a challenge to distinguish objects with infrared (IR), especially for objects with similar temperatures. In earlier work, we proposed a novel framework for IR image enhancement based on the information (e.g., edge) from EO images. Our framework superimposed the detected edges of the EO image with the corresponding transformed IR image. Obviously, this framework resulted in better resolution IR images that help distinguish objects at night. For our IR image system, we used the theoretical point spread function (PSF) proposed by Russell C. Hardie et al., which is composed of the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we designed an inverse filter based on the proposed PSF to transform the IR image. In this paper, blending the detected edge of the EO image with the corresponding transformed IR image and the original IR image is the principal idea for improving the previous framework. This improved framework requires four main steps: (1) inverse filter-based IR image transformation, (2) image edge detection, (3) images registration, and (4) blending of the corresponding images. Simulation results show that blended IR images have better quality over the superimposed images that were generated under the previous framework. Based on the same steps, the simulation result shows a blended IR image of better quality when only the original IR image is available.

  5. Multi-sensor fusion of infrared and electro-optic signals for high resolution night images.

    PubMed

    Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

    2012-01-01

    Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available.

  6. A New High-Resolution Record of the Blake Geomagnetic Excursion from ODP Site 1062

    NASA Astrophysics Data System (ADS)

    Bourne, Mark; Mac Niocaill, Conall; Henderson, Gideon; Thomas, Alex; Knudsen, Mads

    2010-05-01

    We present a high resolution record of the Blake geomagnetic excursion from Ocean Drilling Program (ODP) Site 1062 on the Blake-Bahama Outer Ridge. The excursion is recorded in three separate cores, with the high average sedimentation rate (10 cm ka-1) at this location allowing the determination of transitional field behaviour during the excursion. A complex geometry is observed for the excursional geomagnetic field. The directional records show an initial deviation from the expected directions across an interval of 1 m that achieves a completely reversed state, and then returns to normal polarity. A second, although less well-defined, short-lived phase of anomalous directions is observed immediately following the first event in two of the three cores. Measurements of the magnetic susceptibility show little variation through the core indicating that the concentration and grain size of the remanence carriers remains relatively constant throughout the studied interval. Measurements of the S-Ratio and remanence coercivity also remain constant through the core sections of interest, and indicate magnetite to be the primary remanence carrier. The relatively homogeneous sediment enables the determination of two relative palaeointensity proxies by normalizing natural remanent magnetization measurements using artificially induced magnetizations (anhysteretic remanence, ARM and isothermal remanence, IRM). These records are consistent between all three cores. The relative palaeointensity proxies suggest that the Earth's magnetic field decreased substantially in intensity up to 70 ka prior to the initial event, before reaching an intensity minimum coinciding with the directional excursion maximum. A second palaeointensity minimum is also observed after the excursional event with no associated directional change. These features are consistent with global palaeointensity stacks. A preliminary age model based on an oxygen isotope stratigraphy, and an average sedimentation rate

  7. High resolution record of the Last Glacial Maximum in eastern Australia

    NASA Astrophysics Data System (ADS)

    Petherick, Lynda; Moss, Patrick; McGowan, Hamish

    2010-05-01

    A continuous, high resolution (average ca. 22 year) record encompassing the Last Glacial Maximum (LGM) has been developed using multiple proxies (aeolian sediment flux, grain size, pollen and charcoal) in lake sediment from Tortoise Lagoon (TOR), North Stradbroke Island, Queensland, Australia. The presence of Asteraceae tubilifloreae and spineless Asteraceae (common indicators of glacial conditions in Australia) at TOR indicates significantly cooler temperatures (mean annual temperature up to 6oC lower than today). In addition to the palaeoclimatic reconstruction, a record of palaeodust transport pathways for eastern Australia was developed using ICP-MS trace element analysis and geochemical "fingerprinting" of TOR aeolian sediment to continental dust source areas. Vectors between dominant dust source areas and North Stradbroke Island allowed the reconstruction of the position and intensity of LGM dust transport pathways. Furthermore, changes in likely synpotic scale conditions can be postulated based on the position of the dust transport corridors. Similarities between the vegetation at TOR during the LGM and that at temperate sites e.g. Caledonia Fen, Victoria (Kershaw et al. 2007), Redhead Lagoon, New South Wales (Williams et al. 2006) and Barrington Tops, New South Wales (Sweller and Martin 2001) suggests that this record reflects regional conditions across southeastern Australia. The TOR record also correlates well with that from nearby Native Companion Lagoon which suggests that the LGM was actually an extended period of ca. 8 - 10 kyr, characterised by 2 periods of increased aridity (ca. 30 - 26.5 kyr and 21 - 19.5 kyr) (Petherick et al. 2008). A growing number of records from across the Southern Hemisphere e.g. New Zealand (Suggate and Almond 2003; Alloway et al. 2007; Newnham et al. 2007), Chile (Denton et al. 1999), Antarctica (Röthlisberger et al. 2002; EPICA 2006) and Australia (Smith 2009) also show evidence that the LGM encompassed a longer period of

  8. A new method of inshore ship detection in high-resolution optical remote sensing images

    NASA Astrophysics Data System (ADS)

    Hu, Qifeng; Du, Yaling; Jiang, Yunqiu; Ming, Delie

    2015-10-01

    Ship as an important military target and water transportation, of which the detection has great significance. In the military field, the automatic detection of ships can be used to monitor ship dynamic in the harbor and maritime of enemy, and then analyze the enemy naval power. In civilian field, the automatic detection of ships can be used in monitoring transportation of harbor and illegal behaviors such as illegal fishing, smuggling and pirates, etc. In recent years, research of ship detection is mainly concentrated in three categories: forward-looking infrared images, downward-looking SAR image, and optical remote sensing images with sea background. Little research has been done into ship detection of optical remote sensing images with harbor background, as the gray-scale and texture features of ships are similar to the coast in high-resolution optical remote sensing images. In this paper, we put forward an effective harbor ship target detection method. First of all, in order to overcome the shortage of the traditional difference method in obtaining histogram valley as the segmentation threshold, we propose an iterative histogram valley segmentation method which separates the harbor and ships from the water quite well. Secondly, as landing ships in optical remote sensing images usually lead to discontinuous harbor edges, we use Hough Transform method to extract harbor edges. First, lines are detected by Hough Transform. Then, lines that have similar slope are connected into a new line, thus we access continuous harbor edges. Secondary segmentation on the result of the land-and-sea separation, we eventually get the ships. At last, we calculate the aspect ratio of the ROIs, thereby remove those targets which are not ship. The experiment results show that our method has good robustness and can tolerate a certain degree of noise and occlusion.

  9. Optical design of the PEPSI high-resolution spectrograph at LBT

    NASA Astrophysics Data System (ADS)

    Andersen, Michael I.; Spano, Paolo; Woche, Manfred; Strassmeier, Klaus G.; Beckert, Erik

    2004-09-01

    PEPSI is a high-resolution, fiber fed echelle spectrograph with polarimetric capabilities for the LBT. In order to reach a maximum resolution R=120.000 in polarimetric mode and 300.000 in integral light mode with high efficiency in the spectral range 390-1050~nm, we designed a white-pupil configuration with Maksutov collimators. Light is dispersed by an R4 31.6 lines/mm monolithic echelle grating mosaic and split into two arms through dichroics. The two arms, optimized for the spectral range 390-550~nm and 550-1050~nm, respectively, consist of Maksutov transfer collimators, VPH-grism cross dispersers, optimized dioptric cameras and 7.5K x 7.5K 8~μ CCDs. Fibers of different core sizes coupled to different image-slicers allow a high throughput, comparable to that of direct feed instruments. The optical configuration with only spherical and cylindrical surfaces, except for one aspherical surface in each camera, reduces costs and guarantees high optical quality. PEPSI is under construction at AIP with first light expected in 2006.

  10. High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography

    DOEpatents

    Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.

    2010-09-07

    This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.

  11. Simultaneous high-resolution pH and spectrophotometric recordings of oxygen binding in blood microvolumes.

    PubMed

    Oellermann, Michael; Pörtner, Hans-O; Mark, Felix C

    2014-05-01

    Oxygen equilibrium curves have been widely used to understand oxygen transport in numerous organisms. A major challenge has been to monitor oxygen binding characteristics and concomitant pH changes as they occur in vivo, in limited sample volumes. Here we report a technique allowing highly resolved and simultaneous monitoring of pH and blood pigment saturation in minute blood volumes. We equipped a gas diffusion chamber with a broad-range fibre-optic spectrophotometer and a micro-pH optode and recorded changes of pigment oxygenation along oxygen partial pressure (PO2) and pH gradients to test the setup. Oxygen binding parameters derived from measurements in only 15 μl of haemolymph from the cephalopod Octopus vulgaris showed low instrumental error (0.93%) and good agreement with published data. Broad-range spectra, each resolving 2048 data points, provided detailed insight into the complex absorbance characteristics of diverse blood types. After consideration of photobleaching and intrinsic fluorescence, pH optodes yielded accurate recordings and resolved a sigmoidal shift of 0.03 pH units in response to changing PO2 from 0 to 21 kPa. Highly resolved continuous recordings along pH gradients conformed to stepwise measurements at low rates of pH changes. In this study we showed that a diffusion chamber upgraded with a broad-range spectrophotometer and an optical pH sensor accurately characterizes oxygen binding with minimal sample consumption and manipulation. We conclude that the modified diffusion chamber is highly suitable for experimental biologists who demand high flexibility, detailed insight into oxygen binding as well as experimental and biological accuracy combined in a single setup. PMID:24436387

  12. High-resolution full-field optical coherence tomography using high dynamic range image processing

    NASA Astrophysics Data System (ADS)

    Leong-Hoï, A.; Claveau, R.; Montgomery, P. C.; Serio, B.; Uhring, W.; Anstotz, F.; Flury, M.

    2016-04-01

    Full-field optical coherence tomography (FF-OCT) based on white-light interference microscopy, is an emerging noninvasive imaging technique for characterizing biological tissue or optical scattering media with micrometer resolution. Tomographic images can be obtained by analyzing a sequence of interferograms acquired with a camera. This is achieved by scanning an interferometric microscope objectives along the optical axis and performing appropriate signal processing for fringe envelope extraction, leading to three-dimensional imaging over depth. However, noise contained in the images can hide some important details or induce errors in the size of these details. To firstly reduce temporal and spatial noise from the camera, it is possible to apply basic image post processing methods such as image averaging, dark frame subtraction or flat field division. It has been demonstrate that this can improve the quality of microscopy images by enhancing the signal to noise ratio. In addition, the dynamic range of images can be enhanced to improve the contrast by combining images acquired with different exposure times or light intensity. This can be made possible by applying a hybrid high dynamic range (HDR) technique, which is proposed in this paper. High resolution tomographic analysis is thus performed using a combination of the above-mentioned image processing techniques. As a result, the lateral resolution of the system can be improved so as to approach the diffraction limit of the microscope as well as to increase the power of detection, thus enabling new sub-diffraction sized structures contained in a transparent layer, initially hidden by the noise, to be detected.

  13. High-resolution lidar observations of mesospheric sodium and implications for adaptive optics.

    PubMed

    Pfrommer, Thomas; Hickson, Paul

    2010-11-01

    Observations of sodium density variability in the upper mesosphere/lower thermosphere, obtained using a high-resolution lidar system, show rapid fluctuations in the sodium centroid altitude. The temporal power spectrum extends above 1 Hz and is well-fit by a power law having a slope that is -1.95±0.12. These fluctuations produce focus errors in adaptive optics systems employing continuous-wave sodium laser guide stars, which can be significant for large-aperture telescopes. For a 30 m aperture diameter, the associated rms wavefront error is approximately 4 nm per meter of altitude change and increases as the square of the aperture diameter. The vertical velocity of the sodium centroid altitude is found to be ~23 ms(-1) on a 1 s time scale. If these high-frequency fluctuations arise primarily from advection of horizontal structure by the mesospheric wind, our data imply that variations in the sodium centroid altitude on the order of tens of meters occur over the horizontal scales spanned by proposed laser guide star asterisms. This leads to substantial differential focus errors (~107 nm over a 1 arc min separation with a 30 m aperture diameter) that may impact the performance of wide-field adaptive optics systems. Short-lasting and narrow sodium density enhancements, more than 1 order of magnitude above the local sodium density, occur due to advection of meteor trails. These have the ability to change the sodium centroid altitude by as much as 1 km in less than 1 s, which could result in temporary disruption of adaptive optics systems.

  14. High-resolution flying-PIV with optical fiber laser delivery

    NASA Astrophysics Data System (ADS)

    Weichselbaum, Noah A.; André, Matthieu A.; Rahimi-Abkenar, Morteza; Manzari, Majid T.; Bardet, Philippe M.

    2016-05-01

    Implementation of non-intrusive optical measurement techniques, such as particle image velocimetry (PIV), in harsh environments requires specialized techniques for introducing controlled laser sheets to the region of interest. Large earthquake shake tables are a particularly challenging environment. Lasers must be mounted away from the table, and the laser sheet has to be delivered precisely and stably to the measurement station. Here, high-power multi-mode step-index fiber optics enable introduction of light from an Nd:YLF pulsed laser to a remote test section. Such lasers are suitable for coupling to optical fibers, which presents a portable, flexible, and safe manner to deliver a PIV light sheet. Best practices for their implementation are reviewed. Particular attention is focused on obtaining a collimated beam of acceptable quality at the output of the fiber. To achieve high spatial resolution, the PIV camera is directly mounted on the moving shake table with care to minimize its vibrations. A special arrangement of PIV planes is deployed for precise in-situ PIV alignment and to monitor and account for residual structure vibrations and beam wandering. The design of the instruments is detailed. Here, an experimental facility for the study of nuclear fuel bundle response to seismic forcing near prototypical conditions is instrumented. Only through integration of a high-resolution flying-PIV system can velocity fields be acquired. Data indicate that in the presence of a mean axial flow, a secondary oscillatory flow develops as the bundle oscillates. Instantaneous, phase-averaged, and fluctuating velocity fields illustrate this phenomenon.

  15. High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas

    SciTech Connect

    Brown, Charles M.; Seely, John F.; Feldman, Uri; Holland, Glenn E.; Weaver, James L.; Obenschain, Steven P.; Kjornrattanawanich, Benjawan; Fielding, Drew

    2008-10-15

    An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at (2/3) the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm{sup 2} square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm{sup 2} photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5x10{sup -7} J/nm from a plasma source area of 0.37 mm{sup 2} and with 0.4 ns time resolution.

  16. High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas.

    PubMed

    Brown, Charles M; Seely, John F; Feldman, Uri; Holland, Glenn E; Weaver, James L; Obenschain, Steven P; Kjornrattanawanich, Benjawan; Fielding, Drew

    2008-10-01

    An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at 23 the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm(2) square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm(2) photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5x10(-7) J/nm from a plasma source area of 0.37 mm(2) and with 0.4 ns time resolution.

  17. A system for optical high resolution screening of electrical excitable cells.

    PubMed

    Müller, Oliver; Tian, Qinghai; Zantl, Roman; Kahl, Valentin; Lipp, Peter; Kaestner, Lars

    2010-03-01

    The application of primary excitable cells for high content screening (HCS) requires a multitude of novel developments including cell culture and multi-well plates. Here we introduce a novel system combining optimised culture conditions of primary adult cardiomyocytes with the particular needs of excitable cells for arbitrary field stimulation of individual wells. The major advancements of our design were tested in calcium imaging experiments and comprise (i) each well of the plate can be subjected to individual pulse protocols, (ii) the software driving electrical stimulation can run as a stand-alone application but also as a plug-in in HCS software packages, (iii) the optical properties of the plastic substrate (foil) resemble those of glass coverslips fostering high resolution immersion-based microscopy, (iv) the bottom of the foil is coated with an oleophobic layer that prevents immersion oil from sticking, (v) the top of the foil is coated with an elastic film. The latter enables cardiomyocytes to display loaded contractions by mimicking the physiologically occurring local elastic network (e.g. extracellular matrix) and results in significantly increased contractions (with identical calcium transients) when compared to non-elastic substrates. Thus, our novel design and culture conditions represent an essential further step towards the application of primary cultured adult cardiomyocytes for HCS applications. PMID:20036001

  18. Measurement of ciliary beat frequency using ultra-high resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Chen, Jason J.; Jing, Joseph C.; Su, Erica; Badger, Christopher; Coughlan, Carolyn A.; Chen, Zhongping; Wong, Brian J. F.

    2016-02-01

    Ciliated epithelial cells populate up to 80% of the surface area of the human airway and are responsible for mucociliary transport, which is the key protective mechanism that provides the first line of defense in the respiratory tract. Cilia beat in a rhythmic pattern and may be easily affected by allergens, pollutants, and pathogens, altering ciliary beat frequency (CBF) subsequently. Diseases including cystic fibrosis, chronic obstructive pulmonary disease, and primary ciliary dyskinesia may also decrease CBF. CBF is therefore a critical component of respiratory health. The current clinical method of measuring CBF is phase-contrast microscopy, which involves a tissue biopsy obtained via brushing of the nasal cavity. While this method is minimally invasive, the tissue sample must be oriented to display its profile view, making the visualization of a single layer of cilia challenging. In addition, the conventional method requires subjective analysis of CBF, e.g., manually counting by visual inspection. On the contrary, optical coherence tomography (OCT) has been used to study the retina in ophthalmology as well as vasculature in cardiology, and offers higher resolution than conventional computed tomography and magnetic resonance imaging. Based on this technology, our lab specifically developed an ultra-high resolution OCT system to image the microstructure of the ciliated epithelial cells. Doppler analysis was also performed to determine CBF. Lastly, we also developed a program that utilizes fast Fourier transform to determine CBF under phase-contrast microscopy, providing a more objective method compared to the current method.

  19. High Resolution Imaging with Adaptive Optics at the Multiple Mirror Telescope

    NASA Astrophysics Data System (ADS)

    Lloyd-Hart, M.; McLeod, B. A.; Wittman, D.; Colucci, D.; McCarthy, D. W.; Angel, R.; Dekany, R.

    1992-12-01

    We present the latest results from an adaptive optics program being implemented at the MMT using a six element adaptive mirror. The tilt of the wavefront over each of the six telescopes is determined with a Shack-Hartmann type sensor using a 24times 24 pixel low-noise CCD. This system allows the MMT to operate at a resolution of 0.3'' at 2 microns -- near the diffraction limit of the individual 1.8-m telescopes. This resolution can be obtained within ~ 1' of any star with visual magnitude < 16, allowing high-resolution near-IR imaging with a NICMOS2 array of a wide variety of targets, including high-redshift galaxies and young and evolved stars. This system can also be used with the MMT operated as a phased array telescope. In this mode, the piston errors between the telescopes are determined by examining the Fourier transform of the combined 2-micron image of the natural guide star using a fast-readout InSb array. In this configuration we have achieved a resolution of 0.075''. In good seeing we expect to obtain images of interest within the isoplanatic patch of guide stars with K magnitude <7. We acknowledge financial support from the NSF (AST92-03336) and the Flintridge Foundation. The adaptive mirror was donated by ThermoTrex Corp.

  20. Ultra-high resolution water window x ray microscope optics design and analysis

    NASA Technical Reports Server (NTRS)

    Shealy, David L.; Wang, C.

    1993-01-01

    This project has been focused on the design and analysis of an ultra-high resolution water window soft-x-ray microscope. These activities have been accomplished by completing two tasks contained in the statement of work of this contract. The new results from this work confirm: (1) that in order to achieve resolutions greater than three times the wavelength of the incident radiation, it will be necessary to use spherical mirror surfaces and to use graded multilayer coatings on the secondary in order to accommodate the large variations of the angle of incidence over the secondary when operating the microscope at numerical apertures of 0.35 or greater; (2) that surface contour errors will have a significant effect on the optical performance of the microscope and must be controlled to a peak-to-valley variation of 50-100 A and a frequency of 8 periods over the surface of a mirror; and (3) that tolerance analysis of the spherical Schwarzschild microscope has been shown that the water window operations will require 2-3 times tighter tolerances to achieve a similar performance of operations with 130 A radiation. These results have been included in a manuscript included in the appendix.

  1. A system for optical high resolution screening of electrical excitable cells.

    PubMed

    Müller, Oliver; Tian, Qinghai; Zantl, Roman; Kahl, Valentin; Lipp, Peter; Kaestner, Lars

    2010-03-01

    The application of primary excitable cells for high content screening (HCS) requires a multitude of novel developments including cell culture and multi-well plates. Here we introduce a novel system combining optimised culture conditions of primary adult cardiomyocytes with the particular needs of excitable cells for arbitrary field stimulation of individual wells. The major advancements of our design were tested in calcium imaging experiments and comprise (i) each well of the plate can be subjected to individual pulse protocols, (ii) the software driving electrical stimulation can run as a stand-alone application but also as a plug-in in HCS software packages, (iii) the optical properties of the plastic substrate (foil) resemble those of glass coverslips fostering high resolution immersion-based microscopy, (iv) the bottom of the foil is coated with an oleophobic layer that prevents immersion oil from sticking, (v) the top of the foil is coated with an elastic film. The latter enables cardiomyocytes to display loaded contractions by mimicking the physiologically occurring local elastic network (e.g. extracellular matrix) and results in significantly increased contractions (with identical calcium transients) when compared to non-elastic substrates. Thus, our novel design and culture conditions represent an essential further step towards the application of primary cultured adult cardiomyocytes for HCS applications.

  2. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    SciTech Connect

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  3. High-resolution spectroscopy using an acousto-optic tunable filter and a fiber-optic Fabry-Perot interferometer

    SciTech Connect

    Baldwin, D.P.; Zamzow, D.S.; DSilva, A.P.

    1996-04-01

    A compact, solid-state, high-resolution spectrometer consisting of an acousto-optic tunable filter (AOTF) and a fiber-optic Fabry{endash}Perot (FFP) interferometer has been developed. The system has been designed for high-resolution inductively coupled plasma atomic emission spectroscopy (ICP-AES) applications. A description of the AOTF-FFP and its performance is presented. The resolution of the AOTF-FFP was determined by measuring the physical widths of ICP emission lines using a 1.5-m-focal-length grating spectrometer and deconvoluting the physical line shapes from the acquired AOTF-FFP spectra. Over the optimum range of the FFP mirror coatings, the resolution is sufficient for the determination of isotopic and hyperfine emission features in ICP-AES experiments, and approaches that of the 1.5-m spectrometer. The application of the AOTF-FFP to the determination of uranium isotopes (U-235 and U-238) introduced into the ICP is presented. {copyright} {ital 1996 Society for Applied Spectroscopy.}

  4. Electrodynamics and energy characteristics of aurora at high resolution by optical methods

    NASA Astrophysics Data System (ADS)

    Dahlgren, H.; Lanchester, B. S.; Ivchenko, N.; Whiter, D. K.

    2016-06-01

    Technological advances leading to improved sensitivity of optical detectors have revealed that aurora contains a richness of dynamic and thin filamentary structures, but the source of the structured emissions is not fully understood. In addition, high-resolution radar data have indicated that thin auroral arcs can be correlated with highly varying and large electric fields, but the detailed picture of the electrodynamics of auroral filaments is yet incomplete. The Auroral Structure and Kinetics (ASK) instrument is a state-of-the-art ground-based instrument designed to investigate these smallest auroral features at very high spatial and temporal resolution, by using three electron multiplying CCDs in parallel for three different narrow spectral regions. ASK is specifically designed to utilize a new optical technique to determine the ionospheric electric fields. By imaging the long-lived O+ line at 732 nm, the plasma flow in the region can be traced, and since the plasma motion is controlled by the electric field, the field strength and direction can be estimated at unprecedented resolution. The method is a powerful tool to investigate the detailed electrodynamics and current systems around the thin auroral filaments. The two other ASK cameras provide information on the precipitation by imaging prompt emissions, and the emission brightness ratio of the two emissions, together with ion chemistry modeling, is used to give information on the energy and energy flux of the precipitating electrons. In this paper, we discuss these measuring techniques and give a few examples of how they are used to reveal the nature and source of fine-scale structuring in the aurora.

  5. Motor protein and microtubule mechanics: Application of a novel high-resolution optical trapping technique

    NASA Astrophysics Data System (ADS)

    Allersma, Miriam W.

    Using optical tweezers and a novel detection technique (a quadrant photodiode at the back focal plane or, BFP-QD), this thesis investigates two problems in biophysics, ncd motility and microtubule flexural rigidity. We use optically trapped microspheres to probe the samples. The technique detects the displacements of the microspheres relative to the trap center by monitoring the laser intensity shifts in the back focal plane of the microscope condenser. We use a quadrant diode to detect the shifts, which are due to far-field interference between the trapping laser and scattered laser light from the trapped object. The method yields high-resolution (nm-spatial and μsec-temporal), two-dimensional data, which is largely independent of trap position in the field of view. We first studied the motility of ncd, a kinesin-related motor protein. Motor proteins are able to harness the energy of ATP hydrolysis to perform mechanical work for the cell. Many ncd molecules were adsorbed onto silica microspheres and their motions along the microtubule surface lattice were observed with the BFP-QD method. Since the method is two-dimensional, we were able to monitor axial and lateral motions simultaneously. The average axial velocity was 230 +/- 30 nm/sec (average +/- SD). The high temporal resolution allowed us to investigate dynamical parameters. Spectral analysis showed an increase in viscous drag near the surface for ncd-driven microspheres. In addition, we found that the binding of the motors to microtubules in the presence of the nonhydrolyzable nucleotide adenylylimidodiphosphate caused an increase in the motor elastic constraint. Using a dual optical trap configuration in conjunction with the BFP-QD, we also investigated the elastic properties of taxol-stabilized microtubules. Cytoskeletal filaments are responsible for myriad structural cell functions. Our results were not readily interpreted by a standard bent strut treatment because of the finite size of the microspheres

  6. Fast, high-resolution 3D dosimetry utilizing a novel optical-CT scanner incorporating tertiary telecentric collimation.

    PubMed

    Sakhalkar, H S; Oldham, M

    2008-01-01

    This study introduces a charge coupled device (CCD) area detector based optical-computed tomography (optical-CT) scanner for comprehensive verification of radiation dose distributions recorded in nonscattering radiochromic dosimeters. Defining characteristics include: (i) a very fast scanning time of approximately 5 min to acquire a complete three-dimensional (3D) dataset, (ii) improved image formation through the use of custom telecentric optics, which ensures accurate projection images and minimizes artifacts from scattered and stray-light sources, and (iii) high resolution (potentially 50 microm) isotropic 3D dose readout. The performance of the CCD scanner for 3D dose readout was evaluated by comparison with independent 3D readout from the single laser beam OCTOPUS-scanner for the same PRESAGE dosimeters. The OCTOPUS scanner was considered the "gold standard" technique in light of prior studies demonstrating its accuracy. Additional comparisons were made against calculated dose distributions from the ECLIPSE treatment-planning system. Dose readout for the following treatments were investigated: (i) a single rectangular beam irradiation to investigate small field and very steep dose gradient dosimetry away from edge effects, (ii) a 2-field open beam parallel-opposed irradiation to investigate dosimetry along steep dose gradients, and (iii) a 7-field intensity modulated radiation therapy (IMRT) irradiation to investigate dosimetry for complex treatment delivery involving modulation of fluence and for dosimetry along moderate dose gradients. Dose profiles, dose-difference plots, and gamma maps were employed to evaluate quantitative estimates of agreement between independently measured and calculated dose distributions. Results indicated that dose readout from the CCD scanner was in agreement with independent gold-standard readout from the OCTOPUS-scanner as well as the calculated ECLIPSE dose distribution for all treatments, except in regions within a few

  7. Fast, high-resolution 3D dosimetry utilizing a novel optical-CT scanner incorporating tertiary telecentric collimation

    SciTech Connect

    Sakhalkar, H. S.; Oldham, M.

    2008-01-15

    This study introduces a charge coupled device (CCD) area detector based optical-computed tomography (optical-CT) scanner for comprehensive verification of radiation dose distributions recorded in nonscattering radiochromic dosimeters. Defining characteristics include: (i) a very fast scanning time of {approx}5 min to acquire a complete three-dimensional (3D) dataset, (ii) improved image formation through the use of custom telecentric optics, which ensures accurate projection images and minimizes artifacts from scattered and stray-light sources, and (iii) high resolution (potentially 50 {mu}m) isotropic 3D dose readout. The performance of the CCD scanner for 3D dose readout was evaluated by comparison with independent 3D readout from the single laser beam OCTOPUS-scanner for the same PRESAGE dosimeters. The OCTOPUS scanner was considered the 'gold standard' technique in light of prior studies demonstrating its accuracy. Additional comparisons were made against calculated dose distributions from the ECLIPSE treatment-planning system. Dose readout for the following treatments were investigated: (i) a single rectangular beam irradiation to investigate small field and very steep dose gradient dosimetry away from edge effects, (ii) a 2-field open beam parallel-opposed irradiation to investigate dosimetry along steep dose gradients, and (iii) a 7-field intensity modulated radiation therapy (IMRT) irradiation to investigate dosimetry for complex treatment delivery involving modulation of fluence and for dosimetry along moderate dose gradients. Dose profiles, dose-difference plots, and gamma maps were employed to evaluate quantitative estimates of agreement between independently measured and calculated dose distributions. Results indicated that dose readout from the CCD scanner was in agreement with independent gold-standard readout from the OCTOPUS-scanner as well as the calculated ECLIPSE dose distribution for all treatments, except in regions within a few millimeters of

  8. Development of a High-performance Optical System and Fluorescent Converters for High-resolution Neutron Imaging

    NASA Astrophysics Data System (ADS)

    Sakai, T.; Yasuda, R.; Iikura, H.; Nojima, T.; Matsubayashi, M.

    Two novel devices for use in neutron imaging technique are introduced. The first one is a high-performance optical lens for video camera systems. The lens system has a magnification of 1:1 and an F value of 3. The optical resolution is less than 5 μm. The second device is a high-resolution fluorescent plate that converts neutrons into visible light. The fluorescent converter material consists of a mixture of 6LiF and ZnS(Ag) fine powder, and the thickness of the converter is material is as little as 15 μm. The surface of the plate is coated with a 1 μm-thick gadolinium oxide layer. This layer is optically transparent and acts as an electron emitter for neutron detection. Our preliminary results show that the developed optical lens and fluorescent converter plates are very promising for high-resolution neutron imaging.

  9. Very High Resolution Solar X-ray Imaging Using Diffractive Optics

    NASA Technical Reports Server (NTRS)

    Dennis, B. R.; Skinner, G. K.; Li, M. J.; Shih, A. Y.

    2012-01-01

    This paper describes the development of X-ray diffractive optics for imaging solar flares with better than 0.1 arcsec angular resolution. X-ray images with this resolution of the greater than or equal to 10 MK plasma in solar active regions and solar flares would allow the cross-sectional area of magnetic loops to be resolved and the coronal flare energy release region itself to be probed. The objective of this work is to obtain X-ray images in the iron-line complex at 6.7 keV observed during solar flares with an angular resolution as fine as 0.1 arcsec - over an order of magnitude finer than is now possible. This line emission is from highly ionized iron atoms, primarily Fe xxv, in the hottest flare plasma at temperatures in excess of approximately equal to 10 MK. It provides information on the flare morphology, the iron abundance, and the distribution of the hot plasma. Studying how this plasma is heated to such high temperatures in such short times during solar flares is of critical importance in understanding these powerful transient events, one of the major objectives of solar physics.We describe the design, fabrication, and testing of phase zone plate X-ray lenses with focal lengths of approximately equal to 100 m at these energies that would be capable of achieving these objectives. We show how such lenses could be included on a two-spacecraft formation-flying mission with the lenses on the spacecraft closest to the Sun and an X-ray imaging array on the second spacecraft in the focal plane approximately equal to 100 m away. High resolution X-ray images could be obtained when the two spacecraft are aligned with the region of interest on the Sun. Requirements and constraints for the control of the two spacecraft are discussed together with the overall feasibility of such a formation-flying mission.

  10. Deriving High Resolution UV Aerosol Optical Depth over East Asia using CAI-OMI Joint Retrieval

    NASA Astrophysics Data System (ADS)

    Go, S.; Kim, J.; KIM, M.; Lee, S.

    2015-12-01

    Monitoring aerosols using near UV spectral region have been successfully performed over decades by Ozong Monitoring Instruments (OMI) with benefit of strong aerosol signal over continuous dark surface reflectance, both land and ocean. However, because of big foot print of OMI, the cloud contamination error was a big issue in the UV aerosol algorithm. In the present study, high resolution UV aerosol optical depth (AOD) over East Asia was derived by collaborating the Greenhouse gases Observing SATellite/Thermal And Near infrared Sensor for carbon Observation (GOSAT/TANSO)-Cloud and Aerosol Imager (CAI) and OMI together. AOD of 0.1 degree grid resolution was retrieved using CAI band 1 (380nm) by bring OMI lv.2 aerosol type, single scattering albedo, and aerosol layer peak height in 1 degree grid resolution. Collocation of the two dataset within the 0.5 degree grid with time difference of OMI and CAI less than 5 minute was selected. Selected region becomes wider as it goes to the higher latitude. Also, calculated degradation factor of 1.57 was applied to CAI band1 (380nm) by comparing normalized radiance and Lambertian Equivalent Reflectivity (LER) of both sensors. The calculated degradation factor was reasonable over dark scene, but inconsistent over cirrus cloud and bright area. Then, surface reflectance was developed by compositing CAI LER minimum data over three month period, since the infrequent sampling rate associated with the three-day recursion period of GOSAT and the narrow CAI swath of 1000 km. To retrieve AOD, look up table (LUT) was generated using radiative transfer model VLIDORT NGST. Finally, the retrieved AOD was validated with AERONET ground based measurement data during the Dragon-NE Asia campaign in 2012.

  11. Vertical and horizontal corneal epithelial thickness profiles determined by ultra-high resolution optical coherence tomography

    PubMed Central

    Du, Chixin; Wang, Jianhua; Cui, Lele; Shen, Meixiao; Yuan, Yimin

    2011-01-01

    Purpose To measure vertical and horizontal thickness profiles of the central and peripheral corneal epithelium and determine if daytime changes occur. Methods Forty eyes of 20 normal subjects were imaged by ultra-high resolution spectral domain optical coherence tomography to profile the corneal epithelial thickness from the edge of Bowman’s layer to the central cornea across the vertical and horizontal meridians. Measurements were made at 10:00 AM and again at 6, 8 hours later. Results The baseline vertical meridional epithelial thickness was thinnest, 42.9±4.1 μm, at the edge of Bowman’s layer in the superior region. It increased in thickness (p<0.01), towards the central cornea. The central epithelium averaged 52.5±2.4 μm, becoming thickest, 55.2±2.5 μm, in the inferior pericentral region. It thinned towards the inferior periphery, reaching 51.3±5.1 μm at the edge of Bowman’s layer (p<0.01). Along the horizontal meridian, the epithelium was thickest at the nasal side, 58.6±5.1 μm, and temporal side, 59.3±6.6 μm, near the edges of Bowman’s layer. It thinned towards the central cornea. There were no significant changes in the epithelial thickness at any location over 8 hours. Conclusion Epithelial thickness varied over the horizontal and vertical meridians and appeared stable during the daytime. PMID:22357393

  12. Insulated Conducting Cantilevered Nanotips and Two-Chamber Recording System for High Resolution Ion Sensing AFM

    NASA Astrophysics Data System (ADS)

    Meckes, Brian; Arce, Fernando Teran; Connelly, Laura S.; Lal, Ratnesh

    2014-03-01

    Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels.

  13. Insulated Conducting Cantilevered Nanotips and Two-Chamber Recording System for High Resolution Ion Sensing AFM

    PubMed Central

    Meckes, Brian; Arce, Fernando Teran; Connelly, Laura S.; Lal, Ratnesh

    2014-01-01

    Biological membranes contain ion channels, which are nanoscale pores allowing controlled ionic transport and mediating key biological functions underlying normal/abnormal living. Synthetic membranes with defined pores are being developed to control various processes, including filtration of pollutants, charge transport for energy storage, and separation of fluids and molecules. Although ionic transport (currents) can be measured with single channel resolution, imaging their structure and ionic currents simultaneously is difficult. Atomic force microscopy enables high resolution imaging of nanoscale structures and can be modified to measure ionic currents simultaneously. Moreover, the ionic currents can also be used to image structures. A simple method for fabricating conducting AFM cantilevers to image pore structures at high resolution is reported. Tungsten microwires with nanoscale tips are insulated except at the apex. This allows simultaneous imaging via cantilever deflections in normal AFM force feedback mode as well as measuring localized ionic currents. These novel probes measure ionic currents as small as picoampere while providing nanoscale spatial resolution surface topography and is suitable for measuring ionic currents and conductance of biological ion channels. PMID:24663394

  14. Optical design of an all-reflecting, high resolution camera for active-optics on ground-based telescopes

    NASA Astrophysics Data System (ADS)

    Richardson, E. H.; Morbey, C. L.

    Optical designs of high-resolution all-mirror cameras for the active optics of the 3.6-m Canada-France-Hawaii Telescope (CFHT) with classical optics (a paraboloidal primary), and the 2.2-m University of Hawaii telescope with Ritchey-Chretien (R-C) optics (a hyperboloidal primary), are presented. An oblate spheroid is used to produce longer focal ratios in the R-C telescope, lessening its disadvantage of a very small field of good definition at focal ratios longer than the optimized secondary focal ratio. Unlike the R-C telescope, the CFHT is not coma-free, and the prolate spheroid works well as its tertiary mirror. In the present camera design, the scale at the final focus is such that 0.25 arcsec covers 0.065 mm in order to match the resolution of the available detector. These cameras are off-axis, resulting in a slight change of magnification with the field rotation of alt-azimuth telescopes.

  15. Investigation of solar active regions at high resolution by balloon flights of the solar optical universal polarimeter, extended definition phase

    NASA Technical Reports Server (NTRS)

    Tarbell, Theodore D.

    1993-01-01

    Technical studies of the feasibility of balloon flights of the former Spacelab instrument, the Solar Optical Universal Polarimeter, with a modern charge-coupled device (CCD) camera, to study the structure and evolution of solar active regions at high resolution, are reviewed. In particular, different CCD cameras were used at ground-based solar observatories with the SOUP filter, to evaluate their performance and collect high resolution images. High resolution movies of the photosphere and chromosphere were successfully obtained using four different CCD cameras. Some of this data was collected in coordinated observations with the Yohkoh satellite during May-July, 1992, and they are being analyzed scientifically along with simultaneous X-ray observations.

  16. High-resolution frequency-domain second-harmonic optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Su, Jianping; Tomov, Ivan V.; Jiang, Yi; Chen, Zhongping

    2007-04-01

    We used continuum generated in an 8.5 cm long fiber by a femtosecond Yb fiber laser to improve threefold the axial resolution of frequency domain second-harmonic optical coherence tomography (SH-OCT) to 12 μm. The acquisition time was shortened by more than 2 orders of magnitude compared to the time-domain SH-OCT. The system was applied to image biological tissue of fish scales, pig leg tendon, and rabbit eye sclera. Highly organized collagen fibrils can be visualized in the recorded images. Polarization dependence on the SH has been used to obtain polarization resolved images.

  17. Non-harmonic analysis for high-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Chong, Changho; Cao, Xu; Morosawa, Atsushi; Totsuka, Koki; Suzuki, Takuya; Hirobayashi, Shigeki

    2010-02-01

    A novel processing technique called Non-Harmonic Analysis (NHA) is proposed for high-resolution OCT imaging. Conventional Fourier-Domain OCT relies on the FFT calculation which depends on the window function and length. NHA can resolve high frequency without being influenced by window function or frame length of sampled data. The results show that NHA process realizes practical image resolution equivalent to 100nm swept range by using significantly reduced wavelength range, and also implies the potential of high resolution imaging capability without the need of a broadband source.

  18. Observation and Analysis of High Resolution Optical Line Profiles in Comet Hyakutake (C/1996 B2)

    NASA Astrophysics Data System (ADS)

    Combi, M. R.; Cochran, A. L.

    1997-07-01

    Very high resolution (R=200,000) and high signal-to-noise echelle spectra were obtained of comet C/Hyakutake 1996 B2 using the 2DCoude spectrograph on the 2.7 m telescope at McDonald Observatory during late March and early April 1996. Doppler resolved profiles are presented for individual lines of most of the major optical neutral species: CN, C_2, O((1) D) at 6300{ Angstroms}, O((1) S) at 5577{ Angstroms} , NH_2, and H Balmer-alpha at 6563{ Angstroms}. These may be the first ever to be published for CN, C_2, and O((1) S). In all cases the instrument spectral function is smaller than the intrinsic line widths of the individual cometary lines, so the observations provide clear signatures of lines which are Doppler broadened by different combinations of the coma expansion, exothermic photochemical ejection speeds, and collisional thermalization. For modeling analysis of these data we have used a hybrid fluid/kinetic Monte Carlo approach which can realistically include all of the relevant physical/chemical processes important for shaping the spectral lines. Because of the very short lifetime of the NH_2 parent (NH_3), the NH_2 is collisionally thermalized and provides an excellent probe of the outflow of the expanding coma. Because O((1) D) atoms in the region sampled are produced mainly by the photodissociation of water and the resulting photon is a prompt emission, the line retains signatures of both the basic coma expansion velocity and the 1.6 km s(-1) ejection speed of the O({(1}) D) atoms. The O((1) S) profile is consistent with that for the O((1) D). The profiles of CN and C_2 are somewhat broadened (CN more so than C_2), compared with NH_2, and seem to require a combination of coma expansion and the exothermic ejection speed they receive upon their production. Although the H Balmer-alpha line is complicated by a chance coincidence of an H_2O(+) line and optical depth effects in the solar Lyman-beta which pumps the Balmer-alpha emission, the spread of the wings

  19. High-resolution Holocene South American monsoon history recorded by a speleothem from Botuverá Cave, Brazil

    NASA Astrophysics Data System (ADS)

    Bernal, J. P.; Cruz, Francisco W.; Stríkis, Nicolás M.; Wang, Xianfeng; Deininger, Michael; Catunda, Maria Carolina A.; Ortega-Obregón, C.; Cheng, Hai; Edwards, R. Lawrence; Auler, Augusto S.

    2016-09-01

    A Holocene stalagmite from Botuverá Cave, southeastern Brazil was analyzed by LA-ICPMS for Mg/Ca, Sr/Ca, Ba/Ca. The observed variability in the record was demonstrated to be modulated by prior calcite precipitation, and, thus, is interpreted to reflect monsoon intensity. We find that the calcite δ18O is strongly correlated with Sr/Ca, indicating that atmospheric circulation over South America and monsoon intensity have been tightly correlated throughout most of the Holocene, both directly responding to solar precession. Comparison with other contemporaneous high-resolution hydroclimate records reveals that SAMS has shown a degree of complexity during the Holocene not previously detected, with periods where the South American Convergence Zone (SACZ) expanded to cover most of the South American sub-continent, and coincident with periods of low-SST in the north Atlantic. We also detect periods where rainfall amount in northeastern and southeastern Brazil are markedly anti-phased, suggesting a north-south migration of SACZ, which it appears to be mediated by solar irradiance. The high-resolution nature of our record allow us to examine the effect that Holocene climate anomalies had upon SAMS dynamics and hydroclimate in southeastern Brazil, in particular the 8.2 ka event and the Little Ice Age. In addition to confirm the internal structure of the events, we also detect the possible consequences of the climatic anomalies upon ocean-atmosphere interactions through its effects upon SAMS.

  20. High resolution late Pliocene sea-surface temperature record from the northeast Atlantic Ocean

    USGS Publications Warehouse

    Dowsett, H.J.; Loubere, P.

    1992-01-01

    Application of quantitative micropaleontologic methods of sea-surface temperature (SST) estimation to the planktic foraminiferal faunas at Hole 548 in the northeast Atlantic between 3.5 and 2.0 Ma provide a detailed record of Pliocene surface temperature changes during the onset of major Northern Hemisphere glaciation. SST estimates indicate a relatively warm interval of "enhanced interglacials (warm peaks)" between 3.2 and 2.8 Ma followed by steady cooling with a significant step-like change toward colder temperatures occurring about 2.4 Ma. This record compares well with faunal and SST records from other North Atlantic sites. ?? 1992.

  1. Twentieth century sea-ice trends in the Ross Sea from a high-resolution, coastal ice-core record

    NASA Astrophysics Data System (ADS)

    Sinclair, Kate E.; Bertler, Nancy A. N.; Bowen, Melissa M.; Arrigo, Kevin R.

    2014-05-01

    We present the first proxy record of sea-ice area (SIA) in the Ross Sea, Antarctica, from a 130 year coastal ice-core record. High-resolution deuterium excess data show prevailing stable SIA from the 1880s until the 1950s, a 2-5% reduction from the mid-1950s to the early-1990s, and a 5% increase after 1993. Additional support for this reconstruction is derived from ice-core methanesulphonic acid concentrations and whaling records. While SIA has continued to decline around much of the West Antarctic coastline since the 1950s, concurrent with increasing air and ocean temperatures, the underlying trend is masked in the Ross Sea by a switch to positive SIA anomalies since the early-1990s. This increase is associated with a strengthening of southerly winds and the enhanced northward advection of sea ice.

  2. High-resolution 900 year volcanic and climatic record from the Vostok area, East Antarctica

    NASA Astrophysics Data System (ADS)

    Osipov, E. Y.; Khodzher, T. V.; Golobokova, L. P.; Onischuk, N. A.; Lipenkov, V. Y.; Ekaykin, A. A.; Shibaev, Y. A.; Osipova, O. P.

    2014-05-01

    Ion chromatography measurements of 1730 snow and firn samples obtained from three short cores and one pit in the Vostok station area, East Antarctica, allowed for the production of the combined volcanic record of the last 900 years (AD 1093-2010). The resolution of the record is 2-3 samples per accumulation year. In total, 24 volcanic events have been identified, including seven well-known low-latitude eruptions (Pinatubo 1991, Agung 1963, Krakatoa 1883, Tambora 1815, Huanaputina 1600, Kuwae 1452, El Chichon 1259) found in most of the polar ice cores. In comparison with three other East Antarctic volcanic records (South Pole, Plateau Remote and Dome C), the Vostok record contains more events within the last 900 years. The differences between the records may be explained by local glaciological conditions, volcanic detection methodology, and, probably, differences in atmospheric circulation patterns. The strongest volcanic signal (both in sulfate concentration and flux) was attributed to the AD 1452 Kuwae eruption, similar to the Plateau Remote and Talos Dome records. The average snow accumulation rate calculated between volcanic stratigraphic horizons for the period AD 1260-2010 is 20.9 mm H2O. Positive (+13%) anomalies of snow accumulation were found for AD 1661-1815 and AD 1992-2010, and negative (-12%) for AD 1260-1601. We hypothesized that the changes in snow accumulation are associated with regional peculiarities in atmospheric transport.

  3. High-resolution retinal imaging through open-loop adaptive optics

    NASA Astrophysics Data System (ADS)

    Li, Chao; Xia, Mingliang; Li, Dayu; Mu, Quanquan; Xuan, Li

    2010-07-01

    Using the liquid crystal spatial light modulator (LC-SLM) as the wavefront corrector, an open-loop adaptive optics (AO) system for fundus imaging in vivo is constructed. Compared with the LC-SLM closed-loop AO system, the light energy efficiency is increased by a factor of 2, which is helpful for the safety of fundus illumination in vivo. In our experiment, the subjective accommodation method is used to precorrect the defocus aberration, and three subjects with different myopia 0, -3, and -5 D are tested. Although the residual wavefront error after correction cannot to detected, the fundus images adequately demonstrate that the imaging system reaches the resolution of a single photoreceptor cell through the open-loop correction. Without dilating and cyclopleging the eye, the continuous imaging for 8 s is recorded for one of the subjects.

  4. 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

  5. Verlorenvlei - The first continuous Holocene high-resolution lake sediment record from the Winter Rainfall Zone of South Africa

    NASA Astrophysics Data System (ADS)

    Haberzettl, T.; Kasper, T.; Lederer, M.; Wündsch, M.; Frenzel, P.; Zabel, M.; Kirsten, K. L.; Meadows, M. E.; Quick, L. J.; St-Onge, G.; Maeusbacher, R.

    2015-12-01

    Verlorenvlei is a coastal lake in the Winter Rainfall Zone of the Western Cape Province of South Africa. Up to now several attempts have been made to recover sediment cores from this lake. However, no continuous high-resolution record covering large parts of the Holocene has been available so far. Within the project RAIN (Regional Archives for Integrated iNvestigations) it was possible to recover a 14.2 m paired parallel core from the central part of Verlorenvlei. Investigations on recent surface sediment distributions (elemental composition and grain sizes) indicate that this sediment core is very well suited for paleoenvironmental reconstructions. Using a set of 23 radiocarbon ages, a chronology for the past 9,000 cal BP was established which suggests continuous sedimentation over this period. Preliminary lithological and geochemical investigations show that this record can be used for sea level reconstructions as the lake was periodically inundated by the ocean during the past 9,000 cal BP. This is recorded in distinctly elevated Ca and Sr contents as well as the occurrence of marine indicator species (snail and mussel shells) in parts of the sediment core. Thin, pale grey layers of fine sediment occurring at various sediment depths seem to reflect event related deposits. In terms of lithology, geochemical and magnetic composition, the upper 50 cm clearly differ from the rest of the record and indicate increased sediment supply from the catchment, which is likely linked to anthropogenic farming activities. In conclusion, the newly recovered sediment record from Verlorenvlei offers excellent potential for a detailed, high-resolution reconstruction of sea level changes, climate variations and anthropogenic impact during the past 9,000 cal BP in an area in which natural archives are very scarce or poorly dated.

  6. Recording high-resolution images of two-dimensional crystals of membrane proteins.

    PubMed

    Avila-Sakar, Agustin; Li, Xueming; Zheng, Shawn Q; Cheng, Yifan

    2013-01-01

    Principles underlying the recording of high-quality/resolution images of two-dimensional crystals of membrane proteins are discussed in the context of instrumental conditions and operational procedures. A detailed example of low-dose microscope settings is provided along with an overview of a program that implements a computer-aided data acquisition procedure.

  7. Continuous zooming optical design with a high-resolution and large-zoom ratios used for precision strike TV camera

    NASA Astrophysics Data System (ADS)

    Wang, Ling; Chang, Weijun; Qiang, Hua; Zhang, Bo

    2015-02-01

    According to the requirement of detector, a continuous zooming TV camera with a high resolution and a large zoom ratios used for precision strike was designed. In this paper, basis the selection of continuous zooming optical systems was discussed. Combing with PW method, the incipient structure was computed. Using the CODE V, the optimum design was done. Having analyzed the cam curve of this zooming system, a continuous zooming optical system meeting the technical requirements well was designed, which provided the technical support for the miniaturization of the structure and the stability of the optic axis. This continuous zooming optical system has been checked with image quality testing, real imaging and environment testing and the result showed that the image quality was well, the optic axis was stable and the system meet the requirement of detector well.

  8. A high-resolution geochemical record of Late Quaternary paleohydrological conditions from Chihuahuan Desert, Mexico

    NASA Astrophysics Data System (ADS)

    Quiroz-Jiménez, J.; Roy, P.

    2013-05-01

    Paleolake Babicora is located at 29°N in the northern Mexico and sediments deposited in the basin provide useful information about the late Quaternary paleohydrological conditions of Chihuahuan Desert. The proxy-records of productivity, pluvial discharge into the basin, lake water salinity and aeolian activity in surroundings of the basin over the last 80 cal ka BP were reconstructed by analyzing the concentrations of total organic carbon, carbonates, C/N, Ti, Sr and Zr/Al in a 976 cm long sediment core. During 80-58 cal ka BP, the pluvial discharge was higher and the water column was characterized by lower salinity (wet conditions). Terrestrial vegetation had higher influence on the organic carbon deposited between 71 and 53 cal ka BP. We record paleohydrological instability with millennial-scale fluctuations in the last 40 cal ka BP. Arid conditions possibly reached its maximum at ca. 40 cal ka BP, characterized with a hiatus in sedimentation related to aeolian activity. Comparison between the paleohydrological record from Babicora and variability of winter precipitation from southwest USA suggest that the runoff into Babicora was controlled by summer season precipitation. The periods of more pluvial discharge were contemporary to the north Atlantic interstadials and vice versa.

  9. High-resolution mineral dust and sea ice proxy records from the Talos Dome ice core

    NASA Astrophysics Data System (ADS)

    Schüpbach, S.; Federer, U.; Kaufmann, P. R.; Albani, S.; Barbante, C.; Stocker, T. F.; Fischer, H.

    2013-12-01

    In this study we report on new non-sea salt calcium (nssCa2+, mineral dust proxy) and sea salt sodium (ssNa+, sea ice proxy) records along the East Antarctic Talos Dome deep ice core in centennial resolution reaching back 150 thousand years (ka) before present. During glacial conditions nssCa2+ fluxes in Talos Dome are strongly related to temperature as has been observed before in other deep Antarctic ice core records, and has been associated with synchronous changes in the main source region (southern South America) during climate variations in the last glacial. However, during warmer climate conditions Talos Dome mineral dust input is clearly elevated compared to other records mainly due to the contribution of additional local dust sources in the Ross Sea area. Based on a simple transport model, we compare nssCa2+ fluxes of different East Antarctic ice cores. From this multi-site comparison we conclude that changes in transport efficiency or atmospheric lifetime of dust particles do have a minor effect compared to source strength changes on the large-scale concentration changes observed in Antarctic ice cores during climate variations of the past 150 ka. Our transport model applied on ice core data is further validated by climate model data. The availability of multiple East Antarctic nssCa2+ records also allows for a revision of a former estimate on the atmospheric CO2 sensitivity to reduced dust induced iron fertilisation in the Southern Ocean during the transition from the Last Glacial Maximum to the Holocene (T1). While a former estimate based on the EPICA Dome C (EDC) record only suggested 20 ppm, we find that reduced dust induced iron fertilisation in the Southern Ocean may be responsible for up to 40 ppm of the total atmospheric CO2 increase during T1. During the last interglacial, ssNa+ levels of EDC and EPICA Dronning Maud Land (EDML) are only half of the Holocene levels, in line with higher temperatures during that period, indicating much reduced sea

  10. Phase-distortion correction based on stochastic parallel proportional-integral-derivative algorithm for high-resolution adaptive optics

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Wu, Ke-nan; Gao, Hong; Jin, Yu-qi

    2015-02-01

    A novel optimization method, stochastic parallel proportional-integral-derivative (SPPID) algorithm, is proposed for high-resolution phase-distortion correction in wave-front sensorless adaptive optics (WSAO). To enhance the global search and self-adaptation of stochastic parallel gradient descent (SPGD) algorithm, residual error and its temporal integration of performance metric are added in to incremental control signal's calculation. On the basis of the maximum fitting rate between real wave-front and corrector, a goal value of metric is set as the reference. The residual error of the metric relative to reference is transformed into proportional and integration terms to produce adaptive step size updating law of SPGD algorithm. The adaptation of step size leads blind optimization to desired goal and helps escape from local extrema. Different from conventional proportional-integral -derivative (PID) algorithm, SPPID algorithm designs incremental control signal as PI-by-D for adaptive adjustment of control law in SPGD algorithm. Experiments of high-resolution phase-distortion correction in "frozen" turbulences based on influence function coefficients optimization were carried out respectively using 128-by-128 typed spatial light modulators, photo detector and control computer. Results revealed the presented algorithm offered better performance in both cases. The step size update based on residual error and its temporal integration was justified to resolve severe local lock-in problem of SPGD algorithm used in high -resolution adaptive optics.

  11. High-resolution patterning electronic polymers using dopant induced solubility control (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Moule, Adam J.; Jacobs, Ian E.; Li, Jun; Burg, Stephanie L.; Bilsky, David J.; Rotondo, Brandon T.; Stroeve, Pieter

    2015-08-01

    Organic electronics promise to provide flexible, large-area circuitry such as photovoltaics, displays, and light emitting diodes that can be fabricated inexpensively from solutions. A major obstacle to this vision is that most conjugated organic materials are miscible, making solution-based fabrication of multilayer or micro- to nanoscale patterned films problematic. Here we demonstrate that the solubility of prototypical conductive polymer poly(3-hexylthiophene) (P3HT) can be reversibly "switched off" using high electron affinity molecular dopants, then later recovered with light or a suitable dedoping solution. Using this technique, we are able to stack mutually soluble materials and laterally pattern polymer films using evaporation of dopants through a shadow mask or with light, achieving sub-micrometer, optically limited feature sizes. After forming these structures, the films can be dedoped without disrupting the patterned features; dedoped films have identical optical characteristics, charge carrier mobilities, and NMR spectra as as-cast P3HT films. This method greatly simplifies solution-based device fabrication, is easily adaptable to current manufacturing workflows, and is potentially generalizable to other classes of materials.

  12. Ultrasensitive high resolution laser spectroscopy and its application to optical frequency standards

    NASA Astrophysics Data System (ADS)

    Ye, Jun

    1997-09-01

    Advanced laser stabilization techniques now enable one to lock laser frequencies onto line centers of natural atomic/molecular resonances with unprecedented precision and accuracy. In this dissertation we discuss our effort in utilizing these techniques to establish visible optical frequency standards. By summarizing our earlier results on frequency measurements of the 87Rb D2 line at 780 nm 127I2 hyperfine transitions at 532 nm, we show the advantage of using a higher quality reference line, usually characterized by its narrower linewidth, higher attainable signal-to-noise ratio and lower sensitivity toward external perturbations. We then present a novel approach of cavity-enhanced frequency modulation spectroscopy for ultra-sensitive detections. The powerful utility of this new technique in the field of frequency standards is demonstrated by probing saturated molecular overtone transitions in the visible and near infrared. Weakly-absorbing gases such as C2H2 and C2HD are placed inside an external high-finesse resonator to enhance their detection sensitivities. A frequency modulation technique is employed to achieve a shot noise limited signal-to- noise ratio. The rf modulation frequency is chosen to match the cavity's free spectral range in order to avoid the cavity-induced conversion of laser frequency noise into amplitude noise. The molecular saturated dispersion signal is directly recovered after demodulation of the cavity transmitted light. A record high integrated absorption sensitivity of 5× 10-13/ (1× 10-14/cm) (at 1 second averaging time) has been obtained. Systematic studies on this new technique are presented on topics of detection sensitivity, signal line shape, signal size and slope, and pressure dependent linewidth broadening and linecenter shift. A Nd:YAG laser is stabilized on the P(5) transition in the (ν2+3/ ν3) overtone band of C2HD at 1.064 μm. Its absolute frequency is established. The excellent signal- to-noise ratio produces a frequency

  13. Note: Autocollimation with ultra-high resolution and stability using telephoto objective together with optical enlargement and beam drift compensation

    NASA Astrophysics Data System (ADS)

    Zhu, Fan; Tan, Xinran; Tan, Jiubin; Fan, Zhigang

    2016-08-01

    An autocollimation (AC) setup with ultra-high resolution and stability for micro-angle measurement is presented. The telephoto objective, which is characterized in long focal length at a compact structure size, and the optical enlargement unit, which can magnify the image displacement to improve its measurement resolution and accuracy, are used to obtain an ultra-high measurement resolution of the AC. The common-path beam drift compensation is used to suppress the drift of measurement results, which is evident in the high-resolution AC, thus to obtain a high measurement stability. Experimental results indicate that an effective resolution of better than 0.0005 arc sec (2.42 nrad) over a measurement range of ±30 arc sec and a 2-h stability of 0.0061 arc sec (29.57 nrad) can be achieved.

  14. Note: Autocollimation with ultra-high resolution and stability using telephoto objective together with optical enlargement and beam drift compensation.

    PubMed

    Zhu, Fan; Tan, Xinran; Tan, Jiubin; Fan, Zhigang

    2016-08-01

    An autocollimation (AC) setup with ultra-high resolution and stability for micro-angle measurement is presented. The telephoto objective, which is characterized in long focal length at a compact structure size, and the optical enlargement unit, which can magnify the image displacement to improve its measurement resolution and accuracy, are used to obtain an ultra-high measurement resolution of the AC. The common-path beam drift compensation is used to suppress the drift of measurement results, which is evident in the high-resolution AC, thus to obtain a high measurement stability. Experimental results indicate that an effective resolution of better than 0.0005 arc sec (2.42 nrad) over a measurement range of ±30 arc sec and a 2-h stability of 0.0061 arc sec (29.57 nrad) can be achieved. PMID:27587181

  15. Three-dimensional imaging of eye surface pathologies and contact lens fit with high resolution spectral optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wojtkowski, M.; Kałużny, B.; Szkulmowska, A.; Bajraszewski, T.; Szkulmowski, M.; Targowski, P.; Kowalczyk, A.

    2007-02-01

    Purpose: To show potential of Spectral Optical Coherence Tomography system for high resolution, cross-sectional and three-dimensional imaging of eye surface pathologies. Methods: High-speed spectral OCT prototype instrument with 4.5 μm axial resolution was designed and constructed for clinical use. Measurements of anterior segment of human eye have been performed in ophthalmology clinic on 86 patients suffering various eye surface disorders including corneal dystrophies, corneal scars, conjunctival folds, keratoconus, bullus keratopathy, filtration blebs and other post-operative changes. Additionally, examinations of contact lens fit on 97 healthy corneas have been performed up to date. Results: High quality, high resolution cross-sectional images and three-dimensional reconstructions of cornea, conjunctiva and sclera of pathologic eyes together with examples of numerical analysis including segmentation of fluid in filtration blebs, scars and deposits are shown. Quantitative analysis of contact lens fit is demonstrated.

  16. A Combined Multiple-SLED Broadband Light Source at 1300 nm for High Resolution Optical Coherence Tomography

    PubMed Central

    Wang, Hui; Jenkins, Michael W.; Rollins, Andrew M.

    2013-01-01

    We demonstrate a compact, inexpensive, and reliable fiber–coupled light source with broad bandwidth and sufficient power at 1300 nm for high resolution optical coherence tomography (OCT) imaging in real-time applications. By combining four superluminescent diodes (SLEDs) with different central wavelengths, the light source has a bandwidth of 145 nm centered at 1325 nm with over 10 mW of power. OCT images of an excised stage 30 embryonic chick heart acquired with our combined SLED light source (<5 μm axial resolution in tissue) are compared with images obtained with a single SLED source (~10 μm axial resolution in tissue). The high resolution OCT system with the combined SLED light source provides better image quality (smaller speckle noise) and a greater ability to observe fine structures in the embryonic heart. PMID:24347689

  17. A Combined Multiple-SLED Broadband Light Source at 1300 nm for High Resolution Optical Coherence Tomography.

    PubMed

    Wang, Hui; Jenkins, Michael W; Rollins, Andrew M

    2008-04-01

    We demonstrate a compact, inexpensive, and reliable fiber-coupled light source with broad bandwidth and sufficient power at 1300 nm for high resolution optical coherence tomography (OCT) imaging in real-time applications. By combining four superluminescent diodes (SLEDs) with different central wavelengths, the light source has a bandwidth of 145 nm centered at 1325 nm with over 10 mW of power. OCT images of an excised stage 30 embryonic chick heart acquired with our combined SLED light source (<5 μm axial resolution in tissue) are compared with images obtained with a single SLED source (~10 μm axial resolution in tissue). The high resolution OCT system with the combined SLED light source provides better image quality (smaller speckle noise) and a greater ability to observe fine structures in the embryonic heart.

  18. Fabrication of high-resolution reflective scale grating for an optical encoder using a patterned self-assembly process

    NASA Astrophysics Data System (ADS)

    Fan, Shanjin; Jiang, Weitao; Li, Xuan; Yu, Haoyu; Lei, Biao; Shi, Yongsheng; Yin, Lei; Chen, Bangdao; Liu, Hongzhong

    2016-07-01

    Steel tape scale grating of a reflective incremental linear encoder has a key impact on the measurement accuracy of the optical encoder. However, it is difficult for conventional manufacturing processes to fabricate scale grating with high-resolution grating strips, due to process and material problems. In this paper, self-assembly technology was employed to fabricate high-resolution steel tape scale grating for a reflective incremental linear encoder. Graphene oxide nanoparticles were adopted to form anti-reflective grating strips of steel tape scale grating. They were deposited in the tape, which had a hydrophobic and hydrophilic grating pattern when the dispersion of the nanoparticles evaporated. A standard lift-off process was employed to fabricate the hydrophobic grating strips on the steel tape. Simultaneously, the steel tape itself presents a hydrophilic property. The hydrophobic and hydrophilic grating pattern was thus obtained. In this study, octafluorocyclobutane was used to prepare the hydrophobic grating strips, due to its hydrophobic property. High-resolution graphene oxide steel tape scale grating with a pitch of 20 μm was obtained through the self-assembly process. The photoelectric signals of the optical encoder containing the graphene oxide scale grating and conventional scale grating were tested under the same conditions. Comparison test results showed that the graphene oxide scale grating has a better performance in its amplitude and harmonic components than that of the conventional steel tape scale. A comparison experiment of position errors was also conducted, demonstrating an improvement in the positioning error of the graphene oxide scale grating. The comparison results demonstrated the applicability of the proposed self-assembly process to fabricate high-resolution graphene oxide scale grating for a reflective incremental linear encoder.

  19. Late Permian-earliest Triassic high-resolution organic carbon isotope and palynofacies records from Kap Stosch (East Greenland)

    NASA Astrophysics Data System (ADS)

    Sanson-Barrera, Anna; Hochuli, Peter A.; Bucher, Hugo; Schneebeli-Hermann, Elke; Weissert, Helmut; Adatte, Thierry; Bernasconi, Stefano M.

    2015-10-01

    During and after the end Permian mass extinction terrestrial and marine biota underwent major changes and reorganizations. The latest Permian and earliest Triassic is also characterized by major negative carbon isotope shifts reflecting fundamental changes in the carbon cycle. The present study documents a high-resolution bulk organic carbon isotope record and palynofacies analysis spanning the latest Permian-earliest Triassic of East Greenland. An almost 700 meter thick composite section from Kap Stosch allowed discriminating 6 chemostratigraphic intervals that provide the basis for the correlation with other coeval records across the world, and for the recognition of basin wide transgressive-regressive events documenting tectonic activity during the opening of the Greenland-Norway Basin. The identification of the main factors that influenced the organic carbon isotope signal during the earliest Triassic (Griesbachian to Dienerian) was possible due to the combination of bulk organic carbon isotope, palynofacies and Rock-Eval data. Two negative carbon isotopic shifts in the Kap Stosch record can be correlated with negative shifts recorded in coeval sections across the globe. A first negative shift precedes the base of the Triassic as defined by the first occurrence of the conodont Hindeodus parvus in the Meishan reference section, and the second one coincides with the suggested Griesbachian-Dienerian boundary. This new organic carbon isotope record from the extended Kap Stosch section from the Boreal Realm documents regional and global carbon cycle signals of the interval between the latest Palaeozoic and the onset of the Mesozoic.

  20. High resolution in-vivo imaging of skin with full field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Dalimier, E.; Bruhat, Alexis; Grieve, K.; Harms, F.; Martins, F.; Boccara, C.

    2014-03-01

    Full-field OCT (FFOCT) has the ability to provide en-face images with a very good axial sectioning as well as a very high transverse resolution (about 1 microns in all directions). Therefore it offers the possibility to visualize biological tissues with very high resolution both on the axial native view, and on vertical reconstructed sections. Here we investigated the potential dermatological applications of in-vivo skin imaging with FFOCT. A commercial FFOCT device was adapted for the in-vivo acquisition of stacks of images on the arm, hand and finger. Several subjects of different benign and pathological skin conditions were tested. The images allowed measurement of the stratum corneum and epidermis thicknesses, measurement of the stratum corneum refractive index, size measurement and count of the keratinocytes, visualization of the dermal-epidermal junction, and visualization of the melanin granules and of the melanocytes. Skins with different pigmentations could be discriminated and skin pathologies such as eczema could be identified. The very high resolution offered by FFOCT both on axial native images and vertical reconstructed sections allows for the visualization and measurement of a set of parameters useful for cosmetology and dermatology. In particular, FFOCT is a potential tool for the understanding and monitoring of skin hydration and pigmentation, as well as skin inflammation.

  1. A high-resolution angiosperm pollen reference record covering Albian mid-latitude coastal deposits (Lusitanian Basin, Portugal)

    NASA Astrophysics Data System (ADS)

    Horikx, Maurits; Dinis, Jorge L.; Heimhofer, Ulrich

    2013-04-01

    The Lusitanian Basin in Portugal is one of the most important areas to investigate the rise and radiation of early angiosperms. Here, important micro-, macro- and mesofossil remains including pollen, reproductive organs, fruits and seeds have been found. In this study, a high-resolution Early to Late Albian pollen record from a thick (~160m) coastal succession in the Lusitanian Basin containing mixed carbonate-siliciclastic near-shore deposits is generated. The outcrop is located near the town of Ericeira (São Julião) and exhibits some important new features compared to existing records from the Lusitanian basin. The comparatively proximal depositional setting and high sedimentation rate of the São Julião outcrop is well suited for high-resolution palynological sampling compared to previously studied, more distal outcrops. In addition, the succession covers almost the entire Albian including a thick interval representing Late Albian strata. Dating of the succession was obtained using dinoflagellate cyst biostratigraphy, bulk C-isotope analysis and strontium isotope analysis of low-Mg oysters and rudist shells. The high-resolution pollen record shows a distinct radiation pattern of early angiosperm pollen as well as significant changes in the accompanying palynoflora. During most of the section gymnosperm pollen types such as Classopollis spp., Inaperturopollenites spp. and Exesipollenites spp. are dominant. Angiosperm pollen abundances do not exceed 20%, although angiosperms increase slightly from the Early Albian onwards. Monoaperturate grains of magnoliid or monocot affinity remain the most dominant angiosperm pollen type, both in abundances and diversity. Tricolpate and zonoaperturate pollen grains are also present. In addition, the occurrence of several odd-shaped Dichastopollenites-type pollen types is intriguing. The palynological results indicate a warm and dry climate during most of the Albian, although a rise in the spores over pollen ratio in the

  2. Late Holocene climatic changes in west Africa, a high resolution diatom record from equatorial Cameroon

    NASA Astrophysics Data System (ADS)

    Nguetsop, Victor François; Servant-Vildary, Simone; Servant, Michel

    2004-03-01

    Holocene climatic changes in West Africa are usually explained by increased/decreased activity of the monsoon from the Guinean Gulf toward the continent. According to a diatom record from Lake Ossa (3°50'N, 9°36'E), we suggest that, in the near coastal areas of Cameroon, phases of intensification of the monsoon were marked by reduced precipitation and reduced evaporation, conditions nowadays prevailing South of the equator (4-5°S) during the austral winter. Lake Ossa is a shallow lake located in one of the rainiest area of the African rain forest belt. During the wet season (March-November) it is fed by acid meteoric waters entailing low pH in the lacustrine waters. During the dry season (December-February) groundwater discharges allow the persistence of acid waters near the borders of the lake, but, in the inner parts, the waters tend to be alkaline, alkaliphilous diatoms are abundant in the surface sediment samples and are used as indicators of low precipitation. At that time, atmospheric dust containing reworked diatoms from Saharan Quaternary deposits is transported by the northern trade winds and reaches the Ossa area. Wind blown diatoms are considered as a signature of the northern trade winds. A diatom record from the western deep part of Lake Ossa has provided climatic data for the mid-late Holocene at a resolution of 50-60 years. A major climatic change at 2700 cal yr BP was marked by the appearance of wind blown diatoms. A millennial-scale alternation between low and high precipitation episodes is recorded during the last 5500 years. The low precipitation episodes before 2700 cal yr BP are interpreted as a consequence of a northward extension of the climatic conditions that nowadays characterize the Southern Congo during the austral winter, when the monsoon extends into West Africa and reaches the northern sub-tropical latitudes. The effects of low precipitation on the water balance and on the rain forest were obliterated by an extremely low

  3. A High-Resolution Carbonate Record from Holocene IMAGES core MD992286, Skagerrak

    NASA Astrophysics Data System (ADS)

    Gyllencreutz, R.

    2003-04-01

    Marine sediments in the 32.4 m long piston core MD99-2286, provides a continuous and detailed palaeoceanographic and palaeoenvironmenatal record of the last 12 000 years in the Skagerrak. The investigated area is characterised by high sedimentation rates and intense water mass mixing, as a branch of the North Atlantic Current turns anti-clockwise, slows down and becomes mixed with other waters to form the Norwegian Coastal Current. Present-day SSTs in Skagerrak are strongly linked to the NAO-index. Carbonate content in core MD99-2286 was measured using coulometry with 5-cm resolution. The carbonate record shows a steep rise from 9 to 15 % carbonate from 10 ka to 8 ka, and then a gradual decreasing trend down to about 12 % around 4 500 cal y BP. The timing of the peak at 8 ka coincides with the opening of the English Channel. The most likely processes controlling carbonate content in the Skagerrak sediments are redeposition of older carbonate particles (mainly controlled by the Jutland Current) and primary productivity competing with dilution by terrigenous material. The carbonate record from MD99-2286 correlates with a palaeotemperature reconstruction based on oxygen isotopes from a speleothem in northern Norway. The correlation is positive in the interval 9 ka to about 5 ka, and negative from 5 ka to present. The timing of the shift in correlation matches the establishment of the modern circulation pattern, which is marked by a hydrographic shift at 5.5 ka, interpreted from grain size and biostratigraphical data in a core from Skagen. This shift is manifested by an increase in the Jutland Current and stronger inflow of saline North Sea water to Skagerrak and Kattegat. The CALYPSO-corer used for core MD99-2286 is believed to disturb the topmost sediments in cores. Therefore, a 2.5 m long gravity core, Sk000209-2, was retrieved from a nearby location in order to get full recovery of the surface sediments. Age control in core MD99-2286 is obtained from 20 AMS C-14

  4. Late Holocene High Resolution Multi-Proxy Climate and Environmental Records From Lake Van, Eastern Turkey

    NASA Astrophysics Data System (ADS)

    Barlas Simsek, F.; Cagatay, M. N.

    2012-04-01

    Lake Van is the world's largest soda Lake with a surface area of 3522 km2, a water volume of 576 km3 and a maximum water depth of 451m. It is situated in the East Anatolian Highlands of Turkey at (43°E and 38.5°N) at an altitude of 1650m. The lake is characterized by a high pH (~9.8) and annually varved sediments. Four interface cores with lengths of up to 1.4 m and undisturbed top were collected from Lake Van. All cores were analyzed for physical properties using Geotek Multi Sensor Core Logger (MSCL), inorganic elemental analysis using an Itrax XRF core scanner, and total organic carbon (TOC) and inorganic carbon (TIC) analysis using TOC analyzer. Radionuclide (210Pb and 137Cs) analysis and varv-counting were used to establish the chronology, with the two methods providing very conformable results. The varves were counted using 60 µm resolution digital X-ray radiograpic images. An increase in the activity of 137Cs radioisotope in comparison with 210Pb age data gives support for the presence of the record of 1986 Chernobyl nuclear accident. The sedimentation rate varies from 0.4 to 0.7 mm/year at different core sites. Our sedimentary records extend back to about 3600 a BP and are correlatable between the different core sites. Elemental (Ti, Fe, K) and magnetic susceptibility profiles suggest relatively large detrital input occurred over the last 750 a BP, during 1700-1150 a BP, 2150-1700 a BP, 2150-1800 a BP, 2450-2350 a BP, and 3150-2600 a BP, which are interpereted to correspond to wet periods. The intervening periods during 1150-750 a BP, 1800-1700 a BP, and 2350-2150 a BP, 2600-2450 a BP are characterized by low detrital input and high carbonate contents, correponding to relatively dry periods. There also short dry periods at 150 a, BP, 1450-1400 a BP and 2950 a BP within the long wet periods listed above. High organic productivity correponding to >5% TOC in the sediments occurs during 110 a BP, 210 a BP, 460 a BP, 530 a BP, 790 a BP, 1460 a BP, and 1940 a

  5. A high resolution record of chlorine-36 nuclear-weapons-tests fallout from Central Asia

    USGS Publications Warehouse

    Green, J.R.; Cecil, L.D.; Synal, H.-A.; Santos, J.; Kreutz, K.J.; Wake, C.P.

    2004-01-01

    The Inilchek Glacier, located in the Tien Shan Mountains, central Asia, is unique among mid-latitude glaciers because of its relatively large average annual accumulation. In July 2000, two ice cores of 162 and 167 meters (m) in length were collected from the Inilchek Glacier for (chlorine-36) 36Cl analysis a part of a collaborative international effort to study the environmental changes archived in mid-latitude glaciers worldwide. The average annual precipitation at the collection site was calculated to be 1.6 m. In contrast, the reported average annual accumulations at the high-latitude Dye-3 glacial site, Greenland, the mid-latitude Guliya Ice Cap, China, and the mid-latitude Upper Fremont Glacier, Wyoming, USA, were 0.52, 0.16 and 0.76 m, respectively. The resolution of the 36Cl record in one of the Inilchek ice cores was from 2 to 10 times higher than the resolution of the records at these other sites and could provide an opportunity for detailed study of environmental changes that have occurred over the past 150 years. Despite the differences in accumulation among these various glacial sites, the 36Cl profile and peak concentrations for the Inilchek ice core were remarkably similar in shape and magnitude to those for ice cores from these other sites. The 36Cl peak concentration from 1958, the year during the mid-1900s nuclear-weapons-tests period when 36Cl fallout was largest, was preserved in the Inilchek core at a depth of 90.56 m below the surface of the glacier (74.14-m-depth water equivalent) at a concentration of 7.7 ?? 105 atoms of 36Cl/gram (g) of ice. Peak 36Cl concentrations from Dye-3, Guliya and the Upper Fremont glacial sites were 7.1 ?? 105, 5.4 ?? 105 and 0.7 ?? 105 atoms of 36Cl/g of ice, respectively. Measurements of 36Cl preserved in ice cores improve estimates of historical worldwide atmospheric deposition of this isotope and allow the sources of 36Cl in ground water to be better identified. ?? 2004 Published by Elsevier B.V.

  6. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records.

    PubMed

    Martínez-Botí, M A; Foster, G L; Chalk, T B; Rohling, E J; Sexton, P F; Lunt, D J; Pancost, R D; Badger, M P S; Schmidt, D N

    2015-02-01

    Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2.

  7. Chemical characterization of Lake Constance sediments record by high resolution EDXRF

    NASA Astrophysics Data System (ADS)

    Rammlmair, D.; Wessels, M.

    2003-04-01

    Sediment-input into Lake Constance is mainly characterized by the Alpine Rhine River which drains some 12000 km2 in the Alps. Due to melting of snow in the catchment, the annual runoff and sediment input has a strong maximum in summer. This is superimposed by single events of heavy rain fall generating strong flood events and leads to annually laminated sediments along the northern slope of Lake Constance. These were used to reconstruct past environmental history and processes within the lake and its catchment, such as heavy metal contamination, eutrophication, and climate history. A typical core covering a time span of some 180 years during which the Lake and its catchment was heavily influenced by hydraulic engineering (end of 1800s), chemical pollution, and eutrophication and recovery since the 1990s was scanned for major and trace element contents with an EDXRF core scanner (Mo-tube, 45 kV, 30mA, slit capillary, 50 µm step size and 30 sec signal accumulation time). In our contribution, we present first results of selected elements which were used to characterize the sedimentary record according to - background-sediments deposited during years with low runoff and low allochthonous sediment accumulation influenced by anthropogenic heavy metal input (brownish-grey layers) - calcite precipitation within the lake (thin white layers) - individual flood-layers of tributaries to the Alpine-Rhine-River System (grey lamina) - other smaller tributaries draining the molasse catchment (brown and yellowish layers) - chemical gradation within a single layer.

  8. Plio-Pleistocene climate sensitivity evaluated using high-resolution CO2 records.

    PubMed

    Martínez-Botí, M A; Foster, G L; Chalk, T B; Rohling, E J; Sexton, P F; Lunt, D J; Pancost, R D; Badger, M P S; Schmidt, D N

    2015-02-01

    Theory and climate modelling suggest that the sensitivity of Earth's climate to changes in radiative forcing could depend on the background climate. However, palaeoclimate data have thus far been insufficient to provide a conclusive test of this prediction. Here we present atmospheric carbon dioxide (CO2) reconstructions based on multi-site boron-isotope records from the late Pliocene epoch (3.3 to 2.3 million years ago). We find that Earth's climate sensitivity to CO2-based radiative forcing (Earth system sensitivity) was half as strong during the warm Pliocene as during the cold late Pleistocene epoch (0.8 to 0.01 million years ago). We attribute this difference to the radiative impacts of continental ice-volume changes (the ice-albedo feedback) during the late Pleistocene, because equilibrium climate sensitivity is identical for the two intervals when we account for such impacts using sea-level reconstructions. We conclude that, on a global scale, no unexpected climate feedbacks operated during the warm Pliocene, and that predictions of equilibrium climate sensitivity (excluding long-term ice-albedo feedbacks) for our Pliocene-like future (with CO2 levels up to maximum Pliocene levels of 450 parts per million) are well described by the currently accepted range of an increase of 1.5 K to 4.5 K per doubling of CO2. PMID:25652996

  9. How well do testate amoebae transfer functions relate to high-resolution water-table records?

    NASA Astrophysics Data System (ADS)

    Holden, Joseph; Swindles, Graeme; Raby, Cassandra; Blundell, Antony

    2014-05-01

    Testate amoebae (TA) community composition records from peat cores are often used to infer past water-table conditions on peatland sites. However, one of the problems is that validation of water-table depths used in such work typically comes from a one-off water-table measurement or a few measurements of water-table depth from the testate amoebae sample extraction point. Furthermore, one value of water-table depth is produced by the transfer function reconstruction, with sample-specific errors generated through a statistical resampling approach. However, we know that water tables fluctuate in peatlands and are dynamic. Traditional TA water-table data may not adequately capture a mean value from a site, and may not account for water-table dynamics (e.g. seasonal or annual variability) that could influence the TA community composition. We analysed automatically logged (at least hourly, mainly 15-min) peatland water-table data from 72 different dipwells located across northern Sweden, Wales and the Pennine region of England. Each location had not been subject to recent management intervention. A suite of characteristics of water-table dynamics for each point were determined. At each point surface samples were extracted and the TA community composition was determined. Our results show that estimated water-table depth based on the TA community transfer functions poorly represents the real mean or median water tables for the study sites. The TA approach does, however, generally identify sites that have water tables that are closer to the surface for a greater proportion of the year compared to sites with deeper water tables for large proportions of the year. However, the traditional TA approach does not differentiate between sites with similar mean (or median) water-table depths yet which have quite different water table variability (e.g. interquartile range). We suggest some ways of improving water-table metrics for use in Holocene peatland hydrology reconstructions.

  10. A high resolution coccolithophore record of interglacial surface water variability from the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Schwab, Christian; Kinkel, Hanno; Weinelt, Mara; Repschläger, Janne; Blanz, Thomas

    2010-05-01

    The response of coccolithophores to changes in the Atlantic Meridional Overturning Circulation (AMOC) in the Azores Current system was investigated in detailed and well dated sediment cores from the Mid-Atlantic Ridge (MAR) southwest of the Azores Islands (38°N/31°W). The observed changes in the coccolith assemblage may be either caused by shifts in the position and/or strength of the Azores Current regime, as also evidenced in pronounced SST, SSS and nutrient inventory fluctuations. Two cores recovered from a small basin at the Mid-Atlantic Ridge (AMOCINT cruise MD 168, 2008), today situated underneath the transition zone between the oligotrophic Subtropical Gyre and the more productive North Atlantic Transitional Waters, provide early Holocene and deglacial sedimentation rates up to more than 70 cm/kyr. Today the site is characterized by relatively low surface productivity accordingly accumulation of biogenic material is only moderate. Substantial phytoplankton production takes place during early spring, when winter mixing relaxes and stratification sets in. An array of independent paleoproductivity proxies shows that productivity was considerably increased during cooler intervals (e.g.Younger Dryas) which enhanced the biogenic particle flux. This applies also to the short lived 8,2 kyr event as identified in the SST record. In general cold water species then (e.g. C. pelagicus, G. muellerae), today nearly absent from the site, occur significantly. Oppositely F. profunda, an indicator for low productivity, shows peak abundance during the late Holocene. The coccolith based paleoproductivity reconstructions are supported by geochemical proxies (e.g. XRF Ba/Ti and Si/Ca ratios) exhibiting pronounced peak maxima during cold fluctuations. Pronounced changes in the productivity and hydrographic regimes suggest that the Azores Current system is highly sensitive to AMOC variability. Changes in the Azores Current system appear to be precisely in phase with changes in

  11. A New Method of Obtaining High-Resolution Paleoclimate Records from Speleothem Fluid Inclusions

    NASA Astrophysics Data System (ADS)

    Logan, A. J.; Horton, T. W.

    2010-12-01

    a minimum quantity of ~100nL water was required. In contrast to liquid water analyses, carbonate inclusion waters gave highly variable results. As plenty of signal was produced from relatively small sample sizes (~20 mg), the observed isotopic variation most likely reflects fractionation during fluid extraction, or natural isotopic variability. Additional tests and modifications to the extraction procedure are in progress, using a recently collected New Zealand stalagmite from a West Coast cave (DOC collection permit WC-27462-GEO). U-Th age data will accompany a paleoclimate record from this stalagmite obtained using standard carbonate analytical techniques, and compared to the results from our new fluid inclusion analyses.

  12. A Novel Method to Retrieve Aerosol Optical Thickness from High-Resolution Optical Satellite Images for Air Quality Monitoring

    NASA Astrophysics Data System (ADS)

    Nield, J. M.; Wilson, R. T.; Milton, E. J.

    2015-12-01

    Aerosol Optical Thickness (AOT) data has many important applications including atmospheric correction of satellite imagery and monitoring of particulate matter air pollution. Current data products are generally available at a kilometre-scale resolution, but many applications require far higher resolutions. For example, particulate matter concentrations vary on a metre-scale, and thus data products at a similar scale are required to provide accurate assessments of particle densities and allow effective monitoring of air quality and analysis of local air quality effects on health. A novel method has been developed which retrieves per-pixel AOT values from high-resolution (~30m) satellite data. This method is designed to work over a wide range of land covers - including both bright and dark surfaces - and requires only standard visible and near-infrared data, making it applicable to a range of data from sensors such as Landsat, SPOT and Sentinel-2. The method is based upon an extension of the Haze Optimized Transform (HOT). The HOT was originally designed for assessing areas of thick haze in satellite imagery by calculating a 'haziness' value for each pixel in an image as the distance from a 'Clear Line' in feature space, defined by the high correlation between visible bands. Here, we adapt the HOT method and use it to provide AOT data instead. Significant extensions include Monte Carlo estimation of the 'Clear Line', object-based correction for land cover, and estimation of AOT from the haziness values through radiative transfer modelling. This novel method will enable many new applications of AOT data that were impossible with previously available low-resolution data, and has the potential to contribute significantly to our understanding of the air quality on health, the accuracy of satellite image atmospheric correction and the role of aerosols in the climate system.

  13. Retinal Structure of Birds of Prey Revealed by Ultra-High Resolution Spectral-Domain Optical Coherence Tomography

    PubMed Central

    Ruggeri, Marco; Major, James C.; McKeown, Craig; Knighton, Robert W.; Puliafito, Carmen A.

    2010-01-01

    Purpose. To reveal three-dimensional (3-D) information about the retinal structures of birds of prey in vivo. Methods. An ultra-high resolution spectral-domain optical coherence tomography (SD-OCT) system was built for in vivo imaging of retinas of birds of prey. The calibrated imaging depth and axial resolution of the system were 3.1 mm and 2.8 μm (in tissue), respectively. 3-D segmentation was performed for calculation of the retinal nerve fiber layer (RNFL) map. Results. High-resolution OCT images were obtained of the retinas of four species of birds of prey: two diurnal hawks (Buteo platypterus and Buteo brachyurus) and two nocturnal owls (Bubo virginianus and Strix varia). These images showed the detailed retinal anatomy, including the retinal layers and the structure of the deep and shallow foveae. The calculated thickness map showed the RNFL distribution. Traumatic injury to one bird's retina was also successfully imaged. Conclusions. Ultra-high resolution SD-OCT provides unprecedented high-quality 2-D and 3-D in vivo visualization of the retinal structures of birds of prey. SD-OCT is a powerful imaging tool for vision research in birds of prey. PMID:20554605

  14. Hypoxia in high-resolution sediment records: reconstructing the California Current Oxygen Minimum Zone on multi-decadal timescales

    NASA Astrophysics Data System (ADS)

    Moffitt, S. E.; Hill, T. M.

    2012-12-01

    The recent deglaciation event is an ideal laboratory to study the rapid expansion of Oxygen Minimum Zones (OMZs) and the ecological ramifications of such events. Santa Barbara Basin (SBB) sediments are high-resolution archives of seafloor ecosystems, recording both global-scale climate and regional-scale hydrographic events. Seafloor hypoxia in the California Current Ecosystem (CCE) is caused by OMZs in intermediate water depths (300-1200 m), and produces striking evidence in SBB sediment archives. We construct a vertical transect of proxies across SBB (34° 15'N, 119° 45'W) using a core from 418 m water depth (MV0811-15JC), and previously investigated cores from 440 m (MD02-2504) and 570 m (MD02-2503) water depths. Benthic foraminiferal assemblages and planktonic δ18O proxies were quantified at all three depths, while benthic invertebrate communities were quantified in the shallowest core at a 1-cm resolution (~10 years). This high-resolution invertebrate record provides a window into rapid, decadal-scale environmental change in continental margin ecosystems. Seafloor biodiversity is highly variable on 10-10^4 year timescales (across Protist, Mollusc, Arthropod and Echinoderm taxonomic groups), and is tightly coupled to both regional-scale environmental change and global-scale climate events. Additionally, we provide evidence that strongly hypoxic waters shoaled to <300 m water depth at Termination 1A (14.7 ka), implying that the upper boundary of the regional OMZ can expand >150 m on multi-decadal timescales. These data confirm that OMZs have rapidly expanded in the CCE during previous events of global-scale warming, and that continental margin seafloor biodiversity is variable on previously undescribed timescales.

  15. High-resolution CCD imagers using area-array CCD's for sensing spectral components of an optical line image

    NASA Technical Reports Server (NTRS)

    Elabd, Hammam (Inventor); Kosonocky, Walter F. (Inventor)

    1987-01-01

    CCD imagers with a novel replicated-line-imager architecture are abutted to form an extended line sensor. The sensor is preceded by optics having a slit aperture and having an optical beam splitter or astigmatic lens for projecting multiple line images through an optical color-discriminating stripe filter to the CCD imagers. A very high resolution camera suitable for use in a satellite, for example, is thus provided. The replicated-line architecture of the imager comprises an area-array CCD, successive rows of which are illuminated by replications of the same line segment, as transmitted by respective color filter stripes. The charge packets formed by accumulation of photoresponsive charge in the area-array CCD are read out row by row. Each successive row of charge packets is then converted from parallel to serial format in a CCD line register and its amplitude sensed to generate a line of output signal.

  16. 4He in Modern Cape Verde Corals: A High-Resolution Proxy Record of N. African Climate

    NASA Astrophysics Data System (ADS)

    Mukhopadhyay, S.; Kreycik, P.; Schrag, D. P.

    2005-12-01

    Mineral dust from arid and semi arid regions is an important component of climatic processes. The amount of dust emitted off continents is intimately linked with precipitation, which may itself be linked to atmospheric circulation driven by oceanic sea surface temperatures. Hence, reconstructing dust fluxes off continents with sub-decadal resolution can provide us with fundamental insights into feedbacks in the climate system. Unfortunately, such high-resolution dust flux records prior to the establishment of the Barbados dust sampling station are largely lacking. Here we show that 4He concentrations in annual bands in corals provides a high-resolution, reliable, and robust proxy record of dust flux from continents. Some traces phases in dust, such as zircons, are rich in U and Th and thus have extremely high concentrations of 4He. As some fraction of the dust settles out of the atmosphere and through the water column, corals incorporate the dust in their skeletons through filter feeding. Since the alpha stopping distance is greater than the particle size of wind blown dust, the mineral grains will not accumulate radiogenic helium after the dust is incorporated into the corals. We have measured the 4He concentration in annual bands dating back to 1960's in a modern coral that was collected in 1996 off the island of Sal, part of the Cape Verde archipelago. The coral is therefore, situated close to, and directly west of the dust source in the Sudano-Sahel region of the African continent. The 4He record from the coral shows remarkable similarity with the record from the Barbados dust sampling station. There is a continuous increase in 4He baseline values by a factor of two from the mid 1960's to the early 1990's as well as two pronounced peaks in the early 1970's and mid 1980's associated with severe drought in the Sudano-Sahel region. Our proxy record from the Cape Verde Island demonstrates that 4He concentrations in corals can be used reliably to reconstruct dust

  17. High-Resolution Dust record of last glacial period (MIS 4 to MIS 2) from Talos Dome Ice Core

    NASA Astrophysics Data System (ADS)

    Mazzola, Claudia; Maggi, Valter; Delmonte, Barbara; Marino, Federica; Albani, Samuel

    2010-05-01

    Mineral dust trapped in Antarctic ice cores plays an important role in the study of past climate and atmospheric circulation variability in the Southern Hemisphere. In this work we investigate the Talos Dome (Northern Victoria Land, East Antarctica) ice core dust concentration record through a Laser Sensor (LS) technique. Analyses were performed in continuous as a part of the Continuous Flow Analysis (CFA) system, and discontinuously with Beckman Coulter©Counter for comparison and LS calibration. The LS device provided two basic outputs: (1) "bag" (1 m long sections) mean values and (2) high resolution (1 cm resolution) data. Both signals were processed in the contest of this work and two dust records, respectively at low and high resolution, were produced. Here we report the bag mean dust record from the end of the last deglaciation (about 12,000 years B.P.) to Marine Isotopic Stage 4 (MIS 4, 70,000 years BP). The comparison of the TALDICE LS and EPICA-Dome C dust record provides interesting information about climatic conditions of South Pacific-Ross Sea sector of Antarctica, and atmospheric circulation patterns during last glacial period, with a good agreement between MIS 3 and Last Glacial Maximum (LGM), where several millennial and plurimillennial scale climatic oscillation are observed. For these reasons it is possible suppose that dust transport mechanisms towards TD and DC were the same during the last glacial period. However, MIS 4 in TD ice core was lower, both in concentration and flux, compared to EDC. Likely, during LGM, very cool air masses extended above the Antarctic plateau, even in TD area, have created a subsidence condition which haven't allowed the cyclonic perturbation to penetrate the interior of Antarctica continent. In fact, the Polar Front has moved towards lower latitude in that period, maintaining far away the disturbances. These preliminary observations suggest that the coupling between inner sites such as EDC and the Talos Dome

  18. High-resolution, dual-depth spectral-domain optical coherence tomography with interlaced detection for whole-eye imaging.

    PubMed

    Kim, Hyung-Jin; Kim, Pil Un; Hyeon, Min Gyu; Choi, Youngwoon; Kim, Jeehyun; Kim, Beop-Min

    2016-09-10

    Dual-depth spectral-domain optical coherence tomography (SD-OCT) enables high-resolution in vivo whole-eye imaging. Two orthogonally polarized beams from a source are focused simultaneously on two axial positions of the anterior segment and the retina. For the detector arm, a 1×2 ultrafast optical switch sequentially delivers two spectral interference signals to a single spectrometer, which extends the in-air axial depth range up to 9.44 mm. An off-pivot complex conjugate removal technique doubles the depth range for all anterior segment imaging. The graphics-processing-unit-based parallel signal processing algorithm supports fast two- and three-dimensional image displays. The obtained high-resolution anterior and retinal images are measured biometrically. The dual-depth SD-OCT system has an axial resolution of ∼6.4  μm in air, and the sensitivity is 91.79 dB at 150 μm from the zero-delay line. PMID:27661354

  19. High-resolution elemental records of Glycymeris glycymeris (Bivalvia) shells from the Iberian upwelling system: Ontogeny and environmental control

    NASA Astrophysics Data System (ADS)

    Freitas, Pedro; Richardson, Christopher; Chenery, Simon; Butler, Paul; Reynolds, David; Gaspar, Miguel; Scourse, James

    2015-04-01

    The great potential of bivalve shells as a high-resolution geochemical proxy archive of environmental conditions at the time of growth has been known for several decades. The elemental composition of bivalve shells has been studied with the purpose of reconstructing environmental conditions: e.g. seawater temperature (Sr and Mg), primary productivity (Li, Mn, Mo and Ba), redox conditions (Mn and Mo), terrigenous inputs (Li) and pollution (Cu, Zn, Cd and Pb). However, the interpretation of such records remains extremely challenging and complex, with processes affecting element incorporation in the shell (e.g. crystal fabrics, organic matrix, shell formation mechanisms and physiological processes) and the influence of more than one environmental parameter affecting elemental composition of bivalve shells. Nevertheless, bivalve shells remain an underused source of information on environmental conditions, with the potential to record high-resolution (sub-weekly to annually), multi-centennial time series of geochemical proxy data. The relatively long-lived bivalve (>100 years) Glycymeris glycymeris occurs in coastal shelf seas of Europe and North West Africa and is a valid annually resolved sclerochronological archive for palaeonvironmental reconstructions. The temporal framework provided by absolute annually dated shell material makes Glycymeris glycymeris a valuable, albeit unexplored, resource for investigating sub-annually resolved geochemical proxies. We present a first evaluation on the potential of Ba, P and U, the latter two elements rarely studied in bivalves, in Glycymeris glycymeris shells to record variations in the environmental conditions, respectively primary productivity, dissolved inorganic phosphorus and carbonate ion concentration/pH. High-resolution (31 to 77 samples per year) profiles of elemental/Ca ratios (E/Ca) over four years of growth (2001 to 2004) were obtained by LA-ICP-MS on two shells (13 and 16 years old) live-collected in 2010 at 30 m

  20. High-resolution record of Early to Middle Miocene climate variability from Site 1195, Marion Plateau, NE Queensland margin

    NASA Astrophysics Data System (ADS)

    Lowery, C.; Browning, E.; Leckie, R. M.; John, C. M.

    2012-12-01

    Constraining and quantifying eustatic variations has been a priority for stratigraphers since the publication of the first global sea level curves by the Exxon research group in the late 1970s. Quantifying the glacio-eustatic component of sea level signals has become a greater focus as more recent work has demonstrated that far-field effects like ice-sheet gravitation and isostasy imprint on the "true" eustatic signal of waxing and waning ice sheets so that coeval signals from disparate sites may show significantly different local sea level variations. To this end, the Miocene sediments on the Marion Plateau, a drowned carbonate platform on the Queensland margin of Australia, were drilled by ODP Leg 194 to provide an independent, southern hemisphere test of the sea level record of the New Jersey Margin of North America, the most complete and oft-cited record of Cenozoic sea level variability. A high-resolution record is critical to compare sea level variations across hemispheres. Natural Gamma Ray (NGR) logs of core holes can provide a complete, high-resolution record independent of any problems with core recovery or sampling interval. We here present a NGR record of ODP Site 1195 tied to recently completed nannofossil assemblage data, planktic/benthic foraminiferal ratios, sedimentary particle counts, and benthic foraminifera stable isotopes. Peaks in glauconite and clay content correspond to peaks in NGR. The largest of these peaks correspond to sequence boundaries (lowstands), as glauconite accumulates during periods of low sedimentation along this carbonate-dominated margin. These sequence boundaries, in turn, are each associated with marine oxygen isotope events ("Mi Events") and correlate to sequences on the New Jersey margin, the Gulf of Papua, Great Australian Bight, and McMurdo Sound, indicating that these sequences are eustatically controlled. Although sedimentary particle counts only show strong peaks of glauconite at sequence boundaries, the NGR record

  1. Investigation of solar active regions at high resolution by balloon flights of the solar optical universal polarimeter, definition phase

    NASA Technical Reports Server (NTRS)

    Tarbell, Theodore D.; Topka, Kenneth P.

    1992-01-01

    The definition phase of a scientific study of active regions on the sun by balloon flight of a former Spacelab instrument, the Solar Optical Universal Polarimeter (SOUP) is described. SOUP is an optical telescope with image stabilization, tunable filter and various cameras. After the flight phase of the program was cancelled due to budgetary problems, scientific and engineering studies relevant to future balloon experiments of this type were completed. High resolution observations of the sun were obtained using SOUP components at the Swedish Solar Observatory in the Canary Islands. These were analyzed and published in studies of solar magnetic fields and active regions. In addition, testing of low-voltage piezoelectric transducers was performed, which showed they were appropriate for use in image stabilization on a balloon.

  2. A scanning, all-fiber Sagnac interferometer for high resolution magneto-optic measurements at 820 nm

    SciTech Connect

    Fried, Alexander; Fejer, Martin; Kapitulnik, Aharon

    2014-10-15

    The Sagnac Interferometer has historically been used for detecting non-reciprocal phenomena, such as rotation. We demonstrate an apparatus in which this technique is employed for high resolution measurements of the Magneto-Optical Polar Kerr effect—a direct indicator of magnetism. Previous designs have incorporated free-space components which are bulky and difficult to align. We improve upon this technique by using all fiber-optic coupled components and demonstrate operation at a new wavelength, 820 nm, with which we can achieve better than 1 μrad resolution. Mounting the system on a piezo-electric scanner allows us to acquire diffraction limited images with 1.5 μm spatial resolution. We also provide extensive discussion on the details and of the Sagnac Interferometer's construction.

  3. River pollution remediation monitored by optical and infrared high-resolution satellite images.

    PubMed

    Trivero, Paolo; Borasi, Maria; Biamino, Walter; Cavagnero, Marco; Rinaudo, Caterina; Bonansea, Matias; Lanfri, Sofia

    2013-09-01

    The Bormida River Basin, located in the northwestern region of Italy, has been strongly contaminated by the ACNA chemical factory. This factory was in operation from 1892 to 1998, and contamination from the factory has had deleterious consequences on the water quality, agriculture, natural ecosystems and human health. Attempts have been made to remediate the site. The aims of this study were to use high-resolution satellite images combined with a classical remote sensing methodology to monitor vegetation conditions along the Bormida River, both upstream and downstream of the ACNA chemical factory site, and to compare the results obtained at different times before and after the remediation process. The trends of the Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) along the riverbanks are used to assess the effect of water pollution on vegetation. NDVI and EVI values show that the contamination produced by the ACNA factory had less severe effects in the year 2007, when most of the remediation activities were concluded, than in 2006 and 2003. In 2007, the contamination effects were noticeable up to 6 km downstream of the factory, whereas in 2003 and 2006 the influence range was up to about 12 km downstream of the factory. The results of this study show the effectiveness of remediation activities that have been taking place in this area. In addition, the comparison between NDVI and EVI shows that the EVI is more suitable to characterise the vegetation health and can be considered an additional tool to assess vegetation health and to monitor restoration activities. PMID:23456221

  4. River pollution remediation monitored by optical and infrared high-resolution satellite images.

    PubMed

    Trivero, Paolo; Borasi, Maria; Biamino, Walter; Cavagnero, Marco; Rinaudo, Caterina; Bonansea, Matias; Lanfri, Sofia

    2013-09-01

    The Bormida River Basin, located in the northwestern region of Italy, has been strongly contaminated by the ACNA chemical factory. This factory was in operation from 1892 to 1998, and contamination from the factory has had deleterious consequences on the water quality, agriculture, natural ecosystems and human health. Attempts have been made to remediate the site. The aims of this study were to use high-resolution satellite images combined with a classical remote sensing methodology to monitor vegetation conditions along the Bormida River, both upstream and downstream of the ACNA chemical factory site, and to compare the results obtained at different times before and after the remediation process. The trends of the Normalised Difference Vegetation Index (NDVI) and the Enhanced Vegetation Index (EVI) along the riverbanks are used to assess the effect of water pollution on vegetation. NDVI and EVI values show that the contamination produced by the ACNA factory had less severe effects in the year 2007, when most of the remediation activities were concluded, than in 2006 and 2003. In 2007, the contamination effects were noticeable up to 6 km downstream of the factory, whereas in 2003 and 2006 the influence range was up to about 12 km downstream of the factory. The results of this study show the effectiveness of remediation activities that have been taking place in this area. In addition, the comparison between NDVI and EVI shows that the EVI is more suitable to characterise the vegetation health and can be considered an additional tool to assess vegetation health and to monitor restoration activities.

  5. Three-Dimensional High-Resolution Optical/X-Ray Stereoscopic Tracking Velocimetry

    NASA Technical Reports Server (NTRS)

    Cha, Soyoung S.; Ramachandran, Naryanan

    2005-01-01

    Measurement of three-dimensional (3-D) three-component velocity fields is of great importance in a variety of research and industrial applications for understanding materials processing, fluid physics, and strain/displacement measurements. The 3-D experiments in these fields most likely inhibit the use of conventional techniques, which are based only on planar and optically-transparent-field observation. Here, we briefly review the current status of 3-D diagnostics for motion/velocity detection, for both optical and x-ray systems. As an initial step for providing 3-D capabilities, we have developed stereoscopic tracking velocimetry (STV) to measure 3-D flow/deformation through optical observation. The STV is advantageous in system simplicity, for continually observing 3-D phenomena in near real-time. In an effort to enhance the data processing through automation and to avoid the confusion in tracking numerous markers or particles, artificial neural networks are employed to incorporate human intelligence. Our initial optical investigations have proven the STV to be a very viable candidate for reliably measuring 3-D flow motions. With previous activities focused on improving the processing efficiency, overall accuracy, and automation based on the optical system, the current efforts is directed to the concurrent expansion to the x-ray system for broader experimental applications.

  6. Three-Dimensional High-Resolution Optical/X-Ray Stereoscopic Tracking Velocimetry

    NASA Technical Reports Server (NTRS)

    Cha, Soyoung S.; Ramachandran, Narayanan

    2004-01-01

    Measurement of three-dimensional (3-D) three-component velocity fields is of great importance in a variety of research and industrial applications for understanding materials processing, fluid physics, and strain/displacement measurements. The 3-D experiments in these fields most likely inhibit the use of conventional techniques, which are based only on planar and optically-transparent-field observation. Here, we briefly review the current status of 3-D diagnostics for motion/velocity detection, for both optical and x-ray systems. As an initial step for providing 3-D capabilities, we nave developed stereoscopic tracking velocimetry (STV) to measure 3-D flow/deformation through optical observation. The STV is advantageous in system simplicity, for continually observing 3- D phenomena in near real-time. In an effort to enhance the data processing through automation and to avoid the confusion in tracking numerous markers or particles, artificial neural networks are employed to incorporate human intelligence. Our initial optical investigations have proven the STV to be a very viable candidate for reliably measuring 3-D flow motions. With previous activities are focused on improving the processing efficiency, overall accuracy, and automation based on the optical system, the current efforts is directed to the concurrent expansion to the x-ray system for broader experimental applications.

  7. Single-shot, high-resolution, fiber-based phase-diversity photodetection of optical pulses

    NASA Astrophysics Data System (ADS)

    Dorrer, C.; Waxer, L. J.; Kalb, A.; Hill, E. M.; Bromage, J.

    2016-03-01

    Temporally characterizing optical pulses is an important task when building, optimizing, and using optical sources. Direct photodetection with high-bandwidth photodiodes and real-time oscilloscopes is only adequate for optical pulses longer than ~10 ps; diagnostics based on indirect strategies are required to characterize femtosecond and sub-10-ps coherent sources. Most of these diagnostics are based on nonlinear optics and can be difficult to implement for the single-shot characterization of nonrepetitive events. A temporal diagnostic based on phase diversity is demonstrated in the context of picosecond high-energy laser systems, where single-shot pulse measurements are required for system safety and interpretation of experimental results. A plurality of ancillary optical pulses obtained by adding known amounts of chromatic dispersion to the pulse under test are directly measured by photodetection and processed to reconstruct the input pulse shape. This high-sensitivity (~50-pJ) diagnostic is based on a pulse replicator composed of fiber splitters and delay fibers, making it possible to operate with fiber sources and free-space sources after fiber coupling. Experimental data obtained with a high-bandwidth real-time oscilloscope demonstrate accurate characterization of pulses from a high-energy chirped-pulse amplification system, even for pulses shorter than the photodetection impulse response.

  8. X-ray optics. II - A technique for high resolution spectroscopy

    NASA Technical Reports Server (NTRS)

    Cash, Webster C., Jr.

    1991-01-01

    A novel combination of optical elements and properties is combined to achieve high-spectral resolution using grazing incidence optics of modest quality. Analysis and ray tracing of examples show that using radial groove gratings at high blaze angles in the manner of an echelle spectrograph can provide high spectral resolution. This arrangement is compared to the conventional in-plane designs to show that the off-plane is superior in nearly every respect. Cross dispersion can be provided by the energy resolution of a CCD detector. Additional resolution can be squeezed from the system by strategic placement of gratings to take advantage of the azimuthal response of a Wolter X-ray optic.

  9. High resolution capabilities of all-silica cantilevered probes for near-field optical microscopy.

    PubMed

    Descrovi, Emiliano; Aeschimann, Laure; Soboleva, Irina; De Angelis, Francesco; Giorgis, Fabrizio; Di Fabrizio, Enzo

    2009-11-01

    We report on the possibility of performing Near-field Scanning Optical Microscopy in illumination mode by means of microfabricated, metal-coated silica probes based on transparent cantilevers. A low spring constant silica cantilever hosts a silica tip at its end showing an hyperbolic profile and a circular symmetry. After evaporation of 100 nm of aluminium on the tip and the cantilever we processed the tip apex by means of a FIB, thus obtaining either a probe apex with an optical aperture or an apertureless probe having a thin metal layer on the top. An excellent quality of near-field images of samples showing sub-wavelength features is obtained in both case. In particular, the apertureless probe allows highly resolved topographical and optical images to be collected at the same time. This work further demonstrates that the use of completely transparent, metal-coated cantilevers greatly simplify the light injection into the probe and the fabrication process consequently.

  10. High-Resolution Optical and Near-Infrared Imaging of Young Circumstellar Disks

    NASA Technical Reports Server (NTRS)

    McCaughrean, Mark; Stapelfeldt, Karl; Close, Laird

    2000-01-01

    In the past five years, observations at optical and near-infrared wavelengths obtained with the Hubble Space Telescope and ground-based adaptive optics have provided the first well-resolved images of young circumstellar disks which may form planetary systems. We review these two observational techniques and highlight their results by presenting prototype examples of disks imaged in the Taurus-Auriga and Orion star-forming regions. As appropriate, we discuss the disk parameters that may be typically derived from the observations, as well as the implications that the observations may have on our understanding of, for example, the role of the ambient environment in shaping the disk evolution. We end with a brief summary of the prospects for future improvements in space- and ground-based optical/IR imaging techniques, and how they may impact disk studies.

  11. Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging.

    PubMed

    Colchester, Richard J; Zhang, Edward Z; Mosse, Charles A; Beard, Paul C; Papakonstantinou, Ioannis; Desjardins, Adrien E

    2015-04-01

    An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed. PMID:25909031

  12. Broadband miniature optical ultrasound probe for high resolution vascular tissue imaging

    PubMed Central

    Colchester, Richard J.; Zhang, Edward Z.; Mosse, Charles A.; Beard, Paul C.; Papakonstantinou, Ioannis; Desjardins, Adrien E.

    2015-01-01

    An all-optical ultrasound probe for vascular tissue imaging was developed. Ultrasound was generated by pulsed laser illumination of a functionalized carbon nanotube composite coating on the end face of an optical fiber. Ultrasound was detected with a Fabry-Pérot (FP) cavity on the end face of an adjacent optical fiber. The probe diameter was < 0.84 mm and had an ultrasound bandwidth of ~20 MHz. The probe was translated across the tissue sample to create a virtual linear array of ultrasound transmit/receive elements. At a depth of 3.5 mm, the axial resolution was 64 µm and the lateral resolution was 88 µm, as measured with a carbon fiber target. Vascular tissues from swine were imaged ex vivo and good correspondence to histology was observed. PMID:25909031

  13. Characterization of Biogeochemical Variability in a Tidal Estuary Using High Resolution Optical Measurements

    NASA Astrophysics Data System (ADS)

    Chang, G.; Jones, C.; Martin, T.

    2015-12-01

    The Berry's Creek Study Area (BCSA) is a tidal estuary located in New Jersey. Several chemicals of potential concern (COPCs) are present in the BCSA waterway and marshes, including mercury, methyl mercury, and polychlorinated biphenyls. Concentrations of COPCs and suspended solids in the BCSA vary temporally and spatially due to tidal variability, freshwater flow events, and interaction of marsh, waterway, and sediment bed materials. This system-wide variability confounds evaluation of COPC sources and transport mechanisms when using conventional laboratory-based analysis of discrete water column samples. Therefore, an optically-based biogeochemical monitoring program was conducted using near-continuous measurements of optical properties and an optical-biogeochemical partial least-squares regression model pioneered by B. Bergamaschi (USGS) and colleagues. The objective of the study was to characterize COPC concentration dynamics in the BCSA water column and relate the analysis to sediment bed processes. Optical-biogeochemical model results indicated that, in general, measured optical properties were sufficient for predicting COPC concentrations to within 10% of the accuracy of laboratory-based analytical measurements. The continuous, high temporal resolution time series of COPC concentrations determined by the optical-biogeochemical model enabled evaluation of the sediment bed dynamics and variability of COPCs in the surface water of the BCSA. Results indicate that tidally-induced resuspension of waterway sediment bed particulates is the primary mechanism for transport of COPCs to surface water. Waterway-marsh tidal exchange shows a net mass flux of particulate COPCs from waterway to marsh, indicating that particulate COPCs are retained and accumulate in the marshes with relatively little net export of dissolved COPCs from the marshes to the waterway.

  14. Use of tapered amplifier diode laser for biological-friendly high-resolution optical trapping.

    PubMed

    Cheng, Wei; Hou, Ximiao; Ye, Fangmao

    2010-09-01

    A 1064 nm laser is commonly used for biological optical trapping. However, it has the problem of generating reactive oxygen species in the presence of a sensitizer, which leads to photo damage in biological samples. Here we constructed optical tweezers using a tapered amplifier diode laser that operates at 830 nm. Compared to a 1064 nm laser, this laser is friendly to live cells, eliminates photo damage associated with reactive oxygen species, and allows simultaneous two-photon fluorescence imaging of green fluorescent proteins in live mammalian cells. All these advantages could significantly benefit future application of this single molecule technique in biological studies.

  15. Use of tapered amplifier diode laser for biological-friendly high-resolution optical trapping.

    PubMed

    Cheng, Wei; Hou, Ximiao; Ye, Fangmao

    2010-09-01

    A 1064 nm laser is commonly used for biological optical trapping. However, it has the problem of generating reactive oxygen species in the presence of a sensitizer, which leads to photo damage in biological samples. Here we constructed optical tweezers using a tapered amplifier diode laser that operates at 830 nm. Compared to a 1064 nm laser, this laser is friendly to live cells, eliminates photo damage associated with reactive oxygen species, and allows simultaneous two-photon fluorescence imaging of green fluorescent proteins in live mammalian cells. All these advantages could significantly benefit future application of this single molecule technique in biological studies. PMID:20808392

  16. Grazing-incidence high-resolution stigmatic spectrograph with two optical elements.

    PubMed

    Malvezzi, A M; Garifo, L; Tondello, G

    1981-07-15

    Using two optical toroidal elements, a mirror and a grating, both working at grazing incidence, a spectrometer can be built that is stigmatic in the XUV region at one wavelength. Good compensation of the aberrations is achieved when the intermediate sagittal image is nearly at infinity. By varying the angle of incidence on the grating with simple movements, a given couple of optical elements could cover stigmatically a rather extended spectral range. If coupled with bidimensional array detectors, such a spectrograph could find applications in planned solar XUV telescopes.

  17. High Resolution deglacial monsoon δ18O record from a new stalagmite from the Kailash Cave, Central India

    NASA Astrophysics Data System (ADS)

    Allu C, Narayana; Pawan K, Gautam; Shraddha, Band; Madhusudan G, Yadava; Rengaswamy, Ramesh; Shen, Chuan-Chou

    2016-04-01

    High resolution δ18O and δ13C data from absolutely dated stalagmites have been useful for reconstructing the Asian monsoon variability (e.g., Yadava et al., 2004; Laskar et al., 2013; Allu et al., 2014; Lone et al., 2014; Sinha et al., 2015). However, many studies lack high resolution spatial and temporal records leaving significant gaps which need to be filled for a vivid understanding of monsoonal variability. We report here the first high resolution stalagmite δ18O isotope results during the last deglacial obtained from the Kailash cave located from the core monsoon region. The length of stalagmite was 480 mm, with an average diameter of 120 mm. The sample was cut for continuous micro milling at 400μm intervals along the growth axis (using new wave research micro-mill-101288) for the analyses of stable oxygen and carbon isotopes using a Delta V plus IRMS at the Physical Research Laboratory, Ahmedabad. The physical appearance of the sample section reveals very fine, straight and clear laminations from the top to 310 mm from below, which have thick laminae. U-Th dates obtained from a Thermo Fisher NEPTUNE multi-collector inductively coupled plasma mass spectrometer (MC-ICP-MS) at High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), National Taiwan University, Taiwan (Shen et al., 2012) showed the record spanned ~2400 years from ~14.6 ka to ~12.2 ka. Linear Age-Depth model constructed from dates suggests that the sample grew for ~2.400 years from ~14.6 ka to ~12.2 ka with varying resolutions from ~6 months to ~8 years. Hendy's test from 8 distinct layers shows poor correlation between δ18O and δ13C suggesting the isotopic equilibrium conditions at the time of crystallization. δ18O and δ13C results appear to be cyclic in nature varying in the range from +0.37‰ to -6.07‰ and -1.59‰ to -10.59‰ respectively. Enriched δ18O in top portion represents poor monsoon during the onset of Younger Drayas. Later, the δ18O signals

  18. The design of a novel tip enhanced near-field scanning probe microscope for ultra-high resolution optical imaging

    NASA Astrophysics Data System (ADS)

    Nowak, Derek Brant

    Traditional light microscopy suffers from the diffraction limit, which limits the spatial resolution to lambda/2. The current trend in optical microscopy is the development of techniques to bypass the diffraction limit. Resolutions below 40 nm will make it possible to probe biological systems by imaging the interactions between single molecules and cell membranes. These resolutions will allow for the development of improved drug delivery mechanisms by increasing our understanding of how chemical communication within a cell occurs. The materials sciences would also benefit from these high resolutions. Nanomaterials can be analyzed with Raman spectroscopy for molecular and atomic bond information, or with fluorescence response to determine bulk optical properties with tens of nanometer resolution. Near-field optical microscopy is one of the current techniques, which allows for imaging at resolutions beyond the diffraction limit. Using a combination of a shear force microscope (SFM) and an inverted optical microscope, spectroscopic resolutions below 20 nm have been demonstrated. One technique, in particular, has been named tip enhanced near-field optical microscopy (TENOM). The key to this technique is the use of solid metal probes, which are illuminated in the far field by the excitation wavelength of interest. These probes are custom-designed using finite difference time domain (FDTD) modeling techniques, then fabricated with the use of a focused ion beam (FIB) microscope. The measure of the quality of probe design is based directly on the field enhancement obtainable. The greater the field enhancement of the probe, the more the ratio of near-field to far-field background contribution will increase. The elimination of the far-field signal by a decrease of illumination power will provide the best signal-to-noise ratio in the near-field images. Furthermore, a design that facilitates the delocalization of the near-field imaging from the far-field will be beneficial

  19. High-resolution microscope for tip-enhanced optical processes in ultrahigh vacuum

    NASA Astrophysics Data System (ADS)

    Steidtner, Jens; Pettinger, Bruno

    2007-10-01

    An optical microscope based on tip-enhanced optical processes that can be used for studies on adsorbates as well as thin layers and nanostructures is presented. The microscope provides chemical and topographic informations with a resolution of a few nanometers and can be employed in ultrahigh vacuum as well as gas phase. The construction involves a number of improvements compared to conventional instruments. The central idea is to mount, within an UHV system, an optical platform with all necessary optical elements to a rigid frame that also carries the scanning tunneling microscope unit and to integrate a high numerical aperture parabolic mirror between the scanning probe microscope head and the sample. The parabolic mirror serves to focus the incident light and to collect a large fraction of the scattered light. The first experimental results of Raman measurements on silicon samples as well as brilliant cresyl blue layers on single crystalline gold and platinum surfaces in ultrahigh vacuum are presented. For dye adsorbates a Raman enhancement of ˜106 and a net signal gain of up to 4000 was observed. The focus diameter (˜λ/2) was measured by Raman imaging the focal region on a Si surface. The requirements of the parabolic mirror in terms of alignment accuracy were experimentally determined as well.

  20. Fiber-Optic Strain Gauge With High Resolution And Update Rate

    NASA Technical Reports Server (NTRS)

    Figueroa, Fernando; Mahajan, Ajay; Sayeh, Mohammad; Regez, Bradley

    2007-01-01

    An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are useful mainly for measuring small strains (including those associated with vibrations) in such structures as rocket test stands, buildings, oilrigs, bridges, and dams. The technology was inspired by the need to measure very small strains on structures supporting liquid oxygen tanks, as a way to measure accurately mass of liquid oxygen during rocket engine testing. This improved fiber-optic strain gauge was developed to overcome some of the deficiencies of both traditional foil strain gauges and prior fiber-optic strain gauges. Traditional foil strain gages do not have adequate signal-to-noise ratios at such small strains. Fiber-optic strain gauges have been shown to be potentially useful for measuring such small strains, but heretofore, the use of fiberoptic strain gauges has been inhibited, variously, by complexity, cost, or low update rate.

  1. Integration of Permanent Scatterers Analysis and High Resolution Optical Images within Landslide Risk Analysis

    NASA Astrophysics Data System (ADS)

    Farina, P.; Colombo, D.; Fumagalli, A.; Gontier, E.; Moretti, S.

    2004-06-01

    In the framework of the on-going SLAM project (Service for Landslide Monitoring), funded by the European Space Agency (ESA) the Permanent Scatterers processing and the analysis of high resolution images (e.g. SPOT5) have been performed at a basin scale, on the whole territory of the Arno River basin (Central Italy). The project aims at the development of a service based on the integration of EO-data within the current practices used for landslide risk management. The studied area, with a spatial extension of about 9,000 km2, has been chosen for the presence of a high number of mass movements (up today about 20,000 landslides have been mapped and 300 of them have been classified as at high risk from the institutional authorities) and for its significance, in terms of landslide typology and environmental conditions, with respect to the Italian Apennine territory. By considering the technical requirements imposed by the Italian legislation for the documents related to landslide risk management, three products based on EO- data have been defined related to landslide inventory mapping, landslide hazard mapping and landslide monitoring. To this aim, about 350 SAR images have been interferometrically processed by means of the PS technique, detecting about 600,000 PS. The processing of SPOT5 images and aerial-photos, still in progress, have been performed for the extraction of features related to the landslide presence, useful for the geomorphological analysis and, as a consequence in order to give a spatial meaning to the punctual information provided by the PS. This procedure has been coupled with a intense geological interpretation phase characterized by the analysis of traditional in situ monitoring data, ancillary data and the performing of field surveys. The results of the above described methodologies will impact on the current documents used by the Arno Basin Authority for the landslide risk management (e.g. P.A.I., Piano di Assetto Idrogeologico) creating a case

  2. Individual sarcomere length determination from isolated cardiac cells using high-resolution optical microscopy and digital image processing.

    PubMed Central

    Roos, K P; Brady, A J

    1982-01-01

    Discrete sarcomere lengths have been determined from dynamically contracting isolated cardiac cells with a high-speed, high-resolution direct optical imaging system. Calcium-tolerant cardiac cells from the rat are isolated by perfusion with collagenase and hyaluronidase. Individual sarcomere lengths can be determined by directly imaging the cell's striation pattern onto a solid-state charge-coupled device (CCD) detector interfaced with a digital computer. The precision of detection in a real light microscopic optical system is discussed in relation to the type of image detector, optical contract enhancement techniques, and digital image processing. The optical performance of the direct striation pattern image apparatus has been determined empirically with test grids under standard bright-field and Nomarski-differential interference contrast (DIC) conditions for application to real muscle imaging. Discrete striation positions of isolated cells have been detected and followed with high precision during phasic contraction-relaxation cycles down to average sarcomere lengths as short as 1.43 +/- 0.053 microns. The maximum rates of contraction and relaxation are rapid and synchronous in time course along the length of the cell. These results indicate that direct optical imaging can provide an accurate means to monitor discrete striations and sarcomere lengths along the length of Ca2+-tolerant heart cells. Images FIGURE 1 FIGURE 4 PMID:7183337

  3. High-resolution mapping of quantum efficiency of silicon photodiode via optical-feedback laser microthermography

    SciTech Connect

    Cemine, Vernon Julius; Blanca, Carlo Mar; Saloma, Caesar

    2006-09-20

    We map the external quantum efficiency (QE) distribution of a silicon photodiode (PD) sample via a thermographic imaging technique based on optical-feedback laser confocal microscopy. An image pair consisting of the confocal reflectance image and the 2D photocurrent map is simultaneously acquired to delineate the following regions of interest on the sample: the substrate, the n-type region, the pn overlay, and the bonding pad. The 2D QE distribution is derived from the photocurrent map to quantify the optical performance of these sites. The thermal integrity of the sample is then evaluated by deriving the rate of change of QE with temperature T at each point on the silicon PD. These gradient maps function not only as stringent measures of local thermal QE activity but they also expose probable defect locations on the sample at high spatial resolution - a capability that is not feasible with existing bulk measurement techniques.

  4. Fibre-optic coupling to high-resolution CCD and CMOS image sensors

    NASA Astrophysics Data System (ADS)

    van Silfhout, R. G.; Kachatkou, A. S.

    2008-12-01

    We describe a simple method of gluing fibre-optic faceplates to complementary metal oxide semiconductor (CMOS) active pixel and charge coupled device (CCD) image sensors and report on their performance. Cross-sectional cuts reveal that the bonding layer has a thickness close to the diameter of the individual fibres and is uniform over the whole sensor area. Our method requires no special tools or alignment equipment and gives reproducible and high-quality results. The method maintains a uniform bond layer thickness even if sensor dies are mounted at slight angles with their package. These fibre-coupled sensors are of particular interest to X-ray imaging applications but also provide a solution for compact optical imaging systems.

  5. High-resolution optical coherence tomography using self-adaptive FFT and array detection

    NASA Astrophysics Data System (ADS)

    Zhao, Yonghua; Chen, Zhongping; Xiang, Shaohua; Ding, Zhihua; Ren, Hongwu; Nelson, J. Stuart; Ranka, Jinendra K.; Windeler, Robert S.; Stentz, Andrew J.

    2001-05-01

    We developed a novel optical coherence tomographic (OCT) system which utilized broadband continuum generation for high axial resolution and a high numeric-aperture (N.A.) Objective for high lateral resolution (<5 micrometers ). The optimal focusing point was dynamically compensated during axial scanning so that it can be kept at the same position as the point that has an equal optical path length as that in the reference arm. This gives us uniform focusing size (<5 mum) at different depths. A new self-adaptive fast Fourier transform (FFT) algorithm was developed to digitally demodulate the interference fringes. The system employed a four-channel detector array for speckle reduction that significantly improved the image's signal-to-noise ratio.

  6. High-resolution absolute frequency referenced fiber optic sensor for quasi-static strain sensing

    SciTech Connect

    Lam, Timothy T.-Y.; Chow, Jong H.; Shaddock, Daniel A.; Littler, Ian C. M.; Gagliardi, Gianluca; Gray, Malcolm B.; McClelland, David E.

    2010-07-20

    We present a quasi-static fiber optic strain sensing system capable of resolving signals below nanostrain from 20 mHz. A telecom-grade distributed feedback CW diode laser is locked to a fiber Fabry-Perot sensor, transferring the detected signals onto the laser. An H{sup 13}C{sup 14}N absorption line is then used as a frequency reference to extract accurate low-frequency strain signals from the locked system.

  7. A High-Resolution Mid- to Late-Holocene Sea-Surface Temperature Record from the Subtropics, Baja California, Mexico

    NASA Astrophysics Data System (ADS)

    Coombs, M.; Herguera, J. C.; Lea, D. W.

    2004-12-01

    San Lazaro basin provides a unique environment in which to study paleoclimate because it lies at the intersection of the cooler California Current that originates to the north and the warmer Pacific tropical current that originates to the south. Studies in this basin will provide insight into the varying strength of these currents at decadal and centennial resolutions. In addition, the present-day basin is suboxic (<3 uM/kg), and laminations throughout the top ˜6 m of ocean floor sediments indicate that it may have been suboxic for the past ˜6.5 ky. Suboxia is advantageous in the study of high-resolution paleoclimate records, as lower levels of oxygen inhibit the activity of sediment-disturbing organisms that might smooth climate records. We will present parts of a new decadal-resolution sea-surface temperature (SST) record from San Lazaro (AKA Soledad) basin, Baja California, Mexico. We estimate SST using Mg/Ca and d18O data measured on surface-dwelling planktonic foraminifera Globigerinoides ruber and Globigerina bulloides from ocean-sediment giant box core MD02-2506C2. This 4.6-m core exhibits an ˜0.8 mm/yr sedimentation rate (van Geen et al., 2003) and represents the period ˜5,000 to ˜500 years BP. We sampled the core at 1-cm continuous (i.e., approximately decadal) resolution. Preliminary results indicate that Mg/Ca values for G. ruber range between 2.3 and 3.3 mmol/mol ( ˜20 and ˜24 deg C), with higher values characteristic of the mid-Holocene. Annual sea-surface temperatures for the period 1950 to 1990 ranged between ˜19 and ˜23 deg C (CalCOFI, COADS), suggesting that mid- to late-Holocene SST values were ˜1 deg C higher than the those of the last half century. We will compare our SST proxy results with d18O records from Santa Barbara basin (e.g., Kennett and Kennett, 2000); tree-ring records from Baja California (Bullock, 2003) and Southern California (De Nava et al., 1999); and pluvial (Davis, 2003) and packrat midden (Clark and Sankey, 1999

  8. Carbon cycle dynamics and solar activity embedded in a high-resolution 14C speleothem record from Belize, Central America

    NASA Astrophysics Data System (ADS)

    Lechleitner, Franziska A.; Breitenbach, Sebastian F. M.; McIntyre, Cameron; Asmerom, Yemane; Prufer, Keith M.; Polyak, Victor; Culleton, Brendan J.; Kennett, Douglas J.; Eglinton, Timothy I.; Baldini, James U. L.

    2015-04-01

    Speleothem 14C has recently emerged as a potentially powerful proxy for climate reconstruction. Several studies have highlighted the link between karst hydrology and speleothem 14C content, and a number of possible causes for this relationship have been proposed, such as dripwater flow dynamics in the karst and changes in soil organic matter (SOM) turnover time (e.g. Griffiths et al., 2012). Here we present a high resolution 14C record for a stalagmite (YOK-I) from Yok Balum cave in southern Belize, Central America. YOK-I grew continuously over the last 2000 years, and has been dated very precisely with the U-Th method (40 dates, mean uncertainty < 10 years). The excellent chronological control for this stalagmite allows us to calculate 14C activity (a14C) at the time of speleothem deposition (a14Cinit), as well as the dead carbon fraction (DCF), predominantly a measure of the reservoir effect introduced by limestone dissolution in the karst (Genty et al., 2001). Both records show striking similarities to atmospheric a14C (IntCal13) and reconstructions of solar activity and 14C production rate. We infer close coupling between cave environment and atmosphere, with minimal signal dampening, an observation supported by monitoring data (Ridley et al., in press). DCF fluctuates between approximately 10% and 16% over the entire record, with distinctly lower DCF values and higher a14Cinit during a period of reduced rainfall between ca. 700-1100 AD (linked to the Classic Maya Collapse). This behavior is consistent with observations made elsewhere, and suggests that DCF responds to karst hydrological variability, specifically open-closed system transitions. YOK-I a14Cinit typically lags atmospheric values by 10-100 cal years. A shorter lag appears to be linked to periods of drought, suggesting a response of SOM dynamics above the cave to rainfall reduction. Specifically, drought is inferred to lead to reduced bioproductivity and soil carbon turnover, lowering contributions

  9. Optical design of high resolution and large format CCD airborne remote sensing camera on unmanned aerial vehicle

    NASA Astrophysics Data System (ADS)

    Qian, Yixian; Cheng, Xiaowei; Shao, Jie

    2010-11-01

    Unmanned aerial vehicle remote sensing (UAVRS) is lower in cost, flexible on task arrangement and automatic and intelligent in application, it has been used widely for mapping, surveillance, reconnaissance and city planning. Airborne remote sensing missions require sensors with both high resolution and large fields of view, large format CCD digital airborne imaging systems are now a reality. A refractive system was designed to meet the requirements with the help of code V software, It has a focal length of 150mm, F number of 5.6, waveband of 0.45~0.7um, and field of view reaches 20°. It is shown that the value of modulation transfer function is higher than 0.5 at 55lp/mm, distortion is less than 0.1%, image quality reaches the diffraction limit. The system with large format CCD and wide field can satisfy the demand of the wide ground overlay area and high resolution. The optical system with simpler structure, smaller size and lighter weight, can be used in airborne remote sensing.

  10. Multi-sensor fusion of electro-optic and infrared signals for high resolution visible images: part I

    NASA Astrophysics Data System (ADS)

    Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor

    2013-06-01

    Electro-Optic (EO) image sensors exhibit the properties of high resolution and low noise level, but they cannot reflect information about the temperature of objects and do not work in dark environments. On the other hand, infrared (IR) image sensors exhibit the properties of low resolution and high noise level, but IR images can reflect information about the temperature of objects all the time. Therefore, in this paper, we propose a novel framework to enhance the resolution of EO images using the information (e.g., temperature) from IR images, which helps distinguish temperature variation of objects in the daytime via high-resolution EO images. The proposed novel framework involves four main steps: (1) select target objects with temperature variation in original IR images; (2) fuse original RGB color (EO) images and IR images based on image fusion algorithms; (3) blend the fused images of target objects in proportion with original gray-scale EO images; (4) superimpose the target objects' temperature information, onto original EO images via the modified NTSC color space transformation. Therein, the image fusion step will be conducted by qualitative (frame pipeline) approach. Revealing temperature information in EO images for the first time is the most significant contribution of this paper. Simulation results will show the transformed EO images with the targets' temperature information.

  11. Optical depth of the Martian atmosphere and surface albedo from high-resolution orbiter images

    NASA Astrophysics Data System (ADS)

    Petrova, E. V.; Hoekzema, N. M.; Markiewicz, W. J.; Thomas, N.; Stenzel, O. J.

    2012-01-01

    In this paper we describe and evaluate the so-called shadow method. This method can be used to estimate the optical depth of the Martian atmosphere from the differences in brightness between shadowed and sunlit regions observed from an orbiter. We present elaborate and simplified versions of the method and analyze the capabilities and the sources of errors. It proves essential to choose shadowed and sunlit comparison regions with similar surface properties. Accurate knowledge of the observing geometry, including the slopes of the observed region, is important as well, since the procedure should be corrected for the non-horizontal surface. Moreover, the elaborate version of the shadow method can be sensitive to (i) the optical model of aerosols and (ii) the assumed bi-directional reflectance function of the surface. To obtain reliable estimates, the analyzed images must have a high spatial resolution, which the HiRISE camera onboard the MRO provides. We tested the shadow method on two HiRISE images of Victoria crater (TRA_0873_1780 and PSP_001414_1780) that were taken while this crater was the exploration site of the Opportunity rover. While the rover measured optical depth τ approximately in the ranges from 0.43 to 0.53 and from 0.53 to 0.59 by imaging the sun, our shadow procedure yielded τ about 0.50 and 0.575, respectively (from the HiRISE's red images). Thus, the agreement is quite good. The obtained estimates of the surface albedo are about 0.20 and 0.17, respectively.

  12. High-resolution adaptive optics scanning laser ophthalmoscope with multiple deformable mirrors

    DOEpatents

    Chen, Diana C.; Olivier, Scot S.; Jones; Steven M.

    2010-02-23

    An adaptive optics scanning laser ophthalmoscopes is introduced to produce non-invasive views of the human retina. The use of dual deformable mirrors improved the dynamic range for correction of the wavefront aberrations compared with the use of the MEMS mirror alone, and improved the quality of the wavefront correction compared with the use of the bimorph mirror alone. The large-stroke bimorph deformable mirror improved the capability for axial sectioning with the confocal imaging system by providing an easier way to move the focus axially through different layers of the retina.

  13. Compact, low-cost, and high-resolution interrogation unit for optical sensors

    SciTech Connect

    Kiesel, Peter; Schmidt, Oliver; Mohta, Setu; Johnson, Noble; Malzer, Stefan

    2006-11-13

    Compact wavelength detectors that resolve wavelength changes in the subpicometer range over a broad spectral range are presented. A photodiode array or position sensor device is coated with a linear variable filter that converts the wavelength of the incident light into a spatial intensity distribution. The centroid of the spatial distribution is determined by a differential readout of the two elements of the photodiode array or the position sensor device. The device can interrogate any optical sensor that produces a wavelength shift in response to a stimulus. The potential of this device was tested by interrogating fiber-Bragg-grating sensors.

  14. High-resolution in vivo optical imaging of stroke injury and repair

    PubMed Central

    Sakadžić, Sava; Lee, Jonghwan; Boas, David A.; Ayata, Cenk

    2015-01-01

    Central nervous system (CNS) function and dysfunction are best understood within a framework of interactions between neuronal, glial and vascular compartments comprising the neurovascular unit (NVU), all of which contribute to stroke-induced CNS injury, plasticity, repair, and recovery. Recent advances in in vivo optical microscopy have enabled us to observe and interrogate cells and their processes with high spatial resolution in real time and in their natural environment deep in the brain tissue. Here, we review some of these state-of-the-art imaging techniques with an emphasis on imaging the interactions among the constituents of the NVU during ischemic injury and repair in small animal models. PMID:25960347

  15. High resolution kilometric range optical telemetry in air by radio frequency phase measurement

    NASA Astrophysics Data System (ADS)

    Guillory, Joffray; Šmíd, Radek; García-Márquez, Jorge; Truong, Daniel; Alexandre, Christophe; Wallerand, Jean-Pierre

    2016-07-01

    We have developed an optical Absolute Distance Meter (ADM) based on the measurement of the phase accumulated by a Radio Frequency wave during its propagation in the air by a laser beam. In this article, the ADM principle will be described and the main results will be presented. In particular, we will emphasize how the choice of an appropriate photodetector can significantly improve the telemeter performances by minimizing the amplitude to phase conversion. Our prototype, tested in the field, has proven its efficiency with a resolution better than 15 μm for a measurement time of 10 ms and distances up to 1.2 km.

  16. Quasi-microscope concept for planetary missions. [optically augmented lander camera for high resolution microscopy

    NASA Technical Reports Server (NTRS)

    Huck, F. O.; Burcher, E. E.; Wall, S. D.; Arvidson, R. E.; Giat, O.

    1977-01-01

    Viking lander cameras have returned stereo and multispectral views of the Martian surface with a resolution that approaches 2 mm/lp in the near field. A two-orders-of-magnitude increase in resolution could be obtained for collected surface samples by augmenting these cameras with auxiliary optics that would neither impose special camera design requirements nor limit the cameras field of view of the terrain. Quasi-microscope images would provide valuable data on the physical and chemical characteristics of planetary regoliths.

  17. High resolution kilometric range optical telemetry in air by radio frequency phase measurement.

    PubMed

    Guillory, Joffray; Šmíd, Radek; García-Márquez, Jorge; Truong, Daniel; Alexandre, Christophe; Wallerand, Jean-Pierre

    2016-07-01

    We have developed an optical Absolute Distance Meter (ADM) based on the measurement of the phase accumulated by a Radio Frequency wave during its propagation in the air by a laser beam. In this article, the ADM principle will be described and the main results will be presented. In particular, we will emphasize how the choice of an appropriate photodetector can significantly improve the telemeter performances by minimizing the amplitude to phase conversion. Our prototype, tested in the field, has proven its efficiency with a resolution better than 15 μm for a measurement time of 10 ms and distances up to 1.2 km.

  18. High resolution kilometric range optical telemetry in air by radio frequency phase measurement.

    PubMed

    Guillory, Joffray; Šmíd, Radek; García-Márquez, Jorge; Truong, Daniel; Alexandre, Christophe; Wallerand, Jean-Pierre

    2016-07-01

    We have developed an optical Absolute Distance Meter (ADM) based on the measurement of the phase accumulated by a Radio Frequency wave during its propagation in the air by a laser beam. In this article, the ADM principle will be described and the main results will be presented. In particular, we will emphasize how the choice of an appropriate photodetector can significantly improve the telemeter performances by minimizing the amplitude to phase conversion. Our prototype, tested in the field, has proven its efficiency with a resolution better than 15 μm for a measurement time of 10 ms and distances up to 1.2 km. PMID:27475593

  19. Paleoseismic inferences from a high-resolution marine sedimentary record in northern Chile (23°S)

    NASA Astrophysics Data System (ADS)

    Vargas, Gabriel; Ortlieb, Luc; Chapron, Emmanuel; Valdes, Jorge; Marquardt, Carlos

    2005-04-01

    The active margin of northern Chile is characterized by strong seismic events which induce gravity instability for sedimentary sequences located along the outer forearc of the Andean range. Even though the narrow continental platform of this area limits the accumulation of marine sediments, a detailed paleoceanographic reconstruction, using high-resolution sedimentological and geochronological techniques, of a Holocene sedimentary sequence in Mejillones bay (23°S) provides important tools to infer the occurrence of past great subduction earthquakes and/or associated tsunamis. From the analyses of short cores retrieved in this shallow marine basin, we infer the occurrence of two strong seismic events during historical times. The first one, dated between the years 1409 and 1449 AD, produced an angular unconformity and associated lenticular coarse-grained deposits generated after local reworking of shallower material. The second one, dated between the years 1754 and 1789 AD, caused slumping, erosive processes and local reworking of material. The analysis of seismic profile data acquired in this bay allowed the recognition of a major slump deposit within the upper sedimentary sequence, tentatively dated as of Middle Holocene age. This event might record the greatest earthquake (and tsunami) affecting the basin within the last few thousand years. We interpret that destabilization of sediments occurs most probably in response to local reactivation of faults within the Mejillones peninsula during strong earthquakes, especially the Mejillones fault.

  20. High-resolution depositional records of polycyclic aromatic hydrocarbons in the central continental shelf mud of the East China Sea

    SciTech Connect

    Zhigang Guo; Tian Lin; Gan Zhang; Zuosheng Yang; Ming Fang

    2006-09-01

    A well-placed {sup 210}Pb-dated sediment core extracted from the distal mud in the central continental shelf of the East China Sea is used to reconstruct the high-resolution atmospheric depositional record of polycyclic aromatic hydrocarbons (PAHs), believed to be transported mainly from China in the past 200 years due to the East Asian Monsoon. Total PAHs (TPAHs), based on the 16 USEPA priority PAHs, range from 27 in 1788 to 132 ng g{sup -1} in 2001. TPAH variation in the core reflects energy usage changes and follows closely the historical economic development in China. PAHs in the core are dominantly pyrogenic in source, i.e., they are mainly from the incomplete combustion of coal and biomass burning. Several individual PAHs suggest that contribution from incomplete petroleum combustion has increased during recent years. Analysis of the 2 + 3 ring and the 5 + 6 ring PAHs and principle component analysis provide more evidence in the change in the energy structure, especially after 1978 when China embarked on the 'Reform and Open' Policy, indicating the transformation from an agricultural to an industrial economy of China. The historical profile of PAH distribution in the study area is obviously different from the United States and Europe due to their difference in energy structure and economic development stages. 39 refs., 5 figs.

  1. A Boreal high-resolution d13C-carb record of the Albian-Cenomanian transition from NW Germany

    NASA Astrophysics Data System (ADS)

    Bornemann, André; Erbacher, Jochen; Heldt, Matthias; Wilmsen, Markus; Lübke, Nathalie; Heimhofer, Ulrich

    2015-04-01

    . London Spec. Publ., 104, 11-24. Stoll, H.M., Schrag, D.P. (2000). High-resolution stable isotope records from the Upper Cretaceous rocks of Italy and Spain: Glacial episodes in a greenhouse planet? Geol. Soc. Am. Bull., 112, 308-319.

  2. High-Resolution Adaptive Optics Scanning Laser Ophthalmoscope with Dual Deformable Mirrors

    SciTech Connect

    Chen, D C; Jones, S M; Silva, D A; Olivier, S S

    2006-08-11

    Adaptive optics scanning laser ophthalmoscope (AO SLO) has demonstrated superior optical quality of non-invasive view of the living retina, but with limited capability of aberration compensation. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina. We used a bimorph mirror to correct large-stroke, low-order aberrations and a MEMS mirror to correct low-stroke, high-order aberration. The measured ocular RMS wavefront error of a test subject was 240 nm without AO compensation. We were able to reduce the RMS wavefront error to 90 nm in clinical settings using one deformable mirror for the phase compensation and further reduced the wavefront error to 48 nm using two deformable mirrors. Compared with that of a single-deformable-mirror SLO system, dual AO SLO offers much improved dynamic range and better correction of the wavefront aberrations. The use of large-stroke deformable mirrors provided the system with the capability of axial sectioning different layers of the retina. We have achieved diffraction-limited in-vivo retinal images of targeted retinal layers such as photoreceptor layer, blood vessel layer and nerve fiber layers with the combined phase compensation of the two deformable mirrors in the AO SLO.

  3. High-resolution all-optical photoacoustic imaging system for remote interrogation of biological specimens

    NASA Astrophysics Data System (ADS)

    Sampathkumar, Ashwin

    2014-05-01

    Conventional photoacoustic imaging (PAI) employs light pulses to produce a photoacoustic (PA) effect and detects the resulting acoustic waves using an ultrasound transducer acoustically coupled to the target tissue. The resolution of conventional PAI is limited by the sensitivity and bandwidth of the ultrasound transducer. We have developed an all-optical versatile PAI system for characterizing ex vivo and in vivo biological specimens. The system employs noncontact interferometric detection of the acoustic signals that overcomes limitations of conventional PAI. A 532-nm pump laser with a pulse duration of 5 ns excited the PA effect in tissue. Resulting acoustic waves produced surface displacements that were sensed using a 532-nm continuous-wave (CW) probe laser in a Michelson interferometer with a GHz bandwidth. The pump and probe beams were coaxially focused using a 50X objective giving a diffraction-limited spot size of 0.48 μm. The phase-encoded probe beam was demodulated using a homodyne interferometer. The detected time-domain signal was time reversed using k-space wave-propagation methods to produce a spatial distribution of PA sources in the target tissue. Performance was assessed using PA images of ex vivo rabbit lymph node specimens and human tooth samples. A minimum peak surface displacement sensitivity of 0.19 pm was measured. The all-optical PAI (AOPAI) system is well suited for assessment of retinal diseases, caries lesion detection, skin burns, section less histology and pressure or friction ulcers.

  4. A simple fiber-optic microprobe for high resolution light measurements: application in marine sediment

    NASA Technical Reports Server (NTRS)

    Jorgensen, B. B.; Des Marais, D. J.

    1986-01-01

    A fiber-optic microphobe is described which is inexpensive and simple to build and use. It consists of an 80-micrometers optical fiber which at the end is tapered down to a rounded sensing tip of 20-30-micrometers diameter. The detector is a hybrid photodiode/amplifier. The probe has a sensitivity of 0.01 microEinst m-2 s-1 and a spectral range of 300-1,100 nm. Spectral light gradients were measured in fine-grained San Francisco Bay sediment that had an undisturbed diatom coating on the surface. The photic zone of the mud was only 0.4 mm deep. Measured in situ spectra showed extinction maxima at 430-520, 620-630, 670, and 825-850 nm due to absorption by chlorophyll a, carotenoids, phycocyanin, and bacterio-chlorophyll a. Maximum light penetration in the visible range was found in both the violet and the red < or = 400 and > or = 700 nm.

  5. A simple fiber-optic microprobe for high resolution light measurements: application in marine sediment.

    PubMed

    Jorgensen, B B; Des Marais, D J

    1986-01-01

    A fiber-optic microphobe is described which is inexpensive and simple to build and use. It consists of an 80-micrometers optical fiber which at the end is tapered down to a rounded sensing tip of 20-30-micrometers diameter. The detector is a hybrid photodiode/amplifier. The probe has a sensitivity of 0.01 microEinst m-2 s-1 and a spectral range of 300-1,100 nm. Spectral light gradients were measured in fine-grained San Francisco Bay sediment that had an undisturbed diatom coating on the surface. The photic zone of the mud was only 0.4 mm deep. Measured in situ spectra showed extinction maxima at 430-520, 620-630, 670, and 825-850 nm due to absorption by chlorophyll a, carotenoids, phycocyanin, and bacterio-chlorophyll a. Maximum light penetration in the visible range was found in both the violet and the red < or = 400 and > or = 700 nm. PMID:11542043

  6. Optical sedimentation recorder

    SciTech Connect

    Bishop, James K.B.

    2014-05-06

    A robotic optical sedimentation recorder is described for the recordation of carbon flux in the oceans wherein both POC and PIC particles are captured at the open end of a submersible sampling platform, the captured particles allowed to drift down onto a collection plate where they can be imaged over time. The particles are imaged using three separate light sources, activated in sequence, one source being a back light, a second source being a side light to provide dark field illumination, and a third source comprising a cross polarized light source to illuminate birefringent particles. The recorder in one embodiment is attached to a buoyancy unit which is capable upon command for bringing the sedimentation recorder to a programmed depth below the ocean surface during recordation mode, and on command returning the unit to the ocean surface for transmission of recorded data and receipt of new instructions. The combined unit is provided with its own power source and is designed to operate autonomously in the ocean for extended periods of time.

  7. Radiocarbon variability in the western equatorial Pacific inferred from a high-resolution coral record from Nauru Island

    SciTech Connect

    Guilderson, T.P.; Schrag, D.P.; Kashgarian, M.; Southon, J.

    1998-10-01

    We have generated a high resolution coral {Delta}{sup 14}C record spanning the last 50 years to document the seasonal and interannual redistribution of surface waters in the western tropical Pacific. Prebomb (1947{endash}1956) {Delta}{sup 14}C values average {minus}63{per_thousand} and have a total range of 30{per_thousand}. Values begin to increase in 1957, reaching a maximum of 137{per_thousand} in mid-1983. Large interannual variability of up to 80{per_thousand} closely follows the El Ni{tilde n}o-Southern Oscillation (ENSO). During each ENSO warm phase, {Delta}{sup 14}C values begin to increase, reflecting the reduction of low-{sup 14}C water upwelling in the east and the invasion of subtropical water into the western equatorial tropical Pacific. Maximum {Delta}{sup 14}C values are in phase or lag the corresponding sea surface temperature maxima in the eastern tropical Pacific, whereas the rapid return to more negative {Delta}{sup 14}C is in phase with eastern Pacific ENSO indices. The highest-amplitude excursions occur during the 1965/1966 and 1972/1973 events, when the {sup 14}C contrast is highest between the eastern Pacific and subtropics. The 1982/1983 El Ni{tilde n}o, although a larger ENSO event, has a lower {Delta}{sup 14}C amplitude, reflecting the penetration of bomb radiocarbon into the equatorial undercurrent and the reduced contrast in {Delta}{sup 14}C between thermocline and subtropical surface waters at that time. This coral record demonstrates the potential for using similar radiocarbon time series for documenting variability in Pacific shallow circulation over interannual and decadal timescales. {copyright} 1998 American Geophysical Union

  8. Mirrors for High Resolution X-Ray Optics---Figure Preserving IR/PT Coating

    NASA Technical Reports Server (NTRS)

    Chan, Kai-Wing; Olsen, Lawrence; Sharpe, Marton; Numata, Ai; McClelland, Ryan; Saha, Timo; Zhang, Will

    2016-01-01

    Coating stress of 10 - 20 nm of Ir is sufficiently high to distort the figure of arc-second thin lightweight mirrors. For iridium: --Stress sigma 4 GPa for 15 nm film implies 60 Nm integrated stress-- Need less than 3 N/m (or stress less than 200 MPa) for sub-arcsecond optics. Basic Approaches for Mitigation. A. Annealing the film-- Glass can be heat up to 400 C without distortion. Silicon is even more resistant.-- It was found that recovery is limited by residual thermal stress from taking the mirror down from high T. B. Coating bi-layer films with compressive stress with tensile stress. C. Front-and-back coating with magnetron sputtering or atomic layer deposition-- Sputtering involve spanning of substrates. Geometric difference in setup (convexness/concaveness of curved mirrors) does not permit precise front-and-back matching-- Atomic layer deposition can provide a uniform deposition front and back simultaneously.

  9. High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics

    PubMed Central

    Crecea, Vasilica; Graf, Benedikt W.; Kim, Taewoo; Popescu, Gabriel; Boppart, Stephen A.

    2014-01-01

    We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells. PMID:25400496

  10. High Resolution Phase-Sensitive Magnetomotive Optical Coherence Microscopy for Tracking Magnetic Microbeads and Cellular Mechanics.

    PubMed

    Crecea, Vasilica; Graf, Benedikt W; Kim, Taewoo; Popescu, Gabriel; Boppart, Stephen A

    2014-03-01

    We present a real-time multimodal near-infrared imaging technology that tracks externally induced axial motion of magnetic microbeads in single cells in culture. The integrated multimodal imaging technique consists of phase-sensitive magnetomotive optical coherence microscopy (MM-OCM) and multiphoton microscopy (MPM).MPMis utilized for the visualization of multifunctional fluorescent and magnetic microbeads, while MM-OCM detects, with nanometer-scale sensitivity, periodic displacements of the microbeads induced by the modulation of an external magnetic field. Magnetomotive signals are measured from mouse macrophages, human breast primary ductal carcinoma cells, and human breast epithelial cells in culture, and validated with full-field phase-sensitive microscopy. This methodology demonstrates the capability for imaging controlled cell dynamics and has the potential for measuring cell biomechanical properties, which are important in assessing the health and pathological state of cells.

  11. High-resolution, lensless endoscope based on digital scanning through a multimode optical fiber

    PubMed Central

    Papadopoulos, Ioannis N.; Farahi, Salma; Moser, Christophe; Psaltis, Demetri

    2013-01-01

    We propose and experimentally demonstrate an ultra-thin rigid endoscope (450 μm diameter) based on a passive multimode optical fiber. We use digital phase conjugation to overcome the modal scrambling of the fiber to tightly focus and scan the laser light at its distal end. By exploiting the maximum number of modes available, sub-micron resolution, high quality fluorescence images of neuronal cells were acquired. The imaging system is evaluated in terms of fluorescence collection efficiency, resolution and field of view. The small diameter of the proposed endoscope, along with its high quality images offer an opportunity for minimally invasive medical endoscopic imaging and diagnosis based on cellular phenotype via direct tissue penetration. PMID:23411747

  12. High resolution spectral optical coherence tomography for clinical imaging of the anterior segment of the eye

    NASA Astrophysics Data System (ADS)

    Szkulmowska, Anna; Gorczynska, Iwona; Szkulmowski, Maciej; Targowski, Piotr; Kowalczyk, Andrzej; Kaluzny, Bartlomiej J.

    2005-08-01

    The aim of this article is to demonstrate an application of Spectral Optical Coherence Tomography SOCT for visualization of the anterior segment of the human eye. A SOCT system with an axial resolution of 4-6 μm and a lateral one of 10 μm provides tomograms composed of 3000 - 5000 A-scans when a total acquisition time of 100-250 ms is used to acquire tomograms. The quality of the images is adequate for detailed evaluation of the corneal structure and contact lens fit. Erosion of the epithelium, scars and lesions may be precisely localized. The design, shape and edge position of the contact lens, as well as other fitting relationships between the lens and the ocular surface, may be accurately assessed. The information provided by SOCT may be helpful in diagnosis, evaluation and documentation of corneal pathologies and contact lens complications.

  13. Affordable and Lightweight High-Resolution X-ray Optics for Astronomical Missions

    NASA Technical Reports Server (NTRS)

    Zhang, W. W.; Biskach, M. P.; Bly, V. T.; Carter, J. M.; Chan, K. W.; Gaskin, J. A.; Hong, M.; Hohl, B. R.; Jones, W. D.; Kolodziejczak, J. J.

    2014-01-01

    Future x-ray astronomical missions require x-ray mirror assemblies that provide both high angular resolution and large photon collecting area. In addition, as x-ray astronomy undertakes more sensitive sky surveys, a large field of view is becoming increasingly important as well. Since implementation of these requirements must be carried out in broad political and economical contexts, any technology that meets these performance requirements must also be financially affordable and can be implemented on a reasonable schedule. In this paper we report on progress of an x-ray optics development program that has been designed to address all of these requirements. The program adopts the segmented optical design, thereby is capable of making both small and large mirror assemblies for missions of any size. This program has five technical elements: (1) fabrication of mirror substrates, (2) coating, (3) alignment, (4) bonding, and (5) mirror module systems engineering and testing. In the past year we have made progress in each of these five areas, advancing the angular resolution of mirror modules from 10.8 arc-seconds half-power diameter reported (HPD) a year ago to 8.3 arc-seconds now. These mirror modules have been subjected to and passed all environmental tests, including vibration, acoustic, and thermal vacuum. As such this technology is ready for implementing a mission that requires a 10-arc-second mirror assembly. Further development in the next two years would make it ready for a mission requiring a 5-arc-second mirror assembly. We expect that, by the end of this decade, this technology would enable the x-ray astrophysical community to compete effectively for a major x-ray mission in the 2020s that would require one or more 1-arc-second mirror assemblies for imaging, spectroscopic, timing, and survey studies.

  14. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    PubMed

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated. PMID:26512484

  15. Interrogation of a linearly chirped fiber Bragg grating sensor with high resolution using a linearly chirped optical waveform.

    PubMed

    Wang, Yiping; Zhang, Jiejun; Coutinho, Olympio; Yao, Jianping

    2015-11-01

    An approach to the interrogation of a linearly chirped fiber Bragg grating (LCFBG) sensor using a linearly frequency-modulated (or chirped) optical waveform (LFMOW) with a high resolution is proposed and experimentally demonstrated. An LFMOW is generated at a laser diode through linear frequency modulation. The generated LFMOW is then launched into an LCFBG pair consisting of two identical LCFBGs, with one serving as a sensing LCFBG and the other as a reference LCFBG. The reflection of the LFMOW from the two LCFBGs would lead to two time delayed LFMOWs. By beating the LFMOWs at a photodetector, a microwave signal with a beat frequency that is proportional to the time delay difference between the two reflected LFMOWs is generated. By measuring the frequency change of the beat signal, the strain applied to the sensing LCFBG is estimated. The proposed approach is experimentally evaluated. An LCFBG sensor with a resolution of 0.25 με is experimentally demonstrated.

  16. A stable and high resolution optical waveguide biosensor based on dense TiO2/Ag multilayer film

    NASA Astrophysics Data System (ADS)

    Jin, Zhao; Guan, Weiming; Liu, Chang; Xue, Tianyu; Wang, Qiyu; Zheng, Weitao; Cui, Xiaoqiang

    2016-07-01

    Optical waveguide (OWG) biosensor has attracted much attention according to the high sensitivity and resolution compared with conventional surface plasmon resonance (SPR) biosensor. Nanoporous materials are usually used as the waveguide layer for absorbing analytes into the porous structure and enhancing the sensor signal. However, this kind of waveguide layer provides poor protection to the metal film and leads to the damage of the biosensor. Ag film can provide great sensitivity in SPR sensing comparing to other metal but was rarely used because of its poor chemical stability. Fabricating high stability Ag based SPR biosensor is still a challenge. In this work we produce an OWG biosensor using a dense TiO2 film as the waveguide layer which provides high resolution and remarkable protection to the metal film. This waveguide structure makes long time detection possible using Ag as the metal layer and is able to lead an enhancement of sensitivity comparing to the Au-based biosensor.

  17. High resolution scanning optical imaging of a frozen polymer p-n junction

    NASA Astrophysics Data System (ADS)

    AlTal, Faleh; Gao, Jun

    2016-09-01

    Semiconductor homojunctions such as p-n or p-i-n junctions are the building blocks of many semiconductor devices such as diodes, photodetectors, transistors, or solar cells. The determination of junction depletion width is crucial for the design and realization of high-performance devices. The polymer analogue of a conventional p-n or p-i-n junction can be created by in situ electrochemical doping in a polymer light-emitting electrochemical cell (LEC). As a result of doping and junction formation, the LECs possess some highly desirable device characteristics. The LEC junction, however, is still poorly understood due to the difficulties of characterizing a dynamic-junction device. Here, we report concerted optical-beam-induced-current (OBIC) and scanning photoluminescence (PL) imaging studies of planar LECs that have been frozen to preserve the doping profile. By optimizing the cell composition, the electrode work function, and the turn-on conditions, we realize a long, straight, and highly emissive p-n junction with an interelectrode spacing of 700 μm. The extremely broad planar cell allows for time-lapse fluorescence imaging of the in situ electrochemical doping process and detailed scanning of the entire cell. A total of eighteen scans at seven locations along the junction have been performed using a versatile, custom cryogenic laser scanning apparatus. The Gaussian OBIC profiles yield an average 1/e2 junction width of only 1.5 μm, which is the smallest ever reported in a planar LEC. The controlled dedoping of the frozen device via warming cycles leads to an unexpectedly narrower OBIC profile, suggesting the presence and disappearance of fine structures at the edges of the frozen p-n junction. The results reported in this work provide new insight into the nature and structure of the LEC p-n junction. Since only about 0.2% of the entire device area is photoactive in response to an incident optical beam, the effective junction width (or volume) must be

  18. Three-dimensional motion tracking for high-resolution optical microscopy, in vivo.

    PubMed

    Bakalar, M; Schroeder, J L; Pursley, R; Pohida, T J; Glancy, B; Taylor, J; Chess, D; Kellman, P; Xue, H; Balaban, R S

    2012-06-01

    When conducting optical imaging experiments, in vivo, the signal to noise ratio and effective spatial and temporal resolution is fundamentally limited by physiological motion of the tissue. A three-dimensional (3D) motion tracking scheme, using a multiphoton excitation microscope with a resonant galvanometer, (512 × 512 pixels at 33 frames s(-1)) is described to overcome physiological motion, in vivo. The use of commercially available graphical processing units permitted the rapid 3D cross-correlation of sequential volumes to detect displacements and adjust tissue position to track motions in near real-time. Motion phantom tests maintained micron resolution with displacement velocities of up to 200 μm min(-1), well within the drift observed in many biological tissues under physiologically relevant conditions. In vivo experiments on mouse skeletal muscle using the capillary vasculature with luminal dye as a displacement reference revealed an effective and robust method of tracking tissue motion to enable (1) signal averaging over time without compromising resolution, and (2) tracking of cellular regions during a physiological perturbation.

  19. Three Dimensional Motion Tracking for High Resolution Optical Microscopy, in vivo

    PubMed Central

    Pursley, Randall; Pohida, Thomas J.; Glancy, Brian; Taylor, Joni; Chess, David; Kellman, Peter; Xue, Hui; Balaban, Robert S.

    2013-01-01

    When conducting optical imaging experiments, in vivo, the signal to noise ratio and effective spatial and temporal resolution is fundamentally limited by physiological motion of the tissue. A 3-dimensional motion tracking scheme, using a multi-photon excitation microscope with a resonant galvanometer, (512×512 pixels at 33 frames/sec) is described to overcome physiological motion, in vivo. The use of commercially available graphical processing units permitted the rapid 3-dimensional cross-correlation of sequential volumes to detect displacements and adjust tissue position to track motions in near real-time. Motion phantom tests maintained micron resolution with displacement velocities of up to 200 μm/min, well within the drift observed in many biological tissues under physiologically relevant conditions. In vivo experiments on mouse skeletal muscle using the capillary vasculature with luminal dye as a displacement reference revealed an effective and robust method of tracking tissue motion to enable (1) signal averaging over time without compromising resolution, and (2) tracking of cellular regions during a physiological perturbation. PMID:22582797

  20. High Resolution Aerosol Optical Depth Mapping of Beijing Using LANSAT8 Imagery

    NASA Astrophysics Data System (ADS)

    Li, Yan; Liu, Yuanliang; Wu, Jianliang

    2016-06-01

    Aerosol Optical Depth (AOD) is one of the most important parameters in the atmospheric correction of remote sensing images. We present a new method of per pixel AOD retrieval using the imagery of Landsat8. It is based on Second Simulation of the Satellite Signal in the Solar Spectrum (6S). General dark target method takes dense vegetation pixels as dark targets and derives their 550nm AODs directly from the LUT, and interpolates the AODs of other pixels according to spatial neighbourhood using those of dark target pixels. This method will down estimate the AOD levels for urban areas. We propose an innovative method to retrieval the AODs using multiple temporal data. For a pixel which has nothing change between the associated time, there must exists an intersection of surface albedo. When there are enough data to find the intersection it ought to be a value that meet the error tolerance. In this paper, we present an example of using three temporal Landsat ETM+ image to retrieve AOD taking Beijing as the testing area. The result is compared to the commonly employed dark target algorithm to show the effectiveness of the methods.

  1. High-resolution wind speed measurements using actively heated fiber optics

    NASA Astrophysics Data System (ADS)

    Sayde, Chadi; Thomas, Christoph K.; Wagner, James; Selker, John

    2015-11-01

    We present a novel technique to simultaneously measure wind speed (U) at thousands of locations continuously in time based on measurement of velocity-dependent heat transfer from a heated surface. Measuring temperature differences between paired passive and actively heated fiber-optic (AHFO) cables with a distributed temperature sensing system allowed estimation of U at over 2000 sections along the 230 m transect (resolution of 0.375 m and 5.5 s). The underlying concept is similar to that of a hot wire anemometer extended in space. The correlation coefficient between U measured by two colocated sonic anemometers and the AHFO were 0.91 during the day and 0.87 at night. The combination of classical passive and novel AHFO provides unprecedented dynamic observations of both air temperature and wind speed spanning 4 orders of magnitude in spatial scale (0.1-1000 m) while resolving individual turbulent motions, opening new opportunities for testing basic theories for near-surface geophysical flows.

  2. High-resolution contrast-enhanced optical coherence tomography in mice retinae

    NASA Astrophysics Data System (ADS)

    Sen, Debasish; SoRelle, Elliott D.; Liba, Orly; Dalal, Roopa; Paulus, Yannis M.; Kim, Tae-Wan; Moshfeghi, Darius M.; de la Zerda, Adam

    2016-06-01

    Optical coherence tomography (OCT) is a noninvasive interferometric imaging modality providing anatomical information at depths of millimeters and a resolution of micrometers. Conventional OCT images limit our knowledge to anatomical structures alone, without any contrast enhancement. Therefore, here we have, for the first time, optimized an OCT-based contrast-enhanced imaging system for imaging single cells and blood vessels in vivo inside the living mouse retina at subnanomolar sensitivity. We used bioconjugated gold nanorods (GNRs) as exogenous OCT contrast agents. Specifically, we used anti-mouse CD45 coated GNRs to label mouse leukocytes and mPEG-coated GNRs to determine sensitivity of GNR detection in vivo inside mice retinae. We corroborated OCT observations with hyperspectral dark-field microscopy of formalin-fixed histological sections. Our results show that mouse leukocytes that otherwise do not produce OCT contrast can be labeled with GNRs leading to significant OCT intensity equivalent to a 0.5 nM GNR solution. Furthermore, GNRs injected intravenously can be detected inside retinal blood vessels at a sensitivity of ˜0.5 nM, and GNR-labeled cells injected intravenously can be detected inside retinal capillaries by enhanced OCT contrast. We envision the unprecedented resolution and sensitivity of functionalized GNRs coupled with OCT to be adopted for longitudinal studies of retinal disorders.

  3. High Resolution Optical Spectroscopy of Rosetta Target 67P/Churyumov-Gerasimenko Using Keck HIRES

    NASA Astrophysics Data System (ADS)

    McKay, Adam; Cochran, Anita L.; Bodewits, Dennis; A'Hearn, Michael F.; Altwegg, Kathrin; Gulkis, Samuel; Snodgrass, Colin; de Val-Borro, Miguel; Kelley, Michael S.; Feaga, Lori M.; Wooden, Diane H.; Bauer, James M.; Kramer, Emily A.

    2016-10-01

    We present high spectral resolution optical spectroscopy of Rosetta target 67P/Churyumov-Gerasimenko obtained on UT Dec 26 and 27, 2015 using the HIRES instrument on Keck I when the comet was at a heliocentric distance of approximately 2 AU post-perihelion. The spectra cover a spectral range of 3500-10000 Angstroms at a spectral resolution of 67,000. These observations aim to provide high spectral resolution, large projected field of view context for the high spatial resolution and small projected field of view observations obtained from the Rosetta instrument suite. We report detections of CN, NH2, and [OI] emission. From the [OI]6300 emission we derive a water production rate of approximately 2 x 1027 mol/s. Production rates (or upper limits) for other species will be presented and placed in context with recent results from Rosetta. We will also present results pertaining to the [OI]5577 line, which combined with the [OI]6300 emission can be used as a proxy for CO2. We will compare our results to observations obtained by Rosetta as well as NEOWISE and Spitzer.

  4. High-resolution contrast-enhanced optical coherence tomography in mice retinae

    NASA Astrophysics Data System (ADS)

    Sen, Debasish; SoRelle, Elliott D.; Liba, Orly; Dalal, Roopa; Paulus, Yannis M.; Kim, Tae-Wan; Moshfeghi, Darius M.; de la Zerda, Adam

    2016-06-01

    Optical coherence tomography (OCT) is a noninvasive interferometric imaging modality providing anatomical information at depths of millimeters and a resolution of micrometers. Conventional OCT images limit our knowledge to anatomical structures alone, without any contrast enhancement. Therefore, here we have, for the first time, optimized an OCT-based contrast-enhanced imaging system for imaging single cells and blood vessels in vivo inside the living mouse retina at subnanomolar sensitivity. We used bioconjugated gold nanorods (GNRs) as exogenous OCT contrast agents. Specifically, we used anti-mouse CD45 coated GNRs to label mouse leukocytes and mPEG-coated GNRs to determine sensitivity of GNR detection in vivo inside mice retinae. We corroborated OCT observations with hyperspectral dark-field microscopy of formalin-fixed histological sections. Our results show that mouse leukocytes that otherwise do not produce OCT contrast can be labeled with GNRs leading to significant OCT intensity equivalent to a 0.5 nM GNR solution. Furthermore, GNRs injected intravenously can be detected inside retinal blood vessels at a sensitivity of ˜0.5 nM, and GNR-labeled cells injected intravenously can be detected inside retinal capillaries by enhanced OCT contrast. We envision the unprecedented resolution and sensitivity of functionalized GNRs coupled with OCT to be adopted for longitudinal studies of retinal disorders.

  5. In vivo imaging of raptor retina with ultra high resolution spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ruggeri, Marco; Major, James C., Jr.; McKeown, Craig; Wehbe, Hassan; Jiao, Shuliang; Puliafito, Carmen A.

    2008-02-01

    Among birds, raptors are well known for their exceptional eyesight, which is partly due to the unique structure of their retina. Because the raptor retina is the most advanced of any animal species, in vivo examination of its structure would be remarkable. Furthermore, a noticeable percentage of traumatic ocular injuries are identified in birds of prey presented to rehabilitation facilities. Injuries affecting the posterior segment have been considered as a major impact on raptor vision. Hence, in vivo examination of the structure of the posterior segment of the raptors would be helpful for the diagnosis of traumatized birds. The purpose of this study is to demonstrate the application of ultrahigh-resolution Spectral Domain Optical Coherence Tomography (SD-OCT) for non contact in vivo imaging of the retina of birds of prey, which to the best of our knowledge has never been attempted. For the first time we present high quality OCT images of the retina of two species of bird of prey, one diurnal hawk and one nocturnal owl.

  6. High Resolution Numerical Model of Optically Heated Float-Zone Crystal Growth with Applied Magnetic Field

    NASA Astrophysics Data System (ADS)

    Huang, Yue; Houchens, Brent

    2008-11-01

    During optically heated float-zone crystal growth processing, thermocapillary forces drive a flow in the melt. This steady, axisymmetric base flow is susceptible to instabilities, resulting in defects as the final crystal is solidified from the melt. To damp these instabilities, a magnetic field is employed. The stability of this flow, neglecting buoyancy, is studied with a full-zone model. The velocity and temperature fields are calculated by a spectral collocation method using Chebyshev polynomials as basis functions. Obtaining accurate base flows is crucial to the success of the subsequent stability analysis. A 2nd order vorticity transport representation is compared with a 4th order stream function representation. At low Hartmann numbers, the results are in good agreement. However, as resolution demands increase, the 2nd order vorticity transport formulation yields a better numerical representation by avoiding large computational errors caused by 4th and 3rd derivatives of Chebyshev terms in the 4th order stream function representation. This allows the stability analysis to be carried out at larger Hartmann numbers, where the critical thermocapillary Reynolds number is much greater.

  7. Serial endoscopy in azoxymethane treated mice using ultra-high-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Hariri, Lida P.; Qiu, Ziping; Tumlinson, Alexandre R.; Besselsen, David G.; Gerner, Eugene W.; Ignatenko, Natalia; Považay, Boris; Hermann, Boris; Sattmann, Harald; McNally, James; Unterhuber, Angelika; Drexler, Wolfgang; Barton, Jennifer K.

    2007-02-01

    Purpose: Optical coherence tomography (OCT) is a minimally invasive, depth-resolved imaging tool that can be commissioned for small diameter endoscopic applications for imaging mouse models of colorectal cancer. In this study, we utilized ultrahigh resolution OCT (UHR OCT) to serially image the lower colon of azoxymethane (AOM) treated A/J mouse models of CRC, monitor the progression of neoplastic transformations, and determine if OCT is capable of identifying early disease. Experimental Design: Thirteen AOM treated A/J and two control A/J mice were surveyed at four timepoints (8, 14, 22, and 26 weeks post AOM treatment) using a prototype 2.0 mm diameter UHR OCT endoscope-based system that achieved resolutions of 3.2 um axial and 4.4 um lateral. Histological samples were obtained at the final imaging timepoint serving as the gold standard. Results: Gross and histological assessment of the excised colonic tissue revealed at least one tumor in all 13 AOM treated mice, with most mice developing multiple tumors. In the corresponding OCT images, a progression from healthy thin mucosa to adenoma appearing as large, structurally disorganized masses was visualized over the imaging time points correlating to the locations of the grossly visualized tumors. Conclusions: This study indicates that UHR OCT enables accurate identification of disease and non-destructive visualization of CRC progression in the lower colon of mice.

  8. High-resolution imaging diagnosis of human fetal membrane by three-dimensional optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Ren, Hugang; Avila, Cecilia; Kaplan, Cynthia; Pan, Yingtian

    2011-11-01

    Microscopic chorionic pseudocyst (MCP) arising in the chorion leave of the human fetal membrane (FM) is a clinical precursor for preeclampsia which may progress to fatal medical conditions (e.g., abortion) if left untreated. To examine the utility of three-dimensional (3D) optical coherence tomography (OCT) for noninvasive delineation of the morphology of human fetal membranes and early clinical detection of MCP, 60 human FM specimens were acquired from 10 different subjects undergoing term cesarean delivery for an ex vivo feasibility study. Our results showed that OCT was able to identify the four-layer architectures of human FMs consisting of high-scattering decidua vera (DV, average thickness dDV ~ 92+/-38 μm), low-scattering chorion and trophoblast (CT, dCT ~ 150+/-67 μm), high-scattering subepithelial amnion (A, dA ~ 95+/-36 μm), and low-scattering epithelium (E, dE ~ 29+/-8 μm). Importantly, 3D OCT was able to instantaneously detect MCPs (low scattering due to edema, fluid buildup, vasodilatation) and track (staging) their thicknesses dMCP ranging from 24 to 615 μm. It was also shown that high-frequency ultrasound was able to compliment OCT for detecting more advanced thicker MCPs (e.g., dMCP>615 μm) because of its increased imaging depth.

  9. Three-dimensional motion tracking for high-resolution optical microscopy, in vivo.

    PubMed

    Bakalar, M; Schroeder, J L; Pursley, R; Pohida, T J; Glancy, B; Taylor, J; Chess, D; Kellman, P; Xue, H; Balaban, R S

    2012-06-01

    When conducting optical imaging experiments, in vivo, the signal to noise ratio and effective spatial and temporal resolution is fundamentally limited by physiological motion of the tissue. A three-dimensional (3D) motion tracking scheme, using a multiphoton excitation microscope with a resonant galvanometer, (512 × 512 pixels at 33 frames s(-1)) is described to overcome physiological motion, in vivo. The use of commercially available graphical processing units permitted the rapid 3D cross-correlation of sequential volumes to detect displacements and adjust tissue position to track motions in near real-time. Motion phantom tests maintained micron resolution with displacement velocities of up to 200 μm min(-1), well within the drift observed in many biological tissues under physiologically relevant conditions. In vivo experiments on mouse skeletal muscle using the capillary vasculature with luminal dye as a displacement reference revealed an effective and robust method of tracking tissue motion to enable (1) signal averaging over time without compromising resolution, and (2) tracking of cellular regions during a physiological perturbation. PMID:22582797

  10. Preparation of mica supported lipid bilayers for high resolution optical microscopy imaging.

    PubMed

    Matysik, Artur; Kraut, Rachel S

    2014-06-07

    Supported lipid bilayers (SLBs) are widely used as a model for studying membrane properties (phase separation, clustering, dynamics) and its interaction with other compounds, such as drugs or peptides. However SLB characteristics differ depending on the support used. Commonly used techniques for SLB imaging and measurements are single molecule fluorescence microscopy, FCS and atomic force microscopy (AFM). Because most optical imaging studies are carried out on a glass support, while AFM requires an extremely flat surface (generally mica), results from these techniques cannot be compared directly, since the charge and smoothness properties of these materials strongly influence diffusion. Unfortunately, the high level of manual dexterity required for the cutting and gluing thin slices of mica to the glass slide presents a hurdle to routine use of mica for SLB preparation. Although this would be the method of choice, such prepared mica surfaces often end up being uneven (wavy) and difficult to image, especially with small working distance, high numerical aperture lenses. Here we present a simple and reproducible method for preparing thin, flat mica surfaces for lipid vesicle deposition and SLB preparation. Additionally, our custom made chamber requires only very small volumes of vesicles for SLB formation. The overall procedure results in the efficient, simple and inexpensive production of high quality lipid bilayer surfaces that are directly comparable to those used in AFM studies.

  11. Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology in the Micro- and Nanometer Range

    NASA Astrophysics Data System (ADS)

    Huber, O.

    2009-04-01

    Focus Variation - A New Technology for High Resolution Optical 3D Surface Metrology in the Micro- and Nanometer Range S. Scherer1, E. Cristea1, O. Huber1, A. Krenn1 1 ALICONA GmbH Graz, Austria The need for increasing accuracy is a characteristic of all geo-applications, and hence of the instruments contributing to obtaining relevant data. Small and fine sensors are being developed, measuring different parameters of our geosystem and requiring continuous validation and calibration. These sensors have often very small components (fine sensors able to sense dust, atmospheric water vapour characteristics, pressure change, gravimeters, satellite micro-components), showing complex topographies including steep flanks and having varying reflective properties. In order to get valid and reliable results, quality assurance of these instruments and sensors is required. The optical technology Focus-Variation, developed by Alicona and added in the latest draft of the upcoming ISO standard 25178, provides high resolution 3D surface metrology even at those complex topographies. The technique of Focus-Variation combines the small depth of focus of an optical system with vertical scanning to provide topographical and color information from the variation of focus. It is used for high-resolution optical 3D surface measurements. The traceable and repeatable measurement results are further being used for e.g. calibration and validation purposes. Some of the characteristics of the technology are: - Measurement of instruments / samples with steep flanks up to 80° - Measurement of materials with strongly varying reflection properties - Measurement of surfaces presenting fine (from 10nm) or strong roughness Here, we present the operating principle and possible applications of the optical 3D measurement system "InfiniteFocus", which is based on the technology of Focus-Variation. With the vertical resolution of up to 10nm, InfiniteFocus yields meaningful form and roughness measurements. The

  12. Fine Particulate Matter Predictions Using High Resolution Aerosol Optical Depth (AOD) Retrievals

    NASA Technical Reports Server (NTRS)

    Chudnovsky, Alexandra A.; Koutrakis, Petros; Kloog, Itai; Melly, Steven; Nordio, Francesco; Lyapustin, Alexei; Wang, Jujie; Schwartz, Joel

    2014-01-01

    To date, spatial-temporal patterns of particulate matter (PM) within urban areas have primarily been examined using models. On the other hand, satellites extend spatial coverage but their spatial resolution is too coarse. In order to address this issue, here we report on spatial variability in PM levels derived from high 1 km resolution AOD product of Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm developed for MODIS satellite. We apply day-specific calibrations of AOD data to predict PM(sub 2.5) concentrations within the New England area of the United States. To improve the accuracy of our model, land use and meteorological variables were incorporated. We used inverse probability weighting (IPW) to account for nonrandom missingness of AOD and nested regions within days to capture spatial variation. With this approach we can control for the inherent day-to-day variability in the AOD-PM(sub 2.5) relationship, which depends on time-varying parameters such as particle optical properties, vertical and diurnal concentration profiles and ground surface reflectance among others. Out-of-sample "ten-fold" cross-validation was used to quantify the accuracy of model predictions. Our results show that the model-predicted PM(sub 2.5) mass concentrations are highly correlated with the actual observations, with out-of- sample R(sub 2) of 0.89. Furthermore, our study shows that the model captures the pollution levels along highways and many urban locations thereby extending our ability to investigate the spatial patterns of urban air quality, such as examining exposures in areas with high traffic. Our results also show high accuracy within the cities of Boston and New Haven thereby indicating that MAIAC data can be used to examine intra-urban exposure contrasts in PM(sub 2.5) levels.

  13. Fine particulate matter predictions using high resolution Aerosol Optical Depth (AOD) retrievals

    NASA Astrophysics Data System (ADS)

    Chudnovsky, Alexandra A.; Koutrakis, Petros; Kloog, Itai; Melly, Steven; Nordio, Francesco; Lyapustin, Alexei; Wang, Yujie; Schwartz, Joel

    2014-06-01

    To date, spatial-temporal patterns of particulate matter (PM) within urban areas have primarily been examined using models. On the other hand, satellites extend spatial coverage but their spatial resolution is too coarse. In order to address this issue, here we report on spatial variability in PM levels derived from high 1 km resolution AOD product of Multi-Angle Implementation of Atmospheric Correction (MAIAC) algorithm developed for MODIS satellite. We apply day-specific calibrations of AOD data to predict PM2.5 concentrations within the New England area of the United States. To improve the accuracy of our model, land use and meteorological variables were incorporated. We used inverse probability weighting (IPW) to account for nonrandom missingness of AOD and nested regions within days to capture spatial variation. With this approach we can control for the inherent day-to-day variability in the AOD-PM2.5 relationship, which depends on time-varying parameters such as particle optical properties, vertical and diurnal concentration profiles and ground surface reflectance among others. Out-of-sample “ten-fold” cross-validation was used to quantify the accuracy of model predictions. Our results show that the model-predicted PM2.5 mass concentrations are highly correlated with the actual observations, with out-of-sample R2 of 0.89. Furthermore, our study shows that the model captures the pollution levels along highways and many urban locations thereby extending our ability to investigate the spatial patterns of urban air quality, such as examining exposures in areas with high traffic. Our results also show high accuracy within the cities of Boston and New Haven thereby indicating that MAIAC data can be used to examine intra-urban exposure contrasts in PM2.5 levels.

  14. A biomarker study of high resolution sedimentary records in the eastern Mediterranean Sea since the last glacial maximum

    NASA Astrophysics Data System (ADS)

    Katsouras, G.; Gogou, A.; Bouloubassi, I.; Emeis, K.-C.; Triantaphyllou, M. V.; Lykousis, V.

    2009-04-01

    Information stored in sedimentary records provides evidence on climate and environmental variability at decadal to centennial time scales. The eastern Mediterranean Sea and the related Aegean Sea exhibit high sedimentation rates in certain areas and are considered as sensitive regions to record paleo-environmental and -climatic changes. The aim of our study is to reconstruct high-frequency paleoclimatic variations and identify associated changes in the physical, chemical and biological environment in selected basins of the eastern Mediterranean Sea, using molecular biogeochemical proxies. Here we present a high-resolution multi-proxy study along two Aegean Sea cores (north (152SL) and southeast (NS-14)) and a Libyan Sea core (HCM2/22). An important time marker and indicator of remarkable climatic and environmental changes is sapropel S1, a sediment layer rich in organic carbon. Depending on the water column depth, the sediment accumulation rates and the proximity to freshwater and water formation sources, S1 deposited between ~9.8 to 6.4 kyr BP, with an apparent interruption in the S1 deposition that occurred from ~8.6 to 7.6 kyr BP. SSTs based on alkenone unsaturation index Uḱ 37, ^15tot, ^13Corg and various marine and terrestrial biomarkers are used to investigate the region's climatic variability, and the modifications in the biogeochemical functioning of the eastern Mediterranean Sea. Uḱ 37 SST distribution in our records reveals significant fluctuations in temperature over the last 20.000 yrs. Organic carbon stable isotopes values span a narrow range over the whole sequence, with values varying to typical marine origin. The distributions of land-plant biomarkers are indicative of variable terrigenous organic matter supply and the concomitant transport of nutrients to surface waters. Furthermore, the distribution patterns and characteristic ratios of marine biomarkers exhibit differences in the paleoproductivity trends and ventilation changes over the last

  15. High Resolution, Multi-Proxy Records of Holocene Biomass Burning, Environmental Change, and Human Occupation in the Southern Maya Lowlands

    NASA Astrophysics Data System (ADS)

    Anderson, L.; Wahl, D.

    2011-12-01

    Understanding the relationship between the prehistoric Maya and their environment continues to be a primary research focus, particularly with respect to discerning the role of humans versus climate in driving environmental change. Fire was fundamental to prehistoric Maya architectural and agricultural land use practices. Burning was used to open forest for cultivation as well as for the construction of site centers and settlements. The production of lime plaster, and important building material, was dependent on significant amounts of green wood for kiln fuel. Large populations employing land use strategies dependent on burning would have put tremendous demands on forest resources. Despite the significance of fire in Maya pre-history, there has been no focused effort to produce records of biomass burning and its impacts. Here we present preliminary high-resolution fossil charcoal data that span the Holocene from a network of lacustrine and paludal sites across Peten, Guatemala. Charcoal influx data from the early to mid Holocene, prior to the arrival of sedentary agriculturalists, provides a baseline to infer natural fire regimes under specific climatic conditions, increasing our understanding of tropical fire ecology. Charcoal deposition that co-varies with evidence of agriculture and human activity can be attributed to anthropogenic burning. Results are synthesized with existing data (pollen, δ18O and δ13C, magnetic susceptibility, and physical properties) in an effort to understand the processes driving the location, timing, and extent of fires across the region. Placed in the context of changes in vegetation, sedimentation regime, and hydrology, these data provide new insight into topical fire ecology before the period of human occupation, as well as the dynamic relationship between the prehistoric Maya and their environment.

  16. High-resolution trace element records of an ice core from the eastern Tien Shan, central Asia, since 1953 AD

    NASA Astrophysics Data System (ADS)

    Liu, Yaping; Hou, Shugui; Hong, Sungmin; Hur, Soon Do; Lee, Khanghyun; Wang, Yetang

    2011-06-01

    High-resolution records of trace elements (Ba, V, Cr, Mn, Co, Ni, Cu, As, Rb, Sr, Mo, Cd, Sn, Sb, Tl, Pb, Bi, Th, and U) quantified in an ice core recovered from the Miaoergou glacier in the eastern Tien Shan, central Asia, spanning the period 1953-2004 AD, provide the first comprehensive time series on characterizing the relative contributions from natural and anthropogenic sources to the deposition of trace elements in central Asia. It is suggested that rock and soil dust is the most important natural source for most of elements investigated. Slight decreases in concentrations (or fallout fluxes) of crustal elements, such as Ba, Mn, Rb, Th, U, and Sr are observed during recent decades, which may be due to decreases in dust emissions from source regions and a decrease of accumulation rate since 1980s. The increasing trends of median concentrations and crustal enrichment factors (EFc) of V, Cr, Co, Ni, Cu, and Mo, during the period 1953-2004 AD, are insignificant in comparison to their respective levels prior to 1953 AD. However, slight enhancements of both concentrations and EFc are observed for Cd, Sb, Pb, Bi, Tl, and Sn since 1950s. Such recent increases are likely to be attributed to enhanced anthropogenic emissions, such as metal smelting, mining, stationary fossil fuel combustion, and combustion of gasoline due to human activities in Eurasia, particularly Xinjiang in northwestern China, Russia, and Kazakhstan. Our study supports evidence that environmental contamination has become a global problem for Pb and Bi and a large-scale phenomenon for Cd, Sb, Tl, and Sn.

  17. High-resolution trace element records of an ice core from the eastern Tien Shan, central Asia, since 1953 AD

    NASA Astrophysics Data System (ADS)

    Yaping, L.; Shugui, H.; Hong, S.; Hur, S.; Khanghyun, L.; Yetang, W.

    2011-12-01

    High-resolution records of trace elements (Ba, V, Cr, Mn, Co, Ni, Cu, As, Rb, Sr, Mo, Cd, Sn, Sb, Tl, Pb, Bi, Th and U) quantified in an ice core recovered from the Miaoergou glacier in the eastern Tien Shan, central Asia, spanning the period 1953-2004 AD, provide the first comprehensive time-series on characterizing the relative contributions from natural and anthropogenic sources to the deposition of trace elements in central Asia. It is suggested that rock and soil dust is the most important natural source for most of elements investigated. Slight decreases in concentrations (or fallout fluxes) of crustal elements, such as Ba, Mn, Rb, Th, U and Sr are observed during recent decades, which may be due to decreases in dust emissions from source regions and a decrease of accumulation rate since 1980s. The increasing trends of median concentrations and crustal enrichment factors (EFc) of V, Cr, Co, Ni, Cu, and Mo, during the period 1953-2004 AD, are insignificant in comparison to their respective levels prior to 1953 AD. However, slight enhancements of both concentrations and EFc are observed for Cd, Sb, Pb, Bi, Tl and Sn since 1950s. Such recent increases are likely to be attributed to enhanced anthropogenic emissions, such as metal smelting, mining, stationary fossil fuel combustion and combustion of gasoline due to human activities in Eurasia, particularly Xinjiang in northwestern China, Russia and Kazakhstan. Our study supports evidence that environmental contamination has become a global problem for Pb and Bi and a large scale phenomenon for Cd, Sb, Tl, and Sn.

  18. Early to Middle Jurassic palaeoenvironmental changes: High resolution δ13C and δ18O records from the UK

    NASA Astrophysics Data System (ADS)

    Korte, C.; Hesselbo, S.; Ullmann, C. V.; Ruhl, M.; Thibault, N.

    2013-12-01

    Low-Mg-calcite fossils, such as bivalves, belemnites and brachiopods, and bulk rocks have been extensively utilized to reconstruct past seawater chemistry and paleoenviron¬mental changes. Recent work on major bioevents demonstrated that particularly higher resolution stable isotope records are necessary to reveal short-term paleoenviron¬mental fluctuations and, in addition, to discover its causes. Here we present a new high resolution carbon and oxygen isotope dataset generated from low-Mg-calcite fossils, fossil wood and bulk rocks collected from Early to Middle Jurassic marine successions of the UK. In addition to the well know carbon isotope fluctuations across the Toarcian Oceanic Anoxic Event (OAE), further δ13C perturbations have been obtained from the analyzed samples: (1) a positive trend in the earliest Sinemurian (Conybeari zone), negative excursions in the (2) Sinemurian Bucklandi zone and (3) at the Sinemurian-Pliensbachian boundary (upper raricostatum and lower jamesoni zones), and (4) a positive excursion in the Late Pliensbachian margaritatus zone. At the Sinemurian-Pliensbachian boundary a positive δ18O shift occurs during the negative δ13C excursion, suggesting most likely bottom water cooling as a result of the Early Pliensbachian transgression. Two additional cooling events, (1) in the Late Pliensbachian and (2) during the Aalenian-Bajocian, are discovered by positive oxygen isotope trends. The cool Late Pliensbachian shallow sea-floor is in agreement with previous inference of partial icehouse conditions at that time. More uncertain are potential icehouse interludes during the Aalenian-Bajocian interval. The new isotope datasets show partly a strong similarity between the positions of the global warming/cooling events within transgressive/regressive phases of second-order depositional sequences though the Early to Middle Juras¬sic supporting the idea that second-order depositional se¬quences are a result of eustatic sea-level changes at

  19. Sentinel-2 Optical High Resolution Mission for GMES Land Operational Services

    NASA Astrophysics Data System (ADS)

    Drusch, M.; Gascon, F.; Martimort, P.; Spoto, F.

    2009-12-01

    In the framework of the Global Monitoring for Environment and Security (GMES) programme, the European Space Agency (ESA) in partnership with the European Commission (EC) is developing the Sentinel-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a twin satellites configuration deployed in polar sun-synchronous orbit and designed to offer a unique combination of systematic global coverage, high revisit (five days at equator with two satellites) and high spatial resolution imagery (10/20/60m). The Multispectral instrument features 13 spectral bands, going from visible to short wave infrared domains. The instrument is designed to provide in orbit calibration, excellent radiometric and geometric performance, and with a capability to support accurate image geolocation and co-registration. The Sentinel-2 mission is more particularly tailored to the monitoring of land terrains, including vegetation and urban areas. Sentinel-2 will ensure data continuity with the SPOT and Landsat multi-spectral sensors, while accounting for future service evolution. The lifetime of each Sentinel-2 spacecraft is specified as 7 years and propellant is sized for 12 years, including provision for de-orbiting manoeuvres at end-of-life. The satellite will be three-axis stabilized with an AOCS based on high-rate multi-head star trackers, mounted on the instrument structure for better pointing accuracy and stability, as well as a laser gyroscope and a dual-frequency GNSS receiver. The Multi-Spectral Instrument (MSI) is based on the pushbroom concept. It features a Three Mirror Anastigmat (TMA) telescope with a pupil diameter of about 150 mm, and achieves a very good imaging quality all across its wide Field of View (290 km swath width, significantly enlarged with respect to Landsat and SPOT). The telescope structure and the mirrors are made of silicon carbide for minimizing thermo-elastic deformations. The visible and

  20. A high-resolution record of Southern Ocean intermediate water radiocarbon over the past 30,000 years

    NASA Astrophysics Data System (ADS)

    Hines, Sophia K. V.; Southon, John R.; Adkins, Jess F.

    2015-12-01

    The circulation of intermediate waters plays an important role in global heat and carbon transport in the ocean and changes in their distribution are closely tied to glacial-interglacial climate change. Coupled radiocarbon and U/Th measurements on deep-sea Desmophyllum dianthus corals allow for the reconstruction of past intermediate water ventilation. We present a high-resolution time series of Antarctic Intermediate Water radiocarbon from 44 corals spanning 30 ka through the start of the Holocene, encompassing the transition into the Last Glacial Maximum (LGM) and the last deglaciation. Corals were collected south of Tasmania from water depths between 1430 and 1950 m with 80% of them between 1500 and 1700 m, giving us a continuous record from a narrow depth range. The record shows three distinct periods of circulation: the MIS 3-2 transition, the LGM/Heinrich Stadial 1 (extending from ∼22 to 16 kyr BP), and the Antarctic Cold Reversal (ACR). The MIS 3-2 transition and the ACR are characterized by abrupt changes in intermediate water radiocarbon while the LGM time period generally follows the atmosphere at a constant offset, in support of the idea that the LGM ocean was at steady state for its 14C distribution. Closer inspection of the LGM time period reveals a 40‰ jump at ∼19 ka from an atmospheric offset of roughly 230‰ to 190‰, coincident with an observed 10-15 m rise in sea level and a southward shift of the Subantarctic and Polar Fronts, an abrupt change not seen in deeper records. During the ACR time period intermediate water radiocarbon is on average less offset from the atmosphere (∼ 110 ‰) and much more variable. This variability has been captured within the lifetimes of three individual corals with changes of up to 35‰ over ∼40 yr, likely caused by the movement of Southern Ocean fronts. This surprising result of relatively young and variable intermediate water radiocarbon during the ACR seems to go against the canonical idea of reduced

  1. A New High-Resolution Record of Benthic and Planktonic Foraminiferal Stable Isotopes from the Bermuda Rise

    NASA Astrophysics Data System (ADS)

    Curry, W. B.; Keigwin, L. D.

    2011-12-01

    A new core from Bermuda Rise (KNR191-1-19CDH, 33° 41.194' N, 57° 36.907' W, 4579 meters) recovered 38 m of sediment spanning the last 160,000 years. We have now completed initial high-resolution records of planktonic (G. ruber, 212-250μm) and benthic (C. wuellerstorfi, C. sp., and N. umbonifera, for the most part) foraminiferal stable isotopes for the last deglaciation using samples spaced every centimeter, providing a median sample spacing of about 110 to 130 years. Because of the high and variable sedimentation rates, the foraminifera are not always present in each sample so the mean sample spacing in each time series is a bit higher. The age model for this core is based on many new AMS 14C dates on G. inflata, and additional age control provided by correlation to other well-dated cores nearby. The records are higher resolution reproductions of several previous studies, all accomplished on different Bermuda Rise sediment cores. The G. ruber δ18O record exhibits a three-stage decrease during the deglaciation. An initial decrease of about 1% occurs at 16.5 ka and is followed by a return to near glacial values by 15.5 ka. The next decrease of about 1.5% begins at about 14.6 ka and is nearly synchronous with the Bolling-Allerod warming observed in the Greenland ice cores. A Younger Dryas cooling, observed as a 0.5% increase in δ18O, is followed by a warming into the early Holocene where oxygen isotope values are about 2% lower than glacial maximum values. The benthic foraminiferal carbon isotope record is unprecendented in its detail for Bermuda Rise cores. Last glacial maximum values are variable but average about -0.5% (VPDB). There is an increase to higher values at about 16.5 ka - synchronous with the first decrease in G. ruber δ18O - and a return to very low values (-0.7 to -0.8% VPDB) by about 15.5 ka. The record exhibits an abrupt 1% increase in δ13C beginning at about 14.4 ka, followed by a 0.5% decrease during the Younger Dryas. Maximum values occur

  2. IMAPS - A high-resolution, echelle spectrograph to record far-ultraviolet spectra of stars from sounding rockets

    NASA Technical Reports Server (NTRS)

    Jenkins, E. B.; Joseph, C. L.; Long, D.; Zucchino, P. M.; Carruthers, G. R.

    1988-01-01

    A novel sounding rocket payload consisting of a slitless objective grating spectrograph with no transmission elements in the optical train (or detector) is described. This instrument, called the interstellar medium absorption profile spectrograph (IMAPS), is designed to provide continuous coverage over the wavelength range of 950-1150 A; it has an effective collecting area of about 4 sq cm and can record spectra of pointlike sources at a wavelength resolution of 0.004 A and with a sample interval of 0.002 A. The successful use of this instrument aboard a Black Brant rocket is described.

  3. Iterative re-weighted approach to high-resolution optical coherence tomography with narrow-band sources.

    PubMed

    Mousavi, Mahta; Duan, Lian; Javidi, Tara; Ellerbee Bowden, Audrey K

    2016-01-25

    Optical coherence tomography (OCT) is a non-invasive optical imaging modality capable of high resolution imaging of internal tissue structures. It is widely believed that the high axial resolution in OCT systems requires a wide-bandwidth light source. As a result, often the potential advantages of narrow-bandwidth sources (in terms of cost and/or imaging speed) are understood to come at the cost of significant reduction in imaging resolution. In this paper, we argue that this trade-off between resolution and speed is a shortcoming imposed by the-state-of-the-art A-scan reconstruction algorithm, Fast Fourier Transform, and can be circumvented through use of alternative processing methods. In particular, we investigate the shortcomings of the FFT as well as previously proposed alternatives and demonstrate the first application of an iterative regularized re-weighted l(2) norm method to improve the axial resolution of fast scan rate OCT systems in the narrow-bandwidth imaging conditions. We validate our claims via experimental results generated from a home-built OCT system used to image layered phantom and in vivo data. Our results rely on new, sophisticated signal processing algorithms to generate higher precision (i.e., higher resolution) OCT images at correspondingly fast scan rates. In other words, our work demonstrates the feasibility of simultaneously more reliable and more comfortable medical imaging systems for patients by reducing the overall scan time, without sacrificing image quality. PMID:26832556

  4. High-Resolution Imaging by Adaptive Optics Scanning Laser Ophthalmoscopy Reveals Two Morphologically Distinct Types of Retinal Hard Exudates.

    PubMed

    Yamaguchi, Muneo; Nakao, Shintaro; Kaizu, Yoshihiro; Kobayashi, Yoshiyuki; Nakama, Takahito; Arima, Mitsuru; Yoshida, Shigeo; Oshima, Yuji; Takeda, Atsunobu; Ikeda, Yasuhiro; Mukai, Shizuo; Ishibashi, Tatsuro; Sonoda, Koh-Hei

    2016-01-01

    Histological studies from autopsy specimens have characterized hard exudates as a composition of lipid-laden macrophages or noncellular materials including lipid and proteinaceous substances (hyaline substances). However, the characteristics of hard exudates in living patients have not been examined due to insufficient resolution of existing equipment. In this study, we used adaptive optics scanning laser ophthalmoscopy (AO-SLO) to examine the characteristics of hard exudates in patients with retinal vascular diseases. High resolution imaging using AO-SLO enables morphological classification of retinal hard exudates into two types, which could not be distinguished either on fundus examination or by spectral domain optical coherence tomography (SD-OCT). One, termed a round type, consisted of an accumulation of spherical particles (average diameter of particles: 26.9 ± 4.4 μm). The other, termed an irregular type, comprised an irregularly shaped hyper-reflective deposition. The retinal thickness in regions with round hard exudates was significantly greater than the thickness in regions with irregular hard exudates (P = 0.01 →0.02). This differentiation of retinal hard exudates in patients by AO-SLO may help in understanding the pathogenesis and clinical prognosis of retinal vascular diseases. PMID:27641223

  5. High-resolution and fast-response fiber-optic temperature sensor using silicon Fabry-Pérot cavity.

    PubMed

    Liu, Guigen; Han, Ming; Hou, Weilin

    2015-03-23

    We report a fiber-optic sensor based on a silicon Fabry-Pérot cavity, fabricated by attaching a silicon pillar on the tip of a single-mode fiber, for high-resolution and high-speed temperature measurement. The large thermo-optic coefficient and thermal expansion coefficient of the silicon material give rise to an experimental sensitivity of 84.6 pm/°C. The excellent transparency and large refractive index of silicon over the infrared wavelength range result in a visibility of 33 dB for the reflection spectrum. A novel average wavelength tracking method has been proposed and demonstrated for sensor demodulation with improved signal-to-noise ratio, which leads to a temperature resolution of 6 × 10⁻⁴ °C. Due to the high thermal diffusivity of silicon, a response time as short as 0.51 ms for a sensor with an 80-µm-diameter and 200-µm-long silicon pillar has been experimentally achieved, suggesting a maximum frequency of ~2 kHz can be reached, to address the needs for highly dynamic environmental variations such as those found in the ocean. PMID:25837068

  6. High-Resolution Imaging by Adaptive Optics Scanning Laser Ophthalmoscopy Reveals Two Morphologically Distinct Types of Retinal Hard Exudates

    PubMed Central

    Yamaguchi, Muneo; Nakao, Shintaro; Kaizu, Yoshihiro; Kobayashi, Yoshiyuki; Nakama, Takahito; Arima, Mitsuru; Yoshida, Shigeo; Oshima, Yuji; Takeda, Atsunobu; Ikeda, Yasuhiro; Mukai, Shizuo; Ishibashi, Tatsuro; Sonoda, Koh-hei

    2016-01-01

    Histological studies from autopsy specimens have characterized hard exudates as a composition of lipid-laden macrophages or noncellular materials including lipid and proteinaceous substances (hyaline substances). However, the characteristics of hard exudates in living patients have not been examined due to insufficient resolution of existing equipment. In this study, we used adaptive optics scanning laser ophthalmoscopy (AO-SLO) to examine the characteristics of hard exudates in patients with retinal vascular diseases. High resolution imaging using AO-SLO enables morphological classification of retinal hard exudates into two types, which could not be distinguished either on fundus examination or by spectral domain optical coherence tomography (SD-OCT). One, termed a round type, consisted of an accumulation of spherical particles (average diameter of particles: 26.9 ± 4.4 μm). The other, termed an irregular type, comprised an irregularly shaped hyper-reflective deposition. The retinal thickness in regions with round hard exudates was significantly greater than the thickness in regions with irregular hard exudates (P = 0.01 →0.02). This differentiation of retinal hard exudates in patients by AO-SLO may help in understanding the pathogenesis and clinical prognosis of retinal vascular diseases. PMID:27641223

  7. A high resolution electro-optical approach for investigating transition of soluble proteins to integral membrane proteins probed by colicin A.

    PubMed

    Honigmann, Alf; Pulagam, Lakshmi Padmavathi; Sippach, Michael; Bartsch, Philipp; Steinhoff, Heinz-Jürgen; Wagner, Richard

    2012-10-19

    The transition from water soluble state to an integral membrane protein state is a crucial step in the formation of the active form of many pore-forming or receptor proteins. Albeit this, high resolution techniques which allow assay of protein membrane binding and concomitant development of the final active form in the membrane await further development. Here, we describe a horizontal artificial bilayers setup allowing for simultaneous electrical and optical measurements at a single molecule level. We use the membrane binding and subsequent channel formation of colicin A (ColA) a water soluble bacteriocin secreted by some strains of Escherichia coli to demonstrate the potential of the combined electro-optical technique. Our results expand the knowledge on ColA molecular details which show that active ColA is monomeric; membrane binding is pH but not membrane-potential (Δϕ) dependent. ColA is at Δϕ=0 permeable for molecules ≥1 nm. Although ColA exhibits low ion conductance it facilitates permeation of large molecules. Our electro-optical recordings reveal ColA monomeric state and the chimeric character of its pore. PMID:23000162

  8. Detection and spatiotemporal analysis of methane ebullition on thermokarst lake ice using high-resolution optical aerial imagery

    NASA Astrophysics Data System (ADS)

    Lindgren, P. R.; Grosse, G.; Anthony, K. M. Walter; Meyer, F. J.

    2016-01-01

    Thermokarst lakes are important emitters of methane, a potent greenhouse gas. However, accurate estimation of methane flux from thermokarst lakes is difficult due to their remoteness and observational challenges associated with the heterogeneous nature of ebullition. We used high-resolution (9-11 cm) snow-free aerial images of an interior Alaskan thermokarst lake acquired 2 and 4 days following freeze-up in 2011 and 2012, respectively, to detect and characterize methane ebullition seeps and to estimate whole-lake ebullition. Bubbles impeded by the lake ice sheet form distinct white patches as a function of bubbling when lake ice grows downward and around them, trapping the gas in the ice. Our aerial imagery thus captured a snapshot of bubbles trapped in lake ice during the ebullition events that occurred before the image acquisition. Image analysis showed that low-flux A- and B-type seeps are associated with low brightness patches and are statistically distinct from high-flux C-type and hotspot seeps associated with high brightness patches. Mean whole-lake ebullition based on optical image analysis in combination with bubble-trap flux measurements was estimated to be 174 ± 28 and 216 ± 33 mL gas m-2 d-1 for the years 2011 and 2012, respectively. A large number of seeps demonstrated spatiotemporal stability over our 2-year study period. A strong inverse exponential relationship (R2 > = 0.79) was found between the percent of the surface area of lake ice covered with bubble patches and distance from the active thermokarst lake margin. Even though the narrow timing of optical image acquisition is a critical factor, with respect to both atmospheric pressure changes and snow/no-snow conditions during early lake freeze-up, our study shows that optical remote sensing is a powerful tool to map ebullition seeps on lake ice, to identify their relative strength of ebullition, and to assess their spatiotemporal variability.

  9. Enhancing sensitivity of high resolution optical coherence tomography using an optional spectrally encoded extended source (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yu, Xiaojun; Liu, Xinyu; Chen, Si; Wang, Xianghong; Liu, Linbo

    2016-03-01

    High-resolution optical coherence tomography (OCT) is of critical importance to disease diagnosis because it is capable of providing detailed microstructural information of the biological tissues. However, a compromise usually has to be made between its spatial resolutions and sensitivity due to the suboptimal spectral response of the system components, such as the linear camera, the dispersion grating, and the focusing lenses, etc. In this study, we demonstrate an OCT system that achieves both high spatial resolutions and enhanced sensitivity through utilizing a spectrally encoded source. The system achieves a lateral resolution of 3.1 μm and an axial resolution of 2.3 μm in air; when with a simple dispersive prism placed in the infinity space of the sample arm optics, the illumination beam on the sample is transformed into a line source with a visual angle of 10.3 mrad. Such an extended source technique allows a ~4 times larger maximum permissible exposure (MPE) than its point source counterpart, which thus improves the system sensitivity by ~6dB. In addition, the dispersive prism can be conveniently switched to a reflector. Such flexibility helps increase the penetration depth of the system without increasing the complexity of the current point source devices. We conducted experiments to characterize the system's imaging capability using the human fingertip in vivo and the swine eye optic never disc ex vivo. The higher penetration depth of such a system over the conventional point source OCT system is also demonstrated in these two tissues.

  10. High-resolution Record of Holocene Climate, Vegetation, and Fire from a Raised Peat Bog, Prince Edward Island, Canadian Maritimes

    NASA Astrophysics Data System (ADS)

    Peros, M. C.; Chan, K.; Ponsford, L.; Carroll, J.; Magnan, G.

    2014-12-01

    Raised peat bogs receive all precipitation and nutrients from the atmosphere and are thus widely used archives for information on past environments and climates. In this paper we provide high-resolution multi-proxy data from a raised bog from northeastern Prince Edward Island, located in the Gulf of St. Lawrence, Canada. We studied testate amoeba (a proxy for water table depth), macrocharcoal (a proxy for local-scale fire), peat humification (a proxy for decomposition), plant macrofossils (indicative of local-scale vegetation), and organic matter content (yielding carbon accumulation rates) from a 5.5 m long core lifted from the center of Baltic Bog. Eleven AMS radiocarbon dates show that peat accumulation began before 9000 cal yr BP and continued almost uninterrupted until the present. The macrofossil data show that a transition from a sedge-dominated fen to a sphagnum-dominated bog occurred around 8000 cal yr BP, and sphagnum remained dominant in the bog throughout most of the Holocene. A testate amoeba-based reconstruction of water table depth indicates that conditions were drier during the early Holocene (~8000 to 5000 cal yr BP) and became gradually wetter into the late Holocene. In addition, a number of higher frequency shifts in precipitation are inferred throughout the Holocene on the basis of the testate amoeba and humification results. The macrocharcoal evidence indicates fire—probably in the surrounding forest—was relatively more common during the early Holocene, perhaps due to drier climate conditions. A large influx of charcoal at around 2000 cal yr BP suggests the presence of one or more major fires at this time, and a concurrent decrease in the rate of peat accumulation indicates the fire may have affected the bog itself. The data from Baltic Bog is broadly comparable to other proxy data (in particular pollen studies) from the Canadian Maritimes. This work is important because it: 1) helps us better understand the role of hydroclimatic

  11. High-resolution authigenic 10Be/9Be records : A proxy indicator of the past geomagnetic field variability

    NASA Astrophysics Data System (ADS)

    Carcaillet, J.; Thouveny, N.; Bourlès, D. L.

    2003-04-01

    At global scale, the synchronicity of abnormal directions of the paleomagnetic field and minimum intensities supports the hypothesis of a relationship between the occurrence of excursions and/or polarity changes and the collapse of the dipolar component. We present quantitative evaluations of relationships between 10Be production rate variations and geomagnetic events using high resolution authigenic 10Be/9Be ratios and continuous paleointensity records measured in three marine sediment sequences located on the Portuguese margin, (MD95-2042 and MD95-2040), and in the Western Pacific, (MD97-2140). Since 10Be concentrations measured in marine sediments not only depend on 10Be production rates but also on oceanic and sedimentary effects, authigenic (i.e. adsorbed onto particles from the water column) 10Be concentrations were normalized to their related authigenic 9Be concentrations in order to account for these disturbing effects on the sedimentation rate as well as on the chemical and granulometric composition of the sediments. Due to their different sources, only the soluble form of both beryllium isotopes may indeed have been homogenized in the water column before deposition in the sediment. The measured 10Be/9Be ratios increase significantly at all identified excursions and reversals, associated with decreased paleointensities, consistently with the expected relationship between magnetic moment and cosmic ray flux (Q/Qo=(M/Mo)-1/2). Our results confirm the global occurrence of well-recognized and well-dated phases of low geomagnetic moments associated to well known geomagnetic excursions, short events or polarity reversals that occurred between 0 and 300 ka BP and between 0.6 and 1.3 Ma BP: the Laschamp excursion, the Blake event, the Jamaica/Pringle falls excursion, the Brunhes-Matuyama Reversal, the upper and lower Jaramillo transitions and the Cobb Mountain event. They strengthen the validity of recently reported excursions: Icelandic basin, Calabrian Ridge 0

  12. On-Orbit Geometric Calibration Approach for High-Resolution Geostationary Optical Satellite GaoFen-4

    NASA Astrophysics Data System (ADS)

    Wang, Mi; Cheng, Yufeng; Long, Xiaoxiang; Yang, Bo

    2016-06-01

    The GaoFen-4 (GF-4) remote sensing satellite is China's first civilian high-resolution geostationary optical satellite, which has been launched at the end of December 2015. To guarantee the geometric quality of imagery, this paper presents an on-orbit geometric calibration method for the area-array camera of GF-4. Firstly, we introduce the imaging features of area-array camera of GF-4 and construct a rigorous imaging model based on the analysis of the major error sources from three aspects: attitude measurement error, orbit measurement error and camera distortion. Secondly, we construct an on-orbit geometric calibration model by selecting and optimizing parameters of the rigorous geometric imaging model. On this basis, the calibration parameters are divided into two groups: external and internal calibration parameters. The external parameters are installation angles between the area-array camera and the star tracker, and we propose a two-dimensional direction angle model as internal parameters to describe the distortion of the areaarray camera. Thirdly, we propose a stepwise parameters estimation method that external parameters are estimated firstly, then internal parameters are estimated based on the generalized camera frame determined by external parameters. Experiments based on the real data of GF-4 shows that after on-orbit geometric calibration, the geometric accuracy of the images without ground control points is significantly improved.

  13. HIGH-RESOLUTION OPTICAL SPECTROSCOPY OF DY Cen: DIFFUSE INTERSTELLAR BANDS IN A PROTO-FULLERENE CIRCUMSTELLAR ENVIRONMENT?

    SciTech Connect

    Garcia-Hernandez, D. A.; Lambert, David L. E-mail: nkrao@iiap.res.in

    2012-11-01

    We search high-resolution and high-quality VLT/UVES optical spectra of the hot R Coronae Borealis star DY Cen for electronic transitions of the C{sub 60} molecule and diffuse interstellar bands (DIBs). We report the non-detection of the strongest C{sub 60} electronic transitions (e.g., those at {approx}3760, 3980, and 4024 A). The absence of C{sub 60} absorption bands may support recent laboratory results, which show that the {approx}7.0, 8.5, 17.4, and 18.8 {mu}m emission features seen in DY Cen-and other similar objects with polycyclic-aromatic-hydrocarbon-like dominated IR spectra-are attributable to proto-fullerenes or fullerene precursors rather than to C{sub 60}. DIBs toward DY Cen are normal for its reddening; the only exception is the DIB at 6284 A (possibly also the 7223 A DIB) which is found to be unusually strong. We also report the detection of a new broad (FWHM {approx} 2 A) and unidentified feature centered at {approx}4000 A. We suggest that this new band may be related to the circumstellar proto-fullerenes seen at infrared wavelengths.

  14. Direct visualization of tear film on soft contact lens using ultra-high resolution spectral domain optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Wang, Jianhua; Jiao, Shuliang; Ruggeri, Marco; Wehbe, Hassan M.

    2008-02-01

    The integrity of the tear film on the surface of contact lenses is essential to maintaining visual clarity and the overall health of the superficial structures of the eye (cornea and conjunctiva) for contact lens wearers. It is very critical to evaluate pre- and post-lens tear films in contact lens practice to make sure the lens is properly fitted. Improper lens fitting may cause ocular discomfort, visual distortion and ocular infection. It is very often for soft contact lens wearers to experience dry eye, especially in the afternoon after wearing the lens for a period of time. Dry eye has been a common cause of contact lens drop-off. There is currently no method available to directly visualize the tears on and underneath the contact lens in situ on human eye, mainly due to the extremely difficulty in imaging the micrometer-thin tear layer. An ultra-high resolution spectral domain optical coherence tomography has been developed with a telecentric light delivery system mounted with a slit-lamp. The system has a 3 micrometer depth resolution with a scan width up to 15 mm. The system was used to image soft contact lenses on the human eye. For the first time to our knowledge, tear films on the center and edge of the soft contact lens were directly visualized in vivo.

  15. Zero-crossing approach to high-resolution reconstruction in frequency-domain optical-coherence tomography.

    PubMed

    Krishnan, Sunder Ram; Seelamantula, Chandra Sekhar; Bouwens, Arno; Leutenegger, Marcel; Lasser, Theo

    2012-10-01

    We address the problem of high-resolution reconstruction in frequency-domain optical-coherence tomography (FDOCT). The traditional method employed uses the inverse discrete Fourier transform, which is limited in resolution due to the Heisenberg uncertainty principle. We propose a reconstruction technique based on zero-crossing (ZC) interval analysis. The motivation for our approach lies in the observation that, for a multilayered specimen, the backscattered signal may be expressed as a sum of sinusoids, and each sinusoid manifests as a peak in the FDOCT reconstruction. The successive ZC intervals of a sinusoid exhibit high consistency, with the intervals being inversely related to the frequency of the sinusoid. The statistics of the ZC intervals are used for detecting the frequencies present in the input signal. The noise robustness of the proposed technique is improved by using a cosine-modulated filter bank for separating the input into different frequency bands, and the ZC analysis is carried out on each band separately. The design of the filter bank requires the design of a prototype, which we accomplish using a Kaiser window approach. We show that the proposed method gives good results on synthesized and experimental data. The resolution is enhanced, and noise robustness is higher compared with the standard Fourier reconstruction. PMID:23201655

  16. Functional optical coherence tomography for high-resolution mapping of cilia beat frequency in the mouse oviduct in vivo

    NASA Astrophysics Data System (ADS)

    Wang, Shang; Burton, Jason C.; Behringer, Richard R.; Larina, Irina V.

    2016-02-01

    Since mouse is a superior model for genetic analysis of human disorders, reproductive studies in mice have significant implications on further understanding of fertility and infertility in humans. Fertilized oocytes are transported through the reproductive tract by motile cilia lining the lumen of the oviduct as well as by oviduct contractions. While the role of cilia is well recognized, ciliary dynamics in the oviduct is not well understood, largely owing to the lack of live imaging approaches. Here, we report in vivo micro-scale mapping of cilia and cilia beat frequency (CBF) in the mouse oviduct using optical coherence tomography (OCT). This functional imaging method is based on spectral analysis of the OCT speckle variations produced by the beat of cilia in the oviduct, which does not require exogenous contrast agents. Animal procedures similar to the ones used for production of transgenic mice are utilized to expose the reproductive organs for imaging in anesthetized females. In this paper, we first present in vivo structural imaging of the mouse oviduct capturing the oocyte and the preimplantation embryo and then show the result of depth-resolved high-resolution CBF mapping in the ampulla of the live mouse. These data indicate that this structural and functional OCT imaging approach can be a useful tool for a variety of live investigations of mammalian reproduction and infertility.

  17. High resolution archives from the Black Sea and Caspian Sea as records of hydrological changes during the Holocene

    NASA Astrophysics Data System (ADS)

    Marret, F.; Mudie, P.; Leroy, S.; Aksu, A.; Hiscott, R.

    2009-04-01

    Studies of multiple proxies from sediments of marginal seas, such as the Black Sea, or epicontinental seas, such as the Caspian Sea, have demonstrated their great potential to document past changes in climate and hydrological cycles. Over the last decade, the Black Sea has been the centre of focus with regards to the timing, speed and extent of its reconnection with the Mediterranean Sea at the beginning of the Holocene; this has led to controversial debate in the scientific community and world-wide public interest. Notably, it has been suggested that the speed of this catastrophic flooding event led to the dispersal of Neolithic populations living on the northern shore of the Black Sea. The evidence for this abrupt flooding hypothesis included geophysical surveys, sedimentological and geochemical studies on the western and northern shelves. Although the interpretation of these data may be equivocal, it appears that a major environmental change occurred at around 8.5 ka BP as evidenced by a number of proxies (1). The Caspian Sea has revealed significant information with regards to modern marine proxies that were previously identified in early Holocene Black Sea sediments. Their modern distribution in the Caspian Sea has allowed to better constraint the paleoconditions of the Black Sea before its reconnection with the Mediterranean Sea at the beginning of the Holocene (2). Further studies of late Holocene Caspian Sea sediments have highlighted changes in salinity due to modification in river flows and climate change (3). We present here evidence for the gradual pace of this transformation of the Black Sea, from a brackish lake to its present-day marine conditions, based on a high resolution record of dinoflagellate cysts that are used to reconstruct past sea-surface conditions. Most previous Black Sea dinocyst studies were conducted at a low resolution, on the order of millennia, whereas our new record has a multi-decadal resolution. This has enabled us to pinpoint

  18. High-resolution optical spectroscopy of the yellow hypergiant V1302 Aql (=IRC+10420) in 2001-2014

    NASA Astrophysics Data System (ADS)

    Klochkova, V. G.; Chentsov, E. L.; Miroshnichenko, A. S.; Panchuk, V. E.; Yushkin, M. V.

    2016-07-01

    We present the results of a study of spectral features and the velocity field in the atmosphere and circumstellar envelope of the yellow hypergiant V1302 Aql, the optical counterpart of the IR source IRC+10420, based on high-resolution optical spectroscopic observations in 2001-2014. We measured heliocentric radial velocities of the following types of lines: forbidden and permitted pure emission, absorption and emission components of lines of ions, pure absorption (e.g. He I, Si II) and interstellar components of the Na I D lines, K I and diffuse interstellar bands (DIBs). Pure absorption and forbidden and permitted pure emission, which have heliocentric radial velocities Vr = 63.7 ± 0.3, 65.2 ± 0.3 and 62.0 ± 0.4 km s-1, respectively, are slightly redshifted relative to the systemic radial velocity (Vsys ˜ 60 km s-1). The positions of the absorption components of the lines with inverse P Cyg profiles are redshifted by ˜20 km s-1, suggesting that clumps falling on to the star have been stable over all observing dates. The average heliocentric radial velocity of the DIBs is Vr(DIB) = 4.6 ± 0.2 km s-1. A Hα line profile with the red peak slightly stronger than the blue one was observed only once, on 2007 November 24. Comparison of pure absorption lines observed in 2001-2014 with those in earlier data does not show noticeable variations. The kinematic picture in the atmosphere was stable for observations during 2001-2014. Our results as a whole let us conclude that the hypergiant has reached a phase of slowing down (or termination) of effective temperature growth and is currently located near the high-temperature boundary of the Yellow Void in the Hertszprung-Russell diagram.

  19. Vertical and Horizontal Corneal Epithelial Thickness Profile Using Ultra-High Resolution and Long Scan Depth Optical Coherence Tomography

    PubMed Central

    Jiang, Hong; Xu, Zhe; Perez, Victor; Wang, Jianhua

    2014-01-01

    Purpose To determine the vertical and horizontal thickness profiles of the corneal epithelium in vivo using ultra-long scan depth and ultra-high resolution spectral domain optical coherence tomography (SD-OCT). Methods A SD-OCT was developed with an axial resolution of ∼3.3 µm in tissue and an extended scan depth. Forty-two eyes of 21 subjects were imaged twice. The entire horizontal and vertical corneal epithelial thickness profiles were evaluated. The coefficient of repeatability (CoR) and intraclass correlation (ICC) of the tests and interobserver variability were analyzed. Results The full width of the horizontal epithelium was detected, whereas part of the superior epithelium was not shown for the covered super eyelid. The mean central epithelial corneal thickness was 52.0±3.2 µm for the first measurement and 52.3±3.4 µm for the second measurement (P>.05). In the central zone (0–3.0 mm), the paracentral zones (3.0–6.0 mm) and the peripheral zones (6.0–10.0 mm), the mean epithelial thickness ranged from 51 to 53 µm, 52 to 57 µm, and 58 to 72 µm, respectively. There was no difference between the two tests at both meridians and in the right and left eyes (P>.05). The ICCs of the two tests ranged from 0.70 to 0.97 and the CoRs ranged from 2.5 µm to 7.8 µm from the center to the periphery, corresponding to 5.6% to 10.6% (CoR%). The ICCs of the two observers ranged from 0.72 to 0.93 and the CoRs ranged from 4.5 µm to 10.4 µm from the center to the periphery, corresponding to 8.7% to 15.2% (CoR%). Conclusions This study demonstrated good repeatability of ultra-high resolution and long scan depth SD-OCT to evaluate the entire thickness profiles of the corneal epithelium. The epithelial thickness increases from the center toward the limbus. PMID:24844566

  20. High-resolution recording of particle tracks with in-line holography in a large cryogenic bubble chamber

    NASA Astrophysics Data System (ADS)

    Harigel, Gert G.

    2000-10-01

    Holography has been used successfully in combination with conventional optics for the first time in a large cryogenic bubble chamber, the 15-Foot Bubble Chamber at the Fermi National Accelerator Laboratory (FNAL), during a physics run in a high energy neutrino beam. The innovative system combined the reference beam with the object beam, irradiating a conical volume of approx1.5m3. Bubble tracks from neutrino interactions with a width of approx 120 micrometers have been recorded with good contrast. The ratio of intensities of the object light to the reference light striking the film is called the beam branching ratio (BBR). We obtained in our experiment an exceedingly small minimum- observable ration of BBR = (0.54 divided by 0.21) x 107. The technology has the potential for a wide range of applications. This paper describes the various difficulties in achieving the success. It required the development of laser pulse stretching via enhanced closed loop control with slow Q- switching, to overcome excessive heating of the cryogenic liquid by the powerful laser beam. A sophisticated system of light-absorbing baffles had to be installed to avoid stray light reaching the holographic film. Optical decoupling of classical and holographic illumination systems was required. Real and virtual image replay machines for holograms were built, tailored to our illumination technique.

  1. Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

    NASA Astrophysics Data System (ADS)

    Schaeper, M.; Schmidt, R.; Kostbade, R.; Damaschke, N.; Gimsa, J.

    2016-07-01

    Circular spatial filtering velocimetry (CSFV) was tested during the microscopic registration of the individual rotations of baker’s yeast cells. Their frequency-dependent rotation (electrorotation; ER) was induced in rotating electric fields, which were generated in a glass chip chamber with four electrodes (600 μm tip-to-tip distance). The electrodes were driven with sinusoidal quadrature signals of 5 or 8 V PP with frequencies up to 3 MHz. The observed cell rotation was of the order of 1–100 s per revolution. At each measuring frequency, the independent rotations of up to 20 cells were simultaneously recorded with a high-speed camera. CSFV was software-implemented using circular spatial filters with harmonic gratings. ER was proportional to the phase shift between the values of the spatial filtering signal of consecutive frames. ER spectra obtained by CSFV from the rotation velocities at different ER-field frequencies agreed well with manual measurements and theoretical spectra. Oscillations in the rotation velocity of a single cell in the elliptically polarized field near an electrode, which were resolved by CSFV, could not be visually discerned. ER step responses after field-on were recorded at 2500 frames per second. Analysis proved the high temporal resolution of CSFV and revealed a largely linear torque-friction relation during the acceleration phase of ER. Future applications of CSFV will allow for the simple and cheap automated high-resolution analysis of rotational movements where mechanical detection has too low a resolution or is not possible, e.g. in polluted environments or for gas and fluid vortices, microscopic objects, etc.

  2. Optical high-resolution analysis of rotational movement: testing circular spatial filter velocimetry (CSFV) with rotating biological cells

    NASA Astrophysics Data System (ADS)

    Schaeper, M.; Schmidt, R.; Kostbade, R.; Damaschke, N.; Gimsa, J.

    2016-07-01

    Circular spatial filtering velocimetry (CSFV) was tested during the microscopic registration of the individual rotations of baker’s yeast cells. Their frequency-dependent rotation (electrorotation; ER) was induced in rotating electric fields, which were generated in a glass chip chamber with four electrodes (600 μm tip-to-tip distance). The electrodes were driven with sinusoidal quadrature signals of 5 or 8 V PP with frequencies up to 3 MHz. The observed cell rotation was of the order of 1-100 s per revolution. At each measuring frequency, the independent rotations of up to 20 cells were simultaneously recorded with a high-speed camera. CSFV was software-implemented using circular spatial filters with harmonic gratings. ER was proportional to the phase shift between the values of the spatial filtering signal of consecutive frames. ER spectra obtained by CSFV from the rotation velocities at different ER-field frequencies agreed well with manual measurements and theoretical spectra. Oscillations in the rotation velocity of a single cell in the elliptically polarized field near an electrode, which were resolved by CSFV, could not be visually discerned. ER step responses after field-on were recorded at 2500 frames per second. Analysis proved the high temporal resolution of CSFV and revealed a largely linear torque-friction relation during the acceleration phase of ER. Future applications of CSFV will allow for the simple and cheap automated high-resolution analysis of rotational movements where mechanical detection has too low a resolution or is not possible, e.g. in polluted environments or for gas and fluid vortices, microscopic objects, etc.

  3. Optical performance of the JWST/MIRI flight model: characterization of the point spread function at high resolution

    NASA Astrophysics Data System (ADS)

    Guillard, P.; Rodet, T.; Ronayette, S.; Amiaux, J.; Abergel, A.; Moreau, V.; Augueres, J. L.; Bensalem, A.; Orduna, T.; Nehmé, C.; Belu, A. R.; Pantin, E.; Lagage, P.-O.; Longval, Y.; Glasse, A. C. H.; Bouchet, P.; Cavarroc, C.; Dubreuil, D.; Kendrew, S.

    2010-07-01

    The Mid Infra Red Instrument (MIRI) is one of the four instruments onboard the James Webb Space Telescope (JWST), providing imaging, coronagraphy and spectroscopy over the 5 - 28 μm band. To verify the optical performance of the instrument, extensive tests were performed at CEA on the flight model (FM) of the Mid-InfraRed IMager (MIRIM) at cryogenic temperatures and in the infrared. This paper reports on the point spread function (PSF) measurements at 5.6 μm, the shortest operating wavelength for imaging. At 5.6 μm, the PSF is not Nyquist-sampled, so we use am original technique that combines a microscanning measurement strategy with a deconvolution algorithm to obtain an over-resolved MIRIM PSF. The microscanning consists in a sub-pixel scan of a point source on the focal plane. A data inversion method is used to reconstruct PSF images that are over-resolved by a factor of 7 compared to the native resolution of MIRI. We show that the FWHM of the high-resolution PSFs were 5 - 10 % wider than that obtained with Zemax simulations. The main cause was identified as an out-of-specification tilt of the M4 mirror. After correction, two additional test campaigns were carried out, and we show that the shape of the PSF is conform to expectations. The FWHM of the PSFs are 0.18 - 0.20 arcsec, in agreement with simulations. 56.1 - 59.2% of the total encircled energy (normalized to a 5 arcsec radius) is contained within the first dark Airy ring, over the whole field of view. At longer wavelengths (7.7 - 25.5 μm), this percentage is 57 - 68 %. MIRIM is thus compliant with the optical quality requirements. This characterization of the MIRIM PSF, as well as the deconvolution method presented here, are of particular importance, not only for the verification of the optical quality and the MIRI calibration, but also for scientific applications.

  4. Nitrogen Isotopic Ratio of Cometary Ammonia from High-resolution Optical Spectroscopic Observations of C/2014 Q2 (Lovejoy)

    NASA Astrophysics Data System (ADS)

    Shinnaka, Yoshiharu; Kawakita, Hideyo

    2016-11-01

    The icy materials present in comets provide clues to the origin and evolution of our solar system and planetary systems. High-resolution optical spectroscopic observations of comet C/2014 Q2 (Lovejoy) were performed on 2015 January 11 (at 1.321 au pre-perihelion) with the High Dispersion Spectrograph mounted on the Subaru Telescope on Maunakea, Hawaii. We derive the 14N/15N ratio of NH2 (126 ± 25), as well as the ortho-to-para abundance ratios (OPRs) of the H2O+ ion (2.77 ± 0.24) and NH2 (3.38 ± 0.07), which correspond to nuclear spin temperatures of >24 K (3σ lower limit) and 27 ± 2 K, respectively. We also derive the intensity ratio of the green-to-red doublet of forbidden oxygen lines (0.107 ± 0.007). The ammonia in the comet must have formed under low-temperature conditions at ∼10 K or less to reproduce the observed 14N/15N ratio in this molecule if it is assumed that the 15N-fractionation of ammonia occurred via ion–molecule chemical reactions. However, this temperature is inconsistent with the nuclear spin temperatures of water and ammonia estimated from the OPRs. The interpretation of the nuclear spin temperature as the temperature at molecular formation may therefore be incorrect. An isotope-selective photodissociation of molecular nitrogen by protosolar ultraviolet radiation might play an important role in the 15N-fractionation observed in cometary volatiles.

  5. Bias Correction of high resolution MODIS Aerosol Optical Depth in urban areas using the Dragon AERONET Network

    NASA Astrophysics Data System (ADS)

    Malakar, N. K.; Atia, A.; Gross, B.; Moshary, F.; Ahmed, S. A.; Lary, D. J.

    2013-12-01

    Aerosol optical depth (AOD) is widely used parameter used to quantify aerosol abundance. Satellite retrievals of aerosols over land is fundamentally more complex than aerosol retrieval over oceans. Due to wide coverage and the extensive validation the Moderate Resolution Imaging Spectroradiometer (MODIS), on board the Terra and Aqua satellites is the workhorse instrument used to retrieve AOD from space. However, satellite algorithms of AOD are extremely complex and depends strongly on sun/view geometry, spectral surface albedo, aerosol model assumptions and surface heterogeneity. This issue becomes even more severe when considering the new MODIS 3 km aerosol retrieval products within version 6. To assess satellite retrievals of these high resolution 3 km products, we use the summer 2011 Dragon AERONET data to assess accuracy as well as major retrieval bias that can occur in MODIS measurements. In this study, we explore in detail the factors that can drive these biases statistically. As discussed above, our considers multiple conditions such as surface reflectivity at various wavelengths, solar and sensor zenith angles, the solar and sensor azimuth, scattering angles as well as meteorological factors and aerosol type (angstrom coefficient) etc which are used inputs are used to train neural network in regression mode to compensate for biases against the Dragon AERONET AOD values. In particular, we confirm the results of previous studies where the land cover (urban fraction) appears to be a strong factor in AOD bias and develop a NN estimator which includes land cover directly. The algorithm will be tested not only in the Baltimore/Washington area but assessed in the general North East US where urban biases in the NYC area have been previously identified.

  6. Probing the excited state properties of the highly phosphorescent Pt(dpyb)Cl compound by high-resolution optical spectroscopy.

    PubMed

    Rausch, Andreas F; Murphy, Lisa; Williams, J A Gareth; Yersin, Hartmut

    2009-12-01

    Detailed photophysical studies of the emitting triplet state of the highly phosphorescent compound Pt(dpyb)Cl based on high-resolution optical spectroscopy at cryogenic temperatures are presented {dpyb = N--C(2)--N-coordinated 1,3-di(pyridylbenzene)}. The results reveal a total zero-field splitting of the emitting triplet state T(1) of 10 cm(-1) and relatively short individual decay times for the two higher lying T(1) substates II and III, while the decay time of the lowest substate I is distinctly longer. Further evidence for the assignment of the T(1) substates is gained by emission measurements under high magnetic fields. Distinct differences are observed in the vibrational satellite structures of the emissions from the substates I and II, which are dominated by Herzberg-Teller and Franck-Condon activity, respectively. At T = 1.2 K, the individual spectra of these two substates can be separated by time-resolved spectroscopy. For the most prominent Franck-Condon active modes, Huang-Rhys parameters of S approximately 0.1 can be determined, which are characteristic of very small geometry rearrangements between the singlet ground state and the triplet state T(1). The similar geometries are ascribed to the high rigidity of the Pt(N--C--N) system which, unlike complexes incorporating bidentate phenylpyridine-type ligands and exhibiting similar metal-to-ligand charge transfer admixtures, cannot readily distort from planarity. The results provide new insight into strategies for optimizing the performance of platinum-based emitters for applications such as organic light-emitting diode (OLED) technology and imaging.

  7. A robotic, compact, and extremely high resolution optical spectrograph for a close-in super-Earth survey

    NASA Astrophysics Data System (ADS)

    Ge, Jian; Powell, Scott; Zhao, Bo; Varosi, Frank; Ma, Bo; Sithajan, Sirinrat; Liu, Jian; Li, Rui; Grieves, Nolan; Schofield, Sidney; Avner, Louis; Jakeman, Hali; Yoder, William A.; Gittelmacher, Jakob A.; Singer, Michael A.; Muterspaugh, Matthew; Williamson, Michael; Maxwell, J. E.

    2014-08-01

    One of the most astonishing results from the HARPS and Kepler planet surveys is the recent discovery of close-in super-Earths orbiting more than half of FGKM dwarfs. This new population of exoplanets represents the most dominant class of planetary systems known to date, is totally unpredicted by the classical core-accretion disk planet formation model. High cadence and high precision Doppler spectroscopy is the key to characterize properties of this new population and constrain planet formation models. A new robotic, compact high resolution optical spectrograph, called TOU (formerly called EXPERT-III), was commissioned at the Automatic Spectroscopic Telescope (AST) at Fairborn Observatory in Arizona in July 2013 and has produced a spectral resolution of about 100,000 and simultaneous wavelength coverage of 0.38-0.9 μm with a 4kx4k back-illuminated Fairchild CCD detector. The instrument holds a very high vacuum of 1 micro torr and about 2 mK temperature stability over a month. The early on-sky RV measurements show that this instrument is approaching a Doppler precision of 1 m/s (rms) for bright reference stars (such as Tau Ceti) with 5 min exposures and better than 3 m/s (P-V, RMS~1 m/s) daily RV stability before calibration exposures are applied. A pilot survey of 20 V<9 FGK dwarfs, including known super-Earth systems and known RV stable stars, is being launched and every star will be observed ~100 times over ~300 days time window between this summer and next spring, following up with a full survey of ~150 V< 10 FGKM dwarfs in 2015-2017.

  8. Phacoemulsification Induced Transient Swelling of Corneal Descemet’s Endothelium Complex Imaged with Ultra-High Resolution Optical Coherence Tomography

    PubMed Central

    Shao, Yilei; Wang, Jianhua; Zhao, Yune; Lu, Ping; Lu, Fan

    2013-01-01

    Purpose Thickness changes of corneal sub-layers after phacoemulsification were investigated by spectral domain ultra-high resolution optical coherence tomography (UHR-OCT). Methods The corneas (n = 26) of 26 age-related cataract surgery patients were studied. UHR-OCT was used to evaluate the thickness of Descemet’s Endothelium Complex (DEC), stroma, Bowman’s layer, epithelium, and full cornea at the center (CCT) before, one day after, and one week after surgery. Non-contact specular microscopy measured CCT, endothelial cell density, and morphology. Results The DEC, stroma, Bowman’s layer, and epithelium were visualized by UHR-OCT. Before surgery, the DEC in all cases appeared as a translucent space between two smooth opaque lines. One day after surgery, the posterior corneal surfaces in half of the eyes were wavy and irregular. Compared to the baseline, one day after surgery the thickness increases of the DEC, stroma, and CCT were 4.3 ± 2.6 µm, 25.5 ± 24.9 µm, and 32.1 ± 26.6 µm, respectively (P < 0.001). The morphology of the DEC and the CCT recovered to baseline one week after surgery (P > 0.05), but endothelial cell density was 8.7% less than at baseline. There were no significant changes in Bowman’s layer and epithelium after the operation. The pre-operative DEC thickness was positively correlated with the decreased endothelial cell density at 1 day after surgery (r = 0.55, P = 0.003). Conclusions The DEC showed edematous thickening and different degrees of morphological changes after phacoemulsification. The DEC deformation and corneal edema recovered by one week after surgery, which indicated recovery of endothelial function. UHR-OCT is a useful tool to evaluate function of the DEC after phacoemulsification. Pre-operative DEC thickness may indicate the integrity of the endothelium and could be used for predicting endothelial cell loss after phacoemulsification. PMID:24312254

  9. Rapid and high-resolution imaging of human liver specimens by full-field optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Zhu, Yue; Gao, Wanrong; Zhou, Yuan; Guo, Yingcheng; Guo, Feng; He, Yong

    2015-11-01

    We report rapid and high-resolution tomographic en face imaging of human liver specimens by full-field optical coherence tomography (FF-OCT). First, the arrangement of the FF-OCT system was described and the performance of the system was measured. The measured axial and lateral resolutions of the system are 0.8 and 0.9 μm, respectively. The system has a sensitivity of ˜60 dB and can achieve an imaging rate of 7 fps and a penetration depth of ˜80 μm. The histological structures of normal liver can be seen clearly in the en face tomographic images, including central veins, cords of hepatocytes separated by sinusoidal spaces, and portal area (portal vein, the hepatic arteriole, and the bile duct). A wide variety of histological subtypes of hepatocellular carcinoma was observed in en face tomographic images, revealing notable cancerous features, including the nuclear atypia (enlarged convoluted nuclei), the polygonal tumor cells with obvious resemblance to hepatocytes with enlarged nuclei. In addition, thicker fibrous bands, which make the cytoplasmic plump vesicular nuclei indistinct, were also seen in the images. Finally, comparison between the portal vein in a normal specimen versus that seen in the rare type of cholangiocarcinoma was made. The results show that the cholangiocarcinoma presents with a blurred pattern of portal vein in the lateral direction and an aggregated distribution in the axial direction; the surrounding sinusoidal spaces and nuclei of cholangiocarcinoma are absent. The findings in this work may be used as additional signs of liver cancer or cholangiocarcinoma, demonstrating capacity of FF-OCT device for early cancer diagnosis and many other tumor-related studies in biopsy.

  10. Ultra-high resolution and long scan depth optical coherence tomography with full-phase detection for imaging the ocular surface

    PubMed Central

    Tao, Aizhu; Peterson, Kristen A; Jiang, Hong; Shao, Yilei; Zhong, Jianguang; Carey, Frank C; Rosen, Elias P; Wang, Jianhua

    2013-01-01

    We used a unique combination of four state-of-the-art technologies to achieve a high performance spectral domain optical coherence tomography system suitable for imaging the entire ocular surface. An ultra-high resolution, extended depth range, full-phase interferometry, and high-speed complementary metal-oxide semiconductor transistor camera detection provided unprecedented performance for the precise quantification of a wide range of the ocular surface. We demonstrated the feasibility of this approach by obtaining high-speed and high-resolution images of a model eye beyond the corneal–scleral junction. Surfaces determined from the images with a segmentation algorithm demonstrated excellent accuracy and precision. PMID:23976840

  11. Ultra-high resolution adaptive optics: optical coherence tomography for in vivo imaging of healthy and diseased retinal structures

    NASA Astrophysics Data System (ADS)

    Zawadzki, Robert J.; Zhang, Yan; Jones, Steven M.; Choi, Stacey S.; Cense, Barry; Evans, Julia W.; Miller, Donald T.; Olivier, Scot S.; Werner, John S.

    2008-02-01

    Ultra-high isotropic resolution imaging of retinal structures was made possible with an adaptive optics system using dual deformable mirrors and a Fourier-domain optical coherence tomography (Fd-OCT) system with correction for longitudinal chromatic aberration. This system was used to image microscopic retinal structures of healthy as well as diseased retinas in vivo. The improved resolution and contrast enhanced visualization of morphological structures in the retina can be clearly seen. The benefits of this instrument are apparent from comparison of new images with those acquired using a previous generation AO-OCT instrument. Big change in the appearance of speckle field (reduction in speckle size) can be observed as well. Additionally, further improvements in volumetric data acquisition and image representation will be discussed. This includes creation of large Field of View (FOV) AO-OCT volume from multiple sub-volumes and its visualization. Also techniques and results of reducing speckle contrast by averaging multiple B-scans will be presented.

  12. Observation and Analysis of High-Resolution Optical Line Profiles in Comet Hyakutake (C/1996 B2)

    NASA Astrophysics Data System (ADS)

    Combi, M. R.; Cochran, A. L.; Cochran, W. D.; Lambert, D. L.; Johns-Krull, C. M.

    1999-02-01

    Very high resolution (R~200,000) and high signal-to-noise echelle spectra were obtained of comet Hyakutake (C/1996 B2) using the 2D coudé spectrograph on the 2.7 m telescope at W. J. McDonald Observatory during 1996 in late March and early April. Doppler resolved profiles are presented for individual lines of the major optical neutral species: CN, C2, NH2, O(1D) at 6300 Å, and H Balmer-α at 6563 Å. They are consistent with the expected expansion of a water-dominated cometary coma. Because of the small aperture and the small geocentric distance of the comet, the profiles of CN, C2, and NH2 are totally shaped by the outflowing hydrodynamic coma. The NH2 is the narrowest of the group because of the very short lifetime of the NH2 parent (NH3). The profile of C2 is somewhat broadened, compared with NH2, because of the relatively larger contribution of C2 radicals farther from the nucleus where the bulk outflow speed is larger. Any exothermic ejection speed they receive upon their production would be quenched. Although the profile of CN is broader than C2, this is due to the fact that most of the CN lines are blends of two closely spaced but nearly equal strength components. Because O(1D) atoms in the region samples are produced mainly by the photodissociation of water which results in a prompt emission photon, the line retains contributions of both the basic coma expansion velocity and the 1.6 km s-1 exothermal ejection speed of the O(1D) atoms. The H Balmer-α line is complicated by a chance coincidence of a line of H2O+ and/or NH2 and by optical depth effects in solar Lyβ which are primarily responsible for the Balmer-α excitation. However, the width of the line wings is consistent with other comet observations, including Hyakutake itself, and the production by dissociation of H2O and OH and partial thermalization. We have successfully reproduced these data using a hybrid kinetic/hydrodynamic and Monte Carlo approach which include the important physical

  13. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer.

    PubMed

    Good, Jacob T; Holland, Daniel B; Finneran, Ian A; Carroll, P Brandon; Kelley, Matthew J; Blake, Geoffrey A

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ∼80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  14. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer.

    PubMed

    Good, Jacob T; Holland, Daniel B; Finneran, Ian A; Carroll, P Brandon; Kelley, Matthew J; Blake, Geoffrey A

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ∼80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  15. A decade-spanning high-resolution asynchronous optical sampling terahertz time-domain and frequency comb spectrometer

    NASA Astrophysics Data System (ADS)

    Good, Jacob T.; Holland, Daniel B.; Finneran, Ian A.; Carroll, P. Brandon; Kelley, Matthew J.; Blake, Geoffrey A.

    2015-10-01

    We present the design and capabilities of a high-resolution, decade-spanning ASynchronous OPtical Sampling (ASOPS)-based TeraHertz Time-Domain Spectroscopy (THz-TDS) instrument. Our system employs dual mode-locked femtosecond Ti:Sapphire oscillators with repetition rates offset locked at 100 Hz via a Phase-Locked Loop (PLL) operating at the 60th harmonic of the ˜80 MHz oscillator repetition rates. The respective time delays of the individual laser pulses are scanned across a 12.5 ns window in a laboratory scan time of 10 ms, supporting a time delay resolution as fine as 15.6 fs. The repetition rate of the pump oscillator is synchronized to a Rb frequency standard via a PLL operating at the 12th harmonic of the oscillator repetition rate, achieving milliHertz (mHz) stability. We characterize the timing jitter of the system using an air-spaced etalon, an optical cross correlator, and the phase noise spectrum of the PLL. Spectroscopic applications of ASOPS-THz-TDS are demonstrated by measuring water vapor absorption lines from 0.55 to 3.35 THz and acetonitrile absorption lines from 0.13 to 1.39 THz in a short pathlength gas cell. With 70 min of data acquisition, a 50 dB signal-to-noise ratio is achieved. The achieved root-mean-square deviation is 14.6 MHz, with a mean deviation of 11.6 MHz, for the measured water line center frequencies as compared to the JPL molecular spectroscopy database. Further, with the same instrument and data acquisition hardware, we use the ability to control the repetition rate of the pump oscillator to enable THz frequency comb spectroscopy (THz-FCS). Here, a frequency comb with a tooth width of 5 MHz is generated and used to fully resolve the pure rotational spectrum of acetonitrile with Doppler-limited precision. The oscillator repetition rate stability achieved by our PLL lock circuits enables sub-MHz tooth width generation, if desired. This instrument provides unprecedented decade-spanning, tunable resolution, from 80 MHz down to sub

  16. A high-resolution palaeoenvironmental record from carbonate deposits in the Roman aqueduct of Patara, SW Turkey, from the time of Nero.

    PubMed

    Passchier, Cornelis; Sürmelihindi, Gül; Spötl, Christoph

    2016-01-01

    An inscription on the supporting wall of the inverted siphon of the aqueduct of the ancient Roman city of Patara, SW Turkey, explains how the wall collapsed during an earthquake and was subsequently restored. Carbonate deposits formed inside the aqueduct channel show cyclic stable isotope changes representing 17 years of deposition. This sequence, together with the text of the inscription, allows dating the earthquake to 68 AD and the original inauguration of the aqueduct to the winter of 51/52 AD. Thus, the carbonate deposits represent a high-resolution record of palaeotemperature and precipitation for SW Turkey covering the complete reign of the Emperor Nero. The period shows a cooling and drying trend after an initial warm and more humid period, interrupted by a few anomalous years. These 2 cm of calcite highlight the significance of carbonate deposits in ancient water supply systems as a high-resolution archive for palaeoclimate, palaeoseismology and archaeology.

  17. A high-resolution palaeoenvironmental record from carbonate deposits in the Roman aqueduct of Patara, SW Turkey, from the time of Nero

    NASA Astrophysics Data System (ADS)

    Passchier, Cornelis; Sürmelihindi, Gül; Spötl, Christoph

    2016-06-01

    An inscription on the supporting wall of the inverted siphon of the aqueduct of the ancient Roman city of Patara, SW Turkey, explains how the wall collapsed during an earthquake and was subsequently restored. Carbonate deposits formed inside the aqueduct channel show cyclic stable isotope changes representing 17 years of deposition. This sequence, together with the text of the inscription, allows dating the earthquake to 68 AD and the original inauguration of the aqueduct to the winter of 51/52 AD. Thus, the carbonate deposits represent a high-resolution record of palaeotemperature and precipitation for SW Turkey covering the complete reign of the Emperor Nero. The period shows a cooling and drying trend after an initial warm and more humid period, interrupted by a few anomalous years. These 2 cm of calcite highlight the significance of carbonate deposits in ancient water supply systems as a high-resolution archive for palaeoclimate, palaeoseismology and archaeology.

  18. A high-resolution palaeoenvironmental record from carbonate deposits in the Roman aqueduct of Patara, SW Turkey, from the time of Nero

    PubMed Central

    Passchier, Cornelis; Sürmelihindi, Gül; Spötl, Christoph

    2016-01-01

    An inscription on the supporting wall of the inverted siphon of the aqueduct of the ancient Roman city of Patara, SW Turkey, explains how the wall collapsed during an earthquake and was subsequently restored. Carbonate deposits formed inside the aqueduct channel show cyclic stable isotope changes representing 17 years of deposition. This sequence, together with the text of the inscription, allows dating the earthquake to 68 AD and the original inauguration of the aqueduct to the winter of 51/52 AD. Thus, the carbonate deposits represent a high-resolution record of palaeotemperature and precipitation for SW Turkey covering the complete reign of the Emperor Nero. The period shows a cooling and drying trend after an initial warm and more humid period, interrupted by a few anomalous years. These 2 cm of calcite highlight the significance of carbonate deposits in ancient water supply systems as a high-resolution archive for palaeoclimate, palaeoseismology and archaeology. PMID:27357129

  19. A high-resolution palaeoenvironmental record from carbonate deposits in the Roman aqueduct of Patara, SW Turkey, from the time of Nero.

    PubMed

    Passchier, Cornelis; Sürmelihindi, Gül; Spötl, Christoph

    2016-01-01

    An inscription on the supporting wall of the inverted siphon of the aqueduct of the ancient Roman city of Patara, SW Turkey, explains how the wall collapsed during an earthquake and was subsequently restored. Carbonate deposits formed inside the aqueduct channel show cyclic stable isotope changes representing 17 years of deposition. This sequence, together with the text of the inscription, allows dating the earthquake to 68 AD and the original inauguration of the aqueduct to the winter of 51/52 AD. Thus, the carbonate deposits represent a high-resolution record of palaeotemperature and precipitation for SW Turkey covering the complete reign of the Emperor Nero. The period shows a cooling and drying trend after an initial warm and more humid period, interrupted by a few anomalous years. These 2 cm of calcite highlight the significance of carbonate deposits in ancient water supply systems as a high-resolution archive for palaeoclimate, palaeoseismology and archaeology. PMID:27357129

  20. Toward the Cenozoic Megasplice - high-resolution XRF core scanning data and improved composite records from IODP Expedition 320: implications for fine scale paleoceanography (Invited)

    NASA Astrophysics Data System (ADS)

    Westerhold, T.; Bown, P. R.; Dunkley Jones, T.; Lyle, M. W.; Moore, T. C.; Pälike, H.; Roehl, U.; Wilkens, R. H.; Expedition 320/321 Scientists

    2010-12-01

    A critical need to study past climate change is to sufficiently constrain the ages of past climate events so that global relationships can be discerned. Integrated Ocean Drilling Program (IODP) Expedition 320 recovered high-quality pelagic Cenozoic records with over 800 dated paleomagnetic reversals and decimeter-scale cyclic sediments. These new profiles provide an outstanding framework to inter-calibrate major microfossil groups and refine magnetic polarity chrons for the late Miocene, the entire Oligocene and the late Eocene Epochs. The compilation of a Cenozoic Megasplice which integrates all available bio-, chemo-, and magnetostratigraphic data including those from key records already recovered during Ocean Drilling Program (ODP) Leg 199 is one of the major objectives of the Pacific Equatorial Age Transect (PEAT, IODP Exp. 320 & 321) and prerequisite for further reconstructing the climate history of the Equatorial Pacific in detail. Here we present extended post-cruise refinements of the shipboard composite records of IODP Exp. 320 Sites U1331, U1332, U1333, U1334 as well as ODP Leg 199 Sites 1218, 1219 and 1220. The revised composite records were used to perform a site-to-site correlation and integration of Leg 199 and Exp. 320 sites. Based on this decimeter scale correlation a high resolution integrated paleomagnetic and biostratigraphic framework for the Equatorial Pacific is established which covers the time interval from 20 to 40 Ma. This framework will be the key for further high-resolution paleoceanographic interpretations of the late Paleogene, e.g. the E/O transition. As part of our study we also present high resolution X-ray fluorescence (XRF) core scanning data acquired from more than 1200 meters of sediment cores from Exp. 320 and Leg 199 encompassing the middle Eocene to early Oligocene (magnetochrons C12n to C20n). These new, critical records enable us to improve the orbitally tuned time scale and to reconstruct variations in the carbonate

  1. High-resolution onshore-offshore morpho-bathymetric records of modern chalk and granitic shore platforms in NW France

    NASA Astrophysics Data System (ADS)

    Duperret, Anne; Raimbault, Céline; Le Gall, Bernard; Authemayou, Christine; van Vliet-Lanoë, Brigitte; Regard, Vincent; Dromelet, Elsa; Vandycke, Sara

    2016-07-01

    Modern shore platforms developed on rocky coasts are key areas for understanding coastal erosion processes during the Holocene. This contribution offers a detailed picture of two contrasted shore-platform systems, based on new high-resolution shallow-water bathymetry, further coupled with aerial LiDAR topography. Merged land-sea digital elevation models were achieved on two distinct types of rocky coasts along the eastern English Channel in France (Picardy and Upper-Normandy: PUN) and in a NE Atlantic area (SW Brittany: SWB) in NW France. About the PUN case, submarine steps, identified as paleo-shorelines, parallel the actual coastline. Coastal erosive processes appear to be continuous and regular through time, since mid-Holocene at least. In SWB, there is a discrepancy between contemporary coastline orientation and a continuous step extending from inland to offshore, identified as a paleo-shoreline. This illustrates a polyphased and inherited shore platform edification, mainly controlled by tectonic processes.

  2. High-resolution and nondestructive profile measurement by spectral-domain optical coherence tomography with a visible broadband light source for optical-device fabrication

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Ozaki, Nobuhiko; Oikawa, Yoichi; Miyaji, Kunio; Ohsato, Hirotaka; Watanabe, Eiichiro; Ikeda, Naoki; Sugimoto, Yoshimasa

    2016-08-01

    We developed a spectral-domain optical coherence tomography (OCT) using a visible broadband light source (vis-OCT) for application to high-resolution and nondestructive profile measurement and imaging in semiconductor optical-device fabrication. By using visible broadband light centered at 625 nm and with spectral bandwidth of 260 nm, an axial resolution of 0.69 µm in air was obtained. This was effective for inspection of a transparent photoresist film with thickness of 1-2 µm coated on a semiconductor wafer; the interface between the photoresist film and its substrate and the interface between the photoresist and air were resolved, and the film thickness was measured. In addition, the interface between an opaque epitaxially grown semiconductor layer (Al0.35Ga0.65As) and a GaAs substrate was also detected by vis-OCT. Here we propose a thickness-measurement technique that combines finite-difference time-domain simulation with vis-OCT. This method enables us to determine the thickness of even an optically absorbent epitaxial layer and offers a profile-measurement method that is particularly suitable for the fabrication of semiconductor optical devices.

  3. High-resolution and nondestructive profile measurement by spectral-domain optical coherence tomography with a visible broadband light source for optical-device fabrication

    NASA Astrophysics Data System (ADS)

    Nishi, Tsuyoshi; Ozaki, Nobuhiko; Oikawa, Yoichi; Miyaji, Kunio; Ohsato, Hirotaka; Watanabe, Eiichiro; Ikeda, Naoki; Sugimoto, Yoshimasa

    2016-08-01

    We developed a spectral-domain optical coherence tomography (OCT) using a visible broadband light source (vis-OCT) for application to high-resolution and nondestructive profile measurement and imaging in semiconductor optical-device fabrication. By using visible broadband light centered at 625 nm and with spectral bandwidth of 260 nm, an axial resolution of 0.69 µm in air was obtained. This was effective for inspection of a transparent photoresist film with thickness of 1–2 µm coated on a semiconductor wafer; the interface between the photoresist film and its substrate and the interface between the photoresist and air were resolved, and the film thickness was measured. In addition, the interface between an opaque epitaxially grown semiconductor layer (Al0.35Ga0.65As) and a GaAs substrate was also detected by vis-OCT. Here we propose a thickness-measurement technique that combines finite-difference time-domain simulation with vis-OCT. This method enables us to determine the thickness of even an optically absorbent epitaxial layer and offers a profile-measurement method that is particularly suitable for the fabrication of semiconductor optical devices.

  4. Use of Ultra High Resolution Optical Coherence Tomography to Detect In Vivo Characteristics of Descemet's Membrane in Fuchs' Dystrophy

    PubMed Central

    Shousha, Mohamed Abou; Perez, Victor L.; Wang, Jianhua; Ide, Takeshi; Jiao, Shuliang; Chen, Qi; Chang, Victoria; Buchser, Nancy; Dubovy, Sander R.; Feuer, William; Yoo, Sonia H.

    2009-01-01

    Purpose (1) To demonstrate the capability of ultra high resolution anterior segment optical coherence tomography (UHR-OCT) to image Descemet's membrane (DM) and measure its thickness in vivo. (2) To evaluate the use of DM characteristics and thickness in the diagnosis of Fuchs' dystrophy. Design Case-Control Study Participants 20 eyes of 12 Fuchs' dystrophy patients, 20 eyes of 13 young normal and 20 eyes of 15 elderly normal subjects. Methods Subjects were imaged using novel custom-built UHR-OCT. Images were used to describe the characteristics of DM. Custom-made software was used to measure DM thickness and central corneal thickness (CCT). Specimens of DM obtained from Fuchs' dystrophy patients who underwent endothelial keratoplasty (EK) were histopathologically examined. Regression analyses were used to assess the correlation of DM thickness measured by UHR-OCT in vivo and by light microscopy and to determine the intergroup correlations between age, CCT and DM thickness. Main Outcome Measures DM characteristics and thickness, CCT and age. Results Using UHR-OCT, DM appeared in normal young subjects as a single opaque smooth line and in normal elderly subjects as a band of two smooth opaque lines with a translucent space in between. In Fuchs' dystrophy, DM appeared as a thickened band of two opaque lines; the anterior line was smooth while the posterior line had a wavy and irregular appearance with areas of localized thickenings. DM thickness measured in vivo by UHR-OCT correlated significantly to that measured by light microscopy in five Fuchs' dystrophy eyes that underwent EK. The average central thicknesses of DM in normal young, in normal elderly and in Fuchs' dystrophy eyes were 10 ± 3 μm, 16 ± 2 μm, and 34 ± 11 μm respectively (P < 0.001). There was a significant correlation between age and DM thickness only in normal groups. In Fuchs' dystrophy patients, there was a significant correlation between CCT and DM thickness which was non-significant for

  5. Optical Recording Media Primer

    NASA Astrophysics Data System (ADS)

    Kenny, Tom

    1987-01-01

    This presentation is intended to provide the listener with a general overview of the optical media market. It deals with the basic questions and concerns expressed by those who are about to become involved in optical storage. Areas touched upon include the various types of optical media available, their storage capacities, how they're made, how they are used, life expectancy of media, states of various standards efforts, current and projected pricing and availability, market trends, and growth projecting for the next five years.

  6. Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

    NASA Astrophysics Data System (ADS)

    Beddow, Helen M.; Liebrand, Diederik; Sluijs, Appy; Wade, Bridget S.; Lourens, Lucas J.

    2016-01-01

    The Oligocene-Miocene transition (OMT) (~23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (~3 kyr) benthic foraminiferal oxygen and carbon isotope (δ18O and δ13C) record from Integrated Ocean Drilling Program Site U1334 (eastern equatorial Pacific Ocean), covering the interval from 21.91 to 24.14 Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a ~1‰ increase in benthic foraminiferal δ18O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the equatorial Atlantic and the equatorial Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the δ18O values between infaunal and epifaunal species occurs between 22.8 and 23.2 Ma, associated with the maximum δ18O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of ~50 m across the OMT.

  7. Ultra-high Resolution Carbon Isotope Records in Tree Rings: Indicators of Carbon Allocation and Growing Season Precipitation/Temperature (Invited)

    NASA Astrophysics Data System (ADS)

    Jahren, A.; Schubert, B.

    2010-12-01

    The rapidity and ease of carbon stable isotope measurements on organic substrates has opened the possibility of ultra-high resolution δ13C analyses within tree rings at < 30 to 100 micron increments. We present such measurements for 80 individual tree rings, from 10 trees spanning the last 55 million years in age from arctic, temperate, and tropical environments. Morphological features such as growth rings and resin canals were not preserved in some ancient specimens making identification of annual rings via standard techniques impossible. However, the annual patterns observed in ultra-high resolution δ13C records allowed for characterization of these unknown specimens as evergreen or deciduous. A combination of our data with that published in the literature showed a strong correlation between the amplitude of the δ13C pattern and growing season precipitation/temperature in > 90% of modern evergreen trees examined to date. Ultra-high resolution δ13C analyses of ancient, non-permineralized, evergreen trees could therefore provide quantitative estimates of past climate at annual or seasonal resolution.

  8. A High-Resolution Record of Hydroclimate Changes in the Last Three Millennia from a Stalagmite at DeSoto Caverns (Alabama, USA)

    NASA Astrophysics Data System (ADS)

    Dhungana, R.; Aharon, P.

    2010-12-01

    Late Holocene climate changes in the Southeast USA are poorly documented due to the paucity of high-resolution paleo-records. This study provides high-resolution records of rapid hydroclimate changes in the Southeast over the last three millennia. The records are based on stable isotope rainfall proxies whose time series are constrained by precise U/Th dates from a stalagmite sampled at DeSoto Caverns. The average growth rate of the stalagmite was 149 μm/yr prior to 1400 years and it has been growing with an average growth rate of 42 μm/yr in the last 1400 years. During the past three thousand years stable isotope time series document six wet episodes (at ~ 2950, 2450, 1675, 1200, 700 and 70 years ago) alternating with six drier periods (at ~ 3100, 2800, 1900, 1500, 800 and 300 years ago). The biannually resolved δ18O record agrees well with the contemporaneous SST record from the Sargasso Sea cores suggesting that changes in moisture availability in the Southeast are likely linked to subtropical North Atlantic SST variability. Power spectra analysis of the stalagmite-based oxygen isotope record reveals statistically significant periodicities at 24±1 and 36±1 year that are consistent with those observed in the contemporaneous atmospheric Δ14C production record. The 24 years periodicity is also consistent with the 24-year NAO Index periodicity. On the basis of our analysis we propose that the hydroclimate in the Southeast USA over the last three millennia was intimately linked to NAO variability powered by solar activity fluctuations.

  9. Calibration of optical tweezers with non-spherical probes via high-resolution detection of Brownian motion

    NASA Astrophysics Data System (ADS)

    Butykai, A.; Mor, F. M.; Gaál, R.; Domínguez-García, P.; Forró, L.; Jeney, S.

    2015-11-01

    Optical tweezers are commonly used and powerful tools to perform force measurements on the piconewton scale and to detect nanometer-scaled displacements. However, the precision of these instruments relies to a great extent on the accuracy of the calibration method. A well-known calibration procedure is to record the stochastic motion of the trapped particle and compare its statistical behavior with the theory of the Brownian motion in a harmonic potential. Here we present an interactive calibration software which allows for the simultaneous fitting of three different statistical observables (power spectral density, mean square displacement and velocity autocorrelation function) calculated from the trajectory of the probe to enhance fitting accuracy. The fitted theory involves the hydrodynamic interactions experimentally observable at high sampling rates. Furthermore, a qualitative extension is included in our model to handle the thermal fluctuations in the orientation of optically trapped asymmetric objects. The presented calibration methodology requires no prior knowledge of the bead size and can be applied to non-spherical probes as well. The software was validated on synthetic and experimental data.

  10. High-resolution records of Bonneville Basin paleohydrology offer new insights into changing atmospheric circulation patterns over North America from 26 ka through the Holocene

    NASA Astrophysics Data System (ADS)

    Steponaitis, E.; McGee, D.; Quade, J.; Andrews, A.; Edwards, R.; Hsieh, Y.; Broecker, W. S.; Cheng, H.

    2013-12-01

    The tremendous lateral extent of the Bonneville Basin, which covers much of western Utah, makes paleoclimate records from this region highly sensitive to global-scale changes in atmospheric circulation and hydrology. New paleoclimate records from speleothems and lacustrine carbonates offer insight into the hydrology the Bonneville Basin spanning from 26 ka through the Holocene. Anchored by high-precision U-Th dates, Sr records from crystalline lacustrine carbonates from throughout the basin provide a mechanism for constraining zonal variations in precipitation over time. To accomplish this, we exploit spatial variations in the 87Sr/86Sr ratios of fluvial inputs to Lake Bonneville (Hart et al. 2004). Paired with stable isotope records, these Sr records give a spatially detailed view of the response of Great Basin to global climate change, and by extension, insight into atmospheric circulation patterns over North America during abrupt climate changes. Stable isotope and trace metal records from Lehman Cave speleothems provide a high-resolution extension of these Great Basin hydrological records into the Holocene. Here we provide an overview of these unique paired records, focusing particular attention on the region's response to the Younger Dryas and Heinrich events 1 and 2. Hart, W.S. et al., The 87Sr/86Sr ratios of lacustrine carbonates and lake-level history of the Bonneville paleolake system. GSA Bulletin. 2004; 116: 1107-1119.

  11. An Eight-Century High-Resolution Paleoclimate Record From the Cariaco Basin: Baseline Variability and the 20th Century

    NASA Astrophysics Data System (ADS)

    Black, D. E.; Thunell, R. C.; Kaplan, A.; Tappa, E. J.; Peterson, L. C.

    2007-12-01

    The Cariaco Basin, Venezuela is well-positioned to record a detailed history of surface ocean changes along the southern margin of the Caribbean and the tropical Atlantic. Varved, high deposition rate sediments deposited under anoxic conditions and an abundance of well-preserved microfossils result in one of the few marine records capable of preserving evidence of interannual- to decadal-scale climate variability in the tropical Atlantic. Here we present Mg/Ca and stable oxygen isotope data with sub-decadal resolution derived from sediments deposited over the last 800 years. Mg/Ca measured on the planktic foraminifer Globigerina bulloides from a Cariaco Basin sediment core strongly correlates with spring (March-May) instrumental SSTs between AD 1870 and 1990. The long-term record displays a surprising amount of variability for a tropical location. The temperature swings are not necessarily related to local upwelling variability, but instead represent wider conditions in the Caribbean and western tropical Atlantic. The Mg/Ca-SST record also captures the decadal and multidecadal variability observed in global land and sea surface temperature anomalies, and correlates with Atlantic tropical storm and hurricane frequency over the late-19th and 20th centuries. On average, 20th century temperatures are not the warmest in the entire record, but they do show the largest increase in magnitude and fastest rate of SST change over the last eight hundred years. Stable oxygen isotope data also correlate well with instrumental SSTs, but not over the full instrumental record. Poor correlations with early instrumental SST data suggest a salinity overprint. However, reconstructing δ- water variability using combined Mg/Ca and δ18O data is not straightforward as the δ- water/salinity relationship varies seasonally in the Cariaco Basin. Comparisons with percent titanium data suggest intervals of both local and regional surface salinity changes over the length of the record.

  12. Testing the integrity of stable isotope records of two Spitsbergen ice cores by using high-resolution tritium data.

    NASA Astrophysics Data System (ADS)

    van der Wel, L. G.; Meijer, H. A. J.; Isaksson, E.; Helsen, M. M.; van de Wal, R. S. W.; Martma, T.; Pohjola, V. A.; Moore, J. C.

    2009-04-01

    The ratios of 1H16O2H and 1H18O1H in precipitation water vary with temperature and can therefore be used as a proxy for past climate. Ever since the 1960-s, retrieving these isotope signals has been the main motivation for the drilling of deep ice cores. Most of the ice core records originate from selected sites in Greenland and Antarctica. Other Arctic locations are much less used. However, since the late 1990-s ice cores have been drilled on the Lomonosovfonna and Holtedahlfonna ice caps in Spitsbergen. The advantages of drilling at these sites lies in the high accumulation rate present in Spitsbergen, as well as the very location of the Spitsbergen archipelago. However, due to relatively high temperatures in this region, the isotope record is affected by melt and subsequent percolation, thereby potentially losing its value for climatic studies. In an attempt to test the integrity of the Spitsbergen cores, we measured the concentration of the radioactive isotope of hydrogen (tritium) at high spatial (and thus temporal) resolution. Due to above-ground nuclear bomb tests in the 1950-s and 1960-s, the tritium signal in the atmosphere has been highly variable in that period, with distinct peaks. Moreover, due to the high load of tritium in the stratosphere at that time, spring and early summer mixing between stratosphere and troposphere induced a clear seasonal pattern in precipitation records for two decades. The tritium concentration in precipitation has been measured (monthly average) since the 1950-s. After precipitation the tritium record is altered due to decay, diffusion and melt. Incorporating information of these three processes into a numerical model, we produce a quantitative estimate how much the isotope record is influenced by melt and percolation. This gives us a tool to determine whether the stable isotope record is a valid proxy for past temperatures.

  13. A sediment record of barrier estuary behaviour at the mesoscale: Interpreting high-resolution particle size analysis

    NASA Astrophysics Data System (ADS)

    Clarke, David W.; Boyle, John F.; Chiverrell, Richard C.; Lario, Javier; Plater, Andrew J.

    2014-09-01

    At present, limited understanding of mesoscale (years-decades-centuries) back-barrier lagoon, barrier estuary behaviour is a critical shortcoming for resource managers and decision makers. In this paper, high-resolution particle size analysis of a sediment core from an intermittently open and closed barrier estuary is utilised to reconstruct a history of back-barrier environmental change at mesoscale temporal resolution. Sediments from Pescadero Marsh, California, were analysed for their particle size distribution at consecutive 2-mm intervals down-core. Site selection, informed by a time series of maps and aerial photographs coupled with a robust core chronology, ensured that the particle size data primarily reflect changing hydrodynamics of the back-barrier area over the European-American era (1850 to the present). Following more traditional plotting of particle size data and summary statistics, and statistical analysis of particle size end-members, visual analysis and categorisation of particle size distribution curves (PSDCs) provide an effective basis for the identification of recurring modal sizes and subpopulations. These particle size windows (PSWs) are interpreted as reflecting different modes of sediment transport and deposition, i.e., suspension and saltation loads, the varying prominence of which is interpreted as being modified by barrier integrity. When considered together, the down-core mean particle size (MPS) trend and individual PSDCs offer considerable insight into mesoscale system behaviour at subannual resolution over multiple years. This behaviour is expressed in the recurrence of characteristic barrier estuarine environments (closed lagoon, tidal lagoon, tidal marsh, and open estuary) and the overall barrier regime, and their persistence over the last c. 150 years. Subannual and multiannual fluctuations in back-barrier environmental configuration are seen to be superimposed on a longer-term quasi-stable barrier regime, demonstrating the value

  14. Optical coherence microscopy in 1700 nm spectral band for high-resolution label-free deep-tissue imaging.

    PubMed

    Yamanaka, Masahito; Teranishi, Tatsuhiro; Kawagoe, Hiroyuki; Nishizawa, Norihiko

    2016-01-01

    Optical coherence microscopy (OCM) is a label-free, high-resolution, three-dimensional (3D) imaging technique based on optical coherence tomography (OCT) and confocal microscopy. Here, we report that the 1700-nm spectral band has the great potential to improve the imaging depth in high-resolution OCM imaging of animal tissues. Recent studies to improve the imaging depth in OCT revealed that the 1700-nm spectral band is a promising choice for imaging turbid scattering tissues due to the low attenuation of light in the wavelength region. In this study, we developed high-resolution OCM by using a high-power supercontinuum source in the 1700-nm spectral band, and compared the attenuation of signal-to-noise ratio between the 1700-nm and 1300-nm OCM imaging of a mouse brain under the condition of the same sensitivity. The comparison clearly showed that the 1700-nm OCM provides larger imaging depth than the 1300-nm OCM. In this 1700-nm OCM, the lateral resolution of 1.3 μm and the axial resolution of 2.8 μm, when a refractive index was assumed to be 1.38, was achieved. PMID:27546517

  15. Optical coherence microscopy in 1700 nm spectral band for high-resolution label-free deep-tissue imaging

    NASA Astrophysics Data System (ADS)

    Yamanaka, Masahito; Teranishi, Tatsuhiro; Kawagoe, Hiroyuki; Nishizawa, Norihiko

    2016-08-01

    Optical coherence microscopy (OCM) is a label-free, high-resolution, three-dimensional (3D) imaging technique based on optical coherence tomography (OCT) and confocal microscopy. Here, we report that the 1700-nm spectral band has the great potential to improve the imaging depth in high-resolution OCM imaging of animal tissues. Recent studies to improve the imaging depth in OCT revealed that the 1700-nm spectral band is a promising choice for imaging turbid scattering tissues due to the low attenuation of light in the wavelength region. In this study, we developed high-resolution OCM by using a high-power supercontinuum source in the 1700-nm spectral band, and compared the attenuation of signal-to-noise ratio between the 1700-nm and 1300-nm OCM imaging of a mouse brain under the condition of the same sensitivity. The comparison clearly showed that the 1700-nm OCM provides larger imaging depth than the 1300-nm OCM. In this 1700-nm OCM, the lateral resolution of 1.3 μm and the axial resolution of 2.8 μm, when a refractive index was assumed to be 1.38, was achieved.

  16. Optical coherence microscopy in 1700 nm spectral band for high-resolution label-free deep-tissue imaging

    PubMed Central

    Yamanaka, Masahito; Teranishi, Tatsuhiro; Kawagoe, Hiroyuki; Nishizawa, Norihiko

    2016-01-01

    Optical coherence microscopy (OCM) is a label-free, high-resolution, three-dimensional (3D) imaging technique based on optical coherence tomography (OCT) and confocal microscopy. Here, we report that the 1700-nm spectral band has the great potential to improve the imaging depth in high-resolution OCM imaging of animal tissues. Recent studies to improve the imaging depth in OCT revealed that the 1700-nm spectral band is a promising choice for imaging turbid scattering tissues due to the low attenuation of light in the wavelength region. In this study, we developed high-resolution OCM by using a high-power supercontinuum source in the 1700-nm spectral band, and compared the attenuation of signal-to-noise ratio between the 1700-nm and 1300-nm OCM imaging of a mouse brain under the condition of the same sensitivity. The comparison clearly showed that the 1700-nm OCM provides larger imaging depth than the 1300-nm OCM. In this 1700-nm OCM, the lateral resolution of 1.3 μm and the axial resolution of 2.8 μm, when a refractive index was assumed to be 1.38, was achieved. PMID:27546517

  17. High-Resolution Optical Imaging of Benign and Malignant Mucosa in the Upper Aerodigestive Tract: An Atlas for Image-Guided Surgery

    PubMed Central

    Levy, Lauren L.; Vila, Peter M.; Park, Richard W.; Schwarz, Richard; Polydorides, Alexandros D.; Teng, Marita S.; Gurudutt, Vivek V.; Genden, Eric M.; Miles, Brett; Anandasabapathy, Sharmila; Gillenwater, Ann M.; Richards-Kortum, Rebecca; Sikora, Andrew G.

    2013-01-01

    Background High-resolution optical imaging provides real-time visualization of mucosa in the upper aerodigestive tract (UADT) which allows non-invasive discrimination of benign and neoplastic epithelium. The high-resolution microendoscope (HRME) utilizes a fiberoptic probe in conjunction with a tissue contrast agent to display nuclei and cellular architecture. This technology has broad potential applications to intraoperative margin detection and early cancer detection. Methods Our group has created an extensive image collection of both neoplastic and normal epithelium of the UADT. Here, we present and describe imaging characteristics of benign, dysplastic, and malignant mucosa in the oral cavity, oropharynx, larynx, and esophagus. Results There are differences in the nuclear organization and overall tissue architecture of benign and malignant mucosa which correlate with histopathologic diagnosis. Different anatomic subsites also display unique imaging characteristics. Conclusion HRME allows discrimination between benign and neoplastic mucosa, and familiarity with the characteristics of each subsite facilitates correct diagnosis. PMID:23641314

  18. High-resolution record of cyclic climatic change during the past 4 ka from Lake Turkana, Kenya

    SciTech Connect

    Halfman, J.D.; Johnson, T.C.

    1988-06-01

    Profiles of carbonate content and lamination thickness in an 11.3 m core from Lake Turkana are interpreted as a record of climatic change for the past 4 ka. On a time scale of millennia, the data agree with other paleohydrologic records from sub-Saharan east Africa. Time-series analysis of both data sets reveal periods of about 270, 200, 165, and 100 yr. The thickness data suggest additional periods of about 78, 44, 31, 25, and possibly 20 yr. The sediments consist of laminated light and dark couplets, which are interpreted as a response to an average 4-yr variability in the hydrology of the Ethiopian Plateau. The authors suggest that this may be a feedback from the El Nino-Southern Oscillation.

  19. Nature's crucible: Manufacturing optical nonlinearities for high resolution, high sensitivity encoding in the compound eye of the fly, Musca domestica

    NASA Technical Reports Server (NTRS)

    Wilcox, Mike

    1993-01-01

    The number of pixels per unit area sampling an image determines Nyquist resolution. Therefore, the highest pixel density is the goal. Unfortunately, as reduction in pixel size approaches the wavelength of light, sensitivity is lost and noise increases. Animals face the same problems and have achieved novel solutions. Emulating these solutions offers potentially unlimited sensitivity with detector size approaching the diffraction limit. Once an image is 'captured', cellular preprocessing of information allows extraction of high resolution information from the scene. Computer simulation of this system promises hyperacuity for machine vision.

  20. Large-Scale, High-Resolution Multielectrode-Array Recording Depicts Functional Network Differences of Cortical and Hippocampal Cultures

    PubMed Central

    Ito, Shinya; Yeh, Fang-Chin; Hiolski, Emma; Rydygier, Przemyslaw; Gunning, Deborah E.; Hottowy, Pawel; Timme, Nicholas; Litke, Alan M.; Beggs, John M.

    2014-01-01

    Understanding the detailed circuitry of functioning neuronal networks is one of the major goals of neuroscience. Recent improvements in neuronal recording techniques have made it possible to record the spiking activity from hundreds of neurons simultaneously with sub-millisecond temporal resolution. Here we used a 512-channel multielectrode array system to record the activity from hundreds of neurons in organotypic cultures of cortico-hippocampal brain slices from mice. To probe the network structure, we employed a wavelet transform of the cross-correlogram to categorize the functional connectivity in different frequency ranges. With this method we directly compare, for the first time, in any preparation, the neuronal network structures of cortex and hippocampus, on the scale of hundreds of neurons, with sub-millisecond time resolution. Among the three frequency ranges that we investigated, the lower two frequency ranges (gamma (30–80 Hz) and beta (12–30 Hz) range) showed similar network structure between cortex and hippocampus, but there were many significant differences between these structures in the high frequency range (100–1000 Hz). The high frequency networks in cortex showed short tailed degree-distributions, shorter decay length of connectivity density, smaller clustering coefficients, and positive assortativity. Our results suggest that our method can characterize frequency dependent differences of network architecture from different brain regions. Crucially, because these differences between brain regions require millisecond temporal scales to be observed and characterized, these results underscore the importance of high temporal resolution recordings for the understanding of functional networks in neuronal systems. PMID:25126851

  1. High-resolution chemical and hydrologic records identify environmental factors that control coastal anchialine cave ecosystem function

    NASA Astrophysics Data System (ADS)

    Brankovits, D.; Pohlman, J.; Lapham, L.; Casso, M.; Roth, E.; Lowell, N. S.; Iliffe, T. M.

    2015-12-01

    Anchialine caves host a coastal aquifer ecosystem occupied by cave-adapted crustaceans that reside within distinct fresh, brackish and marine waters. Our initial investigation of this subsurface ecotone in the Yucatan Peninsula (Mexico) provides stable isotope-based evidence that methane and dissolved organic carbon (DOC) are the primary sources of energy and carbon for the food web. However, the frequency of observations is sparse, leaving us 'in the dark' with respect to the temporal dynamics of the ecosystem function. In this study, we obtained undisturbed vertical profiles of methane, DOC and DIC concentration and isotopic composition with the 'Octopipi' water sampler from an anchialine cave located ~8 km from the coastline. To document the temporal variability of methane availability in the cave, we deployed an osmotically-driven pump (OsmoSampler). Data loggers recorded dissolved oxygen (DO), salinity, temperature and current velocities, and a rain gauge recorded precipitation. A high-methane water mass near the ceiling (up to 7795 nM) contained elevated concentration (900 µM), 13C-depleted (-27.8 to -28.2 ‰) DOC, suggesting terrestrial organic matter input from the overlying soils. Low-methane saline water (36 to 84 nM) had lower concentration DOC (15 to 97 µM) with a similar δ13C (-25.9 to -27.2 ‰), suggesting significant terrestrial organic matter consumption or removal with increasing depth, from fresh to saline water, within the water column. Our 6-month water chemistry record reveals high concentrations of methane in the wet season, especially following rainfall events, and relatively lower methane concentrations in the dry season. These observations suggest rain flushes methane generated in overlying anoxic soils into the cave. DO, water level, and groundwater flow patterns were also linked to the precipitation record. These data provide novel insight into the interconnections between external climate forcing and subterranean anchialine

  2. Designing a Low-noise, High-resolution, and Portable Four Channel Acquisition System for Recording Surface Electromyographic Signal.

    PubMed

    Pashaei, Akbar; Yazdchi, Mohammad Reza; Marateb, Hamid Reza

    2015-01-01

    In current years, the application of biopotential signals has received a lot of attention in literature. One of these signals is an electromyogram (EMG) generated by active muscles. Surface EMG (sEMG) signal is recorded over the skin, as the representative of the muscle activity. Since its amplitude can be as low as 50 μV, it is sensitive to undesirable noise signals such as power-line interferences. This study aims at designing a battery-powered portable four-channel sEMG signal acquisition system. The performance of the proposed system was assessed in terms of the input voltage and current noise, noise distribution, synchronization and input noise level among different channels. The results indicated that the designed system had several inbuilt operational merits such as low referred to input noise (lower than 0.56 μV between 8 Hz and 1000 Hz), considerable elimination of power-line interference and satisfactory recorded signal quality in terms of signal-to-noise ratio. The muscle conduction velocity was also estimated using the proposed system on the brachial biceps muscle during isometric contraction. The estimated values were in then normal ranges. In addition, the system included a modular configuration to increase the number of recording channels up to 96. PMID:26951952

  3. Designing a Low-noise, High-resolution, and Portable Four Channel Acquisition System for Recording Surface Electromyographic Signal

    PubMed Central

    Pashaei, Akbar; Yazdchi, Mohammad Reza; Marateb, Hamid Reza

    2015-01-01

    In current years, the application of biopotential signals has received a lot of attention in literature. One of these signals is an electromyogram (EMG) generated by active muscles. Surface EMG (sEMG) signal is recorded over the skin, as the representative of the muscle activity. Since its amplitude can be as low as 50 μV, it is sensitive to undesirable noise signals such as power-line interferences. This study aims at designing a battery-powered portable four-channel sEMG signal acquisition system. The performance of the proposed system was assessed in terms of the input voltage and current noise, noise distribution, synchronization and input noise level among different channels. The results indicated that the designed system had several inbuilt operational merits such as low referred to input noise (lower than 0.56 μV between 8 Hz and 1000 Hz), considerable elimination of power-line interference and satisfactory recorded signal quality in terms of signal-to-noise ratio. The muscle conduction velocity was also estimated using the proposed system on the brachial biceps muscle during isometric contraction. The estimated values were in then normal ranges. In addition, the system included a modular configuration to increase the number of recording channels up to 96. PMID:26951952

  4. Surface water processes in the Indonesian throughflow as documented by a high-resolution coral Δ14C record

    NASA Astrophysics Data System (ADS)

    Fallon, Stewart J.; Guilderson, Thomas P.

    2008-09-01

    To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian throughflow, we have generated a 115-year bimonthly coral-based radiocarbon time series from a coral in the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954, the radiocarbon time series occasionally displays a small seasonal signal (10-15‰). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric 14C content caused by nuclear weapons testing. From 1957 to 1986 the record displays clear seasonal variability from 15 to 60‰ and the post-bomb peak (163 per mil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through the South Makassar Strait. Southern Makassar is under the influence of the Northwest Monsoon, which is responsible for the high austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and upwelling altered) radiocarbon water from the Banda Sea. The coral record also shows a significant 14C peak in 1955 due to the bomb-14C water advected into this region from nuclear weapons tests in the Marshall Islands in 1954.

  5. Recording Approach of Heritage Sites Based on Merging Point Clouds from High Resolution Photogrammetry and Terrestrial Laser Scanning

    NASA Astrophysics Data System (ADS)

    Grussenmeyer, P.; Alby, E.; Landes, T.; Koehl, M.; Guillemin, S.; Hullo, J. F.; Assali, P.; Smigiel, E.

    2012-07-01

    Different approaches and tools are required in Cultural Heritage Documentation to deal with the complexity of monuments and sites. The documentation process has strongly changed in the last few years, always driven by technology. Accurate documentation is closely relied to advances of technology (imaging sensors, high speed scanning, automation in recording and processing data) for the purposes of conservation works, management, appraisal, assessment of the structural condition, archiving, publication and research (Patias et al., 2008). We want to focus in this paper on the recording aspects of cultural heritage documentation, especially the generation of geometric and photorealistic 3D models for accurate reconstruction and visualization purposes. The selected approaches are based on the combination of photogrammetric dense matching and Terrestrial Laser Scanning (TLS) techniques. Both techniques have pros and cons and recent advances have changed the way of the recording approach. The choice of the best workflow relies on the site configuration, the performances of the sensors, and criteria as geometry, accuracy, resolution, georeferencing, texture, and of course processing time. TLS techniques (time of flight or phase shift systems) are widely used for recording large and complex objects and sites. Point cloud generation from images by dense stereo or multi-view matching can be used as an alternative or as a complementary method to TLS. Compared to TLS, the photogrammetric solution is a low cost one, as the acquisition system is limited to a high-performance digital camera and a few accessories only. Indeed, the stereo or multi-view matching process offers a cheap, flexible and accurate solution to get 3D point clouds. Moreover, the captured images might also be used for models texturing. Several software packages are available, whether web-based, open source or commercial. The main advantage of this photogrammetric or computer vision based technology is to

  6. Maar Lake Sediments in the Mediterranean: High-Resolution Archives for Tephra Recording and Paleoenvironmental Reconstruction - a Case Study From Lago Grande di Monticchio (Southern Italy)

    NASA Astrophysics Data System (ADS)

    Negendank, J. F.; Wulf, S.; Brauer, A.; Mingram, J.

    2001-12-01

    Maar lake deposits with sedimentation rates of one or two order of magnitude higher than marine records are excellent archives for the preservation of annual laminations (varves) and thus make available information of the past with a high temporal resolution. In the Mediterranean, such archives are known from maar and crater lakes situated within Quaternary volcanic fields of the Italian Peninsula. Because of the vicinity to high-explosive volcanoes - most of them characterised by numerous tephra producing events during the Late Quaternary - sediments of these sites additionally provide considerable potential for tephrochronological and tephrostratigraphical studies. The maar lake Lago Grande di Monticchio (Mt. Vulture, Basilicata) has turned out to be one of the most suitable sites in Europe. On the one hand, intensive sedimentological, geochemical, palynological and palaeomagnetic studies on numerous laminated sediment cores spanning the last 101 kyr have demonstrated the great potential for palaeoenvironmental reconstruction. The results of these studies indicate a highly variable environment during the last glacial / interglacial cycle with numerous short and abrupt changes, that can be correlated to rapid climate changes recognized in ice-core and deep-sea records. For such comparisons independent chronologies are required. Regarding the sediment record of Lago Grande di Monticchio a varve-supported sedimentation rate chronology has been established based on the counting of annual laminations and interpolation of sedimentation rates for non-varved sections. This chronology has been confirmed by a high-resolution tephrochronology, numerous radiocarbon datings and three 40Ar/39Ar datings on prominent tephra layers. In addition to its value as a high-resolution palaeoclimatic archive, the Monticchio record has become a key position for inter-site correlation in the eastern Mediterranean. This is mainly due to the large number of intercalated tephra layers (n=344

  7. High resolution multi-decadal climate record of the last 1200 years in the southern Gulf of California

    NASA Astrophysics Data System (ADS)

    Pérez-Cruz, L.; Bautista, J. M.; Urrutia-Fucugauchi, J.

    2012-04-01

    A laminated sediment core DIPAL III-T43 from Alfonso Basin was analyzed in order to infer changes in precipitation patterns during the last 1200 years, associated with Monsoon climate. Samples were taken every centimeter and were dried and grounded. Elemental chemical concentrations were measured using an X-Ray fluorescence analyzer (Niton XL3t GOLDD). Alfonso Basin is a small depression located in the Bay of La Paz in the southwestern Gulf of California, due to its location is a sensitive recorder of climate regional variations in the Gulf and in the subtropical Pacific Ocean. Currently, climatic conditions in the Gulf are dominated by seasonal processes (monsoon climate), mainly driven by the position of Subtropical High pressure system and ITCZ. In winter during cool and dry conditions, the ITCZ is located on or below the equator in the Pacific Ocean and strong northwesterly winds dominate, with intense upwelling, promoting increases in primary productivity of surface waters. In the summer, during wet and warm conditions, ITCZ moves northward (~9°N), and southeasterly winds dominate and there is an incursion of the Pacific equatorial current into the Gulf. Local rainfall reaches a maximum and upwelling weakens, with increase terrigenous input to the basin. Age Model is based on radiocarbon AMS dating, estimated sedimentation rate is 0.61 mm/yr, and thus the time scale resolution is multi-decadal Variations in Ti and Fe downcore are used as proxies of past hydrological changes, so higher values are interpreted to reflect increase rainfall, small peninsular drainages and terrigenous input into the basin. In this context, detailed Ti and Fe records reveal important relatively higher concentrations at AD 910, 1008 and 1253, indicating an increase in precipitation. Meanwhile, low Ti and Fe concentration are recorded from AD 1549 to AD 1700 show a tendency towards reduced terrigenous input (precipitation minima) suggesting dry and cool conditions prevailing in the

  8. Surface water processes in the Indonesian Throughflow as documented by a high-resolution coral (Delta)14C record

    SciTech Connect

    Fallon, S J; Guilderson, T P

    2008-04-23

    To explore the seasonal to decadal variability in surface water masses that contribute to the Indonesian Throughflow we have generated a 115-year bi-monthly coral-based radiocarbon time-series from a coral in the Makassar Straits. In the pre-bomb (pre-1955) era from 1890 to 1954, the radiocarbon time series occasionally displays a small seasonal signal (10-15{per_thousand}). After 1954 the radiocarbon record increases rapidly, in response to the increased atmospheric {sup 14}C content caused by nuclear weapons testing. From 1957 to 1986 the record displays clear seasonal variability from 15 to 60{per_thousand} and the post-bomb peak (163 per mil) occurred in 1974. The seasonal cycle of radiocarbon can be attributed to variations of surface waters passing through South Makassar Strait. Southern Makassar is under the influence of the Northwest Monsoon, which is responsible for the high Austral summer radiocarbon (North Pacific waters) and the Southeast Monsoon that flushes back a mixture of low (South Pacific and upwelling altered) radiocarbon water from the Banda Sea. The coral record also shows a significant {sup 14}C peak in 1955 due to bomb {sup 14}C water advected into this region in the form of CaCO{sub 3} particles (this implies that the particles were advected intact and then become entrapped in the coral skeleton--is this what we really mean? Wouldn't even fine particles settle out over the inferred transit time from Bikini to MAK?) or water particles with dissolved labeled CO{sub 2} produced during fallout from the Castle tests in 1954.

  9. High-Resolution, Non-Invasive Imaging of Upper Vocal Tract Articulators Compatible with Human Brain Recordings

    PubMed Central

    Anumanchipalli, Gopala K.; Dichter, Benjamin; Chaisanguanthum, Kris S.; Johnson, Keith; Chang, Edward F.

    2016-01-01

    A complete neurobiological understanding of speech motor control requires determination of the relationship between simultaneously recorded neural activity and the kinematics of the lips, jaw, tongue, and larynx. Many speech articulators are internal to the vocal tract, and therefore simultaneously tracking the kinematics of all articulators is nontrivial—especially in the context of human electrophysiology recordings. Here, we describe a noninvasive, multi-modal imaging system to monitor vocal tract kinematics, demonstrate this system in six speakers during production of nine American English vowels, and provide new analysis of such data. Classification and regression analysis revealed considerable variability in the articulator-to-acoustic relationship across speakers. Non-negative matrix factorization extracted basis sets capturing vocal tract shapes allowing for higher vowel classification accuracy than traditional methods. Statistical speech synthesis generated speech from vocal tract measurements, and we demonstrate perceptual identification. We demonstrate the capacity to predict lip kinematics from ventral sensorimotor cortical activity. These results demonstrate a multi-modal system to non-invasively monitor articulator kinematics during speech production, describe novel analytic methods for relating kinematic data to speech acoustics, and provide the first decoding of speech kinematics from electrocorticography. These advances will be critical for understanding the cortical basis of speech production and the creation of vocal prosthetics. PMID:27019106

  10. High-Resolution, Non-Invasive Imaging of Upper Vocal Tract Articulators Compatible with Human Brain Recordings.

    PubMed

    Bouchard, Kristofer E; Conant, David F; Anumanchipalli, Gopala K; Dichter, Benjamin; Chaisanguanthum, Kris S; Johnson, Keith; Chang, Edward F

    2016-01-01

    A complete neurobiological understanding of speech motor control requires determination of the relationship between simultaneously recorded neural activity and the kinematics of the lips, jaw, tongue, and larynx. Many speech articulators are internal to the vocal tract, and therefore simultaneously tracking the kinematics of all articulators is nontrivial--especially in the context of human electrophysiology recordings. Here, we describe a noninvasive, multi-modal imaging system to monitor vocal tract kinematics, demonstrate this system in six speakers during production of nine American English vowels, and provide new analysis of such data. Classification and regression analysis revealed considerable variability in the articulator-to-acoustic relationship across speakers. Non-negative matrix factorization extracted basis sets capturing vocal tract shapes allowing for higher vowel classification accuracy than traditional methods. Statistical speech synthesis generated speech from vocal tract measurements, and we demonstrate perceptual identification. We demonstrate the capacity to predict lip kinematics from ventral sensorimotor cortical activity. These results demonstrate a multi-modal system to non-invasively monitor articulator kinematics during speech production, describe novel analytic methods for relating kinematic data to speech acoustics, and provide the first decoding of speech kinematics from electrocorticography. These advances will be critical for understanding the cortical basis of speech production and the creation of vocal prosthetics. PMID:27019106

  11. High resolution sedimentary record of dinoflagellate cysts reflects decadal variability and 20th century warming in the Santa Barbara Basin

    NASA Astrophysics Data System (ADS)

    Bringué, Manuel; Pospelova, Vera; Field, David B.

    2014-12-01

    We present a continuous record of dinoflagellate cysts from a core of laminated sediments collected in the Santa Barbara Basin (SBB), off Southern California. The core spans the last ∼260 years and is analysed at biennial (two-year) resolution. Variations in dinoflagellate cyst assemblages are compared with 20th century historical changes, and are used to examine changes in primary productivity and species composition, which are bound to the variability in upwelling and sea-surface temperature (SST) in the region. Cysts produced by heterotrophic dinoflagellates dominate the assemblages. In particular, Brigantedinium spp. (on average 64.2% of the assemblages) are commonly associated with high levels of primary productivity, typically observed under active upwelling conditions, when nutrient supply is higher. Other heterotrophic taxa such as cysts of Protoperidinium americanum, Protoperidinium fukuyoi, Protoperidinium minutum and Archaeperidinium saanichi, all Echinidinium species, Quinquecuspis concreta and Selenopemphix undulata are more abundant in the early part of the record (∼1750s-1870s). These taxa are generally associated with high primary productivity and are observed predominantly during intervals marked by relatively variable conditions of SST, stratification and nutrient loading. The 20th century is marked by an increase in several species of autotrophic affinity, primarily Lingulodinium machaerophorum and Spiniferites ramosus. In recent surface sediments from the region, these species are more abundant in the Southern California Bight, and they are associated with conditions of relaxed upwelling in the SBB (typically observed during summer and fall), when SST is higher and nutrient supply is moderate. Their increasing concentrations since the early 20th century reflect warmer SST and possibly stronger stratification during the warmest season. Taken together, the changes in cyst assemblages provide further evidence that persistently warmer conditions

  12. High resolution trace element records from the deep sea hydrocoral Stylaster venustus: Implications for stylasterids as a paleoceanographic archive

    NASA Astrophysics Data System (ADS)

    Aranha, R. S.; Layne, G. D.; Edinger, E.; Piercey, G.

    2009-12-01

    Stylasterids are one of the lesser known groups of deep sea corals, but appear to have potential to serve as viable geochemical archives for reconstructing temperature, salinity and nutrient regimes in the deep ocean. This group of hydrocorals are present in most, if not all of the world’s major oceans. Stylasterid species dominantly have aragonitic skeletons, with a small percentage of species having calcitic skeletons (1). A recent study on the biomineralization of a deep sea stylasterid (Errina dabneyi) has revealed that during the organism’s growth, a steady dissolution and reprecipitation of skeletal material occurs in the central canals of the skeleton. This skeletal modification likely alters the stable isotope and/or trace element profiles of these corals, making them potentially less reliable as geochemical archives, depending on the scale of sampling (2). Recent specimens of Stylaster venustus were collected in July, 2008 from the Olympic Coast National Marine sanctuary off the coast of Washington at depths of 200 - 350 m. We used a Cameca IMS 4f Secondary Ion Mass Spectrometer (SIMS) to perform high spatial resolution (<25 µm) spot analyses of Sr/Ca, Mg/Ca and Na/Ca in detailed traverses across the basal cross-sections from three of these specimens. We identified the remineralized material by remnant porous texture and/or a substantially different trace element composition. Spot analyses corresponding to the remineralized material were eliminated from the dataset. In all three specimens we observed a pronounced inverse correlation (r = -0.36) of Mg/Ca and Sr/Ca profiles throughout the length of the transects . A positive correlation (r =0.46) between Na/Ca and Mg/Ca profiles was also noted in two of the specimens analyzed. These correlations strongly imply that the coral skeleton is recording either cyclical or episodic variations in temperature, with possible overprinting from other environmental variation. The exact relationship between the

  13. Climate variability in south-eastern Australia over the last 1500 years inferred from the high-resolution diatom records of two crater lakes

    NASA Astrophysics Data System (ADS)

    Barr, Cameron; Tibby, John; Gell, Peter; Tyler, Jonathan; Zawadzki, Atun; Jacobsen, Geraldine E.

    2014-07-01

    Climates of the last two millennia have been the focus of numerous studies due to the availability of high-resolution palaeoclimate records and the occurrence of divergent periods of climate, commonly referred to as the ‘Medieval Climatic Anomaly' and ‘The Little Ice Age'. The majority of these studies are centred in the Northern Hemisphere and, in comparison, the Southern Hemisphere is relatively under-studied. In Australia, there are few high-resolution, palaeoclimate studies spanning a millennium or more and, consequently, knowledge of long-term natural climate variability is limited for much of the continent. South-eastern Australia, which recently experienced a severe, decade-long drought, is one such region. Results are presented of investigations from two crater lakes in the south-east of mainland Australia. Fluctuations in lake-water conductivity, a proxy for effective moisture, are reconstructed at sub-decadal resolution over the past 1500 years using a statistically robust, diatom-conductivity transfer function. These data are interpreted in conjunction with diatom autecology. The records display coherent patterns of change at centennial scale, signifying that both lakes responded to regional-scale climate forcing, though the nature of that response varied between sites due to differing lake morphometry. Both sites provide evidence for a multi-decadal drought, commencing ca 650 AD, and a period of variable climate between ca 850 and 1400 AD. From ca 1400-1880 AD, coincident with the timing of the ‘Little Ice Age', climates of the region are characterised by high effective moisture and a marked reduction in inter-decadal variability. The records provide context for climates of the historical period and reveal the potential for more extreme droughts and more variable climate than that experienced since European settlement of the region ca 170 years ago.

  14. Understanding Abrupt, Natural Climate Variability Post-Industrial Revolution from the Subtropical Eastern Pacific: A Novel High Resolution Alkenone-derived Sea Surface Temperature Record

    NASA Astrophysics Data System (ADS)

    Kelly, C. S.; O'Mara, N. A.; Herbert, T.; Abella-Gutiérrez, J. L.; Herguera, J. C.

    2015-12-01

    Despite the ocean's importance in global biogeochemical feedbacks and heat storage, there is still a paucity of decadally-resolved sea surface temperature (SST) records to complement lacustrine and dendrological records of recent paleoclimate. Natural climate variability on multidecadal timescales is dominated by internal ocean circulation dynamics and feedbacks, and it is therefore imperative to employ marine proxies to reconstruct high resolution climate change. The timescales of this ocean-induced natural climate variability can be broken down into a few characteristic climate modes. Pressing questions about these modes include their stationarity in frequency and amplitude over time, in addition to the hypothesis that anthropogenic climate change has altered their behavior in comparison to natural variability. To pursue these questions, we must discern and analyze suitable climate archives in regions where modes of interest dominate modern climate variability. The region of Baja California, Mexico exhibits exceptional teleconnection to the El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation (PDO). Local, dramatic effects of ENSO and PDO on the marine biology and economy underline the importance of regional paleoclimate records from the Baja peninsula. Here, we present a high-resolution alkenone-derived SST reconstruction from the Industrial Revolution through the year 2000 by analysis of laminated box and Kasten sediment cores at Site PCM 00-78 (25.18°N, 112.66°W) in the subtropical eastern Pacific at a depth of 540 meters. Our SST record corresponds with NOAA extended reconstructed sea surface temperature, providing a robust basis for organic geochemical marine climatic reconstructions on timescales usually accessible only through speleothems, coral density bands, tree rings, and the like. Accordingly, based on this comparison to the historical data we expect our SST record may provide a more robust record of inter and multidecadal

  15. A High-Resolution Late Holocene Record of Rainfall From Lake Edward, Equatorial Africa: Linkages Between the African and Indian Monsoons

    NASA Astrophysics Data System (ADS)

    Russell, J. M.; Johnson, T. C.

    2005-12-01

    High-resolution analyses of the chemical composition of calcite and the biogenic silica content of sediments from piston cores spanning the past 3,500 years from Lake Edward, Uganda-Congo, document multidecadal to millennial-scale climate variability in the heart of equatorial Africa. Major drought events in the Lake Edward record occur at about 500, 850, 1500, ~2000, and 2700 cal yr BP, in addition to numerous other events of lesser magnitude/duration. Comparison of our record to other Holocene records of African lake levels suggests that most of these intervals of drought affected most of equatorial East Africa. However, wet conditions at about 500 cal yrs BP at sites to the east of Lake Edward could indicate spatial heterogeneity within the African continent during the "Little Ice Age", which could have resulted from complex interactions between the African (Atlantic) and Indian Ocean monsoons. Spectral analysis of our drought record, sampled at a 3-year step, shows evidence for numerous multidecadal to century-scale drought periods in the region. The periodicities observed do not appear linked to solar forcing; rather, periods of ~125, ~70, ~28, and ~18 years apparent in our record as well as other records from the Indian Ocean basin may arise from climate variability internal to the tropical oceans, in particular the Indo-Pacific. Lastly, the Lake Edward record suggests that the climate of equatorial Africa has been unusually stable and generally wet for the past ca. 100 years. This stability appears unusual in light of the considerable climate variability suggested by our record for the past several millennia, a finding with clear implications for East African societies.

  16. The Optical Spectrum of SrOH Re-Visited Zeeman Effect, High-Resolution Spectroscopy and Franck-Condon Factors.

    NASA Astrophysics Data System (ADS)

    Nguyen, Trung; Kokkin, Damian L.; Steimle, Timothy; Kozyryev, Ivan; Doyle, John M.

    2015-06-01

    Motivated by a diverse range of applications in physics and chemistry, currently there is great interest in the cooling of molecules to very low temperatures (≤1 mK). Direct laser cooling has been previously demonstrated for the diatomic radicals SrF, YO, and CaF, and most recently a three-dimensional magneto-optical trap (MOT) of SrF molecules was achieved. To determine the possibility of laser cooling for polyatomic molecules containing three or more atoms, detailed information is required about their Franck-Condon factors (FCFs) for emission from the excited states of interest. Here we report on the high-resolution laser excitation spectra, recorded field-free and in the presence of a static magnetic field, and on the dispersed fluorescence (DF) spectra for the A^2Π1/2 ← X^2σ^+ and B^2σ^+ ← X ^2σ^+ electronic transitions of SrOH. The DF spectra were analyzed to precisely determine FCFs and compared with values predicted using a normal coordinate GF matrix approach. The recorded Zeeman spectra were analyzed to determine the magnetic moments. Implication for proposed laser cooling and trapping experiments for SrOH will be presented. E.S. Shuman, J.F. Barry and D. DeMille, Nature 467, 820 (2010) J.F. Barry, E.S. Shuman, E.B. Norrgard and D. DeMille, Phys. Rev. Lett. 108, 103002 (2012) M.T. Hummon, M. Yeo, B.K. Stuhl, A.L. Collopy, Y. Xia, and J. Ye, Phys. Rev. Lett. 110, 143001 (2013) M. Yeo, M.T. Hummon, A.L. Collopy, B. Yan, B. Hemmerling, E. Chae, J.M. Doyle, and J. Ye, arXiv:1501.04683 (2015) V. Zhelyazkova, A. Cournol, T.E. Wall, A. Matsushima, J.J. Hudson, E.A. Hinds, M.R. Tarbutt, and B.E. Sauer, Phys. Rev. A 89, 053416 (2014) J.F. Barry, D.J. McCarron, E.B. Norrgard, M.H. Steinecker and D. DeMille, Nature 512, 286 (2014) D.J. McCarron, E.B. Norrgard, M.H. Steinecker and D. DeMille, arXiv:1412.8220 (2014)

  17. Early Holocene variability in the Arctic Gateway - High-resolution records reflecting Atlantic Water advection and ice coverage

    NASA Astrophysics Data System (ADS)

    Spielhagen, Robert F.; Bauch, Henning A.; Maudrich, Martin; Not, Christelle; Telesinski, Maciej M.; Werner, Kirstin

    2015-04-01

    The Arctic Gateway between Greenland and Svalbard is the main passage for the advection of Atlantic Water to the Arctic Ocean. Water temperature and intensity of this advection largely determine the degree of ice coverage which is fed by sea ice export from the north. Supported by a maximum in insolation, the Early Holocene was a period of extraordinarily strong advection and relatively high near-surface water temperatures in the eastern Nordic Seas (cf. Risebrobakken et al., 2011, Paleoceanography v. 26). Here we present a synthesis of radiocarbon-dated records from the northern and western part of this area, reaching from the SW Greenland Sea (73°N) to the Yermak Plateau (81°N) and revealing temporal and spatial differences in the development of the so-called Holocene Thermal Maximum (HTM). In the northern part of this region, the HTM started ca. 11-10.5 ka as indicated by rapidly increasing amounts of subpolar planktic foraminifers in the sediments. In the eastern Fram Strait and on the Yermak Plateau, our records of (sub)millennial scale resolution show that the maximum influx terminated already 2,000 years later (9-8 ka). Most likely, this development went along with a N-S relocation of the sea ice margin. According to the current stratigraphic model for a core with submillennial-scale resolution from Vesterisbanken seamount (73°N) in the Greenland Sea, the timing was different there. Increasing total amounts of planktic foraminifers in the sediment indicate an early (11-10 ka) reduction in sea ice coverage also in this region. However, evidence from subpolar planktic foraminifers for maximum Atlantic Water advection is younger (9-6 ka) than in the north. Apparently, the site in the SW Greenland Sea was affected by Atlantic Water in the Greenland Gyre that decoupled from the northward flowing Norwegian Atlantic Current/Westspitsbergen Current south of the Fram Strait. Thus, in a suite of events, strong Atlantic Water advection first affected the

  18. Interglacial Greenland aerosol deposition: comparison of continuous high resolution chemical ice core records from the Eemian and Holocene

    NASA Astrophysics Data System (ADS)

    Gfeller, Gideon; Bigler, Matthias; Schüpbach, Simon; Mini, Olivia; Leuenberger, Daiana; Fischer, Hubertus

    2014-05-01

    Earth's climate system has been oscillating over the last million years between cold glacials and warm interglacials, leaving the imprints of their climate states in form of isotopes variations and chemical impurities in polar ice caps. In the course of the North Greenland Eemian Ice Drilling (NEEM) project, the NEEM ice core has been entirely analysed in very high depth resolution with a Continuous Flow Analysis (CFA) system for the concentrations of chemical aerosol tracers in the ice. Only in the brittle ice zone (600-1100 m depth equivalent to the time interval 3000-8000 years before present) most of the ice had to be discarded due to multifractured core material. Based on the unique reconstructed age scale to unfold the stratigraphically disturbed part from about 2200 m depth downwards (NEEM community members, Nature, 2013), we are able to present the first Greenland chemistry record over the entire last interglacial, the so called Eemian period (about 128'000 to 115'000 years ago). As the Eemian is believed to have been 4 to 8 degrees C warmer than the modern climate, it can be used as an analogue for our present warming climate and, thus, contributes to a better understanding of processes causing natural variations. By means of the chemistry records we are able to assess the natural variability of Greenland Eemian climate and gain insight in its biogeochemical state. Here, short-term variability as well as long term trends of soluble chemical impurities in the Eemian are investigated and compared with those in the Holocene. Changes of organic processes in soils and biomass burning for example are assessed through soluble ammonium and nitrate concentrations. In comparison to the Holocene, ammonium concentrations were about 25% higher during the Eemian. Nitrate, on the other hand, shows about 25% lower concentrations. Sodium concentrations, reflecting changes in sea salt aerosol, are about 35% lower during the Eemian than during the Holocene. Calcium

  19. Two high resolution terrestrial records of atmospheric Pb deposition from New Brunswick, Canada, and Loch Laxford, Scotland.

    PubMed

    Kylander, Malin E; Weiss, Domink J; Kober, Bernd

    2009-02-15

    Environmental archives like peat deposits allow for the reconstruction of both naturally and anthropogenically forced changes in the biogeochemical cycle of Pb as well as the quantification of past and present atmospheric Pb pollution. However, records of atmospheric Pb deposition from pre-industrial times are lacking. In a publication by Weiss et al. [Weiss, D., Shotyk, W., Boyle, E.A., Kramers, J.D., Appleby, P.G., Cheburkin, A.K., Comparative study of the temporal evolution of atmospheric lead deposition in Scotland and eastern Canada using blanket peat bogs. Sci Total Environ 2002;292:7-18]. Pb isotopes data measured by Q-ICP-MS and TIMS, concentration and enrichment data was presented for sites in eastern Canada (PeW1) and northwestern Scotland (LL7c), dating to 1586 A.D and 715 A.D., respectively. Here these same cores are re-analysed for Pb isotopes by MC-ICP-MS thereby acquiring 204Pb data and improving on the original data in terms of resolution and temporal coverage. Significant differences were found between the Q-ICP-MS/TIMS and MC-ICP-MS measurements, particularly at PeW1. These discrepancies are attributed to the problematic presence of organic matter during sample preparation and analysis complicated by the heterogeneity of the organic compounds that survived sample preparation steps. The precision and accuracy of Pb isotopes in complex matrices like peat is not always well estimated by industrial standards like NIST-SRM 981 Pb. Lead pollution histories at each site were constructed using the MC-ICP-MS data. The entire LL7c record is likely subject to anthropogenic additions. Contributions from local mining were detected in Medieval times. Later, coal use and mining in Scotland, Wales and England became important. After industrialization (ca. 1885 A.D.) contributions from Broken Hill type ores and hence, leaded petrol, dominate atmospheric Pb signatures right up to modern times. At PeW1 anthropogenic impacts are first distinguishable in the late 17th

  20. A Millennial Length High-Resolution Pollen, Charcoal, Diatom and Stable Isotope Record from Laguna San Carlos, Panama

    NASA Astrophysics Data System (ADS)

    St Jacques, J. M.; Escobar, J.; Velez, M.; Correa-Metrio, A.; Curtis, J. H.

    2014-12-01

    We report here on preliminary results from Laguna San Carlos, (8o 37' 32.44''N, 80o 03' 04.24'' W) a small, shallow (8.3 m) volcanic lake from west-central Panama, a relatively unstudied Pacific coast region that is an important location for paleo-ENSO studies. The circular lake is a closed basin lake with a gradually sloping shoreline located within a caldera. The 300 cm core was taken in 2 m of water during March 2010. The core bottom was resting upon basement granitic rock with feldspar phenocrystals. The chronology is based upon five radiocarbon dates from terrestrial plant and wood remains. Pollen and charcoal were sampled at 10 cm resolution, diatoms at 5 cm and stable isotopes at 1 cm. The pollen profile shows four distinct terrestrial vegetation units. During the Medieval Climate Anomaly (MCA), from AD 880-1485, the vegetation was sparse with high amounts of grass, Asteraceae and charcoal suggestive of grasslands with high rates of natural disturbance, including fire. With the onset of the Little Ice Age (LIA), during AD 1485-1570, the vegetation transitioned into an open dry forest characterized by Myrica and Anacardium with high seasonality in precipitation. At AD 1570, the climate became wetter as shown by the pollen typical of a moist tropical forest. This lasted until AD 1720 when a period of greater human disturbance began (as shown by increased sedimentation rates), with primary forest taxa cohabiting with grasses and secondary taxa. The first maize pollen appeared at ~AD 1700. The diatom record is dominated by a single eutrophic species, Fragilaria crotonensis; however from AD 880-1150 minor taxa such as Aulacoseira spp., indicative of increased turbulence appeared, supporting the pollen record of open canopy vegetation at this time. The sedimentary carbon/nitrogen ratio (C/N) shows that the majority of the organic remains in the lake have always come from the surrounding basin. MTM spectral analysis of percent Fragilaria crotonensis, percent carbon

  1. High-resolution records detect human-caused changes to the boreal forest wildfire regime in interior Alaska

    USGS Publications Warehouse

    Gaglioti, Benjamin V.; Mann, Daniel H.; Jones, Benjamin M.; Wooller, Matthew J.; Finney, Bruce P.

    2016-01-01

    Stand-replacing wildfires are a keystone disturbance in the boreal forest, and they are becoming more common as the climate warms. Paleo-fire archives from the wildland–urban interface can quantify the prehistoric fire regime and assess how both human land-use and climate change impact ecosystem dynamics. Here, we use a combination of a sedimentary charcoal record preserved in varved lake sediments (annually layered) and fire scars in living trees to document changes in local fire return intervals (FRIs) and regional fire activity over the last 500 years. Ace Lake is within the boreal forest, located near the town of Fairbanks in interior Alaska, which was settled by gold miners in AD 1902. In the 400 years before settlement, fires occurred near the lake on average every 58 years. After settlement, fires became much more frequent (average every 18  years), and background charcoal flux rates rose to four times their preindustrial levels, indicating a region-wide increase in burning. Despite this surge in burning, the preindustrial boreal forest ecosystem and permafrost in the watershed have remained intact. Although fire suppression has reduced charcoal influx since the 1950s, an aging fuel load experiencing increasingly warm summers may pose management problems for this and other boreal sites that have similar land-use and fire histories. The large human-caused fire events that we identify can be used to test how increasingly common megafires may alter ecosystem dynamics in the future.

  2. High-resolution sedimentary record of the last deglaciation from a high-altitude lake in Ethiopia

    NASA Astrophysics Data System (ADS)

    Tiercelin, J.-J.; Gibert, E.; Umer, M.; Bonnefille, R.; Disnar, J.-R.; Lézine, A.-M.; Hureau-Mazaudier, D.; Travi, Y.; Keravis, D.; Lamb, H. F.

    2008-03-01

    Sedimentological and geochemical studies conducted on a 15.82-m long core collected from Lake Garba Guracha (Ethiopia) associated with a precise AMS- 14C time-scale document a unique record of the sedimentary processes linked to the progressive retreat of a high-altitude glacier in the Bale Mountains since 17,000 yr cal BP. Lake sedimentation is interpreted as the result of discharges of meltwater and glaciogenic sediment which progressively filled the accommodation space generated by glacier retreat within the basin. Monogenic sediment originated from glacial erosion of the trachytic tuff forming the cirque floor. Ice melting ended progressively between 12,600 and 11,800 cal BP, as suggested by the decrease in sedimentation energy followed by a sharp change in sedimentary facies. From 11,800 cal BP, the lake reached its maximum development and clastic input was replaced by organic-rich sedimentation. This relates to a major increase of lake productivity, which lasted up to 4500 cal BP. From this period, a lowering in productivity reflects the widespread dryness which occurred throughout the East African tropics.

  3. A high resolution tephrochronological record of MIS 14-12 in the Southern Apennines (Acerno Basin, Italy)

    NASA Astrophysics Data System (ADS)

    Petrosino, P.; Jicha, B. R.; Mazzeo, F. C.; Russo Ermolli, E.

    2014-03-01

    Lithological, mineralogical, and glass chemical analyses on juvenile fragments extracted from 20 tephra layers embedded within the lacustrine sediments of the Acerno Basin (Southern Apennines, Italy) were carried out together with four sanidine 40Ar/39Ar age determinations. The measured ages span the interval between 561 and 493 ka. Middle Pleistocene eruptive activity at Roman Province volcanoes was identified as the main possible source of the investigated tephra layers. Some of them were correlated with precise terrestrial counterparts corresponding to large explosive events of the Sabatini (e.g. Tufo Giallo della Via Tiberina) and Alban Hills volcanic districts (e.g. Tufo Pisolitico di Trigoria). The integration of tephrochronology and pollen analyses allowed the Acerno lacustrine sedimentation to be constrained between MIS 14 and 12, which overlaps with several well-studied, lacustrine successions of the Southern Apennines. The correlation with other tephrostratigraphic records from intramontane basins in central-southern Apennines testifies to the wide dispersal of at least three tephra layers that serve as marker layers, thus improving the resolution of the Middle Pleistocene Italian tephrostratotype.

  4. A high-resolution multi-proxy stalagmite record from Mechara, Southeastern Ethiopia: palaeohydrological implications for speleothem palaeoclimate reconstruction

    NASA Astrophysics Data System (ADS)

    Asrat, Asfawossen; Baker, Andy; Umer Mohammed, Mohammed; Leng, Melanie J.; van Calsteren, Peter; Smith, Claire

    2007-01-01

    An annually laminated stalagmite from Southeastern Ethiopia grew for 443+/-8 yr starting at 5023 yr BP (+/-160 yr) as determined by lamina-tuned U-Th dating. The speleothem shows three growth phases: (1) an initial phase where the stalagmite has a candlestick shape, deposited by relatively slow rate drip water; (2) a middle growth phase where laminae grow on the flanks, suggesting faster drip rates; and (3) a final growth phase where the speleothem becomes narrower owing to a decrease in drip water supply towards the end of deposition. Morphometry, annual growth rate, fluorescence index, and 234U/238U isotope ratio show marked differences between the growth phases, while 13C and 18O do not show significant variation, except within the third phase towards the top of the stalagmite, where they have higher values. The study indicates that the multiproxy approach is crucial as the different proxies respond to single climate forcing in different manners. Our results can be widely applied to speleothem studies distinguishing the relative importance of the various proxies in recording cave external (climate, hydrology) and cave internal (e.g. evaporation) processes. Copyright

  5. Development of a high-resolution record of Great Basin climate change during MIS 5, 6, and 7

    NASA Astrophysics Data System (ADS)

    Cross, M.; McGee, D.; Broecker, W. S.; Quade, J.; Cheng, H.; Edwards, R.

    2013-12-01

    As evinced by the cycles of the large paleolakes Lahontan and Bonneville, the currently semi-arid to arid Great Basin region of the United States has experienced significant changes in climate and water balance in the past. Although there has been substantial research concerning these changes for times around and since the last glacial maximum, relatively little is known about the region's previous climate and water balance history. There is a clear need for a long-term record for earlier glacial and interglacial periods. Here, we present some of our initial results from Lehman Cave (39.01°N, 114.22°W), a well-decorated, active cave located on the edge of the Bonneville Basin in the Great Basin National Park, for times correlating with large portions of Marine Oxygen Isotope Stages (MIS) 5, 6, and 7. We initially surveyed a suite of speleothems to obtain times and durations of growth phases to aid in choosing samples appropriate for more extensive analysis. Approximately eighty 2 to 10 mg samples with a mean 238U of 400 ppb, representing most of the major growth phases of this suite of 20 speleothems, were analyzed for preliminary uranium-thorium dates. A subset of eight of these stalagmites grew collectively over large portions of MIS 5 and 6 (an interval that includes the Little Valley lake cycle of the Bonneville Basin) as well as a substantial portion of MIS 7. This record includes several significant periods of contemporaneous growth, including: 81.5 to 103 ka, which corresponds to the interval between Dansgaard-Oeschger events 21 and 23; 204 to 207 ka; and 118 to 132 ka, an interval including the beginning of the last interglacial period and the end of Termination II and Heinrich Stadial 11. We have yet to identify growth phases between 103 to 118 ka, 134 to 137 ka, and 164 to 169 ka. Initial stable isotope results indicate a shift of approximately +3‰ δ18O and +5‰ δ13C around 131 × 2.5 ka, which agrees within error with the findings of Shakun et al

  6. High-resolution interrogation technique for fiber optic extrinsic Fabry-Perot interferometric sensors by the peak-to-peak method

    NASA Astrophysics Data System (ADS)

    Jiang, Yi

    2008-03-01

    An improved peak-to-peak method is developed for interrogating the absolute cavity length of fiber optic extrinsic Fabry-Perot interferometric (EFPI) sensors with high resolution. A fiber Fabry-Perot tunable filter (FFP-TF) is used to scan the optical spectrum of an EFPI, and the problems caused by the nonlinear performance and poor repeatability of the FFP-TF are removed by using a wavelength calibration technique. A linear fitting is used to calculate the wavelength spacing between two adjacent apexes in the optical spectrum, and the cavity length can be retrieved using this wavelength spacing. The experimental results show that the measuring resolution is improved from 25 to 1 μm, and a linear output is also obtained.

  7. Ultra-high-resolution paleoenvironmental records via direct laser-based analysis of lipid biomarkers in sediment core samples

    PubMed Central

    Wörmer, Lars; Elvert, Marcus; Fuchser, Jens; Lipp, Julius Sebastian; Buttigieg, Pier Luigi; Zabel, Matthias; Hinrichs, Kai-Uwe

    2014-01-01

    Marine microorganisms adapt to their habitat by structural modification of their membrane lipids. This concept is the basis of numerous molecular proxies used for paleoenvironmental reconstruction. Archaeal tetraether lipids from ubiquitous marine planktonic archaea are particularly abundant, well preserved in the sedimentary record and used in several molecular proxies. We here introduce the direct, extraction-free analysis of these compounds in intact sediment core sections using laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). LDI FTICR-MS can detect the target lipids in single submillimeter-sized spots on sediment sections, equivalent to a sample mass in the nanogram range, and could thus pave the way for biomarker-based reconstruction of past environments and ecosystems at subannual to decadal resolution. We demonstrate that ratios of selected archaeal tetraethers acquired by LDI FTICR-MS are highly correlated with values obtained by conventional liquid chromatography/MS protocols. The ratio of the major archaeal lipids, caldarchaeol and crenarchaeol, analyzed in a 6.2-cm intact section of Mediterranean sapropel S1 at 250-µm resolution (∼4-y temporal resolution), provides an unprecedented view of the fine-scale patchiness of sedimentary biomarker distributions and the processes involved in proxy signal formation. Temporal variations of this lipid ratio indicate a strong influence of the ∼200-y de Vries solar cycle on reconstructed sea surface temperatures with possible amplitudes of several degrees, and suggest signal amplification by a complex interplay of ecological and environmental factors. Laser-based biomarker analysis of geological samples has the potential to revolutionize molecular stratigraphic studies of paleoenvironments. PMID:25331871

  8. Rock magnetic characterization and potential use as a high-resolution paleomagnetic recorder of fossil Porites corals in Ishigaki Island, Japan

    NASA Astrophysics Data System (ADS)

    Kumagai, Y.; Nakamura, N.; Sato, T.

    2015-12-01

    Radiocarbon (14C) is produced by the cosmic rays in the upper atmosphere and is utilized for reconstructing the past solar activity using tree rings. This 14C production is also controlled by the geomagnetic field, and the short-term (at the ~ 10-100 yr duration) movement of the geomagnetic pole to the low latitude, like geomagnetic jerks, might leads to a higher 14C production rate. In order to reconstruct the past solar activity from the 14C concentration, we should know the movement of geomagnetic pole position and the field intensity in a decadal to centennial time series. Previous reconstructions of geomagnetic paleosecular variation lack to reconstruct the short-term variation of geomagnetic field in a decadal or centennial scale. Annual banded skeletons of hermatipic corals (e.g., Porites) might possess an enormous potential as a high-resolution paleomagnetic recorder due to their continuous growths through hundreds of years at a rapid rate (up to 2 cm/yr), although usual corals show an extremely weak intensity of remanence and its low stability. Here we found that recently-ceased Porites coral skeletons thrown up on beach of the Ishigaki Island (SW Japan) possess measurable natural remanence intensities and conducted thermal and AF demagnetization of coral skeletons. The characteristic remanence directions of almost all samples are relatively stable with some fluctuations. However, some samples exhibit obviously different remanence directions from its average with calcite peaks of X-ray diffraction analysis. It is indicated that the magnetic mineral assemblage consists of a dominant biogenic-origin single-domain magnetite and a minor detrital component from FORC measurement, FMR measurement and petrological observations by FE-SEM of acid-treated residuals of our corals. Our findings suggest that Porites coral framework samples have a potential use as a high-resolution paleomagnetic recorder with careful examination of calcite content.

  9. Radio frequency phototube and optical clock: High resolution, high rate and highly stable single photon timing technique

    SciTech Connect

    Margaryan, Amur

    2011-10-01

    A new timing technique for single photons based on the radio frequency phototube and optical clock or femtosecond optical frequency comb generator is proposed. The technique has a 20 ps resolution for single photons, is capable of operating with MHz frequencies and achieving 10 fs instability level.

  10. A high-resolution record of Holocene millennial-scale oscillations of surface water, foraminiferal paleoecology and sediment redox chemistry in the SE Brazilian margin

    NASA Astrophysics Data System (ADS)

    Dias, B. B.; Barbosa, C. F.; Albuquerque, A. L.; Piotrowski, A. M.

    2014-12-01

    Holocene millennial-scale oscillations and Bond Events (Bond et al. 1997) are well reported in the North Atlantic as consequence of fresh water input and weaking of the Atlantic Meridional Overturning Circulation (AMOC). It has been hypothesized that the effect of weaking of AMOC would lead to warming in the South Atlantic due to "heat piracy", causing surface waters to warm and a reorganization of surface circulation. There are few reconstructions of AMOC strength in the South Atlantic, and none with a high resolution Holocene record of changes of productivity and the biological pump. We reconstruct past changes in the surface water mass hydrography, productivity, and sediment redox changes in high-resolution in the core KCF10-01B, located 128 mbsl water depth off Cabo Frio, Brazil, a location where upwelling is strongly linked to surface ocean hydrography. We use Benthic Foraminiferal Accumulation Rate (BFAR) to reconstruct productivity, which reveals a 1.3kyr cyclicity during the mid- and late-Holocene. The geochemistry of trace and rare earth elements on foraminiferal Fe-Mn oxide coatings show changes in redox-sensitive elements indicating that during periods of high productivity there were more reducing conditions in sediment porewaters, producing a Ce anomaly and reduction and re-precipitation of Mn oxides. Bond events 1-7 were identified by a productivity increase along with reducing sediment conditions which was likely caused by Brazil Current displacement offshore allowing upwelling of the nutritive bottom water South Atlantic Central Waters (SACW) to the euphotic zone and a stronger local biological pump. In a global context, correlation with other records show that this occurred during weakened AMOC and southward displacement of the ITCZ. We conclude that Bond climatic events and millennial-scale variability of AMOC caused sea surface hydrographic changes off the Brazilian Margin leading to biological and geochemical changes recorded in coastal records

  11. A novel method to retrieve Aerosol Optical Thickness from high-resolution optical satellite images using an extended version of the Haze Optimized Transform (HOTBAR)

    NASA Astrophysics Data System (ADS)

    Wilson, Robin; Milton, Edward; Nield, Joanna

    2016-04-01

    Aerosol Optical Thickness (AOT) data has many important applications including atmospheric correction of satellite imagery and monitoring of particulate matter air pollution. Current data products are generally available at a kilometre-scale resolution, but many applications require far higher resolutions. For example, particulate matter concentrations vary on a metre-scale, and thus data products at a similar scale are required to provide accurate assessments of particle densities and allow effective monitoring of air quality and analysis of local air quality effects on health. A novel method has been developed which retrieves per-pixel AOT values from high-resolution (~30m) satellite data. This method is designed to work over a wide range of land covers - including both bright and dark surfaces - and requires only standard visible and near-infrared data, making it applicable to a range of data from sensors such as Landsat, SPOT and Sentinel-2. The method is based upon an extension of the Haze Optimized Transform (HOT). The HOT was originally designed for assessing areas of thick haze in satellite imagery by calculating a 'haziness' value for each pixel in an image as the distance from a 'Clear Line' in feature space, defined by the high correlation between visible bands. Here, we adapt the HOT method and use it to provide AOT data instead. Significant extensions include Monte Carlo estimation of the 'Clear Line', object-based correction for land cover, and estimation of AOT from the haziness values through radiative transfer modelling. This novel method will enable many new applications of AOT data that were impossible with previously available low-resolution data, and has the potential to contribute significantly to our understanding of the air quality on health, the accuracy of satellite image atmospheric correction and the role of aerosols in the climate system.

  12. Punctuated evolution of global climate cooling during the late middle to early late Miocene: High-resolution planktonic foraminiferal and oxygen isotope records from the Mediterranean

    NASA Astrophysics Data System (ADS)

    Turco, E.; Hilgen, F. J.; Lourens, L. J.; Shackleton, N. J.; Zachariasse, W. J.

    High-resolution planktonic foraminiferal and oxygen isotope records are presented from a Mediterranean deep marine succession, dated astronomically between 12.12 and 9.78 Ma. Planktonic and benthic oxygen isotope records are punctuated by two episodes of δ18O increase, which have astronomical ages of 11.4 and 10.4 Ma and correspond to the Mi5 and Mi6 events of Miller et al. [1991a]. These ice growth events coincide with low-amplitude variations in the 1.2 Myr obliquity cycle and are accompanied by significant faunal changes in the Mediterranean, such as the arrival of neogloboquadrinids, the increase in abundance of the G. apertura-G. obliquus group, and the areal differentiation between N. atlantica and N. acostaensis. Short-term variations in the planktonic foraminiferal and oxygen isotope records correspond to dominantly precession-controlled sedimentary cycles. Features of the sapropel/gray marl layers indicate that the short-term astronomically controlled circum-Mediterranean climate changes remained basically the same over the last 12 Myr.

  13. A high-resolution Sr/Ca and [delta][sup 18]O coral record from the Great Barrier Reef, Australia, and the 1982-1983 El Nino

    SciTech Connect

    McCulloch, M.T.; Gagan, M.K.; Mortimer, G.E.; Chivas, A.R. ); Isdale, P.J. )

    1994-06-01

    A high-resolution (near weekly) Sr/Ca and oxygen isotopic record is presented for a coral from the Pandora Reef in the Great Barrier Reef (GBR) of Australia during the period of 1978 to 1984. The records are well correlated except for periods of high rainfall when river runoff has significantly modified the [delta][sup 18]O value of seawater. Using the Sr/Ca temperature calibration of De Villiers et al., the Sr/Ca records exhibit seasonally controlled cyclical SST (sea surface temperature) variations of from [approximately] 21 to [approximately] 28[degrees]C. During the very strong El Nino of 1982-1983, the Sr/CA systematics indicate a sharp drop in the winter SST to [approximately] 18.5[degrees]C. This represents a temperature anomaly of -3[degrees]C which is approximately twice that given by the [delta][sup 18]O variations, suggesting an [approximately] x2 amplification of the anomaly by the Sr/Ca system, possibly due to the increasing dominance of inorganically controlled aragonite-seawater fractionation. The oxygen isotope systematics show the combined effects of both temperature and changing seawater [delta][sup 18]O values, the latter reflecting the influx of [sup 18]O-depleted runoff during periods of high rainfall. Due to the extremely low ([approximately] 10[sup [minus]3]) Sr and Ca contents of river runoff relative to seawater, it is possible to use the Sr/Ca thermometer to calculate temperatures independent of major floods and hence deconvolve the combined effects in the oxygen isotopic record of variable temperature and the [delta][sup 18]O value of seawater. Using this approach it is possible to quantitatively reproduce the volume of runoff from the Burdekin River during the periods of major flooding that occurred in early 1979 and 1981. The results of this study demonstrate that the combined use of high-resolution Sr/Ca and [delta][sup 18]O systematics in scleractinian corals is a powerful tool for providing quantitative constraints on past climate.

  14. Detection and monitoring of early airway injury effects of half-mustard (2-chloroethylethylsulfide) exposure using high-resolution optical coherence tomography

    NASA Astrophysics Data System (ADS)

    Kreuter, Kelly A.; Mahon, Sari B.; Mukai, David S.; Su, Jianping; Jung, Woong-Gyu; Narula, Navneet; Guo, Shuguang; Wakida, Nicole; Raub, Chris; Berns, Michael W.; George, Steven C.; Chen, Zhongping; Brenner, Matthew

    2009-07-01

    Optical coherence tomography (OCT) is a noninvasive, high-resolution imaging technology capable of delivering real-time, near-histologic images of tissues. Mustard gas is a vesicant-blistering agent that can cause severe and lethal damage to airway and lungs. The ability to detect and assess airway injury in the clinical setting of mustard exposure is currently limited. The purpose of this study is to assess the ability to detect and monitor progression of half-mustard [2-chloroethylethylsulfide (CEES)] airway injuries with OCT techniques. A ventilated rabbit mustard exposure airway injury model is developed. A flexible fiber optic OCT probe is introduced into the distal trachea to image airway epithelium and mucosa in vivo. Progression of airway injury is observed over eight hours with OCT using a prototype time-domain superluminescent diode OCT system. OCT tracheal images from CEES exposed animals are compared to control rabbits for airway mucosal thickening and other changes. OCT detects the early occurrence and progression of dramatic changes in the experimental group after exposure to CEES. Histology and immunofluorescence staining confirms this finding. OCT has the potential to be a high resolution imaging modality capable of detecting, assessing, and monitoring treatment for airway injury following mustard vesicant agent exposures.

  15. Detection and monitoring of early airway injury effects of half-mustard (2-chloroethylethylsulfide) exposure using high-resolution optical coherence tomography.

    PubMed

    Kreuter, Kelly A; Mahon, Sari B; Mukai, David S; Su, Jianping; Jung, Woong-Gyu; Narula, Navneet; Guo, Shuguang; Wakida, Nicole; Raub, Chris; Berns, Michael W; George, Steven C; Chen, Zhongping; Brenner, Matthew

    2009-01-01

    Optical coherence tomography (OCT) is a noninvasive, high-resolution imaging technology capable of delivering real-time, near-histologic images of tissues. Mustard gas is a vesicant-blistering agent that can cause severe and lethal damage to airway and lungs. The ability to detect and assess airway injury in the clinical setting of mustard exposure is currently limited. The purpose of this study is to assess the ability to detect and monitor progression of half-mustard [2-chloroethylethylsulfide (CEES)] airway injuries with OCT techniques. A ventilated rabbit mustard exposure airway injury model is developed. A flexible fiber optic OCT probe is introduced into the distal trachea to image airway epithelium and mucosa in vivo. Progression of airway injury is observed over eight hours with OCT using a prototype time-domain superluminescent diode OCT system. OCT tracheal images from CEES exposed animals are compared to control rabbits for airway mucosal thickening and other changes. OCT detects the early occurrence and progression of dramatic changes in the experimental group after exposure to CEES. Histology and immunofluorescence staining confirms this finding. OCT has the potential to be a high resolution imaging modality capable of detecting, assessing, and monitoring treatment for airway injury following mustard vesicant agent exposures. PMID:19725748

  16. Detection and monitoring of early airway injury effects of half-mustard (2-chloroethylethylsulfide) exposure using high-resolution optical coherence tomography

    PubMed Central

    Kreuter, Kelly A.; Mahon, Sari B.; Mukai, David S.; Su, Jianping; Jung, Woong-Gyu; Narula, Navneet; Guo, Shuguang; Wakida, Nicole; Raub, Chris; Berns, Michael W.; George, Steven C.; Chen, Zhongping; Brenner, Matthew

    2009-01-01

    Optical coherence tomography (OCT) is a non-invasive, high-resolution imaging technology capable of delivering real-time, near-histologic images of tissues. Mustard gas is a vesicant-blistering agent that can cause severe and lethal damage to airway and lungs. The ability to detect and assess airway injury in the clinical setting of mustard exposure is currently limited. The purpose of this study is to assess the ability to detect and monitor progression of half-mustard [2-chloroethylethylsulfide (CEES)] airway injuries with OCT techniques. A ventilated rabbit mustard exposure airway injury model is developed. A flexible fiber optic OCT probe is introduced into the distal trachea to image airway epithelium and mucosa in vivo. Progression of airway injury is observed over eight hours with OCT using a prototype time-domain superluminescent diode OCT system. OCT tracheal images from CEES exposed animals are compared to control rabbits for airway mucosal thickening and other changes. OCT detects the early occurrence and progression of dramatic changes in the experimental group after exposure to CEES. Histology and immunofluorescence staining confirms this finding. OCT has the potential to be a high resolution imaging modality capable of detecting, assessing, and monitoring treatment for airway injury following mustard vesicant agent exposures. PMID:19725748

  17. High-resolution three-dimensional imaging of red blood cells parasitized by Plasmodium falciparum and in situ hemozoin crystals using optical diffraction tomography

    PubMed Central

    Kim, Kyoohyun; Yoon, HyeOk; Diez-Silva, Monica; Dao, Ming; Dasari, Ramachandra R.

    2013-01-01

    Abstract. We present high-resolution optical tomographic images of human red blood cells (RBC) parasitized by malaria-inducing Plasmodium falciparum (Pf)-RBCs. Three-dimensional (3-D) refractive index (RI) tomograms are reconstructed by recourse to a diffraction algorithm from multiple two-dimensional holograms with various angles of illumination. These 3-D RI tomograms of Pf-RBCs show cellular and subcellular structures of host RBCs and invaded parasites in fine detail. Full asexual intraerythrocytic stages of parasite maturation (ring to trophozoite to schizont stages) are then systematically investigated using optical diffraction tomography algorithms. These analyses provide quantitative information on the structural and chemical characteristics of individual host Pf-RBCs, parasitophorous vacuole, and cytoplasm. The in situ structural evolution and chemical characteristics of subcellular hemozoin crystals are also elucidated. PMID:23797986

  18. High-resolution three-dimensional imaging of red blood cells parasitized by Plasmodium falciparum and in situ hemozoin crystals using optical diffraction tomography

    NASA Astrophysics Data System (ADS)

    Kim, Kyoohyun; Yoon, HyeOk; Diez-Silva, Monica; Dao, Ming; Dasari, Ramachandra R.; Park, YongKeun

    2014-01-01

    We present high-resolution optical tomographic images of human red blood cells (RBC) parasitized by malaria-inducing Plasmodium falciparum (Pf)-RBCs. Three-dimensional (3-D) refractive index (RI) tomograms are reconstructed by recourse to a diffraction algorithm from multiple two-dimensional holograms with various angles of illumination. These 3-D RI tomograms of Pf-RBCs show cellular and subcellular structures of host RBCs and invaded parasites in fine detail. Full asexual intraerythrocytic stages of parasite maturation (ring to trophozoite to schizont stages) are then systematically investigated using optical diffraction tomography algorithms. These analyses provide quantitative information on the structural and chemical characteristics of individual host Pf-RBCs, parasitophorous vacuole, and cytoplasm. The in situ structural evolution and chemical characteristics of subcellular hemozoin crystals are also elucidated.

  19. Rewriteable optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Shull, Thomas A.; Rinsland, Pamela L.

    1991-01-01

    A NASA program to develop a high performance (high rate, high capability) rewriteable optical disk recorder for spaceflight applications is presented. An expandable, adaptable system concept is proposed based on disk Drive modules and a modular Controller. Drive performance goals are 10 gigabyte capacity are up to 1.8 gigabits per second rate with concurrent I/O, synchronous data transfer, and 2 to 5 years operating life in orbit. Technology developments, design concepts, current status, and future plans are presented.

  20. UV-laser microdissection system - A novel approach for the preparation of high-resolution stable isotope records (δ13C/δ18O) from tree rings

    NASA Astrophysics Data System (ADS)

    Schollaen, Karina; Helle, Gerhard

    2013-04-01

    Intra-annual stable isotope (δ13C and δ18O) studies of tree rings at various incremental resolutions have been attempting to extract valuable seasonal climatic and environmental information or assessing plant ecophysiological processes. For preparing high-resolution isotope samples normally wood segments or cores are mechanically divided in radial direction or cut in tangential direction. After mechanical dissection, wood samples are ground to a fine powder and either cellulose is extracted or bulk wood samples are analyzed. Here, we present a novel approach for the preparation of high-resolution stable isotope records from tree rings using an UV-laser microdissection system. Firstly, tree-ring cellulose is directly extracted from wholewood cross-sections largely leaving the wood anatomical structure intact and saving time as compared to the classical procedure. Secondly, micro-samples from cellulose cross-sections are dissected with an UV-Laser dissection microscope. Tissues of interest from cellulose cross-sections are identified and marked precisely with a screen-pen and dissected via an UV-laser beam. Dissected cellulose segments were automatically collected in capsules and are prepared for stable isotope (δ13C and δ18O) analysis. The new techniques facilitate inter- and intra-annual isotope analysis on tree-ring and open various possibilities for comparisons with wood anatomy in plant eco-physiological studies. We describe the design and the handling of this novel methodology and discuss advantages and constraints given by the example of intra-annual oxygen isotope analysis on tropical trees.

  1. Ultra-high resolution polarization-sensitive optical coherence microscopy for brain imaging at 6 um, 3.4 um and 1.3 um resolution (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Akkin, Taner; Magnain, Caroline V.; Yaseen, Mohammad A.; Cramer, Avilash; Wang, Ruopeng; Sakadžic, Sava; Boas, David A.

    2016-03-01

    Neuroanatomical pathways form the basis for functional activity of brain circuits. In the past, we developed a polarization-sensitive optical coherence tomography with serial scanning to achieve large-scale brain imaging. The system was able to visualize 3D fiber tracts of ~20 um in diameter. To investigate the neuroanatomical pathways at finer scales, we have now built a polarization-maintaining fiber based ultra-high resolution polarization-sensitive optical coherence microscope (PS-OCM) at 1300 nm. The PS-OCM has an axial resolution of 3.5 um in tissue. The detection setup consists of two spectrometers, acquiring spectral interference on orthogonal polarization channels. With a single measurement, the setup generates four contrasts: reflectivity, cross-polarization, retardance and optic axis orientation. To investigate the capability of PS-OCM at different resolutions, we used three microscope objectives that yield lateral resolutions of 6.0 um, 3.4 um and 1.3 um. Blocks of formalin fixed mouse brain and human brain were scanned. The cross-polarization and retardance images clearly depict the neuronal fiber structures, which are comparable with that generated by the maximum projection of volumetric reflectivity data. The optic axis orientation quantifies the in-plane fiber orientation. With the lateral resolution of 1.3 um, the retardance contrast is weak in white matter due to the shallow depth of focus. Overall, the ultra-high resolution PS-OCM provides a new tool to reveal neuroanatomical maps in the brain at cellular resolution.

  2. High-resolution optical spectroscopy and magnetic properties of Yb3 + in Y2SiO5

    NASA Astrophysics Data System (ADS)

    Welinski, Sacha; Ferrier, Alban; Afzelius, Mikael; Goldner, Philippe

    2016-10-01

    Rare-earth doped crystals are promising systems for quantum information processing. In particular, paramagnetic rare earths could be used to build coherent interfaces with optical and microwave photons. In addition, isotopes with nonzero nuclear spins could provide long-lived states for quantum state storage and processing. Yb3 + is particularly interesting in this respect since it is the only paramagnetic rare earth with a spin-1/2 isotope, which corresponds to the simplest possible level structure. In this paper, we report on the optical and magnetic properties of Yb3 + in the two sites of Y2SiO5 , a commonly used crystal for quantum applications. We measured optical inhomogeneous linewidths, peak absorption coefficients, oscillator strengths, and excited-state lifetimes. The Zeeman tensors were also determined in the ground and excited states, as well as the ground-state hyperfine tensor for the 3+171Yb (I =1/2 ) isotope. These results suggest that Yb3 +:Y2SiO5 is a promising material for applications like solid-state optical and microwave quantum memories.

  3. High-resolution 3-D imaging of surface damage sites in fused silica with Optical Coherence Tomography

    SciTech Connect

    Guss, G; Bass, I; Hackel, R; Mailhiot, C; Demos, S G

    2007-10-30

    In this work, we present the first successful demonstration of a non-contact technique to precisely measure the 3D spatial characteristics of laser induced surface damage sites in fused silica for large aperture laser systems by employing Optical Coherence Tomography (OCT). What makes OCT particularly interesting in the characterization of optical materials for large aperture laser systems is that its axial resolution can be maintained with working distances greater than 5 cm, whether viewing through air or through the bulk of thick optics. Specifically, when mitigating surface damage sites against further growth by CO{sub 2} laser evaporation of the damage, it is important to know the depth of subsurface cracks below the damage site. These cracks are typically obscured by the damage rubble when imaged from above the surface. The results to date clearly demonstrate that OCT is a unique and valuable tool for characterizing damage sites before and after the mitigation process. We also demonstrated its utility as an in-situ diagnostic to guide and optimize our process when mitigating surface damage sites on large, high-value optics.

  4. UAS and DTS: Using Drones and Fiber Optics to Measure High Resolution Temperature of the Atmospheric Boundary Layer

    NASA Astrophysics Data System (ADS)

    Predosa, R. A.; Darricau, B.; Higgins, C. W.

    2015-12-01

    The atmospheric boundary layer (ABL) is the lowest part of the atmosphere that directly interacts with the planet's surface. The development of the ABL plays a vital role, as it affects the transport of atmospheric constituents such as air pollutants, water vapor, and greenhouse gases. Measurements of the processes in the ABL have been difficult due to the limitations in the spatial and temporal resolutions of the equipment as well as the height of the traditional flux tower. Recent advances in the unmanned aerial vehicle (UAV) and distributed temperature sensing (DTS) technologies have provided us with new tools to study the complex processes in ABL. We conducted a series of pioneering experiments in Eastern Oregon using a platform that combines UAV and DTS to collect data during morning and evening transitions in the ABL. The major components of this platform consists of a quad-copter, a DTS computer unit, and a set of customized fiber optic cables. A total of 75 flights were completed to investigate: (1) the capability of a duplexed fiber optic cable to reduce noise in the high spatial and temporal temperature measurements taken during the morning transition; (2) the possibility of using fiber optic cable as "wet bulb" thermometer to calculate relative humidity in the ABL at high spatial and temporal resolution. The preliminary results showed that using a fiber optic cable in a duplexed configuration with the UAV-DTS platform can effectively reduce noise level during the morning transition data collection. The customized "wet bulb" fiber optic cable is capable of providing information for the calculation of relative humidity in the ABL at unprecedented spatial and temporal resolutions. From this study, the UAV-DTS platform demonstrated great potential in collecting temperature data in the ABL and with the development of atmospheric sensor technologies, it will have more applications in the future.

  5. Efficient Hardware Implementation of the Horn-Schunck Algorithm for High-Resolution Real-Time Dense Optical Flow Sensor

    PubMed Central

    Komorkiewicz, Mateusz; Kryjak, Tomasz; Gorgon, Marek

    2014-01-01

    This article presents an efficient hardware implementation of the Horn-Schunck algorithm that can be used in an embedded optical flow sensor. An architecture is proposed, that realises the iterative Horn-Schunck algorithm in a pipelined manner. This modification allows to achieve data throughput of 175 MPixels/s and makes processing of Full HD video stream (1, 920 × 1, 080 @ 60 fps) possible. The structure of the optical flow module as well as pre- and post-filtering blocks and a flow reliability computation unit is described in details. Three versions of optical flow modules, with different numerical precision, working frequency and obtained results accuracy are proposed. The errors caused by switching from floating- to fixed-point computations are also evaluated. The described architecture was tested on popular sequences from an optical flow dataset of the Middlebury University. It achieves state-of-the-art results among hardware implementations of single scale methods. The designed fixed-point architecture achieves performance of 418 GOPS with power efficiency of 34 GOPS/W. The proposed floating-point module achieves 103 GFLOPS, with power efficiency of 24 GFLOPS/W. Moreover, a 100 times speedup compared to a modern CPU with SIMD support is reported. A complete, working vision system realized on Xilinx VC707 evaluation board is also presented. It is able to compute optical flow for Full HD video stream received from an HDMI camera in real-time. The obtained results prove that FPGA devices are an ideal platform for embedded vision systems. PMID:24526303

  6. A High-Resolution Stalagmite Holocene Paleoclimate Record from Northern Venezuela with Insights into the Timing and Duration of the 8.2 ka Event

    NASA Astrophysics Data System (ADS)

    Retrum, J. B.; Gonzalez, L. A.; Edwards, R.; Cheng, H.; Tincher, S. M.; Urbani, F.

    2013-12-01

    , also suggested by Brazilian speleothem records that show trends that anti-correlate with Cueva Zarraga. The Cariaco Basin and Cueva Zarraga records show similar trends. The close proximity of Cueva Zarraga to Cariaco Basin may allow for a high-resolution tropical terrestrial and oceanic climatic response comparison.

  7. Holocene Amazon rainforest-savanna dynamics and climatic implications: high-resolution pollen record from Laguna Loma Linda in eastern Colombia

    NASA Astrophysics Data System (ADS)

    Behling, Hermann; Hooghiemstra, Henry

    2000-10-01

    We present a high-resolution pollen record of a 695-cm-long sediment core from Laguna Loma Linda, located at an altitude of 310 m in the transitional zone between the savannas of the Llanos Orientales and the Amazonian rainforest, about 100 km from the Eastern Cordillera. Based on eight AMS 14C ages, the record represents the last 8700 14C yr BP. During the period from 8700 to 6000 14C yr BP the vegetation was dominated by grass savanna with only a few woody taxa, such as Curatella and Byrsonima, present in low abundance. Gallery forest along the drainage system apparently was poorly developed. Compared with today, precipitation must have been significantly lower and seasonality stronger. During the period from 6000 to 3600 14C yr BP, rainforest taxa increased markedly, reflecting an increase in precipitation. Rainforest and gallery forest taxa such as Moraceae/Urticaceae, Melastomataceae, Alchornea, Cecropia and Acalypha, were abundant, whereas Poaceae were reduced in frequency. From 3600 to 2300 14C yr BP rainforest taxa continued to increase; Moraceae/Urticaceae became very frequent, and Myrtaceae and Myrsine became common. Savanna vegetation decreased continuously. We infer that precipitation was still increasing, and that the length of the annual dry period possibly shortened. From 2300 14C yr BP onwards, grass savanna (mainly represented by Poaceae) expanded and Mauritia palms became frequent. This reflects increased human impact on the vegetation.

  8. Normalizing XRF-scanner data: A cautionary note on the interpretation of high-resolution records from organic-rich lakes

    NASA Astrophysics Data System (ADS)

    Löwemark, L.; Chen, H.-F.; Yang, T.-N.; Kylander, M.; Yu, E.-F.; Hsu, Y.-W.; Lee, T.-Q.; Song, S.-R.; Jarvis, S.

    2011-04-01

    X-ray fluorescence (XRF) scanning of unlithified, untreated sediment cores is becoming an increasingly common method used to obtain paleoproxy data from lake records. XRF-scanning is fast and delivers high-resolution records of relative variations in the elemental composition of the sediment. However, lake sediments display extreme variations in their organic matter content, which can vary from just a few percent to well over 50%. As XRF scanners are largely insensitive to organic material in the sediment, increasing levels of organic material effectively dilute those components that can be measured, such as the lithogenic material (the closed-sum effect). Consequently, in sediments with large variations in organic material, the measured variations in an element will to a large extent mirror the changes in organic material. It is therefore necessary to normalize the elements in the lithogenic component of the sediment against a conservative element to allow changes in the input of the elements to be addressed. In this study we show that Al, which is the lightest element that can be measured using the Itrax XRF-scanner, can be used to effectively normalize the elements of the lithogenic fraction of the sediment against variations in organic content. We also show that care must be taken when choosing resolution and exposure time to ensure optimal output from the measurements.

  9. A high-resolution mid-Pleistocene temperature record from Arctic Lake El'gygytgyn: a 50 kyr super interglacial from MIS 33 to MIS 31?

    NASA Astrophysics Data System (ADS)

    de Wet, Gregory A.; Castañeda, Isla S.; DeConto, Robert M.; Brigham-Grette, Julie

    2016-02-01

    Previous periods of extreme warmth in Earth's history are of great interest in light of current and predicted anthropogenic warming. Numerous so called "super interglacial" intervals, with summer temperatures significantly warmer than today, have been identified in the 3.6 million year (Ma) sediment record from Lake El'gygytgyn, northeast Russia. To date, however, a high-resolution paleotemperature reconstruction from any of these super interglacials is lacking. Here we present a paleotemperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) from Marine Isotope Stages (MIS) 35 to MIS 29, including super interglacial MIS 31. To investigate this period in detail, samples were analyzed with an unprecedented average sample resolution of 500 yrs from MIS 33 to MIS 30. Our results suggest the entire period currently defined as MIS 33-31 (∼1114-1062 kyr BP) was characterized by generally warm and highly variable conditions at the lake, at times out of phase with Northern Hemisphere summer insolation, and that cold "glacial" conditions during MIS 32 lasted only a few thousand years. Close similarities are seen with coeval records from high southern latitudes, supporting the suggestion that the interval from MIS 33 to MIS 31 was an exceptionally long interglacial (Teitler et al., 2015). Based on brGDGT temperatures from Lake El'gygytgyn (this study and unpublished results), warming in the western Arctic during MIS 31 was matched only by MIS 11 during the Pleistocene.

  10. The Olorgesailie Drilling Project (ODP): a high-resolution drill core record from a hominin site in the East African Rift Valley

    NASA Astrophysics Data System (ADS)

    Dommain, R.; Potts, R.; Behrensmeyer, A. K.; Deino, A. L.

    2014-12-01

    The East African rift valley contains an outstanding record of hominin fossils that document human evolution over the Plio-Pleistocene when the global and regional climate and the rift valley itself changed markedly. The sediments of fossil localities typically provide, however, only short time windows into past climatic and environmental conditions. Continuous, long-term terrestrial records are now becoming available through core drilling to help elucidate the paleoenvironmental context of human evolution. Here we present a 500,000 year long high-resolution drill core record obtained from a key fossil and archeological site - the Olorgesailie Basin in the southern Kenya Rift Valley, well known for its sequence of archeological and faunal sites for the past 1.2 million years. In 2012 two drill cores (54 and 166 m long) were collected in the Koora Plain just south of Mt. Olorgesailie as part of the Olorgesailie Drilling Project (ODP) to establish a detailed climate and ecological record associated with the last evidence of Homo erectus in Africa, the oldest transition of Acheulean to Middle Stone Age technology, and large mammal species turnover, all of which are documented in the Olorgesailie excavations. The cores were sampled at the National Lacustrine Core Facility. More than 140 samples of tephra and trachytic basement lavas have led to high-precision 40Ar/39Ar dating. The cores are being analyzed for a suite of paleoclimatic and paleoecological proxies such as diatoms, pollen, fungal spores, phytoliths, ostracodes, carbonate isotopes, leaf wax biomarkers, charcoal, and clay mineralogy. Sedimentological analyses, including lithological descriptions, microscopic smear slide analysis (242 samples), and grain-size analysis, reveal a highly variable sedimentary sequence of deep lake phases with laminated sediments, diatomites, shallow lake and near shore phases, fluvial deposits, paleosols, interspersed carbonate layers, and abundant volcanic ash deposits. Magnetic

  11. Reconstructing Changes in Deep Ocean Temperature and Global Carbon Cycle during the Early Eocene Warming Trend: High-Resolution Benthic Stable Isotope Records from the SE Atlantic.

    NASA Astrophysics Data System (ADS)

    Lauretano, V.; Zachos, J. C.; Lourens, L. J.

    2014-12-01

    From the late Paleocene to the early Eocene, Earth's surface temperatures generally rose, resulting in an increase of at least 5°C in the deep ocean and culminating in the Early Eocene Climatic Optimum (EECO). This long-term warming was punctuated by a series of short-lived global warming events known as "hyperthermals", of which the Paleocene-Eocene Thermal Maximum (PETM) represents the most extreme example. At least two other short-term episodes have been identified as hyperthermals: the ETM2 (or Elmo event) at about 53.7 Myr and the ETM3 (or X-event) at about 52.5 Myr. These transient events are marked by prominent carbon isotope excursions (CIEs), recorded in marine and continental sedimentary sequences and driven by fast and massive injections of 13C-depleted carbon into the ocean-atmosphere system. Recently, evidence has indicated the presence of a regular series of hyperthermal events following the peak in temperatures of the EECO. However, continuous records are needed to investigate short- and long- term changes in the climate system throughout the Early Eocene warming trend. Here, we present new high-resolution benthic stable isotope records of the Early Eocene from ODP Site 1263, (Walvis Ridge, SE Atlantic). The carbon and oxygen records document changes in deep-sea temperature and global carbon cycle encompassing the Early Eocene hyperthermal events and the EECO interval. The transition phase to the post-EECO events is distinct by the decoupling of carbon and oxygen isotopes on the long-term scale. Spectral and wavelet analyses suggest the influence of orbital forcing, specifically long and short eccentricity cycles.

  12. Absolute optical oscillator strengths for the electronic excitation of atoms at high resolution: Experimental methods and measurements for helium

    SciTech Connect

    Chan, W.F.; Cooper, G.; Brion, C.E. )

    1991-07-01

    An alternative method is described for the measurement of absolute optical oscillator strengths (cross sections) for electronic excitation of free atoms and molecules throughout the discrete region of the valence-shell spectrum at high energy resolution (full width at half maximum of 0.048 eV). The technique, utilizing the virtual-photon field of a fast electron inelastically scattered at negligible momentum transfer, avoids many of the difficulties associated with the various direct optical techniques that have traditionally been used for absolute optical oscillator strength measurements. The method is also free of the bandwidth (line saturation) effects that can seriously limit the accuracy of photoabsorption cross-section measurements for discrete transitions of narrow linewidth obtained using the Beer-Lambert law ({ital I}{sub 0}/{ital I}=exp({ital nl}{sigma}{sub {ital p}})). Since the line-saturation effects are not widely appreciated and are only usually considered in the context of peak heights, a detailed analysis of this problem is presented, with consideration of the integrated cross section (oscillator strength) over the profile of each discrete peak.

  13. Endoscopic high-resolution auto fluorescence imaging and optical coherence tomography of airways in vivo (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pahlevaninezhad, Hamid; Lee, Anthony; Hohert, Geoffrey; Schwartz, Carley; Shaipanich, Tawimas; Ritchie, Alexander J.; Zhang, Wei; MacAulay, Calum E.; Lam, Stephen; Lane, Pierre M.

    2016-03-01

    In this work, we present multimodal imaging of peripheral airways in vivo using an endoscopic imaging system capable of co-registered optical coherence tomography and autofluorescence imaging (OCT-AFI). This system employs a 0.9 mm diameter double-clad fiber optic-based catheter for endoscopic imaging of small peripheral airways. Optical coherence tomography (OCT) can visualize detailed airway morphology in the lung periphery and autofluorescence imaging (AFI) can visualize fluorescent tissue components such as collagen and elastin, improving the detection of airway lesions. Results from in vivo imaging of 40 patients indicate that OCT and AFI offer complementary information that may increase the ability to identify pulmonary nodules in the lung periphery and improve the safety of biopsy collection by identifying large blood vessels. AFI can rapidly visualize in vivo vascular networks using fast scanning parameters resulting in vascular-sensitive imaging with less breathing/cardiac motion artifacts compared to Doppler OCT imaging. By providing complementary information about structure and function of tissue, OCT-AFI may improve site selection during biopsy collection in the lung periphery.

  14. High-resolution record of last post-glacial variations of sea-ice cover and river discharge in the western Laptev Sea (Arctic Ocean)

    NASA Astrophysics Data System (ADS)

    Stein, R. H.; Hörner, T.; Fahl, K.

    2014-12-01

    Here, we provide a high-resolution reconstruction of sea-ice cover variations in the western Laptev Sea, a crucial area in terms of sea-ice production in the Arctic Ocean and a region characterized by huge river discharge. Furthermore, the shallow Laptev Sea was strongly influenced by the post-glacial sea-level rise that should also be reflected in the sedimentary records. The sea Ice Proxy IP25 (Highly-branched mono-isoprenoid produced by sea-ice algae; Belt et al., 2007) was measured in two sediment cores from the western Laptev Sea (PS51/154, PS51/159) that offer a high-resolution composite record over the last 18 ka. In addition, sterols are applied as indicator for marine productivity (brassicasterol, dinosterol) and input of terrigenous organic matter by river discharge into the ocean (campesterol, ß-sitosterol). The sea-ice cover varies distinctly during the whole time period and shows a general increase in the Late Holocene. A maximum in IP25 concentration can be found during the Younger Dryas. This sharp increase can be observed in the whole circumarctic realm (Chukchi Sea, Bering Sea, Fram Strait and Laptev Sea). Interestingly, there is no correlation between elevated numbers of ice-rafted debris (IRD) interpreted as local ice-cap expansions (Taldenkova et al. 2010), and sea ice cover distribution. The transgression and flooding of the shelf sea that occurred over the last 16 ka in this region, is reflected by decreasing terrigenous (riverine) input, reflected in the strong decrease in sterol (ß-sitosterol and campesterol) concentrations. ReferencesBelt, S.T., Massé, G., Rowland, S.J., Poulin, M., Michel, C., LeBlanc, B., 2007. A novel chemical fossil of palaeo sea ice: IP25. Organic Geochemistry 38 (1), 16e27. Taldenkova, E., Bauch, H.A., Gottschalk, J., Nikolaev, S., Rostovtseva, Yu., Pogodina, I., Ya, Ovsepyan, Kandiano, E., 2010. History of ice-rafting and water mass evolution at the northern Siberian continental margin (Laptev Sea) during Late

  15. Two recent surtseyan eruptions in the Zubair archipelago (Red Sea) studied using high-resolution radar and optical satellite remote sensing

    NASA Astrophysics Data System (ADS)

    Xu, Wenbin; Jónsson, Sigurjón

    2014-05-01

    The birth and growth of new volcanic islands are rare and spectacular geological events that are far from being fully understood. The recent Surtseyan eruptions in the Zubair archipelago, southern Red Sea, from December 2011 to January 2012 as well as between September and November 2013, formed two new oceanic islands and thus provided an exceptional opportunity to study magma-ocean interaction, new-island formation and evolution, as well as coastal erosion. However, no in-situ ground-based geophysical or geodetic measurements were obtained during these eruptions, and we therefore use multiple optical satellite imagery from several different satellites (Ali, Landsat 7&8, Quickbird and WorldView-2) together with high-resolution TerraSAR-X and TanDEM-X radar data to study the volcanic eruptions and how the islands evolved during and after the eruptive activity. The optical images show explosive activity during both eruptions, with a thick white plumes and black tephra rising from the eruptive vents. The images also reveal that the 2011-12 eruption began on ~19 December 2012, was fed from a short NW-SE fissure, and that it ended between 9 and 12 January 2012. The 2011-12 eruption formed a new island that consists of a single elongated cone, oriented approximately parallel to the axis of the Red Sea rift. The 2013 eruption started on 28 September 2013 and went by mostly unnoticed. It lasted both longer (about two months) and formed a larger island, than the 2011-12 eruption. Time series of optical images reveal that significant wind and coastal erosion, as well as possible landslide activity has resulted in changes of both the size and the shape of the two new islands. Regular high-resolution TerraSAR-X satellite acquisitions of the area did not start until on 20 January 2012. These data could provide information about post-eruption deformation associated with the new deposits, but the coherence is not very good on the island formed in the first eruption. However, we

  16. Ultra-high-resolution large-dynamic-range optical fiber static strain sensor using Pound-Drever-Hall technique.

    PubMed

    Liu, Qingwen; Tokunaga, Tomochika; He, Zuyuan

    2011-10-15

    We report the realization of a fiber-optic static strain sensor with ultrahigh resolution and large dynamic range for the applications of geophysical research. The sensor consists of a pair of fiber-Bragg-grating-based Fabry-Perot interferometers as sensor heads for strain sensing and reference, respectively. The Pound-Drever-Hall technique is employed to interrogate the sensor heads, and a cross-correlation algorithm is used to figure out the strain information with high precision. Static strain resolution down to 5.8 nanostrains is demonstrated. The dynamic range can be extended up to hundreds of microstrains, and the measuring period is a few tens of seconds.

  17. Preclinical evaluation and intraoperative human retinal imaging with a high-resolution microscope-integrated spectral domain optical coherence tomography device

    PubMed Central

    Hahn, Paul; Migacz, Justin; O’Connell, Rachelle; Day, Shelley; Lee, Annie; Lin, Phoebe; Vann, Robin; Kuo, Anthony; Fekrat, Sharon; Mruthyunjaya, Prithvi; Postel, Eric A.; Izatt, Joseph A.; Toth, Cynthia A.

    2013-01-01

    Purpose We have recently developed a high-resolution microscope-integrated spectral domain optical coherence tomography (MIOCT) device designed to enable OCT acquisition simultaneous with surgical maneuvers. The purpose of this report is to describe translation of this device from preclinical testing into human intraoperative imaging. Methods Prior to human imaging, surgical conditions were fully simulated for extensive preclinical MIOCT evaluation in a custom model eye system. MIOCT images were then acquired in normal human volunteers and during vitreoretinal surgery in patients who consented to participate in a prospective Institutional Review Board-approved study. MIOCT images were obtained before and at pauses in surgical maneuvers and were compared based on pre-determined diagnostic criteria to images obtained with a high-resolution research handheld spectral domain OCT system (HHOCT, Bioptigen Inc., Research Triangle Park, NC) at the same time point. Cohorts of five consecutive patients were imaged. Successful endpoints were pre-defined, including ≥80% correlation in identification of pathology between MIOCT and HHOCT in ≥80% of patients. Results MIOCT was favorably evaluated by study surgeons and scrub nurses, all of whom responded that they would consider participating in human intraoperative imaging trials. The preclinical evaluation identified significant improvements that were made prior to MIOCT use during human surgery. The MIOCT transition into clinical human research was smooth. MIOCT imaging in normal human volunteers demonstrated high-resolution comparable to tabletop scanners. In the operating room, after an initial learning curve, surgeons successfully acquired human macular MIOCT images before and after surgical maneuvers. MIOCT imaging confirmed preoperative diagnoses, such as full-thickness macular hole and vitreomacular traction, and demonstrated post-surgical changes in retinal morphology. Two cohorts of five patients were imaged. In the

  18. A real-time ARMS PCR/high-resolution melt curve assay for the detection of the three primary mitochondrial mutations in Leber’s hereditary optic neuropathy

    PubMed Central

    Ryan, Fergus; O’Dwyer, Veronica; Neylan, Derek

    2016-01-01

    Purpose Approximately 95% of patients who are diagnosed with Leber’s hereditary optic neuropathy (LHON) have one of three mitochondrial point mutations responsible for the disease, G3460A, G11778A, and T14484C. The purpose of this study was to develop a novel multiplex real-time amplification-refractory mutation system (ARMS) PCR combined with high-resolution melt curves to identify the individual mutations involved. The study aimed to provide a more robust, cost- and time-effective mutation detection strategy than that offered with currently available methods. The assay reported in this study will allow diagnostic laboratories to avoid costly next-generation sequencing (NGS) assays for most patients with LHON and to focus resources on patients with unknown mutations that require further analysis. Methods The test uses a combination of multiplex allele-specific PCR (ARMS PCR) in combination with a high-resolution melt curve analysis to detect the presence of the mutations in G3460A, G11778A, and T14484C. PCR primer sets were designed to produce a control PCR product and PCR products only in the presence of the mutations in 3460A, 11778A, and 14484C in a multiplex single tube format. Products produce discrete well-separated melt curves to clearly detect the mutations. Results This novel real-time ARMS PCR/high-resolution melt curve assay accurately detected 95% of the mutations that cause LHON. The test has proved to be robust, cost- and time-effective with the real-time closed tube system taking approximately 1 h to complete. Conclusions A novel real-time ARMS PCR/high-resolution melt curve assay is described for the detection of the three primary mitochondrial mutations in LHON. This test provides a simple, robust, easy-to-read output that is cost- and time-effective, thus providing an alternative method to individual endpoint PCR-restriction fragment length polymorphism (RFLP), PCR followed by Sanger sequencing or pyrosequencing, and next-generation sequencing

  19. Punctuated Evolution of Global Climate Cooling during the late Middle to early Late Miocene: High-Resolution Planktonic Foraminiferal and Oxygen Isotope Records from the Mediterranean

    NASA Astrophysics Data System (ADS)

    Turco, E.; Hilgen, F. J.; Lourens, L. J.; Shackleton, N. J.; Zachariasse, W. J.; Kruk, R. W.

    2001-05-01

    High-resolution planktonic foraminiferal and oxygen isotope records are presented from a deep marine succession of late Middle to early Late Miocene age in the Mediterranean, dated astronomically between 12.12 and 9.78 Ma. Long-term changes in the faunal composition reflect the overall late Neogene cooling trend. The planktonic and benthic oxygen isotope records are punctuated by two episodes of δ 18O increase, which have astronomical ages of 11.4 and 10.4 Ma and correspond to the Mi5 and Mi6 events of Miller et al. (1991a). The first-order comparison with the astronomical time series for the variations in the tilt of the Earth's axis revealed that these ice growth events coincide with low amplitude variations in the 1.2 myr obliquity cycle. This phase relation is different from that found during the last 5 myr, pointing to a fundamentally different response of the ice sheets to long-term obliquity induced variations in insolation. The inferred global cooling during Mi5 and Mi6 is accompanied by significant faunal changes in the Mediterranean, such as the arrival of neogloboquadrinids, the increase in abundance of the G. apertura-G. obliquus group, and the areal differentiation between N. atlantica and N. acostaensis. Other faunal events, such as the disappearance of P. mayeri and the coiling changes in neogloboquadrinids are not related to these glacial episodes, but may have been controlled by short-term climate fluctuations superimposed on long-term astronomically and/or tectonically induced climate changes. Short-term variations in the planktonic foraminiferal and oxygen isotope records correspond to dominantly precession-controlled sedimentary cycles. The micropaleontological and stable isotopic features of sapropel/grey marl layers are identical to those observed for Late Miocene to Pleistocene sapropels, indicating that the short-term astronomically controlled circum-Mediterranean climate changes remained basically the same over the last 12 myr.

  20. A High-Resolution Multi-Proxy Lake Sediment Record from Torfdalsvatn Suggests an Enhanced Temperature Gradient Between North and South Iceland During the Early Holocene

    NASA Astrophysics Data System (ADS)

    Florian, Christopher; Geirsdóttir, Áslaug; Miller, Gifford; Axford, Yarrow

    2015-04-01

    enhanced climate gradient between south and north Iceland during much of the Holocene. A comparison of the data from this core with other high-resolution regional climate records can lead to a better understanding of the relationship between marine and terrestrial climate, as well as the differences in climate histories between north and south Iceland.

  1. Clumped Isotope Verification of δ18O-Based Freshwater Mussel Shell Growth Chronology for a High-Resolution Climate and River Discharge Record

    NASA Astrophysics Data System (ADS)

    VanPlantinga, A.; Grossman, E. L.; Passey, B. H.; Randklev, C.

    2015-12-01

    Isotope profiles in freshwater mussel shells can be used to reconstruct climate, water source, and river discharge, but problems arise from variable water temperature and δ18O. To resolve this complexity and expand the application of isotope sclerochronology to the study of past river systems, we measured δ18O and Δ47 in two common freshwater mussel species from the Brazos River in Texas. To compare the environmental record with the shell record and develop a sclerochronology, weekly water temperature and δ18O data were collected from the Brazos River near College Station from January 2012 to August 2013. The river data reveal complex, irregular patterns for predicted aragonite δ18O. Comparing δ18O profiles from micromilled transects (70-200 µm increments) of coeval shell growth within and between shells yielded consistent patterns. Shell δ18O can be accurately matched to predicted δ18O, providing a chronology of shell growth. However, without a water temperature and δ18O record, interpreting a sclerochronology would be impossible. Shell Δ47 can potentially provide a seasonal chronology to verify the δ18O sclerochronology, which would be invaluable for the use of δ18O sclerochronology in historical and ancient shells. For Δ47 analyses, samples were taken at 0.5 mm resolution in presumed seasonal dark and light growth bands. Clumped temperatures range between 21 and 35 ± 4˚C (Henkes et al., 2013) and track the river temperature record, supporting the interpreted shell δ18O chronology. Shell Δ47-calculated water δ18O values range from -1.2 to 1.5 ± 0.9‰ and match river δ18O. High-resolution shell δ18O profiles combined with Δ47 temperatures can reconstruct a weekly history of water δ18O, and with the observed river discharge vs. water δ18O relation, produce a qualitative record of river discharge. These analytical techniques applied to a historical Brazos River mussel shell collected prior to dam construction reveal weekly records of

  2. Long-haul and high-resolution optical time domain reflectometry using superconducting nanowire single-photon detectors

    PubMed Central

    Zhao, Qingyuan; Xia, Lan; Wan, Chao; Hu, Junhui; Jia, Tao; Gu, Min; Zhang, Labao; Kang, Lin; Chen, Jian; Zhang, Xuping; Wu, Peiheng

    2015-01-01

    In classical optical time domain reflectometries (OTDRs), for sensing an 200-km-long fiber, the optical pulses launched are as wide as tens of microseconds to get enough signal-to-noise ratio, while it results in a two-point resolution of kilometers. To both reach long sensing distance and sub-kilometer resolution, we demonstrated a long-haul photon-counting OTDR using a superconducting nanowire single-photon detector. In a 40-minute-long measurement, we obtained a dynamic range of 46.9 dB, corresponding to a maximum sensing distance of 246.8 km, at a two-point resolution of 0.1 km. The time for measuring fiber after 100 km was reduced to one minute, while the fiber end at 217 km was still distinguished well from noise. After reducing the pulse width to 100 ns, the experimental two-point resolution was improved to 20 m while the maximum sensing distance was 209.47 km. PMID:26020163

  3. High resolution record of millet cultivation during the Bronze Age around Lake le Bourget (French Alps). Is there any climatic control?

    NASA Astrophysics Data System (ADS)

    Jacob, J.; Disnar, J. R.; Arnaud, F.; Billaud, Y.; Chapron, E.; Sicre, M.-A.; Boscardin, R.

    2009-04-01

    Our understanding of past interactions between the development of human societies, the evolution of climate and associated changes in ecosystems and landscape dynamics is conditioned by the acquisition of high resolution records within which specific tracers allow us estimating variability. The recent development of a molecular biomarker (miliacin) specific of Panicum miliaceum (common millet) associated with the determination of a biomarker allowing to track soil erosion in the sediments of Lake le Bourget (French Alps; [1], [2]) expands the possibilities afforded by organic geochemistry applied to sedimentary archives to unravel these interactions. Within the frame of the Pygmalion project (ANR Blanc, France) we improved the previous miliacin record from Lake le Bourget sediments [1] to reach an infra-decadal resolution for the 2000-600 BC time period that covers the Bronze Age. Miliacin is detected for the first time in sediment samples dated back to ca. 1700 BC, in agreement with the supposed date of introduction of P. miliaceum in the region. Miliacin concentration is low (ca. 20 ng.g-1) during the 1700-1400 BC interval and then rises to values up to 300 ng.g-1 at 850 BC before the strong decrease to 20 ng.g-1 at 750 BC imputable to the abandonment of palaffitic habitats due to a climatic deterioration at the Bronze Age/Iron Age transition. In addition to this general trend, miliacin concentration shows century-scale variations in the 1700-800 BC interval that share similarities with other records. Two periods of miliacin high concentrations at 950 and 850 BC coincide with high densities of dendrochronological dates acquired on wooden piles and with two periods of lake level lowering. The comparison of miliacin evolution in Lake le Bourget with the high resolution alkenone-derived sea surface temperature (SST) record obtained in the North Atlantic off Iceland [3] shows striking coincidences. Previous studies showed that periods of elevated SSTs in this area

  4. Detecting Rock Glacier Dynamics in Southern Carpathians Mountains Using High-Resolution Optical and Multi-Temporal SAR Satellite Imagery .....

    NASA Astrophysics Data System (ADS)

    Necsoiu, M.; Onaca, A.

    2015-12-01

    This research provided the first documented assessment of the dynamics of rock glaciers in Southern Carpathian Mountains over almost half a century (1968-2014). The dynamics of four representative rock glaciers were assessed using complementary satellite-based optical and radar remote sensing techniques. We investigated the dynamics of the area using co-rectification of paired optical satellite datasets acquired by SPOT5, WV-1, Pléiades, and Corona to estimate short term (7 years) and longer term changes (44 years). Accurately rectifying and co-registering Corona KH-4B imagery allowed us to expand the time horizon over which changes in this alpine environment could be analyzed. The displacements revealed by this analysis correlate with variations in local slope of the rock glaciers, and presence or absence of permafrost. For radar analysis, nine ascending ALOS-1 PALSAR images were used based clear sky and absence of snow groundcover (i.e. June-October). Although decorrelation limits the ability to perform quantitative InSAR analyses, loss of coherence was useful in detecting subtle changes in active rock glacier environments, as well as other mass movements including rock falls, rock avalanches, debris flows, creep of permafrost, and solifluction. Small Baseline Subset (SBAS) InSAR analysis successfully quantified rates of change for unstable areas. The results of this investigation, although based on limited archived imagery, demonstrate that correlation analysis, coherence analysis, and multitemporal InSAR techniques can yield useful information for detecting creeping permafrost in a complex mountain environment, such as Retezat Mountains. Our analyses showed that rock glaciers in the Southern Carpathian Mountains are experiencing very slow annual movement of only a few cm per year. Results of the remote sensing analyses are consistent with field observations of permafrost occurrence at these sites (for more, please see Abstract ID# 68413). The combined optical

  5. High-resolution spectrally-resolved fiber optic sensor interrogation system based on a standard DWDM laser module.

    PubMed

    Njegovec, Matej; Donlagic, Denis

    2010-11-01

    This paper presents a spectrally-resolved integration system suitable for the reading of Bragg grating, all-fiber Fabry-Perot, and similar spectrally-resolved fiber-optic sensors. This system is based on a standard telecommunication dense wavelength division multiplexing transmission module that contains a distributed feedback laser diode and a wavelength locker. Besides the transmission module, only a few additional opto-electronic components were needed to build an experimental interrogation system that demonstrated over a 2 nm wide wavelength interrogation range, and a 1 pm wavelength resolution. When the system was combined with a typical Bragg grating sensor, a strain resolution of 1 με and temperature resolution of 0.1 °C were demonstrated experimentally. The proposed interrogation system relies entirely on Telecordia standard compliant photonic components and can thus be straightforwardly qualified for use within the range of demanding applications.

  6. Optical Sectioning and High Resolution in Single-Slice Structured Illumination Microscopy by Thick Slice Blind-SIM Reconstruction.

    PubMed

    Jost, Aurélie; Tolstik, Elen; Feldmann, Polina; Wicker, Kai; Sentenac, Anne; Heintzmann, Rainer

    2015-01-01

    The microscope image of a thick fluorescent sample taken at a given focal plane is plagued by out-of-focus fluorescence and diffraction limited resolution. In this work, we show that a single slice of Structured Illumination Microscopy (two or three beam SIM) data can be processed to provide an image exhibiting tight sectioning and high transverse resolution. Our reconstruction algorithm is adapted from the blind-SIM technique which requires very little knowledge of the illumination patterns. It is thus able to deal with illumination distortions induced by the sample or illumination optics. We named this new algorithm thick slice blind-SIM because it models a three-dimensional sample even though only a single two-dimensional plane of focus was measured.

  7. Optical Sectioning and High Resolution in Single-Slice Structured Illumination Microscopy by Thick Slice Blind-SIM Reconstruction.

    PubMed

    Jost, Aurélie; Tolstik, Elen; Feldmann, Polina; Wicker, Kai; Sentenac, Anne; Heintzmann, Rainer

    2015-01-01

    The microscope image of a thick fluorescent sample taken at a given focal plane is plagued by out-of-focus fluorescence and diffraction limited resolution. In this work, we show that a single slice of Structured Illumination Microscopy (two or three beam SIM) data can be processed to provide an image exhibiting tight sectioning and high transverse resolution. Our reconstruction algorithm is adapted from the blind-SIM technique which requires very little knowledge of the illumination patterns. It is thus able to deal with illumination distortions induced by the sample or illumination optics. We named this new algorithm thick slice blind-SIM because it models a three-dimensional sample even though only a single two-dimensional plane of focus was measured. PMID:26147644

  8. Characterization of an improved polyimide-etalon all-optical transducer for high-resolution ultrasound imaging.

    PubMed

    Sheaff, Clay; Ashkenazi, Shai

    2014-07-01

    All-optical transduction of ultrasound provides high-frequency (>20 MHz) operation in the absence of electrical noise and distortion that hinders small-scale piezoelectric probes. Although fabrication of an all-optical 2-D array suitable for in vivo imaging remains incomplete, a thin-film structure integrating a polyimide film with a Fabry-Perot (etalon) receiver has been shown to be a viable candidate. We present here incremental improvements in the performance of a polyimide-etalon transducer and demonstrate imaging with an array configuration alternative to our previous study. We first show that a gain of more than 30% in output pressure is achieved when increasing the thickness of a bare polyimide film from 3 to 15 μm. This motivated the choice of polyimide as the etalon medium--a configuration made possible by utilizing a dielectric mirror that transmits wavelengths used for generation of ultrasound (ultraviolet) and reflects those for detection (near infrared). The increased reflectivity of the dielectric mirror resulted in a 2-fold decrease in noise-equivalent pressure to 3.3 kPa over a bandwidth of 47.5 MHz (0.48 Pa/√Hz). The transmit/receive center frequency increased from 37 to 49 MHz with a -6-dB bandwidth of 126%, and a maximum pressure of 213 kPa was produced using a 43 μm UV spot. A 2 x 2 mm synthetic array of 957 transmitters centered on a 1 x 1 mm synthetic array of four receivers was used to image two wire targets. Offline reconstruction indicated lateral resolutions of 70 and 114 μm at depths of 2.4 and 5.8 mm, respectively, with an average axial resolution of 35 μm. Finally, we explore the challenges of imaging in this configuration, which provides the best opportunity for real-time performance pending further development. PMID:24960711

  9. High-resolution fiber optic microscopy with fluorescent contrast enhancement for the identification of axillary lymph node metastases in breast cancer: a pilot study.

    PubMed

    Rosbach, Kelsey J; Shin, Dongsuk; Muldoon, Timothy J; Quraishi, Mohammad A; Middleton, Lavinia P; Hunt, Kelly K; Meric-Bernstam, Funda; Yu, Tse-Kuan; Richards-Kortum, Rebecca R; Yang, Wei

    2010-01-01

    This prospective pilot study evaluates the potential of high-resolution fiber optic microscopy (HRFM) to identify lymph node metastases in breast cancer patients. 43 lymph nodes were collected from 14 consenting breast cancer patients. Proflavine dye was topically applied to lymph nodes ex vivo to allow visualization of nuclei. 242 images were collected at 105 sites with confirmed histopathologic diagnosis. Quantitative statistical features were calculated from images, assessed with one-way ANOVA, and were used to develop a classification algorithm with the goal of objectively discriminating between normal and metastatic tissue. A classification algorithm using mean image intensity and skewness achieved sensitivity of 79% (27/34) and specificity of 77% (55/71). This study demonstrates the technical feasibility and diagnostic potential of HRFM with fluorescent contrast in the ex vivo evaluation of lymph nodes from breast cancer patients. PMID:21258518

  10. Design Concept for a High-Resolution Variable Included Angle Grazing Incidence Monochromator with a Varied Line Spacing Grating and a New Optics for Microfocusing

    SciTech Connect

    Amemiya, Kenta; Abe, Hitoshi; Miyawaki, Jun; Sako, Erika O.; Ohta, Toshiaki

    2007-01-19

    A novel design concept for a variable included angle Monk-Gillieson mounting monochromator with a varied line spacing grating is presented and the energy resolution is estimated by using the ray-tracing method. It is indicated that relatively high resolution is achieved even if one scans the photon energy with a fixed included angle. A novel microfocusing system, two-step Kirkpatric-Baez optics, is also proposed. The ray tracing results indicate that a submicron spot size in FWHM is achieved by focusing mirrors with commercially available slope errors at a relatively long working distance. Preliminary results from a prototype system for microfocusing are demonstrated, which shows that a spot size of several {mu}m can be achieved by using cylindrical mirrors only.

  11. High-resolution record of the Matuyama-Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia.

    PubMed

    Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

    2011-12-01

    A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama-Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands' lavas, which have a mean (40)Ar/(39)Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area.

  12. High-resolution record of the Matuyama–Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia

    PubMed Central

    Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

    2011-01-01

    A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama–Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands’ lavas, which have a mean 40Ar/39Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area. PMID:22106291

  13. A high-resolution diatom-inferred palaeoconductivity and lake level record of the Aral Sea for the last 1600 yr

    NASA Astrophysics Data System (ADS)

    Austin, Patrick; Mackay, Anson; Palagushkina, Olga; Leng, Melanie

    2007-05-01

    Formerly the world's fourth largest lake by area, the Aral Sea is presently undergoing extreme desiccation due to large-scale irrigation strategies implemented in the Soviet era. As part of the INTAS-funded CLIMAN project into Holocene climatic variability and the evolution of human settlement in the Aral Sea basin, fossil diatom assemblages contained within a sediment core obtained from the Aral Sea have been applied to a diatom-based inference model of conductivity ( r2 = 0.767, RMSEP = 0.469 log 10 μS cm - 1). This has provided a high-resolution record of conductivity and lake level change over the last ca. 1600 yr. Three severe episodes of lake level regression are indicated at ca. AD 400, AD 1195-1355 and ca. AD 1780 to the present day. The first two regressions may be linked to the natural diversion of the Amu Darya away from the Aral Sea and the failure of cyclones formed in the Mediterranean to penetrate more continental regions. Human activity, however, and in particular the destruction of irrigation facilities are synchronous with these early regressions and contributed to the severity of the observed low stands.

  14. Perturbation of the carbon cycle during the late Pliensbachian - early Toarcian: New insight from high-resolution carbon isotope records in Morocco

    NASA Astrophysics Data System (ADS)

    Bodin, Stéphane; Krencker, Francois-Nicolas; Kothe, Tim; Hoffmann, René; Mattioli, Emanuela; Heimhofer, Ulrich; Kabiri, Lahcen

    2016-04-01

    Preceding the early Toarcian Oceanic Anoxic Event by ∼1 Myr, the Pliensbachian-Toarcian boundary event is in many aspects as severe and disturbing for the environment as its better-studied successor. Both events are associated with rapid and pronounced global warming, major faunal and floral turnover, increased hydrological cycling and dramatic collapses of carbonate production. To better characterize the Pliensbachian-Toarcian boundary event, a high-resolution, paired carbonate and organic matter carbon isotope survey of three sections from the Central High Atlas Basin of Morocco has been undertaken. A pronounced negative shift in the carbonate carbon-isotope record, not paralleled by a similar excursion in the organic carbon, can be linked to the collapse of the neritic carbonate factory in the earliest Toarcian. These results show that, contrary to the Toarcian Oceanic Anoxic Event, a rapid and massive injection of 13C-depleted carbon into the atmosphere is not responsible for the environmental perturbations observed during the Pliensbachian-Toarcian boundary event. However, input of isotopically non-depleted carbon such as mantle source CO2 into the atmosphere as a potential cause for the Pliensbachian-Toarcian boundary event cannot be excluded. This would most probably be sourced from an early pulse of the Karoo-Ferrar Large Igneous Province.

  15. Very high resolution long-baseline water-tube tiltmeter to record small signals from Earth free oscillations up to secular tilts

    NASA Astrophysics Data System (ADS)

    d'Oreye, Nicolas F.; Zürn, Walter

    2005-02-01

    A 43m long floatless water-tube tiltmeter has been in operation since 1997 at the Walferdange Underground Laboratory for Geodynamics in the Grand Duchy of Luxembourg. The absence of moving parts makes this instrument particularly simple but does not prevent it from measuring some very small geophysical signals such as the Earth tides with a very favorable signal-to-noise ratio or the successive passages of Love waves circling the globe after major Earthquakes. Its very low noise level and its high resolution up to the long-period seismic band (where for instance the resolution is better than 5×10-12rad) also allows the successful recording of rarely observed grave toroidal and spheroidal free oscillations of the Earth excited by major earthquakes. In the environmental conditions of its installation (in a gypsum mine at 100m depth), the instrument shows a high degree of reliability and a very low drift rate (<0.005microrad/month). The analytical tilt and horizontal displacement transfer functions computed for this instrument and its sensors can be used to calculate the best geometrical characteristics for the construction of prototypes which should respond to specific requirements for applications in geophysics or geotechnics.

  16. High-resolution record of the Matuyama-Brunhes transition constrains the age of Javanese Homo erectus in the Sangiran dome, Indonesia.

    PubMed

    Hyodo, Masayuki; Matsu'ura, Shuji; Kamishima, Yuko; Kondo, Megumi; Takeshita, Yoshihiro; Kitaba, Ikuko; Danhara, Tohru; Aziz, Fachroel; Kurniawan, Iwan; Kumai, Hisao

    2011-12-01

    A detailed paleomagnetic study conducted in the Sangiran area, Java, has provided a reliable age constraint on hominid fossil-bearing formations. A reverse-to-normal polarity transition marks a 7-m thick section across the Upper Tuff in the Bapang Formation. The transition has three short reversal episodes and is overlain by a thick normal polarity magnetozone that was fission-track dated to the Brunhes chron. This pattern closely resembles another high-resolution Matuyama-Brunhes (MB) transition record in an Osaka Bay marine core. In the Sangiran sediments, four successive transitional polarity fields lie just below the presumed main MB boundary. Their virtual geomagnetic poles cluster in the western South Pacific, partly overlapping the transitional virtual geomagnetic poles from Hawaiian and Canary Islands' lavas, which have a mean (40)Ar/(39)Ar age of 776 ± 2 ka. Thus, the polarity transition is unambiguously the MB boundary. A revised correlation of tuff layers in the Bapang Formation reveals that the hominid last occurrence and the tektite level in the Sangiran area are nearly coincident, just below the Upper Middle Tuff, which underlies the MB transition. The stratigraphic relationship of the tektite level to the MB transition in the Sangiran area is consistent with deep-sea core data that show that the meteorite impact preceded the MB reversal by about 12 ka. The MB boundary currently defines the uppermost horizon yielding Homo erectus fossils in the Sangiran area. PMID:22106291

  17. Connecting the Final Drainage of Lake Agassiz to the 8.2 ka Event by Means of a High- Resolution Sea-Level Record From the Mississippi Delta

    NASA Astrophysics Data System (ADS)

    Li, Y.; Tornqvist, T. E.; Nevitt, J. M.; Shen, Z.; Yu, S.

    2008-12-01

    The catastrophic drainage of proglacial lakes Agassiz and Ojibway (LAO) in the early Holocene is widely believed to have triggered the 8.2 ka cold event. The timing of the LAO drainage, however, remains poorly constrained, which impedes our understanding of the abruptness of this climate change in response to a rapid freshwater forcing. Dating of the LAO drainage in the Hudson Bay area (Barber et al., 1999) yielded an age of 8.47 ± 0.30 ka, thus leaving large uncertainties about its connection with the 8.2 ka event. Here we refine the chronology of the final LAO drainage by constructing a high-resolution sea-level record from the Mississippi Delta with the basal peat approach. Two separate basal peat beds are interpreted to bracket an abrupt sea-level rise around 8.2 ka. The stratigraphically deeper level (Level A) contains a 2 cm basal peat layer that is abruptly overlain by Rangia cuneata- bearing lagoonal muds, representing the onset of an abrupt sea-level rise. The stratigraphically shallower level (Level B) contains a 6 cm basal peat layer that is covered by organic-rich muds, representing the end of the abrupt sea-level rise. Radiocarbon dating of different fractions of macrofossils from each peat layer yields consistent ages. The peat layer from Level A and the base of the peat layer from Level B yield ages of 8257 Cal. yr BP (median age with 2 sigma range of 8198-8270) and 8258 Cal. yr BP (median age with 2 sigma range of 8198-8270), respectively. The indistinguishable ages from these two peat layers, together with the diagnostic stratigraphic features, confirms that sea-level rise was likely instantaneous. This new chronology of the final LAO drainage is similar to the timings of the onset of the 8.2 ka event determined from high-resolution studies of Greenland ice cores and an Omani stalagmite, suggesting an instantaneous ocean-atmospheric system response to freshwater forcing, consistent with model predictions.

  18. Optical coherence tomography guided microinjections in live mouse embryos: high-resolution targeted manipulation for mouse embryonic research

    NASA Astrophysics Data System (ADS)

    Syed, Saba H.; Coughlin, Andrew J.; Garcia, Monica D.; Wang, Shang; West, Jennifer L.; Larin, Kirill V.; Larina, Irina V.

    2015-05-01

    The ability to conduct highly localized delivery of contrast agents, viral vectors, therapeutic or pharmacological agents, and signaling molecules or dyes to live mammalian embryos is greatly desired to enable a variety of studies in the field of developmental biology, such as investigating the molecular regulation of cardiovascular morphogenesis. To meet such a demand, we introduce, for the first time, the concept of employing optical coherence tomography (OCT)-guide microinjections in live mouse embryos, which provides precisely targeted manipulation with spatial resolution at the micrometer scale. The feasibility demonstration is performed with experimental studies on cultured live mouse embryos at E8.5 and E9.5. Additionally, we investigate the OCT-guided microinjection of gold-silica nanoshells to the yolk sac vasculature of live cultured mouse embryos at the stage when the heart just starts to beat, as a potential approach for dynamic assessment of cardiovascular form and function before the onset of blood cell circulation. Also, the capability of OCT to quantitatively monitor and measure injection volume is presented. Our results indicate that OCT-guided microinjection could be a useful tool for mouse embryonic research.

  19. Using high-resolution satellite aerosol optical depth to estimate daily PM2.5 geographical distribution in Mexico City

    PubMed Central

    Just, Allan C.; Wright, Robert O.; Schwartz, Joel; Coull, Brent A.; Baccarelli, Andrea A.; Tellez-Rojo, Martha María; Moody, Emily; Wang, Yujie; Lyapustin, Alexei; Kloog, Itai

    2015-01-01

    Recent advances in estimating fine particle (PM2.5) ambient concentrations use daily satellite measurements of aerosol optical depth (AOD) for spatially and temporally resolved exposure estimates. Mexico City is a dense megacity that differs from other previously modeled regions in several ways: it has bright land surfaces, a distinctive climatological cycle, and an elevated semi-enclosed air basin with a unique planetary boundary layer dynamic. We extend our previous satellite methodology to the Mexico City area, a region with higher PM2.5 than most US and European urban areas. Using a novel 1 km resolution AOD product from the MODIS instrument, we constructed daily predictions across the greater Mexico City area for 2004–2014. We calibrated the association of AOD to PM2.5 daily using municipal ground monitors, land use, and meteorological features. Predictions used spatial and temporal smoothing to estimate AOD when satellite data were missing. Our model performed well, resulting in an out-of-sample cross validation R2 of 0.724. Cross-validated root mean squared prediction error (RMSPE) of the model was 5.55 μg/m3. This novel model reconstructs long- and short-term spatially resolved exposure to PM2.5 for epidemiological studies in Mexico City. PMID:26061488

  20. Interpenetration and deflection phenomena in collisions between supersonic, magnetized, tungsten plasma flows diagnosed using high resolution optical Thomson scattering

    SciTech Connect

    Swadling, G. F.; Lebedev, S. V.; Burdiak, G.; Suttle, L.; Patankar, S.; Smith, R. A.; Bennett, M.; Hall, G. N.; Suzuki-Vidal, F.; Bland, S.; Harvey-Thompson, A. J.; Rozmus, W.; Yuan, J.

    2015-07-15

    An optical Thomson scattering diagnostic has been used to investigate collisions between supersonic, magnetized plasma flows, in particular the transition from collisionless to collisional interaction dynamics. These flows were produced using tungsten wire array z-pinches, driven by the 1.4 MA 240 ns Magpie generator at Imperial College London. Measurements of the collective-mode Thomson scattering ion-feature clearly indicate that the ablation flows are interpenetrating at 100 ns (after current start), and this interpenetration continues until at least 140 ns. The Thomson spectrum at 150 ns shows a clear change in the dynamics of the stream interactions, transitioning towards a collisional, shock-like interaction of the streams near the axis. The Thomson scattering data also provide indirect evidence of the presence of a significant toroidal magnetic field embedded in the “precursor” plasma near the axis of the array over the period 100–140 ns; these observations are in agreement with previous measurements [Swadling et al., Phys. Rev. Lett. 113, 035003 (2014)]. The Thomson scattering measurements at 150 ns suggest that this magnetic field must collapse at around the time the dense precursor column begins to form.

  1. Using High-Resolution Satellite Aerosol Optical Depth To Estimate Daily PM2.5 Geographical Distribution in Mexico City.

    PubMed

    Just, Allan C; Wright, Robert O; Schwartz, Joel; Coull, Brent A; Baccarelli, Andrea A; Tellez-Rojo, Martha María; Moody, Emily; Wang, Yujie; Lyapustin, Alexei; Kloog, Itai

    2015-07-21

    Recent advances in estimating fine particle (PM2.5) ambient concentrations use daily satellite measurements of aerosol optical depth (AOD) for spatially and temporally resolved exposure estimates. Mexico City is a dense megacity that differs from other previously modeled regions in several ways: it has bright land surfaces, a distinctive climatological cycle, and an elevated semi-enclosed air basin with a unique planetary boundary layer dynamic. We extend our previous satellite methodology to the Mexico City area, a region with higher PM2.5 than most U.S. and European urban areas. Using a novel 1 km resolution AOD product from the MODIS instrument, we constructed daily predictions across the greater Mexico City area for 2004-2014. We calibrated the association of AOD to PM2.5 daily using municipal ground monitors, land use, and meteorological features. Predictions used spatial and temporal smoothing to estimate AOD when satellite data were missing. Our model performed well, resulting in an out-of-sample cross-validation R(2) of 0.724. Cross-validated root-mean-squared prediction error (RMSPE) of the model was 5.55 μg/m(3). This novel model reconstructs long- and short-term spatially resolved exposure to PM2.5 for epidemiological studies in Mexico City. PMID:26061488

  2. High resolution radio and optical observations of the central starburst in the low-metallicity dwarf galaxy II Zw 40

    SciTech Connect

    Kepley, Amanda A.; Reines, Amy E.; Johnson, Kelsey E.; Walker, Lisa May E-mail: areines@nrao.edu E-mail: lisamay@virginia.edu

    2014-02-01

    The extent to which star formation varies in galaxies with low masses, low metallicities, and high star formation rate surface densities is not well constrained. To gain insight into star formation under these physical conditions, this paper estimates the ionizing photon fluxes, masses, and ages for young massive clusters in the central region of II Zw 40—the prototypical low-metallicity dwarf starburst galaxy—from radio continuum and optical observations. Discrete, cluster-sized sources only account for half the total radio continuum emission; the remainder is diffuse. The young (≲ 5 Myr) central burst has a star formation rate surface density that significantly exceeds that of the Milky Way. Three of the 13 sources have ionizing photon fluxes (and thus masses) greater than R136 in 30 Doradus. Although isolating the effects of galaxy mass and metallicity is difficult, the H II region luminosity function and the internal extinction in the center of II Zw 40 appear to be primarily driven by a merger-related starburst. The relatively flat H II region luminosity function may be the result of an increase in interstellar medium pressure during the merger and the internal extinction is similar to that generated by the clumpy and porous dust in other starburst galaxies.

  3. Analysis of the Outer Retina Reconstructed by High-Resolution, Three-Dimensional Spectral Domain Optical Coherence Tomography

    PubMed Central

    Kaluzny, Jakub J.; Wojtkowski, Maciej; Sikorski, Bartosz L.; Szkulmowski, Maciej; Szkulmowska, Anna; Bajraszewski, Tomasz; Fujimoto, James G.; Duker, Jay S.; Schuman, Joel S.; Kowalczyk, Andrzej

    2009-01-01

    Background and Objective A retrospective cross-sectional study was conducted to demonstrate an analysis of an outer retinal layer reconstructed by the three-dimensional and high-speed spectral domain optical coherence tomography (SD-OCT) instrument. Patients and Methods New measurement protocols for SD-OCT and methods of analysis and visualization of the individual segmented retinal layer reconstructed by SD-OCT were proposed. Three contour maps representing mutual distances between the basal part of the retinal pigment epithelium, the junction between the inner and outer segments of photoreceptors, and a reference contour representing the shape of a healthy retina were introduced. Results The analysis of the outer retina was performed on pathological eyes. Three cases of central serous chorioretinopathy, age-related macular degeneration, and acute zonal occult outer retinopathy are demonstrated. Conclusion Three contour maps reconstructed for clinical cases demonstrate high variability of observed patterns depending on analyzed pathology. The authors believe this can help to present OCT data simultaneously in a more comprehensive and convenient way to assist in everyday clinical diagnosis. PMID:19320297

  4. Using High-Resolution Satellite Aerosol Optical Depth To Estimate Daily PM2.5 Geographical Distribution in Mexico City.

    PubMed

    Just, Allan C; Wright, Robert O; Schwartz, Joel; Coull, Brent A; Baccarelli, Andrea A; Tellez-Rojo, Martha María; Moody, Emily; Wang, Yujie; Lyapustin, Alexei; Kloog, Itai

    2015-07-21

    Recent advances in estimating fine particle (PM2.5) ambient concentrations use daily satellite measurements of aerosol optical depth (AOD) for spatially and temporally resolved exposure estimates. Mexico City is a dense megacity that differs from other previously modeled regions in several ways: it has bright land surfaces, a distinctive climatological cycle, and an elevated semi-enclosed air basin with a unique planetary boundary layer dynamic. We extend our previous satellite methodology to the Mexico City area, a region with higher PM2.5 than most U.S. and European urban areas. Using a novel 1 km resolution AOD product from the MODIS instrument, we constructed daily predictions across the greater Mexico City area for 2004-2014. We calibrated the association of AOD to PM2.5 daily using municipal ground monitors, land use, and meteorological features. Predictions used spatial and temporal smoothing to estimate AOD when satellite data were missing. Our model performed well, resulting in an out-of-sample cross-validation R(2) of 0.724. Cross-validated root-mean-squared prediction error (RMSPE) of the model was 5.55 μg/m(3). This novel model reconstructs long- and short-term spatially resolved exposure to PM2.5 for epidemiological studies in Mexico City.

  5. First High-Resolution Record of Late Quaternary Environmental Changes in the Amundsen Sea, West Antarctica, Revealed by Multi-proxy Analysis of Drift Sediments

    NASA Astrophysics Data System (ADS)

    Horrocks, J.; Ó Cofaigh, C.; Lloyd, J. M.; Hillenbrand, C. D.; Kuhn, G.; Smith, J.; Ehrmann, W. U.; Esper, O.

    2015-12-01

    The Amundsen Sea sector of the West Antarctic Ice Sheet (WAIS) is experiencing rapid mass loss and there is a pressing need to place the contemporary ice-sheet changes into a longer term context. The continental rise in this region is characterised by large sediment mounds that are shaped by westward flowing bottom currents and that resemble contouritic drifts existing offshore from the Antarctic Peninsula. Similar to the Antarctic Peninsula drifts, marine sediment cores from the poorly studied sediment mounds in the Amundsen Sea have the potential to provide reliable records of dynamical ice-sheet behaviour in West Antarctica and palaeoceanographic changes in the Southern Ocean during the Late Quaternary that can be reconstructed from their terrestrial, biogenic and authigenic components. Here we use multi-proxy data from three sediment cores recovered from two of the Amundsen Sea mounds to present the first high-resolution study of environmental changes on this part of the West Antarctic continental margin over the glacial-interglacial cycles of the Late Quaternary. Age constraints for the records are derived from biostratigraphy, AMS 14C dates and lithostratigraphy. We focus on the investigation of processes for drift formation, thereby using grain size and sortable silt data to reconstruct changes in bottom current speed and to identify episodes of current winnowing. Data on geochemical and mineralogical sediment composition and physical properties are used to infer both changes in terrigenous sediment supply in response to the advance and retreat of the WAIS across the Amundsen Sea shelf and changes in biological productivity that are mainly controlled by the duration of annual sea-ice coverage. We compare our data sets from the Amundsen Sea mounds to those from the well-studied Antarctic Peninsula drifts, thereby highlighting similarities and discrepancies in depositional processes and climatically-driven environmental changes.

  6. High resolution δ 18O and δ 13C records from an annually laminated Scottish stalagmite and relationship with last millennium climate

    NASA Astrophysics Data System (ADS)

    Baker, Andy; Wilson, Rob; Fairchild, Ian J.; Franke, Joerg; Spötl, Christoph; Mattey, Dave; Trouet, Valerie; Fuller, Lisa

    2011-12-01

    High-resolution (annual to decadal) stable isotope records of oxygen and carbon are analysed from an annually laminated stalagmite from NW Scotland. The sample, which was deposited for ~ 1000 yrs until 1996 AD, has previously provided annual resolution climate reconstructions of local rainfall and regional winter North Atlantic Oscillation (wNAO) from variations in annual growth rate. For our stalagmite, for which modern cave monitoring demonstrates that equilibrium deposition is highly likely for δ 18O but not for δ 13C, stalagmite δ 13C originally derives from soil CO 2 produced predominantly by microbial respiration, modified by degassing-related kinetic fractionation, and δ 18O from the composition of infiltrating water during periods of infiltrating water. Both the presence of fluorescent laminae and modern drip-water monitoring demonstrate a drip hydrology that comprises both event and storage components. Over the instrumental period, no correlations between stalagmite or rainfall δ 18O and precipitation amount or temperature are observed, but correlations are observed between rainfall δ 18O and 500 mb height at regional IAEA monitoring stations. However, no correlations are observed between stalagmite δ 18O and instrumental and reconstructed atmospheric circulation, preventing a simple palaeoclimate interpretation of the stalagmite δ 18O proxy. Stalagmite δ 13C has a stronger temporal autocorrelation than δ 18O, indicative of soil mixing of respired CO 2 and significant variability between drips and at different times; correlations with instrumental climate data are therefore not possible. The relative timing of changes in growth rate, δ 18O and δ 13C are discussed, and interpretations compared with other regional climate records. We conclude that, over the last millennium at this mid-latitude cave site, neither δ 18O nor δ 13C cannot be interpreted as a simple paleoclimate proxy.

  7. High resolution Holocene temperature records for the northeastern United States from hydrogen isotope ratios of mid-chain aquatic plant lipids

    NASA Astrophysics Data System (ADS)

    Gao, L.; Huang, Y.; Hou, J.; Shuman, B. N.; Oswald, W.; Foster, D. R.

    2011-12-01

    Holocene temperature changes for the northeastern U.S. are poorly defined due to the lack of suitable proxies. We developed a mathematic model to quantify the percentage contribution of aquatic plants to the mid-chain n-alkyl lipids in lake sediments (Gao et al., GCA, 2011). We show that Little Pond in Royalston, Massachusetts is characterized by exceptionally high percentages (>90%) of aquatic contribution to the mid-chain n-alkyl lipids in sediments, and generated a quantitative, high-resolution Holocene temperature record based on compound-specific D/H ratio of behenic acid (δDBA) (Figure). Our record shows that the Laurentide Ice Sheet suppressed the regional temperature by ~ 2 °C during the early Holocene. Numerous rapid and large (~4.9 °C) climate oscillations occurred as a result of major freshwater outbursts and the resulting changes in North Atlantic meridional overturning circulation. Following a major climate reversal at 8.2 ka, the regional climatic optimum occurred between ~8 ka and ~7 ka BP. Temperature gradually declined from ~8ka toward present by ~3.9 °C associated with the declining summer insolation. During the past two millennia, temperature changes closely mimic the synthesized borehole temperatures, with a temperature trough at ~1.8 ka and a peak at ~0.5 ka. Regional temperature does not show the typical little ice age trends, except a minimal temperature (~7 °C) at ~1850 A.D, which is followed by rapid temperature rise probably as a result of anthropogenic forcing. Combined with our previous data from Blood Pond, we have obtained centennial scale temperature history for the New England region for the past 15000 years.

  8. High-Resolution fMRI Maps of Cortical Activation in Nonhuman Primates: Correlation with Intrinsic Signal Optical Images

    PubMed Central

    Roe, Anna W.; Chen, Li Min

    2009-01-01

    One of the most widely used functional brain mapping tools is blood oxygen level–dependent (BOLD) functional magnetic resonance imaging (fMRI). This method has contributed to new understandings of the functional roles of different areas in the human brain. However, its ability to map cerebral cortex at high spatial (submillimeter) resolution is still unknown. Other methods such as single- and multiunit electrophysiology and intrinsic signal optical imaging have revealed submillimeter resolution of sensory topography and cortical columnar activations. However, they are limited either by spatial scale (electrophysiology characterizes only local groups of neurons) or by the inability to monitor deep structures in the brain (i.e., cortical regions buried in sulci or subcortical structures). A method that could monitor all regions of the brain at high spatial resolution would be ideal. This capacity would open the doors to investigating, for example, how networks of cerebral cortical columns relate to or produce behavior. In this article we demonstrate that, without benefit of contrast agents, at a magnetic field strength of 9.4 tesla, BOLD fMRI can reveal millimeter-sized topographic maps of digit representation in the somatosensory cortex of the anesthetized squirrel monkey. Furthermore, by mapping the “funneling illusion,” it is possible to detect even submillimeter shifts in activation in the cortex. Our data suggest that at high magnetic field strength, the positive BOLD signal can be used to reveal high spatial resolution maps of brain activity, a finding that weakens previous notions about the ultimate spatial specificity of the positive BOLD signal. PMID:18172338

  9. Spaceflight optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Jurczyk, Stephen G.; Hines, Glenn D.; Shull, Thomas A.

    1992-01-01

    Mass memory systems based on rewriteable optical disk media are expected to play an important role in meeting the data system requirements for future NASA spaceflight missions. NASA has established a program to develop a high performance (high rate, large capacity) optical disk recorder focused on use aboard unmanned Earth orbiting platforms. An expandable, adaptable system concept is proposed based on disk drive modules and a modular controller. Drive performance goals are 10 gigabyte capacity, 300 megabit/s transfer rate, 10 exp -12 corrected bit error rate, and 150 millisec access time. This performance is achieved by writing eight data tracks in parallel on both sides of a 14 in. optical disk using two independent heads. System goals are 160 gigabyte capacity, 1.2 gigabits/s data rate with concurrent I/O, 250 millisec access time, and two to five year operating life on orbit. The system can be configured to meet various applications. This versatility is provided by the controller. The controller provides command processing, multiple drive synchronization, data buffering, basic file management, error processing, and status reporting. Technology developments, design concepts, current status including a computer model of the system and a Controller breadboard, and future plans for the Drive and Controller are presented.

  10. Solar influence on climate variability and human development during the Neolithic: evidence from a high-resolution multi-proxy record from Templevanny Lough, County Sligo, Ireland

    NASA Astrophysics Data System (ADS)

    Stolze, Susann; Muscheler, Raimund; Dörfler, Walter; Nelle, Oliver

    2013-05-01

    The relationship between climatic variations, vegetation dynamics and early human activity between c. 4150-2860 BC was reconstructed from a high-resolution pollen and geochemical record obtained from a small lake located in County Sligo, Ireland. The proxy record suggests the existence of a woodland with a largely closed canopy at the start of the fourth millennium BC. Only minor human disturbance is recorded. Following an episode of increased rainfall at c. 3990 BC, a decrease in the elm population occurred between c. 3970 and 3820 BC. This coincided with a period of warming and drying climatic conditions and an initial increase in anthropogenic activities. A second episode of high precipitation between c. 3830-3800 BC was followed by a steep increase in human impact on the landscape, which became most pronounced between c. 3740 and 3630 BC. At this time, the lake level of Templevanny Lough was at its lowest during the Neolithic. The onset of wetter and cooler conditions after c. 3670 BC, representing the transition from the Early to the Middle Neolithic, coincided with a period of woodland recovery. The Middle Neolithic was characterised by pronounced climatic oscillations including periods of substantial rainfall between c. 3600 and 3500 BC and between c. 3500 and 3460 BC. A nearly century-long climatic amelioration between c. 3460-3370 BC facilitated a revival of human activity on a small scale around the lake. Abandonment of the area and full woodland recovery occurred after a period of particularly wet and cool conditions ranging from c. 3360-3290 BC. The pollen and geochemistry data suggest that the Late Neolithic was marked by a period of ameliorated conditions between c. 3110-3050 BC that was followed by two episodes of high rainfall at c. 3060-3030 BC and c. 2940-2900 BC. The timing of the climatic shifts inferred from the Templevanny Lough record is in agreement with those of moisture/precipitation and temperature reconstructions from northern and

  11. A complete high resolution record of the Dan-C2 hyperthermal event in the lacustrine sediments of the Boltysh Impact crater

    NASA Astrophysics Data System (ADS)

    Gilmour, I.; Jolley, D. W.; Daly, R. J.; Kelley, S. P.; Gilmour, M. A.

    2012-04-01

    Drilling of the 65.17 Ma old, 24 km diameter, Boltysh impact crater in the Ukraine recovered over 400 m of Danian organic-rich lacustrine sediments [1]. We have undertaken geochemical and palynological investigations of the newly cored borehole, which demonstrate that these strata contain a unique high resolution record spanning <0.5 Ma of Early Palaeocene terrestrial environmental change. The palynofloras recovered are consistent with terrestrial early Danian successions and geochemical data have highlighted a record that extends through 220m of cored sediments encompassing the earliest Danian Dan-C2 hyperthermal event first identified by [2]. To date, the Dan-C2 hyperthermal event has been identified in marine records, where it is characterised by a pair of negative carbon isotope excursions (CIEs) of around 1.5‰ within planktonic foraminiferal zone P1a, post-dating the K/Pg boundary. Geochemical and palynological investigations have enabled us to identify the Dan-C2 event in the lacustrine Boltysh crater fill where it is characterised by a 3-4‰ negative CIE. In common with other hyperthermal events, it has been suggested that the Dan-C2 reflects transient perturbations in the global carbon cycle, however, whether the Dan-C2 is a global event has been disputed. The event has been confirmed in the S. Atlantic but was not found in the equatorial Pacific leading to the suggestion that it was restricted to the Atlantic Ocean [3]. Its presence in the lacustrine sediments of the Boltysh crater fill disproves this contention. The Dan-C2 CIE has also been regarded as being of shorter duration and lower magnitude than the PETM hyperthermal [2]. This view is brought into question by the Boltysh carbon isotope record, which highlights the close comparability of Toarcian, Dan-C2 and PETM excursions. We have also have established the position of the Dan-C2 with respect to the K/Pg boundary [1] since its close proximity this boundary, also marked by a negative CIE, makes

  12. High-Resolution Imaging of Parafoveal Cones in Different Stages of Diabetic Retinopathy Using Adaptive Optics Fundus Camera

    PubMed Central

    Soliman, Mohamed Kamel; Hassan, Muhammad; Hanout, Mostafa; Graf, Frank; High, Robin; Do, Diana V.; Nguyen, Quan Dong; Sepah, Yasir J.

    2016-01-01

    Purpose To assess cone density as a marker of early signs of retinopathy in patients with type II diabetes mellitus. Methods An adaptive optics (AO) retinal camera (rtx1™; Imagine Eyes, Orsay, France) was used to acquire images of parafoveal cones from patients with type II diabetes mellitus with or without retinopathy and from healthy controls with no known systemic or ocular disease. Cone mosaic was captured at 0° and 2°eccentricities along the horizontal and vertical meridians. The density of the parafoveal cones was calculated within 100×100-μm squares located at 500-μm from the foveal center along the orthogonal meridians. Manual corrections of the automated counting were then performed by 2 masked graders. Cone density measurements were evaluated with ANOVA that consisted of one between-subjects factor, stage of retinopathy and the within-subject factors. The ANOVA model included a complex covariance structure to account for correlations between the levels of the within-subject factors. Results Ten healthy participants (20 eyes) and 25 patients (29 eyes) with type II diabetes mellitus were recruited in the study. The mean (± standard deviation [SD]) age of the healthy participants (Control group), patients with diabetes without retinopathy (No DR group), and patients with diabetic retinopathy (DR group) was 55 ± 8, 53 ± 8, and 52 ± 9 years, respectively. The cone density was significantly lower in the moderate nonproliferative diabetic retinopathy (NPDR) and severe NPDR/proliferative DR groups compared to the Control, No DR, and mild NPDR groups (P < 0.05). No correlation was found between cone density and the level of hemoglobin A1c (HbA1c) or the duration of diabetes. Conclusions The extent of photoreceptor loss on AO imaging may correlate positively with severity of DR in patients with type II diabetes mellitus. Photoreceptor loss may be more pronounced among patients with advanced stages of DR due to higher risk of macular edema and its

  13. High-resolution multi-molecular stratigraphic records from North Atlantic drift sediments (ODP Sites 980, 984) reflecting Holocene climate and ocean dynamics

    NASA Astrophysics Data System (ADS)

    Holtvoeth, J.; Wagner, T.; Montlucon, D.; Mollenhauer, G.; McManus, J. F.; Oppo, D. W.; Eglinton, T. I.

    2005-12-01

    The North Atlantic plays an important role as the source region for northern component waters of thermohaline circulation. The hydrological system is highly sensitive to climatic changes. Underlying drift sediments record both changes in the hydrological system (lateral advection) and in `direct' material input from surface waters (primary production and eolian supply), and therefore represent excellent archives for past ocean and regional climate variability. Two sediment cores from North Atlantic drift sediments were taken during ODP Leg 162 (Site 980, Feni Drift, 55°N 15°W, water depth 2179 m, and Site 984, Bjorn Drift, 61°N 24°W, water depth 1648 m). While both sites experience similar atmospheric forcing, the present-day Bjorn Drift is bathed by Iceland-Scotland Overflow Water, while the Feni Drift is influenced by more southern sourced waters. Both sites exhibit exceptionally high sedimentation rates and thus enable reconstruction of climate-related changes within the North Atlantic with high temporal resolution. The composition of the organic matter (OM) in these sediments is closely coupled to the dynamics of the environment. Key factors that control quantity and quality of OM from marine and terrigenous sources in the drift sediments are surface water temperature and nutrient supply (marine primary productivity), wind speed (eolian supply of terrigenous OM), and strength and direction of bottom water currents (lateral redistribution of OM and export from continental margins). This study seeks evidence for rapid climate changes through development of high-resolution multi-molecular stratigraphic records of the sedimentary OM using Gas Chromatography/Time-Of-Flight Mass Spectrometry (GC-TOF-MS) analysis of total lipid extracts. We present high-resolution (< 100 yr) molecular proxy records from both ODP sites that indicate changes in heat transport, marine productivity, and terrigenous supply from the Last Glacial Maximum to the present. Alkenones

  14. Middle and Late Holocene climate in the tropics : contribution of a high-resolution palynological and geochemical record in northwestern Colombia

    NASA Astrophysics Data System (ADS)

    Muñoz Uribe, P.; Jojoa, M.; Velásquez, C.; Gorin, G. E.

    2009-12-01

    Records of climate change in the tropics are particularly important because it is where major thermal energy interchanges take place between oceans and atmosphere. Climate events like the ENSO and ITCZ are associated with the tropics, but influence the global climate. High-resolution data are needed to look for their potential signature in the Holocene. Among all the paleoclimate proxies in the continental realm, palynology has been used extensively in the Holocene to study climatically-induced environmental changes. The high-altitude wet zones (ca. 3’500 m amsl) of the Páramo de Frontino in the northwestern termination of the Colombian Andes are strategically exposed to influences from both the Pacific and Atlantic oceans. In the studied wet zone, a ca. 7 m thick, continuous, sedimentary record spanning the last 9’000 years has been cored and studied by palynology and X-ray fluorescence. Palynological data with a time-resolution of less than 50 years provide information on the vertical migration of vegetation belts, indicative of climate variations. The geochemical signature of cored sediments derived from X-ray fluorescence is another potential proxy for climatically-induced environmental parameters, essentially related to pluviosity, erosion rates in the drainage basin and variations of the water table in the wet zone. Palynological data from the Páramo de Frontino document vegetation changes and related variations in temperature and humidity in the northern part of the Western Cordillera over the last 9’000 years. The upper part of the Early Holocene is warm and dry. A major change occurs at the transition between Early and Middle Holocene with the onset of a very humid and less warm climate during the Middle Holocene. The Middle Holocene climatic optimum is not observed in the Western Cordillera, which records much higher humidity than in the Central and Eastern cordilleras. Many fluctuations in temperature and humidity occurred during the Late

  15. A High-Resolution Absolute-Dated Penultimate Glacial Monsoon Record From Hulu and Dongge Caves, China and Global Correlations of Events Surrounding Termination II

    NASA Astrophysics Data System (ADS)

    Cheng, H.; Kelly, M. J.; Edwards, R. L.; Wang, Y.; Kong, X.; Ming, Y.; Liu, W.; Cai, Y.; An, Z.; Yuan, D.; Zhang, M.; Lin, Y.

    2004-12-01

    We have obtained the oxygen isotope record of three stalagmites from Hulu Cave (eastern China, 32° 30'N, 119° 10'E), offering a high-resolution absolute-dated record of Asian monsoon climate over much of the penultimate glacial period. Previously, stalagmites were analyzed from Dongge Cave (southern China, 25° 17'N, 108° 5'E), located approximately 1200 km to the southwest of Hulu Cave, providing a detailed account of δ 18O variations over about the same time period (Yuan et al., 2004; Kelly et al., in review). The δ 18O patterns from the Hulu and Dongge stalagmites appear to be broadly similar across the overlapping portions of the records, indicating that the stalagmites are recording a regional climate signal. Asian Monsoon climate during the penultimate glacial period follows orbitally induced insolation changes, though it is punctuated by numerous sub-orbital scale climate events. The heaviest δ 18O values during the penultimate glacial period were initiated at ˜136 ka B.P. in both records, and are largely maintained for the next ˜6 kyr until abrupt strengthening of the monsoon at Monsoon Termination II. This interval is generally characterized by less variability than seen during the earlier portions of MIS 6, with δ 18O values remaining around -5‰ . Kelly et al. (in review) have called this extended interval of time the "Weak Monsoon Interval" (WMI). The WMI, however, is punctuated by one distinct climate event, occurring at 134.5 ± 1.0 ka B.P. in the Hulu record and 133.6 ± 1.0 ka B.P. in the Dongge record. This event may correlate with warming in the Alps at 135 ± 1.2 ka B.P., as indicated by an interval of speleothem growth from Spannagel Cave (Spötl et al., 2002). We also demonstrate that the monsoon intensity correlates well with atmospheric CH4 concentrations over the last two glacial cycles. In particular, we correlate the abrupt jump in CH4 concentrations at ˜129 ka B.P. with our Monsoon Termination II. Based upon this correlation

  16. Late-Holocene climate change derived from a high-resolution pollen record from varved sediments at Sugan Lake in the Qaidam Basin, northeastern Tibetan Plateau

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Zhang, K.; Yu, Z.; Zhou, A.

    2010-12-01

    A 2700-yr high-resolution pollen record from annually-varved sediments at Sugan Lake in the Qaidam Basin (2793 m a.s.l) was obtained to examine vegetation and climatic change on the NE Tibetan Plateau. Fossil pollen data show that the area was constantly covered by open desert-steppe vegetation dominated by Chenopodiaceae, Artemisia, Poaceae and Ephedra. Artemisia/Chenopodiaceae (A/C) ratios, representing relative abundance of steppe vs. desert plants on the surrounding landscape, suggest large regional moisture fluctuations over the last 2700 years, including (1) a dry and relatively stable climate prior to 300 AD, (2) a relatively wet climate at 300-1200 AD with higher variability at 1100-1200 AD, and (3) a highly unstable climate since 1200 AD, with relatively moist intervals at 1250-1400 AD and at 1700-1800 AD. However, other proxies from the same site (including varve thickness, Chironomid assemblages, and oxygen isotopes of precipitated carbonate) show different or even opposite moisture patterns as inferred from pollen data. This inconsistency and divergence suggest possible different responses of in-lake and watershed processes to the same climate change. For example, increase in freshwater input to the lake from ice melting origined from the surrounding mountains might have contributed to high lake level and moist conditions as interpreted from other proxies, even if there are no increases in precipitation in the low-elevation basin during the same periods. Furthermore, the effective moisture changes in the Basin are opposite in trend with snow accumulation records from Dunde ice core (5325 m a.s.l) and with the monsoon intensity inferred from Dongge Cave, suggesting that the regional topography on the Tibetan Plateau might have played an important role in mediating regional moisture changes. The shift in effective moisture at 1200 AD from stable to more variable conditions as inferred from our pollen data at Sugan Lake is also observed in other

  17. A high resolution Late Glacial to Holocene record of climatic and environmental change in the Mediterranean from Lake Ohrid (Macedonia/Albania)

    NASA Astrophysics Data System (ADS)

    Lacey, Jack; Francke, Alexander; Leng, Melanie; Vane, Chris; Wagner, Bernd

    2015-04-01

    Lake Ohrid (Macedonia/Albania) is one of the world's oldest lakes and is renowned for its high degree of biological diversity. It is the target site for the ICDP SCOPSCO (Scientific Collaboration on Past Speciation Conditions in Lake Ohrid) project, an international research initiative to study the links between geology, environment and the evolution of endemic taxa. In 2011 a 10-meter core was recovered from the western shore of Lake Ohrid adjacent to the Lini Peninsula. Here we present high-resolution stable isotope and geochemical data from this core through the Late Glacial to Holocene to reconstruct past climate and hydrology (TIC, δ18Ocalcite, δ13Ccalcite) as well as the terrestrial and aquatic vegetation response to climate (TOC, TOC/N, δ13Corganic, Rock-Eval pyrolysis). The data identify 3 main zones: (1) the Late Glacial-Holocene transition represented by low TIC, TOC and higher isotope values, (2) the early to mid-Holocene characterised by higher TOC, TOC/N and lower δ18Ocalcite, and (3) the late Holocene which shows a marked decrease in TIC and TOC. In general there is an overall trend of increasing δ18Ocalcite from 9 ka to present, suggesting progressive aridification through the Holocene, which is consistent with previous records from Lake Ohrid and the wider Mediterranean region. Several proxies show commensurate excursions that imply the impact of short-term climate oscillations, such as the 8.2 ka event and the Little Ice Age. This is the best-dated and highest resolution archive of Late Glacial and Holocene climate from Lake Ohrid and confirms the overriding influence of the North Atlantic in the north-eastern Mediterranean. The data presented set the context for the SCOPSCO project cores recovered in spring-summer 2013 dating back into the Lower Pleistocene, and will act as a recent calibration to reconstruct climate and hydrology over the entire lake history.

  18. A high-resolution Late Glacial to Holocene record of environmental change in the Mediterranean from Lake Ohrid (Macedonia/Albania)

    NASA Astrophysics Data System (ADS)

    Lacey, Jack H.; Francke, Alexander; Leng, Melanie J.; Vane, Christopher H.; Wagner, Bernd

    2015-09-01

    Lake Ohrid (Macedonia/Albania) is the oldest extant lake in Europe and exhibits an outstanding degree of endemic biodiversity. Here, we provide new high-resolution stable isotope and geochemical data from a 10 m core (Co1262) through the Late Glacial to Holocene and discuss past climate and lake hydrology (TIC, δ13Ccalcite, δ18Ocalcite) as well as the terrestrial and aquatic vegetation response to climate (TOC, TOC/N, δ13Corganic, Rock Eval pyrolysis). The data identifies 3 main zones: (1) the Late Glacial-Holocene transition represented by low TIC and TOC contents, (2) the early to mid-Holocene characterised by high TOC and increasing TOC/N and (3) the Late Holocene-Present which shows a marked decrease in TIC and TOC. In general, an overall trend of increasing δ18Ocalcite from 9 ka to present suggests progressive aridification through the Holocene, consistent with previous records from Lake Ohrid and the wider Mediterranean region. Several proxies show commensurate excursions that imply the impact of short-term climate oscillations, such as the 8.2 ka event and the Little Ice Age. This is the best-dated and highest resolution archive of past Late Glacial and Holocene climate from Lake Ohrid and confirms the overriding influence of the North Atlantic in the north-eastern Mediterranean. The data presented set the context for the International Continental scientific Drilling Program Scientific Collaboration On Past Speciation Conditions in Lake Ohrid project cores recovered in spring-summer 2013, potentially dating back into the Lower Pleistocene, and will act as a recent calibration to reconstruct climate and hydrology over the entire lake history.

  19. Entire thickness profiles of the epithelium and contact lens in vivo imaged with high speed and high resolution optical coherence tomography

    PubMed Central

    Tao, Aizhu; Shao, Yilei; Jiang, Hong; Ye, Yufeng; Lu, Fan; Shen, Meixiao; Zhu, Dexi; Wang, Jianhua

    2013-01-01

    Purpose To test the feasibility of measuring the entire thickness profiles of the epithelium and contact lens in vivo, using high speed and high resolution spectral domain optical coherence tomography (SD-OCT). Methods A custom-built, long scan depth SD-OCT was developed based on a CMOS camera and the axial resolution was about 5.1 µm in tissue. Five eyes of 5 subjects were imaged twice across the horizontal meridian before and while wearing one contact lens (CL). Semi-automatic measurement was done to yield the entire thickness profiles of the epithelium, total cornea, and contact lens after correcting for optical distortion. Results The full width and depth of the epithelium, ocular surface and contact lens were clearly visualized. The epithelial thickness (ET) at the center was 51.9 ± 3.5 µm, it remained at this thickness across the central 7 mm diameter and then increased at both temporal and nasal peripheries. The contact lens profile showed the thinnest point at the center with thickness of 100.3 ± 4.9 µm. The thickness increased towards the mid-periphery and then decreased at the edge. Conclusions This pilot study demonstrated the feasibility of using high speed CMOS-based OCT to evaluate the entire thickness profiles of the epithelium and contact lens in vivo. Further development will be needed to extend the scanning from 2D to 3D with a robust automatic image processing ability. PMID:23982471

  20. Environmental change at the southern Cape coast of South Africa as inferred from a high-resolution Holocene sediment record from Eilandvlei

    NASA Astrophysics Data System (ADS)

    Wündsch, Michael; Haberzettl, Torsten; Meadows, Michael E.; Kirsten, Kelly L.; Meschner, Stephanie; Frenzel, Peter; Baade, Jussi; Daut, Gerhard; Mäusbacher, Roland; Kasper, Thomas; Quick, Lynne J.; Cawthra, Hayley C.; Zabel, Matthias

    2016-04-01

    reservoir effects for the older deposits. This indicates a temporal variability on the degree of old marine carbon affecting Eilandvlei during the Holocene, which was possibly caused by changes in the connectivity between the lake system and the ocean as well as changes in the extent of upwelling along the coast. To solve this problem, variable past reservoir effects were determined based on the dating of sample pairs which were assumingly deposited contemporaneously and are composed of different source material (marine/terrestrial). This approach provides the most reliable chronology revealing a median basal age of 8880 +145/220 cal BP. Thus, the Eilandvlei core represents an ultra-high-resolution record of environmental change during the Holocene, which is a unique discovery for entire southern Africa. Palaeoenvironmental interpretations of the this record strongly suggest that sedimentation conditions at Eilandvlei were closely coupled to global sea level changes. Moreover, the multi-proxy approach provides great potential for palaeoclimatic interpretations of this record. For example, geochemical proxies reflecting the varying input of terrestrial material suggest changes in the discharge of inflowing rivers which, in turn, may be linked to variations in rainfall and hence climate within the year-round rainfall zone of South Africa.

  1. Cross-continent comparison of high-resolution Holocene climate records from southern Australia — Deciphering the impacts of far-field teleconnections

    NASA Astrophysics Data System (ADS)

    Gouramanis, Chris; De Deckker, Patrick; Switzer, Adam D.; Wilkins, Daniel

    2013-06-01

    Several well-dated and high-resolution, multi-proxy Holocene palaeoclimatic records have recently emerged that permit a cross-continent comparison of climatic changes in Australia. This synthesis seeks to compare these records with recently published records from southern Australia and investigate the role of far-field teleconnections that have played in the mid to late Holocene climatic history of the region. The modern climate of southeastern Australia (SEA) is influenced by the Indian Ocean sector of the Southern Annular Mode (IOS-SAM), the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) and contrasts with southwestern Australia (SWA), which is predominantly influenced by variations in the IOS-SAM. Both regions have undergone a period of increasing aridity through the second half of the Holocene in response to the southerly migration of the mean position of the Inter-Tropical Convergence Zone (ITCZ) and the southerly migration of the IOS-SAM. Comparison of the palaeorecords stemming from both SEA and SWA suggests that the SWA record differs from the climate recorded from SEA from approximately 5.6 ka. This difference is ascribed to an increased influence of large-scale climate drivers including the IOD and ENSO variability in SEA, which have negligible impact on the climate of SWA. Throughout the Holocene, the southerly migration of the ITCZ results in a weaker Asian summer monsoon. However, the rate of Asian summer monsoon weakening slowed during the middle Holocene and this coincides with a larger sea-surface temperature gradient across the equatorial Indian Ocean that resulted in a prolonged mode of positive IOD and a period of significantly increased evaporation in SEA. Those phenomena engendered a general decline in the lake levels in SEA, which is not seen in SWA as this region was not significantly affected